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Sample records for volume conditioned stimuli

  1. Olfactory classical conditioning in neonatal mouse pups using thermal stimuli.

    Science.gov (United States)

    Bollen, Bieke; Matrot, Boris; Ramanantsoa, Nelina; Van den Bergh, Omer; D'Hooge, Rudi; Gallego, Jorge

    2012-04-01

    Mouse models are increasingly used to investigate genetic contributions to developmental disorders in children, especially newborns. In particular, early cognitive assessment in newborn mice is critical to evaluate pediatric drug efficacy and toxicity. Unfortunately, methods for behavioral tests in newborn mice are scarce. Therefore, developing such tests for newborn mice is a priority challenge for neurogenetics and pharmacological research. The aim of the present study was to develop a conditioning method well suited to high-throughput cognitive screening in newborn mice. To this end, we developed an odor-preference conditioning test using ambient temperature as an unconditioned stimulus (US) and artificial odors as conditioned stimuli (CS). First, we showed that mouse pups move toward the thermoneutral temperature when offered a choice between a thermoneutral and cold environment, thus showing thermotaxis. Second, we conducted a classical conditioning paradigm in pups aged six to ten days. In terms of central nervous system development, this period corresponds to extreme prematurity to early post-term period in humans. During acquisition, the pups were alternatively exposed to odor CS paired with either cold or warm temperatures. Immediately after acquisition, the pups underwent a two-odor choice test, which showed preference for the odor previously paired with the warm temperature, thus showing conditioning. The proposed paradigm is easy to conduct, and requires modest experimenter interference. The method is well suited for high-throughput screening of early associative disorders in newborn mice.

  2. Perseverative instrumental and Pavlovian responding to conditioned stimuli in serotonin transporter knockout rats

    NARCIS (Netherlands)

    Nonkes, L.J.P.; Homberg, J.R.

    2013-01-01

    Environmental stimuli can influence behavior via the process of Pavlovian conditioning. Recent genetic research suggests that some individuals are more sensitive to environmental stimuli for behavioral guidance than others. One important mediator of this effect is serotonin transporter (5-HTT) genet

  3. Evaluative conditioning of high-novelty stimuli does not seem to be based on an automatic form of associative learning

    NARCIS (Netherlands)

    Dedonder, Jonathan; Corneille, Olivier; Yzerbyt, Vincent; Kuppens, Toon

    2010-01-01

    Evaluative conditioning (EC) refers to the change in valence of initially neutral stimuli (conditioned stimuli, or CSs) as a result of their pairing with positive or negative stimuli (unconditioned stimuli, or USs). EC is critical to dual-attitudes models as it is often presented as an evaluative

  4. Evaluative conditioning of high-novelty stimuli does not seem to be based on an automatic form of associative learning

    NARCIS (Netherlands)

    Dedonder, Jonathan; Corneille, Olivier; Yzerbyt, Vincent; Kuppens, Toon

    2010-01-01

    Evaluative conditioning (EC) refers to the change in valence of initially neutral stimuli (conditioned stimuli, or CSs) as a result of their pairing with positive or negative stimuli (unconditioned stimuli, or USs). EC is critical to dual-attitudes models as it is often presented as an evaluative ef

  5. Do long delay conditioned stimuli develop inhibitory properties?

    Directory of Open Access Journals (Sweden)

    Martha eEscobar

    2015-10-01

    Full Text Available In long-delay conditioning, a long conditioned stimulus (CS is paired in its final segments with an unconditioned stimulus. With sufficient training, this procedure usually results in conditioned responding being delayed until the final segment of the CS, a pattern of responding known as inhibition of delay. However, there have been no systematic investigations of the associative structure of long delay conditioning, and whether the initial segment of a long delay CS actually becomes inhibitory is debatable. In an appetitive preparation with rat subjects, the initial segment of long delay CS A passed a retardation (Experiment 1a but not a summation (Experiment 1b test for conditioned inhibition. Furthermore, retardation was observed only if long delay conditioning and retardation training occurred in the same context (Experiment 2. Thus, the initial segment of a long delay CS appears to share more characteristics with a latent inhibitor than a conditioned inhibitor. Componential theories of conditioning appear best suited to account for these results.

  6. Evaluative Conditioning with Facial Stimuli in Dementia Patients.

    Science.gov (United States)

    Blessing, Andreas; Zöllig, Jacqueline; Weierstall, Roland; Dammann, Gerhard; Martin, Mike

    2013-01-01

    We present results of a study investigating evaluative learning in dementia patients with a classic evaluative conditioning paradigm. Picture pairs of three unfamiliar faces with liked, disliked, or neutral faces, that were rated prior to the presentation, were presented 10 times each to a group of dementia patients (N = 15) and healthy controls (N = 14) in random order. Valence ratings of all faces were assessed before and after presentation. In contrast to controls, dementia patients changed their valence ratings of unfamiliar faces according to their pairing with either a liked or disliked face, although they were not able to explicitly assign the picture pairs after the presentation. Our finding suggests preserved evaluative conditioning in dementia patients. However, the result has to be considered preliminary, as it is unclear which factors prevented the predicted rating changes in the expected direction in the control group.

  7. Evaluative Conditioning with Facial Stimuli in Dementia Patients

    Directory of Open Access Journals (Sweden)

    Andreas Blessing

    2013-01-01

    Full Text Available We present results of a study investigating evaluative learning in dementia patients with a classic evaluative conditioning paradigm. Picture pairs of three unfamiliar faces with liked, disliked, or neutral faces, that were rated prior to the presentation, were presented 10 times each to a group of dementia patients (N = 15 and healthy controls (N = 14 in random order. Valence ratings of all faces were assessed before and after presentation. In contrast to controls, dementia patients changed their valence ratings of unfamiliar faces according to their pairing with either a liked or disliked face, although they were not able to explicitly assign the picture pairs after the presentation. Our finding suggests preserved evaluative conditioning in dementia patients. However, the result has to be considered preliminary, as it is unclear which factors prevented the predicted rating changes in the expected direction in the control group.

  8. Fear conditioning to subliminal fear relevant and non fear relevant stimuli.

    Directory of Open Access Journals (Sweden)

    Ottmar V Lipp

    Full Text Available A growing body of evidence suggests that conscious visual awareness is not a prerequisite for human fear learning. For instance, humans can learn to be fearful of subliminal fear relevant images--images depicting stimuli thought to have been fear relevant in our evolutionary context, such as snakes, spiders, and angry human faces. Such stimuli could have a privileged status in relation to manipulations used to suppress usually salient images from awareness, possibly due to the existence of a designated sub-cortical 'fear module'. Here we assess this proposition, and find it wanting. We use binocular masking to suppress awareness of images of snakes and wallabies (particularly cute, non-threatening marsupials. We find that subliminal presentations of both classes of image can induce differential fear conditioning. These data show that learning, as indexed by fear conditioning, is neither contingent on conscious visual awareness nor on subliminal conditional stimuli being fear relevant.

  9. Arbitrary conditional discriminative functions of meaningful stimuli and enhanced equivalence class formation.

    Science.gov (United States)

    Nedelcu, Roxana I; Fields, Lanny; Arntzen, Erik

    2015-03-01

    Equivalence class formation by college students was influenced through the prior acquisition of conditional discriminative functions by one of the abstract stimuli (C) in the to-be-formed classes. Participants in the GR-0, GR-1, and GR-5 groups attempted to form classes under the simultaneous protocol, after mastering 0, 1, or 5 conditional relations between C and other abstract stimuli (V, W, X, Y, Z) that were not included in the to-be-formed classes (ABCDE). Participants in the GR-many group attempted to form classes that contained four abstract stimuli and one meaningful picture as the C stimulus. In the GR-0, GR-1, GR-5, and GR-many groups, classes were formed by 17, 25, 58, and 67% of participants, respectively. Thus, likelihood of class formation was enhanced by the prior formation of five C-based conditional relations (the GR-5 vs. GR-0 condition), or the inclusion of a meaningful stimulus as a class member (the GR-many vs. GR-0 condition). The GR-5 and GR-many conditions produced very similar yields, indicating that class formation was enhanced to a similar degree by including a meaningful stimulus or an abstract stimulus that had become a member of five conditional relations prior to equivalence class formation. Finally, the low and high yields produced by the GR-1 and GR-5 conditions showed that the class enhancement effect of the GR-5 condition was due to the number of conditional relations established during preliminary training and not to the sheer amount of reinforcement provided while learning these conditional relations. Class enhancement produced by meaningful stimuli, then, can be attributed to their acquired conditional discriminative functions as well as their discriminative, connotative, and denotative properties.

  10. An Exploration of Responses to Drug Conditioned Stimuli during Treatment for Substance Dependence

    Directory of Open Access Journals (Sweden)

    Benjamin Goddard

    2013-01-01

    Full Text Available Although it is well established that drug conditioned stimuli produce a variety of conditioned responses, it is not known whether such stimuli can also reinforce an arbitrary operant response and thus serve as conditioned reinforcers. Volunteers (n=39 recruited from a residential treatment center for substance dependence were tested on a task in which presses on computer keys activated images of drugs/drug paraphernalia on a progressive ratio schedule of reinforcement. They also completed a personalized craving questionnaire and a personalized Implicit Association Test. A significant bias in responding was found for images of preferred drugs/route of drug administration. Craving, however, was low and the images generated negative evaluative reactions. Two additional studies were performed to ascertain the generalizability of the effects to a different population of drug-using individuals (i.e., students who drink and to incentive stimuli of a different nature (i.e., sexual. The additional studies partially replicated and extended the central findings of the main study. Therefore, although these data should be considered preliminary in light of small group sizes, it is concluded that cue specificity and availability of the unconditioned stimuli (drugs and sex plays a role in modulating responding maintained by conditioned reinforcers.

  11. Conditioning with compound stimuli in Drosophila melanogaster in the flight simulator.

    Science.gov (United States)

    Brembs, B; Heisenberg, M

    2001-08-01

    Short-term memory in Drosophila melanogaster operant visual learning in the flight simulator is explored using patterns and colours as a compound stimulus. Presented together during training, the two stimuli accrue the same associative strength whether or not a prior training phase rendered one of the two stimuli a stronger predictor for the reinforcer than the other (no blocking). This result adds Drosophila to the list of other invertebrates that do not exhibit the robust vertebrate blocking phenomenon. Other forms of higher-order learning, however, were detected: a solid sensory preconditioning and a small second-order conditioning effect imply that associations between the two stimuli can be formed, even if the compound is not reinforced.

  12. The Lurking Snake in the Grass: Interference of Snake Stimuli in Visually Taxing Conditions

    Directory of Open Access Journals (Sweden)

    Sandra Cristina Soares

    2012-04-01

    Full Text Available Based on evolutionary considerations, it was hypothesized that humans have been shaped to easily spot snakes in visually cluttered scenes that might otherwise hide camouflaged snakes. This hypothesis was tested in a visual search experiment in which I assessed automatic attention capture to evolutionarily-relevant distractor stimuli (snakes, in comparison with another animal which is also feared but where this fear has a disputed evolutionary origin (spiders, and neutral stimuli (mushrooms. Sixty participants were engaged in a task that involved the detection of a target (a bird among pictures of fruits. Unexpectedly, on some trials, a snake, a spider, or a mushroom replaced one of the fruits. The question of interest was whether the distracting stimuli slowed the reaction times for finding the target (the bird to different degrees. Perceptual load of the task was manipulated by increments in the set size (6 or 12 items on different trials. The findings showed that snake stimuli were processed preferentially, particularly under conditions where attentional resources were depleted, which reinforced the role of this evolutionarily-relevant stimulus in accessing the visual system (Isbell, 2009.

  13. Purkinje cell activity during classical conditioning with different conditional stimuli explains central tenet of Rescorla–Wagner model [corrected].

    Science.gov (United States)

    Rasmussen, Anders; Zucca, Riccardo; Johansson, Fredrik; Jirenhed, Dan-Anders; Hesslow, Germund

    2015-11-10

    A central tenet of Rescorla and Wagner's model of associative learning is that the reinforcement value of a paired trial diminishes as the associative strength between the presented stimuli increases. Despite its fundamental importance to behavioral sciences, the neural mechanisms underlying the model have not been fully explored. Here, we present findings that, taken together, can explain why a stronger association leads to a reduced reinforcement value, within the context of eyeblink conditioning. Specifically, we show that learned pause responses in Purkinje cells, which trigger adaptively timed conditioned eyeblinks, suppress the unconditional stimulus (US) signal in a graded manner. Furthermore, by examining how Purkinje cells respond to two distinct conditional stimuli and to a compound stimulus, we provide evidence that could potentially help explain the somewhat counterintuitive overexpectation phenomenon, which was derived from the Rescorla-Wagner model.

  14. Incentive learning for morphine-associated stimuli during protracted abstinence increases conditioned drug preference.

    Science.gov (United States)

    Smith, Rachel J; Aston-Jones, Gary

    2014-01-01

    Previous studies from our laboratory found that rats express increased preference for drug-paired stimuli following 2 or 5 weeks of protracted abstinence from chronic drug exposure as compared with naive animals. Here, we show that this increased morphine place preference depends upon experiencing drug-stimulus pairings specifically in the abstinent state, indicating a critical role for incentive learning. Male Sprague Dawley rats were initially conditioned for morphine place preference (8 mg/kg) and then made dependent on morphine (by subcutaneous morphine pellets) and subjected to forced abstinence. Place preference was tested every 1-2 weeks with no additional drug-cue conditioning. In this paradigm, there was no difference between morphine-pelleted (dependent) and placebo-pelleted (non-dependent) rats in place preference at any time during abstinence (up to 6 weeks). However, these same morphine-pelleted rats expressed significantly increased preference when they were subsequently re-conditioned for morphine place preference during protracted abstinence. Placebo-pelleted rats did not show enhanced preference after re-conditioning. These findings reveal that incentive learning has a key role in increased morphine place preference when drug is experienced during protracted abstinence. This indicates that incentive learning is involved not only in instrumental responding (as previously reported), but also in updating Pavlovian-conditioned responses to morphine-associated stimuli. Therefore, enhanced morphine preference is not a direct consequence of the negative affective state of abstinence, but instead reflects increased acquisition of morphine-stimulus associations during abstinence. These results indicate that, during the development of addiction in humans, drug-associated stimuli acquire increasingly stronger incentive properties each time they are re-experienced.

  15. Unequal associative changes when excitors and neutral stimuli are conditioned in compound.

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    Rescorla, R A

    2001-02-01

    In four experiments a compound of a previously conditioned excitor and a neutral stimulus was either reinforced with food or nonreinforced. Two experiments used a magazine approach procedure in rats, and two used an autoshaping procedure in pigeons. All experiments employed a novel compound test procedure, which permitted evaluation of the size of the associative change that took place for the excitatory and neutral stimuli. Reinforcement of the compound resulted in greater increments in the associative strength of the neutral stimulus than of the excitor. Nonreinforcement of the compound resulted in greater decrements in the associative strength of the excitor than of the neutral stimulus. These results agree with earlier experiments with compounds of excitors and inhibitors and provide an additional challenge to contemporary error-correction models of conditioning.

  16. How does not responding to appetitive stimuli cause devaluation: Evaluative conditioning or response inhibition?

    Science.gov (United States)

    Chen, Zhang; Veling, Harm; Dijksterhuis, Ap; Holland, Rob W

    2016-12-01

    In a series of 6 experiments (5 preregistered), we examined how not responding to appetitive stimuli causes devaluation. To examine this question, a go/no-go task was employed in which appetitive stimuli were consistently associated with cues to respond (go stimuli), or with cues to not respond (either no-go cues or the absence of cues; no-go stimuli). Change in evaluations of no-go stimuli was compared to change in evaluations of both go stimuli and of stimuli not presented in the task (untrained stimuli). Experiments 1 to 3 show that not responding to appetitive stimuli in a go/no-go task causes devaluation of these stimuli regardless of the presence of an explicit no-go cue. Experiments 4a and 4b show that the devaluation effect of appetitive stimuli is contingent on the percentage of no-go trials; devaluation appears when no-go trials are rare, but disappears when no-go trials are frequent. Experiment 5 shows that simply observing the go/no-go task does not lead to devaluation. Experiment 6 shows that not responding to neutral stimuli does not cause devaluation. Together, these results suggest that devaluation of appetitive stimuli by not responding to them is the result of response inhibition. By employing both go stimuli and untrained stimuli as baselines, alternative explanations are ruled out, and apparent inconsistencies in the literature are resolved. These experiments provide new theoretical insight into the relation between not responding and evaluation, and can be applied to design motor response training procedures aimed at changing people's behavior toward appetitive stimuli. (PsycINFO Database Record

  17. How does not responding to appetitive stimuli cause devaluation: Evaluative conditioning or response inhibition?

    NARCIS (Netherlands)

    Chen, Z.; Veling, H.P.; Dijksterhuis, A.J.; Holland, R.W.

    2016-01-01

    In a series of 6 experiments (5 preregistered), we examined how not responding to appetitive stimuli causes devaluation. To examine this question, a go/no-go task was employed in which appetitive stimuli were consistently associated with cues to respond (go stimuli), or with cues to not respond

  18. How does not responding to appetitive stimuli cause devaluation: Evaluative conditioning or response inhibition?

    NARCIS (Netherlands)

    Chen, Z.; Veling, H.P.; Dijksterhuis, A.J.; Holland, R.W.

    2016-01-01

    In a series of 6 experiments (5 preregistered), we examined how not responding to appetitive stimuli causes devaluation. To examine this question, a go/no-go task was employed in which appetitive stimuli were consistently associated with cues to respond (go stimuli), or with cues to not respond (eit

  19. Modeling processes in the acquisition of fears: vicarious electrodermal conditioning to fear-relevant stimuli.

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    Hygge, S; Ohman, A

    1978-03-01

    Fear-relevant (snakes, spiders, and rats) and fear-irrelevant (flowers, mushrooms, and berries) pictures were compared as conditioned and instigating stimuli in a vicarious classical conditioning paradigm with skin conductance responses as the dependent variable. A female confederate model and subject watched the pictures side by side. A female stimulus presentations, the experimenter interrupted to investigate alleged overreactions of the model to one of the stimulus classes. The model then vividly described a phobia for this object, which was to serve as a vicarious instigating stimulus. The experiment continued for a few conditioning trials, and then the experimenter announced that the disturbing stimulus would be omitted before the second part of the experiment. There was no effect of stimulus content on vicariously instigated responses, although significant overall instigation was observed. However, the responses to the stimulus that was paired with the model's phobic stimulus, that is, the vicariously conditioned responses, failed to extinguish during the second part of the experiment when it was fear-relevant but extinguished immediately when it was fear-irrelevant.

  20. Painful conditioning stimuli of the craniofacial region evokes diffuse noxious inhibitory controls in men and women.

    Science.gov (United States)

    Wang, Kelun; Svensson, Peter; Sessle, Barry J; Cairns, Brian E; Arendt-Nielsen, Lars

    2010-01-01

    To compare the modulatory effects of tonic mechanical or thermal craniofacial painful conditioning stimuli on pain sensitivity in craniofacial and spinal test sites in healthy men and women. Mechanical and cold headbands were developed and tested on 12 healthy men and 12 age-matched women (mean +/- SEM: 27 +/- 1.5 years). The pressure applied by the mechanical headband around the skull above the eyebrows could be adjusted over time via feedback from a 0 to 10 electronic visual analog scale (VAS) to maintain the pain intensity at a given level for 10 minutes (3 to 7 on VAS). The cold headband consisted of a series of plastic bags filled with antifreeze water having a temperature of approx 3 degrees C. During the 10 minutes of application, the subjects were asked to rate the pain intensity on a 10-cm VAS. Pressure pain thresholds (PPT) were recorded over the right and left masseter muscles (MAR, MAL), right splenius muscle (neck), right elbow (elbow), and right middle finger (finger) by a pressure algometer (1-cm2 area probe). The PPTs at each of the five sites were determined at baseline and during the mechanical or cold-induced pain. The two sessions with mechanical or cold headbands were performed at an interval of 30 minutes. Women had significantly lower absolute PPT values than men at most test sites (Unpaired t-test: P cold headband caused pain in both men (4.0 +/- 0.4 cm) and women (4.5 +/- 0.4 cm) (P = .285). During the cold-induced pain, a significant PPT elevation was found at all test sites in men (P .446). This study has documented that mechanical and thermal painful tonic stimuli applied to the craniofacial region can evoke diffuse noxious inhibitory control (DNIC)-like effects in the craniofacial region as well as spinally innervated areas, but without sex differences.

  1. Exponential reduction of finite volume effects with twisted boundary conditions

    CERN Document Server

    Cherman, Aleksey; Wagman, Michael L; Yaffe, Laurence G

    2016-01-01

    Flavor-twisted boundary conditions can be used for exponential reduction of finite volume artifacts in flavor-averaged observables in lattice QCD calculations with $SU(N_f)$ light quark flavor symmetry. Finite volume artifact reduction arises from destructive interference effects in a manner closely related to the phase averaging which leads to large $N_c$ volume independence. With a particular choice of flavor-twisted boundary conditions, finite volume artifacts for flavor-singlet observables in a hypercubic spacetime volume are reduced to the size of finite volume artifacts in a spacetime volume with periodic boundary conditions that is four times larger.

  2. Reinforcement and the Organization of Behavior in Golden Hamsters: Pavlovian Conditioning with Food and Shock Unconditioned Stimuli

    Science.gov (United States)

    Shettleworth, Sara J.

    1978-01-01

    There has been considerable interest lately in cases where instrumental conditionability appears to depend on the reinforcer used. Here the effects of Pavlovian conditioned stimuli (CSs)on golden hamster behaviors was observed. The intent was to see whether previously reported differences among the behaviors produced by food reinforcement and…

  3. Comparison of volume-selective z-shim and conventional EPI in fMRI studies using face stimuli

    CERN Document Server

    Fukunaga, Hu Cheng Srikanth Padmala Rena

    2013-01-01

    Single-shot gradient recalled echo planar imaging (EPI) is the primary tool for functional magnetic resonance imaging (fMRI). The image often suffers from signal drop near the air-tissue interface, such as the amygdala and regions of the orbitofrontal lobe. An effective way to correct for this type of artifact is by applying multi-shot EPI using different z-shimming. Unfortunately, the scanning efficiency is significantly lowered. More recently, a new technique called volume-selective z-shim was proposed to implement z-shim compensation to only specific slices with large susceptibility effects. The high imaging efficiency of volume selective z-shim makes it possible to substitute conventional EPI for whole brain studies. In this study two fMRI experiments were conducted to compare volume- selective z-shim and conventional EPI while subjects performed tasks on face stimuli. The comparison was focused on three brain regions: amygdala, hippocampus, and fusiform gyrus. Our results indicate that despite fewer volu...

  4. A pragmatic comparison of noise burst and electric shock unconditioned stimuli for fear conditioning research with many trials.

    Science.gov (United States)

    Sperl, Matthias F J; Panitz, Christian; Hermann, Christiane; Mueller, Erik M

    2016-09-01

    Several methods that are promising for studying the neurophysiology of fear conditioning (e.g., EEG, MEG) require a high number of trials to achieve an adequate signal-to-noise ratio. While electric shock and white noise burst are among the most commonly used unconditioned stimuli (US) in conventional fear conditioning studies with few trials, it is unknown whether these stimuli are equally well suited for paradigms with many trials. Here, N = 32 participants underwent a 260-trial differential fear conditioning and extinction paradigm with a 240-trial recall test 24 h later and neutral faces as conditioned stimuli. In a between-subjects design, either white noise bursts (n = 16) or electric shocks (n = 16) served as US, and intensities were determined using the most common procedure for each US (i.e., a fixed 95 dB noise burst and a work-up procedure for electric shocks, respectively). In addition to differing US types, groups also differed in closely linked US-associated characteristics (e.g., calibration methods, stimulus intensities, timing). Subjective ratings (arousal/valence), skin conductance, and evoked heart period changes (i.e., fear bradycardia) indicated more reliable, extinction-resistant, and stable conditioning in the white noise burst versus electric shock group. In fear conditioning experiments where many trials are presented, white noise burst should serve as US.

  5. Clustering Words to Match Conditions: An Algorithm for Stimuli Selection in Factorial Designs

    Science.gov (United States)

    Guasch, Marc; Haro, Juan; Boada, Roger

    2017-01-01

    With the increasing refinement of language processing models and the new discoveries about which variables can modulate these processes, stimuli selection for experiments with a factorial design is becoming a tough task. Selecting sets of words that differ in one variable, while matching these same words into dozens of other confounding variables…

  6. Acute and Conditioned Blood Pressure Changes in Relation to Social and Psychosocial Stimuli in Rats

    NARCIS (Netherlands)

    Fokkema, Dirk S.; Koolhaas, Jaap M.

    1985-01-01

    The naturally occurring tendency to compete with other rats for territorial space has been used to study individual behavior characteristics and blood pressure reactivity to social stimuli in adult male TMD-S3 rats. The competitive characteristics of the individual rats are consistent in two differe

  7. Replay of conditioned stimuli during late REM and stage N2 sleep influences affective tone rather than emotional memory strength.

    Science.gov (United States)

    Rihm, Julia S; Rasch, Björn

    2015-07-01

    Emotional memories are reprocessed during sleep, and it is widely assumed that this reprocessing occurs mainly during rapid eye movement (REM) sleep. In support for this notion, vivid emotional dreams occur mainly during REM sleep, and several studies have reported emotional memory enhancement to be associated with REM sleep or REM sleep-related parameters. However, it is still unknown whether reactivation of emotional memories during REM sleep strengthens emotional memories. Here, we tested whether re-presentation of emotionally learned stimuli during REM sleep enhances emotional memory. In a split-night design, participants underwent Pavlovian conditioning after the first half of the night. Neutral sounds served as conditioned stimuli (CS) and were either paired with a negative odor (CS+) or an odorless vehicle (CS-). During sound replay in subsequent late REM or N2 sleep, half of the CS+ and half of the CS- were presented again. In contrast to our hypothesis, replay during sleep did not affect emotional memory as measured by the differentiation between CS+ and CS- in expectancy, arousal and valence ratings. However, replay unspecifically decreased subjective arousal ratings of both emotional and neutral sounds and increased positive valence ratings also for both CS+ and CS- sounds, respectively. These effects were slightly more pronounced for replay during REM sleep. Our results suggest that re-exposure to previously conditioned stimuli during late sleep does not affect emotional memory strength, but rather influences the affective tone of both emotional and neutral memories.

  8. Elevated Fear Conditioning to Socially Relevant Unconditioned Stimuli in Social Anxiety Disorder

    National Research Council Canada - National Science Library

    Pine, Daniel S; Grillon, Christian; Biggs, Arter L; Johnson, Linda L; Levenson, Jessica; Lissek, Shmuel; Ameli, Rezvan

    2008-01-01

    Objective: Though conditioned fear has long been acknowledged as an important etiologic mechanism in social anxiety disorder, past psychophysiological experiments have found no differences in general...

  9. Avoided by association: acquisition, extinction, and renewal of avoidance tendencies toward conditioned fear stimuli

    NARCIS (Netherlands)

    A.M. Krypotos; M. Effting; I. Arnaudova; M. Kindt; T. Beckers

    2013-01-01

    Traditional theoretical models hold that avoidance reflects the interplay of Pavlovian and instrumental learning. Here we suggest that avoidance tendencies to intrinsically neutral cues may be established by mere Pavlovian association. Following fear conditioning, in which pictures of one object wer

  10. Unconscious classical conditioning of sexual arousal: Evidence for the conditioning of female genital arousal to subliminally presented sexual stimuli

    NARCIS (Netherlands)

    S. Both; M. Spiering; E. Laan; S. Balcome; B. van den Heuvel; W. Everaerd

    2008-01-01

    Introduction. Although the assumption that sexual behavior is at least partly learned is common across theories of sexual behavior, classical conditioning of sexual response in women has been seldom studied. Aim. The study of unconscious classical conditioning of appetitive sexual responses in women

  11. Conditioned preference for sweet stimuli in OLETF rat: effects of food deprivation.

    Science.gov (United States)

    De Jonghe, Bart C; Hajnal, Andras; Covasa, Mihai

    2007-05-01

    The Otsuka Long-Evans Tokushima Fatty (OLETF) rat, an outbred strain of Long- Evans Tokushima Otsuka rat (LETO) that lacks CCK-1 receptor expression, is hyperphagic and develops obesity and type-2 diabetes. The present study sought to assess how OLETF rats alter intake, preference, and conditioned preference of palatable solutions after acute food deprivation. Our results show that after 24 h chow restriction, LETO rats increase both sucrose intake and two-bottle sucrose preference relative to their free-fed baseline, whereas OLETF rats do not increase sucrose intake (0.3 M or 1.0 M sucrose) or preference (1.0 M vs. 0.3 M sucrose) when they are food deprived. In contrast, OLETF rats exhibit a higher conditioned flavor preference when sucrose is used as unconditioned stimulus (US) relative to LETO rats, whether overnight food restricted (81% vs. 71% for OLETF and LETO rats, respectively) or free fed (82% vs. 54% for OLETF and LETO rats, respectively) during the test. When a noncaloric saccharin solution is used as US, OLETF rats show a higher preference for the saccharin-associated flavor relative to LETO rats when nondeprived (76% vs. 58% for OLETF and LETO rats, respectively); however, neither strain shows differential conditioned flavor preference for saccharin in the deprivation state during the test. These findings suggest that OLETF rats fail to integrate postabsorptive and orosensory effects of sucrose in a conditioning setting to influence intake. Thus, it appears that OLETF rats form preferences for sucrose based largely on orosensory and hedonic properties of the solution, rather than caloric value.

  12. A method for closed-loop presentation of sensory stimuli conditional on the internal brain-state of awake animals.

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    Rutishauser, Ueli; Kotowicz, Andreas; Laurent, Gilles

    2013-04-30

    Brain activity often consists of interactions between internal-or on-going-and external-or sensory-activity streams, resulting in complex, distributed patterns of neural activity. Investigation of such interactions could benefit from closed-loop experimental protocols in which one stream can be controlled depending on the state of the other. We describe here methods to present rapid and precisely timed visual stimuli to awake animals, conditional on features of the animal's on-going brain state; those features are the presence, power and phase of oscillations in local field potentials (LFP). The system can process up to 64 channels in real time. We quantified its performance using simulations, synthetic data and animal experiments (chronic recordings in the dorsal cortex of awake turtles). The delay from detection of an oscillation to the onset of a visual stimulus on an LCD screen was 47.5ms and visual-stimulus onset could be locked to the phase of ongoing oscillations at any frequency ≤40Hz. Our software's architecture is flexible, allowing on-the-fly modifications by experimenters and the addition of new closed-loop control and analysis components through plugins. The source code of our system "StimOMatic" is available freely as open-source.

  13. Enhanced D1 and D2 inhibitions induced by low-frequency trains of conditioning stimuli: differential effects on H- and T-reflexes and possible mechanisms.

    Science.gov (United States)

    Mezzarane, Rinaldo André; Magalhães, Fernando Henrique; Chaud, Vitor Martins; Elias, Leonardo Abdala; Kohn, André Fabio

    2015-01-01

    Mechanically evoked reflexes have been postulated to be less sensitive to presynaptic inhibition (PSI) than the H-reflex. This has implications on investigations of spinal cord neurophysiology that are based on the T-reflex. Preceding studies have shown an enhanced effect of PSI on the H-reflex when a train of ~10 conditioning stimuli at 1 Hz was applied to the nerve of the antagonist muscle. The main questions to be addressed in the present study are if indeed T-reflexes are less sensitive to PSI and whether (and to what extent and by what possible mechanisms) the effect of low frequency conditioning, found previously for the H-reflex, can be reproduced on T-reflexes from the soleus muscle. We explored two different conditioning-to-test (C-T) intervals: 15 and 100 ms (corresponding to D1 and D2 inhibitions, respectively). Test stimuli consisted of either electrical pulses applied to the posterior tibial nerve to elicit H-reflexes or mechanical percussion to the Achilles tendon to elicit T-reflexes. The 1 Hz train of conditioning electrical stimuli delivered to the common peroneal nerve induced a stronger effect of PSI as compared to a single conditioning pulse, for both reflexes (T and H), regardless of C-T-intervals. Moreover, the conditioning train of pulses (with respect to a single conditioning pulse) was proportionally more effective for T-reflexes as compared to H-reflexes (irrespective of the C-T interval), which might be associated with the differential contingent of Ia afferents activated by mechanical and electrical test stimuli. A conceivable explanation for the enhanced PSI effect in response to a train of stimuli is the occurrence of homosynaptic depression at synapses on inhibitory interneurons interposed within the PSI pathway. The present results add to the discussion of the sensitivity of the stretch reflex pathway to PSI and its functional role.

  14. VOLUME DEFECT FATIGUE FAILURE OF CERAMIC BALLS UNDER ROLLING CONDITION

    Institute of Scientific and Technical Information of China (English)

    ZHOU Jingling; WU Guoqing; CHEN Xiaoyang

    2007-01-01

    A newly developed pure rolling fatigue test rig with three contact points is used to test the rolling contact fatigue properties of silicon nitride ceramic balls. Ball surfaces are examined after failure with optical microscopy and scanning electron microscopy. The failure cause, fatigue phenomenon and mechanics are analyzed. The research shows that subsurface cracks play a dominant role in the formation of spalling failure. These cracks originated from volume defects of the material and propagate, to form elliptical fatigue spalls under the action of principal tensile stresses. The principal tensile stress increases with increasing contact load, causing spall formation and reduction of rolling contact life. The greater the principal tensile stress is, the more severe the peeling of near surface is. Under the same condition, the closer volume defects are to the surface, the more likely failure occurs, the shorter the rolling contact life is.

  15. Behavioral determination of stimulus pair discrimination of auditory acoustic and electrical stimuli using a classical conditioning and heart-rate approach.

    Science.gov (United States)

    Morgan, Simeon J; Paolini, Antonio G

    2012-06-06

    Acute animal preparations have been used in research prospectively investigating electrode designs and stimulation techniques for integration into neural auditory prostheses, such as auditory brainstem implants and auditory midbrain implants. While acute experiments can give initial insight to the effectiveness of the implant, testing the chronically implanted and awake animals provides the advantage of examining the psychophysical properties of the sensations induced using implanted devices. Several techniques such as reward-based operant conditioning, conditioned avoidance, or classical fear conditioning have been used to provide behavioral confirmation of detection of a relevant stimulus attribute. Selection of a technique involves balancing aspects including time efficiency (often poor in reward-based approaches), the ability to test a plurality of stimulus attributes simultaneously (limited in conditioned avoidance), and measure reliability of repeated stimuli (a potential constraint when physiological measures are employed). Here, a classical fear conditioning behavioral method is presented which may be used to simultaneously test both detection of a stimulus, and discrimination between two stimuli. Heart-rate is used as a measure of fear response, which reduces or eliminates the requirement for time-consuming video coding for freeze behaviour or other such measures (although such measures could be included to provide convergent evidence). Animals were conditioned using these techniques in three 2-hour conditioning sessions, each providing 48 stimulus trials. Subsequent 48-trial testing sessions were then used to test for detection of each stimulus in presented pairs, and test discrimination between the member stimuli of each pair. This behavioral method is presented in the context of its utilisation in auditory prosthetic research. The implantation of electrocardiogram telemetry devices is shown. Subsequent implantation of brain electrodes into the Cochlear

  16. Frontal brain activity and behavioral indicators of affective states are weakly affected by thermal stimuli in sheep living in different housing conditions

    Directory of Open Access Journals (Sweden)

    Sabine eVögeli

    2015-05-01

    Full Text Available Many stimuli evoke short-term emotional reactions. These reactions may play an important role in assessing how a subject perceives a stimulus. Additionally, long-term mood may modulate the emotional reactions but it is still unclear in what way. The question seems to be important in terms of animal welfare, as a negative mood may taint emotional reactions. In the present study with sheep, we investigated the effects of thermal stimuli on emotional reactions and the potential modulating effect of mood induced by manipulations of the housing conditions. We assume that unpredictable, stimulus-poor conditions lead to a negative and predictable, stimulus-rich conditions to a positive mood state. The thermal stimuli were applied to the upper breast during warm ambient temperatures: hot (as presumably negative, intermediate, and cold (as presumably positive. We recorded cortical activity by functional near-infrared spectroscopy, restlessness behavior (e.g. locomotor activity, aversive behaviors and ear postures as indicators of emotional reactions. The strongest hemodynamic reaction was found during a stimulus of intermediate valence independent of the animal’s housing conditions, whereas locomotor activity, ear movements and aversive behaviors were seen most in sheep from the unpredictable, stimulus-poor housing conditions, independent of stimulus valence. We conclude that, sheep perceived the thermal stimuli and differentiated between some of them. An adequate interpretation of the neuronal activity pattern remains difficult, though. The effects of housing conditions were small indicating that the induction of mood was only modestly efficacious. Therefore, a modulating effect of mood on the emotional reaction was not found.

  17. Color-specific conditioning effects due to both orange and blue stimuli are observed in a Halobacterium salinarum strain devoid of putative methylatable sites on HtrI.

    Science.gov (United States)

    Lucia, S; Cercignani, G; Frediani, A; Petracchi, D

    2003-01-01

    Behavioral responses of Halobacterium salinarum appear as changes in the frequency of motion reversals. Turning on orange light decreases the reversal frequency, whereas blue light induces reversals. Light pulses normally induce the same response as step-up stimuli. However, anomalous behavioral reactions, including inverse responses, are seen when stimuli are applied in sequence. The occurrence of a prior stimulus is conditioning for successive stimulation on a time scale of the same order of adaptational processes. These prolonged conditioning effects are color-specific. The only adaptation process identified so far is methylation of the transducers, and this could be somehow color-specific. Therefore we tested for the behavioral anomalies in a mutant in which all methylation sites on the transducer have been eliminated. The results show that behavioral anomalies are unaffected by the absence of methylation processes on the transducer.

  18. Pavlovian conditioning of emotional responses to olfactory and contextual stimuli: a potential model for the development and expression of chemical intolerance.

    Science.gov (United States)

    Otto, T; Giardino, N D

    2001-03-01

    Chemical intolerance (CI) in humans is a poorly understood phenomenon of uncertain etiology, seemingly influenced by multiple factors both within and between affected individuals. Several authors have suggested that the development of CI in some individuals may be due, at least in part, to Pavlovian conditioning processes in which the expression of overt symptoms to certain substances reflects classically conditioned responses to previously neutral olfactory and contextual stimuli. In this paper, we describe the potential relationship between olfactory and contextual conditioning in experimental animals and the development and expression of CI in humans. Furthermore, as significant advances have been made in delineating the brain areas that underlie these learned responses, we also review recent research on the contributions of the amygdala and perirhinal cortical region to olfactory and contextual fear conditioning.

  19. Generalized Navier Boundary Condition for a Volume Of Fluid approach using a Finite-Volume method

    CERN Document Server

    Boelens, A M P

    2016-01-01

    In this work, an analytical Volume Of Fluid (VOF) implementation of the Generalized Navier Boundary Condition is presented based on the Brackbill surface tension model. The model is validated by simulations of droplets on a smooth surface in a planar geometry. Looking at the static behavior of the droplets, it is found that there is a good match between the droplet shape resolved in the simulations and the theoretically predicted shape for various values of the Young's angle. Evaluating the spreading of a droplet on a completely wetting surface, the Voinov-Tanner-Cox law ($\\theta \\propto \\text{Ca}^{1/3}$) can be observed. At later times scaling follows $r \\propto t^{1/2}$, suggesting spreading is limited by inertia. These observations are made without any fitting parameters except the slip length.

  20. The Role of Nucleus Accumbens Shell in Learning about Neutral versus Excitatory Stimuli during Pavlovian Fear Conditioning

    Science.gov (United States)

    Bradfield, Laura A.; McNally, Gavan P.

    2010-01-01

    We studied the role of nucleus accumbens shell (AcbSh) in Pavlovian fear conditioning. Rats were trained to fear conditioned stimulus A (CSA) in Stage I, which was then presented in compound with a neutral stimulus and paired with shock in Stage II. AcbSh lesions had no effect on fear-learning to CSA in Stage I, but selectively prevented learning…

  1. [Testing of the effect of classic conditioning stimuli in human experiment by means of the transfer of control paradigm].

    Science.gov (United States)

    Wolter, J

    1999-01-01

    Pavlovian conditioning in animals is often evaluated by means of transfer of control experiments. With human subjects, however, only very few studies have been conducted and the outcomes were often not in accordance with theoretical explanations based on studies with animals. A theoretical framework is presented that tries to integrate the results of the human conditioning paradigm and the animal conditioning paradigm as well, with reference to the well-known Yerkes-Dodson law. The experimental study with human subjects (N = 24) confirmed the predictions out of this framework, when a procedure similar to animal research is applied.

  2. Classical Conditioning Components of the Orienting Reflex to Words Using Innocuous and Noxious Unconditioned Stimuli Under Different Conditioned Stimulus-Unconditioned Stimulus Intervals

    Science.gov (United States)

    Maltzman, Irving; And Others

    1977-01-01

    Concerns the examination of conditioned stimulus--unconditioned stimulus (CS--UCS) intervals of different lengths. Demonstrates the feasibility of using a forewarned reaction time procedure with an innocuous imperative stimulus for the investigation of classical conditioning. (Editor/RK)

  3. Effect of varying the intensity and train frequency of forelimb and cerebellar mossy fiber conditioned stimuli on the latency of conditioned eye-blink responses in decerebrate ferrets.

    Science.gov (United States)

    Svensson, P; Ivarsson, M; Hesslow, G

    1997-01-01

    To study the role of the mossy fiber afferents to the cerebellum in classical eye-blink conditioning, in particular the timing of the conditioned responses, we compared the effects of varying a peripheral conditioned stimulus with the effects of corresponding variations of direct stimulation of the mossy fibers. In one set of experiments, decerebrate ferrets were trained in a Pavlovian eye-blink conditioning paradigm with electrical forelimb train stimulation as conditioned stimulus and electrical periorbital stimulation as the unconditioned stimulus. When stable conditioning had been achieved, the effect of increasing the intensity or frequency of the forelimb stimulation was tested. By increasing the intensity from 1 to 2 mA, or the train frequency from 50 to 100 Hz, an immediate decrease was induced in both the onset latency and the latency to peak of the conditioned response. If the conditioned stimulus intensity/frequency was maintained at the higher level, the response latencies gradually returned to preshift values. In a second set of experiments, the forelimb stimulation was replaced by direct train stimulation of the middle cerebellar peduncle as conditioned stimulus. Varying the frequency of the stimulus train between 50 and 100 Hz had effects that were almost identical to those obtained when using a forelimb conditioned stimulus. The functional meaning of the latency effect is discussed. It is also suggested that the results support the view that the conditioned stimulus is transmitted through the mossy fibers and that the mechanism for timing the conditioned response is situated in the cerebellum.

  4. The paraventricular nucleus of the thalamus is differentially recruited by stimuli conditioned to the availability of cocaine versus palatable food.

    Science.gov (United States)

    Matzeu, Alessandra; Cauvi, Gabrielle; Kerr, Tony M; Weiss, Friedbert; Martin-Fardon, Rémi

    2017-01-01

    The paraventricular nucleus of the thalamus (PVT) is not traditionally considered part of the brain addiction neurocircuitry but has received growing attention with regard to a role in the modulation of drug-seeking behavior. This study sought to establish the pattern of neural activation induced by a response-reinstating discriminative stimulus (S(D) ) conditioned to either cocaine (COC) or a conventional reinforcer using a palatable food substance, sweetened condensed milk (SCM). Male Wistar rats were trained to associate one S(D) (S(+) ; COC or SCM availability) and a distinctly different S(D) (S(-) ; non-reward; i.e. the availability of saline or the absence of SCM). Following extinction of COC- and SCM-reinforced responding, rats were presented with the respective S(+) or S(-) alone and tested for the reinstatement of reward seeking. The COC S(+) and SCM S(+) elicited identical reinstatement, whereas the non-reward S(-) was behaviorally ineffective. PVT sections were obtained following completion of the reinstatement tests and labeled for Fos. The number of Fos(+) neurons was compared among rats that were presented with the COC S(+) , SCM S(+) or S(-) . Rats that were presented with the COC S(+) exhibited a significant increase in Fos expression compared with rats that were presented with the S(-) . Moreover, Fos expression was significantly correlated with the number of reinstatement responses that were induced by the COC S(+) . In contrast, the SCM S(+) and S(-) produced identical increases in Fos expression, without behaviorally relevant correlations. The findings implicate the PVT as an important site that is selectively recruited during COC-seeking behavior.

  5. Stimuli-Sensitive Hydrogel Based on N-Isopropylacrylamide and Itaconic Acid for Entrapment and Controlled Release of Candida rugosa Lipase under Mild Conditions

    Directory of Open Access Journals (Sweden)

    Nikola Milašinović

    2014-01-01

    Full Text Available Stimuli responsive pH- and temperature-sensitive hydrogel drug delivery systems, as those based on N-isopropylacrylamide (NiPAAm and itaconic acid (IA, have been attracting much of the attention of the scientific community nowadays, especially in the field of drug release. By adjusting comonomer composition, the matrix is enabled to protect the incorporated protein in the highly acidic environment of upper gastrointestinal tract and deliver it in the neutral or slightly basic region of the lower intestine. The protein/poly(NiPAAm-co-IA hydrogels were synthetized by free radical crosslinking copolymerization and were characterized concerning their swelling capability, mechanical properties, and morphology. The pore structure and sizes up to 1.90 nm allowed good entrapment of lipase molecules. Model protein, lipase from Candida rugosa, was entrapped within hydrogels upon mild conditions that provided its protection from harmful environmental influences. The efficiency of the lipase entrapment reached 96.7%, and was dependent on the initial concentration of lipase solution. The swelling of the obtained hydrogels in simulated pH and temperature of gastrointestinal tract, the lipase entrapment efficiency, and its release profiles from hydrogels were investigated as well.

  6. Neurons in the pigeon caudolateral nidopallium differentiate Pavlovian conditioned stimuli but not their associated reward value in a sign-tracking paradigm

    Science.gov (United States)

    Kasties, Nils; Starosta, Sarah; Güntürkün, Onur; Stüttgen, Maik C.

    2016-01-01

    Animals exploit visual information to identify objects, form stimulus-reward associations, and prepare appropriate behavioral responses. The nidopallium caudolaterale (NCL), an associative region of the avian endbrain, contains neurons exhibiting prominent response modulation during presentation of reward-predicting visual stimuli, but it is unclear whether neural activity represents valuation signals, stimulus properties, or sensorimotor contingencies. To test the hypothesis that NCL neurons represent stimulus value, we subjected pigeons to a Pavlovian sign-tracking paradigm in which visual cues predicted rewards differing in magnitude (large vs. small) and delay to presentation (short vs. long). Subjects’ strength of conditioned responding to visual cues reliably differentiated between predicted reward types and thus indexed valuation. The majority of NCL neurons discriminated between visual cues, with discriminability peaking shortly after stimulus onset and being maintained at lower levels throughout the stimulus presentation period. However, while some cells’ firing rates correlated with reward value, such neurons were not more frequent than expected by chance. Instead, neurons formed discernible clusters which differed in their preferred visual cue. We propose that this activity pattern constitutes a prerequisite for using visual information in more complex situations e.g. requiring value-based choices. PMID:27762287

  7. Design and Verification Methodology of Boundary Conditions for Finite Volume Schemes

    Science.gov (United States)

    2012-07-01

    Finite Volume Schemes 5a. CONTRACT NUMBER In-House 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Folkner, D., Katz , A and Sankaran...July 9-13, 2012 ICCFD7-2012-1001 Design and Verification Methodology of Boundary Conditions for Finite Volume Schemes D. Folkner∗, A. Katz ∗ and V...Office (ARO), under the supervision of Dr. Frederick Ferguson. The authors would like to thank Dr. Ferguson for his continuing support of this research

  8. Experimental Investigation of Pressure-volume-Temperature Mass Gauging Method Under Microgravity Condition by Parabolic Flight

    Science.gov (United States)

    Seo, Mansu; Park, Hana; Yoo, DonGyu; Jung, Youngsuk; Jeong, Sangkwon

    Gauging the volume or mass of liquid propellant of a rocket vehicle in space is an important issue for its economic feasibility and optimized design of loading mass. Pressure-volume-temperature (PVT) gauging method is one of the most suitable measuring techniques in space due to its simplicity and reliability. This paper presents unique experimental results and analyses of PVT gauging method using liquid nitrogen under microgravity condition by parabolic flight. A vacuum-insulated and cylindrical-shaped liquid nitrogen storage tank with 9.2 L volume is manufactured by observing regulation of parabolic flight. PVT gauging experiments are conducted under low liquid fraction condition from 26% to 32%. Pressure, temperature, and the injected helium mass into the storage tank are measured to obtain the ullage volume by gas state equation. Liquid volume is finally derived by the measured ullage volume and the known total tank volume. Two sets of parabolic flights are conducted and each set is composed of approximately 10 parabolic flights. In the first set of flights, the short initial waiting time (3 ∼ 5 seconds) cannot achieve sufficient thermal equilibrium condition at the beginning. It causes inaccurate gauging results due to insufficient information of the initial helium partial pressure in the tank. The helium injection after 12 second waiting time at microgravity condition with high mass flow rate in the second set of flights achieves successful initial thermal equilibrium states and accurate measurement results of initial helium partial pressure. Liquid volume measurement errors in the second set are within 11%.

  9. Chiral Perturbation Theory at Finite Volume and/or with Twisted Boundary Conditions

    CERN Document Server

    Bijnens, Johan

    2016-01-01

    In this talk we discuss a number of ChPT calculations relevant for lattice QCD. These include the finite volume corrections at two-loop order for masses and decay constants. The second part is about hadronic vacuum polarization where we present the two-loop ChPT estimate for the disconnected and strange quark contributions. We also present the finite volume corrections at two-loop order. The final part is the one-loop finite volume with twisted boundary conditions contribution to $f_+(q^2)$ and the full $K_{\\ell3}$ amplitude

  10. Pseudoscalar mesons in a finite cubic volume with twisted boundary conditions

    Science.gov (United States)

    Colangelo, Gilberto; Vaghi, Alessio

    2016-07-01

    We study the effects of a finite cubic volume with twisted boundary conditions on pseudoscalar mesons. We first apply chiral perturbation theory in the p-regime and calculate the corrections for masses, decay constants, pseudoscalar coupling constants and form factors at next-to-leading order. We show that the Feynman-Hellmann theorem and the relevant Ward-Takahashi identity are satisfied. We then derive asymptotic formulae à la Lüscher for twisted boundary conditions. We show that chiral Ward identities for masses and decay constants are satisfied by the asymptotic formulae in finite volume as a consequence of infinite-volume Ward identities. Applying asymptotic formulae in combination with chiral perturbation theory we estimate corrections beyond next-to-leading order for twisted boundary conditions.

  11. Pseudoscalar mesons in a finite cubic volume with twisted boundary conditions

    CERN Document Server

    Colangelo, Gilberto

    2016-01-01

    We study the effects of a finite cubic volume with twisted boundary conditions on pseudoscalar mesons. We first apply chiral perturbation theory in the p-regime and calculate the corrections for masses, decay constants, pseudoscalar coupling constants and form factors at next-to-leading order. We show that the Feynman-Hellmann theorem and the relevant Ward-Takahashi identity are satisfied. We then derive asymptotic formulae a la Luscher for twisted boundary conditions. We show that chiral Ward identities for masses and decay constants are satisfied by the asymptotic formulae in finite volume as a consequence of infinite-volume Ward identities. Applying asymptotic formulae in combination with chiral perturbation theory we estimate corrections beyond next-to-leading order for twisted boundary conditions.

  12. Effects of volume fraction condition on thermodynamic restrictions in mixture theory

    Institute of Scientific and Technical Information of China (English)

    牛永红; 苗天德

    2002-01-01

    Volume fraction condition is a true constraint that must be taken into consideration in deducing the thermodynamic restrictions of mixture theory applying the axiom of dissipation. For a process to be admissible, the constraints imposed by the volume fraction condition include not only the equation obtained by taking its material derivative with respect to the motion of a given phase, but also those by taking its spatial gradient. The thermodynamic restrictions are deduced under the complete constraints, the results obtained are consistent for the mixtures with or without a compressible phase,and in which the free energy of each phase depends on the densities of all phases.

  13. The influence of speed and interval variation of serial stimuli on physiological change

    NARCIS (Netherlands)

    Kok, A.

    1970-01-01

    Studied changes in heart rate (HR), heart rate variability (HRV), blood volume pulse (BVP), respiration speed (RS), and alpha rhythm (AR) under conditions of the variation of the speed and intervals of auditory stimuli in a serial 2-choice response task. The analysis of variance of the percentage sc

  14. Influence of the turbinate volumes as measured by magnetic resonance imaging on nasal air conditioning.

    Science.gov (United States)

    Lindemann, Joerg; Tsakiropoulou, Evangelia; Vital, Victor; Keck, Tilman; Leiacker, Richard; Pauls, Sandra; Wacke, Florian; Wiesmiller, Kerstin M

    2009-01-01

    Changes in nasal airflow caused by varying intranasal volumes and cross-sectional areas affect the contact between air and surrounding mucosa entailing alterations in nasal air conditioning. This study evaluates the correlation between nasal air conditioning and the volumes of the inferior and middle turbinates as measured by magnetic resonance imaging (MRI). Fourteen healthy volunteers were enrolled. Each volunteer had been examined by rhinomanometry, acoustic rhinometry, intranasal air temperature, and humidity measurements at defined intranasal sites as well as MRI of the nasal cavity and the paranasal sinuses. The volumetric data of the turbinates was based on the volumetric software Amira. Comparable results were obtained regarding absolute humidity values and temperature values within the nasal valve area and middle turbinate area for both the right and the left side of the nasal cavity. No statistically significant differences were found in the rhinomanometric values and the acoustic rhinometry results of both sides (p > 0.05). No statistical correlations were found between the volumes of the inferior (mean, 6.1 cm3) and middle turbinate (mean, 1.8 cm3) and the corresponding humidity and temperature values. Additionally, the air temperature and humidity values did not correlate with the rhinometrical endonasal volumes (0-20 mm and 20-50 mm from the nasal entrance). The normal range of volumes of the inferior and middle turbinate does not seem to have a significant impact on intranasal air conditioning in healthy subjects. The exact limits where alterations of the turbinate volume negatively affect nasal air conditioning are still unknown.

  15. A formula to compute the microcanonical volume of reactive initial conditions in transition state theory

    NARCIS (Netherlands)

    Waalkens, H.; Burbanks, A.; Wiggins, S.

    2005-01-01

    We present the formal proof of a procedure to compute the phase-space volume of initial conditions for trajectories that, for a constant energy, escape or ‘react’ from a multi-dimensional potential well with one or several exit/entrance channels. The procedure relies on a phase-space formulation of

  16. A formula to compute the microcanonical volume of reactive initial conditions in transition state theory

    NARCIS (Netherlands)

    Waalkens, H.; Burbanks, A.; Wiggins, S.

    2005-01-01

    We present the formal proof of a procedure to compute the phase-space volume of initial conditions for trajectories that, for a constant energy, escape or ‘react’ from a multi-dimensional potential well with one or several exit/entrance channels. The procedure relies on a phase-space formulation of

  17. Pigeons prefer discriminative stimuli independently of the overall probability of reinforcement and of the number of presentations of the conditioned reinforcer.

    Science.gov (United States)

    Stagner, Jessica P; Laude, Jennifer R; Zentall, Thomas R

    2012-10-01

    When pigeons are given a choice between two alternatives, one leading to a stimulus 20% of the time that always signals reinforcement (S+) or another stimulus 80% of the time that signals the absence of reinforcement (S-) and the other alternative leading to one of two stimuli each signaling reinforcement 50% of the time, the 20% reinforcement alternative is preferred although it provides only 40% as much reinforcement. In Phase 1 of the present experiment, we tested the hypothesis that pigeons compare the S+ associated with each alternative and ignore the S- by giving them a choice between two pairs of discriminative stimuli (20% S+, 80% S- and 50% S+, 50% S-). Reinforcement theory suggests that the alternative associated with more reinforcement should be preferred but the pigeons showed indifference. In Phase 2, the pigeons were divided into two groups. For one group, the discriminative function was removed from the 50% reinforcement alternative and a strong preference for the 20% reinforcement alternative was found. For the other group, the discriminative function was removed from both alternatives and a strong preference was found for the 50% reinforcement alternative. Thus, the indifference found in Phase 1 was not due to the absence of discriminability of the differential reinforcement associated with the two alternatives (20% vs. 50% reinforcement); rather, the indifference can be attributed to the pigeons' insensitivity to the differential frequency of the two S+ and two S- stimuli. The relevance to human gambling behavior is discussed.

  18. Analysis and discretization of the volume penalized Laplace operator with Neumann boundary conditions

    CERN Document Server

    Kolomenskiy, Dmitry; Schneider, Kai

    2014-01-01

    We study the properties of an approximation of the Laplace operator with Neumann boundary conditions using volume penalization. For the one-dimensional Poisson equation we compute explicitly the exact solution of the penalized equation and quantify the penalization error. Numerical simulations using finite differences allow then to assess the discretisation and penalization errors. The eigenvalue problem of the penalized Laplace operator with Neumann boundary conditions is also studied. As examples in two space dimensions, we consider a Poisson equation with Neumann boundary conditions in rectangular and circular domains.

  19. FINITE VOLUME NUMERICAL ANALYSIS FOR PARABOLIC EQUATION WITH ROBIN BOUNDARY CONDITION

    Institute of Scientific and Technical Information of China (English)

    Xia Cui

    2005-01-01

    In this paper, finite volume method on unstructured meshes is studied for a parabolic convection-diffusion problem on an open bounded set of Rd (d = 2 or 3) with Robin boundary condition. Upwinding approximations are adapted to treat both the convection term and Robin boundary condition. By directly getting start from the formulation of the finite volume scheme, numerical analysis is done. By using several discrete functional analysis techniques such as summation by parts, discrete norm inequality, et al, the stability and error estimates on the approximate solution are established, existence and uniqueness of the approximate solution and the 1st order temporal norm and L2 and H1 spacial norm convergence properties are obtained.

  20. A Comparative Study of Pituitary Volume Variations in MRI in Acute Onset of Psychiatric Conditions.

    Science.gov (United States)

    Soni, Brijesh Kumar; Joish, Upendra Kumar; Sahni, Hirdesh; George, Raju A; Sivasankar, Rajeev; Aggarwal, Rohit

    2017-02-01

    The growing belief that endocrine abnormalities may underlie many mental conditions has led to increased use of imaging and hormonal assays in patients attending to psychiatric OPDs. People who are in an acute phase of a psychiatric disorder show Hypothalamic Pituitary Adrenal (HPA) axis hyperactivity, but the precise underlying central mechanisms are unclear. To assess the pituitary gland volume variations in patients presenting with new onset acute psychiatric illness in comparison with age and gender matched controls by using MRI. The study included 50 patients, with symptoms of acute psychiatric illness presenting within one month of onset of illness and 50 age and gender matched healthy controls. Both patients and controls were made to undergo MRI of the Brain. A 0.9 mm slices of entire brain were obtained by 3 dimensional T1 weighted sequence. Pituitary gland was traced in all sagittal slices. Anterior pituitary and posterior pituitary bright spot were measured separately in each slice. Volume of the pituitary (in cubic centimetre- cm(3)) was calculated by summing areas. Significance of variations in pituitary gland volumes was compared between the cases and controls using Analysis of Covariance (ANOVA). There were significantly larger pituitary gland volumes in the cases than the controls, irrespective of psychiatric diagnosis (ANOVA, f=15.56; p=0.0002). Pituitary volumes in cases were 15.36% (0.73 cm(3)) higher than in controls. There is a strong likelihood of HPA axis overactivity during initial phase of all mental disorders along with increased pituitary gland volumes. Further studies including hormonal assays and correlation with imaging are likely to provide further insight into neuroanatomical and pathological basis of psychiatric disorders.

  1. Experimental analysis of fuzzy controlled energy efficient demand controlled ventilation economizer cycle variable air volume air conditioning system

    Directory of Open Access Journals (Sweden)

    Rajagopalan Parameshwaran

    2008-01-01

    Full Text Available In the quest for energy conservative building design, there is now a great opportunity for a flexible and sophisticated air conditioning system capable of addressing better thermal comfort, indoor air quality, and energy efficiency, that are strongly desired. The variable refrigerant volume air conditioning system provides considerable energy savings, cost effectiveness and reduced space requirements. Applications of intelligent control like fuzzy logic controller, especially adapted to variable air volume air conditioning systems, have drawn more interest in recent years than classical control systems. An experimental analysis was performed to investigate the inherent operational characteristics of the combined variable refrigerant volume and variable air volume air conditioning systems under fixed ventilation, demand controlled ventilation, and combined demand controlled ventilation and economizer cycle techniques for two seasonal conditions. The test results of the variable refrigerant volume and variable air volume air conditioning system for each techniques are presented. The test results infer that the system controlled by fuzzy logic methodology and operated under the CO2 based mechanical ventilation scheme, effectively yields 37% and 56% per day of average energy-saving in summer and winter conditions, respectively. Based on the experimental results, the fuzzy based combined system can be considered to be an alternative energy efficient air conditioning scheme, having significant energy-saving potential compared to the conventional constant air volume air conditioning system.

  2. Conditional QTL Mapping of Sedimentation Volume on Seven Quality Traits in Common Wheat

    Institute of Scientific and Technical Information of China (English)

    DENG Zhi-ying; ZHAO Liang; LIU Bin; ZHANG Kun-pu; CHEN Jian-sheng; QU Hou-lan; SUN Cai-ling; ZHANG Yong-xiang; TIAN Ji-chun

    2013-01-01

    To evaluate the possible genetic interrelationships between lfour components and the sedimentation volume (SD), a doubled haploid (DH) population comprising 168 lines were used to identify the conditional quantitative trait loci (QTLs) for SD in three environments. Ten additive QTLs and 15 pairs of epistatic QTLs were detected for SD through unconditional and conditional QTL mapping. Three major additive QTLs were detected for SD conditioned on the seven quality traits. Two additive QTLs were found to be independent of these traits. Three additive QTLs were suppressed by three of the seven traits because of non-detection in unconditional mapping.Three pairs of epistatic QTLs were completely affected by the seven traits because of detection in unconditional mapping but no-detection in conditional mapping. Twelve pairs of epistatic QTLs were detected in conditional mapping. Our results indicated that conditional mapping could contribute to a better understanding of the interdependence of different and closely correlated traits at the QTL molecular level, especially some minor QTLs were found. The conditional mapping approach provides new insights that will make it possible to avoid the disadvantages of different traits by breeding through molecular design.

  3. Physical aging and structural recovery in a colloidal glass subjected to volume-fraction jump conditions

    Science.gov (United States)

    Peng, Xiaoguang; McKenna, Gregory B.

    2016-04-01

    Three important kinetic phenomena have been cataloged by Kovacs in the investigation of molecular glasses during structural recovery or physical aging. These are responses to temperature-jump histories referred to as intrinsic isotherms, asymmetry of approach, and memory effect. Here we use a thermosensitive polystyrene-poly (N -isopropylacrylamide)-poly (acrylic acid) core-shell particle-based dispersion as a colloidal model and by working at a constant number concentration of particles we use temperature changes to create volume-fraction changes. This imposes conditions similar to those defined by Kovacs on the colloidal system. We use creep experiments to probe the physical aging and structural recovery behavior of colloidal glasses in the Kovacs-type histories and compare the results with those seen in molecular glasses. We find that there are similarities in aging dynamics between molecular glasses and colloidal glasses, but differences also persist. For the intrinsic isotherms, the times teq needed for relaxing or evolving into the equilibrium (or stationary) state are relatively insensitive to the volume fraction and the values of teq are longer than the α -relaxation time τα at the same volume fraction. On the other hand, both of these times grow at least exponentially with decreasing temperature in molecular glasses. For the asymmetry of approach, similar nonlinear behavior is observed for both colloidal and molecular glasses. However, the equilibration time teq is the same for both volume-fraction up-jump and down-jump experiments, different from the finding in molecular glasses that it takes longer for the structure to evolve into equilibrium for the temperature up-jump condition than for the temperature down-jump condition. For the two-step volume-fraction jumps, a memory response is observed that is different from observations of structural recovery in two-step temperature histories in molecular glasses. The concentration dependence of the dynamics

  4. Boundary conditions for convergent radial tracer tests and effect of well bore mixing volume

    Science.gov (United States)

    Zlotnik, Vitaly A.; David Logan, J.

    Convergent radial flow tracer tests have a complex spatial nonaxial transport structure caused by the flow in the vicinity of the injection well and its finite mixing volume. The formulation of the boundary value problem, and especially the treatment of the boundary conditions at the injection well, is nontrivial. Hodgkinson and Lever [1983], Moench [1989, 1991], and Welty and Gelhar [1994] have developed different models and methods for the analysis of breakthrough curves in the extraction well. To extend interpretation techniques to breakthrough curves in the zone between injection and extraction wells, an analysis of conventional transport models is given, and improved boundary conditions are formulated for a convergent radial tracer test problem. The formulation of the boundary conditions is based upon a more detailed analysis of the kinematic flow structure and tracer mass balance in the neighborhood of the injection well. Two practical applications of revised boundary conditions for field data analysis are given. First, the note explains anomalous high well bore mixing volumes of injection wells found by Cady et al. [1993] and allows one to establish the role of mixing versus other processes (retardation, matrix diffusion, etc.). Second, it is shown that the improper use of Moench's [1989] model can produce bias in the characteristics of breakthrough curves in the extraction well under conditions that involve a significant mixing factor in the injection well. A numerical example indicates an error in peak concentrations on a breakthrough curve by as much as 70% and in peak arrival time by 10% for Peclet numbers Pe=102. The effect becomes slightly less significant for Pe=1.

  5. Feedback linearization based control of a variable air volume air conditioning system for cooling applications.

    Science.gov (United States)

    Thosar, Archana; Patra, Amit; Bhattacharyya, Souvik

    2008-07-01

    Design of a nonlinear control system for a Variable Air Volume Air Conditioning (VAVAC) plant through feedback linearization is presented in this article. VAVAC systems attempt to reduce building energy consumption while maintaining the primary role of air conditioning. The temperature of the space is maintained at a constant level by establishing a balance between the cooling load generated in the space and the air supply delivered to meet the load. The dynamic model of a VAVAC plant is derived and formulated as a MIMO bilinear system. Feedback linearization is applied for decoupling and linearization of the nonlinear model. Simulation results for a laboratory scale plant are presented to demonstrate the potential of keeping comfort and maintaining energy optimal performance by this methodology. Results obtained with a conventional PI controller and a feedback linearizing controller are compared and the superiority of the proposed approach is clearly established.

  6. Charged hadrons in local finite-volume QED+QCD with C* boundary conditions

    CERN Document Server

    Lucini, Biagio; Ramos, Alberto; Tantalo, Nazario

    2016-01-01

    In order to calculate QED corrections to hadronic physical quantities by means of lattice simulations, a coherent description of electrically-charged states in finite volume is needed. In the usual periodic setup, Gauss's law and large gauge transformations forbid the propagation of electrically-charged states. A possible solution to this problem, which does not violate the axioms of local quantum field theory, has been proposed by Wiese and Polley, and is based on the use of C* boundary conditions. We present a thorough analysis of the properties and symmetries of QED in isolation and QED coupled to QCD, with C* boundary conditions. In particular we learn that a certain class of electrically-charged states can be constructed in this setup in a fully consistent fashion, without relying on gauge fixing. We argue that this class of states covers most of the interesting phenomenological applications in the framework of numerical simulations. We also calculate finite-volume corrections to the mass of stable charg...

  7. Path Integral for Stochastic Inflation: Non-Perturbative Volume Weighting, Complex Histories, Initial Conditions and the End of Inflation

    CERN Document Server

    Gratton, Steven

    2010-01-01

    In this paper we present a path integral formulation of stochastic inflation, in which volume weighting can easily be implemented. With an in-depth study of inflation in a quartic potential, we investigate how the inflaton evolves and how inflation typically ends both with and without volume weighting. Perhaps unexpectedly, complex histories sometimes emerge with volume weighting. The reward for this excursion into the complex plane is an insight into how volume-weighted inflation both loses memory of initial conditions and ends via slow-roll. The slow-roll end of inflation mitigates certain "Youngness Paradox"-type criticisms of the volume-weighted paradigm. Thus it is perhaps time to rehabilitate proper time volume weighting as a viable measure for answering at least some interesting cosmological questions.

  8. Effects of swim training on lung volumes and inspiratory muscle conditioning.

    Science.gov (United States)

    Clanton, T L; Dixon, G F; Drake, J; Gadek, J E

    1987-01-01

    Lung volumes and inspiratory muscle (IM) function tests were measured in 16 competitive female swimmers (age 19 +/- 1 yr) before and after 12 wk of swim training. Eight underwent additional IM training; the remaining eight were controls. Vital capacity (VC) increased 0.25 +/- 0.25 liters (P less than 0.01), functional residual capacity (FRC) increased 0.39 +/- 0.29 liters (P less than 0.001), and total lung capacity (TLC) increased 0.35 +/- 0.47 (P less than 0.025) in swimmers, irrespective of IM training. Residual volume (RV) did not change. Maximum inspiratory mouth pressure (PImax) measured at FRC changed -43 +/- 18 cmH2O (P less than 0.005) in swimmers undergoing IM conditioning and -29 +/- 25 (P less than 0.05) in controls. The time that 65% of prestudy PImax could be endured increased in IM trainers (P less than 0.001) and controls (P less than 0.05). All results were compared with similar IM training in normal females (age 21.1 +/- 0.8 yr) in which significant increases in PImax and endurance were observed in IM trainers only with no changes in VC, FRC, or TLC (Clanton et al., Chest 87: 62-66, 1985). We conclude that 1) swim training in mature females increases VC, TLC, and FRC with no effect on RV, and 2) swim training increases IM strength and endurance measured near FRC.

  9. Investigations on the emissions of biocides and PCBs under low volume conditions.

    Science.gov (United States)

    Mull, Birte; Horn, Wolfgang; Jann, Oliver

    2015-01-01

    The aim of this study was the development of a low volume air sampling strategy for biocides and polychlorinated biphenyls (PCB) at low air change rates in modern, air-tight showcases as they are present in museums. Lindane, pentachlorophenol, dichlofluanid, tolyfluanid, isodrin, p,p-dichlorodiphenyl trichloroethane and permethrin were the biocides and PCB28 and PCB153 were the PCBs studied, all of which are semi volatile organic compounds (SVOC). Their occurrences in the museum environment originate from various sources e.g. preventive treatment of organic exhibits or organic building materials. Exhibits are long-term exposed to these pollutants due to storing in showcases or other storage equipment at low air change rates. To achieve air sampling under the aforementioned conditions the influences of temperature, air circulation, air change rate and relative humidity on the emission behavior of the selected biocides and PCBs had to be determined. This was carried out with pre-soaked wood samples in low volume air sampling experiments using 27L test showcases and 23L and 24L emission test chambers and also diffusive sampling with glass as the sampling material.

  10. Efeitos das respostas de observação diferenciais sobre a aprendizagem de relações condicionais com estímulos complexos Effects of differential observing responses on the learning of conditional relations with complex stimuli

    Directory of Open Access Journals (Sweden)

    Jair Lopes Junior

    2003-01-01

    Full Text Available Este estudo avaliou se relações entre os componentes do estímulo modelo complexo exerceriam controle condicional em tarefas de matching-to-sample simultâneo. Na Fase 1, 3 crianças com necessidades especiais de ensino foram expostas ao treino das relações A1B1 e A2B2 e ao teste das respectivas relações simétricas. Em seguida, as contingências de treino exigiram respostas de observação diferenciais que consistiram no estabelecimento de relações condicionais de identidade entre estímulos complexos (relações AB-AB precedendo o acesso ao treino das relações condicionais ABX. Neste treino, diante de estímulos modelos complexos cujos componentes sustentavam condicionalidade treinada (A1B1 e A2B2, X1 foi o estímulo de escolha correto; X2 exerceu esta função quando os componentes do estímulo modelo não sustentavam tal relação (A1B2 e A2B1. Na Fase 2, ocorreria o treino PQ, testes QP e PQX que avaliariam a extensão do controle condicional definido pelas relações entre os estímulos P e Q. As três crianças registraram a aprendizagem das relações AB, a emergência das relações simétricas e índices elevados de acerto nas respostas de observação diferenciais, ou seja, no estabelecimento das relações condicionais de identidade com estímulos complexos. Contudo, as três demonstraram relações de controle distintas das previstas no treino ABX, sendo, portanto, o experimento finalizado na Fase 1. Tais resultados sugerem uma independência funcional entre as habilidades discriminativas exigidas nas duas contingências de ensino de relações condicionais com estímulos modelo complexos.This study evaluated if relations between components of complex sample stimuli would have controlled conditional responding in identity and arbitrary simultaneous matching-to-sample tasks. In Phase 1, 3 children with educational special needs were trained to select stimulus B1 in the presence of stimulus A1, and select B2 in the presence

  11. Spray ignition measurements in a constant volume combustion vessel under engine-relevant conditions

    Science.gov (United States)

    Ramesh, Varun

    Pressure-based and optical diagnostics for ignition delay (ID) measurement of a diesel spray from a multi-hole nozzle were investigated in a constant volume combustion vessel (CVCV) at conditions similar to those in a conventional diesel engine at the start of injection (SOI). It was first hypothesized that compared to an engine, the shorter ID in a CVCV was caused by NO, a byproduct of premixed combustion. The presence of a significant concentration of NO+NO2 was confirmed experimentally and by using a multi-zone model of premixed combustion. Experiments measuring the effect of NO on ID were performed at conditions relevant to a conventional diesel engine. Depending on the temperature regime and the nature of the fuel, NO addition was found to advance or retard ignition. Constant volume ignition simulations were capable of describing the observed trends; the magnitudes were different due to the physical processes involved in spray ignition, not modeled in the current study. The results of the study showed that ID is sensitive to low NO concentrations (<100 PPM) in the low-temperature regime. A second source of uncertainty in pressure-based ID measurement is the systematic error associated with the correction used to account for the speed of sound. Simultaneous measurements of volumetric OH chemiluminescence (OHC) and pressure during spray ignition found the OHC to closely resemble the pressure-based heat release rate for the full combustion duration. The start of OHC was always found to be shorter than the pressure-based ID for all fuels and conditions tested by 100 ms. Experiments were also conducted measuring the location and timing of high-temperature ignition and the steady-state lift-off length by high-speed imaging of OHC during spray ignition. The delay period calculated using the measured ignition location and the bulk average speed of sound was in agreement with the delay between OHC and the pressure-based ID. Results of the study show that start of OHC

  12. Final Report - Advanced MEA's for Enhanced Operating Conditions, Amenable to High Volume Manufacture

    Energy Technology Data Exchange (ETDEWEB)

    Debe, Mark K.

    2007-09-30

    This report summarizes the work completed under a 3M/DOE contract directed at advancing the key fuel cell (FC) components most critical for overcoming the polymer electrolyte membrane fuel cell (PEMFC) performance, durability & cost barriers. This contract focused on the development of advanced ion exchange membranes & electrocatalysts for PEMFCs that will enable operation under ever more demanding automotive operating conditions & the use high volume compatible processes for their manufacture. Higher performing & more durable electrocatalysts must be developed for PEMFCs to meet the power density & lifetime hours required for FC vehicles. At the same time the amount of expensive Pt catalyst must be reduced to lower the MEA costs. While these two properties are met, the catalyst must be made resistant to multiple degradation mechanisms to reach necessary operating lifetimes. In this report, we present the work focused on the development of a completely new approach to PEMFC electrocatalyts, called nanostructured thin film (NSTF) catalysts. The carbon black supports are eliminated with this new approach which eliminates the carbon corrosion issue. The thin film nature of the catalyst significantly improves its robustness against dissolution & grain growth, preserving the surface area. Also, the activity of the NSTF for oxygen reduction is improved by over 500% compared to dispersed Pt catalyts. Finally, the process for fabricating the NSTF catalysts is consistent with high volume roll-good manufacturing & extremely flexible towards the introduction of new catalyst compositions & structures. This report documents the work done to develop new multi-element NSTF catalysts with properties that exceed pure Pt, that are optimized for use with the membranes discussed below, & advance the state-of-the-art towards meeting the DOE 2010 targets for PEMFC electrocatalysts. The work completed advances the understanding of the NSTF catalyst technology, identifies new NSTF

  13. Final Report - Advanced MEA's for Enhanced Operating Conditions, Amenable to High Volume Manufacture

    Energy Technology Data Exchange (ETDEWEB)

    Debe, Mark K.

    2007-09-30

    This report summarizes the work completed under a 3M/DOE contract directed at advancing the key fuel cell (FC) components most critical for overcoming the polymer electrolyte membrane fuel cell (PEMFC) performance, durability & cost barriers. This contract focused on the development of advanced ion exchange membranes & electrocatalysts for PEMFCs that will enable operation under ever more demanding automotive operating conditions & the use high volume compatible processes for their manufacture. Higher performing & more durable electrocatalysts must be developed for PEMFCs to meet the power density & lifetime hours required for FC vehicles. At the same time the amount of expensive Pt catalyst must be reduced to lower the MEA costs. While these two properties are met, the catalyst must be made resistant to multiple degradation mechanisms to reach necessary operating lifetimes. In this report, we present the work focused on the development of a completely new approach to PEMFC electrocatalyts, called nanostructured thin film (NSTF) catalysts. The carbon black supports are eliminated with this new approach which eliminates the carbon corrosion issue. The thin film nature of the catalyst significantly improves its robustness against dissolution & grain growth, preserving the surface area. Also, the activity of the NSTF for oxygen reduction is improved by over 500% compared to dispersed Pt catalyts. Finally, the process for fabricating the NSTF catalysts is consistent with high volume roll-good manufacturing & extremely flexible towards the introduction of new catalyst compositions & structures. This report documents the work done to develop new multi-element NSTF catalysts with properties that exceed pure Pt, that are optimized for use with the membranes discussed below, & advance the state-of-the-art towards meeting the DOE 2010 targets for PEMFC electrocatalysts. The work completed advances the understanding of the NSTF catalyst technology, identifies new NSTF

  14. Hybrid Multiscale Finite Volume Method for Advection-Diffusion Equations Subject to Heterogeneous Reactive Boundary Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Barajas-Solano, David A.; Tartakovsky, A. M.

    2016-10-13

    We present a hybrid scheme for the coupling of macro and microscale continuum models for reactive contaminant transport in fractured and porous media. The transport model considered is the advection-dispersion equation, subject to linear heterogeneous reactive boundary conditions. The Multiscale Finite Volume method (MsFV) is employed to define an approximation to the microscale concentration field defined in terms of macroscopic or \\emph{global} degrees of freedom, together with local interpolator and corrector functions capturing microscopic spatial variability. The macroscopic mass balance relations for the MsFV global degrees of freedom are coupled with the macroscopic model, resulting in a global problem for the simultaneous time-stepping of all macroscopic degrees of freedom throughout the domain. In order to perform the hybrid coupling, the micro and macroscale models are applied over overlapping subdomains of the simulation domain, with the overlap denoted as the handshake subdomain $\\Omega^{hs}$, over which continuity of concentration and transport fluxes between models is enforced. Continuity of concentration is enforced by posing a restriction relation between models over $\\Omega^{hs}$. Continuity of fluxes is enforced by prolongating the macroscopic model fluxes across the boundary of $\\Omega^{hs}$ to microscopic resolution. The microscopic interpolator and corrector functions are solutions to local microscopic advection-diffusion problems decoupled from the global degrees of freedom and from each other by virtue of the MsFV decoupling ansatz. The error introduced by the decoupling ansatz is reduced iteratively by the preconditioned GMRES algorithm, with the hybrid MsFV operator serving as the preconditioner.

  15. Efficient Procedure to Compute the Microcanonical Volume of Initial Conditions that Lead to Escape Trajectories from a Multidimensional Potential Well

    NARCIS (Netherlands)

    Waalkens, Holger; Burbanks, Andrew; Wiggins, Stephen

    2005-01-01

    A procedure is presented for computing the phase space volume of initial conditions for trajectories that escape or ‘‘react’’ from a multidimensional potential well. The procedure combines a phase space transition state theory, which allows one to construct dividing surfaces that are free of local r

  16. Individual perception of different stimuli: Implications for managers

    Directory of Open Access Journals (Sweden)

    Santos- Álvarez, M.V.

    2012-01-01

    Full Text Available Managerial perception is the process by which managers form an image of the stimuli they receive. According to research, perception is conditioned by the individual’s cognitive profile. But the different nature of incoming stimuli suggests that it would be interesting to study whether the cognitive profile’s influence varies in the presence of different stimuli. This paper analyses the effect of the cognitive profile on perception of differently-structured stimuli. The results clearly show that the cognitive style, tolerance of ambiguity, and proactivity have an effect. Specifically, they condition the recognition of stimuli, particularly when the stimuli are relatively unstructured. The results also show that the cognitive variables have less influence in the interpretation stage.

  17. Miniaturized, High Flow, Low Dead Volume Preconcentrator for Trace Contaminants in Water under Microgravity Conditions Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Thorleaf Research, Inc. has demonstrated feasibility in Phase I and now proposes a Phase II effort to develop a miniaturized high flow, low dead-volume...

  18. Volume regulation in rat pheochromocytoma cultured cells submitted to hypoosmotic conditions.

    Science.gov (United States)

    Delpire, E; Cornet, M; Gilles, R

    1991-02-01

    The mechanisms at work in cell volume regulation have been studied in PC12 cultured cells. Results show, for the first time to our knowledge, that the volume readjustment process occurring after application of a hypoosmotic saline is sensitive to amiloride, IBMX and forskoline. The process is also inhibited by quinine hydrochloride and trifluoperazine. Volume readjustment is concomtant with a decrease in K+ and Cl- intracellular levels. The decrease in K+ level can be related to an assymetrical change in the fluxes in and out of the ion as shown by flux kinetics studies using Rb86. These results are interpreted considering that the control of the activity of the ion channel pathways associated with volume readjustment in PC12 cells may implicate the Ca(2+)-calmodulin - cAMP system.

  19. Effects of mechanical stimuli on adaptive remodeling of condylar cartilage.

    Science.gov (United States)

    Sriram, D; Jones, A; Alatli-Burt, I; Darendeliler, M A

    2009-05-01

    Trabecular bone has been shown to be responsive to low-magnitude, high-frequency mechanical stimuli. This study aimed to assess the effects of these stimuli on condylar cartilage and its endochondral bone. Forty female 12-week-old C3H mice were divided into 3 groups: baseline control (killed at day 0), sham (killed at day 28 without exposure to mechanical stimuli), and experimental (killed following 28 days of exposure to mechanical stimuli). The experimental group was subjected to mechanical vibration of 30 Hz, for 20 minutes per day, 5 days per week, for 28 days. The specimens were analyzed by micro-computed tomography. The experimental group demonstrated a significant decrease in the volume of condylar cartilage and also a significant increase in bone histomorphometric parameters. The results suggest that the low-magnitude, high-frequency mechanical stimuli enhance adaptive remodeling of condylar cartilage, evidenced by the advent of endochondral bone replacing the hypertrophic cartilage.

  20. Stimuli-Regulated Smart Polymeric Systems for Gene Therapy

    Directory of Open Access Journals (Sweden)

    Ansuja Pulickal Mathew

    2017-04-01

    Full Text Available The physiological condition of the human body is a composite of different environments, each with its own parameters that may differ under normal, as well as diseased conditions. These environmental conditions include factors, such as pH, temperature and enzymes that are specific to a type of cell, tissue or organ or a pathological state, such as inflammation, cancer or infection. These conditions can act as specific triggers or stimuli for the efficient release of therapeutics at their destination by overcoming many physiological and biological barriers. The efficacy of conventional treatment modalities can be enhanced, side effects decreased and patient compliance improved by using stimuli-responsive material that respond to these triggers at the target site. These stimuli or triggers can be physical, chemical or biological and can be internal or external in nature. Many smart/intelligent stimuli-responsive therapeutic gene carriers have been developed that can respond to either internal stimuli, which may be normally present, overexpressed or present in decreased levels, owing to a disease, or to stimuli that are applied externally, such as magnetic fields. This review focuses on the effects of various internal stimuli, such as temperature, pH, redox potential, enzymes, osmotic activity and other biomolecules that are present in the body, on modulating gene expression by using stimuli-regulated smart polymeric carriers.

  1. Trophic interactions among sympatric zooplanktivorous fish species in volume change conditions in a large, shallow, tropical lake

    Directory of Open Access Journals (Sweden)

    Rodrigo Moncayo-Estrada

    Full Text Available Significant reductions in the water volume of shallow lakes impose a restriction on species segregation promoting more interactions in the trophic relationships. The diets of three closely related zooplanktivorous silversides belonging to the Atherinopsidae species flock of lake Chapala , Mexico, were analyzed at two sites (Chirostoma jordani, C. labarcae, and C. consocium. Diets were described in critical shallow (August 2000 and volume recovery conditions (August 2005. Diets included mainly cladocerans (Bosmina, Ceriodaphnia, and Daphnia and copepods (Cyclops. A significant difference in diets was detected when comparing years (MRPP analysis, A = 0.22, p < 0.0001 and sites at different years (MRPP analysis, A = 0.17, p = 0.004. According to niche breadth mean values, species were classified as specialized and intermediate feeders. In shallow conditions, the small range of niche breadth (1.72 to 3.64 and high diet overlap values (D = 0.64, L = 8.62 indicated a high potential for interspecific exploitative interaction. When the lake volume recovered, an increase in the niche breadth range (1.04 to 4.96 and low niche overlap values (D = 0.53, L = 2.32 indicated a reduction of the species interaction. The Mann-Whitney U-test supported this pattern by showing a significant difference between years for niche overlap (p = 0.006. The increased interaction during the low volume suggests alternative segregation in life-history variations and other niche dimensions such as spatial or temporal distribution.

  2. Seeing and feeling volumes: The influence of shape on volume perception.

    Science.gov (United States)

    Kahrimanovic, Mirela; Bergmann Tiest, Wouter M; Kappers, Astrid M L

    2010-07-01

    The volume of common objects can be perceived visually, haptically or by a combination of both senses. The present study shows large effects of the object's shape on volume perception within all these modalities, with an average bias of 36%. In all conditions, the volume of a tetrahedron was overestimated compared to that of a cube or a sphere, and the volume of a cube was overestimated compared to that of a sphere. Additional analyses revealed that the biases could be explained by the dependence of the volume judgment on different geometric properties. During visual volume perception, the strategies depended on the objects that were compared and they were also subject-dependent. However, analysis of the haptic and bimodal data showed more consistent results and revealed that surface area of the stimuli influenced haptic as well as bimodal volume perception. This suggests that bimodal volume perception is more influenced by haptic input than by visual information.

  3. Thermo-Responsive Hydrogels for Stimuli-Responsive Membranes

    Directory of Open Access Journals (Sweden)

    Evan Mah

    2013-09-01

    Full Text Available Composite membranes with stimuli-responsive properties can be made by coating a thermo-responsive hydrogel onto a micro- or macroporous support. These hydrogels undergo a temperature induced volume-phase transition, which contributes towards the composite membrane’s stimuli-responsive properties. This paper reviews research done on complimentary forms of temperature responsive “thermophilic” hydrogels, those exhibiting positive volume-phase transitions in aqueous solvent. The influences of intermolecular forces on the mechanism of phase-transition are discussed along with case examples of typical thermophilic hydrogels.

  4. Patient Selection and Volume in the Era Surrounding Implementation of Medicare Conditions of Participation for Transplant Programs

    Science.gov (United States)

    White, Sarah L; Zinsser, Dawn M; Paul, Matthew; Levine, Gregory N; Shearon, Tempie; Ashby, Valarie B; Magee, John C; Li, Yi; Leichtman, Alan B

    2015-01-01

    Objective To evaluate evidence of practice changes affecting kidney transplant program volumes, and donor, recipient and candidate selection in the era surrounding the introduction of Centers for Medicare and Medicaid Services (CMS) conditions of participation (CoPs) for organ transplant programs. Data Scientific Registry of Transplant Recipients; CMS ESRD and Medicare claims databases. Design Retrospective analysis of national registry data. Methods A Cox proportional hazards model of 1-year graft survival was used to derive risks associated with deceased-donor kidney transplants performed from 2001 to 2010. Findings Among programs with ongoing noncompliance with the CoPs, kidney transplant volumes declined by 38 percent (n = 766) from 2006 to 2011, including a 55 percent drop in expanded criteria donor transplants. Volume increased by 6 percent (n = 638) among programs remaining in compliance. Aggregate risk of 1-year graft failure increased over time due to increasing recipient age and obesity, and longer ESRD duration. Conclusions Although trends in aggregate risk of 1-year kidney graft loss do not indicate that the introduction of the CoPs has systematically reduced opportunities for marginal candidates or that there has been a systematic shift away from utilization of higher risk deceased donor kidneys, total volume and expanded criteria donor utilization decreased overall among programs with ongoing noncompliance. PMID:24838079

  5. Contingent stimuli signal subsequent reinforcer ratios.

    Science.gov (United States)

    Boutros, Nathalie; Davison, Michael; Elliffe, Douglas

    2011-07-01

    Conditioned reinforcer effects may be due to the stimulus' discriminative rather than its strengthening properties. While this was demonstrated in a frequently-changing choice procedure, a single attempt to replicate in a relatively static choice environment failed. We contend that this was because the information provided by the stimuli was nonredundant in the frequently-changing preparation, and redundant in the steady-state arrangement. In the present experiments, 6 pigeons worked in a steady-state concurrent schedule procedure with nonredundant informative stimuli (red keylight illuminations). When a response-contingent red keylight signaled that the next food delivery was more likely on one of the two alternatives, postkeylight choice responding was reliably for that alternative. This effect was enhanced after a history of extended informative red keylight presentation (Experiment 2). These results lend support to recent characterizations of conditioned reinforcer effects as reflective of a discriminative, rather than a reinforcing, property of the stimulus.

  6. A surface acoustic wave-driven micropump for particle uptake investigation under physiological flow conditions in very small volumes

    Directory of Open Access Journals (Sweden)

    Florian G. Strobl

    2015-02-01

    Full Text Available Static conditions represent an important shortcoming of many in vitro experiments on the cellular uptake of nanoparticles. Here, we present a versatile microfluidic device based on acoustic streaming induced by surface acoustic waves (SAWs. The device offers a convenient method for introducing fluid motion in standard cell culture chambers and for mimicking capillary blood flow. We show that shear rates over the whole physiological range in sample volumes as small as 200 μL can be achieved. A precise characterization method for the induced flow profile is presented and the influence of flow on the uptake of Pt-decorated CeO2 particles by endothelial cells (HMEC-1 is demonstrated. Under physiological flow conditions the particle uptake rates for this system are significantly lower than at low shear conditions. This underlines the vital importance of the fluidic environment for cellular uptake mechanisms.

  7. Approximation of the Laplace and Stokes operators with Dirichlet boundary conditions through volume penalization: a spectral viewpoint

    CERN Document Server

    van yen, Romain Nguyen; Schneider, Kai

    2012-01-01

    We report the results of a detailed study of the spectral properties of Laplace and Stokes operators, modified with a volume penalization term designed to approximate Dirichlet conditions in the limit when a penalization parameter, $\\eta$, tends to zero. The eigenvalues and eigenfunctions are determined either analytically or numerically as functions of $\\eta$, both in the continuous case and after applying Fourier or finite difference discretization schemes. For fixed $\\eta$, we find that only the part of the spectrum corresponding to eigenvalues $\\lambda \\lesssim \\eta^{-1}$ approaches Dirichlet boundary conditions, while the remainder of the spectrum is made of uncontrolled, spurious wall modes. The penalization error for the controlled eigenfunctions is estimated as a function of $\\eta$ and $\\lambda$. Surprisingly, in the Stokes case, we show that the eigenfunctions approximately satisfy, with a precision $O(\\eta)$, Navier slip boundary conditions with slip length equal to $\\sqrt{\\eta}$. Moreover, for a gi...

  8. Protein-surface interactions on stimuli-responsive polymeric biomaterials.

    Science.gov (United States)

    Cross, Michael C; Toomey, Ryan G; Gallant, Nathan D

    2016-03-04

    Responsive surfaces: a review of the dependence of protein adsorption on the reversible volume phase transition in stimuli-responsive polymers. Specifically addressed are a widely studied subset: thermoresponsive polymers. Findings are also generalizable to other materials which undergo a similarly reversible volume phase transition. As of 2015, over 100,000 articles have been published on stimuli-responsive polymers and many more on protein-biomaterial interactions. Significantly, fewer than 100 of these have focused specifically on protein interactions with stimuli-responsive polymers. These report a clear trend of increased protein adsorption in the collapsed state compared to the swollen state. This control over protein interactions makes stimuli-responsive polymers highly useful in biomedical applications such as wound repair scaffolds, on-demand drug delivery, and antifouling surfaces. Outstanding questions are whether the protein adsorption is reversible with the volume phase transition and whether there is a time-dependence. A clear understanding of protein interactions with stimuli-responsive polymers will advance theoretical models, experimental results, and biomedical applications.

  9. Osmosis-induced water uptake by Eurobitum bituminized radioactive waste and pressure development in constant volume conditions

    Science.gov (United States)

    Mariën, A.; Mokni, N.; Valcke, E.; Olivella, S.; Smets, S.; Li, X.

    2013-01-01

    The chemo-hydro-mechanical (CHM) interaction between swelling Eurobitum radioactive bituminized waste (BW) and Boom Clay is investigated to assess the feasibility of geological disposal for the long-term management of this waste. These so-called compatibility studies include laboratory water uptake tests at the Belgian Nuclear Research Center SCK•CEN, and the development of a coupled CHM formulation for Eurobitum by the International Center for Numerical Methods and Engineering (CIMNE, Polytechnical University of Cataluña, Spain). In the water uptake tests, the osmosis-induced swelling, pressure increase and NaNO3 leaching of small cylindrical BW samples (diameter 38 mm, height 10 mm) is studied under constant total stress conditions and nearly constant volume conditions; the actual geological disposal conditions should be intermediate between these extremes. Two nearly constant volume tests were stopped after 1036 and 1555 days to characterize the morphology of the hydrated BW samples and to visualize the hydrated part with microfocus X-ray Computer Tomography (μCT) and Environmental Scanning Electron Microscopy (ESEM). In parallel, a coupled CHM formulation is developed that describes chemically and hydraulically coupled flow processes in porous materials with salt crystals, and that incorporates a porosity dependent membrane efficiency, permeability and diffusivity. When Eurobitum BW is hydrated in (nearly) constant volume conditions, the osmosis-induced water uptake results in an increasing pressure to values that can be (in theory) as high as 42.8 MPa, being the osmotic pressure of a saturated NaNO3 solution. After about four years of hydration in nearly constant volume water uptake tests, pressures up to 20 MPa are measured. During this hydration period only the outer layers with a thickness of 1-2 mm were hydrated (as derived from μCT and ESEM analyses), and only about 10-20% of the initial NaNO3 content was released by the samples. In the studied test

  10. Emotional stimuli and motor conversion disorder

    NARCIS (Netherlands)

    Voon, V.; Brezing, C.; Gallea, C.; Ameli, R.; Roelofs, K.; LaFrance, W.C.; Hallett, M.

    2010-01-01

    Conversion disorder is characterized by neurological signs and symptoms related to an underlying psychological issue. Amygdala activity to affective stimuli is well characterized in healthy volunteers with greater amygdala activity to both negative and positive stimuli relative to neutral stimuli,

  11. Comparative analysis of operational forecasts versus actual weather conditions in airline flight planning, volume 2

    Science.gov (United States)

    Keitz, J. F.

    1982-01-01

    The impact of more timely and accurate weather data on airline flight planning with the emphasis on fuel savings is studied. This volume of the report discusses the results of Task 2 of the four major tasks included in the study. Task 2 compares various catagories of flight plans and flight tracking data produced by a simulation system developed for the Federal Aviation Administrations by SRI International. (Flight tracking data simulate actual flight tracks of all aircraft operating at a given time and provide for rerouting of flights as necessary to resolve traffic conflicts.) The comparisons of flight plans on the forecast to flight plans on the verifying analysis confirm Task 1 findings that wind speeds are generally underestimated. Comparisons involving flight tracking data indicate that actual fuel burn is always higher than planned, in either direction, and even when the same weather data set is used. Since the flight tracking model output results in more diversions than is known to be the case, it was concluded that there is an error in the flight tracking algorithm.

  12. Local-Rapid Evaluation of Atmospheric Conditions (L-REAC (trademark)) System, Volume 4 (System Evaluation)

    Science.gov (United States)

    2011-12-01

    first responder s operational decision aid called the Local-Rapid Evaluation of Atmospheric Conditions (L-REAC ) System . As part of the technology transfer process, a detailed evaluation of the L-REAC System was conducted by volunteer and professional emergency first responders. This report documents the evaluation process, results and recommendations. In short, all evaluators independently stated that they would recommend the L-REAC System for

  13. Energy storage and power conditioning aspects of photovoltaic solar power systems. Volume I. First quarterly report

    Energy Technology Data Exchange (ETDEWEB)

    1975-10-01

    Solar energy may be utilized as thermal energy or converted into electricity by solar cells. ERDA's National Photovoltaic Conversion Program is concerned with this latter approach and is currently sponsoring industrial programs for photovoltaic systems and devices. In one such program, Spectrolab, Inc., is charged with performing conceptual design and analysis of three photovoltaic solar power systems. The sizes of these three systems will cover the requirements of residential, commercial and electric utility central station applications. In addition to a solar cell array, photovoltaic power systems must also include an energy storage system to enable operation during periods of low insolation and a power conditioning system to control the dc power from the array and convert it into an ac waveshape compatible with existing electrical equipment. The Scientific Development Operation of Bechtel Corporation is participating in the Spectrolab program by compiling and studying data on the energy storage and power conditioning aspects of all three photovoltaic solar power systems and by the conceptual design of the system for electric utility central station applications. The results of the energy storage and power conditioning study effort are presented in this report. (W.D.M.)

  14. A QR accelerated volume-to-surface boundary condition for finite element solution of eddy current problems

    Energy Technology Data Exchange (ETDEWEB)

    White, D; Fasenfest, B; Rieben, R; Stowell, M

    2006-09-08

    We are concerned with the solution of time-dependent electromagnetic eddy current problems using a finite element formulation on three-dimensional unstructured meshes. We allow for multiple conducting regions, and our goal is to develop an efficient computational method that does not require a computational mesh of the air/vacuum regions. This requires a sophisticated global boundary condition specifying the total fields on the conductor boundaries. We propose a Biot-Savart law based volume-to-surface boundary condition to meet this requirement. This Biot-Savart approach is demonstrated to be very accurate. In addition, this approach can be accelerated via a low-rank QR approximation of the discretized Biot-Savart law.

  15. Permeability of coal to CH4 under fixed volume boundary conditions: the effect of stress-strain-sorption behaviour

    Science.gov (United States)

    Liu, Jinfeng; Fokker, Peter; Spiers, Christopher

    2016-04-01

    Permeability evolution in coal reservoirs during CO2-Enhanced Coalbed Methane (ECBM) production is strongly influenced by swelling/shrinkage effects related to sorption and desorption of CO2 and CH4, respectively. Numerous permeability models, coupling the swelling response of coal to gas sorption, have been developed to predict in-situ coal seam permeability evolution during (E)CBM. However, experimental studies, aimed at testing such models, have mainly focused on the permeability changes occurring under constant lateral stress conditions, which are inconsistent with the in-situ boundary condition of (near) zero lateral strain. We performed CH4 permeability measurements, using the steady-state method, on a cylindrical sample of high volatile bituminous coal (25mm in diameter), under (near) fixed volume versus fixed stress conditions. The sample possessed a clearly visible cleat system. To isolate the effect of sorption on permeability evolution, helium (non-sorbing gas) was used as a control fluid. The bulk sample permeability to helium, under stress control conditions, changed from 4.07×10-17to 7.5×10-18m2, when the effective stress increased from 19.1 to 35.2MPa. Sorption of CH4 at a constant pressure of 10MPa, under fixed volume boundary conditions, resulted in a confining pressure increase from a poroelastically supported value of 29.3MPa to a near-equilibrium value of 38.6MPa over 171 hours. This is caused by the combined effect of the sorption-induced swelling and the self-compression of the sample. The concentration of CH4 adsorbed by the sample was 0.113 mmol/gcoal. During the adsorption process, the permeability to CH4 also decreased from 2.38×10-17 to 4.91×10-18m2, proving a strong influence of stress-strain-sorption behavior (c.f. Hol et al., 2012) on fracture permeability evolution. The CH4 permeability subsequently measured under stress controlled conditions varied from 1.37×10-17 to 4.33×10-18m2, for same change in confining pressure, i.e. 28

  16. Charged hadrons in local finite-volume QED+QCD with C{sup ⋆} boundary conditions

    Energy Technology Data Exchange (ETDEWEB)

    Lucini, B. [Physics Department, College of Science, Swansea University,Singleton Park, Swansea SA2 8PP (United Kingdom); Patella, A. [PH-TH, CERN,CH-1211 Geneva 23 (Switzerland); School of Computing and Mathematics & Centre for Mathematical Science, Plymouth University,Plymouth PL4 8AA (United Kingdom); Ramos, A. [PH-TH, CERN,CH-1211 Geneva 23 (Switzerland); Tantalo, N. [Dipartimento di Fisica and INFN, Università di Roma “Tor Vergata”,Via della Ricerca Scientifica 1, I-00133 Roma (Italy); PH-TH, CERN,CH-1211 Geneva 23 (Switzerland)

    2016-02-11

    In order to calculate QED corrections to hadronic physical quantities by means of lattice simulations, a coherent description of electrically-charged states in finite volume is needed. In the usual periodic setup, Gauss’s law and large gauge transformations forbid the propagation of electrically-charged states. A possible solution to this problem, which does not violate the axioms of local quantum field theory, has been proposed by Wiese and Polley, and is based on the use of C{sup ⋆} boundary conditions. We present a thorough analysis of the properties and symmetries of QED in isolation and QED coupled to QCD, with C{sup ⋆} boundary conditions. In particular we learn that a certain class of electrically-charged states can be constructed in a fully consistent fashion without relying on gauge fixing and without peculiar complications. This class includes single particle states of most stable hadrons. We also calculate finite-volume corrections to the mass of stable charged particles and show that these are much smaller than in non-local formulations of QED.

  17. SU(N) Gauge Theories with C-Periodic Boundary Conditions II. Small Volume Dynamics

    CERN Document Server

    Kronfeld, Andreas S

    1993-01-01

    The dynamics of SU(N) gauge theories, especially for N=3, in a small C-periodic box are investigated. We identify the fields that mimimize the energy---the torons---and determine which of these ``classical'' vacua are stable quantum mechanically. The stable torons break cubic symmetry, which has interesting consequences on the spectrum. At any of the stable torons there are also quartic modes. Since all C-periodic boundary conditions are gauge-equivalent, we choose a convenient version, for which the quartic modes are constant modes, and compute the effective Hamiltonian to one loop in perturbation theory.

  18. Compatibility of refrigerants and lubricants with motor materials under retrofit conditions. Final report, Volume 1

    Energy Technology Data Exchange (ETDEWEB)

    Doerr, R.G.; Waite, T.D. [The Trane Company, La Crosse, WI (United States)

    1996-10-01

    Compatibility tests were conducted on motor materials to determine if exposure to the original refrigerant/mineral oil would affect compatibility of the motor materials after retrofit to the alternative refrigerant/lubricant. The motor materials were exposed at elevated temperature to the original refrigerant and mineral oil for 500 hours, followed by exposure to the alternative refrigerant and lubricant for 500 hours. Measurements were also taken after 168 and 336 hours. As a control, some samples were exposed to the original refrigerant/mineral oil for a total of 1000 hours. The original refrigerants and the Alternatives tested for retrofit were as follows: Most motor materials exposed to the alternative refrigerant and lubricant (after an initial exposure to the original refrigerant and mineral oil) were compatible with the alternative refrigerant and lubricant. The only concern was delamination and blistering of the sheet insulation containing Nomex, especially after removal of absorbed refrigerant. This was attributed to solution of the adhesive and not to the Nomex itself. Embrittlement of the polyethylene terephthalate (PET) found in Mylar and Melinex sheet and sleeving insulations was initially observed, but subsequent tests under dry conditions showed that embrittlement of the PET materials was caused by moisture present during the exposure. Compatibility tests of elastomers with R-245ca, retrofitted from R-11 and R-123, showed that the nitrile was compatible with both R-11 and R-245ca, but not with R-123. The neoprene was unsatisfactory because of shrinkage in the R-245ca.

  19. Animation Stimuli System for Research on Instructor Gestures in Education.

    Science.gov (United States)

    Cui, Jian; Popescu, Voicu; Adamo-Villani, Nicoletta; Wagner Cook, Susan; Duggan, Katherine A; Friedman, Howard S

    2017-01-01

    Education research has shown that instructor gestures can help capture, maintain, and direct the student's attention during a lecture as well as enhance learning and retention. Traditional education research on instructor gestures relies on video stimuli, which are time consuming to produce, especially when gesture precision and consistency across conditions are strictly enforced. The proposed system allows users to efficiently create accurate and effective stimuli for complex studies on gesture, without the need for computer animation expertise or artist talent.

  20. A comparison of least squares and conditional maximum likelihood estimators under volume endpoint censoring in tumor growth experiments.

    Science.gov (United States)

    Roy Choudhury, Kingshuk; O'Sullivan, Finbarr; Kasman, Ian; Plowman, Greg D

    2012-12-20

    Measurements in tumor growth experiments are stopped once the tumor volume exceeds a preset threshold: a mechanism we term volume endpoint censoring. We argue that this type of censoring is informative. Further, least squares (LS) parameter estimates are shown to suffer a bias in a general parametric model for tumor growth with an independent and identically distributed measurement error, both theoretically and in simulation experiments. In a linear growth model, the magnitude of bias in the LS growth rate estimate increases with the growth rate and the standard deviation of measurement error. We propose a conditional maximum likelihood estimation procedure, which is shown both theoretically and in simulation experiments to yield approximately unbiased parameter estimates in linear and quadratic growth models. Both LS and maximum likelihood estimators have similar variance characteristics. In simulation studies, these properties appear to extend to the case of moderately dependent measurement error. The methodology is illustrated by application to a tumor growth study for an ovarian cancer cell line.

  1. Consistency of Border-Ownership Cells across Artificial Stimuli, Natural Stimuli, and Stimuli with Ambiguous Contours.

    Science.gov (United States)

    Hesse, Janis K; Tsao, Doris Y

    2016-11-02

    Segmentation and recognition of objects in a visual scene are two problems that are hard to solve separately from each other. When segmenting an ambiguous scene, it is helpful to already know the present objects and their shapes. However, for recognizing an object in clutter, one would like to consider its isolated segment alone to avoid confounds from features of other objects. Border-ownership cells (Zhou et al., 2000) appear to play an important role in segmentation, as they signal the side-of-figure of artificial stimuli. The present work explores the role of border-ownership cells in dorsal macaque visual areas V2 and V3 in the segmentation of natural object stimuli and locally ambiguous stimuli. We report two major results. First, compared with previous estimates, we found a smaller percentage of cells that were consistent across artificial stimuli used previously. Second, we found that the average response of those neurons that did respond consistently to the side-of-figure of artificial stimuli also consistently signaled, as a population, the side-of-figure for borders of single faces, occluding faces and, with higher latencies, even stimuli with illusory contours, such as Mooney faces and natural faces completely missing local edge information. In contrast, the local edge or the outlines of the face alone could not always evoke a significant border-ownership signal. Our results underscore that border ownership is coded by a population of cells, and indicate that these cells integrate a variety of cues, including low-level features and global object context, to compute the segmentation of the scene.

  2. Stimuli, Reinforcers, and Private Events

    Science.gov (United States)

    Nevin, John A.

    2008-01-01

    Radical behaviorism considers private events to be a part of ongoing observable behavior and to share the properties of public events. Although private events cannot be measured directly, their roles in overt action can be inferred from mathematical models that relate private responses to external stimuli and reinforcers according to the same…

  3. Stimuli, Reinforcers, and Private Events

    Science.gov (United States)

    Nevin, John A.

    2008-01-01

    Radical behaviorism considers private events to be a part of ongoing observable behavior and to share the properties of public events. Although private events cannot be measured directly, their roles in overt action can be inferred from mathematical models that relate private responses to external stimuli and reinforcers according to the same…

  4. Determining the unsaturated hydraulic conductivity of a compacted sand-bentonite mixture under constant volume and free-swell conditions

    CERN Document Server

    Cui, Yu-Jun; Loiseau, Cyril; Delage, Pierre; 10.1016/j.pce.2008.10.017

    2008-01-01

    Highly compacted sand-bentonite mixtures are often considered as possible engineered barriers in deep high-level radioactive waste disposals. In-situ, the saturation of these barriers from their initially unsaturated state is a complex hydro-mechanical coupled process in which temperature effects also play a role. The key parameter of this process is the unsaturated hydraulic conductivity of the barrier. In this paper, isothermal infiltration experiments were conducted to determine the unsaturated hydraulic conductivity according to the instantaneous profile method. To do so, total suction changes were monitored at different locations along the soil specimen by using resistivity relative humidity probes. Three constant volume infiltration tests were conducted showing, unexpectedly, a decrease of the hydraulic conductivity during infiltration. One test performed under free-swell conditions showed the opposite and standard trend. These observations were interpreted in terms of microstructure changes during wett...

  5. Stimuli-Responsive Materials for Controlled Release Applications

    KAUST Repository

    Li, Song

    2015-04-01

    The controlled release of therapeutics has been one of the major challenges for scientists and engineers during the past three decades. To address this outstanding problem, the design and fabrication of stimuli-responsive materials are pursued to guarantee the controlled release of cargo at a specific time and with an accurate amount. Upon applying different stimuli such as light, magnetic field, heat, pH change, enzymes or redox, functional materials change their physicochemical properties through physical transformation or chemical reactions, allowing the release of payload agents on demand. This dissertation studied three stimuli-responsive membrane systems for controlled release from films of macro sizes to microcapsules of nano sizes. The first membrane system is a polymeric composite film which can decrease and sustain diffusion upon light irradiation. The photo-response of membranes is based on the photoreaction of cinnamic derivatives. The second one is composite membrane which can improve diffusion upon heating. The thermo-response of membranes comes from the volume phase transition ability of hydrogels. The third one is microcapsule which can release encapsulated agents upon light irradiation. The photo-response of capsules results from the photoreaction of nitrobenzyl derivatives. The study on these membrane systems reveals that stimuli-responsive release can be achieved by utilizing different functional materials on either macro or micro level. Based on the abundant family of smart materials, designing and fabricating stimuli-responsive systems shall lead to various advanced release processes on demand for biomedical applications.

  6. Gilthead seabream (Sparus aurata) response to three music stimuli (Mozart--"Eine Kleine Nachtmusik," Anonymous--"Romanza," Bach--"Violin Concerto No. 1") and white noise under recirculating water conditions.

    Science.gov (United States)

    Papoutsoglou, Sofronios E; Karakatsouli, Nafsika; Psarrou, Anna; Apostolidou, Sofia; Papoutsoglou, Eustratios S; Batzina, Alkisti; Leondaritis, Georgios; Sakellaridis, N

    2015-02-01

    This study presents the results of the response of Sparus aurata to three different musical stimuli, derived from the transmission (4 h per day, 5 days per week) of particular music pieces by Mozart, Romanza and Bach (140 dB(rms) re 1 μPa), compared to the same transmission level of white noise, while the underwater ambient noise in all the experimental tanks was 121 dB(rms) re 1 μPa. Using recirculating sea water facilities, 10 groups, 2 for each treatment, of 20 specimens of 11.2 ± 0.02 g (S.E.), were reared for 94 days, under 150 ± 10 l× 12L-12D, and were fed an artificial diet three times per day. Fish body weight showed significant differences after 55 days, while its maximum level was observed after the 69th day until the end of the experiment, the highest value demonstrated in Mozart (M) groups, followed by those of Romanza (R), Bach (B), control (C) and white noise (WN). SGR (M = B), %WG (M = B) and FCR (all groups fed same % b.w.) were also improved for M group. Brain neurotransmitters results exhibited significant differences in DA-dopamine, (M > B), 5HIAA (C > B), 5HIAA:5HT (WN > R), DOPAC (M > B), DOPAC:DA and (DOPAC + HVA):DA, (C > M), while no significant differences were observed in 5HT, NA, HVA and HVA:DA. No differences were observed in biometric measurements, protease activity, % fatty acids of fillet, visceral fat and liver, while differences were observed regarding carbohydrase activity and the amount (mg/g w.w.) of some fatty acids in liver, fillet and visceral fat. In conclusion, present results confirm those reported for S. aurata, concerning the observed relaxing influence--due to its brain neurotransmitters action--of the transmission of Mozart music (compared to R and B), which resulted in the achievement of maximum growth rate, body weight and improved FCR. This conclusion definitely supports the musical "understanding" and sensitivity of S. aurata to music stimuli as well as suggesting a specific effect of white noise.

  7. Stimuli-responsive cement-reinforced rubber.

    Science.gov (United States)

    Musso, Simone; Robisson, Agathe; Maheshwar, Sudeep; Ulm, Franz-Josef

    2014-05-14

    In this work, we report the successful development of a cement-rubber reactive composite with reversible mechanical properties. Initially, the composite behaves like rubber containing inert filler, but when exposed to water, it increases in volume and reaches a stiffness that is intermediate between that of hydrogenated nitrile butadiene rubber (HNBR) and hydrated cement, while maintaining a relatively large ductility characteristic of rubber. After drying, the modulus increases even further up to 400 MPa. Wet/drying cycles prove that the elastic modulus can reversibly change between 150 and 400 MPa. Utilizing attenuated total reflection Fourier transform infrared spectroscopy), we demonstrate that the high pH produced by the hydration of cement triggers the hydrolysis of the rubber nitrile groups into carboxylate anions. Thus, the salt bridges, generated between the carboxylate anions of the elastomer and the cations of the filler, are responsible for the reversible variations in volume and elastic modulus of the composite as a consequence of environmental moisture exposure. These results reveal that cement nanoparticles can successfully be used to accomplish a twofold task: (a) achieve an original postpolymerization modification that allows one to work with carboxylate HNBR (HXNBR) not obtained by direct copolymerization of carboxylate monomers with butadiene, and (b) synthesize a stimuli-responsive polymeric composite. This new type of material, having an ideal behavior for sealing application, could be used as an alternative to cement for oil field zonal isolation applications.

  8. The use of visual stimuli during auditory assessment.

    Science.gov (United States)

    Pearlman, R C; Cunningham, D R; Williamson, D G; Amerman, J D

    1975-01-01

    Two groups of male subjects beyond 50 years of age were given audiometric tasks with and without visual stimulation to determine if visual stimuli changed auditory perception. The first group consisted of 10 subjects with normal auditory acuity; the second, 10 with sensorineural hearing losses greater than 30 decibels. The rate of presentation of the visual stimuli, consisting of photographic slides of various subjects, was determined in experiment I of the study. The subjects, while viewing the slides at their own rate, took an audiotry speech discrimination test. Advisedly they changed the slides at a speed which they felt facilitated attention while performing the auditory task. The mean rate of slide-changing behavior was used as the "optimum" visual stimulation rate in experiment II, which was designed to explore the interaction of the bisensory presentation of stimuli. Bekesy tracings and Rush Hughes recordings were administered without and with visual stimuli, the latter presented at the mean rate of slide changes found in experiment I. Analysis of data indicated that (1) no statistically significant difference exists between visual and nonvisual conditions during speech discrimination and Bekesy testing; and (2) subjects did not believe that visual stimuli as presented in this study helped them to listen more effectively. The experimenter concluded that the various auditory stimuli encountered in the auditory test situation may actually be a deterrent to boredom because of the variety of tasks required in a testing situation.

  9. Emotional Stimuli and Motor Conversion Disorder

    Science.gov (United States)

    Voon, Valerie; Brezing, Christina; Gallea, Cecile; Ameli, Rezvan; Roelofs, Karin; LaFrance, W. Curt, Jr.; Hallett, Mark

    2010-01-01

    Conversion disorder is characterized by neurological signs and symptoms related to an underlying psychological issue. Amygdala activity to affective stimuli is well characterized in healthy volunteers with greater amygdala activity to both negative and positive stimuli relative to neutral stimuli, and greater activity to negative relative to…

  10. Subconscious Subliminal Stimuli And rrrsssssshhhppp!

    DEFF Research Database (Denmark)

    Lewis Brooks, Anthony

    2003-01-01

    in a ‘remarkable reductive retraction’ from ‘fixation centers’ such that a more human intuitive interaction to the ‘New World’ becomes apparent in design scenarios. Ubiquitous ‘Virtual Interactive Space’ (Brooks, 1999) will become a more utilized and higher resolution capture resource integrative to design...... of such issues as outlined in my opening statement. I suggest that successful design of the future will take much more into account the neural stimuli & potential subliminal synesthesia design aspects as an integrated element of the envisioned Virtual Interactive Space. Keywords: remarkable reductive retraction...

  11. Neural responses to smoking stimuli are influenced by smokers' attitudes towards their own smoking behaviour.

    Directory of Open Access Journals (Sweden)

    Bastian Stippekohl

    Full Text Available An important feature of addiction is the high drug craving that may promote the continuation of consumption. Environmental stimuli classically conditioned to drug-intake have a strong motivational power for addicts and can elicit craving. However, addicts differ in the attitudes towards their own consumption behavior: some are content with drug taking (consonant users whereas others are discontent (dissonant users. Such differences may be important for clinical practice because the experience of dissonance might enhance the likelihood to consider treatment. This fMRI study investigated in smokers whether these different attitudes influence subjective and neural responses to smoking stimuli. Based on self-characterization, smokers were divided into consonant and dissonant smokers. These two groups were presented smoking stimuli and neutral stimuli. Former studies have suggested differences in the impact of smoking stimuli depending on the temporal stage of the smoking ritual they are associated with. Therefore, we used stimuli associated with the beginning (BEGIN-smoking-stimuli and stimuli associated with the terminal stage (END-smoking-stimuli of the smoking ritual as distinct stimulus categories. Stimulus ratings did not differ between both groups. Brain data showed that BEGIN-smoking-stimuli led to enhanced mesolimbic responses (amygdala, hippocampus, insula in dissonant compared to consonant smokers. In response to END-smoking-stimuli, dissonant smokers showed reduced mesocortical responses (orbitofrontal cortex, subcallosal cortex compared to consonant smokers. These results suggest that smoking stimuli with a high incentive value (BEGIN-smoking-stimuli are more appetitive for dissonant than consonant smokers at least on the neural level. To the contrary, smoking stimuli with low incentive value (END-smoking-stimuli seem to be less appetitive for dissonant smokers than consonant smokers. These differences might be one reason why dissonant

  12. Cortical activation elicited by unrecognized stimuli

    Directory of Open Access Journals (Sweden)

    Badgaiyan Rajendra D

    2006-05-01

    Full Text Available Abstract Background It is unclear whether a stimulus that cannot be recognized consciously, could elicit a well-processed cognitive response. Methods We used functional imaging to examine the pattern of cortical activation elicited by unrecognized stimuli during memory processing. Subjects were given a recognition task using recognizable and non-recognizable subliminal stimuli. Results Unrecognized stimuli activated the cortical areas that are associated with retrieval attempt (left prefrontal, and novelty detection (left hippocampus. This indicates that the stimuli that were not consciously recognized, activated neural network associated with aspects of explicit memory processing. Conclusion Results suggest that conscious recognition of stimuli is not necessary for activation of cognitive processing.

  13. Volume de enxurrada e perda de solo em estradas florestais em condições de chuva natural Runoff volume and soil loss from forest roads under normal rainfall conditions

    Directory of Open Access Journals (Sweden)

    Alessandra Reis Garcia

    2003-08-01

    Full Text Available Foram determinados o volume total de água escoada e a perda de solo através da produção de sedimentos provenientes de segmentos de estradas florestais em condições de chuva natural, com diferentes valores de precipitações. As inclinações dos segmentos de 1 e 7% foram analisadas, enquanto os comprimentos variaram de 20 e 40 m, com 4 m de largura. Os segmentos de estrada foram delimitados com tábuas de 0,30 m de largura, envolvidas em lona plástica, para sua impermeabilização. Os dados de volume e intensidade de precipitação diária foram obtidos com a instalação de pluviômetro e pluviógrafo no local. O período de coleta de dados foi de um ano, concentrando-se na época das chuvas. O volume de enxurrada foi mais afetado pelo comprimento do segmento, ao passo que a massa de solo sofreu maior influência da declividade. A massa de solo erosinado cresceu exponencialmente em função do incremento do volume de enxurrada.The total runoff volume and soil loss caused by the production of sediments derived from forest road segments under normal rainfall conditions were determined. Segment slopes from 1 and 7% were analyzed, with segment lengths ranging from 20 and 40 m and width of 4 m. The road segments were marked with 0.30 m wide boards, protected with a plastic, waterproof film. Rainfall volume and intensity data were daily obtained by means of pluviometers and pluviographs. Data collection period was one year, concentrated in the rainy season. Runoff volume was most affected by segment length while soil loss was most affected by steepness. Soil sediment mass increased exponentially in function of the increased runoff volume.

  14. The Presentation of Olfactory-Trigeminal Mixed Stimuli Increases the Response to Subsequent Olfactory Stimuli.

    Science.gov (United States)

    Walliczek-Dworschak, Ute; Poncelet, Johan; Baum, Daniel; Baki, Ramona; Sinding, Charlotte; Warr, Jonathan; Hummel, Thomas

    2017-01-09

    The aim of this study was to evaluate the effect of (1) the addition of trigeminal stimuli to an olfactory stimulus and (2) the congruence in the odorous mixture after repeated odor presentation. Twenty-five normosmic volunteers were enrolled and presented stimulation blocks, consisting of three habituation stimuli (H) (orange odor), one dishabituation (DH) (control condition, orange odor; congruent condition, orange odor + CO2; incongruent condition, orange odor + l-isopulegol), and one dishabituated stimulus (D) (orange odor). Olfactory event-related potentials were analyzed. Response amplitudes differed significantly in the incongruent condition (N1P2 between H3 and D; peak to peak N1P2 at electrode positions Cz, Fz, and Pz; response amplitudes between H3 and DH). The addition of CO2 modified the perception of orange odor, pronouncing a fruity note, whereas the addition of l-isopulegol as a DH pronounced the l-isopulegol note. This study provides evidence that incongruent trigeminal-olfactory stimulants increase the response to subsequent olfactory stimulus.

  15. Miniaturized, High Flow, Low Dead Volume Pre-Concentrator for Trace Contaminants in Water under Microgravity Conditions Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Thorleaf Research, Inc. proposes to develop a miniaturized high flow, low dead-volume pre-concentrator for monitoring trace levels of contaminants in water under...

  16. conditions

    Directory of Open Access Journals (Sweden)

    M. Venkatesulu

    1996-01-01

    Full Text Available Solutions of initial value problems associated with a pair of ordinary differential systems (L1,L2 defined on two adjacent intervals I1 and I2 and satisfying certain interface-spatial conditions at the common end (interface point are studied.

  17. Sex-related memory recall and talkativeness for emotional stimuli

    Directory of Open Access Journals (Sweden)

    Benedetto eArnone

    2011-09-01

    Full Text Available Recent studies have evidenced an increasing interest in sex-related brain mechanisms and cerebral lateralization subserving emotional memory, language processing, and conversational behavior. We used event related potentials (ERP to examine the influence of sex and hemisphere on brain responses to emotional stimuli. Given that the P300 component of ERP is considered a cognitive neuroelectric phenomenon, we compared left and right hemisphere P300 responses to emotional stimuli in men and women. As indexed by both amplitude and latency measures, emotional stimuli elicited more robust P300 effects in the left hemisphere in women than in men, while a stronger P300 component was elicited in the right hemisphere in men compared to women. Our findings show that the variables of sex and hemisphere interacted significantly to influence the strength of the P300 component to the emotional stimuli. Emotional stimuli were also best recalled when given a long-term, incidental memory test, a fact potentially related to the differential P300 waves at encoding. Moreover, taking into account the sex-related differences in language processing and conversational behaviour, in the present study we evaluated possible talkativeness differences between the two genders in the recollection of emotional stimuli. Our data showed that women used a higher number of words, compared to men, to describe both arousal and neutral stories. Moreover, the present results support the view that sex differences in lateralization may not be a general feature of language processing but may be related to the specific condition, such as the emotional content of stimuli.

  18. Sex-related memory recall and talkativeness for emotional stimuli.

    Science.gov (United States)

    Arnone, Benedetto; Pompili, Assunta; Tavares, Maria Clotilde; Gasbarri, Antonella

    2011-01-01

    Recent studies have evidenced an increasing interest in sex-related brain mechanisms and cerebral lateralization subserving emotional memory, language processing, and conversational behavior. We used event-related-potentials (ERP) to examine the influence of sex and hemisphere on brain responses to emotional stimuli. Given that the P300 component of ERP is considered a cognitive neuroelectric phenomenon, we compared left and right hemisphere P300 responses to emotional stimuli in men and women. As indexed by both amplitude and latency measures, emotional stimuli elicited more robust P300 effects in the left hemisphere in women than in men, while a stronger P300 component was elicited in the right hemisphere in men compared to women. Our findings show that the variables of sex and hemisphere interacted significantly to influence the strength of the P300 component to the emotional stimuli. Emotional stimuli were also best recalled when given a long-term, incidental memory test, a fact potentially related to the differential P300 waves at encoding. Moreover, taking into account the sex-related differences in language processing and conversational behavior, in the present study we evaluated possible talkativeness differences between the two genders in the recollection of emotional stimuli. Our data showed that women used a higher number of words, compared to men, to describe both arousal and neutral stories. Moreover, the present results support the view that sex differences in lateralization may not be a general feature of language processing but may be related to the specific condition, such as the emotional content of stimuli.

  19. Trophic interactions among sympatric zooplanktivorous fish species in volume change conditions in a large, shallow, tropical lake

    Directory of Open Access Journals (Sweden)

    Rodrigo Moncayo-Estrada

    2011-03-01

    Full Text Available Significant reductions in the water volume of shallow lakes impose a restriction on species segregation promoting more interactions in the trophic relationships. The diets of three closely related zooplanktivorous silversides belonging to the Atherinopsidae species flock of lake Chapala , Mexico, were analyzed at two sites (Chirostoma jordani, C. labarcae, and C. consocium. Diets were described in critical shallow (August 2000 and volume recovery conditions (August 2005. Diets included mainly cladocerans (Bosmina, Ceriodaphnia, and Daphnia and copepods (Cyclops. A significant difference in diets was detected when comparing years (MRPP analysis, A = 0.22, p La reducción significativa en el volumen de agua de los lagos someros impone una restricción en la segregación de las especies y promueve una mayor interacción en las relaciones tróficas. Se analizó la dieta de tres especies cercanamente emparentadas de zooplanctívoros pertenecientes al flock de Aterinópsidos del lago de Chapala en dos sitios (Chirostoma jordani, C. labarcae y C. consocium. Las dieta fue descrita en una condición somera crítica (Agosto 2000 y en una condición de recuperación del lago (Agosto 2005. En la dieta se incluyen principalmente cladóceros (Bosmina, Ceriodaphnia y Daphnia y copépodos (Cyclops. Se detectó una diferencia significativa en la dieta cuando se comparan los años (análisis MRPP, A = 0.22, p < 0.0001 y los sitios en los diferentes años (análisis MRPP, A = 0.17, p = 0.004. De acuerdo a los valores promedio de amplitud de nicho, las especies fueron clasificadas como especialistas y consumidores intermediarios. En condiciones someras, el pequeño intervalo de la amplitud de nicho (1.72 a 3.64 y los altos valores del traslape de nicho (D = 0.64, L = 8.62 indicaron un alto potencial para una interacción explotativa inter-específica. Cuando el lago se recupera en su volumen, un incremento en el intervalo de amplitud de nicho (1.04 a 4.96 y los

  20. The relationship between open volume defects and deposition conditions of superconducting thin-film YBa sub 2 Cu sub 3 O sub 7 sub - sub x

    CERN Document Server

    Zhou, X Y; Jiang, H; Bauer-Kugelmann, W; Duffy, J A; Koegel, G; Triftshaeuser, W

    1997-01-01

    The relationship between the open volume defects and the deposition conditions of superconducting thin-film YBa sub 2 Cu sub 3 O sub 7 sub - sub x was studied by the position lifetime technique. Using a low-energy pulsed positron system, positron lifetime as a function of implantation energy was measured on epitaxial superconducting thin-film YBa sub 2 Cu sub 3 O sub 7 sub - sub x deposited on yttrium stabilized cubic zirconia substrates (YSZ) with pulsed laser deposition in a partial pressure of air under different conditions. The results show that the type of open volume defect is independent of deposition conditions such as the substrate temperature, T sub s , and the air pressure, P sub a. The defect concentration increases with decreasing T sub s and increasing P sub a. (author). Letter-to-the-editor

  1. Nanoparticle volume fraction with heat and mass transfer on MHD mixed convection flow in a nanofluid in the presence of thermo-diffusion under convective boundary condition

    Science.gov (United States)

    Kandasamy, R.; Jeyabalan, C.; Sivagnana Prabhu, K. K.

    2016-02-01

    This article examines the influence of thermophoresis, Brownian motion of the nanoparticles with variable stream conditions in the presence of magnetic field on mixed convection heat and mass transfer in the boundary layer region of a semi-infinite porous vertical plate in a nanofluid under the convective boundary conditions. The transformed boundary layer ordinary differential equations are solved numerically using Maple 18 software with fourth-fifth order Runge-Kutta-Fehlberg method. Numerical results are presented both in tabular and graphical forms illustrating the effects of these parameters with magnetic field on momentum, thermal, nanoparticle volume fraction and solutal concentration boundary layers. The numerical results obtained for the velocity, temperature, volume fraction, and concentration profiles reveal interesting phenomenon, some of these qualitative results are presented through plots. It is interesting to note that the magnetic field plays a dominant role on nanofluid flow under the convective boundary conditions.

  2. High-order finite-volume solutions of the steady-state advection-diffusion equation with nonlinear Robin boundary conditions

    Science.gov (United States)

    Lin, Zhi; Zhang, Qinghai

    2017-09-01

    We propose high-order finite-volume schemes for numerically solving the steady-state advection-diffusion equation with nonlinear Robin boundary conditions. Although the original motivation comes from a mathematical model of blood clotting, the nonlinear boundary conditions may also apply to other scientific problems. The main contribution of this work is a generic algorithm for generating third-order, fourth-order, and even higher-order explicit ghost-filling formulas to enforce nonlinear Robin boundary conditions in multiple dimensions. Under the framework of finite volume methods, this appears to be the first algorithm of its kind. Numerical experiments on boundary value problems show that the proposed fourth-order formula can be much more accurate and efficient than a simple second-order formula. Furthermore, the proposed ghost-filling formulas may also be useful for solving other partial differential equations.

  3. Response to various periods of mechanical stimuli in Physarum plasmodium

    Science.gov (United States)

    Umedachi, Takuya; Ito, Kentaro; Kobayashi, Ryo; Ishiguro, Akio; Nakagaki, Toshiyuki

    2017-06-01

    Response to mechanical stimuli is a fundamental and critical ability for living cells to survive in hazardous conditions or to form adaptive and functional structures against force(s) from the environment. Although this ability has been extensively studied by molecular biology strategies, it is also important to investigate the ability from the viewpoint of biological rhythm phenomena so as to reveal the mechanisms that underlie these phenomena. Here, we use the plasmodium of the true slime mold Physarum polycephalum as the experimental system for investigating this ability. The plasmodium was repetitively stretched for various periods during which its locomotion speed was observed. Since the plasmodium has inherent oscillation cycles of protoplasmic streaming and thickness variation, how the plasmodium responds to various periods of external stretching stimuli can shed light on the other biological rhythm phenomena. The experimental results show that the plasmodium exhibits response to periodic mechanical stimulation and changes its locomotion speed depending on the period of the stretching stimuli.

  4. Conscious perception of emotional stimuli: brain mechanisms.

    Science.gov (United States)

    Mitchell, Derek G V; Greening, Steven G

    2012-08-01

    Emotional stimuli are thought to gain rapid and privileged access to processing resources in the brain. The structures involved in this enhanced access are thought to support subconscious, reflexive processes. Whether these pathways contribute to the phenomenological experience of emotional visual awareness (i.e., conscious perception) is unclear. In this review, it is argued that subcortical networks associated with the rapid detection of emotionally salient stimuli also play a key role in shaping awareness. This proposal is based on the idea that awareness of visual stimuli should be considered along a continuum, having intermediate levels, rather than as an all-or-none construct. It is also argued that awareness of emotional stimuli requires less input from frontoparietal structures that are often considered crucial for visual awareness. Evidence is also presented that implicates a region of the medial prefrontal cortex, involved in emotion regulation, in modulating amygdala output to determine awareness of emotional visual stimuli; when emotional stimuli are present, the conscious perception of alternative stimuli requires greater regulatory influences from cortical structures. Thus, emotional stimuli are privileged not only for neuronal representation and impact on subconscious processes, but also for awareness, allowing humans to deal flexibly rather than merely reflexively to biologically significant stimuli.

  5. Influence of Meteorological Conditions on Changes in the Volume of the Pine Stem at the End of Vegetation Using High Resolution Dendrometers

    Directory of Open Access Journals (Sweden)

    Julius Taminskas

    2014-10-01

    Full Text Available Using dendrometers for measuring a radial increment of trees is efficient not only for investigation into the dynamics of the increment but also for changes in the tree stem in general, for a physiological condition of trees during certain periods of time, reliance on meteorological conditions and for tree-ring formation studies. The conducted research has applied to high resolution DRL 26 dendrometers that helped with identifying and distinguishing the impacts of climatic factors on the physiology and growth of trees. Also, the performed investigation assisted in assessing the impact of microclimate conditions on changes in tree stems. The location for installing dendrometers was selected with reference to the criteria such as representative research location, the degree of violation assessment, equal distribution of research sites in Lithuania and the estimation of climatic, hydrologic and anthropogenic conditions. Considering the above mentioned criteria, three raised bogs in which temperature, automatic water level devices in wells and dendrometers installed in measurement areas were chosen. The research period lasted from the end of the vegetation period to the beginning of dormancy season. For research purposes, 5 growing Scots pines (Pinus sylvestris were used for examining changes in the stem volume. Another objective was to find out how stems were affected by growing in bog surroundings and to analyse the synchronicity of volume changes between trees. The conducted research disclosed specific features of the dynamics of changes in the stem volume at the end of vegetation, and the beginning of dormancy season was found.

  6. Cardiorespiratory interactions to external stimuli.

    Science.gov (United States)

    Bernardi, L; Porta, C; Spicuzza, L; Sleight, P

    2005-09-01

    Respiration is a powerful modulator of heart rate variability, and of baro- or chemo-reflex sensitivity. This occurs via a mechanical effect of breathing that synchronizes all cardiovascular variables at the respiratory rhythm, particularly when this occurs at a particular slow rate coincident with the Mayer waves in arterial pressure (approximately 6 cycles/min). Recitation of the rosary prayer (or of most mantras), induces a marked enhancement of these slow rhythms, whereas random verbalization or random breathing does not. This phenomenon in turn increases baroreflex sensitivity and reduces chemoreflex sensitivity, leading to increases in parasympathetic and reductions in sympathetic activity. The opposite can be seen during either verbalization or mental stress tests. Qualitatively similar effects can be obtained even by passive listening to more or less rhythmic auditory stimuli, such as music, and the speed of the rhythm (rather than the style) appears to be one of the main determinants of the cardiovascular and respiratory responses. These findings have clinical relevance. Appropriate modulation of breathing, can improve/restore autonomic control of cardiovascular and respiratory systems in relevant diseases such as hypertension and heart failure, and might therefore help improving exercise tolerance, quality of life, and ultimately, survival.

  7. Determining the Optimal Number of Stimuli per Cranial Site during Transcranial Magnetic Stimulation Mapping

    Science.gov (United States)

    Schabrun, Siobhan M.

    2017-01-01

    The delivery of five stimuli to each cranial site is recommended during transcranial magnetic stimulation (TMS) mapping. However, this time-consuming practice restricts the use of TMS mapping beyond the research environment. While reducing the number of stimuli administered to each cranial site may improve efficiency and decrease physiological demand, doing so may also compromise the procedure's validity. Therefore, the aim of this study was to determine the minimum number of stimuli per cranial site required to obtain valid outcomes during TMS mapping. Map volume and centre of gravity (CoG) recordings obtained using five stimuli per cranial site were retrospectively compared to those obtained using one, two, three, and four stimuli per cranial site. For CoG longitude, one stimulus per cranial site produced valid recordings (ICC = 0.91, 95% CI 0.82 to 0.95). However, this outcome is rarely explored in isolation. As two stimuli per cranial site were required to obtain valid CoG latitude (ICC = 0.99, 95% CI 0.99 to 0.99) and map volume (ICC = 0.99, 95% CI 0.99 to 0.99) recordings, it is recommended that a minimum of two stimuli be delivered to each cranial site during TMS mapping in order to obtain valid outcomes. PMID:28331848

  8. Condition-dependent cell volume and concentration of Escherichia coli to facilitate data conversion for systems biology modeling

    NARCIS (Netherlands)

    Volkmer, Benjamin; Heinemann, Matthias

    2011-01-01

    Systems biology modeling typically requires quantitative experimental data such as intracellular concentrations or copy numbers per cell. In order to convert population-averaging omics measurement data to intracellular concentrations or cellular copy numbers, the total cell volume and number of cell

  9. Effective stimuli for constructing reliable neuron models.

    Directory of Open Access Journals (Sweden)

    Shaul Druckmann

    2011-08-01

    Full Text Available The rich dynamical nature of neurons poses major conceptual and technical challenges for unraveling their nonlinear membrane properties. Traditionally, various current waveforms have been injected at the soma to probe neuron dynamics, but the rationale for selecting specific stimuli has never been rigorously justified. The present experimental and theoretical study proposes a novel framework, inspired by learning theory, for objectively selecting the stimuli that best unravel the neuron's dynamics. The efficacy of stimuli is assessed in terms of their ability to constrain the parameter space of biophysically detailed conductance-based models that faithfully replicate the neuron's dynamics as attested by their ability to generalize well to the neuron's response to novel experimental stimuli. We used this framework to evaluate a variety of stimuli in different types of cortical neurons, ages and animals. Despite their simplicity, a set of stimuli consisting of step and ramp current pulses outperforms synaptic-like noisy stimuli in revealing the dynamics of these neurons. The general framework that we propose paves a new way for defining, evaluating and standardizing effective electrical probing of neurons and will thus lay the foundation for a much deeper understanding of the electrical nature of these highly sophisticated and non-linear devices and of the neuronal networks that they compose.

  10. Vestibular rehabilitation with visual stimuli in peripheral vestibular disorders

    Directory of Open Access Journals (Sweden)

    Andréa Manso

    2016-04-01

    Full Text Available ABSTRACT INTRODUCTION: Visual stimuli can induce vestibular adaptation and recovery of body balance. OBJECTIVE: To verify the effect of visual stimuli by digital images on vestibular and body balance rehabilitation of peripheral vestibular disorders. METHODS: Clinical, randomized, prospective study. Forty patients aged between 23 and 63 years with chronic peripheral vestibular disorders underwent 12 sessions of rehabilitation with visual stimuli using digital video disk (DVD (experimental group or Cawthorne-Cooksey exercises (control group. The Dizziness Handicap Inventory (DHI, dizziness analog scale, and the sensitized Romberg static balance and one-leg stance tests were applied before and after the intervention. RESULTS: Before and after the intervention, there was no difference between the experimental and control groups (p > 0.005 regarding the findings of DHI, dizziness analog scale, and static balance tests. After the intervention, the experimental and control groups showed lower values (p < 0.05 in the DHI and the dizziness analog scale, and higher values (p < 0.05 in the static balance tests in some of the assessed conditions. CONCLUSION: The inclusion of visual stimuli by digital images on vestibular and body balance rehabilitation is effective in reducing dizziness and improving quality of life and postural control in individuals with peripheral vestibular disorders.

  11. Cognitive control modulates preferential sensory processing of affective stimuli.

    Science.gov (United States)

    Steinhauser, Marco; Flaisch, Tobias; Meinzer, Marcus; Schupp, Harald T

    2016-10-01

    Adaptive human behavior crucially relies on the ability of the brain to allocate resources automatically to emotionally significant stimuli. This ability has consistently been demonstrated by studies showing preferential processing of affective stimuli in sensory cortical areas. It is still unclear, however, whether this putatively automatic mechanism can be modulated by cognitive control processes. Here, we use functional magnetic resonance imaging (fMRI) to investigate whether preferential processing of an affective face distractor is suppressed when an affective distractor has previously elicited a response conflict in a word-face Stroop task. We analyzed this for three consecutive stages in the ventral stream of visual processing for which preferential processing of affective stimuli has previously been demonstrated: the striate area (BA 17), category-unspecific extrastriate areas (BA 18/19), and the fusiform face area (FFA). We found that response conflict led to a selective suppression of affective face processing in category-unspecific extrastriate areas and the FFA, and this effect was accompanied by changes in functional connectivity between these areas and the rostral anterior cingulate cortex. In contrast, preferential processing of affective face distractors was unaffected in the striate area. Our results indicate that cognitive control processes adaptively suppress preferential processing of affective stimuli under conditions where affective processing is detrimental because it elicits response conflict.

  12. Dopamine encoding of Pavlovian incentive stimuli diminishes with extended training.

    Science.gov (United States)

    Clark, Jeremy J; Collins, Anne L; Sanford, Christina Akers; Phillips, Paul E M

    2013-02-20

    Dopamine is highly implicated both as a teaching signal in reinforcement learning and in motivating actions to obtain rewards. However, theoretical disconnects remain between the temporal encoding properties of dopamine neurons and the behavioral consequences of its release. Here, we demonstrate in rats that dopamine evoked by Pavlovian cues increases during acquisition, but dissociates from stable conditioned appetitive behavior as this signal returns to preconditioning levels with extended training. Experimental manipulation of the statistical parameters of the behavioral paradigm revealed that this attenuation of cue-evoked dopamine release during the postasymptotic period was attributable to acquired knowledge of the temporal structure of the task. In parallel, conditioned behavior became less dopamine dependent after extended training. Thus, the current work demonstrates that as the presentation of reward-predictive stimuli becomes anticipated through the acquisition of task information, there is a shift in the neurobiological substrates that mediate the motivational properties of these incentive stimuli.

  13. Cell volume regulation in the perfused liver of a freshwater air-breathing catfish Clarias batrachus under aniso-osmotic conditions: Roles of inorganic ions and taurine

    Indian Academy of Sciences (India)

    Carina Goswami; Nirmalendu Saha

    2006-12-01

    The roles of various inorganic ions and taurine, an organic osmolyte, in cell volume regulation were investigated in the perfused liver of a freshwater air-breathing catfish Clarias batrachus under aniso-osmotic conditions. There was a transient increase and decrease of liver cell volume following hypotonic (–80 mOsmol/l) and hypertonic (+80 mOsmol/l) exposures, respectively, which gradually decreased/increased near to the control level due to release/uptake of water within a period of 25–30 min. Liver volume decrease was accompanied by enhanced efflux of K+ (9.45 ± 0.54 mol/g liver) due to activation of Ba2+- and quinidine-sensitive K+ channel, and to a lesser extent due to enhanced efflux of Cl¯ (4.35 ± 0.25 mol/g liver) and Na+ (3.68 ± 0.37 mol/g liver). Conversely, upon hypertonic exposure, there was amiloride- and ouabain-sensitive uptake of K+ (9.78 ± 0.65 mol/g liver), and also Cl¯ (3.72 ± 0.25 mol/g liver). The alkalization/acidification of the liver effluents under hypo-/hypertonicity was mainly due to movement of various ions during volume regulatory processes. Taurine, an important organic osmolyte, appears also to play a very important role in hepatocyte cell volume regulation in the walking catfish as evidenced by the fact that hypo- and hyper-osmolarity caused transient efflux (5.68 ± 0.38 mol/g liver) and uptake (6.38 ± 0.45 mol/g liver) of taurine, respectively. The taurine efflux was sensitive to 4,4′-di-isothiocyanatostilbene-2,2′-disulphonic acid (DIDS, an anion channel blocker), but the uptake was insensitive to DIDS, thus indicating that the release and uptake of taurine during volume regulatory processes are unidirectional. Although the liver of walking catfish possesses the RVD and RVI mechanisms, it is to be noted that liver cells remain partly swollen and shrunken during anisotonic exposures, thereby possibly causing various volume-sensitive metabolic changes in the liver as reported earlier.

  14. Modeling auditory evoked potentials to complex stimuli

    DEFF Research Database (Denmark)

    Rønne, Filip Munch

    The auditory evoked potential (AEP) is an electrical signal that can be recorded from electrodes attached to the scalp of a human subject when a sound is presented. The signal is considered to reflect neural activity in response to the acoustic stimulation and is a well established clinical...... clinically and in research towards using realistic and complex stimuli, such as speech, to electrophysiologically assess the human hearing. However, to interpret the AEP generation to complex sounds, the potential patterns in response to simple stimuli needs to be understood. Therefore, the model was used...... to simulate auditory brainstem responses (ABRs) evoked by classic stimuli like clicks, tone bursts and chirps. The ABRs to these simple stimuli were compared to literature data and the model was shown to predict the frequency dependence of tone-burst ABR wave-V latency and the level-dependence of ABR wave...

  15. Modeling Stimuli-Responsive Nanoparticle Monolayer

    Science.gov (United States)

    Yong, Xin

    2015-03-01

    Using dissipative particle dynamics (DPD), we model a monolayer formed at the water-oil interface, which comprises stimuli-responsive nanoparticles. The solid core of the nanoparticle encompasses beads arranged in an fcc lattice structure and its surface is uniformly grafted with stimuli-responsive polymer chains. The surface-active nanoparticles adsorb to the interface from the suspension to minimize total energy of the system and create a monolayer covering the interface. We investigate the monolayer formation by characterizing the detailed adsorption kinetics. We explore the microstructure of the monolayer at different surface coverage, including the particle crowding and ordering, and elucidate the response of monolayer to external stimuli. The collective behavior of the particles within the monolayer is demonstrated quantitatively by vector-vector autocorrelation functions. This study provides a fundamental understanding of the interfacial behavior of stimuli-responsive nanoparticles.

  16. Cortical responses from adults and infants to complex visual stimuli.

    Science.gov (United States)

    Schulman-Galambos, C; Galambos, R

    1978-10-01

    Event-related potentials (ERPs) time-locked to the onset of visual stimuli were extracted from the EEG of normal adult (N = 16) and infant (N = 23) subjects. Subjects were not required to make any response. Stimuli delivered to the adults were 150 msec exposures of 2 sets of colored slides projected in 4 blocks, 2 in focus and 2 out of focus. Infants received 2-sec exposures of slides showing people, colored drawings or scenes from Disneyland, as well as 2-sec illuminations of the experimenter as she played a game or of a TV screen the baby was watching. The adult ERPs showed 6 waves (N1 through P4) in the 140--600-msec range; this included a positive wave at around 350 msec that was large when the stimuli were focused and smaller when they were not. The waves in the 150--200-msec range, by contrast, steadily dropped in amplitude as the experiment progressed. The infant ERPs differed greatly from the adult ones in morphology, usually showing a positive (latency about 200 msec)--negative(5--600msec)--positive(1000msec) sequence. This ERP appeared in all the stimulus conditions; its presence or absence, furthermore, was correlated with whether or not the baby seemed interested in the stimuli. Four infants failed to produce these ERPs; an independent measure of attention to the stimuli, heart rate deceleration, was demonstrated in two of them. An electrode placed beneath the eye to monitor eye movements yielded ERPs closely resembling those derived from the scalp in most subjects; reasons are given for assigning this response to activity in the brain, probably at the frontal pole. This study appears to be one of the first to search for cognitive 'late waves' in a no-task situation. The results suggest that further work with such task-free paradigms may yield additional useful techniques for studying the ERP.

  17. Preparing to grasp emotionally laden stimuli.

    Directory of Open Access Journals (Sweden)

    Laura Alice Santos de Oliveira

    Full Text Available BACKGROUND: Contemporary theories of motor control propose that motor planning involves the prediction of the consequences of actions. These predictions include the associated costs as well as the rewarding nature of movements' outcomes. Within the estimation of these costs and rewards would lie the valence, that is, the pleasantness or unpleasantness of a given stimulus with which one is about to interact. The aim of this study was to test if motor preparation encompasses valence. METHODOLOGY/PRINCIPAL FINDINGS: The readiness potential, an electrophysiological marker of motor preparation, was recorded before the grasping of pleasant, neutral and unpleasant stimuli. Items used were balanced in weight and placed inside transparent cylinders to prompt a similar grip among trials. Compared with neutral stimuli, the grasping of pleasant stimuli was preceded by a readiness potential of lower amplitude, whereas that of unpleasant stimuli was associated with a readiness potential of higher amplitude. CONCLUSIONS/SIGNIFICANCE: We show for the first time that the sensorimotor cortex activity preceding the grasping of a stimulus is affected by its valence. Smaller readiness potential amplitudes found for pleasant stimuli could imply in the recruitment of pre-set motor repertoires, whereas higher amplitudes found for unpleasant stimuli would emerge from a discrepancy between the required action and their aversiveness. Our results indicate that the prediction of action outcomes encompasses an estimate of the valence of a stimulus with which one is about to interact.

  18. Preparing to Grasp Emotionally Laden Stimuli

    Science.gov (United States)

    de Oliveira, Laura Alice Santos; Imbiriba, Luís Aureliano; Russo, Maitê Mello; Nogueira-Campos, Anaelli A.; Rodrigues, Erika de C.; Pereira, Mirtes G.; Volchan, Eliane; Vargas, Cláudia Domingues

    2012-01-01

    Background Contemporary theories of motor control propose that motor planning involves the prediction of the consequences of actions. These predictions include the associated costs as well as the rewarding nature of movements’ outcomes. Within the estimation of these costs and rewards would lie the valence, that is, the pleasantness or unpleasantness of a given stimulus with which one is about to interact. The aim of this study was to test if motor preparation encompasses valence. Methodology/Principal Findings The readiness potential, an electrophysiological marker of motor preparation, was recorded before the grasping of pleasant, neutral and unpleasant stimuli. Items used were balanced in weight and placed inside transparent cylinders to prompt a similar grip among trials. Compared with neutral stimuli, the grasping of pleasant stimuli was preceded by a readiness potential of lower amplitude, whereas that of unpleasant stimuli was associated with a readiness potential of higher amplitude. Conclusions/Significance We show for the first time that the sensorimotor cortex activity preceding the grasping of a stimulus is affected by its valence. Smaller readiness potential amplitudes found for pleasant stimuli could imply in the recruitment of pre-set motor repertoires, whereas higher amplitudes found for unpleasant stimuli would emerge from a discrepancy between the required action and their aversiveness. Our results indicate that the prediction of action outcomes encompasses an estimate of the valence of a stimulus with which one is about to interact. PMID:23024811

  19. Effects of Simulated Surface Effect Ship Motions on Crew Habitability. Phase II. Volume 2. Facility, Test conditions, and Schedules

    Science.gov (United States)

    1977-05-01

    CLASSIFICATION OF THIS PAGE 18. SUPPLEMENTARY NOTES (continued) motion on crew health and performance. Other organizacions preparing the companion...Rzr-- =lft In summary,, the living conditions in these cabins were cramped but not too unpleasant in ambient temperature and noise level

  20. Safe use of mine winding ropes, volume 4: studies towards a code of practice for rope condition assessment.

    CSIR Research Space (South Africa)

    Borrello, M

    1996-06-01

    Full Text Available The aim of this investigation was the verification of the code of Practice for Rope Condition Assessment. Ropes were meant to be discarded according to the discard criteria as outlined in the code and then tested by the CSIR. The results...

  1. A simple and rational numerical method of two-phase flow with volume-junction model. 1. Verification calculation in saturated condition

    Energy Technology Data Exchange (ETDEWEB)

    Okazaki, Motoaki [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1997-11-01

    A new numerical method to achieve a rigorous numerical calculation of each phase using a simple explicit method with volume-junction model is proposed. For this purpose, difference equations for numerical use are carefully derived so as to preserve the physical meaning of the basic equations. Specifically, momentum equations for the flow in the volume are newly derived to keep strict conservation of energy within the volume. To prove the validity of the numerical method and of previously proposed basic equations, including the original phase change equations, which were rigorously derived, some numerical calculations were made for each phase independently to examine the correctness of calculated results. The numerical calculation is advanced by simple integration of an explicitly obtained solution of difference equations without any special treatment. Calculated results of density and specific internal energy of each phase for saturated two-phase blowdown behavior are consistent for two different solution scheme as described below. Further, no accumulation of error in mass or energy was found. These results prove the consistency among basic equations, including phase change equations, and the correctness of numerical calculation method. The two different solution schemes used were: (1) solutions of pressure and void fraction in saturated condition were obtained by using mass conservation equation of each phase simultaneously, and (2) fluid properties were calculated directly from mass and energy conservation equation of each phase. (author)

  2. Fertility of beef cattle females with mating stimuli around insemination.

    Science.gov (United States)

    Rodriguez, R O; Rivera, M J

    1999-01-29

    An experiment was conducted to test the hypothesis that sterile mounts around insemination improves pregnancy rate to artificial insemination (AI) and to define the effects of age, season, time to complete AI and time of day of insemination. A total of 178 Simbrah females were randomly assigned by calving date and body condition to one of three treatments during two consecutive years: (1) mating stimuli with a sterile bull at the time the cows were detected in estrus; (2) mating stimuli immediately after completing AI; (3) without mating stimuli. All cows and heifers were maintained under the same conditions of handling and feeding within the two breeding seasons (winter 1995 and summer 1996). Vasectomized bulls were used for the sterile mounts. Cows and heifers that were given a sterile mount at the time of detection of estrus, had an increased pregnancy rate (60.0%) compared with females given a sterile mount after completing AI (25.4%) or females without the sterile mount (35.6%) (P 0.05). Therefore, there is a biostimulatory effect of mating at the time beef cattle females are detected in estrus, on pregnancy rates to AI.

  3. Commercialization of air conditioning heat pump/water heater. Final technical report, Volume 2: Appendix A through E

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-01-30

    This is the final technical report on a commercialization project for an air conditioning heat pump water heater. The objective of the project was to produce a saleable system which would be economically competitive with natural gas and cost effective with regard to initial cost versus annual operating costs. The development and commercialization of the system is described. Compiled data included in numerous figures, tables and graphs.

  4. Generalization of the disruptive effects of alternative stimuli when combined with target stimuli in extinction.

    Science.gov (United States)

    Podlesnik, Christopher A; Miranda-Dukoski, Ludmila; Jonas Chan, C K; Bland, Vikki J; Bai, John Y H

    2017-09-01

    Differential-reinforcement treatments reduce target problem behavior in the short term but at the expense of making it more persistent long term. Basic and translational research based on behavioral momentum theory suggests that combining features of stimuli governing an alternative response with the stimuli governing target responding could make target responding less persistent. However, changes to the alternative stimulus context when combining alternative and target stimuli could diminish the effectiveness of the alternative stimulus in reducing target responding. In an animal model with pigeons, the present study reinforced responding in the presence of target and alternative stimuli. When combining the alternative and target stimuli during extinction, we altered the alternative stimulus through changes in line orientation. We found that (1) combining alternative and target stimuli in extinction more effectively decreased target responding than presenting the target stimulus on its own; (2) combining these stimuli was more effective in decreasing target responding trained with lower reinforcement rates; and (3) changing the alternative stimulus reduced its effectiveness when it was combined with the target stimulus. Therefore, changing alternative stimuli (e.g., therapist, clinical setting) during behavioral treatments that combine alternative and target stimuli could reduce the effectiveness of those treatments in disrupting problem behavior. © 2017 Society for the Experimental Analysis of Behavior.

  5. Stimuli-responsive smart gating membranes.

    Science.gov (United States)

    Liu, Zhuang; Wang, Wei; Xie, Rui; Ju, Xiao-Jie; Chu, Liang-Yin

    2016-02-07

    Membranes are playing paramount roles in the sustainable development of myriad fields such as energy, environmental and resource management, and human health. However, the unalterable pore size and surface properties of traditional porous membranes restrict their efficient applications. The performances of traditional membranes will be weakened upon unavoidable membrane fouling, and they cannot be applied to cases where self-regulated permeability and selectivity are required. Inspired by natural cell membranes with stimuli-responsive channels, artificial stimuli-responsive smart gating membranes are developed by chemically/physically incorporating stimuli-responsive materials as functional gates into traditional porous membranes, to provide advanced functions and enhanced performances for breaking the bottlenecks of traditional membrane technologies. Smart gating membranes, integrating the advantages of traditional porous membrane substrates and smart functional gates, can self-regulate their permeability and selectivity via the flexible adjustment of pore sizes and surface properties based on the "open/close" switch of the smart gates in response to environmental stimuli. This tutorial review summarizes the recent developments in stimuli-responsive smart gating membranes, including the design strategies and the fabrication strategies that are based on the introduction of the stimuli-responsive gates after or during membrane formation, and the positively and negatively responsive gating models of versatile stimuli-responsive smart gating membranes, as well as the advanced applications of smart gating membranes for regulating substance concentration in reactors, controlling the release rate of drugs, separating active molecules based on size or affinity, and the self-cleaning of membrane surfaces. With self-regulated membrane performances, smart gating membranes show great power for use in global sustainable development.

  6. Gender differences in detecting unanticipated stimuli: an ERP study.

    Science.gov (United States)

    Jin, Yan; Yan, Ke; Zhang, Yuhe; Jiang, Yijie; Tao, Ran; Zheng, Xifu

    2013-03-22

    The aim of the present study was to investigate the gender differences during an emotional anticipation task. Sixteen females and sixteen males participated in the experiment. Event-related potentials (ERPs) were measured in a modified cue-target paradigm and were recorded following stimuli that differed in two dimensions: (1) predictable vs. unpredictable pictures and (2) negative vs. neutral pictures. Cue-induced ERP results demonstrated that females had enhanced positive component (P2) compared to males. Moreover, results showed that during the unpredictable condition, females displayed larger P2 amplitudes in negative and neutral anticipation than males. This study demonstrates that females have greater sensitivity to the unanticipated stimuli, which may contribute to evolution.

  7. Auditory stimuli mimicking ambient sounds drive temporal "delta-brushes" in premature infants.

    Directory of Open Access Journals (Sweden)

    Mathilde Chipaux

    Full Text Available In the premature infant, somatosensory and visual stimuli trigger an immature electroencephalographic (EEG pattern, "delta-brushes," in the corresponding sensory cortical areas. Whether auditory stimuli evoke delta-brushes in the premature auditory cortex has not been reported. Here, responses to auditory stimuli were studied in 46 premature infants without neurologic risk aged 31 to 38 postmenstrual weeks (PMW during routine EEG recording. Stimuli consisted of either low-volume technogenic "clicks" near the background noise level of the neonatal care unit, or a human voice at conversational sound level. Stimuli were administrated pseudo-randomly during quiet and active sleep. In another protocol, the cortical response to a composite stimulus ("click" and voice was manually triggered during EEG hypoactive periods of quiet sleep. Cortical responses were analyzed by event detection, power frequency analysis and stimulus locked averaging. Before 34 PMW, both voice and "click" stimuli evoked cortical responses with similar frequency-power topographic characteristics, namely a temporal negative slow-wave and rapid oscillations similar to spontaneous delta-brushes. Responses to composite stimuli also showed a maximal frequency-power increase in temporal areas before 35 PMW. From 34 PMW the topography of responses in quiet sleep was different for "click" and voice stimuli: responses to "clicks" became diffuse but responses to voice remained limited to temporal areas. After the age of 35 PMW auditory evoked delta-brushes progressively disappeared and were replaced by a low amplitude response in the same location. Our data show that auditory stimuli mimicking ambient sounds efficiently evoke delta-brushes in temporal areas in the premature infant before 35 PMW. Along with findings in other sensory modalities (visual and somatosensory, these findings suggest that sensory driven delta-brushes represent a ubiquitous feature of the human sensory cortex

  8. Expectation and conditioning

    Science.gov (United States)

    Coster, Adelle C. F.; Alstrøm, Preben

    2001-02-01

    We present a dynamical model that embodies both classical and instrumental conditioning paradigms in the same framework. The model is based on the formation of expectations of stimuli and of rewards. The expectations of stimuli are formed in a recurrent process called expectation learning in which one activity pattern evokes another. The expectation of rewards or punishments (motivation) is modelled using reinforcement learning.

  9. VEP Responses to Op-Art Stimuli.

    Directory of Open Access Journals (Sweden)

    Louise O'Hare

    Full Text Available Several types of striped patterns have been reported to cause adverse sensations described as visual discomfort. Previous research using op-art-based stimuli has demonstrated that spurious eye movement signals can cause the experience of illusory motion, or shimmering effects, which might be perceived as uncomfortable. Whilst the shimmering effects are one cause of discomfort, another possible contributor to discomfort is excessive neural responses: As striped patterns do not have the statistical redundancy typical of natural images, they are perhaps unable to be encoded efficiently. If this is the case, then this should be seen in the amplitude of the EEG response. This study found that stimuli that were judged to be most comfortable were also those with the lowest EEG amplitude. This provides some support for the idea that excessive neural responses might also contribute to discomfort judgements in normal populations, in stimuli controlled for perceived contrast.

  10. VEP Responses to Op-Art Stimuli.

    Science.gov (United States)

    O'Hare, Louise; Clarke, Alasdair D F; Pollux, Petra M J

    2015-01-01

    Several types of striped patterns have been reported to cause adverse sensations described as visual discomfort. Previous research using op-art-based stimuli has demonstrated that spurious eye movement signals can cause the experience of illusory motion, or shimmering effects, which might be perceived as uncomfortable. Whilst the shimmering effects are one cause of discomfort, another possible contributor to discomfort is excessive neural responses: As striped patterns do not have the statistical redundancy typical of natural images, they are perhaps unable to be encoded efficiently. If this is the case, then this should be seen in the amplitude of the EEG response. This study found that stimuli that were judged to be most comfortable were also those with the lowest EEG amplitude. This provides some support for the idea that excessive neural responses might also contribute to discomfort judgements in normal populations, in stimuli controlled for perceived contrast.

  11. Stimuli responsive nanomaterials for controlled release applications

    KAUST Repository

    Li, Song

    2012-01-01

    The controlled release of therapeutics has been one of the major challenges for scientists and engineers during the past three decades. Coupled with excellent biocompatibility profiles, various nanomaterials have showed great promise for biomedical applications. Stimuli-responsive nanomaterials guarantee the controlled release of cargo to a given location, at a specific time, and with an accurate amount. In this review, we have combined the major stimuli that are currently used to achieve the ultimate goal of controlled and targeted release by "smart" nanomaterials. The most heavily explored strategies include (1) pH, (2) enzymes, (3) redox, (4) magnetic, and (5) light-triggered release.

  12. The Potential of Stimuli-Responsive Nanogels in Drug and Active Molecule Delivery for Targeted Therapy

    Directory of Open Access Journals (Sweden)

    Marta Vicario-de-la-Torre

    2017-05-01

    Full Text Available Nanogels (NGs are currently under extensive investigation due to their unique properties, such as small particle size, high encapsulation efficiency and protection of active agents from degradation, which make them ideal candidates as drug delivery systems (DDS. Stimuli-responsive NGs are cross-linked nanoparticles (NPs, composed of polymers, natural, synthetic, or a combination thereof that can swell by absorption (uptake of large amounts of solvent, but not dissolve due to the constituent structure of the polymeric network. NGs can undergo change from a polymeric solution (swell form to a hard particle (collapsed form in response to (i physical stimuli such as temperature, ionic strength, magnetic or electric fields; (ii chemical stimuli such as pH, ions, specific molecules or (iii biochemical stimuli such as enzymatic substrates or affinity ligands. The interest in NGs comes from their multi-stimuli nature involving reversible phase transitions in response to changes in the external media in a faster way than macroscopic gels or hydrogels due to their nanometric size. NGs have a porous structure able to encapsulate small molecules such as drugs and genes, then releasing them by changing their volume when external stimuli are applied.

  13. Startle auditory stimuli enhance the performance of fast dynamic contractions.

    Science.gov (United States)

    Fernandez-Del-Olmo, Miguel; Río-Rodríguez, Dan; Iglesias-Soler, Eliseo; Acero, Rafael M

    2014-01-01

    Fast reaction times and the ability to develop a high rate of force development (RFD) are crucial for sports performance. However, little is known regarding the relationship between these parameters. The aim of this study was to investigate the effects of auditory stimuli of different intensities on the performance of a concentric bench-press exercise. Concentric bench-presses were performed by thirteen trained subjects in response to three different conditions: a visual stimulus (VS); a visual stimulus accompanied by a non-startle auditory stimulus (AS); and a visual stimulus accompanied by a startle auditory stimulus (SS). Peak RFD, peak velocity, onset movement, movement duration and electromyography from pectoralis and tricep muscles were recorded. The SS condition induced an increase in the RFD and peak velocity and a reduction in the movement onset and duration, in comparison with the VS and AS condition. The onset activation of the pectoralis and tricep muscles was shorter for the SS than for the VS and AS conditions. These findings point out to specific enhancement effects of loud auditory stimulation on the rate of force development. This is of relevance since startle stimuli could be used to explore neural adaptations to resistance training.

  14. Computer programming for generating visual stimuli.

    Science.gov (United States)

    Bukhari, Farhan; Kurylo, Daniel D

    2008-02-01

    Critical to vision research is the generation of visual displays with precise control over stimulus metrics. Generating stimuli often requires adapting commercial software or developing specialized software for specific research applications. In order to facilitate this process, we give here an overview that allows nonexpert users to generate and customize stimuli for vision research. We first give a review of relevant hardware and software considerations, to allow the selection of display hardware, operating system, programming language, and graphics packages most appropriate for specific research applications. We then describe the framework of a generic computer program that can be adapted for use with a broad range of experimental applications. Stimuli are generated in the context of trial events, allowing the display of text messages, the monitoring of subject responses and reaction times, and the inclusion of contingency algorithms. This approach allows direct control and management of computer-generated visual stimuli while utilizing the full capabilities of modern hardware and software systems. The flowchart and source code for the stimulus-generating program may be downloaded from www.psychonomic.org/archive.

  15. From surface to volume plasmons in hyperbolic metamaterials: General existence conditions for bulk high-k waves in metal-dielectric and graphene-dielectric multilayers

    CERN Document Server

    Zhukovsky, Sergei V; Sipe, J E; Lavrinenko, Andrei V

    2014-01-01

    We theoretically investigate general existence conditions for broadband bulk large-wavevector (high-k) propagating waves (such as volume plasmon polaritons in hyperbolic metamaterials) in subwavelength periodic multilayer structures. Describing the elementary excitation in the unit cell of the structure by a generalized resonance pole of a reflection coefficient, and using Bloch's theorem, we derive analytical expressions for the band of large-wavevector propagating solutions. We apply our formalism to determine the high-k band existence in two important cases: the well-known metal-dielectric, and recently introduced graphene-dielectric stacks. We confirm that short-range surface plasmons in thin metal layers can give rise to hyperbolic metamaterial properties, and demonstrate that long-range surface plasmons cannot. We also show that graphene-dielectric multilayers tend to support high-k waves and explore the range of parameters for which this is possible, confirming the prospects of using graphene for mater...

  16. Volume-translated cubic EoS and PC-SAFT density models and a free volume-based viscosity model for hydrocarbons at extreme temperature and pressure conditions

    Energy Technology Data Exchange (ETDEWEB)

    Burgess, Ward A.; Tapriyal, Deepak; Morreale, Bryan D.; Soong, Yee; Baled, Hseen O.; Enick, Robert M.; Wu, Yue; Bamgbade, Babatunde A.; McHugh, Mark A.

    2013-12-01

    This research focuses on providing the petroleum reservoir engineering community with robust models of hydrocarbon density and viscosity at the extreme temperature and pressure conditions (up to 533 K and 276 MPa, respectively) characteristic of ultra-deep reservoirs, such as those associated with the deepwater wells in the Gulf of Mexico. Our strategy is to base the volume-translated (VT) Peng–Robinson (PR) and Soave–Redlich–Kwong (SRK) cubic equations of state (EoSs) and perturbed-chain, statistical associating fluid theory (PC-SAFT) on an extensive data base of high temperature (278–533 K), high pressure (6.9–276 MPa) density rather than fitting the models to low pressure saturated liquid density data. This high-temperature, high-pressure (HTHP) data base consists of literature data for hydrocarbons ranging from methane to C{sub 40}. The three new models developed in this work, HTHP VT-PR EoS, HTHP VT-SRK EoS, and hybrid PC-SAFT, yield mean absolute percent deviation values (MAPD) for HTHP hydrocarbon density of ~2.0%, ~1.5%, and <1.0%, respectively. An effort was also made to provide accurate hydrocarbon viscosity models based on literature data. Viscosity values are estimated with the frictional theory (f-theory) and free volume (FV) theory of viscosity. The best results were obtained when the PC-SAFT equation was used to obtain both the attractive and repulsive pressure inputs to f-theory, and the density input to FV theory. Both viscosity models provide accurate results at pressures to 100 MPa but experimental and model results can deviate by more than 25% at pressures above 200 MPa.

  17. Attentional load modulates responses of human primary visual cortex to invisible stimuli.

    Science.gov (United States)

    Bahrami, Bahador; Lavie, Nilli; Rees, Geraint

    2007-03-20

    Visual neuroscience has long sought to determine the extent to which stimulus-evoked activity in visual cortex depends on attention and awareness. Some influential theories of consciousness maintain that the allocation of attention is restricted to conscious representations [1, 2]. However, in the load theory of attention [3], competition between task-relevant and task-irrelevant stimuli for limited-capacity attention does not depend on conscious perception of the irrelevant stimuli. The critical test is whether the level of attentional load in a relevant task would determine unconscious neural processing of invisible stimuli. Human participants were scanned with high-field fMRI while they performed a foveal task of low or high attentional load. Irrelevant, invisible monocular stimuli were simultaneously presented peripherally and were continuously suppressed by a flashing mask in the other eye [4]. Attentional load in the foveal task strongly modulated retinotopic activity evoked in primary visual cortex (V1) by the invisible stimuli. Contrary to traditional views [1, 2, 5, 6], we found that availability of attentional capacity determines neural representations related to unconscious processing of continuously suppressed stimuli in human primary visual cortex. Spillover of attention to cortical representations of invisible stimuli (under low load) cannot be a sufficient condition for their awareness.

  18. How Attention Modulates Encoding of Dynamic Stimuli

    Science.gov (United States)

    Oren, Noga; Shapira-Lichter, Irit; Lerner, Yulia; Tarrasch, Ricardo; Hendler, Talma; Giladi, Nir; Ash, Elissa L.

    2016-01-01

    When encoding a real-life, continuous stimulus, the same neural circuits support processing and integration of prior as well as new incoming information. This ongoing interplay is modulated by attention, and is evident in regions such as the prefrontal cortex section of the task positive network (TPN), and in the posterior cingulate cortex (PCC), a hub of the default mode network (DMN). Yet the exact nature of such modulation is still unclear. To investigate this issue, we utilized an fMRI task that employed movies as the encoded stimuli and manipulated attentional load via an easy or hard secondary task that was performed simultaneously with encoding. Results showed increased intersubject correlation (inter-SC) levels when encoding movies in a condition of high, as compared to low attentional load. This was evident in bilateral ventrolateral and dorsomedial prefrontal cortices and the dorsal PCC (dPCC). These regions became more attuned to the combination of the movie and the secondary task as the attentional demand of the latter increased. Activation analyses revealed that at higher load the prefrontal TPN regions were more activated, whereas the dPCC was more deactivated. Attentional load also influenced connectivity within and between the networks. At high load the dPCC was anti-correlated to the prefrontal regions, which were more functionally coherent amongst themselves. Finally and critically, greater inter-SC in the dPCC at high load during encoding predicted lower memory strength when that information was retrieved. This association between inter-SC levels and memory strength suggest that as attentional demands increased, the dPCC was more attuned to the secondary task at the expense of the encoded stimulus, thus weakening memory for the encoded stimulus. Together, our findings show that attentional load modulated the function of core TPN and DMN regions. Furthermore, the observed relationship between memory strength and the modulation of the dPCC points

  19. Klinefelter syndrome has increased brain responses to auditory stimuli and motor output, but not to visual stimuli or Stroop adaptation.

    Science.gov (United States)

    Wallentin, Mikkel; Skakkebæk, Anne; Bojesen, Anders; Fedder, Jens; Laurberg, Peter; Østergaard, John R; Hertz, Jens Michael; Pedersen, Anders Degn; Gravholt, Claus Højbjerg

    2016-01-01

    Klinefelter syndrome (47, XXY) (KS) is a genetic syndrome characterized by the presence of an extra X chromosome and low level of testosterone, resulting in a number of neurocognitive abnormalities, yet little is known about brain function. This study investigated the fMRI-BOLD response from KS relative to a group of Controls to basic motor, perceptual, executive and adaptation tasks. Participants (N: KS = 49; Controls = 49) responded to whether the words "GREEN" or "RED" were displayed in green or red (incongruent versus congruent colors). One of the colors was presented three times as often as the other, making it possible to study both congruency and adaptation effects independently. Auditory stimuli saying "GREEN" or "RED" had the same distribution, making it possible to study effects of perceptual modality as well as Frequency effects across modalities. We found that KS had an increased response to motor output in primary motor cortex and an increased response to auditory stimuli in auditory cortices, but no difference in primary visual cortices. KS displayed a diminished response to written visual stimuli in secondary visual regions near the Visual Word Form Area, consistent with the widespread dyslexia in the group. No neural differences were found in inhibitory control (Stroop) or in adaptation to differences in stimulus frequencies. Across groups we found a strong positive correlation between age and BOLD response in the brain's motor network with no difference between groups. No effects of testosterone level or brain volume were found. In sum, the present findings suggest that auditory and motor systems in KS are selectively affected, perhaps as a compensatory strategy, and that this is not a systemic effect as it is not seen in the visual system.

  20. Klinefelter syndrome has increased brain responses to auditory stimuli and motor output, but not to visual stimuli or Stroop adaptation

    Directory of Open Access Journals (Sweden)

    Mikkel Wallentin

    2016-01-01

    Full Text Available Klinefelter syndrome (47, XXY (KS is a genetic syndrome characterized by the presence of an extra X chromosome and low level of testosterone, resulting in a number of neurocognitive abnormalities, yet little is known about brain function. This study investigated the fMRI-BOLD response from KS relative to a group of Controls to basic motor, perceptual, executive and adaptation tasks. Participants (N: KS = 49; Controls = 49 responded to whether the words “GREEN” or “RED” were displayed in green or red (incongruent versus congruent colors. One of the colors was presented three times as often as the other, making it possible to study both congruency and adaptation effects independently. Auditory stimuli saying “GREEN” or “RED” had the same distribution, making it possible to study effects of perceptual modality as well as Frequency effects across modalities. We found that KS had an increased response to motor output in primary motor cortex and an increased response to auditory stimuli in auditory cortices, but no difference in primary visual cortices. KS displayed a diminished response to written visual stimuli in secondary visual regions near the Visual Word Form Area, consistent with the widespread dyslexia in the group. No neural differences were found in inhibitory control (Stroop or in adaptation to differences in stimulus frequencies. Across groups we found a strong positive correlation between age and BOLD response in the brain's motor network with no difference between groups. No effects of testosterone level or brain volume were found. In sum, the present findings suggest that auditory and motor systems in KS are selectively affected, perhaps as a compensatory strategy, and that this is not a systemic effect as it is not seen in the visual system.

  1. The Influences of Static and Interactive Dynamic Facial Stimuli on Visual Strategies in Persons with Asperger Syndrome

    Science.gov (United States)

    Falkmer, Marita; Bjallmark, Anna; Larsson, Matilda; Falkmer, Torbjorn

    2011-01-01

    Several studies, using eye tracking methodology, suggest that different visual strategies in persons with autism spectrum conditions, compared with controls, are applied when viewing facial stimuli. Most eye tracking studies are, however, made in laboratory settings with either static (photos) or non-interactive dynamic stimuli, such as video…

  2. Klinefelter syndrome has increased brain responses to auditory stimuli and motor output, but not to visual stimuli or Stroop adaptation

    DEFF Research Database (Denmark)

    Wallentin, Mikkel; Skakkebæk, Anne; Bojesen, Anders

    2016-01-01

    Klinefelter syndrome (47, XXY) (KS) is a genetic syndrome characterized by the presence of an extra X chromosome and low level of testosterone, resulting in a number of neurocognitive abnormalities, yet little is known about brain function. This study investigated the fMRI-BOLD response from KS r....... No effects of testosterone level or brain volume were found. In sum, the present findings suggest that auditory and motor systems in KS are selectively affected, perhaps as a compensatory strategy, and that this is not a systemic effect as it is not seen in the visual system.......Klinefelter syndrome (47, XXY) (KS) is a genetic syndrome characterized by the presence of an extra X chromosome and low level of testosterone, resulting in a number of neurocognitive abnormalities, yet little is known about brain function. This study investigated the fMRI-BOLD response from KS...... response to motor output in primary motor cortex and an increased response to auditory stimuli in auditory cortices, but no difference in primary visual cortices. KS displayed a diminished response to written visual stimuli in secondary visual regions near the Visual Word Form Area, consistent...

  3. Go/no-go procedure with compound stimuli with children with autism.

    Science.gov (United States)

    Silva, Rafael Augusto; Debert, Paula

    2017-10-01

    The go/no-go with compound stimuli is an alternative to matching-to-sample to produce conditional and emergent relations in adults. The aim of this study was to evaluate the effectiveness of this procedure with two children diagnosed with autism. We trained and tested participants to respond to conditional relations among arbitrary stimuli using the go/no-go procedure. Both learned all the trained conditional relations without developing response bias or responding to no-go trials. Participants demonstrated performance consistent with symmetry, but not equivalence. © 2017 Society for the Experimental Analysis of Behavior.

  4. High intensity interval training vs. high-volume running training during pre-season conditioning in high-level youth football: a cross-over trial.

    Science.gov (United States)

    Faude, Oliver; Schnittker, Reinhard; Schulte-Zurhausen, Roman; Müller, Florian; Meyer, Tim

    2013-01-01

    We aimed at comparing the endurance effects of high-intensity interval training (HIIT) with high-volume running training (HVT) during pre-season conditioning in 20 high-level youth football players (15.9 (s 0.8) years). Players either conducted HVT or HIIT during the summer preparation period. During winter preparation they performed the other training programme. Before and after each training period several fitness tests were conducted: multi-stage running test (to assess the individual anaerobic threshold (IAT) and maximal running velocity (Vmax)), vertical jumping height, and straight sprinting. A significant increase from pre- to post-test was observed in IAT velocity (P velocity during the incremental exercise test also slightly increased with time (P = 0.09). Forty per cent (HIIT) and 15% (HVT) of all players did not improve IAT beyond baseline variability. The players who did not respond to HIIT were significantly slower during 30 m sprinting than responders (P = 0.02). No further significant differences between responders and non-responders were observed. Jump heights deteriorated significantly after both training periods (P football players during pre-season conditioning.

  5. Selective inattention to anxiety-linked stimuli.

    Science.gov (United States)

    Blum, G S; Barbour, J S

    1979-06-01

    The term selective inattention as used here subsumes those phenomena whose primary function is the active blocking or attenuation of partially processed contents en route to conscious expression. Examples are anxiety-motivated forgetting or perceptual distortion and hypnotically induced negative hallucinations. Studies in the field of selective attention have typically been designed to explain what takes place in a task in which the subject is first instructed to attend to a particular stimulus and then to consciously execute that instruction as well as he can. The rejection of content in process is examined only sceondarily as a consequence of the acceptance of relevant information. In the present experiments and theorizing, the emphasis instead is on inhibitory operations that take place automatically, without conscious intent, in response to a potential anxiety reaction. Experiment 1 explored the interaction of anxiety-linked inattention with strength of a target stimulus. Three female subjects were programmed under hypnosis to respond posthypnotically in the On condition with prescribed degrees of anxiety when certain Blacky pictures popped into mind later ,t the end of experimental trials; in the Off conditionall pictures were to become neutral. With the three female subjects still under hypnosis, each of the loaded pictures was then paired with a four-letter work relevant to the individual's own version of what was happening in the picture. The waking recognition task, carried out with amnesia for the prior hypnotic programming, consisted of tachistoscopic exposure of loaded words and physically similar filler words at four durations within a baseline range of recognition accuracy from 50%--75% correct. The data yielded a curvilinear relationship in which the recognition of only the loaded words was significnatly lower in the On condition at the 60%--70% range of recognition accuracy but not at shorter or longer stimulus durations. Experiment 2, for which the

  6. Blind Braille readers mislocate tactile stimuli.

    Science.gov (United States)

    Sterr, Annette; Green, Lisa; Elbert, Thomas

    2003-05-01

    In a previous experiment, we observed that blind Braille readers produce errors when asked to identify on which finger of one hand a light tactile stimulus had occurred. With the present study, we aimed to specify the characteristics of this perceptual error in blind and sighted participants. The experiment confirmed that blind Braille readers mislocalised tactile stimuli more often than sighted controls, and that the localisation errors occurred significantly more often at the right reading hand than at the non-reading hand. Most importantly, we discovered that the reading fingers showed the smallest error frequency, but the highest rate of stimulus attribution. The dissociation of perceiving and locating tactile stimuli in the blind suggests altered tactile information processing. Neuroplasticity, changes in tactile attention mechanisms as well as the idea that blind persons may employ different strategies for tactile exploration and object localisation are discussed as possible explanations for the results obtained.

  7. Discrimination of auditory stimuli during isoflurane anesthesia.

    Science.gov (United States)

    Rojas, Manuel J; Navas, Jinna A; Greene, Stephen A; Rector, David M

    2008-10-01

    Deep isoflurane anesthesia initiates a burst suppression pattern in which high-amplitude bursts are preceded by periods of nearly silent electroencephalogram. The burst suppression ratio (BSR) is the percentage of suppression (silent electroencephalogram) during the burst suppression pattern and is one parameter used to assess anesthesia depth. We investigated cortical burst activity in rats in response to different auditory stimuli presented during the burst suppression state. We noted a rapid appearance of bursts and a significant decrease in the BSR during stimulation. The BSR changes were distinctive for the different stimuli applied, and the BSR decreased significantly more when stimulated with a voice familiar to the rat as compared with an unfamiliar voice. These results show that the cortex can show differential sensory responses during deep isoflurane anesthesia.

  8. Photonic water dynamically responsive to external stimuli

    Science.gov (United States)

    Sano, Koki; Kim, Youn Soo; Ishida, Yasuhiro; Ebina, Yasuo; Sasaki, Takayoshi; Hikima, Takaaki; Aida, Takuzo

    2016-08-01

    Fluids that contain ordered nanostructures with periodic distances in the visible-wavelength range, anomalously exhibit structural colours that can be rapidly modulated by external stimuli. Indeed, some fish can dynamically change colour by modulating the periodic distance of crystalline guanine sheets cofacially oriented in their fluid cytoplasm. Here we report that a dilute aqueous colloidal dispersion of negatively charged titanate nanosheets exhibits structural colours. In this `photonic water', the nanosheets spontaneously adopt a cofacial geometry with an ultralong periodic distance of up to 675 nm due to a strong electrostatic repulsion. Consequently, the photonic water can even reflect near-infrared light up to 1,750 nm. The structural colour becomes more vivid in a magnetic flux that induces monodomain structural ordering of the colloidal dispersion. The reflective colour of the photonic water can be modulated over the entire visible region in response to appropriate physical or chemical stimuli.

  9. Preparation of stimuli for timbre perception studies.

    Science.gov (United States)

    Labuschagne, Ilse B; Hanekom, Johan J

    2013-09-01

    Stimuli used in timbre perception studies must be controlled carefully in order to yield meaningful results. During psychoacoustic testing of individual timbre properties, (1) it must be ensured that timbre properties do not co-vary, as timbre properties are often not independent from one another, and (2) the potential influence of loudness, pitch, and perceived duration must be eliminated. A mathematical additive synthesis method is proposed which allows complete control over two spectral parameters, the spectral centroid (corresponding to brightness) and irregularity, and two temporal parameters, log rise-time (LRT) and a parameter characterizing the sustain/decay segment, while controlling for covariation in the spectral centroid and irregularity. Thirteen musical instrument sounds were synthesized. Perceptual data from six listeners indicate that variation in the four timbre properties mainly influences loudness and that perceived duration and pitch are not influenced significantly for the stimuli of longer duration (2 s) used here. Trends across instruments were found to be similar.

  10. Physiological responses induced by pleasant stimuli.

    Science.gov (United States)

    Watanuki, Shigeki; Kim, Yeon-Kyu

    2005-01-01

    The specific physiological responses induced by pleasant stimuli were investigated in this study. Various physiological responses of the brain (encephaloelectrogram; EEG), autonomic nervous system (ANS), immune system and endocrine system were monitored when pleasant stimuli such as odors, emotional pictures and rakugo, a typical Japanese comical story-telling, were presented to subjects. The results revealed that (i) EEG activities of the left frontal brain region were enhanced by a pleasant odor; (ii) emotional pictures related to primitive element such as nudes and erotic couples elevated vasomotor sympathetic nervous activity; and (iii) an increase in secretory immunoglobulin A (s-IgA) and a decrease in salivary cortisol (s-cortisol) were induced by rakugo-derived linguistic pleasant emotion. Pleasant emotion is complicated state. However, by considering the evolutionary history of human being, it is possible to assess and evaluate pleasant emotion from certain physiological responses by appropriately summating various physiological parameters.

  11. Simulation of Stimuli-Responsive Polymer Networks

    Directory of Open Access Journals (Sweden)

    Thomas Gruhn

    2013-11-01

    Full Text Available The structure and material properties of polymer networks can depend sensitively on changes in the environment. There is a great deal of progress in the development of stimuli-responsive hydrogels for applications like sensors, self-repairing materials or actuators. Biocompatible, smart hydrogels can be used for applications, such as controlled drug delivery and release, or for artificial muscles. Numerical studies have been performed on different length scales and levels of details. Macroscopic theories that describe the network systems with the help of continuous fields are suited to study effects like the stimuli-induced deformation of hydrogels on large scales. In this article, we discuss various macroscopic approaches and describe, in more detail, our phase field model, which allows the calculation of the hydrogel dynamics with the help of a free energy that considers physical and chemical impacts. On a mesoscopic level, polymer systems can be modeled with the help of the self-consistent field theory, which includes the interactions, connectivity, and the entropy of the polymer chains, and does not depend on constitutive equations. We present our recent extension of the method that allows the study of the formation of nano domains in reversibly crosslinked block copolymer networks. Molecular simulations of polymer networks allow the investigation of the behavior of specific systems on a microscopic scale. As an example for microscopic modeling of stimuli sensitive polymer networks, we present our Monte Carlo simulations of a filament network system with crosslinkers.

  12. Anagrus breviphragma Soyka Short Distance Search Stimuli

    Directory of Open Access Journals (Sweden)

    Elisabetta Chiappini

    2015-01-01

    Full Text Available Anagrus breviphragma Soyka (Hymenoptera: Mymaridae successfully parasitises eggs of Cicadella viridis (L. (Homoptera: Cicadellidae, embedded in vegetal tissues, suggesting the idea of possible chemical and physical cues, revealing the eggs presence. In this research, three treatments were considered in order to establish which types of cue are involved: eggs extracted from leaf, used as a control, eggs extracted from leaf and cleaned in water and ethanol, used to evaluate the presence of chemicals soluble in polar solvents, and eggs extracted from leaf and covered with Parafilm (M, used to avoid physical stimuli due to the bump on the leaf surface. The results show that eggs covered with Parafilm present a higher number of parasitised eggs and a lower probing starting time with respect to eggs washed with polar solvents or eggs extracted and untreated, both when the treatments were singly tested or when offered in sequence, independently of the treatment position. These results suggest that the exploited stimuli are not physical due to the bump but chemicals that can spread in the Parafilm, circulating the signal on the whole surface, and that the stimuli that elicit probing and oviposition are not subjected to learning.

  13. Can prepared fear conditioning result from verbal instructions?

    NARCIS (Netherlands)

    Mertens, Gaëtan; Raes, An K.; De Houwer, Jan

    2016-01-01

    Evolutionary fear-relevant stimuli such as snakes or spiders are thought to be prepared to elicit fear reactions. This implies that the acquisition of conditioned fear responses is facilitated when these stimuli serve as conditioned stimuli (CSs). Moreover, extinction of conditioned fear responses i

  14. Data quality and practical challenges of thyroid volume assessment by ultrasound under field conditions - observer errors may affect prevalence estimates of goitre

    Directory of Open Access Journals (Sweden)

    Torheim Liv E

    2010-12-01

    Full Text Available Abstract Background The ultrasonographic estimation of thyroid size has been advocated as being more precise than palpation to diagnose goitre. However, ultrasound also requires technical proficiency. This study was conducted among Saharawi refugees, where goitre is highly prevalent. The objectives were to assess the overall data quality of ultrasound measurements of thyroid volume (Tvol, including the intra- and inter-observer agreement, under field conditions, and to describe some of the practical challenges encountered. Methods In 2007 a cross-sectional study of 419 children (6-14 years old and 405 women (15-45 years old was performed on a population of Saharawi refugees with prevalent goitre, who reside in the Algerian desert. Tvol was measured by two trained fieldworkers using portable ultrasound equipment (examiner 1 measured 406 individuals, and examiner 2, 418 individuals. Intra- and inter-observer agreement was estimated in 12 children selected from the study population but not part of the main study. In the main study, an observer error was found in one examiner whose ultrasound images were corrected by linear regression after printing and remeasuring a sample of 272 images. Results The intra-observer agreement in Tvol was higher in examiner 1, with an intraclass correlation coefficient (ICC of 0.97 (95% CI: 0.91, 0.99 compared to 0.86 (95% CI: 0.60, 0.96 in examiner 2. The ICC for inter-observer agreement in Tvol was 0.38 (95% CI: -0.20, 0.77. Linear regression coefficients indicated a significant scaling bias in the original measurements of the AP and ML diameter and a systematic underestimation of Tvol (a product of AP, ML, CC and a constant. The agreement between re-measured and original Tvol measured by ICC (95% CI was 0.76 (0.71, 0.81. The agreement between re-measured and corrected Tvol measured by ICC (95% CI was 0.97 (0.96, 0.97. Conclusions An important challenge when using ultrasound to assess thyroid volume under field

  15. FOR STIMULI-RESPONSIVE POLYMERS WITH ENHANCED EFFICIENCY IN RESERVOIR RECOVERY PROCESSES

    Energy Technology Data Exchange (ETDEWEB)

    Charles McCormick; Roger Hester

    2002-04-29

    To date, our synthetic research efforts have been focused on the development of stimuli-responsive water-soluble polymers designed for use in enhanced oil recovery (EOR) applications. These model systems are structurally tailored for potential application as viscosifiers and/or mobility control agents for secondary and tertiary EOR methods. The following report discloses the progress of our ongoing research of polyzwitterions, polymers derived from monomers bearing both positive and negative charges, that show the ability to sustain or increase their hydrodynamic volume (and thus, solution viscosity) in the presence of electrolytes. Such polymers appear to be well-suited for use under conditions similar to those encountered in EOR operations. Additionally, we disclose the synthesis and characterization of a well-defined set of polyacrylamide (PAM) homopolymers that vary by MW. The MW of the PAM samples is controlled by addition of sodium formate to the polymerization medium as a conventional chain transfer agent. Data derived from polymer characterization is used to determine the kinetic parameter C{sub CT}, the chain transfer constant to sodium formate under the given polymerization conditions. The PAM homopolymer series will be employed in future set of experiments designed to test a simplified intrinsic viscosity equation. The flow resistance of a polymer solution through a porous medium is controlled by the polymer's hydrodynamic volume, which is strongly related to it's intrinsic viscosity. However, the hydrodynamic volume of a polymer molecule in an aqueous solution varies with fluid temperature, solvent composition, and polymer structure. This report on the theory of polymer solubility accentuates the importance of developing polymer solutions that increase in intrinsic viscosity when fluid temperatures are elevated above room conditions. The intrinsic viscosity response to temperature and molecular weight variations of three polymer solutions

  16. Satellite cell activity, without expansion, after nonhypertrophic stimuli.

    Science.gov (United States)

    Joanisse, Sophie; McKay, Bryon R; Nederveen, Joshua P; Scribbans, Trisha D; Gurd, Brendon J; Gillen, Jenna B; Gibala, Martin J; Tarnopolsky, Mark; Parise, Gianni

    2015-11-01

    The purpose of the present studies was to determine the effect of various nonhypertrophic exercise stimuli on satellite cell (SC) pool activity in human skeletal muscle. Previously untrained men and women (men: 29 ± 9 yr and women: 29 ± 2 yr, n = 7 each) completed 6 wk of very low-volume high-intensity sprint interval training. In a separate study, recreationally active men (n = 16) and women (n = 3) completed 6 wk of either traditional moderate-intensity continuous exercise (n = 9, 21 ± 4 yr) or low-volume sprint interval training (n = 10, 21 ± 2 yr). Muscle biopsies were obtained from the vastus lateralis before and after training. The fiber type-specific SC response to training was determined, as was the activity of the SC pool using immunofluorescent microscopy of muscle cross sections. Training did not induce hypertrophy, as assessed by muscle cross-sectional area, nor did the SC pool expand in any group. However, there was an increase in the number of active SCs after each intervention. Specifically, the number of activated (Pax7(+)/MyoD(+), P ≤ 0.05) and differentiating (Pax7(-)/MyoD(+), P ≤ 0.05) SCs increased after each training intervention. Here, we report evidence of activated and cycling SCs that may or may not contribute to exercise-induced adaptations while the SC pool remains constant after three nonhypertrophic exercise training protocols.

  17. Sleep deprivation affects reactivity to positive but not negative stimuli.

    Science.gov (United States)

    Pilcher, June J; Callan, Christina; Posey, J Laura

    2015-12-01

    The current study examined the effects of partial and total sleep deprivation on emotional reactivity. Twenty-eight partially sleep-deprived participants and 31 totally sleep-deprived participants rated their valence and arousal responses to positive and negative pictures across four testing sessions during the day following partial sleep deprivation or during the night under total sleep deprivation. The results suggest that valence and arousal ratings decreased under both sleep deprivation conditions. In addition, partial and total sleep deprivation had a greater negative effect on positive events than negative events. These results suggest that sleep-deprived persons are more likely to respond less to positive events than negative events. One explanation for the current findings is that negative events could elicit more attentive behavior and thus stable responding under sleep deprivation conditions. As such, sleep deprivation could impact reactivity to emotional stimuli through automated attentional and self-regulatory processes. Copyright © 2015 Elsevier Inc. All rights reserved.

  18. From surface to volume plasmons in hyperbolic metamaterials: General existence conditions for bulk high-k waves in metal-dielectric and graphene-dielectric multilayers

    Science.gov (United States)

    Zhukovsky, Sergei V.; Andryieuski, Andrei; Sipe, J. E.; Lavrinenko, Andrei V.

    2014-10-01

    We theoretically investigate general existence conditions for broadband bulk large-wave-vector (high-k) propagating waves (such as volume plasmon polaritons in hyperbolic metamaterials) in subwavelength periodic multilayer structures. Describing the elementary excitation in the unit cell of the structure by a generalized resonance pole of a reflection coefficient and using Bloch's theorem, we derive analytical expressions for the band of large-wave-vector propagating solutions. We apply our formalism to determine the high-k band existence in two important cases: the well-known metal-dielectric and recently introduced graphene-dielectric stacks. We confirm that short-range surface plasmons in thin metal layers can give rise to hyperbolic metamaterial properties and demonstrate that long-range surface plasmons cannot. We also show that graphene-dielectric multilayers tend to support high-k waves and explore the range of parameteres for which this is possible, confirming the prospects of using graphene for materials with hyperbolic dispersion. The approach is applicable to a large variety of structures, such as continuous or structured microwave, terahertz, and optical metamaterials.

  19. Experimental and theoretical investigations in stimuli responsive dendrimer-based assemblies

    Science.gov (United States)

    Molla, Mijanur Rahaman; Rangadurai, Poornima; Pavan, Giovanni M.; Thayumanavan, S.

    2015-02-01

    Stimuli-responsive macromolecular assemblies are of great interest in drug delivery applications, as it holds the promise to keep the drug molecules sequestered under one set of conditions and release them under another. The former set of conditions could represent circulation, while the latter could represent a disease location. Over the past two decades, sizeable contributions to this field have come from dendrimers, which along with their monodispersity, provide great scope for structural modifications at the molecular level. In this paper, we briefly discuss the various synthetic strategies that have been developed so far to obtain a range of functional dendrimers. We then discuss the design strategies utilized to introduce stimuli responsive elements within the dendritic architecture. The stimuli itself are broadly classified into two categories, viz. extrinsic and intrinsic. Extrinsic stimuli are externally induced such as temperature and light variations, while intrinsic stimuli involve physiological aberrations such as variations in pH, redox conditions, proteins and enzyme concentrations in pathological tissues. Furthermore, the unique support from molecular dynamics (MD) simulations has been highlighted. MD simulations have helped back many of the observations made from assembly formation properties to rationalized the mechanism of drug release and this has been illustrated with discussions on G4 PPI (Poly propylene imine) dendrimers and biaryl facially amphiphilic dendrimers. The synergy that exists between experimental and theoretical studies open new avenues for the use of dendrimers as versatile drug delivery systems.

  20. Matching- and nonmatching-to-sample concept learning in rats using olfactory stimuli.

    Science.gov (United States)

    April, L Brooke; Bruce, Katherine; Galizio, Mark

    2011-09-01

    Previous research has shown that rats can learn matching-to-sample relations with olfactory stimuli; however, the specific characteristics of this relational control are unclear. In Experiment 1, 6 rats were trained to either match or nonmatch to sample in a modified operant chamber using common household spices as olfactory stimuli. After matching or nonmatching training with 10 exemplars, the contingencies were reversed with five new stimuli such that subjects trained on matching were shifted to nonmatching and vice versa. Following these reversed contingencies, the effects of the original training persisted for many trials with new exemplars. In Experiment 2, 9 rats were trained with matching procedures in an arena that provided for 18 different spatial locations for comparison stimuli. Five subjects were trained with differential reinforcement outcomes and 4 with only one type of reinforcer. Differential outcomes and multiple exemplars facilitated learning, and there was strong evidence for generalization to new stimuli for most rats that acquired several conditional discriminations. Performances with novel samples were generally above chance, but rarely reached the high levels obtained during baseline with well-trained stimulus relations. However, taken together, the data from the two experiments extend previous work, show that rats can learn both match and nonmatch relations with different experimental protocols, and demonstrate generalization to novel sample stimuli.

  1. Emotion attribution to basic parametric static and dynamic stimuli

    NARCIS (Netherlands)

    Visch, V.; Goudbeek, M.B.; Cohn, J.; Nijholt, A.; Pantic, P.

    2009-01-01

    The following research investigates the effect of basic visual stimuli on the attribution of basic emotions by the viewer. In an empirical study (N = 33) we used two groups of visually minimal expressive stimuli: dynamic and static. The dynamic stimuli consisted of an animated circle moving

  2. Emotion attribution to basic parametric static and dynamic stimuli

    NARCIS (Netherlands)

    Visch, V.; Goudbeek, M.B.; Cohn, J.; Nijholt, A.; Pantic, P.

    2009-01-01

    The following research investigates the effect of basic visual stimuli on the attribution of basic emotions by the viewer. In an empirical study (N = 33) we used two groups of visually minimal expressive stimuli: dynamic and static. The dynamic stimuli consisted of an animated circle moving accordin

  3. Hydrophilic-oleophobic stimuli-responsive materials and surfaces

    Science.gov (United States)

    Howarter, John A.

    Due to their high surface energy, hydrophilic surfaces are susceptible to contamination which is difficult to remove and often ruins the surface. Hydrophilic-oleophobic coatings have a diverse engineering potential including applications as self-cleaning surfaces, extended life anti-fog coatings, and environmental remediation in the selective filtration of oil-in-water mixtures. A successful design model for hydrophilic-oleophobic behavior has been developed using perfluorinated surfactants covalently bound to a surface. Within this design model, a variety of materials have been explored which the surfactants are covalently bound to a substrate; similarly, the surfactants may also be incorporated as a monomer into bulk copolymers. Surfactant based surfaces exhibited simultaneous hydrophilicity, necessary for anti-fogging, and oleophobicity, necessary for contamination resistance. The combination of these features rendered the surface as self-cleaning. Surfactant based brushes, composed of polyethylene glycol and perfluorinated constituents were grafted on to silica surfaces. The relationship between brush density and stimuli-responsiveness was determined by varying grafting conditions. The resultant surfaces were characterized with respect to chemical composition, brush thickness, and wetting behavior of water and hexadecane. Optimized surfaces exhibited stimuli-responsive behavior such that the surfaces will be wetted by water but not by oil. Surfactants were incorporated into random copolymers to create self-cleaning polymers which could be easily coated on to surfaces post-synthesis. Acrylic acid, methyl methacrylate, and hydroxyethyl methacrylate were used as comonomers; feed ratio was varied to establish compositional limits of stimuli-responsive behavior. Polymer composition dictated coating durability and self-cleaning performance as determined by water and hexadecane contact angle. The ability of select coatings to mitigate fogging was assessed in two

  4. Separating in vivo mechanical stimuli for postpneumonectomy compensation: physiological assessment.

    Science.gov (United States)

    Dane, D Merrill; Yilmaz, Cuneyt; Estrera, Aaron S; Hsia, Connie C W

    2013-01-01

    Following right pneumonectomy (PNX), the remaining lung expands and its perfusion doubles. Tissue and microvascular mechanical stresses are putative stimuli for initiating compensatory lung growth and remodeling, but their relative contributions to overall compensation remain uncertain. To temporally isolate the stimuli related to post-PNX lung expansion (parenchyma deformation) from those related to the sustained increase in perfusion (microvascular distention and shear), we replaced the right lung of adult dogs with a custom-shaped inflated prosthesis. Following stabilization of perfusion and wound healing 4 mo later, the prosthesis was either acutely deflated (DEF group) or kept inflated (INF group). Physiological studies were performed pre-PNX, 4 mo post-PNX (inflated prosthesis, INF1), and again 4 mo postdeflation (DEF) compared with controls with simultaneous INF prosthesis (INF2). Perfusion to the remaining lung increased ~76-113% post-PNX (INF1 and INF2) and did not change postdeflation. Post-PNX (INF prosthesis) end-expiratory lung volume (EELV) and lung and membrane diffusing capacities (DL(CO) and DM(CO)) at a given perfusion were 25-40% below pre-PNX baseline. In the INF group EELV, DL(CO) and DM(CO) remained stable or declined slightly with time. In contrast, all of these parameters increased significantly after deflation and were 157%, 26%, and 47%, respectively, above the corresponding control values (INF2). Following delayed deflation, lung expansion accounted for 44%-48% of total post-PNX compensatory increase in exercise DL(CO) and peak O(2) uptake; the remainder fraction is likely attributable to the increase in perfusion. Results suggest that expansion-related parenchyma mechanical stress and perfusion-related microvascular stress contribute in equal proportions to post-PNX alveolar growth and remodeling.

  5. Neural response to emotional stimuli during experimental human endotoxemia.

    Science.gov (United States)

    Kullmann, Jennifer S; Grigoleit, Jan-Sebastian; Lichte, Philipp; Kobbe, Philipp; Rosenberger, Christina; Banner, Christina; Wolf, Oliver T; Engler, Harald; Oberbeck, Reiner; Elsenbruch, Sigrid; Bingel, Ulrike; Forsting, Michael; Gizewski, Elke R; Schedlowski, Manfred

    2013-09-01

    Increases in peripheral cytokines during acute inflammation may affect various neuropsychological functions. The aim of this functional magnetic resonance imaging (fMRI) study was to investigate the effects of acute endotoxemia on mood and the neural response to emotionally aversive visual stimuli in healthy human subjects. In a double-blind, randomized crossover study, 18 healthy males received a bolus injection of bacterial lipopolysaccharide (LPS; 0.4 ng/kg) or saline. Plasma levels of pro- and anti-inflammatory cytokines and cortisol as well as mood ratings were analyzed together with the blood-oxygen-level dependent (BOLD) response during the presentation of aversive versus neutral pictures. Endotoxin administration induced pronounced transient increases in plasma levels of TNF-α, IL-1ra, IL-6, IL-10, and cortisol. Positive mood was decreased and state anxiety increased. In addition, activation of right inferior orbitofrontal cortex (OFC) in response to emotional visual stimuli was significantly increased in the LPS condition. Increased prefrontal activation during the presentation of emotional material may reflect enhanced cognitive regulation of emotions as an adaptive response during an acute inflammation. These findings may have implications for the putative role of inflammatory processes in the pathophysiology of depression.

  6. Task-irrelevant blindsight and the impact of invisible stimuli

    Directory of Open Access Journals (Sweden)

    Petra eStoerig

    2011-04-01

    Full Text Available Despite their subjective invisibility, stimuli presented within regions of absolute cortical blindness can both guide forced-choice behaviour when they are task-relevant and modulate responses to visible targets when they are task-irrelevant. We here tested three hemianopic patients to learn whether their performance in an attention-demanding rapid serial visual presentation task would be affected by task-irrelevant stimuli. Per trial, nine black letters and one white target-letter appeared briefly at fixation; the white letter was to be named at the end of each trial. On 50% of trials, a task-irrelevant disk (-.6 log contrast was presented to the blind field; in separate blocks, the same or a very low negative contrast distractor was presented to the sighted field. Mean error rates were high and independent of distractor condition, although the high contrast sighted-field disk impaired performance significantly in one participant. However, when trials with and without distractors were considered separately, performance was most impaired by the high contrast disk in the blind field, whereas the same disk in the sighted field had no effect. As this disk was least visible in the blind and most visible in the sighted field, attentional suppression was inversely related to visibility. We suggest that visual awareness, or the processes that generate it and are compromised in the blind hemisphere, enhances or enables effective attentional suppression.

  7. Task-irrelevant blindsight and the impact of invisible stimuli.

    Science.gov (United States)

    Stoerig, Petra

    2011-01-01

    Despite their subjective invisibility, stimuli presented within regions of absolute cortical blindness can both guide forced-choice behavior when they are task-relevant and modulate responses to visible targets when they are task-irrelevant. We here tested three hemianopic patients to learn whether their performance in an attention-demanding rapid serial visual presentation task would be affected by task-irrelevant stimuli. Per trial, nine black letters and one white target letter appeared briefly at fixation; the white letter was to be named at the end of each trial. On 50% of trials, a task-irrelevant disk (-0.6 log contrast) was presented to the blind field; in separate blocks, the same or a very low negative contrast distractor was presented to the sighted field. Mean error rates were high and independent of distractor condition, although the high-contrast sighted-field disk impaired performance significantly in one participant. However, when trials with and without distractors were considered separately, performance was most impaired by the high-contrast disk in the blind field, whereas the same disk in the sighted field had no effect. As this disk was least visible in the blind and most visible in the sighted field, attentional suppression was inversely related to visibility. We suggest that visual awareness, or the processes that generate it and are compromised in the blind hemisphere, enhances or enables effective attentional suppression.

  8. EEG Responses to Auditory Stimuli for Automatic Affect Recognition

    Science.gov (United States)

    Hettich, Dirk T.; Bolinger, Elaina; Matuz, Tamara; Birbaumer, Niels; Rosenstiel, Wolfgang; Spüler, Martin

    2016-01-01

    Brain state classification for communication and control has been well established in the area of brain-computer interfaces over the last decades. Recently, the passive and automatic extraction of additional information regarding the psychological state of users from neurophysiological signals has gained increased attention in the interdisciplinary field of affective computing. We investigated how well specific emotional reactions, induced by auditory stimuli, can be detected in EEG recordings. We introduce an auditory emotion induction paradigm based on the International Affective Digitized Sounds 2nd Edition (IADS-2) database also suitable for disabled individuals. Stimuli are grouped in three valence categories: unpleasant, neutral, and pleasant. Significant differences in time domain domain event-related potentials are found in the electroencephalogram (EEG) between unpleasant and neutral, as well as pleasant and neutral conditions over midline electrodes. Time domain data were classified in three binary classification problems using a linear support vector machine (SVM) classifier. We discuss three classification performance measures in the context of affective computing and outline some strategies for conducting and reporting affect classification studies. PMID:27375410

  9. Investigating the Predictive Value of Functional MRI to Appetitive and Aversive Stimuli: A Pattern Classification Approach

    Science.gov (United States)

    McCabe, Ciara; Rocha-Rego, Vanessa

    2016-01-01

    Background Dysfunctional neural responses to appetitive and aversive stimuli have been investigated as possible biomarkers for psychiatric disorders. However it is not clear to what degree these are separate processes across the brain or in fact overlapping systems. To help clarify this issue we used Gaussian process classifier (GPC) analysis to examine appetitive and aversive processing in the brain. Method 25 healthy controls underwent functional MRI whilst seeing pictures and receiving tastes of pleasant and unpleasant food. We applied GPCs to discriminate between the appetitive and aversive sights and tastes using functional activity patterns. Results The diagnostic accuracy of the GPC for the accuracy to discriminate appetitive taste from neutral condition was 86.5% (specificity = 81%, sensitivity = 92%, p = 0.001). If a participant experienced neutral taste stimuli the probability of correct classification was 92. The accuracy to discriminate aversive from neutral taste stimuli was 82.5% (specificity = 73%, sensitivity = 92%, p = 0.001) and appetitive from aversive taste stimuli was 73% (specificity = 77%, sensitivity = 69%, p = 0.001). In the sight modality, the accuracy to discriminate appetitive from neutral condition was 88.5% (specificity = 85%, sensitivity = 92%, p = 0.001), to discriminate aversive from neutral sight stimuli was 92% (specificity = 92%, sensitivity = 92%, p = 0.001), and to discriminate aversive from appetitive sight stimuli was 63.5% (specificity = 73%, sensitivity = 54%, p = 0.009). Conclusions Our results demonstrate the predictive value of neurofunctional data in discriminating emotional and neutral networks of activity in the healthy human brain. It would be of interest to use pattern recognition techniques and fMRI to examine network dysfunction in the processing of appetitive, aversive and neutral stimuli in psychiatric disorders. Especially where problems with reward and punishment processing have been implicated in the

  10. Discrimination of facial appearance stimuli in body dysmorphic disorder.

    Science.gov (United States)

    Stangier, Ulrich; Adam-Schwebe, Stefanie; Müller, Thomas; Wolter, Manfred

    2008-05-01

    Cognitive-behavioral models of body dysmorphic disorder (BDD) propose that information-processing biases--in particular, selective attention to a defect in one's appearance as well as improved aesthetical perception--might contribute to the development or maintenance of the disorder. In the present study, the authors tested the hypothesis that patients with BDD discriminate facial appearance stimuli more accurately than controls. Sixty female patients from a dermatological clinic participated in the study: 21 patients with BDD, 19 patients with disfiguring dermatological conditions, and 20 patients with nondisfiguring dermatological disorders. Participants rated dissimilarities between pictures of neutral faces that had been manipulated with regard to aesthetic characteristics. Manipulation ratings of participants with BDD were significantly more accurate than those of both control groups. Implications of these results for cognitive theories of BDD are discussed.

  11. Isolating the Incentive Salience of Reward-Associated Stimuli: Value, Choice, and Persistence

    Science.gov (United States)

    Beckmann, Joshua S.; Chow, Jonathan J.

    2015-01-01

    Sign- and goal-tracking are differentially associated with drug abuse-related behavior. Recently, it has been hypothesized that sign- and goal-tracking behavior are mediated by different neurobehavioral valuation systems, including differential incentive salience attribution. Herein, we used different conditioned stimuli to preferentially elicit…

  12. Modality and Task Switching Interactions using Bi-Modal and Bivalent Stimuli

    Science.gov (United States)

    Sandhu, Rajwant; Dyson, Benjamin J.

    2013-01-01

    Investigations of concurrent task and modality switching effects have to date been studied under conditions of uni-modal stimulus presentation. As such, it is difficult to directly compare resultant task and modality switching effects, as the stimuli afford both tasks on each trial, but only one modality. The current study investigated task and…

  13. Infant Attention to Dynamic Audiovisual Stimuli: Look Duration from 3 to 9 Months of Age

    Science.gov (United States)

    Reynolds, Greg D.; Zhang, Dantong; Guy, Maggie W.

    2013-01-01

    The goal of this study was to examine developmental change in visual attention to dynamic visual and audiovisual stimuli in 3-, 6-, and 9-month-old infants. Infant look duration was measured during exposure to dynamic geometric patterns and Sesame Street video clips under three different stimulus modality conditions: unimodal visual, synchronous…

  14. Termination of pinned spirals by local stimuli

    Science.gov (United States)

    Chen, Jiang-Xing; Guo, Ming-Ming; Ma, Jun

    2016-02-01

    The termination of pinned spirals on a defect by means of local stimuli is studied. On a completely unexcitable defect, the elimination process is discussed and its corresponding mechanism is presented. Especially, the mechanism of unpinning spirals on a partially unexcitable defect, which has not been investigated so far, is explored. With fixed pacing frequency ω L , there exists a maximal radius R max above which the pinned spiral cannot be removed. It is found that the value of R max does not increase as ω L in a dynamical regime, forming a platform in the R\\textit{max}\\text-ωL curves. Based on analyzing the dispersion relation on the spiral tip around the obstacle, the underlying mechanism is clarified. Also, it is found that when multiple spirals are pinned, the value of R max decreases on a partially unexcitable defect while the change is very slight on a completely unexcitable one.

  15. Working memory of emotional stimuli: Electrophysiological characterization.

    Science.gov (United States)

    Kessel, Dominique; García-Rubio, María J; González, E Kirstin; Tapia, Manuel; López-Martín, Sara; Román, Francisco J; Capilla, Almudena; Martínez, Kenia; Colom, Roberto; Carretié, Luis

    2016-09-01

    Memorizing emotional stimuli in a preferential way seems to be one of the adaptive strategies brought on by evolution for supporting survival. However, there is a lack of electrophysiological evidence on this bias in working memory. The present study analyzed the influence of emotion on the updating component of working memory. Behavioral and electrophysiological indices were measured from a 3-back task using negative, neutral, and positive faces. Electrophysiological data evidenced an emotional influence on the working memory sensitive P3 component, which presented larger amplitudes for negative matching faces compared to neutral ones. This effect originated in the superior parietal cortex, previously reported to be involved in N-back tasks. Additionally, P3 results showed a correlation with reaction times, where higher amplitudes were associated with faster responses for negative matching faces. These findings indicate that electrophysiological measures seem to be very suitable indices of the emotional influence on working memory.

  16. EEG Oscillation Evidences of Enhanced Susceptibility to Emotional Stimuli during Adolescence

    Science.gov (United States)

    Meng, Xianxin; Liu, Wenwen; Zhang, Ling; Li, Xiang; Yao, Bo; Ding, Xinsheng; Yuan, JiaJin; Yang, Jiemin

    2016-01-01

    Background: Our recent event-related potential (ERP) study showed that adolescents are more emotionally sensitive to negative events compared to adults, regardless of the valence strength of the events. The current work aimed to confirm this age-related difference in response to emotional stimuli of diverse intensities by examining Electroencephalography (EEG) oscillatory power in time-frequency analysis. Methods: Time-frequency analyses were performed on the EEG data recorded for highly negative (HN), moderately negative (MN) and Neutral pictures in 20 adolescents and 20 adults during a covert emotional task. The results showed a significant age by emotion interaction effect in the theta and beta oscillatory power during the 500–600 ms post stimulus. Results: Adolescents showed significantly less pronounced theta synchronization (ERS, 5.5–7.5 Hz) for HN stimuli, and larger beta desynchronization (ERD; 18–20 Hz) for both HN and MN stimuli, in comparison with neutral stimuli. By contrast, adults exhibited no significant emotion effects in theta and beta frequency bands. In addition, the analysis of the alpha spectral power (10.5–12 Hz; 850–950 ms) showed a main effect of emotion, while the emotion by age interaction was not significant. Irrespective of adolescents or adults, HN and MN stimuli elicited enhanced alpha suppression compared to Neutral stimuli, while the alpha power was similar across HN and MN conditions. Conclusions: These results confirmed prior findings that adolescents are more sensitive to emotionally negative stimuli compared to adults, regardless of emotion intensity, possibly due to the developing prefrontal control system during adolescence. PMID:27242568

  17. Conditional control of freezing by food deprivation intensity stimuli in Pavlovian conditioning procedures

    NARCIS (Netherlands)

    Maes, J.H.R.; Vossen, J.M.H.

    1996-01-01

    In Exp 1, rats were shocked in a training box under 1 level of food deprivation (FD) and not shocked under a different FD level. In Exp 2, rats received a single shock under 1 of 2 different FD levels. In Exp 3, rats were preexposed to a training box under 1 FD level and then received a single shock

  18. Event-related potentials in response to 3-D auditory stimuli.

    Science.gov (United States)

    Fuchigami, Tatsuo; Okubo, Osami; Fujita, Yukihiko; Kohira, Ryutaro; Arakawa, Chikako; Endo, Ayumi; Haruyama, Wakako; Imai, Yuki; Mugishima, Hideo

    2009-09-01

    To evaluate auditory spatial cognitive function, age correlations for event-related potentials (ERPs) in response to auditory stimuli with a Doppler effect were studied in normal children. A sound with a Doppler effect is perceived as a moving audio image. A total of 99 normal subjects (age range, 4-21 years) were tested. In the task-relevant oddball paradigm, P300 and key-press reaction time were elicited using auditory stimuli (1000 Hz fixed and enlarged tones with a Doppler effect). From the age of 4 years, the P300 latency for the enlarged tone with a Doppler effect shortened more rapidly with age than did the P300 latency for tone-pips, and the latencies for the different conditions became similar towards the late teens. The P300 of auditory stimuli with a Doppler effect may be used to evaluate auditory spatial cognitive function in children.

  19. Stimuli-Responsive Liposomes for Controlled Drug Delivery

    KAUST Repository

    Li, Wengang

    2014-09-01

    Liposomes are promising drug delivery vesicles due to their biodegradibility, large volume and biocompatibility towards both hydrophilic and hydrophobic drugs. They suffer, however, from poor stability which limits their use in controlled delivery applications. Herein, a novel method was devised for modification of liposomes with small molecules, polymers or nanoparticles to afford stimuli responsive systems that release on demand and stay relatively stable in the absence of the trigger.. This dissertation discusses thermosensitive, pH sensitive, light sensitive and magnetically triggered liposomes that have been prepared for controlled drug delivery application. RAFT polymerization was utilized for the preparation of thermosensitive liposomes (Cholesterol-PNIPAm) and acid-labile liposomes (DOPE-PAA). With low Mw Cholesterol-PNIPAm, the thermosensitive liposomes proved to be effective for controlled release and decreased the cytotoxicity of PNIPAm by eliciting the polymer doses. By crosslinking the DOPE-PAA on liposome surface with acid-labile diamine linkers, DOPE-PAA liposomes were verified to be sensitive at low pH. The effects of polymer structures (linear or hyperbranched) have also been studied for the stability and release properties of liposomes. Finally, a dual-responsive Au@SPIO embedded liposome hybrid (ALHs) was prepared with light-induced “on-and-off” function by photo-thermal process (visible light) and instant release properties triggered by alternating magnetic field, respectively. The ALH system would be further applied into the cellular imaging field as MRI contrast agent.

  20. Depersonalization disorder: disconnection of cognitive evaluation from autonomic responses to emotional stimuli.

    Directory of Open Access Journals (Sweden)

    Matthias Michal

    Full Text Available BACKGROUND: Patients with depersonalization disorder (DPD typically complain about emotional detachment. Previous studies found reduced autonomic responsiveness to emotional stimuli for DPD patients as compared to patients with anxiety disorders. We aimed to investigate autonomic responsiveness to emotional auditory stimuli of DPD patients as compared to patient controls. Furthermore, we examined the modulatory effect of mindful breathing on these responses as well as on depersonalization intensity. METHODS: 22 DPD patients and 15 patient controls balanced for severity of depression and anxiety, age, sex and education, were compared regarding 1 electrodermal and heart rate data during a resting period, and 2 autonomic responses and cognitive appraisal of standardized acoustic affective stimuli in two conditions (normal listening and mindful breathing. RESULTS: DPD patients rated the emotional sounds as significantly more neutral as compared to patient controls and standardized norm ratings. At the same time, however, they responded more strongly to acoustic emotional stimuli and their electrodermal response pattern was more modulated by valence and arousal as compared to patient controls. Mindful breathing reduced severity of depersonalization in DPD patients and increased the arousal modulation of electrodermal responses in the whole sample. Finally, DPD patients showed an increased electrodermal lability in the rest period as compared to patient controls. CONCLUSIONS: These findings demonstrated that the cognitive evaluation of emotional sounds in DPD patients is disconnected from their autonomic responses to those emotional stimuli. The increased electrodermal lability in DPD may reflect increased introversion and cognitive control of emotional impulses. The findings have important psychotherapeutic implications.

  1. Changes in Plasma Copeptin Levels during Hemodialysis: Are the Physiological Stimuli Active in Hemodialysis Patients?

    Directory of Open Access Journals (Sweden)

    Esmée M Ettema

    Full Text Available Plasma levels of copeptin, a surrogate marker for the vasoconstrictor hormone arginine vasopressin (AVP, are increased in hemodialysis patients. Presently, it is unknown what drives copeptin levels in hemodialysis patients. We investigated whether the established physiological stimuli for copeptin release, i.e. plasma osmolality, blood volume and mean arterial pressure (MAP, are operational in hemodialysis patients.One hundred and eight prevalent, stable hemodialysis patients on a thrice-weekly dialysis schedule were studied during hemodialysis with constant ultrafiltration rate and dialysate conductivity in this observational study. Plasma levels of copeptin, sodium, MAP, and blood volume were measured before, during and after hemodialysis. Multivariate analysis was used to determine the association between copeptin (dependent variable and the physiological stimuli plasma sodium, MAP, excess weight as well as NT-pro-BNP immediately prior to dialysis and between copeptin and changes of plasma sodium, MAP and blood volume with correction for age, sex and diabetes during dialysis treatment.Patients were 63 ± 15.6 years old and 65% were male. Median dialysis vintage was 1.6 years (IQR 0.7-4.0. Twenty-three percent of the patients had diabetes and 82% had hypertension. Median predialysis copeptin levels were 141.5 pmol/L (IQR 91.0-244.8 pmol/L. Neither predialysis plasma sodium levels, nor NT-proBNP levels, nor MAP were associated with predialysis copeptin levels. During hemodialysis, copeptin levels rose significantly (p<0.01 to 163.0 pmol/L (96.0-296.0 pmol/L. Decreases in blood volume and MAP were associated with increases in copeptin levels during dialysis, whereas there was no significant association between the change in plasma sodium levels and the change in copeptin levels.Plasma copeptin levels are elevated predialysis and increase further during hemodialysis. Volume stimuli, i.e. decreases in MAP and blood volume, rather than osmotic

  2. Text-mining network analysis of the response to osmotic stimuli in the intervertebral disc.

    Science.gov (United States)

    Xu, X; Liu, L; Lu, Q Y

    2013-05-13

    Intervertebral disc cells experience a broad range of physical stimuli under physiologic conditions, including alterations in their osmotic environment. The purpose of this study was to construct a text-mining network of the genes induced during the response to osmotic stimuli in the intervertebral disc. We obtained a gene expression profile of human intervertebral disc cells from the National Center for Biotechnology Information, after culture under hyper- and hypo-osmotic conditions compared to iso-osmotic conditions, and we identified 65 differentially expressed genes of intervertebral disc cells. We constructed a text-mining network using Biblio-MetReS between the differentially expressed genes and other genes that were included in the same document as the differentially expressed genes. Then, we performed pathway-enrichment analysis to identify the most relevant pathways for the response to osmotic stimuli in intervertebral disc cells. Our data provide a comprehensive bioinformatics analysis of genes and pathways that may be involved in the response to osmotic stimuli in the intervertebral disc.

  3. Early Pavlovian conditioning impairs later Pavlovian conditioning.

    Science.gov (United States)

    Lariviere, N A; Spear, N E

    1996-11-01

    Four experiments tested the effects in the rat of very early experience with stimuli to be used later for Pavlovian conditioning. Beginning on postnatal Day 12, prior to the development of substantial detection and effective perception of visual and auditory stimuli, rats were given five daily experiences with either lights or tones and a footshock known to be an effective unconditioned stimulus at these ages. Twenty-four hours after the last of these experiences, pairings of either the light or tone and the unconditioned stimulus were given with parameters established to yield a moderate degree of conditioning in untreated preweanlings (Experiment 1). Experiment 2 determined that early experience with paired or unpaired presentations of either the light or tone and the unconditioned stimulus resulted in a failure to condition to these same lights or tones on postnatal Day 17, although nontreated pups from the same litters conditioned quite effectively. Experiment 3 determined that this early conditioning experience with either paired or unpaired presentations of the lights or tones and the unconditioned stimulus yielded impaired conditioning on postnatal Day 17 in the alternative sensory modality as well, although again nontreated siblings conditioned quite effectively. Experiment 4 replicated the results of each of Experiments 2 and 3 and determined in addition that despite the impairment in conditioning that resulted from early paired or unpaired experience with the stimuli of conditioning, early experience with the individual stimuli of conditioning-with only the CS, the US, or the context-did not result in a similar impairment in conditioning. Although the results were unexpected, they may be understood in part in terms of intersensory competition during development, and there is precedent in the literature for similar interfering effects of early learning on later learning in a variety of species.

  4. The neural response to maternal stimuli: an ERP study.

    Science.gov (United States)

    Wu, Lili; Gu, Ruolei; Cai, Huajian; Luo, Yu L L; Zhang, Jianxin

    2014-01-01

    Mothers are important to all humans. Research has established that maternal information affects individuals' cognition, emotion, and behavior. We measured event-related potentials (ERPs) to examine attentional and evaluative processing of maternal stimuli while participants completed a Go/No-go Association Task that paired mother or others words with good or bad evaluative words. Behavioral data showed that participants responded faster to mother words paired with good than the mother words paired with bad but showed no difference in response to these others across conditions, reflecting a positive evaluation of mother. ERPs showed larger P200 and N200 in response to mother than in response to others, suggesting that mother attracted more attention than others. In the subsequent time window, mother in the mother + bad condition elicited a later and larger late positive potential (LPP) than it did in the mother + good condition, but this was not true for others, also suggesting a positive evaluation of mother. These results suggest that people differentiate mother from others during initial attentional stage, and evaluative mother positively during later stage.

  5. Valuation of Go Stimuli or Devaluation of No-Go Stimuli? Evidence of an Increased Preference for Attended Go Stimuli Following a Go/No-Go Task.

    Science.gov (United States)

    Inoue, Kazuya; Sato, Nobuya

    2017-01-01

    Attentional inhibition that occurs during discrimination tasks leads to the negative evaluation of distractor stimuli. This phenomenon, known as the distractor devaluation effect also occurs when go/no-go tasks require response inhibition. However, it remains unclear whether there are interactions between attention and response controls when the distractor devaluation effect occurs. The aims of this study were to investigate whether attention to stimuli in the go/no-go task plays a facilitative role in distractor devaluation through response inhibition, and to clarify whether this effect reflects a decreased preference for no-go stimuli. Participants evaluated the preference for pictures before and after a go/no-go task. In Experiments 1 and 2, they made a go or no-go response depending on the category of pictures displayed (gummy candies or rice crackers), whereas in Experiment 3 they did on the basis digit category, even or odd numbers, superimposed on such pictures. Experiments 1 and 2 demonstrated that the pictures presented as no-go stimuli in the preceding go/no-go task were evaluated as less positive than the pictures presented as go stimuli. This devaluation effect reflected an increased preference for the go stimuli but not a decreased preference for the no-go stimuli. Experiment 3 indicated that response inhibition did not affect the preference for the pictures that had not received attention in a preceding go/no-go task. These results suggest that although attention plays an important role in differential ratings for go and no-go stimuli, such differences, in fact, reflect the valuation of go stimuli.

  6. 发酵条件与面团体积、面包品质关系的研究%Effects of Fermentation Condition on the Dough Volume and Bread Quality

    Institute of Scientific and Technical Information of China (English)

    豆康宁; 李超敏; 尹军杰

    2012-01-01

    The fermentation condition determines the dough volume,and the dough volume is the main factor affecting the quality of bread.So the quality of bread could be controlled through fermentation conditions.The experiment results showed that the optimal fermentation conditions are temperature 35 ℃,time 1.5 h.The dough volume increased to 3 times of the original,and the bread quality will be the best under this condition.%发酵条件决定面团的体积,而面团体积是影响面包品质的主要因素。通过研究发酵条件对面包面团体积的影响,从而控制面团体积对面包品质的影响。试验结果表明,面团最佳发酵条件温度为35℃,时间为1.5h,在此条件下面团体积增加为原来的3倍,面包品质最好。

  7. Reduced Interocular Transfer of Spatial Adaptation for Fast Stimuli

    Directory of Open Access Journals (Sweden)

    Daniel H Baker

    2012-05-01

    Full Text Available Threshold elevation following monocular adaptation is weaker in the unadapted eye than in the adapted eye. At least 15 studies have measured this interocular transfer (IOT phenomenon, and typically report around 60% transfer. Yet almost all of these studies used spatial frequencies above 3c/deg, very slow temporal parameters, and criterion sensitive methods (method of adjustment, yes/no. In recent work, we (Meese and Baker 2011, i-Perception 2 159–182 found markedly weaker interocular transfer at low spatial and high temporal frequencies. Here, we measure IOT in 9 observers for a broad range of spatiotemporal frequencies (0.5, 2, and 8c/deg; 1, 4, and 15Hz using a 2AFC paradigm. Targets were horizontal Gabor patches with a full-width-at-half height of 1.67 (lower frequencies or 6.68 (8c/deg grating cycles. Adaptors were larger gratings with the same spatiotemporal properties as the targets. Observers adapted for 2 min initially, and 5 s between each trial, with monocular presentation enabled by shutter goggles. We typically found weaker IOT than previously reported (<50%, particularly for our fastest stimuli (lowest spatial and highest temporal frequencies, where it was virtually absent in all cases. Binocular summation and monocular adaptation were normal in all conditions. This implies that adaptation to ‘magno’ stimuli, not investigated in previous studies, occurs at a monocular locus. We also consider possible methodological confounds in classical studies which might have inflated the levels of IOT. These include the formation of retinal afterimages from static adaptors and changes in criterion unrelated to changes in sensitivity.

  8. Gender differences in associations of sexual and romantic stimuli: do young men really prefer sex over romance?

    Science.gov (United States)

    Thompson, Ashley E; O'Sullivan, Lucia F

    2012-08-01

    Theory and research emphasize differences in men's and women's sexual and romantic attitudes, concluding that men have stronger preferences for sexual than romantic stimuli as compared to women. However, most of the research on gender differences have relied on self-reports, which are plagued by problems of social desirability bias. The current study assessed young men's and women's implicit attitudes toward sexual and romantic stimuli to test whether, in fact, men have a stronger preference for sexual over romantic stimuli compared to women. We also assessed associations between implicit and explicit attitudes, as well as sex role ideology and personality. College students (68 men and 114 women) completed an Implicit Association Test (IAT) that assessed strengths of associations of sexual and romantic stimuli to both pleasant and unpleasant conditions. Results revealed that both men and women more strongly associated romantic images to the pleasant condition than they associated the sexual images to the pleasant condition. However, as predicted, women had a stronger preference toward romantic versus sexual stimuli compared to men. Our study challenges a common assumption that men prefer sexual over romantic stimuli. The findings indicate that measures of implicit attitudes may tap preferences that are not apparent in studies relying on self-reported (explicit) attitudes.

  9. Happiness increases distraction by auditory deviant stimuli.

    Science.gov (United States)

    Pacheco-Unguetti, Antonia Pilar; Parmentier, Fabrice B R

    2016-08-01

    Rare and unexpected changes (deviants) in an otherwise repeated stream of task-irrelevant auditory distractors (standards) capture attention and impair behavioural performance in an ongoing visual task. Recent evidence indicates that this effect is increased by sadness in a task involving neutral stimuli. We tested the hypothesis that such effect may not be limited to negative emotions but reflect a general depletion of attentional resources by examining whether a positive emotion (happiness) would increase deviance distraction too. Prior to performing an auditory-visual oddball task, happiness or a neutral mood was induced in participants by means of the exposure to music and the recollection of an autobiographical event. Results from the oddball task showed significantly larger deviance distraction following the induction of happiness. Interestingly, the small amount of distraction typically observed on the standard trial following a deviant trial (post-deviance distraction) was not increased by happiness. We speculate that happiness might interfere with the disengagement of attention from the deviant sound back towards the target stimulus (through the depletion of cognitive resources and/or mind wandering) but help subsequent cognitive control to recover from distraction. © 2015 The British Psychological Society.

  10. Psychophysiological response patterns to affective film stimuli.

    Directory of Open Access Journals (Sweden)

    Marieke G N Bos

    Full Text Available Psychophysiological research on emotion utilizes various physiological response measures to index activation of the defense system. Here we tested 1 whether acoustic startle reflex (ASR, skin conductance response (SCR and heart rate (HR elicited by highly arousing stimuli specifically reflect a defensive state and 2 the relation between resting heart rate variability (HRV and affective responding. In a within-subject design, participants viewed film clips with a positive, negative and neutral content. In contrast to SCR and HR, we show that ASR differentiated between negative, neutral and positive states and can therefore be considered as a reliable index of activation of the defense system. Furthermore, resting HRV was associated with affect-modulated characteristics of ASR, but not with SCR or HR. Interestingly, individuals with low-HRV showed less differentiation in ASR between affective states. We discuss the important value of ASR in psychophysiological research on emotion and speculate on HRV as a potential biological marker for demarcating adaptive from maladaptive responding.

  11. Anchoring in Numeric Judgments of Visual Stimuli.

    Science.gov (United States)

    Langeborg, Linda; Eriksson, Mårten

    2016-01-01

    This article investigates effects of anchoring in age estimation and estimation of quantities, two tasks which to different extents are based on visual stimuli. The results are compared to anchoring in answers to classic general knowledge questions that rely on semantic knowledge. Cognitive load was manipulated to explore possible differences between domains. Effects of source credibility, manipulated by differing instructions regarding the selection of anchor values (no information regarding anchor selection, information that the anchors are randomly generated or information that the anchors are answers from an expert) on anchoring were also investigated. Effects of anchoring were large for all types of judgments but were not affected by cognitive load or by source credibility in either one of the researched domains. A main effect of cognitive load on quantity estimations and main effects of source credibility in the two visually based domains indicate that the manipulations were efficient. Implications for theoretical explanations of anchoring are discussed. In particular, because anchoring did not interact with cognitive load, the results imply that the process behind anchoring in visual tasks is predominantly automatic and unconscious.

  12. Processing of voiced and unvoiced acoustic stimuli in musicians

    Directory of Open Access Journals (Sweden)

    Cyrill Guy Martin Ott

    2011-09-01

    Full Text Available Past research has shown that musical training induces changes in the processing of supra-segmental aspects of speech, such as pitch and prosody. The aim of the present study was to determine whether musical expertise also leads to an altered neurophysiological processing of sub-segmental information available in the speech signal, in particular the voice onset time (VOT. Using high-density EEG recordings we analysed the neurophysiological responses to voiced and unvoiced CV syllables and noise analogues in 26 German speaking adult musicians and non-musicians. From the EEG the N1 amplitude of the event-related potential (ERP and two microstates from the topographical EEG analysis (one around the N1 amplitude and one immediately preceding the N1 microstate were calculated to the different stimuli. Similar to earlier studies the N1 amplitude was different to voiced and unvoiced stimuli in non-musicians with larger amplitudes to voiced stimuli. The more refined microstate analysis revealed that the microstate within the N1 time window was shorter to unvoiced stimuli in non-musicians. For musicians there was no difference for the N1 amplitudes and the corresponding microstates between voiced and unvoiced stimuli. In addition, there was a longer very early microstate preceding the microstate at the N1 time window to non-speech stimuli only in musicians. Taken together, our findings suggest that musicians process unvoiced stimuli (irrespective whether these stimuli are speech or non-speech stimuli differently. We propose that musicians utilise the same network to analyse unvoiced stimuli as for the analysis of voiced stimuli. As a further explanation it is also possible that musicians devote more neurophysiological resources into the analysis of unvoiced segments.

  13. Posturographic destabilization in eating disorders in female patients exposed to body image related phobic stimuli.

    Science.gov (United States)

    Forghieri, M; Monzani, D; Mackinnon, A; Ferrari, S; Gherpelli, C; Galeazzi, G M

    2016-08-26

    Human postural control is dependent on the central integration of vestibular, visual and proprioceptive inputs. Psychological states can affect balance control: anxiety, in particular, has been shown to influence balance mediated by visual stimuli. We hypothesized that patients with eating disorders would show postural destabilization when exposed to their image in a mirror and to the image of a fashion model representing their body ideal in comparison to body neutral stimuli. Seventeen females patients attending a day centre for the treatment of eating disorders were administered psychometric measures of body dissatisfaction, anxiety, depression and underwent posturographic measures with their eyes closed, open, watching a neutral stimulus, while exposed to a full length mirror and to an image of a fashion model corresponding to their body image. Results were compared to those obtained by eighteen healthy subjects. Eating disordered patients showed higher levels of body dissatisfaction and higher postural destabilization than controls, but this was limited to the conditions in which they were exposed to their mirror image or a fashion model image. Postural destabilization under these conditions correlated with measures of body dissatisfaction. In eating disordered patients, body related stimuli seem to act as phobic stimuli in the posturographic paradigm used. If confirmed, this has the potential to be developed for diagnostic and therapeutic purposes. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  14. Post-Decision Wagering Affects Metacognitive Awareness of Emotional Stimuli: An Event Related Potential Study.

    Science.gov (United States)

    Wierzchoń, Michał; Wronka, Eligiusz; Paulewicz, Borysław; Szczepanowski, Remigiusz

    2016-01-01

    The present research investigated metacognitive awareness of emotional stimuli and its psychophysiological correlates. We used a backward masking task presenting participants with fearful or neutral faces. We asked participants for face discrimination and then probed their metacognitive awareness with confidence rating (CR) and post-decision wagering (PDW) scales. We also analysed psychophysiological correlates of awareness with event-related potential (ERP) components: P1, N170, early posterior negativity (EPN), and P3. We have not observed any differences between PDW and CR conditions in the emotion identification task. However, the "aware" ratings were associated with increased accuracy performance. This effect was more pronounced in PDW, especially for fearful faces, suggesting that emotional stimuli awareness may be enhanced by monetary incentives. EEG analysis showed larger N170, EPN and P3 amplitudes in aware compared to unaware trials. It also appeared that both EPN and P3 ERP components were more pronounced in the PDW condition, especially when emotional faces were presented. Taken together, our ERP findings suggest that metacognitive awareness of emotional stimuli depends on the effectiveness of both early and late visual information processing. Our study also indicates that awareness of emotional stimuli can be enhanced by the motivation induced by wagering.

  15. How Does Temporal Frequency Affect Impression Formation for Audio-Visual Stimuli?

    Directory of Open Access Journals (Sweden)

    Miharu Yamada

    2011-10-01

    Full Text Available In this study, we examined the effects of the temporal frequency of the audio–visual stimuli on the impression formation and perception of the temporal congruency. In our previous study (2010 with two temporal frequency conditions (108, and 216bpm, we found that both the processing which underlies the impression formation of the temporal congruency and the processing which underlies the perceptual judgment depend not only upon the time lag between the audio and visual stimuli but also upon the temporal frequency of the stimuli. As visual stimulus, we used repetitive luminance change of the computer graphic image with a constant temporal frequency (87, 108, 146, or 216bpm. As audio stimulus, we used periodic drum sounds consisting of a low tam and three cymbals. There were nine conditions for asynchrony between the visual and audio stimuli (±0, 96, 192, 288, and 384ms. We found that the range of the audio-visual asynchrony for the temporal congruent impression is much narrower than the range for the temporal congruent perception. These results suggest that the perception of the temporal congruency does not determine the impression formation for the temporal congruency.

  16. Augmenting one-session treatment of children's specific phobias with attention training to positive stimuli.

    Science.gov (United States)

    Waters, Allison M; Farrell, Lara J; Zimmer-Gembeck, Melanie J; Milliner, Ella; Tiralongo, Evelin; Donovan, Caroline L; McConnell, Harry; Bradley, Brendan P; Mogg, Karin; Ollendick, Thomas H

    2014-11-01

    This study examined the efficacy of combining two promising approaches to treating children's specific phobias, namely attention training and one 3-h session of exposure therapy ('one-session treatment', OST). Attention training towards positive stimuli (ATP) and OST (ATP+OST) was expected to have more positive effects on implicit and explicit cognitive mechanisms and clinical outcome measures than an attention training control (ATC) condition plus OST (ATC+OST). Thirty-seven children (6-17 years) with a specific phobia were randomly assigned to ATP+OST or ATC+OST. In ATP+OST, children completed 160 trials of attention training responding to a probe that always followed the happy face in happy-angry face pairs. In ATC+OST, the probe appeared equally often after angry and happy faces. In the same session, children completed OST targeting their phobic situation/object. Clinical outcomes included clinician, parent and child report measures. Cognitive outcomes were assessed in terms of change in attention bias to happy and angry faces and in danger and coping expectancies. Assessments were completed before and after treatment and three-months later. Compared to ATC+OST, the ATP+OST condition produced (a) significantly greater reductions in children's danger expectancies about their feared situations/object during the OST and at three-month follow-up, and (b) significantly improved attention bias towards positive stimuli at post-treatment, which in turn, predicted a lower level of clinician-rated phobia diagnostic severity three-months after treatment. There were no significant differences between ATP+OST and ATC+OST conditions in clinician, parent, or child-rated clinical outcomes. Training children with phobias to focus on positive stimuli is effective in increasing attention towards positive stimuli and reducing danger expectancy biases. Studies with larger sample sizes and a stronger 'dose' of ATP prior to the OST may reveal promising outcomes on clinical measures

  17. Is silence golden? Effects of auditory stimuli and their absence on adult hippocampal neurogenesis.

    Science.gov (United States)

    Kirste, Imke; Nicola, Zeina; Kronenberg, Golo; Walker, Tara L; Liu, Robert C; Kempermann, Gerd

    2015-03-01

    We have previously hypothesized that the reason why physical activity increases precursor cell proliferation in adult neurogenesis is that movement serves as non-specific signal to evoke the alertness required to meet cognitive demands. Thereby a pool of immature neurons is generated that are potentially recruitable by subsequent cognitive stimuli. Along these lines, we here tested whether auditory stimuli might exert a similar non-specific effect on adult neurogenesis in mice. We used the standard noise level in the animal facility as baseline and compared this condition to white noise, pup calls, and silence. In addition, as patterned auditory stimulus without ethological relevance to mice we used piano music by Mozart (KV 448). All stimuli were transposed to the frequency range of C57BL/6 and hearing was objectified with acoustic evoked potentials. We found that except for white noise all stimuli, including silence, increased precursor cell proliferation (assessed 24 h after labeling with bromodeoxyuridine, BrdU). This could be explained by significant increases in BrdU-labeled Sox2-positive cells (type-1/2a). But after 7 days, only silence remained associated with increased numbers of BrdU-labeled cells. Compared to controls at this stage, exposure to silence had generated significantly increased numbers of BrdU/NeuN-labeled neurons. Our results indicate that the unnatural absence of auditory input as well as spectrotemporally rich albeit ethological irrelevant stimuli activate precursor cells-in the case of silence also leading to greater numbers of newborn immature neurons-whereas ambient and unstructured background auditory stimuli do not.

  18. Characterization of functional biopolymers under various external stimuli

    Energy Technology Data Exchange (ETDEWEB)

    Maleki, Atoosa

    2008-07-01

    Polymers are large molecules composed of repeating structural units connected by covalent chemical bonds. Biopolymers are a class of polymers produced by living organisms, which exhibit both biocompatible and biodegradable properties. The behavior of a biopolymer in solution is strongly dependent on the chemical and physical structure of the polymer chain, as well as external environmental conditions. To improve biopolymers in the direction of higher performance and better functionality, understanding of their physicochemical behavior and their response to external stimuli are of great importance. Rheology, rheo-small angle light scattering, dynamic light scattering, small angle neutron scattering, and asymmetric flow field-flow fractionation were utilized in this thesis to investigate the properties of hydroxyethyl cellulose and its hydrophobically modified analogue, as well as dextran, hyaluronan, and mucin under different conditions such as temperature, solvent, mechanical stress and strain, and radiation. Different novel hydrogels were prepared by using various chemical cross-linking agents. Specific features of these macromolecules provide them to be used as 'functional' materials, e.g., sensors, actuators, personal care products, enhanced oil recovery, and controlled drug delivery systems (author)

  19. Logical Rules and the Classification of Integral-Dimension Stimuli

    Science.gov (United States)

    Little, Daniel R.; Nosofsky, Robert M.; Donkin, Christopher; Denton, Stephen E.

    2013-01-01

    A classic distinction in perceptual information processing is whether stimuli are composed of separable dimensions, which are highly analyzable, or integral dimensions, which are processed holistically. Previous tests of a set of logical-rule models of classification have shown that separable-dimension stimuli are processed serially if the…

  20. Inverse Target- and Cue-Priming Effects of Masked Stimuli

    Science.gov (United States)

    Mattler, Uwe

    2007-01-01

    The processing of a visual target that follows a briefly presented prime stimulus can be facilitated if prime and target stimuli are similar. In contrast to these positive priming effects, inverse priming effects (or negative compatibility effects) have been found when a mask follows prime stimuli before the target stimulus is presented: Responses…

  1. Exploring Visuomotor Priming Following Biological and Non-Biological Stimuli

    Science.gov (United States)

    Gowen, E.; Bradshaw, C.; Galpin, A.; Lawrence, A.; Poliakoff, E.

    2010-01-01

    Observation of human actions influences the observer's own motor system, termed visuomotor priming, and is believed to be caused by automatic activation of mirror neurons. Evidence suggests that priming effects are larger for biological (human) as opposed to non-biological (object) stimuli and enhanced when viewing stimuli in mirror compared to…

  2. Exploring Visuomotor Priming Following Biological and Non-Biological Stimuli

    Science.gov (United States)

    Gowen, E.; Bradshaw, C.; Galpin, A.; Lawrence, A.; Poliakoff, E.

    2010-01-01

    Observation of human actions influences the observer's own motor system, termed visuomotor priming, and is believed to be caused by automatic activation of mirror neurons. Evidence suggests that priming effects are larger for biological (human) as opposed to non-biological (object) stimuli and enhanced when viewing stimuli in mirror compared to…

  3. Gender differences in identifying emotions from auditory and visual stimuli.

    Science.gov (United States)

    Waaramaa, Teija

    2017-12-01

    The present study focused on gender differences in emotion identification from auditory and visual stimuli produced by two male and two female actors. Differences in emotion identification from nonsense samples, language samples and prolonged vowels were investigated. It was also studied whether auditory stimuli can convey the emotional content of speech without visual stimuli, and whether visual stimuli can convey the emotional content of speech without auditory stimuli. The aim was to get a better knowledge of vocal attributes and a more holistic understanding of the nonverbal communication of emotion. Females tended to be more accurate in emotion identification than males. Voice quality parameters played a role in emotion identification in both genders. The emotional content of the samples was best conveyed by nonsense sentences, better than by prolonged vowels or shared native language of the speakers and participants. Thus, vocal non-verbal communication tends to affect the interpretation of emotion even in the absence of language. The emotional stimuli were better recognized from visual stimuli than auditory stimuli by both genders. Visual information about speech may not be connected to the language; instead, it may be based on the human ability to understand the kinetic movements in speech production more readily than the characteristics of the acoustic cues.

  4. Bayesian-based integration of multisensory naturalistic perithreshold stimuli.

    Science.gov (United States)

    Regenbogen, Christina; Johansson, Emilia; Andersson, Patrik; Olsson, Mats J; Lundström, Johan N

    2016-07-29

    Most studies exploring multisensory integration have used clearly perceivable stimuli. According to the principle of inverse effectiveness, the added neural and behavioral benefit of integrating clear stimuli is reduced in comparison to stimuli with degraded and less salient unisensory information. Traditionally, speed and accuracy measures have been analyzed separately with few studies merging these to gain an understanding of speed-accuracy trade-offs in multisensory integration. In two separate experiments, we assessed multisensory integration of naturalistic audio-visual objects consisting of individually-tailored perithreshold dynamic visual and auditory stimuli, presented within a multiple-choice task, using a Bayesian Hierarchical Drift Diffusion Model that combines response time and accuracy. For both experiments, unisensory stimuli were degraded to reach a 75% identification accuracy level for all individuals and stimuli to promote multisensory binding. In Experiment 1, we subsequently presented uni- and their respective bimodal stimuli followed by a 5-alternative-forced-choice task. In Experiment 2, we controlled for low-level integration and attentional differences. Both experiments demonstrated significant superadditive multisensory integration of bimodal perithreshold dynamic information. We present evidence that the use of degraded sensory stimuli may provide a link between previous findings of inverse effectiveness on a single neuron level and overt behavior. We further suggest that a combined measure of accuracy and reaction time may be a more valid and holistic approach of studying multisensory integration and propose the application of drift diffusion models for studying behavioral correlates as well as brain-behavior relationships of multisensory integration.

  5. Processing of natural temporal stimuli by macaque retinal ganglion cells

    NARCIS (Netherlands)

    Hateren, J.H. van; Rüttiger, L.; Lee, B.B.

    2002-01-01

    This study quantifies the performance of primate retinal ganglion cells in response to natural stimuli. Stimuli were confined to the temporal and chromatic domains and were derived from two contrasting environments, one typically northern European and the other a flower show. The performance of the

  6. Processing of natural temporal stimuli by macaque retinal ganglion cells

    NARCIS (Netherlands)

    Hateren, J.H. van; Rüttiger, L.; Lee, B.B.

    2002-01-01

    This study quantifies the performance of primate retinal ganglion cells in response to natural stimuli. Stimuli were confined to the temporal and chromatic domains and were derived from two contrasting environments, one typically northern European and the other a flower show. The performance of the

  7. Brain mechanisms that underlie the effects of motivational audiovisual stimuli on psychophysiological responses during exercise.

    Science.gov (United States)

    Bigliassi, Marcelo; Silva, Vinícius B; Karageorghis, Costas I; Bird, Jonathan M; Santos, Priscila C; Altimari, Leandro R

    2016-05-01

    Motivational audiovisual stimuli such as music and video have been widely used in the realm of exercise and sport as a means by which to increase situational motivation and enhance performance. The present study addressed the mechanisms that underlie the effects of motivational stimuli on psychophysiological responses and exercise performance. Twenty-two participants completed fatiguing isometric handgrip-squeezing tasks under two experimental conditions (motivational audiovisual condition and neutral audiovisual condition) and a control condition. Electrical activity in the brain and working muscles was analyzed by use of electroencephalography and electromyography, respectively. Participants were asked to squeeze the dynamometer maximally for 30s. A single-item motivation scale was administered after each squeeze. Results indicated that task performance and situational motivational were superior under the influence of motivational stimuli when compared to the other two conditions (~20% and ~25%, respectively). The motivational stimulus downregulated the predominance of low-frequency waves (theta) in the right frontal regions of the cortex (F8), and upregulated high-frequency waves (beta) in the central areas (C3 and C4). It is suggested that motivational sensory cues serve to readjust electrical activity in the brain; a mechanism by which the detrimental effects of fatigue on the efferent control of working muscles is ameliorated.

  8. A case report of an autistic boy. Selective responding to components of bidimensional visual and auditory stimuli.

    Science.gov (United States)

    Edwards, J L; Shigley, R H; Edwards, R P

    1976-06-01

    A case study was reported in which a 9-year-old male autistic boy was initially trained to discriminate between two auditory stimuli and two visual stimuli. He was then tested for overselective responding to bidimensional combinations of the four stimuli. It was hypothesized that the overselectivity results reported in previous studies were partially a function of a procedure in which autistic children were reinforced for responding in the presence of a multidimensional stimulus complex and then tested with individual stimuli. The child in the present investigation, with the alternative procedure, did not demonstrate overselective responding. Two interpretations of the results were presented, neither of which was consistent with an overselectivity theory. Future research should delineate the specific conditions which produce overselective responding, and suggest methods to facilitate more adaptive responding of autistic children.

  9. Secondary hyperalgesia to heat stimuli after burn injury in man

    DEFF Research Database (Denmark)

    Pedersen, J L; Kehlet, H

    1998-01-01

    was not significantly different between the two zones of hyperalgesia. In conclusion, secondary hyperalgesia in man is not restricted to mechanical stimuli, as significant hyperalgesia to heat developed within the zone of secondary hyperalgesia to punctate mechanical stimuli. The data, combined with other evidence......The aim of the study was to examine the presence of hyperalgesia to heat stimuli within the zone of secondary hyperalgesia to punctate mechanical stimuli. A burn was produced on the medial part of the non-dominant crus in 15 healthy volunteers with a 50 x 25 mm thermode (47 degrees C, 7 min......), and assessments were made 70 min and 40 min before, and 0, 1, and 2 h after the burn injury. Hyperalgesia to mechanical and heat stimuli were examined by von Frey hairs and contact thermodes (3.75 and 12.5 cm2), and pain responses were rated with a visual analog scale (0-100). The area of secondary hyperalgesia...

  10. Secondary hyperalgesia to heat stimuli after burn injury in man

    DEFF Research Database (Denmark)

    Pedersen, J L; Kehlet, H

    1998-01-01

    area). The burns decreased pain thresholds and increased pain responses to both thermal and mechanical stimuli within the burn (P hyperalgesia (mean 89 cm2) to punctate mechanical stimuli (P ...The aim of the study was to examine the presence of hyperalgesia to heat stimuli within the zone of secondary hyperalgesia to punctate mechanical stimuli. A burn was produced on the medial part of the non-dominant crus in 15 healthy volunteers with a 50 x 25 mm thermode (47 degrees C, 7 min......), and assessments were made 70 min and 40 min before, and 0, 1, and 2 h after the burn injury. Hyperalgesia to mechanical and heat stimuli were examined by von Frey hairs and contact thermodes (3.75 and 12.5 cm2), and pain responses were rated with a visual analog scale (0-100). The area of secondary hyperalgesia...

  11. Modulation of Motion Perception of Ipsilateral Tactile Stimuli Using Sound

    Directory of Open Access Journals (Sweden)

    Yuika Suzuki

    2011-10-01

    Full Text Available We report the modulation of tactile motion perception by presenting static sounds with two alternately and repeatedly presented vibrotactile stimuli for the perception of tactile apparent motion. Previous research on tactile motion perception has used direction judgment tasks for apparent motion that consist of two non-repeating, or more than two repeating stimuli. However, the direction of two repeating apparent motion stimuli has been considered too ambiguous to be judged. The present study shows that the additional presentation of sounds with manipulated timings could help to determine the perceived direction of tactile motion despite the ambiguity in the interpretation of tactile stimuli at ipsilateral locations. Furthermore, we found that there is a limited alternation rate for tactile stimuli that can be used to achieve significant modulation using sound. We relate the temporal properties observed during crossmodal effects in tactile motion perception, to those observed during some other crossmodal phenomena.

  12. Emotional attention for erotic stimuli: Cognitive and brain mechanisms.

    Science.gov (United States)

    Sennwald, Vanessa; Pool, Eva; Brosch, Tobias; Delplanque, Sylvain; Bianchi-Demicheli, Francesco; Sander, David

    2016-06-01

    It has long been posited that among emotional stimuli, only negative threatening information modulates early shifts of attention. However, in the last few decades there has been an increase in research showing that attention is also involuntarily oriented toward positive rewarding stimuli such as babies, food, and erotic information. Because reproduction-related stimuli have some of the largest effects among positive stimuli on emotional attention, the present work reviews recent literature and proposes that the cognitive and cerebral mechanisms underlying the involuntarily attentional orientation toward threat-related information are also sensitive to erotic information. More specifically, the recent research suggests that both types of information involuntarily orient attention due to their concern relevance and that the amygdala plays an important role in detecting concern-relevant stimuli, thereby enhancing perceptual processing and influencing emotional attentional processes. © 2015 Wiley Periodicals, Inc.

  13. Volume Entropy

    CERN Document Server

    Astuti, Valerio; Rovelli, Carlo

    2016-01-01

    Building on a technical result by Brunnemann and Rideout on the spectrum of the Volume operator in Loop Quantum Gravity, we show that the dimension of the space of the quadrivalent states --with finite-volume individual nodes-- describing a region with total volume smaller than $V$, has \\emph{finite} dimension, bounded by $V \\log V$. This allows us to introduce the notion of "volume entropy": the von Neumann entropy associated to the measurement of volume.

  14. Autonomous adrenocorticotropin reaction to stress stimuli in human fetus.

    Science.gov (United States)

    Kosinska-Kaczynska, Katarzyna; Bartkowiak, Robert; Kaczynski, Bartosz; Szymusik, Iwona; Wielgos, Miroslaw

    2012-04-01

    The aim of the study was to determine whether human fetuses show ACTH response to stress stimuli, to define the gestational age from which these reactions may be present and to analyze the relationship between hormone concentrations and their changes, both in fetuses and in pregnant women. The study included 81 intrauterine transfusions carried out in 19 pregnant women. 52 procedures were performed directly into the umbilical vein, which is not innervated, so neutral for the fetus (the PCI group) and 29 transfusions into the intrahepatic vein -which puncture is stressful for the fetus (the IHV group). ACTH and cortisol concentrations in fetal and maternal plasma obtained during the procedures were assayed. The initial mean plasma ACTH concentration in the PCI group equaled 18.94pg/mL, but in the IHV group it was significantly higher and amounted 75.17pg/mL (p0.05) and in the PCI group (22.36pg/mL, p>0.05). The observed hormonal response in the IHV group proves the existence of fetal pituitary reaction to stress. The initial fetal ACTH concentration in the IHV group correlated with the number of transfusions performed on a single fetus (R=0.41; p=0.04). No correlation with parity, gestational weeks or the volume of transfused packed red blood cells was found. There was also no correlation between fetal and maternal ACTH concentrations in any group. Presented data suggest that the human fetus shows autonomous ACTH reaction to stress stimulation. Copyright © 2011 Elsevier Ltd. All rights reserved.

  15. Dynamic bioactive stimuli-responsive polymeric surfaces

    Science.gov (United States)

    Pearson, Heather Marie

    This dissertation focuses on the design, synthesis, and development of antimicrobial and anticoagulant surfaces of polyethylene (PE), polypropylene (PP), and poly(tetrafluoroethylene) (PTFE) polymers. Aliphatic polymeric surfaces of PE and PP polymers functionalized using click chemistry reactions by the attachment of --COOH groups via microwave plasma reactions followed by functionalization with alkyne moieties. Azide containing ampicillin (AMP) was synthesized and subsequently clicked into the alkyne prepared PE and PP surfaces. Compared to non-functionalized PP and PE surfaces, the AMP clicked surfaces exhibited substantially enhanced antimicrobial activity against Staphylococcus aureus bacteria. To expand the biocompatibility of polymeric surface anticoagulant attributes, PE and PTFE surfaces were functionalized with pH-responsive poly(2-vinyl pyridine) (P2VP) and poly(acrylic acid) (PAA) polyelectrolyte tethers terminated with NH2 and COOH groups. The goal of these studies was to develop switchable stimuli-responsive polymeric surfaces that interact with biological environments and display simultaneous antimicrobial and anticoagulant properties. Antimicrobial AMP was covalently attached to --COOH terminal ends of protected PAA, while anticoagulant heparin (HEP) was attached to terminal --NH2 groups of P2VP. When pH 5.5, they collapse while the PAA segments extend. Such surfaces, when exposed to Staphylococcus aureus, inhibit bacterial growth due to the presence of AMP, as well as are effective anticoagulants due to the presence of covalently attached HEP. Comparison of these "dynamic" pH responsive surfaces with "static" surfaces terminated with AMP entities show significant enhancement of longevity and surface activity against microbial film formation. The last portion of this dissertation focuses on the covalent attachment of living T1 and Φ11 bacteriophages (phages) on PE and PTFE surface. This was accomplished by carbodiimide coupling between --COOH

  16. Meet the Fribbles: Novel stimuli for use within behavioural research

    Directory of Open Access Journals (Sweden)

    Tom Joseph Barry

    2014-02-01

    Full Text Available Clinical researchers make use of experimental models for mental disorders. In many cases, these models use stimuli that are relevant to the disorder under scrutiny, which allows one to experimentally investigate the factors that contribute to the development of the disorder. For example, one might use spiders or spider-like stimuli in the study of specific phobia. More broadly, researchers often make use of real-world stimuli such as images of animals, geometrical shapes or emotional words. However, these stimuli are often limited in their experimental controllability and their applicability to the disorder in question. We present a novel set of animal-like stimuli, called Fribbles, for use within behavioural research. Fribbles have desirable properties for use in research because they are similar to real-world stimuli, but due to their novelty, participants will not have had previous experience with them. They also have known properties that can be experimentally manipulated. We present an investigation into similarity between Fribbles in order to illustrate their utility in research that relies on comparisons between similar stimuli. Fribbles offer both experimental control and generalisability to the real world, although some consideration must be made concerning the properties that influence similarity between Fribbles when selecting them along a dimension of similarity.

  17. Detection of hydrodynamic stimuli by the postcranial body of Florida manatees (Trichechus manatus latirostris).

    Science.gov (United States)

    Gaspard, Joseph C; Bauer, Gordon B; Mann, David A; Boerner, Katharine; Denum, Laura; Frances, Candice; Reep, Roger L

    2017-02-01

    Manatees live in shallow, frequently turbid waters. The sensory means by which they navigate in these conditions are unknown. Poor visual acuity, lack of echolocation, and modest chemosensation suggest that other modalities play an important role. Rich innervation of sensory hairs that cover the entire body and enlarged somatosensory areas of the brain suggest that tactile senses are good candidates. Previous tests of detection of underwater vibratory stimuli indicated that they use passive movement of the hairs to detect particle displacements in the vicinity of a micron or less for frequencies from 10 to 150 Hz. In the current study, hydrodynamic stimuli were created by a sinusoidally oscillating sphere that generated a dipole field at frequencies from 5 to 150 Hz. Go/no-go tests of manatee postcranial mechanoreception of hydrodynamic stimuli indicated excellent sensitivity but about an order of magnitude less than the facial region. When the vibrissae were trimmed, detection thresholds were elevated, suggesting that the vibrissae were an important means by which detection occurred. Manatees were also highly accurate in two-choice directional discrimination: greater than 90% correct at all frequencies tested. We hypothesize that manatees utilize vibrissae as a three-dimensional array to detect and localize low-frequency hydrodynamic stimuli.

  18. Mexican rice borer (Lepidoptera: Crambidae) oviposition site selection stimuli on sugarcane, and potential field applications.

    Science.gov (United States)

    Showler, Allan T; Castro, Boris A

    2010-08-01

    The Mexican rice borer, Eoreuma loftini (Dyar) (Lepidoptera: Crambidae), a key pest of sugarcane (Saccharum spp.) and rice, Oryza sativa L., in Texas, has not been controlled with chemical insecticides or biological agents, but some sugarcane varieties have shown degrees of resistance. Assessment of selected sugarcane leaf characteristics indicate that preference for oviposition sites is mostly determined by the presence of a leaf fold and secondarily by the availability of dry leaf tissue, both of which are antixenotic nonchemical stimuli. We suggest that breeding sugarcane lines bearing leaves that do not fold on drying could provide substantial antixenotic resistance against the Mexican rice borer. Previously identified antixenotic chemical stimuli, i.e., low quantities or absence of important nutrients in green leaf tissue, only become apparent when resistant and susceptible sugarcane varieties are compared. Varietal differences in oviposition preference, however, were not observed on excised dry leaf tissue, indicating that expression of resistance in terms of chemical stimuli requires detection of biochemicals in nearby living leaf tissue. Excised dry sugarcane leaves retain the two dominant nonchemical oviposition preference stimuli for Mexican rice borers, and the leaves effectively trapped eggs away from intact plants when dry leaves were used as "mulch" at the bottom of greenhouse cages. Under commercial sugarcane field conditions, bundled dry leaves also collected Mexican rice borer eggs. Possible applications of dry sugarcane leaf substrate for egg scouting and for trapping eggs are discussed.

  19. Perceptual Sensitivity and Response to Strong Stimuli Are Related

    Directory of Open Access Journals (Sweden)

    Anna C. Bolders

    2017-09-01

    Full Text Available To shed new light on the long-standing debate about the (independence of sensitivity to weak stimuli and overreactivity to strong stimuli, we examined the relation between these tendencies within the neurobehavioral framework of the Predictive and Reactive Control Systems (PARCS theory (Tops et al., 2010, 2014. Whereas previous studies only considered overreactivity in terms of the individual tendency to experience unpleasant affect (punishment reactivity resulting from strong sensory stimulation, we also took the individual tendency to experience pleasant affect (reward reactivity resulting from strong sensory stimulation into account. According to PARCS theory, these temperamental tendencies overlap in terms of high reactivity toward stimulation, but oppose each other in terms of the response orientation (approach or avoid. PARCS theory predicts that both types of reactivity to strong stimuli relate to sensitivity to weak stimuli, but that these relationships are suppressed due to the opposing relationship between reward and punishment reactivity. We measured punishment and reward reactivity to strong stimuli and sensitivity to weak stimuli using scales from the Adult Temperament Questionnaire (Evans and Rothbart, 2007. Sensitivity was also measured more objectively using the masked auditory threshold. We found that sensitivity to weak stimuli (both self-reported and objectively assessed was positively associated with self-reported punishment and reward reactivity to strong stimuli, but only when these reactivity measures were controlled for each other, implicating a mutual suppression effect. These results are in line with PARCS theory and suggest that sensitivity to weak stimuli and overreactivity are dependent, but this dependency is likely to be obscured if punishment and reward reactivity are not both taken into account.

  20. An updated validation of Promega's PowerPlex 16 System: high throughput databasing under reduced PCR volume conditions on Applied Biosystem's 96 capillary 3730xl DNA Analyzer.

    Science.gov (United States)

    Spathis, Rita; Lum, J Koji

    2008-11-01

    The PowerPlex 16 System from Promega Corporation allows single tube multiplex amplification of sixteen short tandem repeat (STR) loci including all 13 core combined DNA index system STRs. This report presents an updated validation of the PowerPlex 16 System on Applied Biosystem's 96 capillary 3730xl DNA Analyzer. The validation protocol developed in our laboratory allows for the analysis of 1536 loci (96 x 16) in c. 50 min. We have further optimized the assay by decreasing the reaction volume to one-quarter that recommended by the manufacturer thereby substantially reducing the total cost per sample without compromising reproducibility or specificity. This reduction in reaction volume has the ancillary benefit of dramatically increasing the sensitivity of the assay allowing for accurate analysis of lower quantities of DNA. Due to its substantially increased throughput capability, this extended validation of the PowerPlex 16 System should be useful in reducing the backlog of unanalyzed DNA samples currently facing public DNA forensic laboratories.

  1. External-stimuli responsive systems for cancer theranostic

    Directory of Open Access Journals (Sweden)

    Jianhui Yao

    2016-10-01

    Full Text Available The upsurge of novel nanomaterials and nanotechnologies has inspired the researchers who are striving for designing safer and more efficient drug delivery systems for cancer therapy. Stimuli responsive nanomaterial offered an alternative to design controllable drug delivery system on account of its spatiotemporally controllable properties. Additionally, external stimuli (light, magnetic field and ultrasound could develop into theranostic applications for personalized medicine use because of their unique characteristics. In this review, we give a brief overview about the significant progresses and challenges of certain external-stimuli responsive systems that have been extensively investigated in drug delivery and theranostics within the last few years.

  2. Response properties of cat AMLS neurons to optic flow stimuli

    Institute of Scientific and Technical Information of China (English)

    LI; Baowang(李宝旺); LI; Bing(李兵); CHEN; Hui(陈辉); XU; Ying(徐颖); DIAO; Yuncheng(刁云程)

    2002-01-01

    Spiral and translation stimuli were used to investigate the response properties of cat AMLS (anteromedial lateral suprasylvian area) neurons to optic flow. The overwhelming majority of cells could be significantly excited by the two modes of stimuli and most responsive cells displayed obvious direction selectivity. It is the first time to find a visual area in mammalian brain preferring rotation stimuli. Two representative hypotheses are discussed here on the neural mechanism of optic flow analysis in visual cortex, and some new viewpoints are proposed to explain the experimental results.

  3. Differences in cortical response to acupressure and electroacupuncture stimuli

    Directory of Open Access Journals (Sweden)

    Vangel Mark G

    2011-07-01

    Full Text Available Abstract Background FMRI studies focus on sub-cortical effects of acupuncture stimuli. The purpose of this study was to assess changes in primary somatosensory (S1 activity over the course of different types of acupuncture stimulation. We used whole head magnetoencephalography (MEG to map S1 brain response during 15 minutes of electroacupuncture (EA and acupressure (AP. We further assessed how brain response changed during the course of stimulation. Results Evoked brain response to EA differed from AP in its temporal dynamics by showing clear contralateral M20/M30 peaks while the latter demonstrated temporal dispersion. Both EA and AP demonstrated significantly decreased response amplitudes following five minutes of stimulation. However, the latency of these decreases were earlier in EA (~30 ms post-stimulus than AP (> 100 ms. Time-frequency responses demonstrated early onset, event related synchronization (ERS, within the gamma band at ~70-130 ms and the theta band at ~50-200 ms post-stimulus. A prolonged event related desynchronization (ERD of alpha and beta power occurred at ~100-300 ms post-stimulus. There was decreased beta ERD at ~100-300 ms over the course of EA, but not AP. Conclusion Both EA and AP demonstrated conditioning of SI response. In conjunction with their subcortical effects on endogenous pain regulation, these therapies show potential for affecting S1 processing and possibly altering maladaptive neuroplasticity. Thus, further investigation in neuropathic populations is needed.

  4. Under conditions of large geometric miss, tumor control probability can be higher for static gantry intensity-modulated radiation therapy compared to volume-modulated arc therapy for prostate cancer

    Energy Technology Data Exchange (ETDEWEB)

    Balderson, Michael, E-mail: michael.balderson@rmp.uhn.ca; Brown, Derek; Johnson, Patricia; Kirkby, Charles

    2016-07-01

    The purpose of this work was to compare static gantry intensity-modulated radiation therapy (IMRT) with volume-modulated arc therapy (VMAT) in terms of tumor control probability (TCP) under scenarios involving large geometric misses, i.e., those beyond what are accounted for when margin expansion is determined. Using a planning approach typical for these treatments, a linear-quadratic–based model for TCP was used to compare mean TCP values for a population of patients who experiences a geometric miss (i.e., systematic and random shifts of the clinical target volume within the planning target dose distribution). A Monte Carlo approach was used to account for the different biological sensitivities of a population of patients. Interestingly, for errors consisting of coplanar systematic target volume offsets and three-dimensional random offsets, static gantry IMRT appears to offer an advantage over VMAT in that larger shift errors are tolerated for the same mean TCP. For example, under the conditions simulated, erroneous systematic shifts of 15 mm directly between or directly into static gantry IMRT fields result in mean TCP values between 96% and 98%, whereas the same errors on VMAT plans result in mean TCP values between 45% and 74%. Random geometric shifts of the target volume were characterized using normal distributions in each Cartesian dimension. When the standard deviations were doubled from those values assumed in the derivation of the treatment margins, our model showed a 7% drop in mean TCP for the static gantry IMRT plans but a 20% drop in TCP for the VMAT plans. Although adding a margin for error to a clinical target volume is perhaps the best approach to account for expected geometric misses, this work suggests that static gantry IMRT may offer a treatment that is more tolerant to geometric miss errors than VMAT.

  5. Elemental Representations of Stimuli in Associative Learning

    Science.gov (United States)

    Harris, Justin A.

    2006-01-01

    This article reviews evidence and theories concerning the nature of stimulus representations in Pavlovian conditioning. It focuses on the elemental approach developed in stimulus sampling theory (R. C. Atkinson & W. K. Estes, 1963; R. R. Bush & F. Mosteller, 1951b) and extended by I. P. L. McLaren and N. J. Mackintosh (2000, 2002) and contrasts…

  6. Physiological and behavioral reactions elicited by simulated and real-life visual and acoustic helicopter stimuli in dairy goats

    Directory of Open Access Journals (Sweden)

    Joosse Martin

    2011-04-01

    Full Text Available Abstract Background Anecdotal reports and a few scientific publications suggest that flyovers of helicopters at low altitude may elicit fear- or anxiety-related behavioral reactions in grazing feral and farm animals. We investigated the behavioral and physiological stress reactions of five individually housed dairy goats to different acoustic and visual stimuli from helicopters and to combinations of these stimuli under controlled environmental (indoor conditions. The visual stimuli were helicopter animations projected on a large screen in front of the enclosures of the goats. Acoustic and visual stimuli of a tractor were also presented. On the final day of the study the goats were exposed to two flyovers (altitude 50 m and 75 m of a Chinook helicopter while grazing in a pasture. Salivary cortisol, behavior, and heart rate of the goats were registered before, during and after stimulus presentations. Results The goats reacted alert to the visual and/or acoustic stimuli that were presented in their room. They raised their heads and turned their ears forward in the direction of the stimuli. There was no statistically reliable rise of the average velocity of moving of the goats in their enclosure and no increase of the duration of moving during presentation of the stimuli. Also there was no increase in heart rate or salivary cortisol concentration during the indoor test sessions. Surprisingly, no physiological and behavioral stress responses were observed during the flyover of a Chinook at 50 m, which produced a peak noise of 110 dB. Conclusions We conclude that the behavior and physiology of goats are unaffected by brief episodes of intense, adverse visual and acoustic stimulation such as the sight and noise of overflying helicopters. The absence of a physiological stress response and of elevated emotional reactivity of goats subjected to helicopter stimuli is discussed in relation to the design and testing schedule of this study.

  7. Group behavioural responses of Atlantic salmon (Salmo salar L. to light, infrasound and sound stimuli.

    Directory of Open Access Journals (Sweden)

    Samantha Bui

    Full Text Available Understanding species-specific flight behaviours is essential in developing methods of guiding fish spatially, and requires knowledge on how groups of fish respond to aversive stimuli. By harnessing their natural behaviours, the use of physical manipulation or other potentially harmful procedures can be minimised. We examined the reactions of sea-caged groups of 50 salmon (1331 ± 364 g to short-term exposure to visual or acoustic stimuli. In light experiments, fish were exposed to one of three intensities of blue LED light (high, medium and low or no light (control. Sound experiments included exposure to infrasound (12 Hz, a surface disturbance event, the combination of infrasound and surface disturbance, or no stimuli. Groups that experienced light, infrasound, and the combination of infrasound and surface disturbance treatments, elicited a marked change in vertical distribution, where fish dived to the bottom of the sea-cage for the duration of the stimulus. Light treatments, but not sound, also reduced the total echo-signal strength (indicative of swim bladder volume after exposure to light, compared to pre-stimulus levels. Groups in infrasound and combination treatments showed increased swimming activity during stimulus application, with swimming speeds tripled compared to that of controls. In all light and sound treatments, fish returned to their pre-stimulus swimming depths and speeds once exposure had ceased. This work establishes consistent, short-term avoidance responses to these stimuli, and provides a basis for methods to guide fish for aquaculture applications, or create avoidance barriers for conservation purposes. In doing so, we can achieve the manipulation of group position with minimal welfare impacts, to create more sustainable practices.

  8. Effects of caffeine, caffeine-associated stimuli, and caffeine-related information on physiological and psychological arousal.

    Science.gov (United States)

    Mikalsen, A; Bertelsen, B; Flaten, M A

    2001-10-01

    To test the classical conditioning and expectancy theories of placebo effects. Two experiments investigated whether administration of caffeine-associated stimuli elicited conditioned arousal, and whether information that a drink contained or did not contain caffeine modulated arousal. Experiment 1 (n=21) used a 2 Caffeine (0 and 2 mg/kg) x 2 Solution (Coffee, Juice) x 2 Information (Told caffeine, Told not-caffeine) within-subjects design. Experiment 2 (n=48) used a 2 Solution (Coffee, Orange juice) x 3 Information (Told caffeine, Told not-caffeine, No information) between-subjects design. Indexes of arousal were skin conductance responses and levels, startle eyeblink reflexes, cardiovascular measures, and the Bond and Lader 1974 mood scale. Caffeine-associated stimuli increased alertness, contentedness and skin conductance levels, and information that the drink contained caffeine decreased calmness in Experiment 1. However, unexpected information about the caffeine content of the drink, and the order of the conditions, could have masked some effects of the experimental manipulations. Experiment 2 followed up this hypothesis. The results showed a conditioned increase in startle eyeblink reflexes, and that caffeine-associated stimuli together with information that the drink contained caffeine increased contentedness. Caffeine-associated stimuli increased arousal, and information about the content of the drink modulated arousal in the direction indicated by the information. Thus, both the classical conditioning and expectancy theories of placebo effects received support, and placebo effects were strongest when both conditioned responses and expectancy-based responses acted in the same direction.

  9. Do extraverts process social stimuli differently from introverts?

    Science.gov (United States)

    Fishman, Inna; Ng, Rowena; Bellugi, Ursula

    2011-01-01

    The personality trait of extraversion has been linked to the network of brain systems controlling sensitivity to cues of reward and generating approach behavior in response, but little is known about whether extraverts' neural circuits are especially sensitive to social stimuli, given their preference for social engagement. Utilizing event-related potential (ERP) methodology, this study demonstrates that variation on the extraversion dimension is associated with the extent to which social stimuli evoke enhanced allocation of attention. Specifically, higher scores on extraversion were found to be associated with higher amplitudes of the P300 component of the ERPs elicited by human faces. This finding suggests that social stimuli carry enhanced motivational significance for individuals characterized by high extraversion, and that individual differences in personality are related to meaningful individual differences in neural responses to social stimuli.

  10. Marijuana effects on associations to novel stimuli.

    Science.gov (United States)

    Tinklenberg, J R; Darley, C F; Roth, W T; Pfefferbaum, A; Kopell, B S

    1978-05-01

    Sixteen college-educated male subjects were given an object description task during placebo conditions and while intoxicated with marijuana extract cookies calibrated to 0.3 mg/kg delta-9-tetrahydrocannabinol, a dose within the range of usual social use. The task was scored for fluency, flexibility, elaboration, and uniqueness, all of which represent associational thinking and are considered to be components of creativity. Marijuana did not enhance any of these measures.

  11. Prefrontal cortex neurons reflect categorical decisions about ambiguous stimuli

    OpenAIRE

    Roy, Jefferson E.; Buschman, Timothy J.; Miller, Earl K

    2014-01-01

    We examined whether prefrontal cortex (PFC) neuron activity reflects categorical decisions in monkeys categorizing ambiguous stimuli. A morphing system was used to systematically vary stimulus shape and precisely define category boundaries. Ambiguous stimuli were centered on a category boundary, i.e., they were a mix of 50% of two prototypes and therefore had no category information, so monkeys guessed at their category membership. We found that the monkey's trial-by-trial decision about the ...

  12. Oral perceptions of fat and taste stimuli are modulated by affect and mood induction.

    Directory of Open Access Journals (Sweden)

    Petra Platte

    Full Text Available This study examined the impact of three clinical psychological variables (non-pathological levels of depression and anxiety, as well as experimentally manipulated mood on fat and taste perception in healthy subjects. After a baseline orosensory evaluation, 'sad', 'happy' and 'neutral' video clips were presented to induce corresponding moods in eighty participants. Following mood manipulation, subjects rated five different oral stimuli, appearing sweet, umami, sour, bitter, fatty, which were delivered at five different concentrations each. Depression levels were assessed with Beck's Depression Inventory (BDI and anxiety levels were assessed via the Spielberger's STAI-trait and state questionnaire. Overall, subjects were able to track the concentrations of the stimuli correctly, yet depression level affected taste ratings. First, depression scores were positively correlated with sucrose ratings. Second, subjects with depression scores above the sample median rated sucrose and quinine as more intense after mood induction (positive, negative and neutral. Third and most important, the group with enhanced depression scores did not rate low and high fat stimuli differently after positive or negative mood induction, whereas, during baseline or during the non-emotional neutral condition they rated the fat intensity as increasing with concentration. Consistent with others' prior observations we also found that sweet and bitter stimuli at baseline were rated as more intense by participants with higher anxiety scores and that after positive and negative mood induction, citric acid was rated as stronger tasting compared to baseline. The observation that subjects with mild subclinical depression rated low and high fat stimuli similarly when in positive or negative mood is novel and likely has potential implications for unhealthy eating patterns. This deficit may foster unconscious eating of fatty foods in sub-clinical mildly depressed populations.

  13. Bitter taste stimuli induce differential neural codes in mouse brain.

    Directory of Open Access Journals (Sweden)

    David M Wilson

    Full Text Available A growing literature suggests taste stimuli commonly classified as "bitter" induce heterogeneous neural and perceptual responses. Here, the central processing of bitter stimuli was studied in mice with genetically controlled bitter taste profiles. Using these mice removed genetic heterogeneity as a factor influencing gustatory neural codes for bitter stimuli. Electrophysiological activity (spikes was recorded from single neurons in the nucleus tractus solitarius during oral delivery of taste solutions (26 total, including concentration series of the bitter tastants quinine, denatonium benzoate, cycloheximide, and sucrose octaacetate (SOA, presented to the whole mouth for 5 s. Seventy-nine neurons were sampled; in many cases multiple cells (2 to 5 were recorded from a mouse. Results showed bitter stimuli induced variable gustatory activity. For example, although some neurons responded robustly to quinine and cycloheximide, others displayed concentration-dependent activity (p<0.05 to quinine but not cycloheximide. Differential activity to bitter stimuli was observed across multiple neurons recorded from one animal in several mice. Across all cells, quinine and denatonium induced correlated spatial responses that differed (p<0.05 from those to cycloheximide and SOA. Modeling spatiotemporal neural ensemble activity revealed responses to quinine/denatonium and cycloheximide/SOA diverged during only an early, at least 1 s wide period of the taste response. Our findings highlight how temporal features of sensory processing contribute differences among bitter taste codes and build on data suggesting heterogeneity among "bitter" stimuli, data that challenge a strict monoguesia model for the bitter quality.

  14. Effect of stimuli presentation method on perception of room size using only acoustic cues

    Science.gov (United States)

    Hunt, Jeffrey Barnabas

    People listen to music and speech in a large variety of rooms and many room parameters, including the size of the room, can drastically affect how well the speech is understood or the music enjoyed. While multi-modal (typically hearing and sight) tests may be more realistic, in order to isolate what acoustic cues listeners use to determine the size of a room, a listening-only tests is conducted here. Nearly all of the studies to-date on the perception of room volume using acoustic cues have presented the stimuli only over headphones and these studies have reported that, in most cases, the perceived room volume is more highly correlated with the perceived reverberation (reverberance) than with actual room volume. While reverberance may be a salient acoustic cue used for the determination or room size, the actual sound field in a room is not accurately reproduced when presented over headphones and it is thought that some of the complexities of the sound field that relate to perception of geometric volume, specifically directional information of reflections, may be lost. It is possible that the importance of reverberance may be overemphasized when using only headphones to present stimuli so a comparison of room-size perception is proposed where the sound field (from modeled and recorded impulse responses) is presented both over headphones and also over a surround system using higher order ambisonics to more accurately produce directional sound information. Major results are that, in this study, no difference could be seen between the two presentation methods and that reverberation time is highly correlated to room-size perception while real room size is not.

  15. Face and voice as social stimuli enhance differential physiological responding in a Concealed Information Test

    Directory of Open Access Journals (Sweden)

    Wolfgang eAmbach

    2012-11-01

    Full Text Available Attentional, intentional, and motivational factors are known to influence the physiological responses in a Concealed Information Test (CIT. Although concealing information is essentially a social action closely related to motivation, CIT studies typically rely on testing participants in an environment lacking of social stimuli: Subjects interact with a computer while sitting alone in an experimental room. To address this gap, we examined the influence of social stimuli on the physiological responses in a CIT.Seventy-one participants underwent a mock-crime experiment with a modified CIT. In a between-subjects design, subjects were either questioned acoustically by a pre-recorded male voice presented together with a virtual male experimenter’s uniform face or by a text field on the screen, which displayed the question devoid of face and voice. Electrodermal activity (EDA, respiration line length (RLL, phasic heart rate (pHR, and finger pulse waveform length (FPWL were registered. The Psychopathic Personality Inventory - Revised (PPI-R was administered in addition. The differential responses of RLL, pHR, and FPWL to probe vs. irrelevant items were greater in the condition with social stimuli than in the text condition; interestingly, the differential responses of EDA did not differ between conditions. No modulatory influence of the PPI-R sum or subscale scores was found.The results emphasize the relevance of social aspects in the process of concealing information and in its detection. Attentional demands as well as the participants’ motivation to avoid detection might be the important links between social stimuli and physiological responses in the CIT.

  16. Stimuli responsive deswelling of radiation synthesized collagen hydrogel in simulated physiological environment.

    Science.gov (United States)

    Zhang, Xiangmei; Xu, Ling; Wei, Shicheng; Zhai, Maolin; Li, Jiuqiang

    2013-08-01

    Collagen hydrogels were prepared via radiation crosslinking. The simulated physiological environmental effects related to their biomedical applications on the volume phase transition of collagen hydrogel were studied, that is stimuli response to ions, temperature, and pH. The deswelling behavior of collagen hydrogel depends on the salt concentration, temperature, pH, and the hydrogel preparation procedure. Meanwhile, hydrogel structure related to the volume phase transition was investigated by FTIR, fluorescence spectrum, and HR-MAS NMR. Deswelling in salt solution caused little change on collagen conformation, and a denser network led to more significant tyrosine-derived fluorescence quenching. Hydrogen bonding between hydrated water and collagen polypeptide chain was dissociated and the activity of hydrophobic side chain increased, inducing a higher extent of contraction with the increasing of salt concentration. Moreover, salt solution treatments weakened the electrostatic interactions, side chains interactions, and hydrogen bonding of collagen hydrogel, which reduced the thermal stability of collagen hydrogel. Comparing with cell-free collagen hydrogel contraction, fibroblasts did not aggravate contraction of collagen hydrogel significantly. This study elucidated the deswelling mechanism of radiation crosslinked collagen hydrogel in simulated physiological environment and provides strategies for controlling the stimuli response of collagen hydrogel in biomedical application.

  17. Visualizing phase transition behavior of dilute stimuli responsive polymer solutions via Mueller matrix polarimetry.

    Science.gov (United States)

    Narayanan, Amal; Chandel, Shubham; Ghosh, Nirmalya; De, Priyadarsi

    2015-09-15

    Probing volume phase transition behavior of superdiluted polymer solutions both micro- and macroscopically still persists as an outstanding challenge. In this regard, we have explored 4 × 4 spectral Mueller matrix measurement and its inverse analysis for excavating the microarchitectural facts about stimuli responsiveness of "smart" polymers. Phase separation behavior of thermoresponsive poly(N-isopropylacrylamide) (PNIPAM) and pH responsive poly(N,N-(dimethylamino)ethyl methacrylate) (PDMAEMA) and their copolymers were analyzed in terms of Mueller matrix derived polarization parameters, namely, depolarization (Δ), diattenuation (d), and linear retardance (δ). The Δ, d, and δ parameters provided useful information on both macro- and microstructural alterations during the phase separation. Additionally, the two step action ((i) breakage of polymer-water hydrogen bonding and (ii) polymer-polymer aggregation) at the molecular microenvironment during the cloud point generation was successfully probed via these parameters. It is demonstrated that, in comparison to the present techniques available for assessing the hydrophobic-hydrophilic switch over of simple stimuli-responsive polymers, Mueller matrix polarimetry offers an important advantage requiring a few hundred times dilute polymer solution (0.01 mg/mL, 1.1-1.4 μM) at a low-volume format.

  18. The End Noise Control of Variable Air Volume Air-Conditioning System%变风量空调系统末端噪声控制

    Institute of Scientific and Technical Information of China (English)

    曹勤

    2012-01-01

    The variable air volume(VAV) air conditioning system with its huge energy advantage more and more widely used.But interior excessive noise problems make installation and debugging personnel feel awkward.In this paper,according to the actual VAV air conditioning system problems in some high-grade building appeared in the construction process,analyzing the end noise source of VAV air conditioning system,making use of the noise attenuation of each part of end unit and noise control at the end is resaerched,and the measures of end noise control are put forward in VAV air conditioning system.%变风量空调系统以其巨大的节能优势越来越得到广泛应用,但是室内噪声超标的问题令安装、调试人员感到棘手。根据实际参加某高档楼盘变风量空调系统建设过程中出现的问题,通过分析变风量空调系统末端噪声的来源,研究利用末端单元各部分噪声的衰减影响来控制末端噪声,提出了变风量空调系统未端噪声的具体控制措施。

  19. Air Conditioning and Refrigeration. Volume XXVI. 1975 Edition of Course of Study Outlines. Middlesex County Vocational and Technical High Schools and Middlesex County Adult Technical Schools.

    Science.gov (United States)

    Capizzi, James

    The two courses of study described and outlined here are offered at Burr D. Coe Vocational and Technical High School in East Brunswick, New Jersey, for students wishing to prepare for a career in air conditioning and refrigeration. Section 1 deals with a 4-year high school course, Section 2 with a 1-year course for those who have completed high…

  20. Conditional ablation of myeloid TNF increases lesion volume after experimental stroke in mice, possibly via altered ERK1/2 signaling

    DEFF Research Database (Denmark)

    Clausen, Bettina Hjelm; Degn, Matilda; Sivasaravanaparan, Mithula

    2016-01-01

    Microglia are activated following cerebral ischemia and increase their production of the neuro- and immunomodulatory cytokine tumor necrosis factor (TNF). To address the function of TNF from this cellular source in focal cerebral ischemia we used TNF conditional knock out mice (LysMcreTNF(fl/fl))...

  1. Voluntary movement affects simultaneous perception of auditory and tactile stimuli presented to a non-moving body part.

    Science.gov (United States)

    Hao, Qiao; Ora, Hiroki; Ogawa, Ken-Ichiro; Ogata, Taiki; Miyake, Yoshihiro

    2016-09-13

    The simultaneous perception of multimodal sensory information has a crucial role for effective reactions to the external environment. Voluntary movements are known to occasionally affect simultaneous perception of auditory and tactile stimuli presented to the moving body part. However, little is known about spatial limits on the effect of voluntary movements on simultaneous perception, especially when tactile stimuli are presented to a non-moving body part. We examined the effect of voluntary movement on the simultaneous perception of auditory and tactile stimuli presented to the non-moving body part. We considered the possible mechanism using a temporal order judgement task under three experimental conditions: voluntary movement, where participants voluntarily moved their right index finger and judged the temporal order of auditory and tactile stimuli presented to their non-moving left index finger; passive movement; and no movement. During voluntary movement, the auditory stimulus needed to be presented before the tactile stimulus so that they were perceived as occurring simultaneously. This subjective simultaneity differed significantly from the passive movement and no movement conditions. This finding indicates that the effect of voluntary movement on simultaneous perception of auditory and tactile stimuli extends to the non-moving body part.

  2. Voluntary movement affects simultaneous perception of auditory and tactile stimuli presented to a non-moving body part

    Science.gov (United States)

    Hao, Qiao; Ora, Hiroki; Ogawa, Ken-ichiro; Ogata, Taiki; Miyake, Yoshihiro

    2016-01-01

    The simultaneous perception of multimodal sensory information has a crucial role for effective reactions to the external environment. Voluntary movements are known to occasionally affect simultaneous perception of auditory and tactile stimuli presented to the moving body part. However, little is known about spatial limits on the effect of voluntary movements on simultaneous perception, especially when tactile stimuli are presented to a non-moving body part. We examined the effect of voluntary movement on the simultaneous perception of auditory and tactile stimuli presented to the non-moving body part. We considered the possible mechanism using a temporal order judgement task under three experimental conditions: voluntary movement, where participants voluntarily moved their right index finger and judged the temporal order of auditory and tactile stimuli presented to their non-moving left index finger; passive movement; and no movement. During voluntary movement, the auditory stimulus needed to be presented before the tactile stimulus so that they were perceived as occurring simultaneously. This subjective simultaneity differed significantly from the passive movement and no movement conditions. This finding indicates that the effect of voluntary movement on simultaneous perception of auditory and tactile stimuli extends to the non-moving body part. PMID:27622584

  3. Facial reactions in response to dynamic emotional stimuli in different modalities in patients suffering from schizophrenia: a behavioral and EMG study

    Directory of Open Access Journals (Sweden)

    Mariateresa eSestito

    2013-07-01

    Full Text Available Emotional facial expression is an important low-level mechanism contributing to the experience of empathy, thereby lying at the core of social interaction. Schizophrenia is associated with pervasive social cognitive impairments, including emotional processing of facial expressions. In this study we test a novel paradigm in order to investigate the evaluation of the emotional content of perceived emotions presented through dynamic expressive stimuli, facial mimicry evoked by the same stimuli, and their functional relation. Fifteen healthy controls and 15 patients diagnosed with schizophrenia were presented with stimuli portraying positive (laugh, negative (cry and neutral (control emotional stimuli in visual, auditory modalities in isolation, and congruently or incongruently associated. Participants where requested to recognize and quantitatively rate the emotional value of the perceived stimuli, while electromyographic activity of Corrugator and Zygomaticus muscles was recorded. All participants correctly judged the perceived emotional stimuli and prioritized the visual over the auditory modality in identifying the emotion when they were incongruently associated (Audio-Video Incongruent condition. The neutral emotional stimuli did not evoke any muscle responses and were judged by all participants as emotionally neutral. Control group responded with rapid and congruent mimicry to emotional stimuli, and in Incongruent condition muscle responses were driven by what participants saw rather than by what they heard. Patient group showed a similar pattern only with respect to negative stimuli, whereas showed a lack of or a non-specific Zygomaticus response when positive stimuli were presented. Finally, we found that only patients with reduced facial mimicry (Internalizers judged both positive and negative emotions as significantly more neutral than controls. The relevance of these findings for studying emotional deficits in schizophrenia is discussed.

  4. Effects of facial attractiveness on personality stimuli in an implicit priming task: an ERP study.

    Science.gov (United States)

    Zhang, Yan; Zheng, Minxiao; Wang, Xiaoying

    2016-08-01

    Using event-related potentials (ERPs) in a priming paradigm, this study examines implicit priming in the association of personality words with facial attractiveness. A total of 16 participants (8 males and 8 females; age range, 19-24 years; mean age, 21.30 years) were asked to judge the color (red and green) of positive or negative personality words after exposure to priming stimuli (attractive and unattractive facial images). The positive personality words primed by attractive faces or the negative personality words primed by unattractive faces were defined as congruent trials, whereas the positive personality words primed by unattractive faces or the negative personality words primed by attractive faces were defined as incongruent trials. Behavioral results showed that compared with the unattractive faces trials, the trials that attractive faces being the priming stimuli had longer reaction times and higher accuracy rates. Moreover, a more negative ERP deflection (N2) component was observed in the ERPs of the incongruent condition than in the ERPs of the congruent condition. In addition, the personality words presented after the attractive faces elicited larger amplitudes from the frontal region to the central region (P2 and P350-550 ms) compared with the personality words after unattractive faces as priming stimuli. The study provides evidence for the facial attractiveness stereotype ('What is beautiful is good') through an implicit priming task.

  5. Mid-adolescent neurocognitive development of ignoring and attending emotional stimuli.

    Science.gov (United States)

    Vetter, Nora C; Pilhatsch, Maximilian; Weigelt, Sarah; Ripke, Stephan; Smolka, Michael N

    2015-08-01

    Appropriate reactions toward emotional stimuli depend on the distribution of prefrontal attentional resources. In mid-adolescence, prefrontal top-down control systems are less engaged, while subcortical bottom-up emotional systems are more engaged. We used functional magnetic resonance imaging to follow the neural development of attentional distribution, i.e. attending versus ignoring emotional stimuli, in adolescence. 144 healthy adolescents were studied longitudinally at age 14 and 16 while performing a perceptual discrimination task. Participants viewed two pairs of stimuli--one emotional, one abstract--and reported on one pair whether the items were the same or different, while ignoring the other pair. Hence, two experimental conditions were created: "attending emotion/ignoring abstract" and "ignoring emotion/attending abstract". Emotional valence varied between negative, positive, and neutral. Across conditions, reaction times and error rates decreased and activation in the anterior cingulate and inferior frontal gyrus increased from age 14 to 16. In contrast, subcortical regions showed no developmental effect. Activation of the anterior insula increased across ages for attending positive and ignoring negative emotions. Results suggest an ongoing development of prefrontal top-down resources elicited by emotional attention from age 14 to 16 while activity of subcortical regions representing bottom-up processing remains stable.

  6. Audiovisual Integration Delayed by Stimulus Onset Asynchrony Between Auditory and Visual Stimuli in Older Adults.

    Science.gov (United States)

    Ren, Yanna; Yang, Weiping; Nakahashi, Kohei; Takahashi, Satoshi; Wu, Jinglong

    2017-02-01

    Although neuronal studies have shown that audiovisual integration is regulated by temporal factors, there is still little knowledge about the impact of temporal factors on audiovisual integration in older adults. To clarify how stimulus onset asynchrony (SOA) between auditory and visual stimuli modulates age-related audiovisual integration, 20 younger adults (21-24 years) and 20 older adults (61-80 years) were instructed to perform an auditory or visual stimuli discrimination experiment. The results showed that in younger adults, audiovisual integration was altered from an enhancement (AV, A ± 50 V) to a depression (A ± 150 V). In older adults, the alterative pattern was similar to that for younger adults with the expansion of SOA; however, older adults showed significantly delayed onset for the time-window-of-integration and peak latency in all conditions, which further demonstrated that audiovisual integration was delayed more severely with the expansion of SOA, especially in the peak latency for V-preceded-A conditions in older adults. Our study suggested that audiovisual facilitative integration occurs only within a certain SOA range (e.g., -50 to 50 ms) in both younger and older adults. Moreover, our results confirm that the response for older adults was slowed and provided empirical evidence that integration ability is much more sensitive to the temporal alignment of audiovisual stimuli in older adults.

  7. Unconscious neural processing differs with method used to render stimuli invisible

    Directory of Open Access Journals (Sweden)

    Sergey Victor Fogelson

    2014-06-01

    Full Text Available Visual stimuli can be kept from awareness using various methods. The extent of processing that a given stimulus receives in the absence of awareness is typically used to make claims about the role of consciousness more generally. The neural processing elicited by a stimulus, however, may also depend on the method used to keep it from awareness, and not only on whether the stimulus reaches awareness. Here we report that the method used to render an image invisible has a dramatic effect on how category information about the unseen stimulus is encoded across the human brain. We collected fMRI data while subjects viewed images of faces and tools, that were rendered invisible using either continuous flash suppression (CFS or chromatic flicker fusion (CFF. In a third condition, we presented the same images under normal fully visible viewing conditions. We found that category information about visible images could be extracted from patterns of fMRI responses throughout areas of neocortex known to be involved in face or tool processing. However, category information about stimuli kept from awareness using CFS could be recovered exclusively within occipital cortex, whereas information about stimuli kept from awareness using CFF was also decodable within temporal and frontal regions. We conclude that unconsciously presented objects are processed differently depending on how they are rendered subjectively invisible. Caution should therefore be used in making generalizations on the basis of any one method about the neural basis of consciousness or the extent of information processing without consciousness.

  8. Mid-adolescent neurocognitive development of ignoring and attending emotional stimuli

    Directory of Open Access Journals (Sweden)

    Nora C. Vetter

    2015-08-01

    Full Text Available Appropriate reactions toward emotional stimuli depend on the distribution of prefrontal attentional resources. In mid-adolescence, prefrontal top-down control systems are less engaged, while subcortical bottom-up emotional systems are more engaged. We used functional magnetic resonance imaging to follow the neural development of attentional distribution, i.e. attending versus ignoring emotional stimuli, in adolescence. 144 healthy adolescents were studied longitudinally at age 14 and 16 while performing a perceptual discrimination task. Participants viewed two pairs of stimuli – one emotional, one abstract – and reported on one pair whether the items were the same or different, while ignoring the other pair. Hence, two experimental conditions were created: “attending emotion/ignoring abstract” and “ignoring emotion/attending abstract”. Emotional valence varied between negative, positive, and neutral. Across conditions, reaction times and error rates decreased and activation in the anterior cingulate and inferior frontal gyrus increased from age 14 to 16. In contrast, subcortical regions showed no developmental effect. Activation of the anterior insula increased across ages for attending positive and ignoring negative emotions. Results suggest an ongoing development of prefrontal top-down resources elicited by emotional attention from age 14 to 16 while activity of subcortical regions representing bottom-up processing remains stable.

  9. 生长模型驱动的杉木林蓄积量动态可视化%Dynamic visualization of Chinese fir volume driven by site condition and growth model

    Institute of Scientific and Technical Information of China (English)

    许炜敏; 陈友飞; 林广发; 陈明华

    2011-01-01

    树木的生长不仅受到自身遗传因素的影响而且还受外界环境条件的影响.以杉木为例,基于实测数据建立的蓄积量随林龄增长的生长模型以及影响林木生长的立地因子,以实现林分中的杉木林蓄积量可视化表达.在3D Max中构建了杉木三维形态几何模型,结合杉木生长模型与形态模型,采用AE+VB.NET编程,实现了基于ArcScene的杉木林蓄积量动态可视化,能直观地反映杉木林蓄积量随立地条件和生长模型的生长状况,对于林业生产信息化和林场的管理、经营和决策具有很大的实用价值.%The growth of the trees is influenced not only by genetic factors and also by extemal environmental conditions. Taking Chinese firs for example, this paper, based on measured data, established the growth model of volume correlated to the stand age and site factors that influence the growth of trees. The research is helpful to realize the visualization of Chinesefir stand volume.Three-dimensional geometric model of Chinese fir is constructed through 3D Max. On the basis of the growth model and the configuration model of Chinese fir, the dynamic visualization d Chinese fir volume was realized based on ArcScene by adopting AE + VB. NET programming. It is possible to directly manifest the growth conditions of Chinese fir volume according to the site conditions and growth model and is of high practical value to forestry production information, the management, operation and strategy of the forest farm.

  10. Cells and stimuli in small-caliber blood vessel tissue engineering.

    Science.gov (United States)

    Tresoldi, Claudia; Pellegata, Alessandro Filippo; Mantero, Sara

    2015-05-01

    The absence of successful solutions in treatments of small-caliber vessel diseases led to the Vascular Tissue Engineering approach to develop functional nonimmunogenic tissue engineered blood vessels. In this context, the choice of cells to be seeded and the microenvironment conditioning are pivotal. Biochemical and biomechanical stimuli seem to activate physiological regulatory pathways that induce the production of molecules and proteins stimulating stem cell differentiation toward vascular lineage and reproducing natural cross-talks among vascular cells to improve the maturation of tissue engineered blood vessels. Thus, this review focuses on (1) available cell sources, and (2) biochemical and biomechanical stimuli, with the final aim to obtain the long-term stability of the endothelium and mechanical properties suitable for withstanding physiological load.

  11. Effect of sensory stimuli on restless legs syndrome: a randomized crossover study.

    Science.gov (United States)

    Rozeman, Anouk D; Ottolini, Truus; Grootendorst, Diana C; Vogels, Oscar J M; Rijsman, Roselyne M

    2014-08-15

    A variety of sensory stimuli relieve restless legs syndrome symptoms. Because systematic evaluations of sensory stimulation in restless legs syndrome are largely lacking, we performed a randomized crossover study to evaluate the effect of external sensory stimulation on restless legs syndrome symptoms. Eighteen patients underwent 3 consecutive suggestive immobilization tests with the order of the following 3 conditions randomly assigned: no electrical stimulation (condition 1), tactile and proprioceptive sensory stimulation (condition 2), and tactile sensory stimulation only (condition 3). Restless legs syndrome symptoms were quantified by visual analog scales, and periodic leg movements during wake were measured. Baseline visual analogue scale score was 4.5 (range 0-60) in condition 1, 10.5 (range 0-96) in condition 2, and 8.5 in condition 3 (p = 0.21). There was a tendency towards a higher maximum visual analogue scale score and visual analogue scale score at the end of the suggested immobilization test in the conditions with tactile sensory stimulation, though not significant (p = 0.74 and p = 0.29, respectively). Fifteen patients suffered from periodic leg movements during wake. Median indices were 18 (range 0-145) in condition 1, 26 (range 0-190) in condition 2, and 49 (range 0-228) in condition 3 (p = 0.76). We found a tendency towards less leg discomfort in the conditions in which an external sensory input was applied. This potential benefit of sensory stimuli on restless legs syndrome severity merits further investigation as this could open new ways towards a better pathophysiological understanding and non-pharmacological treatments.

  12. Growth restoration in azuki bean and maize seedlings by removal of hypergravity stimuli.

    Science.gov (United States)

    Soga, K; Wakabayashi, K; Kamisaka, S; Hoson, T

    2003-01-01

    Hypergravity stimuli, gravitational acceleration of more than 1 x g, decrease the growth rate of azuki bean epicotyls and maize coleoptiles and mesocotyls by decreasing the cell wall extensibility via an increase in the molecular mass of matrix polysaccharides. An increase in the pH in the apoplastic fluid is hypothesized to be involved in the processes of the increase in the molecular mass of matrix polysaccharides due to hypergravity. However, whether such physiological changes by hypergravity are induced by normal physiological responses or caused by physiological damages have not been elucidated. In the present study, we examined the effects of the removal of hypergravity stimuli on growth and the cell wall properties of azuki bean and maize seedlings to clarify whether the effects of hypergravity stimuli on growth and the cell wall properties are reversible or irreversible. When the seedlings grown under hypergravity conditions at 300 x g for several hours were transferred to 1 x g conditions, the growth rate of azuki bean epicotyls and maize coleoptiles and mesocotyls greatly increased within a few hours. The recovery of growth rate of these organs was accompanied by an immediate increase in the cell wall extensibility, a decrease in the molecular mass of matrix polysaccharides, and an increase in matrix polysaccharide-degrading activities. The apoplastic pH also decreased promptly upon the removal of hypergravity stimuli. These results suggest that plants regulate the growth rate of shoots reversibly in response to hypergravity stimuli by changing the cell wall properties, by which they adapt themselves to different gravity conditions. This study also revealed that changes in growth and the cell wall properties under hypergravity conditions could be recognized as normal physiological responses of plants. In addition, the results suggest that the effects of microgravity on plant growth and cell wall properties should be reversible and could disappear promptly

  13. Exploring combinations of auditory and visual stimuli for gaze-independent brain-computer interfaces.

    Directory of Open Access Journals (Sweden)

    Xingwei An

    Full Text Available For Brain-Computer Interface (BCI systems that are designed for users with severe impairments of the oculomotor system, an appropriate mode of presenting stimuli to the user is crucial. To investigate whether multi-sensory integration can be exploited in the gaze-independent event-related potentials (ERP speller and to enhance BCI performance, we designed a visual-auditory speller. We investigate the possibility to enhance stimulus presentation by combining visual and auditory stimuli within gaze-independent spellers. In this study with N = 15 healthy users, two different ways of combining the two sensory modalities are proposed: simultaneous redundant streams (Combined-Speller and interleaved independent streams (Parallel-Speller. Unimodal stimuli were applied as control conditions. The workload, ERP components, classification accuracy and resulting spelling speed were analyzed for each condition. The Combined-speller showed a lower workload than uni-modal paradigms, without the sacrifice of spelling performance. Besides, shorter latencies, lower amplitudes, as well as a shift of the temporal and spatial distribution of discriminative information were observed for Combined-speller. These results are important and are inspirations for future studies to search the reason for these differences. For the more innovative and demanding Parallel-Speller, where the auditory and visual domains are independent from each other, a proof of concept was obtained: fifteen users could spell online with a mean accuracy of 87.7% (chance level <3% showing a competitive average speed of 1.65 symbols per minute. The fact that it requires only one selection period per symbol makes it a good candidate for a fast communication channel. It brings a new insight into the true multisensory stimuli paradigms. Novel approaches for combining two sensory modalities were designed here, which are valuable for the development of ERP-based BCI paradigms.

  14. Influence of Customer Quality Perception on the Effectiveness of Commercial Stimuli for Electronic Products.

    Science.gov (United States)

    Garrido-Morgado, Álvaro; González-Benito, Óscar; Martos-Partal, Mercedes

    2016-01-01

    Creating and maintaining customer loyalty are strategic requirements for modern business. In the current competitive context, product quality, and brand experience are crucial in building and maintaining customer loyalty. Consumer loyalty, which may be classified into cognitive loyalty and affective loyalty, is related to customers' quality perception. Cue utilization theory distinguishes two dimensions for perceived quality, extrinsic quality-linked to the brand-and intrinsic quality-related with internal product characteristics. We propose that (i) cognitive loyalty is more influenced by intrinsic product quality whereas extrinsic product quality (brand name) is more salient for affective loyalty and, (ii) different commercial stimuli have a differential effectiveness on intrinsic and extrinsic perceived quality. In fact, in this study, we analyze how perceived quality dimensions may influence the effectiveness of two different commercial stimuli: displays and advertising flyers. While displays work within the point of sale under time-constrained conditions where consumers are more likely to use heuristics to simplify their decisions, advertising flyers work outside of the point of sale under low time-constrained conditions, and therefore favor a more reasoned purchase decision where systematic processing will be more likely. We analyze the role of quality perception in determining the effectiveness of both these commercial stimuli for selling products that induce high purchase involvement and perceived risk. The empirical analysis focuses on computer products sold by one of Europe's largest computer retailers and it combines scanner, observational, and survey data. The results show that both dimensions of quality perceptions moderate the influence of displays and advertising flyers on sales, but their impact is different on each commercial stimuli. Extrinsic quality perception increases to a greater extent the effect of displays due to the use of a brand name

  15. Influence of customer quality perception on the effectiveness of commercial stimuli for electronic products

    Directory of Open Access Journals (Sweden)

    Álvaro eGarrido-Morgado

    2016-03-01

    Full Text Available Creating and maintaining customer loyalty are strategic requirements for modern business. In the current competitive context, product quality and brand experience are crucial in building and maintaining customer loyalty. Consumer loyalty, which may be classified into cognitive loyalty and affective loyalty, is related to customers’ quality perception. Cue utilization theory distinguishes two dimensions for perceived quality, extrinsic quality –linked to the brand– and intrinsic quality –related with internal product characteristics. We propose that (i cognitive loyalty is more influenced by intrinsic product quality whereas extrinsic product quality (brand name is more salient for affective loyalty and, (ii different commercial stimuli have a differential effectiveness on intrinsic and extrinsic perceived quality. In fact, in this study, we analyze how perceived quality dimensions may influence the effectiveness of two different commercial stimuli: displays and advertising flyers. While displays work within the point of sale under time-constrained conditions where consumers are more likely to use heuristics to simplify their decisions, advertising flyers work outside of the point of sale under low time-constrained conditions, and therefore favor a more reasoned purchase decision where systematic processing will be more likely. We analyze the role of quality perception in determining the effectiveness of both these commercial stimuli for selling products that induce high purchase involvement and perceived risk. The empirical analysis focuses on computer products sold by one of Europe’s largest computer retailers and it combines scanner, observational, and survey data. The results show that both dimensions of quality perceptions moderate the influence of displays and advertising flyers on sales, but their impact is different on each commercial stimuli. Extrinsic quality perception increases to a greater extent the effect of displays due

  16. Influence of Customer Quality Perception on the Effectiveness of Commercial Stimuli for Electronic Products

    Science.gov (United States)

    Garrido-Morgado, Álvaro; González-Benito, Óscar; Martos-Partal, Mercedes

    2016-01-01

    Creating and maintaining customer loyalty are strategic requirements for modern business. In the current competitive context, product quality, and brand experience are crucial in building and maintaining customer loyalty. Consumer loyalty, which may be classified into cognitive loyalty and affective loyalty, is related to customers' quality perception. Cue utilization theory distinguishes two dimensions for perceived quality, extrinsic quality—linked to the brand—and intrinsic quality—related with internal product characteristics. We propose that (i) cognitive loyalty is more influenced by intrinsic product quality whereas extrinsic product quality (brand name) is more salient for affective loyalty and, (ii) different commercial stimuli have a differential effectiveness on intrinsic and extrinsic perceived quality. In fact, in this study, we analyze how perceived quality dimensions may influence the effectiveness of two different commercial stimuli: displays and advertising flyers. While displays work within the point of sale under time-constrained conditions where consumers are more likely to use heuristics to simplify their decisions, advertising flyers work outside of the point of sale under low time-constrained conditions, and therefore favor a more reasoned purchase decision where systematic processing will be more likely. We analyze the role of quality perception in determining the effectiveness of both these commercial stimuli for selling products that induce high purchase involvement and perceived risk. The empirical analysis focuses on computer products sold by one of Europe's largest computer retailers and it combines scanner, observational, and survey data. The results show that both dimensions of quality perceptions moderate the influence of displays and advertising flyers on sales, but their impact is different on each commercial stimuli. Extrinsic quality perception increases to a greater extent the effect of displays due to the use of a brand

  17. Cellulose conjugated FITC-labelled mesoporous silica nanoparticles: intracellular accumulation and stimuli responsive doxorubicin release

    Science.gov (United States)

    Hakeem, Abdul; Zahid, Fouzia; Duan, Ruixue; Asif, Muhammad; Zhang, Tianchi; Zhang, Zhenyu; Cheng, Yong; Lou, Xiaoding; Xia, Fan

    2016-02-01

    Herein, we design novel cellulose conjugated mesoporous silica nanoparticle (CLS-MSP) based nanotherapeutics for stimuli responsive intracellular doxorubicin (DOX) delivery. DOX molecules are entrapped in pores of the fabricated mesoporous silica nanoparticles (MSPs) while cellulose is used as an encapsulating material through esterification on the outlet of the pores of the MSPs to avoid premature DOX release under physiological conditions. In in vitro studies, stimuli responsive DOX release is successfully achieved from DOX loaded cellulose conjugated mesoporous silica nanoparticles (DOX/CLS-MSPs) by pH and cellulase triggers. Intracellular accumulation of DOX/CLS-MSPs in human liver cancer cells (HepG2 cells) is investigated through confocal microscope magnification. Cell viability of HepG2 cells is determined as the percentage of the cells incubated with DOX/CLS-MSPs compared with that of non-incubated cells through an MTT assay.Herein, we design novel cellulose conjugated mesoporous silica nanoparticle (CLS-MSP) based nanotherapeutics for stimuli responsive intracellular doxorubicin (DOX) delivery. DOX molecules are entrapped in pores of the fabricated mesoporous silica nanoparticles (MSPs) while cellulose is used as an encapsulating material through esterification on the outlet of the pores of the MSPs to avoid premature DOX release under physiological conditions. In in vitro studies, stimuli responsive DOX release is successfully achieved from DOX loaded cellulose conjugated mesoporous silica nanoparticles (DOX/CLS-MSPs) by pH and cellulase triggers. Intracellular accumulation of DOX/CLS-MSPs in human liver cancer cells (HepG2 cells) is investigated through confocal microscope magnification. Cell viability of HepG2 cells is determined as the percentage of the cells incubated with DOX/CLS-MSPs compared with that of non-incubated cells through an MTT assay. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr08753h

  18. Category Variability Effect in Category Learning with Auditory Stimuli

    Directory of Open Access Journals (Sweden)

    Lee-Xieng eYang

    2014-10-01

    Full Text Available The category variability effect refers to that people tend to classify the midpoint item between two categories as the category more variable. This effect is regarded as evidence against the exemplar model, such as GCM (Generalized Context Model and favoring the rule model, such as GRT (i.e., the decision bound model. Although this effect has been found in conceptual category learning, it is not often observed in perceptual category learning. To figure out why the category variability effect is seldom reported in the past studies, we propose two hypotheses. First, due to sequence effect, the midpoint item would be classified as different categories, when following different items. When we combine these inconsistent responses for the midpoint item, no category variability effect occurs. Second, instead of the combination of sequence effect in different categorization conditions, the combination of different categorization strategies conceals the category variability effect. One experiment is conducted with single tones of different frequencies as stimuli. The collected data reveal sequence effect. However, the modeling results with the MAC model and the decision bound model support that the existence of individual differences is the reason for why no category variability effect occurs. Three groups are identified by their categorization strategy. Group 1 is rule user, placing the category boundary close to the low-variability category, hence inducing category variability effect. Group 2 takes the MAC strategy and classifies the midpoint item as different categories, depending on its preceding item. Group 3 classifies the midpoint item as the low-variability category, which is consistent with the prediction of the decision bound model as well as GCM. Nonetheless, our conclusion is that category variability effect can be found in perceptual category learning, but might be concealed by the averaged data.

  19. Go/No-Go Procedure with Compound Stimuli: Effects of Training Structure on the Emergence of Equivalence Classes

    Science.gov (United States)

    Grisante, Priscila C.; Galesi, Fernanda L.; Sabino, Nathali M.; Debert, Paula; Arntzen, Erik; McIlvane, William J.

    2013-01-01

    When the matching-to-sample (MTS) procedure is used, different training structures imply differences in the successive discriminations required in training and test conditions. When the go/no-go procedure with compound stimuli is used, however, differences in training structures do not imply such differences. This study assessed whether the…

  20. Differential role of muscarinic transmission within the entorhinal cortex and basolateral amygdala in the processing of irrelevant stimuli.

    Science.gov (United States)

    Barak, Segev; Weiner, Ina

    2010-04-01

    Cholinergic projections to the entorhinal cortex (EC) and basolateral amygdala (BLA) mediate distinct cognitive processes through muscarinic acetylcholine receptors (mAChRs). In this study, we sought to further differentiate the role of muscarinic transmission in these regions in cognition, using the latent inhibition (LI) phenomenon. LI is a cross-species phenomenon manifested as poorer conditioning to a stimulus experienced as irrelevant during an earlier stage of repeated non-reinforced pre-exposure to that stimulus, and is considered to index the ability to ignore, or to in-attend to, irrelevant stimuli. Given our recent findings that systemic administration of the mAChR antagonist scopolamine can produce two contrasting LI abnormalities in rats, ie, abolish LI under conditions yielding LI in non-treated controls, or produce abnormally persistent LI under conditions preventing its expression in non-treated controls, we tested whether mAChR blockade in the EC and BLA would induce LI abolition and persistence, respectively. We found that intra-EC scopolamine infusion (1, 10 mug per hemisphere) abolished LI when infused in pre-exposure or both pre-exposure and conditioning, but not in conditioning alone, whereas intra-BLA scopolamine infusion led to persistent LI when infused in conditioning or both stages, but not in pre-exposure alone. Although cholinergic innervation of the EC and BLA has long been implicated in attention to novel stimuli and in processing of motivationally significant stimuli, respectively, our results provide evidence that EC mAChRs also have a role in the development of inattention to stimuli, whereas BLA mAChRs have a role in re-attending to previously irrelevant stimuli that became motivationally relevant.

  1. Spatial coherence does not affect contrast discrimination for multiple Gabor stimuli.

    Science.gov (United States)

    Meese, T S; Hess, R F; Williams, C B

    2001-01-01

    Gestalt grouping rules imply a process or mechanism for grouping together local features of an object into a perceptual whole. Several psychophysical experiments have been interpreted as evidence for constrained interactions between nearby spatial filter elements and this has led to the hypothesis that element linking might be mediated by these interactions. A common tacit assumption is that these interactions result in response modulation which disturbs a local contrast code. We addressed this possibility by performing contrast discrimination experiments using two-dimensional arrays of multiple Gabor patches arranged either (i) vertically, (ii) in circles (coherent conditions), or (iii) randomly (incoherent condition), as well as for a single Gabor patch. In each condition, contrast increments were applied to either the entire test stimulus (experiment 1) or a single patch whose position was cued (experiment 2). In experiment 3, the texture stimuli were reduced to a single contour by displaying only the central vertical strip. Performance was better for the multiple-patch conditions than for the single-patch condition, but whether the multiple-patch stimulus was coherent or not had no systematic effect on the results in any of the experiments. We conclude that constrained local interactions do not interfere with a local contrast code for our suprathreshold stimuli, suggesting that, in general, this is not the way in which element linking is achieved. The possibility that interactions are involved in enhancing the detectability of contour elements at threshold remains unchallenged by our experiments.

  2. 双车道公路设置附加车道交通量条件研究%Traffic Volume Conditions of Setting Auxiliary Lane on Two-lane Highway

    Institute of Scientific and Technical Information of China (English)

    程国柱; 翟露露; 秦丽辉; 王玉霞

    2015-01-01

    In order to reduce traffic accidents and improve operating efficiency on two-lane highway, the concept of setting auxiliary lane on two-lane highway is proposed, and the traffic volume conditions of setting up auxiliary lane on two-lane highway are studied. Data is obtained through vehicle experiment on two-lane highway, and the relational model among the traffic conflict time, the traffic volume and the design speed on two-lane highway is established. Based on the established model, the different conditions of traffic volume of setting auxiliary lane on two-lane highway are obtained. It shows that auxiliary lane should be set when traffic volume is more than 495 veh/h/ln and 454 veh/h/ln respectively on two-lane highway with the design speed of 80 km/h and 60km/h. It isn't recommend to set auxiliary lane on two-lane highway with the design speed of 40 km/h because the benefit is not obvious.%为了减少双车道公路交通事故数量、提高运行效率,提出了双车道公路设置附加车道的理念,基于试验数据开展了双车道公路设置附加车道的交通量条件研究.通过双车道公路实车实验获得的基础数据,建立了双车道公路交通冲突时间与交通量、设计速度的关系模型.依据构建的模型,给出了对应不同设计速度的双车道公路设置附加车道的交通量条件.基于样本数据的研究结果表明:设计速度为80 km/h的双车道公路,单向交通量大于495 veh/h/ln时,应设置附加车道;设计速度为60 km/h的双车道公路,单向交通量大于454 veh/h/ln,应设置附加车道;设计速度为40 km/h及以下的双车道公路,设置附加车道效益不明显,不建议设置.

  3. Behavioral detection of passive whisker stimuli requires somatosensory cortex.

    Science.gov (United States)

    Miyashita, Toshio; Feldman, Daniel E

    2013-07-01

    Rodent whisker sensation occurs both actively, as whiskers move rhythmically across objects, and in a passive mode in which externally applied deflections are sensed by static, non-moving whiskers. Passive whisker stimuli are robustly encoded in the somatosensory (S1) cortex, and provide a potentially powerful means of studying cortical processing. However, whether S1 contributes to passive sensation is debated. We developed 2 new behavioral tasks to assay passive whisker sensation in freely moving rats: Detection of unilateral whisker deflections and discrimination of right versus left whisker deflections. Stimuli were simple, simultaneous multi-whisker deflections. Local muscimol inactivation of S1 reversibly and robustly abolished sensory performance on these tasks. Thus, S1 is required for the detection and discrimination of simple stimuli by passive whiskers, in addition to its known role in active whisker sensation.

  4. Attentional capture by social stimuli in young infants

    Directory of Open Access Journals (Sweden)

    Maxie eGluckman

    2013-08-01

    Full Text Available We investigated the possibility that a range of social stimuli capture the attention of 6-month-old infants when in competition with other non-face objects. Infants viewed a series of six-item arrays in which one target item was a face, body part, or animal as their eye movements were recorded. Stimulus arrays were also processed for relative salience of each item in terms of color, luminance, and amount of contour. Targets were rarely the most visually salient items in the arrays, yet infants’ first looks toward all three target types were above chance, and dwell times for targets exceeded other stimulus types. Girls looked longer at faces than did boys, but there were no sex differences for other stimuli. These results are interpreted in a context of learning to discriminate between different classes of animate stimuli, perhaps in line with affordances for social interaction, and origins of sex differences in social attention.

  5. Pedophilic brain potential responses to adult erotic stimuli.

    Science.gov (United States)

    Knott, Verner; Impey, Danielle; Fisher, Derek; Delpero, Emily; Fedoroff, Paul

    2016-02-01

    Cognitive mechanisms associated with the relative lack of sexual interest in adults by pedophiles are poorly understood and may benefit from investigations examining how the brain processes adult erotic stimuli. The current study used event-related brain potentials (ERP) to investigate the time course of the explicit processing of erotic, emotional, and neutral pictures in 22 pedophilic patients and 22 healthy controls. Consistent with previous studies, early latency anterior ERP components were highly selective for erotic pictures. Although the ERPs elicited by emotional stimuli were similar in patients and controls, an early frontal positive (P2) component starting as early as 185 ms was significantly attenuated and slow to onset in pedophilia, and correlated with a clinical measure of cognitive distortions. Failure of rapid attentional capture by erotic stimuli suggests a relative reduction in early processing in pedophilic patients which may be associated with relatively diminished sexual interest in adults.

  6. Generating stimuli for neuroscience using PsychoPy

    Directory of Open Access Journals (Sweden)

    Jonathan W Peirce

    2009-01-01

    Full Text Available PsychoPy is a software library written in Python, using OpenGL to generate very precise visual stimuli on standard personal computers. It is designed to allow the construction of as wide a variety of neuroscience experiments as possible, with the least effort. By writing scripts in standard Python syntax users can generate an enormous variety of visual and auditory stimuli and can interact with a wide range of external hardware (enabling its use in fMRI, EEG, MEG etc.. The structure of scripts is simple and intuitive. As a result, new experiments can be written very quickly, and trying to understand a previously written script is easy, even with minimal code comments. PsychoPy can also generate movies and image sequences to be used in demos or simulated neuroscience experiments. This paper describes the range of tools and stimuli that it provides and the environment in which experiments are conducted.

  7. Generating Stimuli for Neuroscience Using PsychoPy.

    Science.gov (United States)

    Peirce, Jonathan W

    2008-01-01

    PsychoPy is a software library written in Python, using OpenGL to generate very precise visual stimuli on standard personal computers. It is designed to allow the construction of as wide a variety of neuroscience experiments as possible, with the least effort. By writing scripts in standard Python syntax users can generate an enormous variety of visual and auditory stimuli and can interact with a wide range of external hardware (enabling its use in fMRI, EEG, MEG etc.). The structure of scripts is simple and intuitive. As a result, new experiments can be written very quickly, and trying to understand a previously written script is easy, even with minimal code comments. PsychoPy can also generate movies and image sequences to be used in demos or simulated neuroscience experiments. This paper describes the range of tools and stimuli that it provides and the environment in which experiments are conducted.

  8. Diffusion Based Modeling of Human Brain Response to External Stimuli

    CERN Document Server

    Namazi, Hamidreza

    2012-01-01

    Human brain response is the overall ability of the brain in analyzing internal and external stimuli in the form of transferred energy to the mind/brain phase-space and thus, making the proper decisions. During the last decade scientists discovered about this phenomenon and proposed some models based on computational, biological, or neuropsychological methods. Despite some advances in studies related to this area of the brain research there was less effort which have been done on the mathematical modeling of the human brain response to external stimuli. This research is devoted to the modeling of human EEG signal, as an alert state of overall human brain activity monitoring, due to receiving external stimuli, based on fractional diffusion equation. The results of this modeling show very good agreement with the real human EEG signal and thus, this model can be used as a strong representative of the human brain activity.

  9. Advances in Application of Mechanical Stimuli in Bioreactors for Cartilage Tissue Engineering.

    Science.gov (United States)

    Li, Ke; Zhang, Chunqiu; Qiu, Lulu; Gao, Lilan; Zhang, Xizheng

    2017-08-01

    Articular cartilage (AC) is the weight-bearing tissue in diarthroses. It lacks the capacity for self-healing once there are injuries or diseases due to its avascularity. With the development of tissue engineering, repairing cartilage defects through transplantation of engineered cartilage that closely matches properties of native cartilage has become a new option for curing cartilage diseases. The main hurdle for clinical application of engineered cartilage is how to develop functional cartilage constructs for mass production in a credible way. Recently, impressive hyaline cartilage that may have the potential to provide capabilities for treating large cartilage lesions in the future has been produced in laboratories. The key to functional cartilage construction in vitro is to identify appropriate mechanical stimuli. First, they should ensure the function of metabolism because mechanical stimuli play the role of blood vessels in the metabolism of AC, for example, acquiring nutrition and removing wastes. Second, they should mimic the movement of synovial joints and produce phenotypically correct tissues to achieve the adaptive development between the micro- and macrostructure and function. In this article, we divide mechanical stimuli into three types according to forces transmitted by different media in bioreactors, namely forces transmitted through the liquid medium, solid medium, or other media, then we review and summarize the research status of bioreactors for cartilage tissue engineering (CTE), mainly focusing on the effects of diverse mechanical stimuli on engineered cartilage. Based on current researches, there are several motion patterns in knee joints; but compression, tension, shear, fluid shear, or hydrostatic pressure each only partially reflects the mechanical condition in vivo. In this study, we propose that rolling-sliding-compression load consists of various stimuli that will represent better mechanical environment in CTE. In addition, engineers

  10. Electrotactile stimuli delivered across fingertips inducing the Cutaneous Rabbit Effect.

    Science.gov (United States)

    Warren, Jay P; Santello, Marco; Helms Tillery, Stephen I

    2010-10-01

    Previous studies have been unable to induce the Cutaneous Rabbit Effect (CRE) when the most likely perceived location of the illusory stimulus is on a non-continuous skin area. To determine whether the CRE could be elicited when each of the delivered stimuli were on non-continuous skin areas, we developed a new electrotactile stimulation paradigm attempting to induce the CRE across the fingertips. Though our stimulation paradigm differed from classic reduced CRE paradigms through the use of electrotactile stimuli, focusing the subject attention to a 'likely' illusory site, and the inclusion of a fourth stimulation site (two stimuli after the illusory stimulus), these factors were not the cause of the illusory effect we observed. Experiments conducted on the forearm validated that our paradigm elicited similar results to those reported in previous CRE studies that used either 3-stimulation-point mechanical or electrotactile stimuli with subject attention focused on the 'likely' illusory site. Across the fingertips, we observed an increase in stimulus mislocalization onto the middle fingertip, the 'likely' perceived location of the illusory stimuli, under Illusory Rabbit Trains compared to the Motion Bias Trains. Because the Motion Bias Trains should not induce a perceived location shift of the illusory stimulus but stimulates the adjacent digits in a similar way to the Illusory Rabbit Trains, differences observed between their mislocalization rates between these trains indicate that the CRE can be induced across the fingertips. These results provide the first evidence that the CRE can 'jump' when the stimuli occur across non-continuous skin areas.

  11. A comparison of vernier acuity for narrowband and broadband stimuli.

    Science.gov (United States)

    Barrett, Brendan T; Whitaker, David

    2004-01-01

    This study investigates the influence of contrast and exposure duration on vernier acuity thresholds for abutting and separated narrowband stimuli, and asks whether these data can predict broadband vernier performance. Vernier thresholds were determined for sinusoidal grating stimuli at two spatial frequencies (1 and 8 c/deg) across a range of contrasts (0.05-0.8) and exposure durations (35-2100 ms). Performance was assessed for the abutting configuration, and when a gap equivalent to 0.5 to 1.5 times the spatial period of the grating was introduced between the upper and lower halves of the grating. Vernier thresholds were also determined for a square-wave stimulus as a function of contrast (0.06 to 0.78). Exposure duration was fixed at 2100 ms. In addition, thresholds were determined at the appropriate contrast levels for the fundamental frequency (1.8 c/deg) of the square-wave, and for a number of the harmonics (3F, 5F, 7F, 9F). Our results provide support for filter models of vernier acuity by showing that vernier performance for abutting and closely-separated broadband stimuli represents the envelope of vernier sensitivity of those spatial frequency mechanisms that are activated by the broadband stimulus. In the case of high frequency grating stimuli presented for long exposure durations, vernier performance can be invariant across much of the contrast range. Despite this, however, contrast independence is not exhibited for abutting broadband stimuli because, within the broadband stimuli, the contrast of the higher harmonic components never reaches a level to reveal this plateau.

  12. Joint attention for stimuli on the hands: Ownership matters

    OpenAIRE

    Eric eTaylor; Jay ePratt; Jessica eWitt

    2015-01-01

    The visual system treats the space near the hands with unique, action-related priorities. For example, attention orients slowly to stimuli on the hands (Taylor and Witt, 2014). In this article, we asked whether jointly attended hands are attended in the same way. Specifically, we examined whether ownership over the hand mattered: do we attend to our hands and the hands of others in the same way? Pairs of participants performed a spatial cueing task with stimuli that could be projected onto on...

  13. Precuneus-prefrontal activity during awareness of visual verbal stimuli

    DEFF Research Database (Denmark)

    Kjaer, T W; Nowak, M; Kjær, Klaus Wilbrandt

    2001-01-01

    Awareness is a personal experience, which is only accessible to the rest of world through interpretation. We set out to identify a neural correlate of visual awareness, using brief subliminal and supraliminal verbal stimuli while measuring cerebral blood flow distribution with H(2)(15)O PET....... Awareness of visual verbal stimuli differentially activated medial parietal association cortex (precuneus), which is a polymodal sensory cortex, and dorsolateral prefrontal cortex, which is thought to be primarily executive. Our results suggest participation of these higher order perceptual and executive...... cortical structures in visual verbal awareness....

  14. Advantage of dichromats over trichromats in discrimination of color-camouflaged stimuli in nonhuman primates.

    Science.gov (United States)

    Saito, Atsuko; Mikami, Akichika; Kawamura, Shoji; Ueno, Yoshikazu; Hiramatsu, Chihiro; Widayati, Kanthi A; Suryobroto, Bambang; Teramoto, Migaku; Mori, Yusuke; Nagano, Kunitoshi; Fujita, Kazuo; Kuroshima, Hika; Hasegawa, Toshikazu

    2005-12-01

    Due to a middle- to long-wavelength-sensitive (M/LWS) cone opsin polymorphism, there is considerable phenotypic variation in the color vision of New World monkeys. Many females have trichromatic vision, whereas some females and all males have dichromatic vision. The selective pressures that maintain this polymorphism are unclear. In the present study we compared the performance of dichromats and trichromats in a discrimination task. We examined tri- and dichromatic individuals of two species: brown capuchin monkeys (Cebus apella) and long-tailed macaques (Macaca fascicularis). We also examined one protanomalous chimpanzee (Pan troglodytes). The subjects' task was to discriminate a circular pattern from other patterns in which textural elements differed in orientation and thickness from the background. After they were trained with stimuli of a single color, the subjects were presented with color-camouflaged stimuli with a green/red mosaic overlaid onto the pattern. The dichromatic monkeys and the protanomalous chimpanzee selected the correct stimulus under camouflaged conditions at rates significantly above chance levels, while the trichromats did not. These findings demonstrate that dichromatic nonhuman primates possess a superior visual ability to discriminate color-camouflaged stimuli, and that such an ability may confer selective advantages with respect to the detection of cryptic foods and/or predators.

  15. Ultra-bright and stimuli-responsive fluorescent nanoparticles for bioimaging.

    Science.gov (United States)

    Battistelli, Giulia; Cantelli, Andrea; Guidetti, Gloria; Manzi, Jeannette; Montalti, Marco

    2016-01-01

    Fluorescent nanoparticles (NPs) are unique contrast agents for bioimaging. Examples of molecular-based fluorescent NPs with brightness similar or superior to semiconductor quantum dots have been reported. These ultra-bright NPs consist of a silica or polymeric matrix that incorporate the emitting dyes as individual moieties or aggregates and promise to be more biocompatible than semiconductor quantum dots. Ultra-bright materials result from heavy doping of the structural matrix, a condition that entails a close mutual proximity of the doping dyes. Ground state and excited state interactions between the molecular emitters yield aggregation-caused quenching (ACQ) and proximity-caused quenching (PCQ). In combination with Föster resonance energy transfer (FRET) ACQ and PCQ originate collective phenomena that produce amplified quenching of the nanoprobes. In this focus article, we discuss strategies to achieve ultra-bright nanoprobes avoiding ACQ and PCQ also exploiting aggregation-induced emission (AIE). Amplified quenching, on the other hand, is also proposed as a strategy to design stimuli-responsive fluorogenic probes through disaggregation-induced emission (DIE) in alternative to AIE. As an advantage, DIE consents to design stimuli-responsive materials starting from a large variety of precursors. On the contrary, AIE is characteristic of a limited number of species. Examples of stimuli-responsive fluorogenic probes based on DIE are discussed.

  16. Muscle group dependent responses to stimuli in a grasshopper model for tonic immobility

    Directory of Open Access Journals (Sweden)

    Ashwin Miriyala

    2013-09-01

    Tonic Immobility (TI is a prolonged immobile condition exhibited by a variety of animals when exposed to certain stimuli, and is thought to be associated with a specific state of arousal. In our study, we characterize this state by using the reliably inducible TI state of the grasshopper (Hieroglyphus banian and by monitoring abdominal pulsations and body movements in response to visual and auditory stimuli. These pulsations are present during the TI and ‘awake’, standing states, but not in the CO2 anesthetized state. In response to the stimuli, animals exhibited a suppression in pulsation and a startle response. The suppression of pulsation lasted longer than the duration of stimulus application. During TI, the suppression of pulsation does not habituate over time, whereas the startle response does. In response to the translating visual stimulus, the pulsations are suppressed at a certain phase independent of the time of stimulus application. Thus, we describe TI in Hieroglyphus banian as a state more similar to an ‘awake’ state than to an anesthetized state. During TI, the circuitry to the muscle outputs controlling the abdomen pulsation and the startle response are, at least in some part, different. The central pattern generators that maintain the abdomen pulsation receive inputs from visual and auditory pathways.

  17. Information transmission for one-dimensional stimuli: the role of strategies.

    Science.gov (United States)

    De Sanctis, Pierfilippo; Sommer, Werner

    2009-05-01

    Important evidence about the information flow between perceptual and motor processes has been obtained from the lateralized readiness potential (LRP) recorded in two-choice go/nogo tasks. Here, we investigated the effect of time pressure on information transmission for one-dimensional stimuli (four squares differing in size). In between- and within-subject designs, respectively, Experiments 1 and 2 showed that under time pressure partial information initiates hand decision and response preparation before complete size information is available. These findings appear to be at odds with the asynchronous discrete coding model. Experiment 3 assessed the mechanisms behind these effects by manipulating the relative difficulty of extracting hand- and go/nogo-specific information from the size of the stimuli. Consistent with asynchronous coding, our results suggest that serial-consecutive processes in extracting partial and full size information may occur also for one-dimensional stimuli. Our data are inconclusive as to the question of discreteness or continuity of information transmission. On a more general level, our data support the notion of flexibility in the coding of perceptual dimensions to adapt performance to environmental conditions.

  18. Classical conditioning and pain: conditioned analgesia and hyperalgesia.

    Science.gov (United States)

    Miguez, Gonzalo; Laborda, Mario A; Miller, Ralph R

    2014-01-01

    This article reviews situations in which stimuli produce an increase or a decrease in nociceptive responses through basic associative processes and provides an associative account of such changes. Specifically, the literature suggests that cues associated with stress can produce conditioned analgesia or conditioned hyperalgesia, depending on the properties of the conditioned stimulus (e.g., contextual cues and audiovisual cues vs. gustatory and olfactory cues, respectively) and the proprieties of the unconditioned stimulus (e.g., appetitive, aversive, or analgesic, respectively). When such cues are associated with reducers of exogenous pain (e.g., opiates), they typically increase sensitivity to pain. Overall, the evidence concerning conditioned stress-induced analgesia, conditioned hyperalagesia, conditioned tolerance to morphine, and conditioned reduction of morphine analgesia suggests that selective associations between stimuli underlie changes in pain sensitivity.

  19. CLASSICAL CONDITIONING AND PAIN: CONDITIONED ANALGESIA AND HYPERALGESIA

    Science.gov (United States)

    Miguez, Gonzalo; Laborda, Mario A.; Miller, Ralph R.

    2013-01-01

    This article reviews situations in which stimuli produce an increase or a decrease in nociceptive responses through basic associative processes and provides an associative account of such changes. Specifically, the literature suggests that cues associated with stress can produce conditioned analgesia or conditioned hyperalgesia, depending on the properties of the conditioned stimulus (e.g., contextual cues and audiovisual cues vs. gustatory and olfactory cues, respectively) and the proprieties of the unconditioned stimulus (e.g., appetitive, aversive, or analgesic, respectively). When such cues are associated with reducers of exogenous pain (e.g., opiates), they typically increase sensitivity to pain. Overall, the evidence concerning conditioned stress-induced analgesia, conditioned hyperalagesia, conditioned tolerance to morphine, and conditioned reduction of morphine analgesia suggests that selective associations between stimuli underlie changes in pain sensitivity. PMID:24269884

  20. Changing CS Features Alters Evaluative Responses in Evaluative Conditioning

    Science.gov (United States)

    Unkelbach, Christian; Stahl, Christoph; Forderer, Sabine

    2012-01-01

    Evaluative conditioning (EC) refers to changes in people's evaluative responses toward initially neutral stimuli (CSs) by mere spatial and temporal contiguity with other positive or negative stimuli (USs). We investigate whether changing CS features from conditioning to evaluation also changes people's evaluative response toward these CSs. We used…

  1. Exploring space: Effects of environmental stimuli on self-disclosure

    NARCIS (Netherlands)

    Okken, Vanessa Simone

    2013-01-01

    The research in this dissertation examines the effects of environmental stimuli on self-disclosure during interactions in service environments. Earlier explanations of why behavior can be influenced by environmental factors focused on comfort and affect. In this dissertation experienced spaciousness

  2. Submillisecond unmasked subliminal visual stimuli evoke electrical brain responses.

    Science.gov (United States)

    Sperdin, Holger F; Spierer, Lucas; Becker, Robert; Michel, Christoph M; Landis, Theodor

    2015-04-01

    Subliminal perception is strongly associated to the processing of meaningful or emotional information and has mostly been studied using visual masking. In this study, we used high density 256-channel EEG coupled with an liquid crystal display (LCD) tachistoscope to characterize the spatio-temporal dynamics of the brain response to visual checkerboard stimuli (Experiment 1) or blank stimuli (Experiment 2) presented without a mask for 1 ms (visible), 500 µs (partially visible), and 250 µs (subliminal) by applying time-wise, assumption-free nonparametric randomization statistics on the strength and on the topography of high-density scalp-recorded electric field. Stimulus visibility was assessed in a third separate behavioral experiment. Results revealed that unmasked checkerboards presented subliminally for 250 µs evoked weak but detectable visual evoked potential (VEP) responses. When the checkerboards were replaced by blank stimuli, there was no evidence for the presence of an evoked response anymore. Furthermore, the checkerboard VEPs were modulated topographically between 243 and 296 ms post-stimulus onset as a function of stimulus duration, indicative of the engagement of distinct configuration of active brain networks. A distributed electrical source analysis localized this modulation within the right superior parietal lobule near the precuneus. These results show the presence of a brain response to submillisecond unmasked subliminal visual stimuli independently of their emotional saliency or meaningfulness and opens an avenue for new investigations of subliminal stimulation without using visual masking. © 2014 Wiley Periodicals, Inc.

  3. Updating Positive and Negative Stimuli in Working Memory in Depression

    Science.gov (United States)

    Levens, Sara M.; Gotlib, Ian H.

    2010-01-01

    Difficulties in the ability to update stimuli in working memory (WM) may underlie the problems with regulating emotions that lead to the development and perpetuation of mood disorders such as depression. To examine the ability to update affective material in WM, the authors had diagnosed depressed and never-disordered control participants perform…

  4. Processing of Binaural Pitch Stimuli in Hearing-Impaired Listeners

    DEFF Research Database (Denmark)

    Santurette, Sébastien; Dau, Torsten

    2009-01-01

    hearingloss; 3: retro-cochlear impairment) were asked to identify the pitch contour of series of five notes of equal duration, ranging from 523 to 784 Hz, played either with Huggins’ binaural pitch stimuli (BP) or perceptually similar, but monaurally detectable, pitches (MP). All subjects from groups 1 and 2...

  5. Infants' Preferential Attention to Sung and Spoken Stimuli

    Science.gov (United States)

    Costa-Giomi, Eugenia; Ilari, Beatriz

    2014-01-01

    Caregivers and early childhood teachers all over the world use singing and speech to elicit and maintain infants' attention. Research comparing infants' preferential attention to music and speech is inconclusive regarding their responses to these two types of auditory stimuli, with one study showing a music bias and another one…

  6. Stress improves selective attention towards emotionally neutral left ear stimuli.

    Science.gov (United States)

    Hoskin, Robert; Hunter, M D; Woodruff, P W R

    2014-09-01

    Research concerning the impact of psychological stress on visual selective attention has produced mixed results. The current paper describes two experiments which utilise a novel auditory oddball paradigm to test the impact of psychological stress on auditory selective attention. Participants had to report the location of emotionally-neutral auditory stimuli, while ignoring task-irrelevant changes in their content. The results of the first experiment, in which speech stimuli were presented, suggested that stress improves the ability to selectively attend to left, but not right ear stimuli. When this experiment was repeated using tonal stimuli the same result was evident, but only for female participants. Females were also found to experience greater levels of distraction in general across the two experiments. These findings support the goal-shielding theory which suggests that stress improves selective attention by reducing the attentional resources available to process task-irrelevant information. The study also demonstrates, for the first time, that this goal-shielding effect extends to auditory perception.

  7. Differences in Sensorimotor Processing of Visual and Proprioceptive Stimuli

    Science.gov (United States)

    Kamen, Gary and Morris, Harold H.

    1988-01-01

    A paradox in studying sensory perception is that people often attend to a stimulus which provides the least optimal information. Usually, this is a visual stimulus. The study sought to lessen this reliance on vision by training subjects to respond to proprioceptive stimuli. Results are discussed. (Author/JL)

  8. Lateralization of Components of Melodic Stimuli: Musicians versus Nonmusicians.

    Science.gov (United States)

    Baumagarte, Roger; Franklin, Elda

    1981-01-01

    Using dichotic listening methodology, 25 musicians and 25 nonmusicians were compared on four cerebral lateralization tasks: melodies, tonal patterns, rhythm patterns, and verbal stimuli. Musicians demonstrated superior performance on the music tasks. Results are interpreted in terms of superior cognitive strategies of musicians as a function of…

  9. Functionalized mesoporous silica nanoparticles for stimuli-responsive and targeted

    Energy Technology Data Exchange (ETDEWEB)

    Knezevic, Nikola [Iowa State Univ., Ames, IA (United States)

    2009-12-15

    Construction of functional supramolecular nanoassemblies has attracted great deal of attention in recent years for their wide spectrum of practical applications. Mesoporous silica nanoparticles (MSN) in particular were shown to be effective scaffolds for the construction of drug carriers, sensors and catalysts. Herein, we describe the synthesis and characterization of stimuli-responsive, controlled release MSN-based assemblies for drug delivery.

  10. Impact prediction by looming visual stimuli enhances tactile detection.

    Science.gov (United States)

    Cléry, Justine; Guipponi, Olivier; Odouard, Soline; Wardak, Claire; Ben Hamed, Suliann

    2015-03-11

    From an ecological point of view, approaching objects are potentially more harmful than receding objects. A predator, a dominant conspecific, or a mere branch coming up at high speed can all be dangerous if one does not detect them and produce the appropriate escape behavior fast enough. And indeed, looming stimuli trigger stereotyped defensive responses in both monkeys and human infants. However, while the heteromodal somatosensory consequences of visual looming stimuli can be fully predicted by their spatiotemporal dynamics, few studies if any have explored whether visual stimuli looming toward the face predictively enhance heteromodal tactile sensitivity around the expected time of impact and at its expected location on the body. In the present study, we report that, in addition to triggering a defensive motor repertoire, looming stimuli toward the face provide the nervous system with predictive cues that enhance tactile sensitivity on the face. Specifically, we describe an enhancement of tactile processes at the expected time and location of impact of the stimulus on the face. We additionally show that a looming stimulus that brushes past the face also enhances tactile sensitivity on the nearby cheek, suggesting that the space close to the face is incorporated into the subjects' body schema. We propose that this cross-modal predictive facilitation involves multisensory convergence areas subserving the representation of a peripersonal space and a safety boundary of self.

  11. Relative finger position influences whether you can localize tactile stimuli

    NARCIS (Netherlands)

    Overvliet, K.E.; Anema, H.A.; Brenner, E.; Dijkerman, H.C.; Smeets, J.B.J.

    2011-01-01

    To investigate whether the relative positions of the fingers influence tactile localization, participants were asked to localize tactile stimuli applied to their fingertips. We measured the location and rate of errors for three finger configurations: fingers stretched out and together so that they a

  12. Lateralization of Components of Melodic Stimuli: Musicians versus Nonmusicians.

    Science.gov (United States)

    Baumagarte, Roger; Franklin, Elda

    1981-01-01

    Using dichotic listening methodology, 25 musicians and 25 nonmusicians were compared on four cerebral lateralization tasks: melodies, tonal patterns, rhythm patterns, and verbal stimuli. Musicians demonstrated superior performance on the music tasks. Results are interpreted in terms of superior cognitive strategies of musicians as a function of…

  13. Localization of monocular stimuli in different depth planes.

    Science.gov (United States)

    Shimono, Koichi; Tam, Wa James; Asakura, Nobuhiko; Ohmi, Masao

    2005-09-01

    We examined the phenomenon in which two physically aligned monocular stimuli appear to be non-collinear when each of them is located in binocular regions that are at different depth planes. Using monocular bars embedded in binocular random-dot areas that are at different depths, we manipulated properties of the binocular areas and examined their effect on the perceived direction and depth of the monocular stimuli. Results showed that (1) the relative visual direction and perceived depth of the monocular bars depended on the binocular disparity and the dot density of the binocular areas, and (2) the visual direction, but not the depth, depended on the width of the binocular regions. These results are consistent with the hypothesis that monocular stimuli are treated by the visual system as binocular stimuli that have acquired the properties of their binocular surrounds. Moreover, partial correlation analysis suggests that the visual system utilizes both the disparity information of the binocular areas and the perceived depth of the monocular bars in determining the relative visual direction of the bars.

  14. Positive erotic picture stimuli for emotion research in heterosexual females.

    Science.gov (United States)

    Jacob, Gitta Anne; Arntz, Arnoud; Domes, Gregor; Reiss, Neele; Siep, Nicolette

    2011-12-30

    In most experimental studies, emotional pictures are widely used as stimulus material. However, there is still a lack of standardization of picture stimuli displaying erotic relationships, despite the association between a number of psychological problems and severe impairments and problems in intimate relationships. The aim of the study was to test a set of erotic stimuli, with the potential to be used in experimental studies, with heterosexual female subjects. Twenty International Affective Picture System (IAPS) pictures and an additional 100 pictures showing romantic but not explicitly sexual scenes and/or attractive single males were selected. All pictures were rated with respect to valence, arousal, and dominance by 41 heterosexual women and compared to pictures with negative, positive, and neutral emotional valence. Erotic IAPS pictures and our additional erotic pictures did not differ in any of the evaluation dimensions. Analyses of variance (ANOVAs) for valence, arousal, and dominance comparing different picture valence categories showed strong effects for category. However, valence was not significantly different between erotic and positive pictures, while arousal and control were not significantly different between positive and neutral pictures. The pictures of our new set are as positive for heterosexual women as highly positive IAPS pictures, but higher in arousal and dominance. The picture set can be used in experimental psychiatric studies requiring high numbers of stimuli per category. Limitations are the restriction of stimuli application to heterosexual females only and to self-report data. Copyright © 2011 Elsevier Ltd. All rights reserved.

  15. Exploring space: Effects of environmental stimuli on self-disclosure

    NARCIS (Netherlands)

    Okken, V.S.

    2013-01-01

    The research in this dissertation examines the effects of environmental stimuli on self-disclosure during interactions in service environments. Earlier explanations of why behavior can be influenced by environmental factors focused on comfort and affect. In this dissertation experienced spaciousness

  16. Multi stimuli-responsive hydrogel microfibers containing magnetite nanoparticles prepared using microcapillary devices.

    Science.gov (United States)

    Lim, Daeun; Lee, Eunsu; Kim, Haneul; Park, Sungmin; Baek, Seulgi; Yoon, Jinhwan

    2015-02-28

    Extensive research efforts have been devoted to the development of hydrogel microfibers for tissue engineering, because the vascular structure is related to the transport of nutrients and oxygen as well as the control of metabolic and mechanical functions in the human body. Even though stimuli-responsive properties would enhance the potential applicability of hydrogel microfibers for artificial tissue architectures, previous studies of their fabrication have not considered changes in the microfibers in response to external stimuli. In this work, we prepared temperature-responsive poly(N-isopropylacrylamide) (PNIPAm) microfibers with controlled shapes and sizes by the in situ photo-polymerization of aqueous monomers loaded in calcium alginate templates generated from microcapillary devices. We found that the shape and size of the hydrogel microfibers could be controlled by adjusting the injection positions of the solutions and varying the diameters of the inner capillary, respectively. We further fabricated light-responsive materials by incorporating photothermal magnetite nanoparticles (MNPs) within the temperature-responsive PNIPAm hydrogel microfibers. Because the MNPs incorporated into the PNIPAm microfibers generated heat upon the absorption of visible light, we could demonstrate volume changes in the microfibers triggered by both visible light irradiation and temperature.

  17. Threat modulates neural responses to looming visual stimuli.

    Science.gov (United States)

    Vagnoni, Eleonora; Lourenco, Stella F; Longo, Matthew R

    2015-09-01

    Objects on a collision course with an observer produce a specific pattern of optical expansion on the retina known as looming, which in theory exactly specifies the time-to-collision (TTC) of approaching objects. It was recently demonstrated that the affective content of looming stimuli influences perceived TTC, with threatening objects judged as approaching sooner than non-threatening objects. Here, the neural mechanisms by which perceived threat modulates spatiotemporal perception were investigated. Participants judged the TTC of threatening (snakes, spiders) or non-threatening (butterflies, rabbits) stimuli, which expanded in size at a rate indicating one of five TTCs. Visual-evoked potentials (VEPs) and oscillatory neural responses measured with electroencephalography were analysed. The arrival time of threatening stimuli was underestimated compared with non-threatening stimuli, though an interaction suggested that this underestimation was not constant across TTCs. Further, both speed of approach and threat modulated both VEPs and oscillatory responses. Speed of approach modulated the N1 parietal and oscillations in the beta band. Threat modulated several VEP components (P1, N1 frontal, N1 occipital, early posterior negativity and late positive potential) and oscillations in the alpha and high gamma band. The results for the high gamma band suggest an interaction between these two factors. Previous evidence suggests that looming stimuli activate sensorimotor areas, even in the absence of an intended action. The current results show that threat disrupts the synchronization over the sensorimotor areas that are likely activated by the presentation of a looming stimulus. © 2015 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

  18. Sex differences in emotional and psychophysiological responses to musical stimuli.

    Science.gov (United States)

    Nater, Urs M; Abbruzzese, Elvira; Krebs, Monika; Ehlert, Ulrike

    2006-11-01

    Although it is known that men and women differ in their music preferences and emotional reactions to music, little is known about sex differences in physiological reactions to music. In our study, we therefore set out to examine the differential reactivity to two musical stimuli that elicit distinct psychological and physiological reaction patterns. Fifty-three healthy subjects (mean age: 26.13, SD: 3.97; 26 males, 27 females) were examined. Heart rate, electrodermal activity, skin temperature, salivary cortisol, salivary alpha-amylase, and psychological variables were assessed during the course of the whole study. Following baseline assessment, two musical stimuli, which were carefully selected and rated in a pre-study as relaxing and pleasant (renaissance music) and arousing and unpleasant (heavy metal), respectively, were introduced. They were presented on two different days in a randomized order. Whereas psychological variables did not differ between men and women, results of electrophysiological measures indicate significantly different reactivity patterns between men and women. Women displayed elevated response curves to the arousing and unpleasant stimulus, whereas men did not. However, no differences were found with regards to endocrine measures in saliva. Our results demonstrate sex differences in reactivity patterns to musical stimuli in psychophysiological measures. In our study, we were able to show that women tend to show hypersensitivity to aversive musical stimuli. This finding is in accordance with previous literature on sex differences in emotion research. Furthermore, our study indicates that the confounding effects of sex differences have to be considered when using musical stimuli for emotion induction.

  19. Stimuli-sensitive nanoparticles for multiple anti-HIV microbicides

    Science.gov (United States)

    Giri, Namita; Oh, Byeongtaek; Lee, Chi H.

    2016-05-01

    This study is aimed to develop and evaluate an advanced intravaginal formulation for the delivery of multiple anti-HIV microbicides. Novel stimuli-sensitive nanoparticles (NPs) which protected the encapsulated drugs from being degraded in acidic pH conditions were made of Eudragit S-100® (ES100®), a pH-sensitive polymer. ES100® NPs were prepared using the quasi-emulsion solvent diffusion technique and loaded with two microbicides namely Tenofovir (TNF) and Etravirine (ETV). The effects of various fabrication parameters on the formulation properties were evaluated for the optimization of ES100® NPs. The morphology of the ES100® NPs was examined by scanning electron microscopy. The cytotoxicity of NPs containing microbicides individually or in a combination was assessed using cell viability and trans-epithelial electrical resistance (TEER) measurements. The cellular uptake rates of the model microbicides by human vaginal epithelial cells, VK2 E6/E7 cells, were evaluated using confocal microscopy and florescence-assisted cell sorting technique. ES100® NPs had a spherical shape, smooth surface, and uniform texture with a little aggregation. The average particle size for NPs loaded with TNF ranged from 125 to 230 nm, whereas those for ETV-loaded NPs ranged from 160 to 280 nm. ES100® NPs had zeta potential in the range of -5 to -10 mV. In-vitro release studies displayed the potential benefits of ES100® NPs in retaining and protecting the loaded microbicides at vaginal pH (acidic), but immediately releasing them as the pH changes to neutral or 7.4 (physiological pH). Cell viability studies demonstrated that ES100® NPs did not exert any cytotoxicity individually or in a combination of both microbicides. TEER measurements confirmed that ES100® NPs loaded with TNF and ETV did not cause any changes in the barrier integrity of VK2 E6/E7 cell monolayer. The cellular uptake study revealed that ES100® NPs were taken by vaginal epithelial cells through the endocytosis

  20. Variation in mouse basolateral amygdala volume is associated with differences in stress reactivity and fear learning.

    Science.gov (United States)

    Yang, Rebecca J; Mozhui, Khyobeni; Karlsson, Rose-Marie; Cameron, Heather A; Williams, Robert W; Holmes, Andrew

    2008-10-01

    A wealth of research identifies the amygdala as a key brain region mediating negative affect, and implicates amygdala dysfunction in the pathophysiology of anxiety disorders. Although there is a strong genetic component to anxiety disorders such as posttraumatic stress disorder (PTSD) there remains debate about whether abnormalities in amygdala function predispose to these disorders. In the present study, groups of C57BL/6 x DBA/2 (B x D) recombinant inbred strains of mice were selected for differences in volume of the basolateral amygdala complex (BLA). Strains with relatively small, medium, or large BLA volumes were compared for Pavlovian fear learning and memory, anxiety-related behaviors, depression-related behavior, and glucocorticoid responses to stress. Strains with relatively small BLA exhibited stronger conditioned fear responses to both auditory tone and contextual stimuli, as compared to groups with larger BLA. The small BLA group also showed significantly greater corticosterone responses to stress than the larger BLA groups. BLA volume did not predict clear differences in measures of anxiety-like behavior or depression-related behavior, other than greater locomotor inhibition to novelty in strains with smaller BLA. Neither striatal, hippocampal nor cerebellar volumes correlated significantly with any behavioral measure. The present data demonstrate a phenotype of enhanced fear conditioning and exaggerated glucocorticoid responses to stress associated with small BLA volume. This profile is reminiscent of the increased fear processing and stress reactivity that is associated with amygdala excitability and reduced amygdala volume in humans carrying loss of function polymorphisms in the serotonin transporter and monoamine oxidase A genes. Our study provides a unique example of how natural variation in amygdala volume associates with specific fear- and stress-related phenotypes in rodents, and further supports the role of amygdala dysfunction in anxiety

  1. Oddity learning in developmentally delayed children: facilitation by means of familiar stimuli.

    Science.gov (United States)

    Bryant, J T; Deckner, C W; Soraci, S A; Baumeister, A A; Blanton, R L

    1988-09-01

    Four of 8 low-functioning, developmentally delayed children initially failed to demonstrate oddity responding under conditions in which ostensibly similar children did show oddity responding (e.g., Soraci et al., 1987). In the context of a multiple baseline across-subjects design, each of the 4 previously unsuccessful children demonstrated statistically significant increases in the percentage of correct oddity responses immediately upon introduction of familiar stimuli. These results indicate that perceptual differentiation enhances relational learning of the type required by the oddity task.

  2. Do Conditional Reinforcers Count?

    OpenAIRE

    Davison, Michael; Baum, William M.

    2006-01-01

    Six pigeons were trained on a procedure in which seven components arranged different food-delivery ratios on concurrent variable-interval schedules each session. The components were unsignaled, lasted for 10 food deliveries, and occurred in random order with a 60-s blackout between components. The schedules were arranged using a switching-key procedure in which two responses on a center key changed the schedules and associated stimuli on two side keys. In Experiment 1, over five conditions, a...

  3. Serotonin and conditioning: focus on Pavlovian psychostimulant drug conditioning.

    Science.gov (United States)

    Carey, Robert J; Damianopoulos, Ernest N

    2015-04-01

    Serotonin containing neurons are located in nuclei deep in the brainstem and send axons throughout the central nervous system from the spinal cord to the cerebral cortex. The vast scope of these connections and interactions enable serotonin and serotonin analogs to have profound effects upon sensory/motor processes. In that conditioning represents a neuroplastic process that leads to new sensory/motor connections, it is apparent that the serotonin system has the potential for a critical role in conditioning. In this article we review the basics of conditioning as well as the serotonergic system and point up the number of non-associative ways in which manipulations of serotonin neurotransmission have an impact upon conditioning. We focus upon psychostimulant drug conditioning and review the contribution of drug stimuli in the use of serotonin drugs to investigate drug conditioning and the important impact drug stimuli can have on conditioning by introducing new sensory stimuli that can create or mask a CS. We also review the ways in which experimental manipulations of serotonin can disrupt conditioned behavioral effects but not the associative processes in conditioning. In addition, we propose the use of the recently developed memory re-consolidation model of conditioning as an approach to assess the possible role of serotonin in associative processes without the complexities of performance effects related to serotonin treatment induced alterations in sensory/motor systems.

  4. The Bank of Standardized Stimuli (BOSS, a new set of 480 normative photos of objects to be used as visual stimuli in cognitive research.

    Directory of Open Access Journals (Sweden)

    Mathieu B Brodeur

    Full Text Available There are currently stimuli with published norms available to study several psychological aspects of language and visual cognitions. Norms represent valuable information that can be used as experimental variables or systematically controlled to limit their potential influence on another experimental manipulation. The present work proposes 480 photo stimuli that have been normalized for name, category, familiarity, visual complexity, object agreement, viewpoint agreement, and manipulability. Stimuli are also available in grayscale, blurred, scrambled, and line-drawn version. This set of objects, the Bank Of Standardized Stimuli (BOSS, was created specifically to meet the needs of scientists in cognition, vision and psycholinguistics who work with photo stimuli.

  5. Neonate Auditory Brainstem Responses to CE-Chirp and CE-Chirp Octave Band Stimuli I: Versus Click and Tone Burst Stimuli.

    Science.gov (United States)

    Cobb, Kensi M; Stuart, Andrew

    The purpose of the study was to generate normative auditory brainstem response (ABR) wave component peak latency and amplitude values for neonates with air- and bone-conducted CE-Chirps and air-conducted CE-Chirp octave band stimuli (i.e., 500, 1000, 2000, and 4000 Hz). A second objective was to compare neonate ABRs to CE-Chirp stimuli with ABR responses to traditional click and tone burst stimuli with the same stimulus parameters. Participants were 168 healthy neonates. ABRs were obtained to air- and bone-conducted CE-Chirp and click stimuli and air-conducted CE-Chirp octave band and tone burst stimuli. The effects of stimulus level, rate, and polarity were examined with air-conducted CE-Chirps and clicks. The effect of stimulus level was also examined with bone-conducted CE-Chirps and clicks and air-conducted CE-Chirp octave band stimuli. In general, ABR wave V amplitudes to air- and bone-conducted CE-Chirp stimuli were significantly larger (p CE-Chirp and CE-Chirp octave band stimuli relative to traditional click and tone burst stimuli. ABRs to air- and bone-conducted CE-Chirps and CE-Chirp octave band stimuli may be valuable in the assessment of newborn infants. However, the prognostic value of such stimuli needs to be validated.

  6. Mathematical modeling of sustainable synaptogenesis by repetitive stimuli suggests signaling mechanisms in vivo.

    Directory of Open Access Journals (Sweden)

    Hiromu Takizawa

    Full Text Available The mechanisms of long-term synaptic maintenance are a key component to understanding the mechanism of long-term memory. From biological experiments, a hypothesis arose that repetitive stimuli with appropriate intervals are essential to maintain new synapses for periods of longer than a few days. We successfully reproduce the time-course of relative numbers of synapses with our mathematical model in the same conditions as biological experiments, which used Adenosine-3', 5'-cyclic monophosphorothioate, Sp-isomer (Sp-cAMPS as external stimuli. We also reproduce synaptic maintenance responsiveness to intervals of Sp-cAMPS treatment accompanied by PKA activation. The model suggests a possible mechanism of sustainable synaptogenesis which consists of two steps. First, the signal transduction from an external stimulus triggers the synthesis of a new signaling protein. Second, the new signaling protein is required for the next signal transduction with the same stimuli. As a result, the network component is modified from the first network, and a different signal is transferred which triggers the synthesis of another new signaling molecule. We refer to this hypothetical mechanism as network succession. We build our model on the basis of two hypotheses: (1 a multi-step network succession induces downregulation of SSH and COFILIN gene expression, which triggers the production of stable F-actin; (2 the formation of a complex of stable F-actin with Drebrin at PSD is the critical mechanism to achieve long-term synaptic maintenance. Our simulation shows that a three-step network succession is sufficient to reproduce sustainable synapses for a period longer than 14 days. When we change the network structure to a single step network, the model fails to follow the exact condition of repetitive signals to reproduce a sufficient number of synapses. Another advantage of the three-step network succession is that this system indicates a greater tolerance of parameter

  7. Effects of low-temperature catalytic pretreatments on coal structure and reactivity in liquefaction. Final technical report, Volume 1 - effects of solvents, catalysts and temperature conditions on conversion and structural changes of low-rank coals

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Lili [Pennsylvania State Univ., University Park, PA (United States); Schobert, Harold H. [Pennsylvania State Univ., University Park, PA (United States); Song, Chunshan [Pennsylvania State Univ., University Park, PA (United States)

    1998-01-01

    The main objectives of this project were to study the effects of low-temperature pretreatments on coal structure and their impacts on subsequent liquefaction. The effects of pretreatment temperatures, catalyst type, coal rank, and influence of solvent were examined. Specific objectives were to identify the basic changes in coal structure induced by catalytic and thermal pretreatments, and to determine the reactivity of the catalytically and thermally treated coals for liquefaction. In the original project management plan it was indicated that six coals would be used for the study. These were to include two each of bituminous, subbituminous, and lignite rank. For convenience in executing the experimental work, two parallel efforts were conducted. The first involved the two lignites and one subbituminous coal; and the second, the two bituminous coals and the remaining subbituminous coal. This Volume presents the results of the first portion of the work, studies on two lignites and one subbituminous coal. The remaining work accomplished under this project will be described and discussed in Volume 2 of this report. The objective of this portion of the project was to determine and compare the effects of solvents, catalysts and reaction conditions on coal liquefaction. Specifically, the improvements of reaction conversion, product distribution, as well as the structural changes in the coals and coal-derived products were examined. This study targeted at promoting hydrogenation of the coal-derived radicals, generated during thermal cleavage of chemical bonds, by using a good hydrogen donor-solvent and an effective catalyst. Attempts were also made in efforts to match the formation and hydrogenation of the free radicals and thus to prevent retrogressive reaction.

  8. Behavioral responses to noxious stimuli shape the perception of pain.

    Science.gov (United States)

    May, Elisabeth S; Tiemann, Laura; Schmidt, Paul; Nickel, Moritz M; Wiedemann, Nina; Dresel, Christian; Sorg, Christian; Ploner, Markus

    2017-03-09

    Pain serves vital protective functions. To fulfill these functions, a noxious stimulus might induce a percept which, in turn, induces a behavioral response. Here, we investigated an alternative view in which behavioral responses do not exclusively depend on but themselves shape perception. We tested this hypothesis in an experiment in which healthy human subjects performed a reaction time task and provided perceptual ratings of noxious and tactile stimuli. A multi-level moderated mediation analysis revealed that behavioral responses are significantly involved in the translation of a stimulus into perception. This involvement was significantly stronger for noxious than for tactile stimuli. These findings show that the influence of behavioral responses on perception is particularly strong for pain which likely reflects the utmost relevance of behavioral responses to protect the body. These observations parallel recent concepts of emotions and entail implications for the understanding and treatment of pain.

  9. Joint attention for stimuli on the hands: Ownership matters

    Directory of Open Access Journals (Sweden)

    Eric eTaylor

    2015-05-01

    Full Text Available The visual system treats the space near the hands with unique, action-related priorities. For example, attention orients slowly to stimuli on the hands (Taylor & Witt, 2014. In this article, we asked whether jointly attended hands are attended in the same way. Specifically, we examined whether ownership over the hand mattered: Do we attend to our hands and the hands of others in the same way? Pairs of participants performed a spatial cueing task with stimuli that could be projected onto one partner’s hands or on a control surface. Results show delayed orienting of attention to targets appearing on the hands, but only for the owner of the hands. For an observer, others’ hands are like any other surface. This result emphasizes the importance of ownership for hand-based effects on vision, and in doing so, is inconsistent with some expectations of the joint action literature.

  10. Joint attention for stimuli on the hands: ownership matters

    Science.gov (United States)

    Taylor, J. E. T.; Pratt, Jay; Witt, Jessica K.

    2015-01-01

    The visual system treats the space near the hands with unique, action-related priorities. For example, attention orients slowly to stimuli on the hands (Taylor and Witt, 2014). In this article, we asked whether jointly attended hands are attended in the same way. Specifically, we examined whether ownership over the hand mattered: do we attend to our hands and the hands of others in the same way? Pairs of participants performed a spatial cueing task with stimuli that could be projected onto one partner’s hands or on a control surface. Results show delayed orienting of attention to targets appearing on the hands, but only for the owner of the hands. For an observer, others’ hands are like any other surface. This result emphasizes the importance of ownership for hand-based effects on vision, and in doing so, is inconsistent with some expectations of the joint action literature. PMID:25983713

  11. Functional stimuli responsive hydrogel devices by self-folding

    Science.gov (United States)

    Yoon, ChangKyu; Xiao, Rui; Park, JaeHyun; Cha, Jaepyeong; Nguyen, Thao D.; Gracias, David H.

    2014-09-01

    We describe a photolithographic approach to create functional stimuli responsive, self-folding, microscale hydrogel devices using thin, gradient cross-linked hinges and thick, fully cross-linked panels. The hydrogels are composed of poly (N-isopropylacrylamide-co-acrylic acid) (pNIPAM-AAc) with reversible stimuli responsive properties just below physiological temperatures. We show that a variety of three-dimensional structures can be formed and reversibly actuated by temperature or pH. We experimentally characterized the swelling and mechanical properties of pNIPAM-AAc and developed a finite element model to rationalize self-folding and its variation with hinge thickness and swelling ratio. Finally, we highlight applications of this approach in the creation of functional devices such as self-folding polymeric micro-capsules, untethered micro-grippers and thermally steered micro-mirror systems.

  12. Stimuli-responsive hydrogels in drug delivery and tissue engineering.

    Science.gov (United States)

    Sood, Nikhil; Bhardwaj, Ankur; Mehta, Shuchi; Mehta, Abhinav

    2016-01-01

    Hydrogels are the three-dimensional network structures obtained from a class of synthetic or natural polymers which can absorb and retain a significant amount of water. Hydrogels are one of the most studied classes of polymer-based controlled drug release. These have attracted considerable attention in biochemical and biomedical fields because of their characteristics, such as swelling in aqueous medium, biocompatibility, pH and temperature sensitivity or sensitivity towards other stimuli, which can be utilized for their controlled zero-order release. The hydrogels are expected to explore new generation of self-regulated delivery system having a wide array of desirable properties. This review highlights the exciting opportunities and challenges in the area of hydrogels. Here, we review different literatures on stimuli-sensitive hydrogels, such as role of temperature, electric potential, pH and ionic strength to control the release of drug from hydrogels.

  13. Orexin receptor antagonist-induced sleep does not impair the ability to wake in response to emotionally salient acoustic stimuli in dogs

    Directory of Open Access Journals (Sweden)

    Pamela L. Tannenbaum

    2014-05-01

    Full Text Available The ability to awaken from sleep in response to important stimuli is a critical feature of normal sleep, as is maintaining sleep continuity in the presence of irrelevant background noise. Dual orexin receptor antagonists (DORAs effectively promote sleep across species by targeting the evolutionarily conserved wake-promoting orexin signaling pathway. This study in dogs investigated whether DORA-induced sleep preserved the ability to awaken appropriately to salient acoustic stimuli but remain asleep when exposed to irrelevant stimuli. Sleep and wake in response to DORAs, vehicle, GABA-A receptor modulators (diazepam, eszopiclone and zolpidem and antihistamine (diphenhydramine administration were evaluated in telemetry-implanted adult dogs with continuous electrocorticogram, electromyogram, electrooculogram, and activity recordings. DORAs induced sleep, but GABA-A modulators and antihistamine induced paradoxical hyperarousal. Thus, salience gating studies were conducted during DORA-22 (0.3, 1, and 5 mg/kg; day and night and vehicle nighttime sleep. The acoustic stimuli were either classically conditioned using food reward and positive attention (salient stimulus or presented randomly (neutral stimulus. Once conditioned, the tones were presented at sleep times corresponding to maximal DORA-22 exposure. In response to the salient stimuli, dogs woke completely from vehicle and orexin-antagonized sleep across all sleep stages but rarely awoke to neutral stimuli. Notably, acute pharmacological antagonism of orexin receptors paired with emotionally salient anticipation produced wake, not cataplexy, in a species where genetic (chronic loss of orexin receptor signaling leads to narcolepsy/cataplexy. DORA-induced sleep in this species thereby retains the desired capacity to awaken to emotionally salient acoustic stimuli while preserving uninterrupted sleep in response to irrelevant stimuli.

  14. Perceptual memory drives learning of retinotopic biases for bistable stimuli.

    Directory of Open Access Journals (Sweden)

    Aidan Peter Murphy

    2014-02-01

    Full Text Available The visual system exploits past experience at multiple timescales to resolve perceptual ambiguity in the retinal image. For example, perception of a bistable stimulus can be biased towards one interpretation over another when preceded by a brief presentation of a disambiguated version of the stimulus (positive priming or through intermittent presentations of the ambiguous stimulus (stabilization. Similarly, prior presentations of unambiguous stimuli can be used to explicitly train a long-lasting association between a percept and a retinal location (perceptual association. These phenonema have typically been regarded as independent processes, with short-term biases attributed to perceptual memory and longer-term biases described as associative learning. Here we tested for interactions between these two forms of experience-dependent perceptual bias and demonstrate that short-term processes strongly influence long-term outcomes. We first demonstrate that the establishment of long-term perceptual contingencies does not require explicit training by unambiguous stimuli, but can arise spontaneously during the periodic presentation of brief, ambiguous stimuli. Using rotating Necker cube stimuli, we observed enduring, retinotopically specific perceptual biases that were expressed from the outset and remained stable for up to forty minutes, consistent with the known phenomenon of perceptual stabilization. Further, bias was undiminished after a break period of five minutes, but was readily reset by interposed periods of continuous, as opposed to periodic, ambiguous presentation. Taken together, the results demonstrate that perceptual biases can arise naturally and may principally reflect the brain’s tendency to favor recent perceptual interpretation at a given retinal location. Further, they suggest that an association between retinal location and perceptual state, rather than a physical stimulus, is sufficient to generate long-term biases in perceptual

  15. A Microfluidic Device for Spatiotemporal Delivery of Stimuli to Cells

    Directory of Open Access Journals (Sweden)

    Zubaidah Ningsih

    2015-03-01

    Full Text Available Living cells encounter many stimuli from the immediate environment. Receptors recognize these environmental cues and transduce signals to produce cell responses. The frequency of a signal is now emerging as an important factor determining cell responses. As a componentry system in understanding temporal stimulation, microfluidic devices allow the observation of cell behaviour under dynamic stimulation and controllable environment. In this paper we describe the design, construction and characterization of a microfluidic device suitable for cell stimulation studies.

  16. Stimuli responsive smart-gels realized via modular protein design

    OpenAIRE

    2010-01-01

    Smart-gels have a variety of applications including tissue engineering and controlled drug delivery. Here we present a modular, bottom-up approach that permits the creation of protein-based smart-gels with encoded morphology, functionality, and responsiveness to external stimuli. The properties of these gels are encoded by the proteins from which they are synthesized. In particular, the strength and density of the network of intermolecular cross-links are specified by the interactions of the ...

  17. Attention bias for paranoia-relevant visual stimuli in schizophrenia.

    Science.gov (United States)

    Moritz, Steffen; Laudan, Anna

    2007-09-01

    A number of studies indicate that patients with schizophrenia share a bias for paranoia-relevant material. The presence of an attentional bias for such stimuli would be of utter importance for our pathogenetic understanding of the disorder in view of ample evidence that patients with schizophrenia gather little information before arriving at strong conclusions: A both scarce and affectively biased data selection of available information may heavily distort its inner representation and thus prompt the formation of false beliefs. To date, the profile of this putative attentional bias in schizophrenia (e.g., automatic vs. controlled; hypervigilance towards vs. problems to disengage from such stimuli) is not fully uncovered. To shed light on this aspect of information processing in schizophrenia, we administered a novel task based on the inhibition of return paradigm (IOR). Twenty-four schizophrenia patients and thirty-four healthy controls were presented neutral (e.g., cup), anxiety-relevant (e.g., shark), and paranoia-relevant cue pictures (e.g., gun) at either of two possible locations. Subsequent to either a short or long interval, a target appeared at the same or opposite location. Participants were requested to press a spatially corresponding button. Both currently paranoid and nonparanoid schizophrenia patients responded faster to all kinds of targets following paranoia-relevant pictures, that is, such stimuli speeded reaction times irrespective of the cue-target interval and spatial correspondence. This indicates that paranoia-relevant information generally alerts patients more than other stimuli and facilitates processing of subsequent information. Possible implications of this finding for our understanding of delusion formation and maintenance are outlined.

  18. Neural activation toward erotic stimuli in homosexual and heterosexual males.

    Science.gov (United States)

    Kagerer, Sabine; Klucken, Tim; Wehrum, Sina; Zimmermann, Mark; Schienle, Anne; Walter, Bertram; Vaitl, Dieter; Stark, Rudolf

    2011-11-01

    Studies investigating sexual arousal exist, yet there are diverging findings on the underlying neural mechanisms with regard to sexual orientation. Moreover, sexual arousal effects have often been confounded with general arousal effects. Hence, it is still unclear which structures underlie the sexual arousal response in homosexual and heterosexual men. Neural activity and subjective responses were investigated in order to disentangle sexual from general arousal. Considering sexual orientation, differential and conjoint neural activations were of interest. The functional magnetic resonance imaging (fMRI) study focused on the neural networks involved in the processing of sexual stimuli in 21 male participants (11 homosexual, 10 heterosexual). Both groups viewed pictures with erotic content as well as aversive and neutral stimuli. The erotic pictures were subdivided into three categories (most sexually arousing, least sexually arousing, and rest) based on the individual subjective ratings of each participant. Blood oxygen level-dependent responses measured by fMRI and subjective ratings. A conjunction analysis revealed conjoint neural activation related to sexual arousal in thalamus, hypothalamus, occipital cortex, and nucleus accumbens. Increased insula, amygdala, and anterior cingulate gyrus activation could be linked to general arousal. Group differences emerged neither when viewing the most sexually arousing pictures compared with highly arousing aversive pictures nor compared with neutral pictures. Results suggest that a widespread neural network is activated by highly sexually arousing visual stimuli. A partly distinct network of structures underlies sexual and general arousal effects. The processing of preferred, highly sexually arousing stimuli recruited similar structures in homosexual and heterosexual males. © 2011 International Society for Sexual Medicine.

  19. Mechanism of unpinning spirals by a series of stimuli.

    Science.gov (United States)

    Gao, Xiang; Zhang, Hong

    2014-06-01

    Antitachycardia pacing (ATP) is widely used to terminate tachycardia before it proceeds to lethal fibrillation. The important prerequisite for successful ATP is unpinning of the spirals anchored to the obstacle by a series of stimuli. Here, to understand the mechanism of unpinning spirals by ATP, we propose a theoretical explanation based on a nonlinear eikonal relation and a kinematical model. The theoretical results are quantitatively consistent with the numerical simulations in both weak and high excitabilities.

  20. Music Influences Ratings of the Affect of Visual Stimuli

    OpenAIRE

    Waldie E Hanser; Mark, Ruth E

    2013-01-01

    This review provides an overview of recent studies that have examined how music influences the judgment of emotional stimuli, including affective pictures and film clips. The relevant findings are incorporated within a broader theory of music and emotion, and suggestions for future research are offered.Music is important in our daily lives, and one of its primary uses by listeners is the active regulation of one's mood. Despite this widespread use as a regulator of mood and its general pervas...

  1. Temporal sensitivity. [time dependent human perception of visual stimuli

    Science.gov (United States)

    Watson, Andrew B.

    1986-01-01

    Human visual temporal sensitivity is examined. The stimuli used to measure temporal sensitivity are described and the linear systems theory is reviewed in terms of temporal sensitivity. A working model which represents temporal sensitivity is proposed. The visibility of a number of temporal wave forms, sinusoids, rectangular pulses, and pulse pairs, is analyzed. The relation between spatial and temporal effects is studied. Temporal variations induced by image motion and the effects of light adaptation on temporal sensitivity are considered.

  2. Neural correlates of quality during perception of audiovisual stimuli

    CERN Document Server

    Arndt, Sebastian

    2016-01-01

    This book presents a new approach to examining perceived quality of audiovisual sequences. It uses electroencephalography to understand how exactly user quality judgments are formed within a test participant, and what might be the physiologically-based implications when being exposed to lower quality media. The book redefines experimental paradigms of using EEG in the area of quality assessment so that they better suit the requirements of standard subjective quality testings. Therefore, experimental protocols and stimuli are adjusted accordingly. .

  3. Attention modulates the dorsal striatum response to love stimuli.

    Science.gov (United States)

    Langeslag, Sandra J E; van der Veen, Frederik M; Röder, Christian H

    2014-02-01

    In previous functional magnetic resonance imaging (fMRI) studies concerning romantic love, several brain regions including the caudate and putamen have consistently been found to be more responsive to beloved-related than control stimuli. In those studies, infatuated individuals were typically instructed to passively view the stimuli or to think of the viewed person. In the current study, we examined how the instruction to attend to, or ignore the beloved modulates the response of these brain areas. Infatuated individuals performed an oddball task in which pictures of their beloved and friend served as targets and distractors. The dorsal striatum showed greater activation for the beloved than friend, but only when they were targets. The dorsal striatum actually tended to show less activation for the beloved than the friend when they were distractors. The longer the love and relationship duration, the smaller the response of the dorsal striatum to beloved-distractor stimuli was. We interpret our findings in terms of reinforcement learning. By virtue of using a cognitive task with a full factorial design, we show that the dorsal striatum is not activated by beloved-related information per se, but only by beloved-related information that is attended.

  4. Non-nutritive sweeteners are not super-normal stimuli

    Science.gov (United States)

    Antenucci, Rachel G.; Hayes, John E.

    2014-01-01

    Background It is often claimed that non-nutritive sweeteners (NNS) are ‘sweeter than sugar’, with the implicit implication high potency sweeteners are super-normal stimuli that encourage exaggerated responses. This study aimed to investigate the perceived sweetness intensity of a variety of nutritive (Sucrose, Maple Syrup, and Agave Nectar) and NNS (Acesulfame-K (AceK), Rebaudioside A (RebA), Aspartame, and Sucralose) in a large cohort of untrained participants using contemporary psychophysical methods. Methods Participants (n=401 total) rated the intensity of sweet, bitter, and metallic sensations for nutritive and NNS in water using the general labeled magnitude scale (gLMS). Results Sigmoidal Dose-Response functions were observed for all stimuli except AceK. That is, sucrose follows a sigmoidal function if the data are not artifactually linearized via prior training. More critically, there is no evidence that NNS have a maximal sweetness (intensity) greater than sucrose; indeed, the maximal sweetness for AceK, RebA and Sucralose were significantly lower than for concentrated sucrose. For these sweeteners, mixture suppression due to endogenous dose-dependent bitter or metallic sensations appears to limit maximal perceived sweetness. Conclusions In terms of perceived sweetness, non-nutritive sweeteners cannot be considered super-normal stimuli. These data do not support the view that non-nutritive sweeteners hijack or over-stimulate sweet receptors to product elevated sweet sensations. PMID:24942868

  5. Spatial localization of electrotactile stimuli on the fingertip in humans.

    Science.gov (United States)

    Bobich, L R; Warren, J P; Sweeney, J D; Tillery, S I Helms; Santello, M

    2007-12-01

    This study was designed to determine the extent to which sensations elicited by discrete electrotactile stimulation can be spatially localized, with a qualitative comparison to mechanical stimulation, in a 2 x 2 electrode array on the fingertip. Electrotactile stimulation was delivered in two modes: (1) same current to all locations (constant) or (2) current adjusted to perceptual threshold of each location (varied). For each stimulus location, subjects were asked to identify the location of the stimulus. Mechanical stimulation of the same locations on the fingerpad was delivered through von Frey hairs (0.07, 0.2 and 0.4 g). The percentage of accurate responses was computed for all stimulation modes. We found that the accuracy of discrimination of stimulus location in both the constant (46%) and varied (40%) electrotactile stimulation modes was significantly higher than chance level (25%; p < 0.01). Furthermore, subjects were significantly more accurate in discriminating electrotactile stimuli in the constant than in the varied mode (p < 0.05). We also found that the accuracy of spatial discrimination was dependent on stimulation site for mechanical, but not electrotactile stimulation. Finally, we found a significant difference in accuracy over the duration of the experiment only for mechanical modes, which may indicate that electrotactile stimuli are less biased over time. These results suggest that, although low in accuracy, human subjects are able to extract spatial information from electrotactile stimuli. Further research is needed to optimize the amount of the information that can be delivered through electrotactile stimulation.

  6. Dynamism of Stimuli-Responsive Nanohybrids: Environmental Implications

    Directory of Open Access Journals (Sweden)

    Jaime Plazas-Tuttle

    2015-06-01

    Full Text Available Nanomaterial science and design have shifted from generating single passive nanoparticles to more complex and adaptive multi-component nanohybrids. These adaptive nanohybrids (ANHs are designed to simultaneously perform multiple functions, while actively responding to the surrounding environment. ANHs are engineered for use as drug delivery carriers, in tissue-engineered templates and scaffolds, adaptive clothing, smart surface coatings, electrical switches and in platforms for diversified functional applications. Such ANHs are composed of carbonaceous, metallic or polymeric materials with stimuli-responsive soft-layer coatings that enable them to perform such switchable functions. Since ANHs are engineered to dynamically transform under different exposure environments, evaluating their environmental behavior will likely require new approaches. Literature on polymer science has established a knowledge core on stimuli-responsive materials. However, translation of such knowledge to environmental health and safety (EHS of these ANHs has not yet been realized. It is critical to investigate and categorize the potential hazards of ANHs, because exposure in an unintended or shifting environment could present uncertainty in EHS. This article presents a perspective on EHS evaluation of ANHs, proposes a principle to facilitate their identification for environmental evaluation, outlines a stimuli-based classification for ANHs and discusses emerging properties and dynamic aspects for systematic EHS evaluation.

  7. Differences in Swallowing between High and Low Concentration Taste Stimuli

    Directory of Open Access Journals (Sweden)

    Ahmed Nagy

    2014-01-01

    Full Text Available Taste is a property that is thought to potentially modulate swallowing behavior. Whether such effects depend on taste, intensity remains unclear. This study explored differences in the amplitudes of tongue-palate pressures in swallowing as a function of taste stimulus concentration. Tongue-palate pressures were collected in 80 healthy women, in two age groups (under 40, over 60, stratified by genetic taste status (nontasters, supertasters. Liquids with different taste qualities (sweet, sour, salty, and bitter were presented in high and low concentrations. General labeled magnitude scale ratings captured perceived taste intensity and liking/disliking of the test liquids. Path analysis explored whether factors of taste, concentration, age group, and/or genetic taste status impacted: (1 perceived intensity; (2 palatability; and (3 swallowing pressures. Higher ratings of perceived intensity were found in supertasters and with higher concentrations, which were more liked/disliked than lower concentrations. Sweet stimuli were more palatable than sour, salty, or bitter stimuli. Higher concentrations elicited stronger tongue-palate pressures independently and in association with intensity ratings. The perceived intensity of a taste stimulus varies as a function of stimulus concentration, taste quality, participant age, and genetic taste status and influences swallowing pressure amplitudes. High-concentration salty and sour stimuli elicit the greatest tongue-palate pressures.

  8. The Visual Mismatch Negativity Elicited with Visual Speech Stimuli

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    Benjamin T. Files

    2013-07-01

    Full Text Available The visual mismatch negativity (vMMN, deriving from the brain’s response to stimulus deviance, is thought to be generated by the cortex that represents the stimulus. The vMMN response to visual speech stimuli was used in a study of the lateralization of visual speech processing. Previous research suggested that the right posterior temporal cortex has specialization for processing simple non-speech face gestures, and the left posterior temporal cortex has specialization for processing visual speech gestures. Here, visual speech consonant-vowel (CV stimuli with controlled perceptual dissimilarities were presented in an electroencephalography (EEG vMMN paradigm. The vMMNs were obtained using the comparison of event-related potentials (ERPs for separate CVs in their roles as deviant versus their roles as standard. Four separate vMMN contrasts were tested, two with the perceptually far deviants (i.e., zha or fa and two with the near deviants (i.e., zha or ta. Only far deviants evoked the vMMN response over the left posterior temporal cortex. All four deviants evoked vMMNs over the right posterior temporal cortex. The results are interpreted as evidence that the left posterior temporal cortex represents speech stimuli that are perceived as different consonants, and the right posterior temporal cortex represents face gestures that may not be discriminable as different CVs.

  9. Renormalized Volume

    Science.gov (United States)

    Gover, A. Rod; Waldron, Andrew

    2017-09-01

    We develop a universal distributional calculus for regulated volumes of metrics that are suitably singular along hypersurfaces. When the hypersurface is a conformal infinity we give simple integrated distribution expressions for the divergences and anomaly of the regulated volume functional valid for any choice of regulator. For closed hypersurfaces or conformally compact geometries, methods from a previously developed boundary calculus for conformally compact manifolds can be applied to give explicit holographic formulæ for the divergences and anomaly expressed as hypersurface integrals over local quantities (the method also extends to non-closed hypersurfaces). The resulting anomaly does not depend on any particular choice of regulator, while the regulator dependence of the divergences is precisely captured by these formulæ. Conformal hypersurface invariants can be studied by demanding that the singular metric obey, smoothly and formally to a suitable order, a Yamabe type problem with boundary data along the conformal infinity. We prove that the volume anomaly for these singular Yamabe solutions is a conformally invariant integral of a local Q-curvature that generalizes the Branson Q-curvature by including data of the embedding. In each dimension this canonically defines a higher dimensional generalization of the Willmore energy/rigid string action. Recently, Graham proved that the first variation of the volume anomaly recovers the density obstructing smooth solutions to this singular Yamabe problem; we give a new proof of this result employing our boundary calculus. Physical applications of our results include studies of quantum corrections to entanglement entropies.

  10. The Influence of Various Distraction Stimuli on Affective Responses during Recumbent Cycle Ergometry

    Directory of Open Access Journals (Sweden)

    Paul C. Miller

    2016-03-01

    Full Text Available (1 Background: Acute bouts of exercise have been associated with affective changes. Exercise supplemented with distraction may divert attention from unpleasant feelings commonly associated with exercise to more pleasant feelings. The purpose of this study was to compare affective responses to exercise with and without distraction. (2 Methods: 25 individuals volunteered for this investigation and completed all three conditions. This study included three 30 min cycle ergometry exercise conditions, a control condition with no stimuli and two test conditions; one supplemented with a self-selected video and the other self-selected music. The Feeling Scale (FS was administered prior to, every 10 min during, immediately following, and 10 min post exercise. (3 Results: These data demonstrate a significant condition effect for FS during exercise. The condition effect was due to FS being greater in the video and distraction conditions. There was no time by condition interaction seen during exercise. (4 Conclusion: These data indicate that distraction may be effective in supporting a more pleasant exercise experience and could potentially increase exercise adherence.

  11. Thermal facial reactivity patterns predict social categorization bias triggered by unconscious and conscious emotional stimuli.

    Science.gov (United States)

    Ponsi, Giorgia; Panasiti, Maria Serena; Rizza, Giulia; Aglioti, Salvatore Maria

    2017-08-30

    Members of highly social species decode, interpret, and react to the emotion of a conspecific depending on whether the other belongs to the same (ingroup) or different (outgroup) social group. While studies indicate that consciously perceived emotional stimuli drive social categorization, information about how implicit emotional stimuli and specific physiological signatures affect social categorization is lacking. We addressed this issue by exploring whether subliminal and supraliminal affective priming can influence the categorization of neutral faces as ingroup versus outgroup. Functional infrared thermal imaging was used to investigate whether the effect of affective priming on the categorization decision was moderated by the activation of the sympathetic nervous system (SNS). During the subliminal condition, we found that stronger SNS activation after positive or negative affective primes induced ingroup and outgroup face categorization, respectively. The exact opposite pattern (i.e. outgroup after positive and ingroup after negative primes) was observed in the supraliminal condition. We also found that misattribution effects were stronger in people with low emotional awareness, suggesting that this trait moderates how one recognizes SNS signals and employs them for unrelated decisions. Our results allow the remarkable implication that low-level affective reactions coupled with sympathetic activation may bias social categorization. © 2017 The Author(s).

  12. Discrimination of two neighboring intra- and intermodal empty time intervals marked by three successive stimuli.

    Science.gov (United States)

    Kuroda, Tsuyoshi; Hasuo, Emi; Labonté, Katherine; Laflamme, Vincent; Grondin, Simon

    2014-06-01

    We investigated the discrimination of two neighboring intra- or inter-modal empty time intervals marked by three successive stimuli. Each of the three markers was a flash (visual-V) or a sound (auditory-A). The first and last markers were of the same modality, while the second one was either A or V, resulting in four conditions: VVV, VAV, AVA and AAA. Participants judged whether the second interval, whose duration was systematically varied, was shorter or longer than the 500-ms first interval. Compared with VVV and AAA, discrimination was impaired with VAV, but not so much with AVA (in Experiment 1). Whereas VAV and AVA consisted of the same set of single intermodal intervals (VA and AV), discrimination was impaired in the VAV compared to the AVA condition. This difference between VAV and AVA could not be attributed to the participants' strategy to perform the discrimination task, e.g., ignoring the standard interval or replacing the visual stimuli with sounds in their mind (in Experiment 2). These results are discussed in terms of sequential grouping according to sensory similarity.

  13. Single Cell Response to Time-dependent Stimuli using a Microfluidic Bioreactor

    Science.gov (United States)

    Johnson-Chavarria, Eric M.; Agrawal, Utsav; Tanyeri, Melikhan; Kuhlman, Thomas E.; Schroeder, Charles M.

    2014-03-01

    Cellular adaptation is critical for survival under uncertain or dynamic environmental conditions. Recent studies have reported the ability of biological systems to implement low-pass filters to distinguish high frequency noise in environmental stimuli from lower frequency input signals, yet we still lack a complete understanding of this phenomenon. In this work, we report a microfluidic-based platform for single cell analysis that provides dynamic control over periodic, time-dependent culture media. Single cells are confined in free solution by the sole action of gentle fluid flow, thereby enabling non-perturbative trapping of cells for long time scales. In this way, our microfluidic-based technique provides the ability to control external stimuli with precise methods while observing non-adherent cells over long timescales. Using this approach, we observed intranucleoid diffusion of genetic repressor proteins released from a chromosomal binding array. Overall, this microfluidic approach provides a direct method for sustaining periodic environmental conditions, measuring growth rates, and detecting gene expression of single cells in free solution. Funded by NIH Pathway to Independence (PI) Award, 4R00HG004183-03. This work was supported by the National Science Foundation through a Graduate Research Fellowship to Eric M. Johnson-Chavarria.

  14. Deficient distracter inhibition and enhanced facilitation for emotional stimuli in depression: an ERP study.

    Science.gov (United States)

    Dai, Qin; Feng, Zhengzhi; Koster, Ernst H W

    2011-02-01

    The aim of the present study was to investigate distracter inhibition ability for emotional faces in depression using a negative affective priming (NAP) task combined with event-related potentials (ERP). The reaction times and the ERP amplitudes were recorded during the task. In a first behavioral experiment, control participants (NC), participants who were currently remitted (RMD), and participants diagnosed with a current major depressive disorder (MDD), performed a modified NAP task. The main finding was that compared with the NC group, MDD participants had enhanced positive priming and less inhibition of sad faces. RMD individuals were characterized by general inhibitory impairments for all emotional faces and a facilitation for sad faces compared with NC individuals. In a second experiment combing the modified NAP task with ERP, the MDD participants had a larger P1 and P3 amplitude for sad faces in the positive priming condition compared with the other groups, and smaller P3 amplitude for sad faces in negative priming condition compared with other faces. Interestingly, RMD participants showed a distinct pattern of results compared with NC and MDD participants. Across the experiments, it can be concluded that MDD participants have deficient distracter inhibition and excessive facilitation for negative stimuli. The RMD participants show a mixed pattern of deficient distracter inhibition and excessive facilitation for both positive and negative stimuli. The results are in line with the idea that impaired distracter inhibition of emotional material is a cognitive risk factor of depression.

  15. Evoked potentials elicited by natural stimuli in the brain of unanesthetized crayfish.

    Science.gov (United States)

    Hernández-Falcón, J; Serrato, J; Ramón, F

    1999-05-01

    Experiments were conducted to test some characteristics of vision by crayfish underwater and in air, and determine possible motion reactions elicited in response to naturalistic or quasi-ethological visual stimuli. Chronically implanted electrodes on the brain were used to record visually evoked potentials in response to moving bars at different speeds or to fish of different sizes. Electroretinograms were also recorded to detect when an object or a shadow appeared in the crayfish visual field. Ongoing brain activity is mild under basal conditions, but increases in RMS by approximately 6% in response to bar passage and 12 to 53% in response to fish motionless or swimming in front of the crayfish. When crayfish are free to move, fish swimming in front of them elicit intense brain activity, together with displacement toward them and an attempt to grab them. Visual evoked potentials are elicited by moving objects as small as 1 degree at a distance of 30 cm in air as well as underwater. None of the stimuli used induced evident behavioral responses under our conditions. We conclude that vision-action activities can be divided into (a) vision of irrelevant objects with short lasting electrical activity and no motion in response to it; (b) vision of mildly interesting objects with long-lasting electrical effects, but no motion in response to it; and (c) vision of relevant objects with appropriate motion reaction.

  16. Development of degradable renewable polymers and stimuli-responsive nanocomposites

    Science.gov (United States)

    Eyiler, Ersan

    The overall goal of this research was to explore new living radical polymerization methods and the blending of renewable polymers. Towards this latter goal, polylactic acid (PLA) was blended with a new renewable polymer, poly(trimethylene-malonate) (PTM), with the aim of improving mechanical properties, imparting faster degradation, and examining the relationship between degradation and mechanical properties. Blend films of PLA and PTM with various ratios (5, 10, and 20 wt %) were cast from chloroform. Partially miscible blends exhibited Young's modulus and elongation-to-break values that significantly extend PLA's usefulness. Atomic force microscopy (AFM) data showed that incorporation of 10 wt% PTM into PLA matrix exhibited a Young's modulus of 4.61 GPa, which is significantly higher than that of neat PLA (1.69 GPa). The second part of the bioplastics study involved a one-week hydrolytic degradation study of PTM and another new bioplastic, poly(trimethylene itaconate) (PTI) using DI water (pH 5.4) at room temperature, and the effects of degradation on crystallinity and mechanical properties of these films were examined by differential scanning calorimetry (DSC) and AFM. PTI showed an increase in crystallinity with degradation, which was attributed to predominately degradation of free amorphous regions. Depending on the crystallinity, the elastic modulus increased at first, and decreased slightly. Both bulk and surface-tethered stimuli-responsive polymers were studied on amine functionalized magnetite (Fe3O4) nanoparticles. Stimuli-responsive polymers studied, including poly(N-isopropylacrylamide) (PNIPAM), poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA), and poly(itaconic acid) (PIA), were grafted via surface-initiated aqueous atom transfer radical polymerization (SI-ATRP). Both Fourier transform infrared spectroscopy (FTIR) and x-ray photoelectron spectroscopy (XPS) spectroscopies showed the progression of the grafting. The change in particle size as a

  17. Taste coding of complex naturalistic taste stimuli and traditional taste stimuli in the parabrachial pons of the awake, freely licking rat.

    Science.gov (United States)

    Sammons, Joshua D; Weiss, Michael S; Victor, Jonathan D; Di Lorenzo, Patricia M

    2016-07-01

    Several studies have shown that taste-responsive cells in the brainstem taste nuclei of rodents respond to sensory qualities other than gustation. Such data suggest that cells in the classical gustatory brainstem may be better tuned to respond to stimuli that engage multiple sensory modalities than to stimuli that are purely gustatory. Here, we test this idea by recording the electrophysiological responses to complex, naturalistic stimuli in single neurons in the parabrachial pons (PbN, the second neural relay in the central gustatory pathway) in awake, freely licking rats. Following electrode implantation and recovery, we presented both prototypical and naturalistic taste stimuli and recorded the responses in the PbN. Prototypical taste stimuli (NaCl, sucrose, citric acid, and caffeine) and naturalistic stimuli (clam juice, grape juice, lemon juice, and coffee) were matched for taste quality and intensity (concentration). Umami (monosodium glutamate + inosine monophosphate) and fat (diluted heavy cream) were also tested. PbN neurons responded to naturalistic stimuli as much or more than to prototypical taste stimuli. Furthermore, they convey more information about naturalistic stimuli than about prototypical ones. Moreover, multidimensional scaling analyses showed that across unit responses to naturalistic stimuli were more widely separated than responses to prototypical taste stimuli. Interestingly, cream evoked a robust and widespread response in PbN cells. Collectively, these data suggest that natural foods are more potent stimulators of PbN cells than purely gustatory stimuli. Probing PbN cells with pure taste stimuli may underestimate the response repertoire of these cells.

  18. The effect of Ramadan fasting on spatial attention through emotional stimuli

    Directory of Open Access Journals (Sweden)

    Molavi M

    2016-05-01

    Full Text Available Maziyar Molavi, Jasmy Yunus, Nugraha P Utama Department of Clinical Sciences, Faculty of Biosciences and Medical Engineering (FBME, Universiti Teknologi Malaysia (UTM, Johor Bahru, Johor, MalaysiaAbstract: Fasting can influence psychological and mental states. In the current study, the effect of periodical fasting on the process of emotion through gazed facial expression as a realistic multisource of social information was investigated for the first time. The dynamic cue-target task was applied via behavior and event-related potential measurements for 40 participants to reveal the temporal and spatial brain activities – before, during, and after fasting periods. The significance of fasting included several effects. The amplitude of the N1 component decreased over the centroparietal scalp during fasting. Furthermore, the reaction time during the fasting period decreased. The self-measurement of deficit arousal as well as the mood increased during the fasting period. There was a significant contralateral alteration of P1 over occipital area for the happy facial expression stimuli. The significant effect of gazed expression and its interaction with the emotional stimuli was indicated by the amplitude of N1. Furthermore, the findings of the study approved the validity effect as a congruency between gaze and target position, as indicated by the increment of P3 amplitude over centroparietal area as well as slower reaction time from behavioral response data during incongruency or invalid condition between gaze and target position compared with those during valid condition. Results of this study proved that attention to facial expression stimuli as a kind of communicative social signal was affected by fasting. Also, fasting improved the mood of practitioners. Moreover, findings from the behavioral and event-related potential data analyses indicated that the neural dynamics of facial emotion are processed faster than that of gazing, as the participants

  19. Conditioned Reinforcement and Response Strength

    Science.gov (United States)

    Shahan, Timothy A.

    2010-01-01

    Stimuli associated with primary reinforcers appear themselves to acquire the capacity to strengthen behavior. This paper reviews research on the strengthening effects of conditioned reinforcers within the context of contemporary quantitative choice theories and behavioral momentum theory. Based partially on the finding that variations in…

  20. P1-32: Response of Human Visual System to Paranormal Stimuli Appearing in Three-Dimensional Display

    Directory of Open Access Journals (Sweden)

    Jisoo Hong

    2012-10-01

    Full Text Available Three-dimensional (3D display became one of indispensable features of commercial TVs in recent years. However, the 3D content displayed by 3D display may contain the abrupt change of depth when the scene changes, which might be considered as a paranormal stimulus. Because the human visual system is not accustomed to such paranormal stimuli in natural conditions, they can cause unexpected responses which usually induce discomfort. Following the change of depth expressed by 3D display, the eyeballs rotate to match the convergence to the new 3D image position. The amount of rotation varies according to the initial longitudinal location and depth displacement of 3D image. Because the change of depth is abrupt, there is delay in human visual system following the change and such delay can be a source of discomfort. To guarantee the safety in watching 3D TV, the acceptable level of displacement in the longitudinal direction should be revealed quantitatively. Additionally, the artificially generated scenes also can provide paranormal stimuli such as periodic depth variations. In the presentation, we investigate the response of human visual system to such paranormal stimuli given by 3D display system. Using the result of investigation, we can give guideline to creating the 3D content to minimize the discomfort coming from the paranormal stimuli.

  1. Temporal response properties to second-order visual stimuli in the LGN of cats

    Institute of Scientific and Technical Information of China (English)

    XU PengJing; YE Xiang; ZHOU Yifeng

    2007-01-01

    Visual stimuli occurring naturally are rich in instances of objects delineated from the backgrounds only by differences in luminance, which is called first-order stimuli, as well as those defined by differences of contrast or texture, referred to as second-order stimuli.The neuronal mechanism for processing second-order stimuli is still unclear.In this study, we compared the responses of cat LGN (lateral geniculate nucleus) cells to second-order stimuli at five temporal frequencies to their responses to first-order stimuli.Our results showed that most LGN cells can be evoked by second-order stimuli, and their firing rates to second-order stimuli decreased relative to first-order stimuli as temporal frequency increased from 0.5 to 8 Hz; moreover the ratio of a nonlinear to linear factor had a higher value in the responses to second-order stimuli than to first-order stimuli.We also found that the responses of Y-cells to second-order stimuli were significantly higher than the responses of X-cells, suggesting the Y-cells have a more important role in the processing of second-order stimuli.All these results reveal that first-order and second-order signals might be processed in separate 'streams' of the visual system.

  2. Context and Pavlovian conditioning.

    Science.gov (United States)

    Landeira-Fernandez, J

    1996-02-01

    Procedurally, learning has to occur in a context. Several lines of evidence suggest that contextual stimuli actively affect learning and expression of the conditional response. The experimental context can become associated with the unconditional stimulus (US), especially when the US is presented in a context in the absence of a discrete conditional stimulus (CS). Moreover, context can modulate CS-US associations. Finally, it appears that context can become associated with the CS when it is presented before the CS-US training. The purpose of the present paper is to review some of the relevant literature that considers the context as an important feature of Pavlovian conditioning and to discuss some of the main learning theories that incorporate the context into their theoretical framework. The paper starts by mentioning historical positions that considered context an important variable in conditioning and then describes how the approach to contextual conditioning changed with the modern study of Pavlovian conditioning. Various forms of measurement of context conditioning are presented and the associative strength attached to context in several experimental paradigms is examined. The possible functions that context may acquire during conditioning are pointed out and related to major learning theories. Moreover, the effect of certain neurological manipulations on context conditioning is presented and these results are discussed in terms of possible functions that the context might acquire during Pavlovian conditioning. It is concluded that contextual stimuli acquire different functions during normal conditioning. A procedure in which animals are exposed to an aversive US immediately after they are placed in the experimental context is suggested as a useful control for the study of context conditioning.

  3. Performing a secondary executive task with affective stimuli interferes with decision making under risk conditions.

    Science.gov (United States)

    Gathmann, Bettina; Pawlikowski, Mirko; Schöler, Tobias; Brand, Matthias

    2014-05-01

    Previous studies demonstrated that executive functions are crucial for advantageous decision making under risk and that therefore decision making is disrupted when working memory capacity is demanded while working on a decision task. While some studies also showed that emotions can affect decision making under risk, it is unclear how affective processing and executive functions predict decision-making performance in interaction. The current experimental study used a between-subjects design to examine whether affective pictures (positive and negative pictures compared to neutral pictures), included in a parallel executive task (working memory 2-back task), have an impact on decision making under risk as assessed by the Game of Dice Task (GDT). Moreover, the performance GDT plus 2-back task was compared to the performance in the GDT without any additional task (GDT solely). The results show that the performance in the GDT differed between groups (positive, negative, neutral, and GDT solely). The groups with affective pictures, especially those with positive pictures in the 2-back task, showed more disadvantageous decisions in the GDT than the groups with neutral pictures and the group performing the GDT without any additional task. However, executive functions moderated the effect of the affective pictures. Regardless of affective influence, subjects with good executive functions performed advantageously in the GDT. These findings support the assumption that executive functions and emotional processing interact in predicting decision making under risk.

  4. Stress effects on working memory, explicit memory, and implicit memory for neutral and emotional stimuli in healthy men

    OpenAIRE

    Mathias Luethi; Beat Meier; Carmen Sandi

    2009-01-01

    Stress is a strong modulator of memory function. However, memory is not a unitary process and stress seems to exert different effects depending on the memory type under study. Here, we explored the impact of social stress on different aspects of human memory, including tests for explicit memory and working memory (for neutral materials), as well as implicit memory (perceptual priming, contextual priming and classical conditioning for emotional stimuli). A total of 35 young adult...

  5. Use of a Remote Eye-Tracker for the Analysis of Gaze during Treadmill Walking and Visual Stimuli Exposition

    OpenAIRE

    Serchi, V.; Peruzzi, A; A. Cereatti; Della Croce, U.

    2016-01-01

    The knowledge of the visual strategies adopted while walking in cognitively engaging environments is extremely valuable. Analyzing gaze when a treadmill and a virtual reality environment are used as motor rehabilitation tools is therefore critical. Being completely unobtrusive, remote eye-trackers are the most appropriate way to measure the point of gaze. Still, the point of gaze measurements are affected by experimental conditions such as head range of motion and visual stimuli. This study a...

  6. Startle stimuli exert opposite effects on human cortical and spinal motor system excitability in leg muscles

    DEFF Research Database (Denmark)

    Ilic, T V; Pötter-Nerger, M; Holler, I

    2011-01-01

    Increased excitability of the spinal motor system has been observed after loud and unexpected acoustic stimuli (AS) preceding H-reflexes. The paradigm has been proposed as an electrophysiological marker of reticulospinal tract activity in humans. The brainstem reticular formation also maintains...... (ISI) varied between 20 to 160 ms. When given alone, the test stimulus evoked a MEP amplitude of approximately 0.5 mV in the slightly preinervated soleus muscle (SOL). In the second experiment, the startling AS was used to condition the size of the H-reflex in SOL muscle. Mean MEP amplitude...... was calculated for each ISI. The conditioning AS suppressed MEP amplitude at ISIs of 30-80 ms. By contrast, H-reflex amplitude was augmented at ISIs of 100-200 ms. In conclusions, acoustic stimulation exerts opposite and ISI-specific effects on the amplitude of MEPs and H-reflex in the SOL muscle, indicating...

  7. Freezing Behavior as a Response to Sexual Visual Stimuli as Demonstrated by Posturography

    Science.gov (United States)

    Mouras, Harold; Lelard, Thierry; Ahmaidi, Said; Godefroy, Olivier; Krystkowiak, Pierre

    2015-01-01

    Posturographic changes in motivational conditions remain largely unexplored in the context of embodied cognition. Over the last decade, sexual motivation has been used as a good canonical working model to study motivated social interactions. The objective of this study was to explore posturographic variations in response to visual sexual videos as compared to neutral videos. Our results support demonstration of a freezing-type response in response to sexually explicit stimuli compared to other conditions, as demonstrated by significantly decreased standard deviations for (i) the center of pressure displacement along the mediolateral and anteroposterior axes and (ii) center of pressure’s displacement surface. These results support the complexity of the motor correlates of sexual motivation considered to be a canonical functional context to study the motor correlates of motivated social interactions. PMID:25992571

  8. United we sense, divided we fail: context-driven perception of ambiguous visual stimuli

    NARCIS (Netherlands)

    Klink, P. C; van Wezel, Richard Jack Anton; van Ee, R.

    2012-01-01

    Ambiguous visual stimuli provide the brain with sensory information that contains conflicting evidence for multiple mutually exclusive interpretations. Two distinct aspects of the phenomenological experience associated with viewing ambiguous visual stimuli are the apparent stability of perception

  9. A dual-stimuli-responsive fluorescent switch ultrathin film

    Science.gov (United States)

    Li, Zhixiong; Liang, Ruizheng; Liu, Wendi; Yan, Dongpeng; Wei, Min

    2015-10-01

    Stimuli-responsive fluorescent switches have shown broad applications in optical devices, biological materials and intelligent responses. Herein, we describe the design and fabrication of a dual-stimuli-responsive fluorescent switch ultrathin film (UTF) via a three-step layer-by-layer (LBL) technique: (i) encapsulation of spiropyran (SP) within an amphiphilic block copolymer (PTBEM) to give the (SP@PTBEM) micelle; (ii) the mixture of riboflavin (Rf) and poly(styrene 4-sulfonate) (PSS) to enhance the adhesion ability of small molecules; (iii) assembly of negatively charged SP@PTBEM and Rf-PSS with cationic layered double hydroxide (LDH) nanoplatelets to obtain the (Rf-PSS/LDH/SP@PTBEM)n UTFs (n: bilayer number). The assembly process of the UTFs and their luminescence properties, as monitored by fluorescence spectroscopy and scanning electron microscopy (SEM), present a uniform and ordered layered structure with stepwise growth. The resulting Rf-PSS/LDH/SP@PTBEM UTF serves as a three-state switchable multicolor (green, yellow, and red) luminescent system based on stimulation from UV/Vis light and pH, with an acceptable reversibility. Therefore, this work provides a facile way to fabricate stimuli-responsive solid-state film switches with tunable-color luminescence, which have potential applications in the areas of displays, sensors, and rewritable optical memory and fluorescent logic devices.Stimuli-responsive fluorescent switches have shown broad applications in optical devices, biological materials and intelligent responses. Herein, we describe the design and fabrication of a dual-stimuli-responsive fluorescent switch ultrathin film (UTF) via a three-step layer-by-layer (LBL) technique: (i) encapsulation of spiropyran (SP) within an amphiphilic block copolymer (PTBEM) to give the (SP@PTBEM) micelle; (ii) the mixture of riboflavin (Rf) and poly(styrene 4-sulfonate) (PSS) to enhance the adhesion ability of small molecules; (iii) assembly of negatively charged SP

  10. Cell volume-regulated cation channels.

    Science.gov (United States)

    Wehner, Frank

    2006-01-01

    perception of a variety of different stimuli including mechanical and (hypo-) osmotic stress. As a peculiarity, phospholemman (PLM, a 72 AA peptide also employed in ion transport regulation) appears to be activated under, both, hypertonic and hypotonic conditions, preferentially operating as a cation and anion channel, respectively.

  11. Regional brain responses in nulliparous women to emotional infant stimuli.

    Directory of Open Access Journals (Sweden)

    Jessica L Montoya

    Full Text Available Infant cries and facial expressions influence social interactions and elicit caretaking behaviors from adults. Recent neuroimaging studies suggest that neural responses to infant stimuli involve brain regions that process rewards. However, these studies have yet to investigate individual differences in tendencies to engage or withdraw from motivationally relevant stimuli. To investigate this, we used event-related fMRI to scan 17 nulliparous women. Participants were presented with novel infant cries of two distress levels (low and high and unknown infant faces of varying affect (happy, sad, and neutral in a randomized, counter-balanced order. Brain activation was subsequently correlated with scores on the Behavioral Inhibition System/Behavioral Activation System scale. Infant cries activated bilateral superior and middle temporal gyri (STG and MTG and precentral and postcentral gyri. Activation was greater in bilateral temporal cortices for low- relative to high-distress cries. Happy relative to neutral faces activated the ventral striatum, caudate, ventromedial prefrontal, and orbitofrontal cortices. Sad versus neutral faces activated the precuneus, cuneus, and posterior cingulate cortex, and behavioral activation drive correlated with occipital cortical activations in this contrast. Behavioral inhibition correlated with activation in the right STG for high- and low-distress cries relative to pink noise. Behavioral drive correlated inversely with putamen, caudate, and thalamic activations for the comparison of high-distress cries to pink noise. Reward-responsiveness correlated with activation in the left precentral gyrus during the perception of low-distress cries relative to pink noise. Our findings indicate that infant cry stimuli elicit activations in areas implicated in auditory processing and social cognition. Happy infant faces may be encoded as rewarding, whereas sad faces activate regions associated with empathic processing. Differences

  12. Impact of emotion on consciousness: positive stimuli enhance conscious reportability.

    Directory of Open Access Journals (Sweden)

    Kristine Rømer Thomsen

    Full Text Available Emotion and reward have been proposed to be closely linked to conscious experience, but empirical data are lacking. The anterior cingulate cortex (ACC plays a central role in the hedonic dimension of conscious experience; thus potentially a key region in interactions between emotion and consciousness. Here we tested the impact of emotion on conscious experience, and directly investigated the role of the ACC. We used a masked paradigm that measures conscious reportability in terms of subjective confidence and objective accuracy in identifying the briefly presented stimulus in a forced-choice test. By manipulating the emotional valence (positive, neutral, negative and the presentation time (16 ms, 32 ms, 80 ms we measured the impact of these variables on conscious and subliminal (i.e. below threshold processing. First, we tested normal participants using face and word stimuli. Results showed that participants were more confident and accurate when consciously seeing happy versus sad/neutral faces and words. When stimuli were presented subliminally, we found no effect of emotion. To investigate the neural basis of this impact of emotion, we recorded local field potentials (LFPs directly in the ACC in a chronic pain patient. Behavioural findings were replicated: the patient was more confident and accurate when (consciously seeing happy versus sad faces, while no effect was seen in subliminal trials. Mirroring behavioural findings, we found significant differences in the LFPs after around 500 ms (lasting 30 ms in conscious trials between happy and sad faces, while no effect was found in subliminal trials. We thus demonstrate a striking impact of emotion on conscious experience, with positive emotional stimuli enhancing conscious reportability. In line with previous studies, the data indicate a key role of the ACC, but goes beyond earlier work by providing the first direct evidence of interaction between emotion and conscious experience in the human

  13. [The Contribution of the Orbitofrontal Cortex to the Preference for Visual Stimuli].

    Science.gov (United States)

    Funahashi, Shintaro

    2015-06-01

    Both humans and animals like to watch neutral and biologically insignificant visual stimuli. Behavioral studies have revealed that animals more frequently select stimuli with symmetrical and regular patterns and short movies compared to stimuli with unsymmetrical and irregular patterns and photographs. Preferred visual stimuli can serve as rewards for animals performing behavioral tasks. Preferences for visual stimuli are determined by the magnitude of the pleasant feelings that are experienced when the stimuli are seen. The orbitofrontal cortex is known to participate in the detection and prediction of reward, the estimation of the value of the stimuli as a reward, and positive emotion. Human neuroimaging studies and animal neurophysiological studies have shown that the magnitude of orbitofrontal responses to the presentation of neutral visual stimuli correlates with the strength of the preference for the stimuli in the behavioral studies. These results suggest that the magnitude of orbitofrontal responses to the visual stimuli correlates with the strength of the pleasant feelings that are produced by the stimuli and that the orbitofrontal cortex plays an important role in the judgment of the preference for visual stimuli.

  14. Ribozymes that can be regulated by external stimuli.

    Science.gov (United States)

    Frommer, Jennifer; Appel, Bettina; Müller, Sabine

    2015-02-01

    Ribozymes have been known for about 30 years, and nowadays are understood well enough to be turned into useful tools for a number of applications in vitro and in vivo. Allosteric ribozymes switch on and off their activity in response to a specific chemical (ligand) or physical (temperature, light) signal. The possibility of controlling ribozyme activity by external stimuli is of particular relevance for applications in different fields, such as environmental and medicinal diagnostics, molecular computing, control of gene expression and others. Herein, we review recent advances and describe selected examples of addressable ribozymes. Copyright © 2014 Elsevier Ltd. All rights reserved.

  15. Construction of Hindi Speech Stimuli for Eliciting Auditory Brainstem Responses.

    Science.gov (United States)

    Ansari, Mohammad Shamim; Rangasayee, R

    2016-12-01

    Speech-evoked auditory brainstem responses (spABRs) provide considerable information of clinical relevance to describe auditory processing of complex stimuli at the sub cortical level. The substantial research data have suggested faithful representation of temporal and spectral characteristics of speech sounds. However, the spABR are known to be affected by acoustic properties of speech, language experiences and training. Hence, there exists indecisive literature with regards to brainstem speech processing. This warrants establishment of language specific speech stimulus to describe the brainstem processing in specific oral language user. The objective of current study is to develop Hindi speech stimuli for recording auditory brainstem responses. The Hindi stop speech of 40 ms containing five formants was constructed. Brainstem evoked responses to speech sound |da| were gained from 25 normal hearing (NH) adults having mean age of 20.9 years (SD = 2.7) in the age range of 18-25 years and ten subjects (HI) with mild SNHL of mean 21.3 years (SD = 3.2) in the age range of 18-25 years. The statistically significant differences in the mean identification scores of synthesized for speech stimuli |da| and |ga| between NH and HI were obtained. The mean, median, standard deviation, minimum, maximum and 95 % confidence interval for the discrete peaks and V-A complex values of electrophysiological responses to speech stimulus were measured and compared between NH and HI population. This paper delineates a comprehensive methodological approach for development of Hindi speech stimuli and recording of ABR to speech. The acoustic characteristic of stimulus |da| was faithfully represented at brainstem level in normal hearing adults. There was statistically significance difference between NH and HI individuals. This suggests that spABR offers an opportunity to segregate normal speech encoding from abnormal speech processing at sub cortical level, which implies that

  16. Predicting the threshold of pulse-train electrical stimuli using a stochastic auditory nerve model: the effects of stimulus noise.

    Science.gov (United States)

    Xu, Yifang; Collins, Leslie M

    2004-04-01

    The incorporation of low levels of noise into an electrical stimulus has been shown to improve auditory thresholds in some human subjects (Zeng et al., 2000). In this paper, thresholds for noise-modulated pulse-train stimuli are predicted utilizing a stochastic neural-behavioral model of ensemble fiber responses to bi-phasic stimuli. The neural refractory effect is described using a Markov model for a noise-free pulse-train stimulus and a closed-form solution for the steady-state neural response is provided. For noise-modulated pulse-train stimuli, a recursive method using the conditional probability is utilized to track the neural responses to each successive pulse. A neural spike count rule has been presented for both threshold and intensity discrimination under the assumption that auditory perception occurs via integration over a relatively long time period (Bruce et al., 1999). An alternative approach originates from the hypothesis of the multilook model (Viemeister and Wakefield, 1991), which argues that auditory perception is based on several shorter time integrations and may suggest an NofM model for prediction of pulse-train threshold. This motivates analyzing the neural response to each individual pulse within a pulse train, which is considered to be the brief look. A logarithmic rule is hypothesized for pulse-train threshold. Predictions from the multilook model are shown to match trends in psychophysical data for noise-free stimuli that are not always matched by the long-time integration rule. Theoretical predictions indicate that threshold decreases as noise variance increases. Theoretical models of the neural response to pulse-train stimuli not only reduce calculational overhead but also facilitate utilization of signal detection theory and are easily extended to multichannel psychophysical tasks.

  17. Biasing the development of response topography with nonspecific positive and negative evocative verbal stimuli.

    Science.gov (United States)

    Cody, W J; Grant, D A

    1978-03-01

    Conditioned response (CR) rate and development of CR latency, rise time, and airpuff attenuation were examined for V- and C-form responders using two nonspecific command words, do and don't, as conditioned stimuli (CSs) in single-cue, double-cue, and differential eyelid conditioning. In both single-cue and differential conditioning, regardless of the command word used to signal the unconditioned stimulus (UCS), the Vs produced a higher response rate and learned a better UCS-attenuating response topography than the Cs. However, in a double-cue conditioning paradigm in which both command words were presented alone on different trials and reinforced, response latency was longer and puff attenuation poorer among Vs than when the UCS was signaled by a unique cue. In contrast, adding a second reinforced cue actually enhanced the development of puff-avoidant CR topographies among Cs compared to single-cue conditioning. These results and others indicate that response topography development is to some extent a labile process that can be biased toward either good or poor puff-avoidant properties and that the factors responsible for influencing CR topography differ for Vs and Cs.

  18. Predictive Physiological Anticipation Preceding Seemingly Unpredictable Stimuli:A Meta-Analysis

    Directory of Open Access Journals (Sweden)

    Julia eMossbridge

    2012-10-01

    Full Text Available This meta-analysis of 26 reports published between 1978 and 2010 tests an unusal hypothesis: for stimuli of two or more types that are presented in an order designed to be unpredictable and that produce different post-stimulus physiological activity, the direction of pre-stimulus physiological activity reflects the direction of post-stimulus physiological activity, resulting in an unexplained anticipatory effect. The reports we examined used one of two paradigms: 1 randomly presented arousing vs. neutral stimuli, or 2 guessing tasks with feedback (correct vs. incorrect. Dependent variables included: electrodermal activity, heart rate, blood volume, pupil dilation, electroencephalographic activity (EEG, and blood oxygenation level dependent (BOLD activity. To avoid including data hand-picked from multiple different analyses, no post-hoc experiments are considered. The results reveal a significant overall effect with a small effect size (random effects: overall [weighted] ES=0.21, 95%CI=0.13-0.29, z=5.3, p<5.7x10-8; fixed effects: overall ES=0.21, 95%CI=0.15-0.27, z=6.9, p<2.7x10-12. Higher quality experiments produce a quantitately larger effect size and a greater level of significance than lower quality studies. The number of contrary unpublished reports that would be necessary to reduce the level of significance to chance (p>0.05 was conservatively calculated to be 87 reports. We explore alternative explanations and examine the potential linkage between this unexplained anticipatory activity and other results demonstrating meaningful pre-stimulus activity preceding behaviourally relevant events. Multiple replications arising from different laboratories using the same methods are necessary to further examine this currently unexplained anticipatory activity. The cause of this anticipatory activity, which undoubtedly lies within the realm of natural physical processes (as opposed to supernatural or paranormal ones, remains to be determined.

  19. The simultaneous perception of auditory–tactile stimuli in voluntary movement

    Directory of Open Access Journals (Sweden)

    Qiao eHao

    2015-09-01

    Full Text Available The simultaneous perception of multimodal information in the environment during voluntary movement is very important for effective reactions to the environment. Previous studies have found that voluntary movement affects the simultaneous perception of auditory and tactile stimuli. However, the results of these experiments are not completely consistent, and the differences may be attributable to methodological differences in the previous studies. In this study, we investigated the effect of voluntary movement on the simultaneous perception of auditory and tactile stimuli using a temporal order judgment task with voluntary movement, involuntary movement, and no movement. To eliminate the potential effect of stimulus predictability and the effect of spatial information associated with large-scale movement in the previous studies, we randomized the interval between the start of movement and the first stimulus, and used small-scale movement. As a result, the point of subjective simultaneity (PSS during voluntary movement shifted from the tactile stimulus being first during involuntary movement or no movement to the auditory stimulus being first. The just noticeable difference (JND, an indicator of temporal resolution, did not differ across the three conditions. These results indicate that voluntary movement itself affects the PSS in auditory–tactile simultaneous perception, but it does not influence the JND. In the discussion of these results, we suggest that simultaneous perception may be affected by the efference copy.

  20. Faithful representation of stimuli with a population of integrate-and-fire neurons.

    Science.gov (United States)

    Lazar, Aurel A; Pnevmatikakis, Eftychios A

    2008-11-01

    We consider a formal model of stimulus encoding with a circuit consisting of a bank of filters and an ensemble of integrate-and-fire neurons. Such models arise in olfactory systems, vision, and hearing. We demonstrate that bandlimited stimuli can be faithfully represented with spike trains generated by the ensemble of neurons. We provide a stimulus reconstruction scheme based on the spike times of the ensemble of neurons and derive conditions for perfect recovery. The key result calls for the spike density of the neural population to be above the Nyquist rate. We also show that recovery is perfect if the number of neurons in the population is larger than a threshold value. Increasing the number of neurons to achieve a faithful representation of the sensory world is consistent with basic neurobiological thought. Finally we demonstrate that in general, the problem of faithful recovery of stimuli from the spike train of single neurons is ill posed. The stimulus can be recovered, however, from the information contained in the spike train of a population of neurons.

  1. Differential activation of the dorsal striatum by high-calorie visual food stimuli in obese individuals.

    Science.gov (United States)

    Rothemund, Yvonne; Preuschhof, Claudia; Bohner, Georg; Bauknecht, Hans-Christian; Klingebiel, Randolf; Flor, Herta; Klapp, Burghard F

    2007-08-15

    The neural systems regulating food intake in obese individuals remain poorly understood. Previous studies applied positron emission tomography and manipulated hunger and satiety to investigate differences in appetitive processing between obese and normal-weight individuals. However, it is not known whether manipulation of stimulus value may yield different neural activity in obese as compared to control subjects when intrinsic physiological states are kept constant. We used functional magnetic resonance imaging to investigate 13 obese and 13 normal-weight subjects and manipulated food motivation by presenting visual food stimuli differing in their caloric content and energy density. In contrast to controls, obese women selectively activated the dorsal striatum while viewing high-caloric foods. Moreover, in the high-calorie condition body mass index (BMI) predicted activation in the dorsal striatum, anterior insula, claustrum, posterior cingulate, postcentral and lateral orbitofrontal cortex. The results indicate that in obese individuals simple visual stimulation with food stimuli activates regions related to reward anticipation and habit learning (dorsal striatum). Additionally, high-calorie food images yielded BMI-dependent activations in regions associated with taste information processing (anterior insula and lateral orbitofrontal cortex), motivation (orbitofrontal cortex), emotion as well as memory functions (posterior cingulate). Collectively, the results suggest that the observed activation is independent of the physiological states of hunger and satiation, and thus may contribute to pathological overeating and obesity. Some of the observed activations (dorsal striatum, orbitofrontal cortex) are likely to be dopamine-mediated.

  2. Exposure to salient, dynamic sensory stimuli during development increases distractibility in adulthood.

    Science.gov (United States)

    Hadas, Itay; Gal, Ram; Bokovza, Lihi; Meiran, Nachshon; Feifel, David; Zangen, Abraham

    2016-02-17

    It has been suggested that excessive exposure of children to the dynamic and highly salient audio-visual stimuli conveyed by electronic media may induce attention-related deficits in adulthood. This study was designed to evaluate this hypothesis in a controlled animal model setup. Building on their natural responsiveness to odors, we exposed juvenile rats for 1 h daily to a dynamic series of interchanging, highly salient odors, while controls were exposed to a non-changing mixture of these odors. Upon reaching adulthood, we tested the attentional capacity of the rats and measured their brain-derived neurotrophic factor (BDNF) levels as a proxy of neuronal plasticity. As compared with controls, rats exposed to the dynamic stimulation showed no attentional deficits under baseline task conditions, but their performance was dramatically impaired when an auditory distractor was introduced in the task. In addition, BDNF levels in the dorsal striatum of these rats were significantly increased relative to controls. These findings provide first empirical evidence that a continuous exposure to dynamic, highly salient stimuli has long-term effects on attentional functions later in life, and that these effects may have neural correlates in the dorsal striatum.

  3. Gaming to see: Action Video Gaming is associated with enhanced processing of masked stimuli

    Directory of Open Access Journals (Sweden)

    Carsten ePohl

    2014-02-01

    Full Text Available Recent research revealed that action video game players outperform non-players in a wide range of attentional, perceptual and cognitive tasks. Here we tested if expertise in action video games is related to differences regarding the potential of shortly presented stimuli to bias behaviour. In a response priming paradigm, participants classified four animal pictures functioning as targets as being smaller or larger than a reference frame. Before each target, one of the same four animal pictures was presented as a masked prime to influence participants’ responses in a congruent or incongruent way. Masked primes induced congruence effects, that is, faster responses for congruent compared to incongruent conditions, indicating processing of hardly visible primes. Results also suggested that action video game players showed a larger congruence effect than non-players for 20 ms primes, whereas there was no group difference for 60 ms primes. In addition, there was a tendency for action video game players to detect masked primes for some prime durations better than non-players. Thus, action video game expertise may be accompanied by faster and more efficient processing of shortly presented visual stimuli.

  4. Gaming to see: action video gaming is associated with enhanced processing of masked stimuli.

    Science.gov (United States)

    Pohl, Carsten; Kunde, Wilfried; Ganz, Thomas; Conzelmann, Annette; Pauli, Paul; Kiesel, Andrea

    2014-01-01

    Recent research revealed that action video game players outperform non-players in a wide range of attentional, perceptual and cognitive tasks. Here we tested if expertise in action video games is related to differences regarding the potential of shortly presented stimuli to bias behavior. In a response priming paradigm, participants classified four animal pictures functioning as targets as being smaller or larger than a reference frame. Before each target, one of the same four animal pictures was presented as a masked prime to influence participants' responses in a congruent or incongruent way. Masked primes induced congruence effects, that is, faster responses for congruent compared to incongruent conditions, indicating processing of hardly visible primes. Results also suggested that action video game players showed a larger congruence effect than non-players for 20 ms primes, whereas there was no group difference for 60 ms primes. In addition, there was a tendency for action video game players to detect masked primes for some prime durations better than non-players. Thus, action video game expertise may be accompanied by faster and more efficient processing of shortly presented visual stimuli.

  5. Block randomization versus complete randomization of human perception stimuli: is there a difference?

    Science.gov (United States)

    Moyer, Steve; Uhl, Elizabeth R.

    2015-05-01

    For more than 50 years, the U.S. Army RDECOM CERDEC Night Vision and Electronic Sensors Directorate (NVESD) has been studying and modeling the human visual discrimination process as it pertains to military imaging systems. In order to develop sensor performance models, human observers are trained to expert levels in the identification of military vehicles. From 1998 until 2006, the experimental stimuli were block randomized, meaning that stimuli with similar difficulty levels (for example, in terms of distance from target, blur, noise, etc.) were presented together in blocks of approximately 24 images but the order of images within the block was random. Starting in 2006, complete randomization came into vogue, meaning that difficulty could change image to image. It was thought that this would provide a more statistically robust result. In this study we investigated the impact of the two types of randomization on performance in two groups of observers matched for skill to create equivalent groups. It is hypothesized that Soldiers in the Complete Randomized condition will have to shift their decision criterion more frequently than Soldiers in the Block Randomization group and this shifting is expected to impede performance so that Soldiers in the Block Randomized group perform better.

  6. Context preexposure influences the effectiveness of feedback stimuli in avoidance learning.

    Science.gov (United States)

    Callen, Edward J

    2004-04-30

    According to the effective reinforcement theory of avoidance learning, there is a positive relationship between the level of context fear and the effectiveness of feedback stimuli. The present research used different preexposure treatments to manipulate context fear and to evaluate the effects of feedback stimuli in two-way avoidance learning. Rat subjects received nonreinforced preexposure either to the nonvisual context cues (avoidance apparatus with the houselights extinguished), to the visual context cues (avoidance apparatus with the houselights on but with a Plexiglas floor covering the grids), or to a neutral box. During subsequent avoidance training conditioned stimulus termination was delayed for 5s after an instrumental response and either a flashing light or darkness was presented as a feedback stimulus. Without preexposure, darkness produced better avoidance performance than did the flashing light. Preexposure to the visual context cues decreased the effectiveness of darkness as a feedback stimulus. However, preexposure to either the visual or to the nonvisual context cues facilitated avoidance performance when a flashing light was used as a feedback stimulus. The results suggest that the effects of a feedback stimulus may be dependent upon the amount and source of context fear.

  7. The simultaneous perception of auditory-tactile stimuli in voluntary movement.

    Science.gov (United States)

    Hao, Qiao; Ogata, Taiki; Ogawa, Ken-Ichiro; Kwon, Jinhwan; Miyake, Yoshihiro

    2015-01-01

    The simultaneous perception of multimodal information in the environment during voluntary movement is very important for effective reactions to the environment. Previous studies have found that voluntary movement affects the simultaneous perception of auditory and tactile stimuli. However, the results of these experiments are not completely consistent, and the differences may be attributable to methodological differences in the previous studies. In this study, we investigated the effect of voluntary movement on the simultaneous perception of auditory and tactile stimuli using a temporal order judgment task with voluntary movement, involuntary movement, and no movement. To eliminate the potential effect of stimulus predictability and the effect of spatial information associated with large-scale movement in the previous studies, we randomized the interval between the start of movement and the first stimulus, and used small-scale movement. As a result, the point of subjective simultaneity (PSS) during voluntary movement shifted from the tactile stimulus being first during involuntary movement or no movement to the auditory stimulus being first. The just noticeable difference (JND), an indicator of temporal resolution, did not differ across the three conditions. These results indicate that voluntary movement itself affects the PSS in auditory-tactile simultaneous perception, but it does not influence the JND. In the discussion of these results, we suggest that simultaneous perception may be affected by the efference copy.

  8. The simultaneous perception of auditory–tactile stimuli in voluntary movement

    Science.gov (United States)

    Hao, Qiao; Ogata, Taiki; Ogawa, Ken-ichiro; Kwon, Jinhwan; Miyake, Yoshihiro

    2015-01-01

    The simultaneous perception of multimodal information in the environment during voluntary movement is very important for effective reactions to the environment. Previous studies have found that voluntary movement affects the simultaneous perception of auditory and tactile stimuli. However, the results of these experiments are not completely consistent, and the differences may be attributable to methodological differences in the previous studies. In this study, we investigated the effect of voluntary movement on the simultaneous perception of auditory and tactile stimuli using a temporal order judgment task with voluntary movement, involuntary movement, and no movement. To eliminate the potential effect of stimulus predictability and the effect of spatial information associated with large-scale movement in the previous studies, we randomized the interval between the start of movement and the first stimulus, and used small-scale movement. As a result, the point of subjective simultaneity (PSS) during voluntary movement shifted from the tactile stimulus being first during involuntary movement or no movement to the auditory stimulus being first. The just noticeable difference (JND), an indicator of temporal resolution, did not differ across the three conditions. These results indicate that voluntary movement itself affects the PSS in auditory–tactile simultaneous perception, but it does not influence the JND. In the discussion of these results, we suggest that simultaneous perception may be affected by the efference copy. PMID:26441799

  9. Response Preparation, Response Conflict, and the Effects of Irrelevant Flanker Stimuli.

    Science.gov (United States)

    Wühr, Peter; Heuer, Herbert

    2017-01-01

    The present study explored how response preparation modulates the effects of response conflict as induced by irrelevant flanker stimuli. In Experiments 1 and 2, an unreliable response cue (i.e., valid in 75% of trials but invalid in 25% of trials) preceded the stimulus display containing a target stimulus and different types (i.e., identical, neutral, compatible, or incompatible) flanker stimuli. In Experiment 3, a fully reliable response cue (i.e., valid in 100% of trials) or a neutral cue preceded the stimulus display. There were two major findings. First, valid response cues always improved performance in terms of speed and accuracy when compared to invalid or neutral cues, indicating that the cues were used to selectively prepare the indicated response. Second, response preparation with unreliable response cues did not modulate flanker-induced response conflict in reaction times (RTs; and not consistently in error percentages), whereas response preparation with reliable cues eliminated flanker-induced response conflict. According to these results, only extreme levels of response preparation modulate (flanker-induced) response conflict. The results of computer simulations suggest some boundary conditions for our conclusion.

  10. Changes in the Influence of Alcohol-Paired Stimuli on Alcohol Seeking across Extended Training

    Science.gov (United States)

    Corbit, Laura H.; Janak, Patricia H.

    2016-01-01

    Previous work has demonstrated that goal-directed control of alcohol-seeking and other drug-related behaviors is reduced following extended self-administration and drug exposure. Here, we examined how the magnitude of stimulus influences on responding changes across similar training and drug exposure. Rats self-administered alcohol or sucrose for 2 or 8 weeks. Previous work has shown that 8 weeks, but not 2 weeks of self-administration produces habitual alcohol seeking. Next, all animals received equivalent Pavlovian conditioning sessions where a discrete stimulus predicted the delivery of alcohol or sucrose. Finally, the impact of the stimuli on ongoing instrumental responding was examined in a Pavlovian–instrumental transfer (PIT) test. While a significant PIT effect was observed following 2 weeks of either alcohol or sucrose self-administration, the magnitude of this effect was greater following 8 weeks of training. The specificity of the PIT effect appeared unchanged by extended training. While it is well established that evaluation of the outcome of responding contributes less to behavioral control following extended training and/or drug exposure, our data indicate that reward–predictive stimuli have a stronger contribution to responding after extended training. Together, these findings provide insight into the factors that control behavior after extended drug use, which will be important for developing effective methods for controlling and ideally reducing these behaviors. PMID:27777560

  11. Distinct acute zones for visual stimuli in different visual tasks in Drosophila.

    Directory of Open Access Journals (Sweden)

    Xing Yang

    Full Text Available The fruit fly Drosophila melanogaster has a sophisticated visual system and exhibits complex visual behaviors. Visual responses, vision processing and higher cognitive processes in Drosophila have been studied extensively. However, little is known about whether the retinal location of visual stimuli can affect fruit fly performance in various visual tasks. We tested the response of wild-type Berlin flies to visual stimuli at several vertical locations. Three paradigms were used in our study: visual operant conditioning, visual object fixation and optomotor response. We observed an acute zone for visual feature memorization in the upper visual field when visual patterns were presented with a black background. However, when a white background was used, the acute zone was in the lower visual field. Similar to visual feature memorization, the best locations for visual object fixation and optomotor response to a single moving stripe were in the lower visual field with a white background and the upper visual field with a black background. The preferred location for the optomotor response to moving gratings was around the equator of the visual field. Our results suggest that different visual processing pathways are involved in different visual tasks and that there is a certain degree of overlap between the pathways for visual feature memorization, visual object fixation and optomotor response.

  12. Large crowding zones in peripheral vision for briefly presented stimuli.

    Science.gov (United States)

    Tripathy, Srimant Prasad; Cavanagh, Patrick; Bedell, Harold E

    2014-12-30

    When a target is flanked by distractors, it becomes more difficult to identify. In the periphery, this crowding effect extends over a wide range of target-flanker separations, called the spatial extent of interaction (EoI). A recent study showed that the EoI dramatically increases in size for short presentation durations (Chung & Mansfield, 2009). Here we investigate this duration-EoI relation in greater detail and show that (a) it holds even when visibility of the unflanked target is equated for different durations, (b) the function saturates for durations shorter than 30 to 80 ms, and (c) the largest EoIs represent a critical spacing greater than 50% of eccentricity. We also investigated the effect of same or different polarity for targets and flankers across different presentation durations. We found that EoIs for target and flankers having opposite polarity (one white, the other black) show the same temporal pattern as for same polarity stimuli, but are smaller at all durations by 29% to 44%. The observed saturation of the EoI for short-duration stimuli suggests that crowding follows the locus of temporal integration. Overall, the results constrain theories that map crowding zones to fixed spatial extents or to lateral connections of fixed length in the cortex.

  13. Representation of dynamical stimuli in populations of threshold neurons.

    Directory of Open Access Journals (Sweden)

    Tatjana Tchumatchenko

    2011-10-01

    Full Text Available Many sensory or cognitive events are associated with dynamic current modulations in cortical neurons. This raises an urgent demand for tractable model approaches addressing the merits and limits of potential encoding strategies. Yet, current theoretical approaches addressing the response to mean- and variance-encoded stimuli rarely provide complete response functions for both modes of encoding in the presence of correlated noise. Here, we investigate the neuronal population response to dynamical modifications of the mean or variance of the synaptic bombardment using an alternative threshold model framework. In the variance and mean channel, we provide explicit expressions for the linear and non-linear frequency response functions in the presence of correlated noise and use them to derive population rate response to step-like stimuli. For mean-encoded signals, we find that the complete response function depends only on the temporal width of the input correlation function, but not on other functional specifics. Furthermore, we show that both mean- and variance-encoded signals can relay high-frequency inputs, and in both schemes step-like changes can be detected instantaneously. Finally, we obtain the pairwise spike correlation function and the spike triggered average from the linear mean-evoked response function. These results provide a maximally tractable limiting case that complements and extends previous results obtained in the integrate and fire framework.

  14. Contrast polarity preservation's role in perception: explained and unexplained stimuli.

    Science.gov (United States)

    McCormick, Meghan C; Hon, Alice J; Huang, Abigail E; Altschuler, Eric L

    2012-01-01

    Roncato and Casco (2003, Perception & psychophysics 65 1252-1272) had shown that in situations where the Gestalt principle of good continuity is put into conflict with preservation of contrast polarity (CP) the perception that preserves CP prevails. Parlangeli and Roncato (2010, Perception 39 255-259) have studied this question of preservation of CP more closely and have added an addendum to the rule. They have used stimuli consisting of a checkerboard of perpendicularly arranged rectangular bricks (white, gray, or black) and draughtsmen white, gray, or black disks placed at the corners of the bricks. This study has caused them to add an addendum to the rule of CP-preserved path-conjunction binding: if there are two contour completions that preserve the CP, the one with the higher contrast will prevail. Parlangeli and Roncato find that, for certain shades of the disks and bricks, the perpendicular lines of the checkerboard appear strikingly to be slanted or undulating. Here we consider all possible arrangements of relative magnitudes of checkerboards consisting of bricks of two different shades and disks of two shades as well, as such arrangements with widely varying differences in the magnitude of brightness. We have found a number of cases where the perception is not explained by the rule and addendum of Roncato and Casco, and Parlangeli and Roncato, and a case where preservation of "distant" as well as local CP plays a role in perception. The previously known cases, and the new exceptional unexplained stimuli we have found, warrant further study.

  15. Characterization of Ferrofluid-based Stimuli-responsive Elastomers

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    Sandra dePedro

    2016-12-01

    Full Text Available Stimuli-responsive materials undergo physicochemical, and/or structural changes when a specific actuation is applied. They are heterogeneous composites, consisting of a non-responsive matrix where functionality is provided by the filler. Surprisingly, the synthesis of Polydimethylsiloxane (PDMS-based stimuli-responsive elastomers (SRE has seldomly been presented. Here we present the structural, biological, optical, magnetic and mechanical properties of several magnetic SRE (M-SRE obtained by combining PDMS and isoparafin-based ferrofluid (FF. Independently of the FF concentration, results shown a similar aggregation level, with the nanoparticles (NP mostly isolated (>60%. In addition to the superparamagnetic behaviour, the samples show no cytotoxicity except the sample with the highest FF concentration. Spectral response shows FF concentrations where both optical readout and magnetic actuation can simultaneously be used. The Young’s modulus increases with the FF concentration until the elastomeric network is distorted. Our results demonstrate that PDMS can host up to 24.6% FF. When applied to soft microsystems, a large displacement for relatively low magnetic fields (< 0.3 T is achieved. The herein presented M-SRE characterization can be used for a large number of disciplines where magnetic actuation can be combined with optical detection, mechanical elements and biological samples.

  16. Music Influences Ratings of the Affect of Visual Stimuli

    Directory of Open Access Journals (Sweden)

    Waldie E Hanser

    2013-09-01

    Full Text Available This review provides an overview of recent studies that have examined how music influences the judgment of emotional stimuli, including affective pictures and film clips. The relevant findings are incorporated within a broader theory of music and emotion, and suggestions for future research are offered.Music is important in our daily lives, and one of its primary uses by listeners is the active regulation of one's mood. Despite this widespread use as a regulator of mood and its general pervasiveness in our society, the number of studies investigating the issue of whether, and how, music affects mood and emotional behaviour is limited however. Experiments investigating the effects of music have generally focused on how the emotional valence of background music impacts how affective pictures and/or film clips are evaluated. These studies have demonstrated strong effects of music on the emotional judgment of such stimuli. Most studies have reported concurrent background music to enhance the emotional valence when music and pictures are emotionally congruent. On the other hand, when music and pictures are emotionally incongruent, the ratings of the affect of the pictures will in- or decrease depending on the emotional valence of the background music. These results appear to be consistent in studies investigating the effects of (background music.

  17. Healable thermoset polymer composite embedded with stimuli-responsive fibres.

    Science.gov (United States)

    Li, Guoqiang; Meng, Harper; Hu, Jinlian

    2012-12-07

    Severe wounds in biological systems such as human skin cannot heal themselves, unless they are first stitched together. Healing of macroscopic damage in thermoset polymer composites faces a similar challenge. Stimuli-responsive shape-changing polymeric fibres with outstanding mechanical properties embedded in polymers may be able to close macro-cracks automatically upon stimulation such as heating. Here, a stimuli-responsive fibre (SRF) with outstanding mechanical properties and supercontraction capability was fabricated for the purpose of healing macroscopic damage. The SRFs and thermoplastic particles (TPs) were incorporated into regular thermosetting epoxy for repeatedly healing macroscopic damages. The system works by mimicking self-healing of biological systems such as human skin, close (stitch) then heal, i.e. close the macroscopic crack through the thermal-induced supercontraction of the SRFs, and bond the closed crack through melting and diffusing of TPs at the crack interface. The healing efficiency determined using tapered double-cantilever beam specimens was 94 per cent. The self-healing process was reasonably repeatable.

  18. Crosslinked ionic polysaccharides for stimuli-sensitive drug delivery.

    Science.gov (United States)

    Alvarez-Lorenzo, Carmen; Blanco-Fernandez, Barbara; Puga, Ana M; Concheiro, Angel

    2013-08-01

    Polysaccharides are gaining increasing attention as components of stimuli-responsive drug delivery systems, particularly since they can be obtained in a well characterized and reproducible way from the natural sources. Ionic polysaccharides can be readily crosslinked to render hydrogel networks sensitive to a variety of internal and external variables, and thus suitable for switching drug release on-off through diverse mechanisms. Hybrids, composites and grafted polymers can reinforce the responsiveness and widen the range of stimuli to which polysaccharide-based systems can respond. This review analyzes the state of the art of crosslinked ionic polysaccharides as components of delivery systems that can regulate drug release as a function of changes in pH, ion nature and concentration, electric and magnetic field intensity, light wavelength, temperature, redox potential, and certain molecules (enzymes, illness markers, and so on). Examples of specific applications are provided. The information compiled demonstrates that crosslinked networks of ionic polysaccharides are suitable building blocks for developing advanced externally activated and feed-back modulated drug delivery systems. Copyright © 2013 Elsevier B.V. All rights reserved.

  19. Analyzing the user behavior towards Electronic Commerce stimuli

    Directory of Open Access Journals (Sweden)

    Carlota Lorenzo-Romero

    2016-11-01

    Full Text Available Based on the Stimulus-Organism-Response paradigm this research analyzes the main differences between the effects of two types of web technologies: Verbal web technology (i.e. navigational structure as utilitarian stimulus versus nonverbal web technology (music and presentation of products as hedonic stimuli. Specific webmosphere stimuli have not been examined yet as separate variables and their impact on internal and behavioral responses seems unknown. Therefore, the objective of this research consists in analyzing the impact of these web technologies –which constitute the web atmosphere or webmosphere of a website– on shopping human bebaviour (i.e. users’ internal states -affective, cognitive, and satisfaction- and behavioral responses - approach responses, and real shopping outcomes- within the retail online store created by computer, taking into account some mediator variables (i.e. involvement, atmospheric responsiveness, and perceived risk. A 2(free versus hierarchical navigational structure x2(on versus off music x2(moving versus static images between-subjects computer experimental design is used to test empirically this research. In addition, an integrated methodology was developed allowing the simulation, tracking and recording of virtual user behavior within an online shopping environment. As main conclusion, this study suggests that the positive responses of online consumers might increase when they are allowed to freely navigate the online stores and their experience is enriched by animate gifts and music background. The effect caused by mediator variables modifies relatively the final shopping human behavior.

  20. Analyzing the User Behavior toward Electronic Commerce Stimuli.

    Science.gov (United States)

    Lorenzo-Romero, Carlota; Alarcón-Del-Amo, María-Del-Carmen; Gómez-Borja, Miguel-Ángel

    2016-01-01

    Based on the Stimulus-Organism-Response paradigm this research analyzes the main differences between the effects of two types of web technologies: Verbal web technology (i.e., navigational structure as utilitarian stimulus) versus non-verbal web technology (music and presentation of products as hedonic stimuli). Specific webmosphere stimuli have not been examined yet as separate variables and their impact on internal and behavioral responses seems unknown. Therefore, the objective of this research consists in analyzing the impact of these web technologies -which constitute the web atmosphere or webmosphere of a website- on shopping human behavior (i.e., users' internal states -affective, cognitive, and satisfaction- and behavioral responses - approach responses, and real shopping outcomes-) within the retail online store created by computer, taking into account some mediator variables (i.e., involvement, atmospheric responsiveness, and perceived risk). A 2 ("free" versus "hierarchical" navigational structure) × 2 ("on" versus "off" music) × 2 ("moving" versus "static" images) between-subjects computer experimental design is used to test empirically this research. In addition, an integrated methodology was developed allowing the simulation, tracking and recording of virtual user behavior within an online shopping environment. As main conclusion, this study suggests that the positive responses of online consumers might increase when they are allowed to freely navigate the online stores and their experience is enriched by animate gifts and music background. The effect caused by mediator variables modifies relatively the final shopping human behavior.

  1. Pupillary response to direct and consensual chromatic light stimuli

    DEFF Research Database (Denmark)

    Traustason, Sindri; Brondsted, Adam Elias; Sander, Birgit

    2016-01-01

    PURPOSE: To assess whether the direct and consensual postillumination (ipRGC-driven) pupil light responses to chromatic light stimuli are equal in healthy subjects. METHODS: Pupil responses in healthy volunteers were recorded using a prototype binocular chromatic pupillometer (IdeaMedical, Copenh......PURPOSE: To assess whether the direct and consensual postillumination (ipRGC-driven) pupil light responses to chromatic light stimuli are equal in healthy subjects. METHODS: Pupil responses in healthy volunteers were recorded using a prototype binocular chromatic pupillometer (Idea......Medical, Copenhagen), which is capable of both direct and consensual pupillometry measurements. The device uses a pair of dual monochromatic narrow bandwidth LED light sources, red (660 nm) and blue (470 nm). Pupil light responses were recorded with infrared video cameras and analysed using custom-made circuitry...... was slightly larger during consensual illumination compared to direct illumination (0.54 and 0.52, respectively, p = 0.027, paired Wilcoxon's test, n = 12), while no differences were found for CAmax or the PIPR. CONCLUSIONS: No difference was found between direct and consensual pupil response to either red...

  2. Investigating vision in schizophrenia through responses to humorous stimuli

    Directory of Open Access Journals (Sweden)

    Wolfgang Tschacher

    2015-06-01

    Full Text Available The visual environment of humans contains abundant ambiguity and fragmentary information. Therefore, an early step of vision must disambiguate the incessant stream of information. Humorous stimuli produce a situation that is strikingly analogous to this process: Funniness is associated with the incongruity contained in a joke, pun, or cartoon. Like in vision in general, appreciating a visual pun as funny necessitates disambiguation of incongruous information. Therefore, perceived funniness of visual puns was implemented to study visual perception in a sample of 36 schizophrenia patients and 56 healthy control participants. We found that both visual incongruity and Theory of Mind (ToM content of the puns were associated with increased experienced funniness. This was significantly less so in participants with schizophrenia, consistent with the gestalt hypothesis of schizophrenia, which would predict compromised perceptual organization in patients. The association of incongruity with funniness was not mediated by known predictors of humor appreciation, such as affective state, depression, or extraversion. Patients with higher excitement symptoms and, at a trend level, reduced cognitive symptoms, reported lower funniness experiences. An open question remained whether patients showed this deficiency of visual incongruity detection independent of their ToM deficiency. Humorous stimuli may be viewed as a convenient method to study perceptual processes, but also fundamental questions of higher-level cognition.

  3. Moving stimuli facilitate synchronization but not temporal perception

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    Susana Silva

    2016-11-01

    Full Text Available Recent studies have shown that a moving visual stimulus (e.g., a bouncing ball facilitates synchronization compared to a static stimulus (e.g., a flashing light, and that it can even be as effective as an auditory beep. We asked a group of participants to perform different tasks with four stimulus types: beeps, siren-like sounds, visual flashes (static and bouncing balls. First, participants performed synchronization with isochronous sequences (stimulus-guided synchronization, followed by a continuation phase in which the stimulus was internally generated (imagery-guided synchronization. Then they performed a perception task, in which they judged whether the final part of a temporal sequence was compatible with the previous beat structure (stimulus-guided perception. Similar to synchronization, an imagery-guided variant was added, in which sequences contained a gap in between (imagery-guided perception. Balls outperformed flashes and matched beeps (powerful ball effect in stimulus-guided synchronization but not in perception (stimulus- or imagery-guided. In imagery-guided synchronization, performance accuracy decreased for beeps and balls, but not for flashes and sirens. Our findings suggest that the advantages of moving visual stimuli over static ones are grounded in action rather than perception, and they support the hypothesis that the sensorimotor coupling mechanisms for auditory (beeps and moving visual stimuli (bouncing balls overlap.

  4. Response time to colored stimuli in the full visual field

    Science.gov (United States)

    Haines, R. F.; Dawson, L. M.; Galvan, T.; Reid, L. M.

    1975-01-01

    Peripheral visual response time was measured in seven dark adapted subjects to the onset of small (45' arc diam), brief (50 msec), colored (blue, yellow, green, red) and white stimuli imaged at 72 locations within their binocular field of view. The blue, yellow, and green stimuli were matched for brightness at about 2.6 sub log 10 units above their absolute light threshold, and they appeared at an unexpected time and location. These data were obtained to provide response time and no-response data for use in various design disciplines involving instrument panel layout. The results indicated that the retina possesses relatively concentric regions within each of which mean response time can be expected to be of approximately the same duration. These regions are centered near the fovea and extend farther horizontally than vertically. Mean foveal response time was fastest for yellow and slowest for blue. Three and one-half percent of the total 56,410 trials presented resulted in no-responses. Regardless of stimulus color, the lowest percentage of no-responses occurred within 30 deg arc from the fovea and the highest within 40 deg to 80 deg arc below the fovea.

  5. Polymer-based stimuli-responsive nanosystems for biomedical applications.

    Science.gov (United States)

    Joglekar, Madhura; Trewyn, Brian G

    2013-08-01

    The application of organic polymers and inorganic/organic hybrid systems in numerous fields of biotechnology has seen a considerable growth in recent years. Typically, organic polymers with diverse structures, compositional variations and differing molecular weights have been utilized to assemble polymeric nanosystems such as polymeric micelles, polymersomes, and nanohydrogels with unique features and structural properties. The architecture of these polymeric nanosystems involves the use of both hydrophobic and hydrophilic polymeric blocks, making them suitable as vehicles for diagnostic and therapeutic applications. Recently, "smart" or "intelligent" polymers have attracted significant attention in the biomedical field wherein careful introduction of specific polymeric modalities changes a banal polymeric nanosystem to an advanced stimuli-responsive nanosystem capable of performing extraordinary functions in response to an internal or external trigger such as pH, temperature, redox, enzymes, light, magnetic, or ultrasound. Further, incorporation of inorganic nanoparticles such as gold, silica, or iron oxide with surface-bound stimuli-responsive polymers offers additional advantages and multifunctionality in the field of nanomedicine. This review covers the physical properties and applications of both organic and organic/inorganic hybrid nanosystems with specific recent breakthroughs in drug delivery, imaging, tissue engineering, and separations and provides a brief discussion on the future direction.

  6. A brain-derived metric for preferred kinetic stimuli.

    Science.gov (United States)

    Zeki, Semir; Stutters, Jonathan

    2012-02-01

    We here address the question of whether there is any correlation between subjective preference for simple configurations within a specific visual domain such as motion and strength of activity in visual areas in which that domain is emphasized. We prepared several distinctive patterns of dots in motion with various characteristics and asked humans to rate them according to their preference, before and while scanning the activity in their brains with functional magnetic resonance imaging. For simplicity, we restricted ourselves to motion in the fronto-parallel plane. Moving patterns produced activity in areas V1, V2, the V3 complex (V3, V3A, V3B) and V5, but only in areas V5, V3A/B and parietal cortex did the preferred kinetic patterns produce stronger activity when compared with the non-preferred ones. In addition, preferred patterns produced activity within field A1 of medial orbito-frontal cortex (mOFC), which is not otherwise activated by kinetic stimuli. Hence, for these areas, stronger neural activity correlated with subjective preference. We conclude that configurations of kinetic stimuli that are subjectively preferred correlate with stronger activity within early visual areas and within mOFC. This opens up the possibility of more detailed studies to relate subjective preferences to strength of activity in early visual areas and to relate activity in them to areas whose activity correlates with the subjective experience of beauty.

  7. Bimodal Stimuli Do Not Always Facilitate Infants' Rule Learning

    Directory of Open Access Journals (Sweden)

    Sin Mei Tsui

    2011-05-01

    Full Text Available Seven-month-old infants possess the ability to extract and generalize abstract rules from unimodal sequences of auditory syllables such as ABA and ABB whereas five-month-old infants are facilitated in their learning of these rules by bimodal sequences. In the current study, we investigated whether bimodal stimuli could also help infants acquire what we consider a more difficult abstract rule: AAB. Nineteen 8- to 9-month-old infants were habituated to the AAB rule with simultaneous visual shapes and speech sounds. They were later tested on their ability to discriminate this sequence from ABA and ABB with their looking times measured after each stimulus presentation at test periods. There was no significant difference in looking times amongst the different sequences, suggesting infants were not able to formulate an AAB rule different from those for ABA and ABB. Older infants' inability to utilize extra sensory information to acquire an abstract rule in which younger ones were ready to learn from unimodal stimulus (speech was unexpected. It is unclear what leads to the failure of rule learning from bimodal stimuli, but possible explanations including perceptual narrowing in the inter-sensory integration and the difference in sensory representation of abstract rules with different difficulties are discussed.

  8. Stress effects on working memory, explicit memory, and implicit memory for neutral and emotional stimuli in healthy men

    Directory of Open Access Journals (Sweden)

    Mathias Luethi

    2009-01-01

    Full Text Available Stress is a strong modulator of memory function. However, memory is not a unitary process and stress seems to exert different effects depending on the memory type under study. Here, we explored the impact of social stress on different aspects of human memory, including tests for explicit memory and working memory (for neutral materials, as well as implicit memory (perceptual priming, contextual priming and classical conditioning for emotional stimuli. A total of 35 young adult male students were randomly assigned to either the stress or the control group, with stress being induced by the Trier Social Stress Test (TSST. Salivary cortisol levels were assessed repeatedly throughout the experiment to validate stress effects. The results support previous evidence indicating complex effects of stress on different types of memory: A pronounced working memory deficit was associated with exposure to stress. No performance differences between groups of stressed and unstressed subjects were observed in verbal explicit memory (but note that learning and recall took place within 1 hour and immediately following stress or in implicit memory for neutral stimuli. Stress enhanced classical conditioning for negative but not positive stimuli. In addition, stress improved spatial explicit memory. These results reinforce the view that acute stress can be highly disruptive for working memory processing. They provide new evidence for the facilitating effects of stress on implicit memory for negative emotional materials. Our findings are discussed with respect to their potential relevance for psychiatric disorders, such as post traumatic stress disorder.

  9. Childhood Cumulative Risk Exposure and Adult Amygdala Volume and Function.

    Science.gov (United States)

    Evans, Gary W; Swain, James E; King, Anthony P; Wang, Xin; Javanbakht, Arash; Ho, S Shaun; Angstadt, Michael; Phan, K Luan; Xie, Hong; Liberzon, Israel

    2016-06-01

    Considerable work indicates that early cumulative risk exposure is aversive to human development, but very little research has examined the neurological underpinnings of these robust findings. This study investigates amygdala volume and reactivity to facial stimuli among adults (mean 23.7 years of age, n = 54) as a function of cumulative risk exposure during childhood (9 and 13 years of age). In addition, we test to determine whether expected cumulative risk elevations in amygdala volume would mediate functional reactivity of the amygdala during socioemotional processing. Risks included substandard housing quality, noise, crowding, family turmoil, child separation from family, and violence. Total and left hemisphere adult amygdala volumes were positively related to cumulative risk exposure during childhood. The links between childhood cumulative risk exposure and elevated amygdala responses to emotionally neutral facial stimuli in adulthood were mediated by the corresponding amygdala volumes. Cumulative risk exposure in later adolescence (17 years of age), however, was unrelated to subsequent adult amygdala volume or function. Physical and socioemotional risk exposures early in life appear to alter amygdala development, rendering adults more reactive to ambiguous stimuli such as neutral faces. These stress-related differences in childhood amygdala development might contribute to the well-documented psychological distress as a function of early risk exposure.

  10. A comparative analysis of the categorization of multidimensional stimuli: I. Unidimensional classification does not necessarily imply analytic processing; evidence from pigeons (Columba livia), squirrels (Sciurus carolinensis), and humans (Homo sapiens).

    Science.gov (United States)

    Wills, A J; Lea, Stephen E G; Leaver, Lisa A; Osthaus, Britta; Ryan, Catriona M E; Suret, Mark B; Bryant, Catherine M L; Chapman, Sue J A; Millar, Louise

    2009-11-01

    Pigeons (Columba livia), gray squirrels (Sciurus carolinensis), and undergraduates (Homo sapiens) learned discrimination tasks involving multiple mutually redundant dimensions. First, pigeons and undergraduates learned conditional discriminations between stimuli composed of three spatially separated dimensions, after first learning to discriminate the individual elements of the stimuli. When subsequently tested with stimuli in which one of the dimensions took an anomalous value, the majority of both species categorized test stimuli by their overall similarity to training stimuli. However some individuals of both species categorized them according to a single dimension. In a second set of experiments, squirrels, pigeons, and undergraduates learned go/no-go discriminations using multiple simultaneous presentations of stimuli composed of three spatially integrated, highly salient dimensions. The tendency to categorize test stimuli including anomalous dimension values unidimensionally was higher than in the first set of experiments and did not differ significantly between species. The authors conclude that unidimensional categorization of multidimensional stimuli is not diagnostic for analytic cognitive processing, and that any differences between human's and pigeons' behavior in such tasks are not due to special features of avian visual cognition.

  11. The Motivating Effect of Antecedent Stimuli on the Web Shop: A Conjoint Analysis of the Impact of Antecedent Stimuli at the Point of Online Purchase

    Science.gov (United States)

    Fagerstrom, Asle

    2010-01-01

    This article introduces the concept of motivating operation (MO) to the field of online consumer research. A conjoint analysis was conducted to assess the motivating impact of antecedent stimuli on online purchasing. Stimuli tested were in-stock status, price, other customers' reviews, order confirmation procedures, and donation to charity. The…

  12. The Motivating Effect of Antecedent Stimuli on the Web Shop: A Conjoint Analysis of the Impact of Antecedent Stimuli at the Point of Online Purchase

    Science.gov (United States)

    Fagerstrom, Asle

    2010-01-01

    This article introduces the concept of motivating operation (MO) to the field of online consumer research. A conjoint analysis was conducted to assess the motivating impact of antecedent stimuli on online purchasing. Stimuli tested were in-stock status, price, other customers' reviews, order confirmation procedures, and donation to charity. The…

  13. The feeling of movement: EEG evidence for mirroring activity during the observations of static, ambiguous stimuli in the Rorschach cards.

    Science.gov (United States)

    Giromini, Luciano; Porcelli, Piero; Viglione, Donald J; Parolin, Laura; Pineda, Jaime A

    2010-10-01

    The mirror neuron system (MNS) is considered the best explanation for the neural basis of embodied simulation. To date no study has investigated if it may be activated not only by actual but by the "feeling of movement". The Rorschach test cards were used to investigate evidence of EEG mu wave suppression at central areas, an index of MNS activity, since human movement responses (M) to the Rorschach elicit such feelings of movement. Nineteen healthy volunteers observed different sets of Rorschach stimuli during attribution, identification, and observation of human movements and different scenarios while their EEG were recorded. Significant mu suppression occurred when subjects perceived movement, regardless of the experimental condition. These results show that mirroring can be activated by static, ambiguous stimuli such as Rorschach cards, suggesting that internal representation of the "feeling of movement" may be sufficient to trigger MNS activity even when minimal external cues are present.

  14. Aperiodic Volume Optics

    Science.gov (United States)

    Gerke, Tim D.

    Presented in this thesis is an investigation into aperiodic volume optical devices. The three main topics of research and discussion are the aperiodic volume optical devices that we call computer-generated volume holograms (CGVH), defects within periodic 3D photonic crystals, and non-periodic, but ordered 3D quasicrystals. The first of these devices, CGVHs, are designed and investigated numerically and experimentally. We study the performance of multi-layered amplitude computer-generated volume holograms in terms of efficiency and angular/frequency selectivity. Simulation results show that such aperiodic devices can increase diffraction efficiency relative to periodic amplitude volume holograms while maintaining angular and wavelength selectivity. CGVHs are also designed as voxelated volumes using a new projection optimization algorithm. They are investigated using a volumetric diffraction simulation and a standard 3D beam propagation technique as well as experimentally. Both simulation and experiment verify that the structures function according to their design. These represent the first diffractive structures that have the capacity for generating arbitrary transmission and reflection wave fronts and that provide the ability for multiplexing arbitrary functionality given different illumination conditions. Also investigated and discussed in this thesis are 3D photonic crystals and quasicrystals. We demonstrate that these devices can be fabricated using a femtosecond laser direct writing system that is particularly appropriate for fabrication of such arbitrary 3D structures. We also show that these devices can provide 3D partial bandgaps which could become complete bandgaps if fabricated using high index materials or by coating lower index materials with high index metals. Our fabrication method is particularly suited to the fabrication of engineered defects within the periodic or quasi-periodic systems. We demonstrate the potential for fabricating defects within

  15. Renormalized Volume

    CERN Document Server

    Gover, A Rod

    2016-01-01

    For any conformally compact manifold with hypersurface boundary we define a canonical renormalized volume functional and compute an explicit, holographic formula for the corresponding anomaly. For the special case of asymptotically Einstein manifolds, our method recovers the known results. The anomaly does not depend on any particular choice of regulator, but the coefficients of divergences do. We give explicit formulae for these divergences valid for any choice of regulating hypersurface; these should be relevant to recent studies of quantum corrections to entanglement entropies. The anomaly is expressed as a conformally invariant integral of a local Q-curvature that generalizes the Branson Q-curvature by including data of the embedding. In each dimension this canonically defines a higher dimensional generalization of the Willmore energy/rigid string action. We show that the variation of these energy functionals is exactly the obstruction to solving a singular Yamabe type problem with boundary data along the...

  16. Stimuli-responsive PEGylated prodrugs for targeted doxorubicin delivery

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Minghui; Qian, Junmin, E-mail: jmqian@mail.xjtu.edu.cn; Liu, Xuefeng; Liu, Ting; Wang, Hongjie

    2015-05-01

    In recent years, stimuli-sensitive prodrugs have been extensively studied for the rapid “burst” release of antitumor drugs to enhance chemotherapeutic efficiency. In this study, a novel stimuli-sensitive prodrug containing galactosamine as a targeting moiety, poly(ethylene glycol)–doxorubicin (PEG–DOX) conjugate, was developed for targeting HepG2 human liver cancer cells. To obtain the PEG–DOX conjugate, both galactosamine-decorated poly(ethylene glycol) aldehyde (Gal-PEG-CHO) and methoxy poly(ethylene glycol) aldehyde (mPEG-CHO) were firstly synthesized and functionalized with dithiodipropionate dihydrazide (TPH) through direct reductive amination via Schiff's base formation, and then DOX molecules were chemically conjugated to the hydrazide end groups of TPH-functionalized Gal-/m-PEG chains via pH-sensitive hydrazone linkages. The chemical structures of TPH-functionalized PEG and PEG–DOX prodrug were confirmed by {sup 1}H NMR analysis. The PEG–DOX conjugate could self-assemble into spherical nanomicelles with a mean diameter of 140 nm, as indicated by transmission electron microscopy and dynamic light scattering. The drug loading content and loading efficiency in the prodrug nanomicelles were as high as 20 wt.% and 75 wt.%, respectively. In vitro drug release studies showed that DOX was released rapidly from the prodrug nanomicelles at the intracellular levels of pH and reducing agent. Cellular uptake and MTT experiments demonstrated that the galactosamine-decorated prodrug nanomicelles were more efficiently internalized into HepG2 cells via a receptor-mediated endocytosis process and exhibited a higher toxicity, compared with pristine prodrug nanomicelles. These results suggest that the novel Gal-PEG–DOX prodrug nanomicelles have tremendous potential for targeted liver cancer therapy. - Highlights: • A novel stimuli-responsive PEGylated prodrugs is synthesized. • PEGylated prodrugs can self-assemble into spherical nanoparticles (140 nm

  17. Conditioned Reinforcement and Response Strength

    Science.gov (United States)

    Shahan, Timothy A

    2010-01-01

    Stimuli associated with primary reinforcers appear themselves to acquire the capacity to strengthen behavior. This paper reviews research on the strengthening effects of conditioned reinforcers within the context of contemporary quantitative choice theories and behavioral momentum theory. Based partially on the finding that variations in parameters of conditioned reinforcement appear not to affect response strength as measured by resistance to change, long-standing assertions that conditioned reinforcers do not strengthen behavior in a reinforcement-like fashion are considered. A signposts or means-to-an-end account is explored and appears to provide a plausible alternative interpretation of the effects of stimuli associated with primary reinforcers. Related suggestions that primary reinforcers also might not have their effects via a strengthening process are explored and found to be worthy of serious consideration. PMID:20885815

  18. PREFACE: Stimuli Stimuli

    Science.gov (United States)

    Queisser, Hans J.

    2011-01-01

    Tributes are paid to Zhores Alferov by presenting personal anecdotes from the fields, where Alferov performed his pioneering research: masers, lasers, solar cells and heterojunctions. What a pleasure and honor to pay tribute to Zhores Alferov in this Festschrift. Member of a remarkable laboratory and originator of imaginative and useful ideas for semiconductor physics and technology; a happy birthday! I would like to use this opportunity to ramble a little about the physics of masers, lasers, heterojunctions, solar cells— all themes of such vital importance in Alferov's career—and also tangible in my own endeavors. I start out with an anecdote of a colloquium presentation in my youthful days at Göttingen. The Physics Colloquium at Göttingen University presented a serious weekly meeting. Werner Heisenberg and Carl Friedrich von Weizsäcker attended, often Wolfgang Pauli visited from Zurich; Otto Hahn always sat in the first row, on the left corner— and he smoked his cigar. I had just obtained my doctorate [1]— it was 1958, and my boss Rudolf Hilsch ordered me to contribute a colloquium talk. He hoped that I would report on color centers in alkali halides or review experiments on quenched amorphous bismuth, a surprising superconductor [2], or on my own dissertation [1], all recent results of our team. I, however, being an avid reader of the latest American physics literature, begged to differ. The English language gave me no problems because I had in 1951/52 spent a year at the University of Kansas. This experience in the friendly American Midwest provided me with a definite linguistic advantage over most of my German fellow students. I was fascinated by those very first reports on the maser, this molecular amplifier using ammonia for stimulated emission, and therefore decided, quite to the chagrin of my boss Hilsch, to choose this particular topic for a report at the Colloquium. So I went to the rostrum in the small auditorium 'Hörsaal II' and delivered a well-rehearsed talk. The audience was intrigued by this new principle of stimulated coherent microwave radiation [3]. Friedrich Hund, famous for his 'rule' was then our theory professor, he sat in the second row. He was very surprised, and asked me in the discussion if he had understood correctly. If it were true what I had just suggested, then the maser coherence length would go from the Earth to the Moon. I paused a little, pondered and observed my microwave-conscious friends in the audience nodding encouragingly. 'Yes, sir; I think so!' 'I don't believe it', Hund retorted. How could a youngster react? I remained silent and obediently, quite imperceptibly shrugged my shoulders. After the talk, Professor Lamla, an editor of a science journal came to congratulate me and asked for a manuscript. I delivered [4]. This item on my early publication list may have contributed to the fact that I was hired in 1959 by William Shockley to join his fledgling company Shockley Transistor in this old apricot barn on 391 South San Antonio Road in Mountain View, California [5]. I knew that it would be extremely difficult to extend the frequency into the optical regime, you have to fight against the square of the frequency. Nevertheless, I refrained from making the statement in my paper that reaching an optical maser might be hopeless [4]. 'Never say never' is an appropriate adage, not only for seniors. A young colleague, who had also written a review paper, dared to support a more pessimistic view [6]. He anticipated in his very last sentence that stimulated emission would probably prevail merely in the microwave regime. This defeatist attitude seemed to have ruled throughout Germany, as already preached in the famous textbooks by Pohl [7], and also assumed by physics Professor Hellwege at Darmstadt, who was the leading expert regarding luminescence of materials such as ruby crystals; yet Maiman and others surpassed him [8]. Silicon came next for me, working, for example, with Shockley on the theory of maximal efficiency for solar cells, not really a topic regarding coherent radiation [9]. Once, however, a discussion evolved during one of those nearly dreaded hamburger lunches with Shockley at Kirk's charcoal restaurant on El Camino Real in Mountain View. Those frugal lunches ended with a demanding one-on-one interrogation, stricter and tougher than any doctoral oral examination. 'What, you do not know of Einstein's A and B coefficients?' Next afternoon I dutifully looked them up in the Stanford physics library. My first, rather indirect contacts with semiconductor heterojunctions occurred in this former apricot barn of Shockley's. Improving junction transistors required a maximum of the emitter efficiency. The emitter-to-base junction should carry only a forward current, no particles should flow from base to emitter [10]. This requirement can be met with a heterojunction: some other semiconductor material covering the silicon. Shockley had already contemplated this possibility while still at Bell Laboratories [11]. One day, a physicist by the name of Herbert Krömer visited us. This young man had also studied at Göttingen, especially with the memorable theoretician Richard Becker, whom we all admired. Krömer had in Princeton contributed to the theoretical understanding [12] of such wide-gap emitter/base junctions, and Shockley urgently wanted to hire him. But Herb preferred to join Varian Associates, just up the road in Palo Alto. Later, it was my great pleasure to attend the Nobel Festivities for Herb and Zhores Alferov in Stockholm. In the early sixties, I became a Member of Technical Staff at the Bell Laboratories in Murray Hill, New Jersey. Now, compound semiconductors, such as gallium arsenide, had to attract my interest. By the time of the mid-sixties, helium/neon-lasers were quite the vogue; Bell Labs actually established a little workshop with a production line to fabricate them and spread them throughout the departments. 'The solution in search of a problem', as sceptics joked about this new light source, was of vital interest to us because of the high frequencies to carry plenty of information channels. Transmission of laser light straight through the air, from Building 1 to Building 2 at Murray Hill, however, showed that the atmosphere was by far too unstable. We discussed silver-plated tubes and glass fibers, which eventually became so unbelievably pure that nowadays they provide a wealth of inexpensive communication channels. A gas laser did not appear to emerge into a viable, convenient engineering solution, nor did the ruby. A diode laser source had to be developed. I used laser-induced photoluminescence to search for more efficient GaAs materials, which resulted in detecting crystals with amphoteric silicon doping of very high output in the near-infrared [13]. This invention was patented in 37 countries and provided millions of diodes, such as for TV remote control devices. I had to sign off my inventor's reward for one US dollar, which I actually did not even receive. (In earlier years, patentors obtained one silver dollar; but not anymore!) Yet my little diodes, however efficient, could not be stimulated to emit coherent light, alas! Together with my colleagues and friends Morton Panish and Craig Casey, later famous textbook authors on diode lasers [14], we searched for solutions, although colleagues at the famed RCA Laboratories in Princeton had predicted that a laser diode was impossible [15]. I remember one morning when Mort told us of a talk he had just heard at a meeting in New York City, where our friendly competitors at the IBM Labs in Yorktown Heights, NY had suggested that heterojunctions could nicely confine and concentrate carriers, maybe also photons. Such heterojunctions were then tried in Panish's lab to be grown via liquid-phase epitaxy, Stan Sumski being the expert technician. At that time, the Leningraders, under leadership of Zhores Alferov were working hard and highly successfully with this crystal growth technique. We were very much impressed by the success in Leningrad. Liquid-phase epitaxy yields, in principle, exceedingly pure crystals, but we were unhappy about the principal lack of direct monitoring during this growth process, which we deemed absolutely necessary for obtaining reproducible heterojunctions with tightly controlled small dimensions. Ultrahigh-vacuum epitaxy seemed to be the inescapable solution. Delicate molecular beams had to be gently used and monitored! What a costly proposition! I clearly remember the day when Mort and I went to the Laboratory director John Galt. A little bit fearful and subdued, we explained our project. No, not expensive, rather a very expensive idea! We anxiously watched John with his usual stern demeanour; he paused and contemplated: 'All right, we do it—go ahead!' Construction for equipment needed for the Molecular Beam Epitaxy (MBE) began, and in Al Cho, an excellent new employee was hired for this task. A little later I left Bell Labs, this fabulous 'Mecca of Solid State' for a physics professorship at the Goethe University in Frankfurt-on-the-Main in Germany. Meanwhile, successful work on semiconductor lasers bore ample fruit worldwide. In Frankfurt, I used gas laser sources for photoluminescence diagnostics of elemental and compound semiconductors. With my astute doctoral student 'Teddy' Güttler, for example, we observed impurity photoluminescence in Au-doped silicon and concluded that doping of solar cells with deep impurities would not be beneficial for cell efficiency; just the opposite would happen because of increased carrier recombination [16]. In 1968, Western Germany experienced an ultra-left-wing student rebellion. Frankfurt students violently attacked me and accused me of war research since I used lasers, obviously a deadly weapon of mass destruction. Dieter Bimberg, our co-editor of this Festschrift, will undoubtedly remember those happenings when he was a doctoral candidate. In 1968, we all assembled in Moscow for the International Conference on the Physics of Semiconductors; what a unique opportunity to meet so many Russian colleagues, including this intellectual elite from the most remarkable Joffe Institute, with Zhores Alferov a major player. In 1970, I became a founding director of the Max-Planck-Institute for Solid State Research at Stuttgart, in the Southwest of Germany. There I eventually succeeded—against massive opposition—to establish a group for MBE, which became truly successful under the very capable leadership of Klaus Ploog [17], to whom was bestowed a prize of the Seibold-Foundation for Japan-Germany Science Cooperation. Klaus von Klitzing's group in our Max-Planck-Institute in Stuttgart relies on MBE to the present day for research on the quantum Hall effect [18]. Equally, my former doctoral student Horst Stormer had to utilize excellent MBE for his Nobel-Prize winning research on the fractional quantum Hall effect [18]. We fondly remember one congenial dinner party at our Stuttgart house, with Zhores Alferov and Helmut Lotsch as our valued guests; it must have been in the mid-seventies. My wife Inge had prepared a dessert in the shape of the title page of the Springer journal Applied Physics, with chocolate and orange cream. Herr Lotsch had won Alferov to become part of our board of editors, a most valuable connection to the excellence of Soviet semiconductor research! Many Japanese colleagues, especially from industrial electronics labs came to learn the tricks of MBE from us in Stuttgart; the German electronics industry, however, was reluctant and remained completely disinterested—but the French equipment maker RIBER was our staunch ally, and this company grew with the international acceptance of MBE for small, high-frequency devices. One diligent young visitor at my Stuttgart laboratories, Ozamu Kumagai from the SONY Corporation, did especially well. Back at home, he most cleverly devised novel technologies for efficient and low-cost production of laser diodes and thus earned a promotion to Vice Presidency. One of the most recent, gratifying encounters with Zhores Alferov happened to me in a cozy retreat in the forests near Madrid, with Antonio Luque being our gracious host for a solar cell symposium. We Stuttgarters had hoped to use multi-pair generation in perfected silicon solar cells [19], but a better chance to capture more photons from the solar spectrum exists most likely in multi-junction cells [20], with fancy tunnel-contacts interconnecting between heterojunctions. We shall see if this approach might eventually lead to more efficient, yet still economical solar energy conversion. Semiconductor heterojunctions for communications and consumers! Many of Alferov's present activities in St Petersburg and Berlin are governed by this magic modern prefix nano, which might one day also provide some applications in solar cells; but we have yet to carefully investigate [21]! References [1] Queisser H J 1958 Z.Physik 152 507 and 495 [2] Buckel W and Hilsch R 1956 Z. Physik 146 27 [3] Wittke J P 1957 Proc. IRE 45 291 with references to earlier work [4] Queisser H J 1959 Naturwiss. 46 394 [5] Queisser H J 1988 The Conquest of the Microchip (Cambridge, MA: Harvard University Press) [6] Wolf H C and Agnew Z 1958 Physik 10 480 [7] Pohl R W Optik (Heidelberg: Springer) [8] Yariv A 1968 Quantum Electronics (New York: Wiley) [9] Shockley W and Queisser H J 1961 J. Appl. Phys. 32 510 [10] For details, see Sze S M and Ng K K 2007 Physics of Semiconductor Devices 3rd edn (Hoboken, NJ: Wiley) [11] Shockley W 1951 US Patent Specification 2.569.347 [12] Krömer H 1957 Proc. IRE 45 1535 [13] Queisser H J 1966 J. Appl. Phys. 37 2909 (this paper was withheld internally for some time due to the patent application: US Pat.3.387.163) [14] Panish M B and Casey C H 1978 Heterostructure Lasers (New York: Academic) [15] Kressel H Private communications [16] Güttler G and Queisser H J 1996 J. Appl. Phys. 40 4994 [17] Ploog K and Graf K 1984 MBE of III-V Compounds (Berlin: Springer) [18] For recent coverage, see Chakraborty T and Pietiläinen P 1995 The Quantum Hall Effect (Berlin: Springer) [19] Werner J H, Kolodinski S and Queisser H J 1993 Phys. Rev. Lett. 72 3851 [20] Yamaguchi M 2002 Physica E 14 84 [21] Queisser H J 2002 Physica E 14 1 and many other contributions in this issue

  19. Diurnal cortisol amplitude and fronto-limbic activity in response to stressful stimuli.

    Science.gov (United States)

    Cunningham-Bussel, Amy C; Root, James C; Butler, Tracy; Tuescher, Oliver; Pan, Hong; Epstein, Jane; Weisholtz, Daniel S; Pavony, Michelle; Silverman, Michael E; Goldstein, Martin S; Altemus, Margaret; Cloitre, Marylene; Ledoux, Joseph; McEwen, Bruce; Stern, Emily; Silbersweig, David

    2009-06-01

    The development and exacerbation of many psychiatric and neurologic conditions are associated with dysregulation of the hypothalamic pituitary adrenal (HPA) axis as measured by aberrant levels of cortisol secretion. Here we report on the relationship between the amplitude of diurnal cortisol secretion, measured across 3 typical days in 18 healthy individuals, and blood oxygen level dependant (BOLD) response in limbic fear/stress circuits, elicited by in-scanner presentation of emotionally negative stimuli, specifically, images of the World Trade Center (WTC) attack. Results indicate that subjects who secrete a greater amplitude of cortisol diurnally demonstrate less brain activation in limbic regions, including the amygdala and hippocampus/parahippocampus, and hypothalamus during exposure to traumatic WTC-related images. Such initial findings can begin to link our understanding, in humans, of the relationship between the diurnal amplitude of a hormone integral to the stress response, and those neuroanatomical regions that are implicated as both modulating and being modulated by that response.

  20. A review of stimuli-responsive polymers for smart textile applications

    Science.gov (United States)

    Hu, Jinlian; Meng, Harper; Li, Guoqiang; Ibekwe, Samuel I.

    2012-05-01

    Stimuli-responsive polymers (SRPs) are smart materials which can show noticeable changes in their properties with environmental stimulus variations. Novel functionalities can be delivered to textiles by integrating smart SRPs into them. SRPs inclusive of thermal-responsive polymers, moisture-responsive polymers, thermal-responsive hydrogels, pH-responsive hydrogels, and light-responsive polymers have been applied in textiles to improve or achieve textile smart functionalities. The functionalities include aesthetic appeal, comfort, textile soft display, smart controlled drug release, fantasy design with color changing, wound monitoring, smart wetting properties and protection against extreme variations in environmental conditions. In this review, the applications of SRPs in the textile and clothing sector are elucidated; the associated constraints in fabrication processes for textiles and their potential applications in the near future are discussed.

  1. Dual Stimuli-Responsive Poly(β-amino ester) Nanoparticles for On-Demand Burst Release.

    Science.gov (United States)

    Lee, Jung Seok; Deng, Xiaojian; Han, Patrick; Cheng, Jianjun

    2015-09-01

    We designed poly(β-amino esters) (PBAEs) bearing both UV light- and pH-sensitive groups and used PBAEs to prepare nanoparticles (NPs) that can be utilized for on-demand burst release of guest molecules in response to multiple triggers. Due to the presence of the photo-cleavable group in each repeating unit of PBAE, rapid release of encapsulated model drug could be achieved even with exposures to low intensity UV (10 mW · cm(-2) ). Especially, the burst release was further accelerated by additional UV treatments in the acidic condition showing the combinatory effect of dual stimuli. We believe these PBAE-based NPs can potentially be used to design intelligent controlled release device and nanomedicines.

  2. Stimuli-responsive cylindrical hydrogels mimic intestinal peristalsis to propel a solid object.

    Science.gov (United States)

    Nistor, V; Cannell, J; Gregory, J; Yeghiazarian, L

    2016-04-21

    The emerging field of soft robotics relies on soft, stimuli-responsive materials to enable load transport, manipulation, and mobility in complex unconstrained environments. These materials often need to replicate biological functionality such as muscle contractions and flexibility. Here we demonstrate a soft actuator prototype based on thermosensitive PNIPAAM hydrogels that can transport and manipulate objects. A hollow cylindrical hydrogel was selectively heated and cooled with Peltier devices to yield a traveling wave of shrinking and swelling akin to intestinal peristalsis. A 4 mm diameter bead was placed inside the cylinder and propelled 19.5 mm, equal to distance traveled by the peristaltic wave. We derived conditions that enable peristaltic transport as a function of transporter-cargo design parameters. We conclude that hydrogel-based peristaltic manipulators covering 2 orders of magnitude in stiffness (1-10(2) kPa) could transport cargo spanning 4 orders of magnitude in size (μm-m).

  3. Direct activation of the ventral striatum in anticipation of aversive stimuli.

    Science.gov (United States)

    Jensen, Jimmy; McIntosh, Anthony R; Crawley, Adrian P; Mikulis, David J; Remington, Gary; Kapur, Shitij

    2003-12-18

    The brain "reward" system, centered on the limbic ventral striatum, plays a critical role in the response to pleasure and pain. The ventral striatum is activated in animal and human studies during anticipation of appetitive/pleasurable events, but its role in aversive/painful events is less clear. Here we present data from three human fMRI studies based on aversive conditioning using unpleasant cutaneous electrical stimulation and show that the ventral striatum is reliably activated. This activation is observed during anticipation and is not a consequence of relief after the aversive event. Further, the ventral striatum is activated in anticipation regardless of whether there is an opportunity to avoid the aversive stimulus or not. Our data suggest that the ventral striatum, a crucial element of the brain "reward" system, is directly activated in anticipation of aversive stimuli.

  4. Strength stimuli on the quadriceps femoris influences the physiological tremor of the index finger

    CERN Document Server

    Lainez, Miguel J A; Gallach, Jose E; Moras, Gerard; Ranz, Daniel; Toca-Herrera, Jose L

    2008-01-01

    The influence of fatiguing stimuli applied to the quadriceps femoris on the tremor of the index finger on sixteen healthy subjects has been investigated, by measuring the acceleration and the electromyography activity of the extensor digitorum at two different speeds. No significant changes in the basal condition could be measured at 0.52 rad/s. However, at 1.05 rad/s the tremor amplitude (12.23%, p<0.05) and the electromyography activity (20.19%, p<0.05) increased in the time domain. In the frequential domain, the peak associated to the acceleration increased in 26.30% (p<0.05), while the electromiography activity experienced an increase of 81.34% (p<0.05). The largest change in frequency took place in the range 7-17 Hz. The discussion of the results leads to the conclusion that the supraespinal mechanism is responsible for the measured effect.

  5. Use of Acoustics in Studies of Fish Reaction to Imposed Stimuli

    Directory of Open Access Journals (Sweden)

    E. Ona

    1986-10-01

    Full Text Available The general distribution pattern of fish in a large pen is described through essentially simultaneous measurements of the integrated echo intensity in each of six separate cells using transducers mounted below the pen. The reaction of fish to various stimuli imposed in one of the cells is quantified by the change in frequency distribution of the echo intensity relative to the undisturbed situation. The experiment was part of a small-scale test of equipment to be used for observations of the attraction-effect of fish to oil-rig structures. The method seems to be suitable both for general fish behaviour studies, including attraction and avoidance effect, and for monitoring feeding systems in aquaculture based on fish conditioning.

  6. Electrical conditioning of adipose-derived stem cells in a multi-chamber culture platform.

    Science.gov (United States)

    Pavesi, A; Soncini, M; Zamperone, A; Pietronave, S; Medico, E; Redaelli, A; Prat, M; Fiore, G B

    2014-07-01

    In tissue engineering, several factors play key roles in providing adequate stimuli for cells differentiation, in particular biochemical and physical stimuli, which try to mimic the physiological microenvironments. Since electrical stimuli are important in the developing heart, we have developed an easy-to-use, cost-effective cell culture platform, able to provide controlled electrical stimulation aimed at investigating the influence of the electric field in the stem cell differentiation process. This bioreactor consists of an electrical stimulator and 12 independent, petri-like culture chambers and a 3-D computational model was used to characterize the distribution and the intensity of the electric field generated in the cell culture volume. We explored the effects of monophasic and biphasic square wave pulse stimulation on a mouse adipose-derived stem cell line (m17.ASC) comparing cell viability, proliferation, protein, and gene expression. Both monophasic (8 V, 2 ms, 1 Hz) and biphasic (+4 V, 1 ms and -4 V, 1 ms; 1 Hz) stimulation were compatible with cell survival and proliferation. Biphasic stimulation induced the expression of Connexin 43, which was found to localize also at the cell membrane, which is its recognized functional mediating intercellular electrical coupling. Electrically stimulated cells showed an induced transcriptional profile more closely related to that of neonatal cadiomyocytes, particularly for biphasic stimulation. The developed platform thus allowed to set-up precise conditions to drive adult stem cells toward a myocardial phenotype solely by physical stimuli, in the absence of exogenously added expensive bioactive molecules, and can thus represent a valuable tool for translational applications for heart tissue engineering and regeneration.

  7. Classical Conditioning: Eliciting the Right Response.

    Science.gov (United States)

    Tauber, Robert T.

    1990-01-01

    Classical conditioning is responsible for students' positive and negative feelings, whether directed toward subject matter, peers, teachers, or education in general. This article explains how educators can use classical conditioning principles (such as reinforcement, extinction, and paired stimuli) to create an anxiety-free learning environment.…

  8. The relativity of time perception produced by facial emotion stimuli.

    Science.gov (United States)

    Lee, Kwang-Hyuk; Seelam, Kalyan; O'Brien, Tom

    2011-12-01

    We systematically examined the impact of emotional stimuli on time perception in a temporal reproduction paradigm where participants reproduced the duration of a facial emotion stimulus using an oval-shape stimulus or vice versa. Experiment 1 asked participants to reproduce the duration of an angry face (or the oval) presented for 2,000 ms. Experiment 2 included a range of emotional expressions (happy, sad, angry, and neutral faces as well as the oval stimulus) presented for different durations (500, 1,500, and 2,000 ms). We found that participants over-reproduced the durations of happy and sad faces using the oval stimulus. By contrast, there was a trend of under-reproduction when the duration of the oval stimulus was reproduced using the angry face. We suggest that increased attention to a facial emotion produces the relativity of time perception.

  9. Stimuli-Directed Helical Chirality Inversion and Bio-Applications

    Directory of Open Access Journals (Sweden)

    Ziyu Lv

    2016-08-01

    Full Text Available Helical structure is a sophisticated ubiquitous motif found in nature, in artificial polymers, and in supramolecular assemblies from microscopic to macroscopic points of view. Significant progress has been made in the synthesis and structural elucidation of helical polymers, nevertheless, a new direction for helical polymeric materials, is how to design smart systems with controllable helical chirality, and further use them to develop chiral functional materials and promote their applications in biology, biochemistry, medicine, and nanotechnology fields. This review summarizes the recent progress in the development of high-performance systems with tunable helical chirality on receiving external stimuli and discusses advances in their applications as drug delivery vesicles, sensors, molecular switches, and liquid crystals. Challenges and opportunities in this emerging area are also presented in the conclusion.

  10. Balancing Attended and Global Stimuli in Perceived Video Quality Assessment

    DEFF Research Database (Denmark)

    You, Junyong; Korhonen, Jari; Perkis, Andrew

    2011-01-01

    The visual attention mechanism plays a key role in the human perception system and it has a significant impact on our assessment of perceived video quality. In spite of receiving less attention from the viewers, unattended stimuli can still contribute to the understanding of the visual content....... This paper proposes a quality model based on the late attention selection theory, assuming that the video quality is perceived via two mechanisms: global and local quality assessment. First we model several visual features influencing the visual attention in quality assessment scenarios to derive...... an attention map using appropriate fusion techniques. The global quality assessment as based on the assumption that viewers allocate their attention equally to the entire visual scene, is modeled by four carefully designed quality features. By employing these same quality features, the local quality model...

  11. Executive control suppresses pupillary responses to aversive stimuli.

    Science.gov (United States)

    Cohen, Noga; Moyal, Natali; Henik, Avishai

    2015-12-01

    Adaptive behavior depends on the ability to effectively regulate emotional responses. Continuous failure in the regulation of emotions can lead to heightened physiological reactions and to various psychopathologies. Recently, several behavioral and neuroimaging studies showed that exertion of executive control modulates emotion. Executive control is a high-order operation involved in goal-directed behavior, especially in the face of distractors or temptations. However, the role of executive control in regulating emotion-related physiological reactions is unknown. Here we show that exercise of executive control modulates reactivity of both the sympathetic and the parasympathetic components of the autonomic nervous system. Specifically, we demonstrate that both pupillary light reflex and pupil dilation for aversive stimuli are attenuated following recruitment of executive control. These findings offer new insights into the very basic mechanisms of emotion processing and regulation, and can lead to novel interventions for people suffering from emotion dysregulation psychopathologies. Copyright © 2015 Elsevier B.V. All rights reserved.

  12. Stimuli Responsive Ionogels for Sensing Applications—An Overview

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    Andrew Kavanagh

    2012-02-01

    Full Text Available This overview aims to summarize the existing potential of “Ionogels” as a platform to develop stimuli responsive materials. Ionogels are a class of materials that contain an Ionic Liquid (IL confined within a polymer matrix. Recently defined as “a solid interconnected network spreading throughout a liquid phase”, the ionogel therefore combines the properties of both its solid and liquid components. ILs are low melting salts that exist as liquids composed entirely of cations and anions at or around 100 °C. Important physical properties of these liquids such as viscosity, density, melting point and conductivity can be altered to suit a purpose by choice of the cation/anion. Here we provide an overview to highlight the literature thus far, detailing the encapsulation of IL and responsive materials within these polymeric structures. Exciting applications in the areas of optical and electrochemical sensing, solid state electrolytes and actuating materials shall be discussed.

  13. Dinoflagellate bioluminescence in response to mechanical stimuli in water flows

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    A. S. Cussatlegras

    2005-01-01

    Full Text Available Bioluminescence of plankton organisms induced by water movements has long been observed and is still under investigations because of its great complexity. In particular, the exact mechanism occurring at the level of the cell has not been yet fully understood. This work is devoted to the study of the bioluminescence of the dinoflagellates plankton species Pyrocystis noctiluca in response to mechanical stimuli generated by water flows. Several experiments were performed with different types of flows in a Couette shearing apparatus. All of them converge to the conclusion that stationary homogeneous laminar shear does not trigger massive bioluminescence, but that acceleration and shear are both necessary to stimulate together an intense bioluminescence response. The distribution of the experimental bioluminescence thresholds is finally calculated from the light emission response for the Pyrocystis noctiluca species.

  14. Stimuli-sensitive hydrogels for pharmaceutical and medical applications

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    Ilić-Stojanović Snežana

    2011-01-01

    Full Text Available Hydrogels are three-dimensional cross-linked hydrophilic polymers that swell in water and aqueous solutions without dissolving in them. They are very sensitive to environmental stimulus, which is manifested by a sharp phase transition. This feature is important for their application in the pharmaceutical field, especially for making formulations with controlled release of active ingredients, with the correction of the solubility, degradation and their toxicity reducing. Because of the compatibility with living tissues, hydrogels can be used in different medical purposes (for making contact lenses, stents, balloon catheters, artificial muscles, substitutes for arteries and veins, trachea, oviduct. This work presents methods (chemical and physical for obtaining hydrogels, their properties and sensitivity to environmental stimuli (temperature, pH, magnetic field, as well as their potential application in medicine and pharmacy.

  15. What boxing-related stimuli reveal about response behaviour.

    Science.gov (United States)

    Ottoboni, Giovanni; Russo, Gabriele; Tessari, Alessia

    2015-01-01

    When two athletes meet inside the ropes of the boxing ring to fight, their cognitive systems have to respond as quickly as possible to a manifold of stimuli to assure victory. In the present work, we studied the pre-attentive mechanisms, which form the basis of an athlete's ability in reacting to an opponent's punches. Expert boxers, beginner boxers and people with no experience of boxing performed a Simon-like task where they judged the colour of the boxing gloves worn by athletes in attack postures by pressing two lateralised keys. Although participants were not instructed to pay attention to the direction of the punches, beginner boxers' responses resembled a defence-related pattern, expert boxers' resembled counterattacks, whereas non-athletes' responses were not influenced by the unrelated task information. Results are discussed in the light of an expertise-related action simulation account.

  16. Enhanced discriminative fear learning of phobia-irrelevant stimuli in spider-fearful individuals

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    Carina eMosig

    2014-10-01

    Full Text Available Avoidance is considered as a central hallmark of all anxiety disorders. The acquisition and expression of avoidance which leads to the maintenance and exacerbation of pathological fear is closely linked to Pavlovian and operant conditioning processes. Changes in conditionability might represent a key feature of all anxiety disorders but the exact nature of these alterations might vary across different disorders. To date, no information is available on specific changes in conditionability for disorder-irrelevant stimuli in specific phobia (SP. The first aim of this study was to investigate changes in fear acquisition and extinction in spider-fearful individuals as compared to non-fearful participants by using the de novo fear conditioning paradigm. Secondly, we aimed to determine whether differences in the magnitude of context-dependent fear retrieval exist between spider-fearful and non-fearful individuals. Our findings point to an enhanced fear discrimination in spider-fearful individuals as compared to non-fearful individuals at both the physiological and subjective level. The enhanced fear discrimination in spider-fearful individuals was neither mediated by increased state anxiety, depression, nor stress tension. Spider-fearful individuals displayed no changes in extinction learning and/or fear retrieval. Surprisingly, we found no evidence for context-dependent modulation of fear retrieval in either group. Here we provide first evidence that spider-fearful individuals show an enhanced discriminative fear learning of phobia-irrelevant (de novo stimuli. Our findings provide novel insights into the role of fear acquisition and expression for the development and maintenance of maladaptive responses in the course of SP.

  17. A solution for measuring accurate reaction time to visual stimuli realized with a programmable microcontroller.

    Science.gov (United States)

    Ohyanagi, Toshio; Sengoku, Yasuhito

    2010-02-01

    This article presents a new solution for measuring accurate reaction time (SMART) to visual stimuli. The SMART is a USB device realized with a Cypress Programmable System-on-Chip (PSoC) mixed-signal array programmable microcontroller. A brief overview of the hardware and firmware of the PSoC is provided, together with the results of three experiments. In Experiment 1, we investigated the timing accuracy of the SMART in measuring reaction time (RT) under different conditions of operating systems (OSs; Windows XP or Vista) and monitor displays (a CRT or an LCD). The results indicated that the timing error in measuring RT by the SMART was less than 2 msec, on average, under all combinations of OS and display and that the SMART was tolerant to jitter and noise. In Experiment 2, we tested the SMART with 8 participants. The results indicated that there was no significant difference among RTs obtained with the SMART under the different conditions of OS and display. In Experiment 3, we used Microsoft (MS) PowerPoint to present visual stimuli on the display. We found no significant difference in RTs obtained using MS DirectX technology versus using the PowerPoint file with the SMART. We are certain that the SMART is a simple and practical solution for measuring RTs accurately. Although there are some restrictions in using the SMART with RT paradigms, the SMART is capable of providing both researchers and health professionals working in clinical settings with new ways of using RT paradigms in their work.

  18. Perfusion-related stimuli for compensatory lung growth following pneumonectomy.

    Science.gov (United States)

    Dane, D Merrill; Yilmaz, Cuneyt; Gyawali, Dipendra; Iyer, Roshni; Ravikumar, Priya; Estrera, Aaron S; Hsia, Connie C W

    2016-07-01

    Following pneumonectomy (PNX), two separate mechanical forces act on the remaining lung: parenchymal stress caused by lung expansion, and microvascular distension and shear caused by increased perfusion. We previously showed that parenchymal stress and strain explain approximately one-half of overall compensation; the remainder was presumptively attributed to perfusion-related factors. In this study, we directly tested the hypothesis that perturbation of regional pulmonary perfusion modulates post-PNX lung growth. Adult canines underwent banding of the pulmonary artery (PAB) to the left caudal (LCa) lobe, which caused a reduction in basal perfusion to LCa lobe without preventing the subsequent increase in its perfusion following right PNX while simultaneously exaggerating the post-PNX increase in perfusion to the unbanded lobes, thereby creating differential perfusion changes between banded and unbanded lobes. Control animals underwent sham pulmonary artery banding followed by right PNX. Pulmonary function, regional pulmonary perfusion, and high-resolution computed tomography of the chest were analyzed pre-PNX and 3-mo post-PNX. Terminally, the remaining lobes were fixed for detailed morphometric analysis. Results were compared with corresponding lobes in two control (Sham banding and normal unoperated) groups. PAB impaired the indices of post-PNX extravascular alveolar tissue growth by up to 50% in all remaining lobes. PAB enhanced the expected post-PNX increase in alveolar capillary formation, measured by the prevalence of double-capillary profiles, in both unbanded and banded lobes. We conclude that perfusion distribution provides major stimuli for post-PNX compensatory lung growth independent of the stimuli provided by lung expansion and parenchymal stress and strain.

  19. Alexithymia and automatic processing of emotional stimuli: a systematic review.

    Science.gov (United States)

    Donges, Uta-Susan; Suslow, Thomas

    2017-04-01

    Alexithymia is a personality trait characterized by difficulties in recognizing and verbalizing emotions and the utilization of a cognitive style that is oriented toward external events, rather than intrapsychic experiences. Alexithymia is considered a vulnerability factor influencing onset and course of many psychiatric disorders. Even though emotions are, in general, elicited involuntarily and emerge without conscious effort, it is surprising that little attention in etiological considerations concerning alexithymia has been given to deficits in automatic emotion processing and their neurobiological bases. In this article, results from studies using behavioral or neurobiological research methods were systematically reviewed in which automatic processing of external emotional information was investigated as a function of alexithymia in healthy individuals. Twenty-two studies were identified through a literature search of Psycinfo, PubMed, and Web of Science databases from 1990 to 2016. The review reveals deficits in the automatic processing of emotional stimuli in alexithymia at a behavioral and neurobiological level. The vast majority of the reviewed studies examined visual processing. The alexithymia facets externally oriented thinking and difficulties identifying feelings were found to be related to impairments in the automatic processing of threat-related facial expressions. Alexithymic individuals manifest low reactivity to barely visible negative emotional stimuli in brain regions responsible for appraisal, encoding, and affective response, e.g. amygdala, occipitotemporal areas, and insula. Against this background, it appears plausible to assume that deficits in automatic emotion processing could be factors contributing to alexithymic personality characteristics. Directions for future research on alexithymia and automatic emotion perception are suggested.

  20. Analyzing the User Behavior toward Electronic Commerce Stimuli

    Science.gov (United States)

    Lorenzo-Romero, Carlota; Alarcón-del-Amo, María-del-Carmen; Gómez-Borja, Miguel-Ángel

    2016-01-01

    Based on the Stimulus-Organism-Response paradigm this research analyzes the main differences between the effects of two types of web technologies: Verbal web technology (i.e., navigational structure as utilitarian stimulus) versus non-verbal web technology (music and presentation of products as hedonic stimuli). Specific webmosphere stimuli have not been examined yet as separate variables and their impact on internal and behavioral responses seems unknown. Therefore, the objective of this research consists in analyzing the impact of these web technologies –which constitute the web atmosphere or webmosphere of a website– on shopping human behavior (i.e., users’ internal states -affective, cognitive, and satisfaction- and behavioral responses – approach responses, and real shopping outcomes-) within the retail online store created by computer, taking into account some mediator variables (i.e., involvement, atmospheric responsiveness, and perceived risk). A 2 (“free” versus “hierarchical” navigational structure) × 2 (“on” versus “off” music) × 2 (“moving” versus “static” images) between-subjects computer experimental design is used to test empirically this research. In addition, an integrated methodology was developed allowing the simulation, tracking and recording of virtual user behavior within an online shopping environment. As main conclusion, this study suggests that the positive responses of online consumers might increase when they are allowed to freely navigate the online stores and their experience is enriched by animate gifts and music background. The effect caused by mediator variables modifies relatively the final shopping human behavior. PMID:27965549

  1. Dopamine, paranormal belief, and the detection of meaningful stimuli.

    Science.gov (United States)

    Krummenacher, Peter; Mohr, Christine; Haker, Helene; Brugger, Peter

    2010-08-01

    Dopamine (DA) is suggested to improve perceptual and cognitive decisions by increasing the signal-to-noise ratio. Somewhat paradoxically, a hyperdopaminergia (arguably more accentuated in the right hemisphere) has also been implied in the genesis of unusual experiences such as hallucinations and paranormal thought. To test these opposing assumptions, we used two lateralized decision tasks, one with lexical (tapping left-hemisphere functions), the other with facial stimuli (tapping right-hemisphere functions). Participants were 40 healthy right-handed men, of whom 20 reported unusual, "paranormal" experiences and beliefs ("believers"), whereas the remaining participants were unexperienced and critical ("skeptics"). In a between-subject design, levodopa (200 mg) or placebo administration was balanced between belief groups (double-blind procedure). For each task and visual field, we calculated sensitivity (d') and response tendency (criterion) derived from signal detection theory. Results showed the typical right visual field advantage for the lexical decision task and a higher d' for verbal than facial stimuli. For the skeptics, d' was lower in the levodopa than in the placebo group. Criterion analyses revealed that believers favored false alarms over misses, whereas skeptics displayed the opposite preference. Unexpectedly, under levodopa, these decision preferences were lower in both groups. We thus infer that levodopa (1) decreases sensitivity in perceptual-cognitive decisions, but only in skeptics, and (2) makes skeptics less and believers slightly more conservative. These results stand at odd to the common view that DA generally improves signal-to-noise ratios. Paranormal ideation seems an important personality dimension and should be assessed in investigations on the detection of signals in noise.

  2. The influence of various distracting stimuli on spatial working memory

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    Martina Starc

    2016-01-01

    Full Text Available Protecting information from distraction is essential for optimal performance of working memory. We examined how the presence of distracting stimuli influences spatial working memory and compared the effect of both task-similar and negatively emotionally salient distractors. We checked the effect of distractors on the accuracy of high-resolution representations, as well as the maintenance of spatial categories, and more precisely defined not only the existence but also the direction of the distracting influences (towards or away from the position of the distractor. Participants (n = 25, 8 men, 19–31 years old were asked to remember the exact position of a target scrambled image and recall it with a joystick after a delay. In some trials an additional distracting image (scrambled, neutral or negative was shown during the delay. We measured the spread of responses (standard deviation of angular error and shifts of the average response towards the prototype angles (45° or towards the position of distractors. Distracting stimuli did not affect the spread of responses and decreased the tendency of participants to move the responses towards the prototype angle. Different types of distractors did not differ in this effect. Contrary to expectations, the participants moved their responses away from the position of distractors; this effect was more pronounced for negative distractors. In addition to memorizing the exact position and maintaining attention on the position of the stimulus, participants are likely to strategically use information about spatial category membership (quadrants and information about the position of the distractor. The repulsive effect of the distractor likely results from inhibition of its position and indicates the need to supplement computational models of spatial working memory and to take into account different strategies of working memory use.

  3. Stimuli-sensitive hydrogels: A novel ophthalmic drug delivery system

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    Singh Vinod

    2010-01-01

    Full Text Available Background: Stimuli-sensitive hydrogels are three-dimensional, hydrophilic, polymeric networks capable of imbibing large amounts of water or biological fluids on stimulation, such as pH, temperature and ionic change. Aim: To develop hydrogels that are sensitive to stimuli, i.e. pH, in the cul-de-sac of the eye for providing a prolonged effect and increased bioavailability with reduction in frequency of administration. Materials and Methods: Hydrogels were formulated by using timolol maleate as the model drug, polyacrylic acid as the gelling agents, hydroxyl ethyl cellulose as the viscolizer and sodium chloride as the isotonic agent. Stirring of ingredients in pH 4 phosphate buffer at high speed was carried out. The dynamic dialysis technique was used for drug release studies. In vivo study for reduction in intraocular pressure was carried out by using albino rabbits. Statistical Analysis: Drug release studies data were used for statistical analysis in first-order plots, Higuchi plots and Peppas exponential plots. Student t-test was performed for in vivo study. Results: Viscosity of the hydrogel increases from 3.84 cps to 9.54 cps due to change in pH 4 to pH 7.4. The slope value of the Peppas equation was found to be 0.3081, 0.3743 and 0.2964. Up to 80% of drug was released in an 8 h drug release study. Sterile hydrogels with no ocular irritation were obtained. Conclusions: Hydrogels show increase in viscosity due to change in pH. Hydrogels were therapeutically effacious, stable, non-irritant and showed Fickian diffusion. In vivo results clearly show a prolonged reduction in intraocular pressure, which was helpful for reduction in the frequency of administration.

  4. The effects of association strength and cross-modal correspondence on the development of multimodal stimuli.

    Science.gov (United States)

    Chan, Zara P Y; Dyson, Benjamin J

    2015-02-01

    In addition to temporal and spatial contributions, multimodal binding is also influenced by association strength and the congruency between stimulus elements. A paradigm was established in which an audio-visual stimulus consisting of four attributes (two visual, two auditory) was presented, followed by questions regarding the specific nature of two of those attributes. We wanted to know how association strength and congruency would modulate the basic effect that responding to same-modality information (two visual or two auditory) would be easier than retrieving different-modality information (one visual and one auditory). In Experiment 1, association strengths were compared across three conditions: baseline, intramodal (100 % association within modalities, thereby benefiting same-modality retrieval), and intermodal (100 % association between modalities, thereby benefiting different-modality retrieval). Association strength was shown to damage responses to same-modality information during intermodal conditions. In Experiment 2, association strength was manipulated identically, but was combined with cross-modally corresponding stimuli (further benefiting different-modality retrieval). The locus of the effect was again on responses to same-modality information, damaging responding during intermodal conditions but helping responding during intramodal conditions. The potential contributions of association strength and cross-modal congruency in promoting learning between vision and audition are discussed in relation to a potential default within-modality binding mechanism.

  5. Sexual behavior and responsiveness to sexual stimuli following laboratory-induced sexual arousal.

    Science.gov (United States)

    Both, Stephanie; Spiering, Mark; Everaerd, Walter; Laan, Ellen

    2004-08-01

    Sexual excitement can be seen as an action disposition. In this study sexual arousal was expected to generate sexual action and to increase interest and responsiveness to sexual stimuli. In two experiments, male and female participants were exposed to a neutral or a sexual film. We measured genital and subjective responses to the film, and sexual behavior following the laboratory visit. In Experiment 2, film exposure was followed by a task in which participants rated the sexual arousability of neutral and sexual pictures. Rating time of the sexual pictures served as an index for sexual interest. Responsiveness to the sexual pictures was measured by modulation of spinal tendinous (T) reflexes. Sexual activity, but not sexual desire, was higher for participants in the sexual film condition than for participants in the neutral condition. Sexual interest and responsiveness to still pictures were not higher for participants in the sexual film condition than for those in the neutral film condition. In addition, men who saw the neutral film showed a greater responsiveness to still pictures than men who saw the sexual film. The results support the view of sexual arousal as an emotional state generating action tendencies and actual sexual behavior.

  6. Comparison of EEG propagation speeds under emotional stimuli on smartphone between the different anxiety states

    Directory of Open Access Journals (Sweden)

    Tetsuya eAsakawa

    2014-12-01

    Full Text Available The current study was evaluated difference anxiety states at information processing in the electroencephalography (EEG under emotional stimuli for smartphone. Twenty-three healthy subjects were assessed for their anxiety states using The State Trait Anxiety Inventory (STAI and divided to two groups: low anxiety (I, II or high anxiety (III and IV, V group. EEG was measured under emotionally audio-visual stimuli (resting and pleasant, unpleasant sessions and emotionally sentence stimuli (pleasant sentence, unpleasant sentence sessions using emotionally audio-visual stimuli and emotionally sentence stimuli and analyzed using propagation speed analysis. The propagation speed of the low anxiety group at medial coronal in resting stimuli for all time was higher than those of high anxiety group, and that of the low anxiety group at medial sagittal in unpleasant stimuli for 60-150 seconds and those in unpleasant stimuli for 0-30, 60-150 seconds was higher than those of high anxiety group. The propagation speed for 150 seconds of all stimuli in the low anxiety group had a significantly higher than propagation speed for that in the high anxiety group. These events suggest that information processes concerning the emotional stimuli in the brain is differ based on the anxiety state of the subject.

  7. Multi-Stimuli-Responsive Polymer Materials: Particles, Films, and Bulk Gels.

    Science.gov (United States)

    Cao, Zi-Quan; Wang, Guo-Jie

    2016-06-01

    Stimuli-responsive polymers have received tremendous attention from scientists and engineers for several decades due to the wide applications of these smart materials in biotechnology and nanotechnology. Driven by the complex functions of living systems, multi-stimuli-responsive polymer materials have been designed and developed in recent years. Compared with conventional single- or dual-stimuli-based polymer materials, multi-stimuli-responsive polymer materials would be more intriguing since more functions and finer modulations can be achieved through more parameters. This critical review highlights the recent advances in this area and focuses on three types of multi-stimuli-responsive polymer materials, namely, multi-stimuli-responsive particles (micelles, micro/nanogels, vesicles, and hybrid particles), multi-stimuli-responsive films (polymer brushes, layer-by-layer polymer films, and porous membranes), and multi-stimuli-responsive bulk gels (hydrogels, organogels, and metallogels) from recent publications. Various stimuli, such as light, temperature, pH, reduction/oxidation, enzymes, ions, glucose, ultrasound, magnetic fields, mechanical stress, solvent, voltage, and electrochemistry, have been combined to switch the functions of polymers. The polymer design, preparation, and function of multi-stimuli-responsive particles, films, and bulk gels are comprehensively discussed here.

  8. Can Conditioned Responses be Established in the Newborn Infant: 1971?

    Science.gov (United States)

    Sameroff, Arnold J.

    1971-01-01

    Evidence indicates that the newborn infant must first develop cognitive systems, through his experience with various stimuli, to differentiate each modality separately before he can integrate any two modalities in classical conditioning. (Author/NH)

  9. Lack of correlation between the amplitudes of TRP channel-mediated responses to weak and strong stimuli in intracellular Ca(2+) imaging experiments.

    Science.gov (United States)

    Alpizar, Yeranddy A; Sanchez, Alicia; Radwan, Ahmed; Radwan, Islam; Voets, Thomas; Talavera, Karel

    2013-11-01

    It is often observed in intracellular Ca(2+) imaging experiments that the amplitudes of the Ca(2+) signals elicited by newly characterized TRP agonists do not correlate with the amplitudes of the responses evoked subsequently by a specific potent agonist. We investigated this rather controversial phenomenon by first testing whether it is inherent to the comparison of the effects of weak and strong stimuli. Using five well-characterized TRP channel agonists in commonly used heterologous expression systems we found that the correlation between the amplitudes of the Ca(2+) signals triggered by two sequentially applied stimuli is only high when both stimuli are strong. Using mathematical simulations of intracellular Ca(2+) dynamics we illustrate that the innate heterogeneity in expression and functional properties of Ca(2+) extrusion (e.g. plasma membrane Ca(2+) ATPase) and influx (TRP channels) pathways across a cellular population is a sufficient condition for low correlation between the amplitude of Ca(2+) signals elicited by weak and strong stimuli. Taken together, our data demonstrate that this phenomenon is an expected outcome of intracellular Ca(2+) imaging experiments that cannot be taken as evidence for lack of specificity of low-efficacy stimuli, or as an indicator of the need of other cellular components for channel stimulation.

  10. Sexual and affective responses to same- and opposite-sex stimuli in heterosexual and homosexual men: assessment and manipulation of visual attention.

    Science.gov (United States)

    Samson, Lelia; Janssen, Erick

    2014-07-01

    Affective and cognitive factors play an important role in the activation and regulation of men's sexual arousal. Barlow (1986) argued that initial affective reactions determine the allocation of attention to sexual stimuli. We applied Barlow's model to our understanding of the role of sexual arousal in sexual orientation, where sexual arousal patterns have consistently been found to be congruent with self-reported orientation in men, but not in women. Visual attention of 28 heterosexual and 22 homosexual men to same- and opposite-sex erotic stimuli was assessed and experimentally-directed by means of a newly developed software application, while genital (penile rigidity) and affective responses (self-reported and physiological) were measured. In line with previous research, we found "category specificity" in men's sexual arousal, in that sexual responses were strongest to orientation-congruent stimuli. Also, both homosexual and heterosexual men experienced stronger sexual responses to conditions in which their attention was directed to sexual versus nonsexual content of orientation-congruent stimuli. Only homosexual men manifested higher sexual responses when their visual attention was directed towards the sexual content of orientation-incongruent stimuli. Heterosexual men experienced weaker positive and stronger negative affective responses to orientation-incongruent content, suggestive of potential avoidance or inhibitory mechanisms.

  11. Intact emotion facilitation for nonsocial stimuli in autism: is amygdala impairment in autism specific for social information?

    Science.gov (United States)

    South, Mikle; Ozonoff, Sally; Suchy, Yana; Kesner, Raymond P; McMahon, William M; Lainhart, Janet E

    2008-01-01

    Atypical amygdala development may play a key role in the emergence of social disability and other symptoms of autism (Baron-Cohen et al., 2000; Schultz, 2005). The mechanisms by which this may occur have received little attention, however, and most support from behavioral and imaging studies has been concerned with socially relevant stimuli such as faces. Given the complexity of amygdala function and its known role in many other emotional tasks, we examined whether individuals with autism would demonstrate impaired performance on several tasks that have been shown to require activation of the amygdala but that do not have any explicit social meaning. Relative to a typical comparison group matched for age and IQ, our sample of 37 adolescents and adults with autism (mean age=19.7 years) demonstrated equivalent facilitation for perception and learning of emotionally relevant stimuli. On each of four tasks, there were significant main effects of emotion condition on performance for both groups. Future research regarding atypical amygdala function and emotion processing in autism should consider whether the response to nonsocial emotion factors (including negative valence or high arousal) may be intact, despite difficulties in responding to socially relevant stimuli.

  12. Aversive and non-reward learning in the fire-bellied toad using familiar and unfamiliar prey stimuli

    Institute of Scientific and Technical Information of China (English)

    Ursula DICKE; Antje HEIDORN; Gerhard ROTH

    2011-01-01

    The present study investigated how snapping behavior toward familiar and unfamiliar prey is modified by reward omission and aversive conditioning in the fure-bellied toad Bombina orientalis.Toads were trained to snap at cricket images by rewarding them with live crickets.The task was learned,and the learning criterion (10 snapping responses within 2 minutes) was reached in all individuals investigated.Subsequent reward omission did not alter the frequency of snapping to the familiar cricket stimulus.Snapping decreased only in some individuals,when a mild foot shock was applied at snapping.However,at presentation of images of hitherto unfamiliar meal worms and foot-shock application at snapping to the stimulus,the majority of toads diminished snapping significantly.Snapping responses decreased more rapidly,when snapping at meal worms was not rewarded or a footshock was applied uncorrelated to the presentation of or snapping at meal worms.These results demonstrate that in toads familiarity and unfamiliarity of prey stimuli are important factors in aversive learning,because well-trained responses to familiar stimuli become immune against reward omission.Furthermore,at presentation of unfamiliar stimuli,omission of reward and uncorrelated footshock had a stronger aversive effect than correlated footshock [Current Zoology 57 (6):709-716,2011 ].

  13. Elicitation of the Acoustic Change Complex to Long-Duration Speech Stimuli in Four-Month-Old Infants.

    Science.gov (United States)

    Chen, Ke Heng; Small, Susan A

    2015-01-01

    The acoustic change complex (ACC) is an auditory-evoked potential elicited to changes within an ongoing stimulus that indicates discrimination at the level of the auditory cortex. Only a few studies to date have attempted to record ACCs in young infants. The purpose of the present study was to investigate the elicitation of ACCs to long-duration speech stimuli in English-learning 4-month-old infants. ACCs were elicited to consonant contrasts made up of two concatenated speech tokens. The stimuli included native dental-dental /dada/ and dental-labial /daba/ contrasts and a nonnative Hindi dental-retroflex /daDa/ contrast. Each consonant-vowel speech token was 410 ms in duration. Slow cortical responses were recorded to the onset of the stimulus and to the acoustic change from /da/ to either /ba/ or /Da/ within the stimulus with significantly prolonged latencies compared with adults. ACCs were reliably elicited for all stimulus conditions with more robust morphology compared with our previous findings using stimuli that were shorter in duration. The P1 amplitudes elicited to the acoustic change in /daba/ and /daDa/ were significantly larger compared to /dada/ supporting that the brain discriminated between the speech tokens. These findings provide further evidence for the use of ACCs as an index of discrimination ability.

  14. Elicitation of the Acoustic Change Complex to Long-Duration Speech Stimuli in Four-Month-Old Infants

    Directory of Open Access Journals (Sweden)

    Ke Heng Chen

    2015-01-01

    Full Text Available The acoustic change complex (ACC is an auditory-evoked potential elicited to changes within an ongoing stimulus that indicates discrimination at the level of the auditory cortex. Only a few studies to date have attempted to record ACCs in young infants. The purpose of the present study was to investigate the elicitation of ACCs to long-duration speech stimuli in English-learning 4-month-old infants. ACCs were elicited to consonant contrasts made up of two concatenated speech tokens. The stimuli included native dental-dental /dada/ and dental-labial /daba/ contrasts and a nonnative Hindi dental-retroflex /daDa/ contrast. Each consonant-vowel speech token was 410 ms in duration. Slow cortical responses were recorded to the onset of the stimulus and to the acoustic change from /da/ to either /ba/ or /Da/ within the stimulus with significantly prolonged latencies compared with adults. ACCs were reliably elicited for all stimulus conditions with more robust morphology compared with our previous findings using stimuli that were shorter in duration. The P1 amplitudes elicited to the acoustic change in /daba/ and /daDa/ were significantly larger compared to /dada/ supporting that the brain discriminated between the speech tokens. These findings provide further evidence for the use of ACCs as an index of discrimination ability.

  15. The Origins and Organization of Vertebrate Pavlovian Conditioning.

    Science.gov (United States)

    Fanselow, Michael S; Wassum, Kate M

    2015-11-09

    Pavlovian conditioning is the process by which we learn relationships between stimuli and thus constitutes a basic building block for how the brain constructs representations of the world. We first review the major concepts of Pavlovian conditioning and point out many of the pervasive misunderstandings about just what conditioning is. This brings us to a modern redefinition of conditioning as the process whereby experience with a conditional relationship between stimuli bestows these stimuli with the ability to promote adaptive behavior patterns that did not occur before the experience. Working from this framework, we provide an in-depth analysis of two examples, fear conditioning and food-based appetitive conditioning, which include a description of the only partially overlapping neural circuitry of each. We also describe how these circuits promote the basic characteristics that define Pavlovian conditioning, such as error-correction-driven regulation of learning.

  16. Color Discrimination Is Affected by Modulation of Luminance Noise in Pseudoisochromatic Stimuli

    Science.gov (United States)

    Cormenzana Méndez, Iñaki; Martín, Andrés; Charmichael, Teaire L.; Jacob, Mellina M.; Lacerda, Eliza M. C. B.; Gomes, Bruno D.; Fitzgerald, Malinda E. C.; Ventura, Dora F.; Silveira, Luiz C. L.; O'Donell, Beatriz M.; Souza, Givago S.

    2016-01-01

    Pseudoisochromatic stimuli have been widely used to evaluate color discrimination and to identify color vision deficits. Luminance noise is one of the stimulus parameters used to ensure that subject's response is due to their ability to discriminate target stimulus from the background based solely on the hue between the colors that compose such stimuli. We studied the influence of contrast modulation of the stimulus luminance noise on threshold and reaction time color discrimination. We evaluated color discrimination thresholds using the Cambridge Color Test (CCT) at six different stimulus mean luminances. Each mean luminance condition was tested using two protocols: constant absolute difference between maximum and minimum luminance of the luminance noise (constant delta protocol, CDP), and constant contrast modulation of the luminance noise (constant contrast protocol, CCP). MacAdam ellipses were fitted to the color discrimination thresholds in the CIE 1976 color space to quantify the color discrimination ellipses at threshold level. The same CDP and CCP protocols were applied in the experiment measuring RTs at three levels of stimulus mean luminance. The color threshold measurements show that for the CDP, ellipse areas decreased as a function of the mean luminance and they were significantly larger at the two lowest mean luminances, 10 cd/m2 and 13 cd/m2, compared to the highest one, 25 cd/m2. For the CCP, the ellipses areas also decreased as a function of the mean luminance, but there was no significant difference between ellipses areas estimated at six stimulus mean luminances. The exponent of the decrease of ellipse areas as a function of stimulus mean luminance was steeper in the CDP than CCP. Further, reaction time increased linearly with the reciprocal of the length of the chromatic vectors varying along the four chromatic half-axes. It decreased as a function of stimulus mean luminance in the CDP but not in the CCP. The findings indicated that visual

  17. Ghrelin regulates phasic dopamine and nucleus accumbens signaling evoked by food-predictive stimuli.

    Science.gov (United States)

    Cone, Jackson J; Roitman, Jamie D; Roitman, Mitchell F

    2015-06-01

    Environmental stimuli that signal food availability hold powerful sway over motivated behavior and promote feeding, in part, by activating the mesolimbic system. These food-predictive cues evoke brief (phasic) changes in nucleus accumbens (NAc) dopamine concentration and in the activity of individual NAc neurons. Phasic fluctuations in mesolimbic signaling have been directly linked to goal-directed behaviors, including behaviors elicited by food-predictive cues. Food-seeking behavior is also strongly influenced by physiological state (i.e., hunger vs. satiety). Ghrelin, a stomach hormone that crosses the blood-brain barrier, is linked to the perception of hunger and drives food intake, including intake potentiated by environmental cues. Notwithstanding, whether ghrelin regulates phasic mesolimbic signaling evoked by food-predictive stimuli is unknown. Here, rats underwent Pavlovian conditioning in which one cue predicted the delivery of rewarding food (CS+) and a second cue predicted nothing (CS-). After training, we measured the effect of ghrelin infused into the lateral ventricle (LV) on sub-second fluctuations in NAc dopamine using fast-scan cyclic voltammetry and individual NAc neuron activity using in vivo electrophysiology in separate groups of rats. LV ghrelin augmented both phasic dopamine and phasic increases in the activity of NAc neurons evoked by the CS+. Importantly, ghrelin did not affect the dopamine nor NAc neuron response to the CS-, suggesting that ghrelin selectively modulated mesolimbic signaling evoked by motivationally significant stimuli. These data demonstrate that ghrelin, a hunger signal linked to physiological state, can regulate cue-evoked mesolimbic signals that underlie food-directed behaviors. Cues that predict food availability powerfully regulate food-seeking behavior. Here we show that cue-evoked changes in both nucleus accumbens (NAc) dopamine (DA) and NAc cell activity are modulated by intra-cranial infusions of the stomach

  18. Individual variation in habituation: behaviour over time toward different stimuli in threespine sticklebacks (Gasterosteus aculeatus)

    OpenAIRE

    Bell, Alison M.; Peeke, Harman V.S.

    2012-01-01

    Habituation, or the relatively permanent waning of a response as a result of repeated stimulation, is a form of behavioural plasticity that allows animals to filter out irrelevant stimuli and to focus selectively on important stimuli. Individuals that fail to habituate might be at a disadvantage if they continue to respond to irrelevant stimuli; therefore, habituation can have adaptive significance. In this study we compared rates of behaviour over time toward three different ecologically-rel...

  19. The effects of visual stimuli on EEG mu rhythms in healthy adults

    Science.gov (United States)

    Kim, JiYoung; Kim, SeongYoel

    2016-01-01

    [Purpose] Several action observation/imagery training studies have been conducted in patients with limited physical activity showing improvements in motor function. However, most studies compared effects of action observation and imagery, so little is known about the changes caused by subsequent observation of target objects. Moreover, few studies analyzed brain wave changes in the EEG mu rhythm. [Subjects and Methods] Eighteen healthy female adults participated in this study, and were divided into two groups: ‘Visual Stimuli’ and ‘Non-Visual Stimuli’. EEG amplitude in the 8–13 Hz frequency band over the sensorimotor cortex was evaluated. [Results] Significant mu suppression was obtained in the action observation trials. Mu power showed a main effect of visual stimuli, with decreased power during action observation, and increased power post-observation in both conditions. Comparing the ‘Visual Stimuli’ and ‘Non-Visual Stimuli’ conditions during the post-observation period, mu power demonstrated a greater increase in the ‘Non-Visual Stimuli’ condition. Furthermore, mu power was lower post-observation than pre-observation. [Conclusion] These results show the effects of visual input between maintaining target objects and no visual input, and their relevance to modulations of the mirror neuron system. It also suggests that greater visual input may be more effective for cognitive rehabilitation. PMID:27390408

  20. Transient rheology of stimuli responsive hydrogels: Integrating microrheology and microfluidics

    Science.gov (United States)

    Sato, Jun

    Stimuli-responsive hydrogels have diverse potential applications in the field of drug delivery, tissue engineering, agriculture, cosmetics, gene therapy, and as sensors and actuators due to their unique responsiveness to external signals, such as pH, temperature, and ionic strength. Understanding the responsiveness of hydrogel structure and rheology to these stimuli is essential for designing materials with desirable performance. However, no instrumentation and well-defined methodology are available to characterize the structural and rheological responses to rapid solvent changes. In this thesis, a new microrheology set-up is described, which allows us to quantitatively measure the transient rheological properties and microstructure of a variety of solvent-responsive complex fluids. The device was constructed by integrating particle tracking microrheology and microfluidics and offers unique experimental capabilities for performing solvent-reponse measurements on soft fragile materials without applying external shear forces. Transient analysis methods to quantitatively obtain rheological properties were also constructed, and guidelines for the trade-off between statistical validity and temporal resolution were developed to accurately capture physical transitions. Employing the new device and methodology, we successfully quantified the transient rheological and microstructural responses during gel formation and break-up, and viscosity changes of solvent-responsive complex fluids. The analysis method was expanded for heterogeneous samples, incorporating methods to quantify the microrheology of samples with broad distributions of individual particle dynamics. Transient microrheology measurements of fragile, heterogeneous, self-assembled block copolypeptide hydrogels revealed that solvent exchange via convective mixing and dialysis can lead to significantly different gel properties and that commonly applied sample preparation protocols for the characterization of soft

  1. Social facilitation of insect reproduction with motor-driven tactile stimuli

    National Research Council Canada - National Science Library

    Uzsák, Adrienn; Dieffenderfer, James; Bozkurt, Alper; Schal, Coby

    2014-01-01

    ..., and thermo-, hygro- and mechanoreception. The antennae, being the anteriormost sensory appendages, play a prominent role in social interactions with conspecifics that involve primarily chemosensory and tactile stimuli...

  2. The Occurrence Rate of the Fission Illusion Differs Depending on the Complexity of Visual Stimuli

    Directory of Open Access Journals (Sweden)

    Yasuhiro Takeshima

    2011-10-01

    Full Text Available A fission illusion (also named a double—flash illusion is a famous phenomenon of audio-visual interaction, in which a single brief flash is perceived as two flashes when presented simultaneously with two brief beeps (Shames, Kamitani, & Shimojo, 2000; 2002. The fission illusion has been investigated using relatively simple visual stimuli like single circle. Thus the illusion has not been examined by using complex visual stimuli. Markovic & Gvozdenovic (2001 reported that the processing of complex visual stimuli tends to be delayed. Therefore, the complexity of visual stimuli may affect the occurrence rate of the fission illusion, since this illusion is generated in the process that copes with visual and auditory stimuli in a short time. The present study examined the differences in illusory occurrence rates by manipulating the complexity of visual stimuli. We used the patterns proposed by Garner & Clement (1963 to control the complexity. The results indicated that it was more difficult to induce the fission illusion by using complex visual stimuli than it was by using simple stimuli. Thus, the present study suggested that the occurrence rate of the fission illusion differed depending on the perceptual efficiency in the coding process of visual stimuli. This study was supported by Grant-in-Aid for Specifically Promoted Research (No. 19001004.

  3. Alleged Approach-Avoidance Conflict for Food Stimuli in Binge Eating Disorder.

    Directory of Open Access Journals (Sweden)

    Elisabeth J Leehr

    Full Text Available Food stimuli are omnipresent and naturally primary reinforcing stimuli. One explanation for the intake of high amounts of food in binge eating disorder (BED is a deviant valuation process. Valuation of food stimuli is supposed to influence approach or avoidance behaviour towards food. Focusing on self-reported and indirect (facial electromyography valuation process, motivational aspects in the processing of food stimuli were investigated.We compared an overweight sample with BED (BED+ with an overweight sample without BED (BED- and with normal weight controls (NWC regarding their self-reported and indirect (via facial electromyography valuation of food versus non-food stimuli.Regarding the self-reported valuation, the BED+ sample showed a significantly stronger food-bias compared to the BED- sample, as food stimuli were rated as significantly more positive than the non-food stimuli in the BED+ sample. This self-reported valuation pattern could not be displayed in the indirect valuation. Food stimuli evoked negative indirect valuation in all groups. The BED+ sample showed the plainest approach-avoidance conflict marked by a diverging self-reported (positive and indirect (negative valuation of food stimuli.BED+ showed a deviant self-reported valuation of food as compared to BED-. The valuation process of the BED+ sample seems to be characterized by a motivational ambivalence. This ambivalence should be subject of further studies and may be of potential use for therapeutic interventions.

  4. Acute stress-induced cortisol elevations mediate reward system activity during subconscious processing of sexual stimuli.

    Science.gov (United States)

    Oei, Nicole Y L; Both, Stephanie; van Heemst, Diana; van der Grond, Jeroen

    2014-01-01

    Stress is thought to alter motivational processes by increasing dopamine (DA) secretion in the brain's "reward system", and its key region, the nucleus accumbens (NAcc). However, stress studies using functional magnetic resonance imaging (fMRI), mainly found evidence for stress-induced decreases in NAcc responsiveness toward reward cues. Results from both animal and human PET studies indicate that the stress hormone cortisol may be crucial in the interaction between stress and dopaminergic actions. In the present study we therefore investigated whether cortisol mediated the effect of stress on DA-related responses to -subliminal-presentation of reward cues using the Trier Social Stress Test (TSST), which is known to reliably enhance cortisol levels. Young healthy males (n = 37) were randomly assigned to the TSST or control condition. After stress induction, brain activation was assessed using fMRI during a backward-masking paradigm in which potentially rewarding (sexual), emotionally negative and neutral stimuli were presented subliminally, masked by pictures of inanimate objects. A region of interest analysis showed that stress decreased activation in the NAcc in response to masked sexual cues (voxel-corrected, pcortisol levels were related to stronger NAcc activation, showing that cortisol acted as a suppressor variable in the negative relation between stress and NAcc activation. The present findings indicate that cortisol is crucially involved in the relation between stress and the responsiveness of the reward system. Although generally stress decreases activation in the NAcc in response to rewarding stimuli, high stress-induced cortisol levels suppress this relation, and are associated with stronger NAcc activation. Individuals with a high cortisol response to stress might on one hand be protected against reductions in reward sensitivity, which has been linked to anhedonia and depression, but they may ultimately be more vulnerable to increased reward

  5. Extracellular microvesicle production by human eosinophils activated by “inflammatory” stimuli

    Directory of Open Access Journals (Sweden)

    Praveen Akuthota

    2016-10-01

    Full Text Available A key function of human eosinophils is to secrete cytokines, chemokines and cationic proteins, trafficking and releasing these mediators for roles in inflammation and other immune responses. Eosinophil activation leads to secretion of pre-synthesized granule-stored mediators through different mechanisms, but the ability of eosinophils to secrete extracellular vesicles (EVs, very small vesicles with preserved membrane topology, is still poorly understood. In the present work, we sought to identify and characterize EVs released from human eosinophils during different conditions: after a culturing period or after isolation and stimulation with inflammatory stimuli, which are known to induce eosinophil activation and secretion: CCL11 (eotaxin-1 and tumor necrosis factor alpha (TNF-α. EV production was investigated by nanoscale flow cytometry, conventional transmission electron microscopy (TEM and pre-embedding immunonanogold EM. The tetraspanins CD63 and CD9 were used as EV biomarkers for both flow cytometry and ultrastructural immunolabeling. Nanoscale flow cytometry showed that human eosinophils produce EVs in culture and that a population of EVs expressed detectable CD9, while CD63 was not consistently detected. When eosinophils were stimulated immediately after isolation and analyzed by TEM, EVs were clearly identified as microvesicles (MVsoutwardly budding off the plasma membrane. Both CCL11 and TNF-α induced significant increases of MVs compared to unstimulated cells.TNF-α induced amplified release of MVs more than CCL11. Eosinophil MV diameters varied from 20-1000 nm. Immunonanogold EM revealed clear immunolabeling for CD63 and CD9 on eosinophil MVs, although not all MVs were labeled. Altogether, we identified, for the first time, that human eosinophils secrete MVs and that this production increases in response to inflammatory stimuli. This is important to understand the complex secretory activities of eosinophils underlying immune

  6. SA-I Mechanoreceptor Position in Fingertip Skin May Impact Sensitivity to Edge Stimuli

    Directory of Open Access Journals (Sweden)

    Gregory J. Gerling

    2010-01-01

    Full Text Available Background: The skin plays a role in conditioning mechanical indentation into distributions of stress/strain that mechanoreceptors convert into neural signals. Solid mechanics methods have modelled the skin to predict the in vivo neural response from mechanoreceptors. Despite their promise, current models cannot explain the role that anatomical positioning and receptor organ morphology play in producing differences in neural response. This work hypothesises that the skin's intermediate ridges may help explain, in part, the sensitivity of slowly adapting type I (SA-I mechanoreceptors to edge stimuli. Method: Two finite-element models of the fingertip were built, validated and used to analyse the functionality of the intermediate ridges. One of the two-dimensional, cross-sectional models included intermediate ridges, while the other did not. The analysis sought to determine if intermediate ridges (1 increase the magnitude of strain energy density (SED near the SA-I location and (2 help differentiate one 2.0-mm indenter from two 0.5-mm wide indenters with a 1.0-mm gap. Results: Higher concentrations of SED were found near the tips of the intermediate ridges, the anatomical location that coincides with the SA-I receptors. This first result suggested that the location of the SA-Is in the stiffer epidermal tissue helps magnify their response to edge stimuli. The second result was that both models were equally capable of predicting the spatial structure within the in vivo neural responses, and therefore the addition of intermediate ridges did not help in differentiating the indenters. Conclusion: The finding, a 15%–35% increase in response when the sampling point lies within the stiffer tissue at the same depth, seeks to inform the positioning of force sensors in robotic skin substrates.

  7. Neuronal Analogues of Conditioning Paradigms

    Science.gov (United States)

    1984-04-24

    Although the mechanisms of interneuronal communication have been well established, the changes underlying most forms of learning have thus far eluded...stimulating electrodes on one of the connectives was adjusted so as to produce a small excitatory postsynaptic potential ( EPSP ) in the impaled cell...two stimuli would constitute a neuronal analogue of conditioning by producing an increased EPSP in response to the test stimulus alone. If so, then

  8. Pattern transformations in periodic cellular solids under external stimuli

    Science.gov (United States)

    Zhang, K.; Zhao, X. W.; Duan, H. L.; Karihaloo, B. L.; Wang, J.

    2011-04-01

    The structural patterns of periodic cellular materials play an important role in their properties. Here, we investigate how these patterns transform dramatically under external stimuli in simple periodic cellular structures that include a nanotube bundle and a millimeter-size plastic straw bundle. Under gradual hydrostatic straining up to 20%, the cross-section of the single walled carbon nanotube bundle undergoes several pattern transformations, while an amazing new hexagram pattern is triggered from the circular shape when the strain of 20% is applied suddenly in one step. Similar to the nanotube bundle, the circular plastic straw bundle is transformed into a hexagonal pattern on heating by conduction through a baseplate but into a hexagram pattern when heated by convection. Besides the well-known elastic buckling, we find other mechanisms of pattern transformation at different scales; these include the minimization of the surface energy at the macroscale or of the van der Waals energy at the nanoscale and the competition between the elastic energy of deformation and either the surface energy at the macroscale or the van der Waals energy at the nanoscale. The studies of the pattern transformations of periodic porous materials offer new insights into the fabrication of novel materials and devices with tailored properties.

  9. Exogenous (automatic) attention to emotional stimuli: a review.

    Science.gov (United States)

    Carretié, Luis

    2014-12-01

    Current knowledge on the architecture of exogenous attention (also called automatic, bottom-up, or stimulus-driven attention, among other terms) has been mainly obtained from studies employing neutral, anodyne stimuli. Since, from an evolutionary perspective, exogenous attention can be understood as an adaptive tool for rapidly detecting salient events, reorienting processing resources to them, and enhancing processing mechanisms, emotional events (which are, by definition, salient for the individual) would seem crucial to a comprehensive understanding of this process. This review, focusing on the visual modality, describes 55 experiments in which both emotional and neutral irrelevant distractors are presented at the same time as ongoing task targets. Qualitative and, when possible, meta-analytic descriptions of results are provided. The most conspicuous result is that, as confirmed by behavioral and/or neural indices, emotional distractors capture exogenous attention to a significantly greater extent than do neutral distractors. The modulatory effects of the nature of distractors capturing attention, of the ongoing task characteristics, and of individual differences, previously proposed as mediating factors, are also described. Additionally, studies reviewed here provide temporal and spatial information-partially absent in traditional cognitive models-on the neural basis of preattention/evaluation, reorienting, and sensory amplification, the main subprocesses involved in exogenous attention. A model integrating these different levels of information is proposed. The present review, which reveals that there are several key issues for which experimental data are surprisingly scarce, confirms the relevance of including emotional distractors in studies on exogenous attention.

  10. Peculiarities of hearing impairment depending on interaction with acoustic stimuli

    Science.gov (United States)

    Myshchenko, Iryna; Nazarenko, Vasyl; Kolganov, Anatoliy; Tereshchenko, Pavlo

    2015-01-01

    Aims: The functional state of the auditory analyzer of several operators groups was study. The objective of this study was to determine some characteristics of hearing impairment in relation with features of acoustic stimuli and informative significance of noise. Materials and Methods: 236 employees (middle age 35.4 ± 0.74 years) were divided into four groups according to features of noise perception at the workplaces. The levels of permanent shifts of acoustic thresholds were estimated using audiometric method. Statistical Analysis Used: Common statistical methods were used in research. Mean quantity and mean absolute errors were calculated. Statistical significance between operators' groups was calculated with 0.05 confidential intervals. Results: The peculiarities of hearing impairment in observed groups were different. Operators differentiating acoustic signals had peak of hearing impairment in the field of language frequencies, while the employees who work with noise background at the workplaces had maximal hearing threshold on the 4000 Hz frequency (P ≤ 0.05). Conclusions: Hearing impairment depends both on energy and human interaction with acoustic irritant. The distinctions in hearing impairment may be related with the necessity of recognizing of acoustic signals and their frequency characteristics. PMID:26957812

  11. Objective perimetry in glaucoma: recent advances with multifocal stimuli.

    Science.gov (United States)

    Graham, S L; Klistorner, A; Grigg, J R; Billson, F A

    1999-06-01

    The introduction of multifocal stimulus recording has enhanced our ability to examine the human visual field with electrophysiologic techniques. We have adapted the multifocal pattern visual evoked potential (PVEP) to detect visual field loss. In glaucoma patients we sought to determine the extent to which the PVEP amplitudes correlate with perimetric thresholds. Multifocal pseudorandomly alternated pattern stimuli, which were cortically scaled in size, were presented with use of the VERIS-Scientific system. Bipolar occipital straddle electrode positions were used. The visual field up to 25 degrees of eccentricity was investigated. Forty-three glaucoma patients with reproducible visual field defects were tested. The bipolar PVEP corresponded well with Humphrey visual field defects, showing loss of signal in the scotoma area. For Humphrey quadrant threshold totals and PVEP quadrant amplitudes, the correlation coefficient was strong (r = 0.49, P < 0.0001). The multifocal PVEP demonstrates good correspondence with the topography of the visual field. This technique represents the first practical application of the multifocal PVEP to objective detection of visual field defects in glaucoma.

  12. Undetected changes in visible stimuli influence subsequent decisions.

    Science.gov (United States)

    Laloyaux, Cédric; Devue, Christel; Doyen, Stéphane; David, Elodie; Cleeremans, Axel

    2008-09-01

    Change blindness-our inability to detect changes in a stimulus-occurs even when the change takes place gradually, without any disruption [Simons, D. J., Franconeri, S. L., & Reimer, R. L. (2000). Change blindness in the absence of a visual disruption. Perception, 29(10), 1143-1154]. Such gradual changes are more difficult to detect than changes that involve a disruption. Using this method, David et al. [David, E., Laloyaux, C., Devue, C., & Cleeremans, A. (in press). Change blindness to gradual changes in facial expressions. Psychologica Belgica] recently showed substantial blindness to changes that involve facial expressions of emotion. In this experiment, we show that people who failed to detect any change in the displays were (1) nevertheless influenced by the changing information in subsequent recognition decisions about which facial expression they had seen, and (2) that their confidence in their decisions was lower after exposure to changing vs. static displays. The findings therefore support the notion that undetected changes that occur in highly salient stimuli may be causally efficacious and influence subsequent behavior. Implications concerning the nature of the representations associated with undetected changes are discussed.

  13. Visual anticipatory information modulates multisensory interactions of artificial audiovisual stimuli.

    Science.gov (United States)

    Vroomen, Jean; Stekelenburg, Jeroen J

    2010-07-01

    The neural activity of speech sound processing (the N1 component of the auditory ERP) can be suppressed if a speech sound is accompanied by concordant lip movements. Here we demonstrate that this audiovisual interaction is neither speech specific nor linked to humanlike actions but can be observed with artificial stimuli if their timing is made predictable. In Experiment 1, a pure tone synchronized with a deformation of a rectangle induced a smaller auditory N1 than auditory-only presentations if the temporal occurrence of this audiovisual event was made predictable by two moving disks that touched the rectangle. Local autoregressive average source estimation indicated that this audiovisual interaction may be related to integrative processing in auditory areas. When the moving disks did not precede the audiovisual stimulus--making the onset unpredictable--there was no N1 reduction. In Experiment 2, the predictability of the leading visual signal was manipulated by introducing a temporal asynchrony between the audiovisual event and the collision of moving disks. Audiovisual events occurred either at the moment, before (too "early"), or after (too "late") the disks collided on the rectangle. When asynchronies varied from trial to trial--rendering the moving disks unreliable temporal predictors of the audiovisual event--the N1 reduction was abolished. These results demonstrate that the N1 suppression is induced by visual information that both precedes and reliably predicts audiovisual onset, without a necessary link to human action-related neural mechanisms.

  14. External stimuli mediate collective rhythms: artificial control strategies.

    Directory of Open Access Journals (Sweden)

    Tianshou Zhou

    Full Text Available The artificial intervention of biological rhythms remains an exciting challenge. Here, we proposed artificial control strategies that were developed to mediate the collective rhythms emerging in multicellular structures. Based on noisy repressilators and by injecting a periodic control amount to the extracellular medium, we introduced two typical kinds of control models. In one, there are information exchanges among cells, where signaling molecules receive the injected stimulus that freely diffuses toward/from the intercellular medium. In the other, there is no information exchange among cells, but signaling molecules also receive the stimulus that directionally diffuses into each cell from the common environment. We uncovered physical mechanisms for how the stimulus induces, enhances or ruins collective rhythms. We found that only when the extrinsic period is close to an integer multiplicity of the averaged intrinsic period can the collective behaviors be induced/enhanced; otherwise, the stimulus possibly ruins the achieved collective behaviors. Such entrainment properties of these oscillators to external signals would be exploited by realistic living cells to sense external signals. Our results not only provide a new perspective to the understanding of the interplays between extrinsic stimuli and intrinsic physiological rhythms, but also would lead to the development of medical therapies or devices.

  15. Impaired autonomic responses to emotional stimuli in autoimmune limbic encephalitis

    Directory of Open Access Journals (Sweden)

    Olga eSchröder

    2015-11-01

    Full Text Available Limbic encephalitis (LE is an autoimmune-mediated disorder that affects structures of the limbic system, in particular the amygdala. The amygdala constitutes a brain area substantial for processing of emotional, especially fear-related signals. The amygdala is also involved in neuroendocrine and autonomic functions, including skin conductance responses (SCRs to emotionally arousing stimuli. This study investigates behavioral and autonomic responses to discrete emotion-evoking and neutral film clips in a patient suffering from LE associated with contactin-associated protein-2 (CASPR2-antibodies as compared to a healthy control group. Results show a lack of SCRs in the patient while watching the film clips, with significant differences compared to healthy controls in the case of fear-inducing videos. There was no comparable impairment in behavioral data (emotion report, valence and arousal ratings. The results point to a defective modulation of sympathetic responses during emotional stimulation in patients with LE, probably due to impaired functioning of the amygdala.

  16. Volumetric measurement of tank volume

    Science.gov (United States)

    Walter, Richard T. (Inventor); Vanbuskirk, Paul D. (Inventor); Weber, William F. (Inventor); Froebel, Richard C. (Inventor)

    1991-01-01

    A method is disclosed for determining the volume of compressible gas in a system including incompressible substances in a zero-gravity environment consisting of measuring the change in pressure (delta P) for a known volume change rate (delta V/delta t) in the polytrophic region between isothermal and adiabatic conditions. The measurements are utilized in an idealized formula for determining the change in isothermal pressure (delta P sub iso) for the gas. From the isothermal pressure change (delta iso) the gas volume is obtained. The method is also applicable to determination of gas volume by utilizing work (W) in the compression process. In a passive system, the relationship of specific densities can be obtained.

  17. Mechanical stimuli of skeletal muscle: implications on mTOR/p70s6k and protein synthesis.

    Science.gov (United States)

    Zanchi, Nelo Eidy; Lancha, Antonio Herbert

    2008-02-01

    The skeletal muscle is a tissue with adaptive properties which are essential to the survival of many species. When mechanically stimulated it is liable to undergo remodeling, namely, changes in its mass/volume resulting mainly from myofibrillar protein accumulation. The mTOR pathway (mammalian target of rapamycin) via its effector p70s6k (ribosomal protein kinase S6) has been reported to be of importance to the control of skeletal muscle mass, particularly under mechanical stimulation. However, not all mechanical stimuli are capable of activating this pathway, and among those who are, there are differences in the activation magnitude. Likewise, not all skeletal muscle fibers respond to the same extent to mechanical stimulation. Such evidences suggest specific mechanical stimuli through appropriate cellular signaling to be responsible for the final physiological response, namely, the accumulation of myofibrillar protein. Lately, after the mTOR signaling pathway has been acknowledged as of importance for remodeling, the interest for the mechanical/chemical mediators capable of activating it has increased. Apart from the already known MGF (mechano growth factor), some other mediators such as phosphatidic acid (PA) have been identified. This review article comprises and discusses relevant information on the mechano-chemical transduction of the pathway mTOR, with special emphasis on the muscle protein synthesis.

  18. Visual cortex and auditory cortex activation in early binocularly blind macaques: A BOLD-fMRI study using auditory stimuli.

    Science.gov (United States)

    Wang, Rong; Wu, Lingjie; Tang, Zuohua; Sun, Xinghuai; Feng, Xiaoyuan; Tang, Weijun; Qian, Wen; Wang, Jie; Jin, Lixin; Zhong, Yufeng; Xiao, Zebin

    2017-04-15

    Cross-modal plasticity within the visual and auditory cortices of early binocularly blind macaques is not well studied. In this study, four healthy neonatal macaques were assigned to group A (control group) or group B (binocularly blind group). Sixteen months later, blood oxygenation level-dependent functional imaging (BOLD-fMRI) was conducted to examine the activation in the visual and auditory cortices of each macaque while being tested using pure tones as auditory stimuli. The changes in the BOLD response in the visual and auditory cortices of all macaques were compared with immunofluorescence staining findings. Compared with group A, greater BOLD activity was observed in the bilateral visual cortices of group B, and this effect was particularly obvious in the right visual cortex. In addition, more activated volumes were found in the bilateral auditory cortices of group B than of group A, especially in the right auditory cortex. These findings were consistent with the fact that there were more c-Fos-positive cells in the bilateral visual and auditory cortices of group B compared with group A (p visual cortices of binocularly blind macaques can be reorganized to process auditory stimuli after visual deprivation, and this effect is more obvious in the right than the left visual cortex. These results indicate the establishment of cross-modal plasticity within the visual and auditory cortices.

  19. Procedure to validate sexual stimuli: reliability and validity of a set of sexual stimuli in a sample of young colombian heterosexual males

    OpenAIRE

    Pablo Vallejo-Medina; Franklin Soler; Mayra, Gomez-Lugo; Alejandro, Saavedra-Roa; Laurent, Marchal-Bertrand

    2017-01-01

    Penile plethysmography – or phallometric assessment – is a very relevant evaluation for sexual health. The objective of this research is to suggest a guideline to validate sexual stimuli and validate a set of sexual stimuli to assess “normative” sexual behavior in Colombian young heterosexual men. Six videos of 3:15 minute-long were used. A total of 24 men were assessed. Objective sexual arousal, the International Index of Erectile Function-5, Self-Assessment Manikin, Multidimensi...

  20. Disruption of Responding Maintained by Conditioned Reinforcement: Alterations in Response-Conditioned-Reinforcer Relations

    Science.gov (United States)

    Lieving, Gregory A.; Reilly, Mark P.; Lattal, Kennon A.

    2006-01-01

    An observing procedure was used to investigate the effects of alterations in response-conditioned-reinforcer relations on observing. Pigeons responded to produce schedule-correlated stimuli paired with the availability of food or extinction. The contingency between observing responses and conditioned reinforcement was altered in three experiments.…

  1. Presentation of Aural Stimuli to Newborns and Premature Infants: An Audiological Perspective.

    Science.gov (United States)

    Cassidy

    1999-01-01

    The purpose of this study was twofold: (a) to examine extant research in the field of music with premature and full term infants in order to identify protocols being used in the presentation of musical stimuli to neonates and (b) to use knowledge gleaned from audiology as a basis for suggesting a standardized protocol for use of musical stimuli with infants. Articles considered appropriate for inclusion in the analysis met the following criteria: (a) presented data for the effects of music on a dependent measure, (b) had subjects who were identified as either premature or term newborns receiving treatment after birth and prior to discharge from the hospital, and (c) used music for some or all of the aural stimuli. Articles (N = 20) were categorized by demographic information, types of aural stimuli, independent variables, dependent measures, and protocol used to present the musical stimuli. Of primary importance to this study was the protocol used in each study to present musical stimuli. Data regarding total duration of stimuli per day, longest duration of stimuli per day, method of stimuli presentation, placement of speakers, decibel level of stimuli, and where;he decibel level was measured reveal that there is no standard protocol being followed with regard to the presentation of aural stimuli. Recommendations include future research on (a) determining a minimum gestational age where music therapy may be appropriate, (b) determining the frequency spectrum perceived by a premature infant, (c) determining the decibel levels reaching the ear drum and assessing appropriate levels for minimum stimulation with maximum results, and (d) carefully considering the method of stimulus presentation as it will have an impact on the decibel level reaching the ear drum of these infants.

  2. Worry-inducing stimuli in an aversive Go/NoGo task enhance reactive control in individuals with lower trait-anxiety.

    Science.gov (United States)

    Leue, Anja; Rodilla, Carmen Cano; Beauducel, André

    2017-02-17

    This study relates predictions on reactive and proactive cognitive control to findings on anxious apprehension/worry and ERN/Ne. We investigated whether worry-inducing stimuli in an aversive performance setting lead to a more pronounced increase of the ERN/Ne in individuals with lower anxious apprehension/worry. We also explored the N2 amplitude in the context of worry-inducing stimuli. Fifty-eight participants performed an extended Go/NoGo task. A neutral or fearful face was presented at the beginning of each trial, with the fearful face as a worry-inducing, distracting stimulus. In an aversive feedback condition, aversive feedback was provided for false or too slow responses. We found a more pronounced decrease of the ERN/Ne after worry-inducing stimuli compared to neutral stimuli in participants with lower anxious apprehension/worry. Moreover, less pronounced N2 amplitudes were associated with shorter reaction times in the aversive feedback condition. Implications for future research on error monitoring and trait-anxiety are discussed.

  3. Intersubject information mapping: revealing canonical representations of complex natural stimuli

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    Nikolaus Kriegeskorte

    2015-03-01

    Full Text Available Real-world time-continuous stimuli such as video promise greater naturalism for studies of brain function. However, modeling the stimulus variation is challenging and introduces a bias in favor of particular descriptive dimensions. Alternatively, we can look for brain regions whose signal is correlated between subjects, essentially using one subject to model another. Intersubject correlation mapping (ICM allows us to find brain regions driven in a canonical manner across subjects by a complex natural stimulus. However, it requires a direct voxel-to-voxel match between the spatiotemporal activity patterns and is thus only sensitive to common activations sufficiently extended to match up in Talairach space (or in an alternative, e.g. cortical-surface-based, common brain space. Here we introduce the more general approach of intersubject information mapping (IIM. For each brain region, IIM determines how much information is shared between the subjects' local spatiotemporal activity patterns. We estimate the intersubject mutual information using canonical correlation analysis applied to voxels within a spherical searchlight centered on each voxel in turn. The intersubject information estimate is invariant to linear transforms including spatial rearrangement of the voxels within the searchlight. This invariance to local encoding will be crucial in exploring fine-grained brain representations, which cannot be matched up in a common space and, more fundamentally, might be unique to each individual – like fingerprints. IIM yields a continuous brain map, which reflects intersubject information in fine-grained patterns. Performed on data from functional magnetic resonance imaging (fMRI of subjects viewing the same television show, IIM and ICM both highlighted sensory representations, including primary visual and auditory cortices. However, IIM revealed additional regions in higher association cortices, namely temporal pole and orbitofrontal cortex. These

  4. Specificity of brain reactions to second-order visual stimuli.

    Science.gov (United States)

    Babenko, Vitaly V; Ermakov, Pavel N

    2015-01-01

    The second-order visual mechanisms perform the operation of integrating the spatially distributed local visual information. Their organization is traditionally considered within the framework of the filter-rectify-filter model. These are the second-order filters that provide the ability to detect texture gradients. However, the question of the mechanisms' selectivity to the modulation dimension remains open. The aim of this investigation is to answer the above question by using visual evoked potentials (VEPs). Stimuli were textures consisting of staggered Gabor patches. The base texture was nonmodulated (NM). Three other textures represented the base texture which was sinusoidally modulated in different dimensions: contrast, orientation, or spatial frequency. EEG was recorded with 20 electrodes. VEPs of 500 ms duration were obtained for each of the four textures. After that, VEP to the NM texture was subtracted from VEP to each modulated texture. As a result, three different waves (d-waves) were obtained for each electrode site. Each d-wave was then averaged across all the 48 observers. The revealed d-waves have a latency of about 200 ms and, in our opinion, reflect the second-order filters reactivation through the feedback connection. The d-waves for different modulation dimensions were compared with each other in time, amplitude, topography, and localization of the sources of activity that causes the d-wave (with sLORETA). We proceeded from the assumption that the d-wave (its first component) represents functioning of the second-order visual mechanisms and activity changes at the following processing stages. It was found that the d-waves for different modulation dimensions significantly differ in all parameters. The obtained results indicate that the spatial modulations of different texture parameters caused specific changes in the brain activity, which could be evidence supporting the specificity of the second-order visual mechanisms to modulation dimension.

  5. Design, challenge, and promise of stimuli-responsive nanoantibiotics

    Science.gov (United States)

    Edson, Julius A.; Kwon, Young Jik

    2016-10-01

    Over the past few years, there have been calls for novel antimicrobials to combat the rise of drug-resistant bacteria. While some promising new discoveries have met this call, it is not nearly enough. The major problem is that although these new promising antimicrobials serve as a short-term solution, they lack the potential to provide a long-term solution. The conventional method of creating new antibiotics relies heavily on the discovery of an antimicrobial compound from another microbe. This paradigm of development is flawed due to the fact that microbes can easily transfer a resistant mechanism if faced with an environmental pressure. Furthermore, there has been some evidence to indicate that the environment of the microbe can provide a hint as to their virulence. Because of this, the use of materials with antimicrobial properties has been garnering interest. Nanoantibiotics, (nAbts), provide a new way to circumvent the current paradigm of antimicrobial discovery and presents a novel mechanism of attack not found in microbes yet; which may lead to a longer-term solution against drug-resistance formation. This allows for environment-specific activation and efficacy of the nAbts but may also open up and create new design methods for various applications. These nAbts provide promise, but there is still ample work to be done in their development. This review looks at possible ways of improving and optimizing nAbts by making them stimuli-responsive, then consider the challenges ahead, and industrial applications.[Figure not available: see fulltext.

  6. Multiple distinct stimuli increase measured nucleosome occupancy around human promoters.

    Directory of Open Access Journals (Sweden)

    Chuong D Pham

    Full Text Available Nucleosomes can block access to transcription factors. Thus the precise localization of nucleosomes relative to transcription start sites and other factor binding sites is expected to be a critical component of transcriptional regulation. Recently developed microarray approaches have allowed the rapid mapping of nucleosome positions over hundreds of kilobases (kb of human genomic DNA, although these approaches have not yet been widely used to measure chromatin changes associated with changes in transcription. Here, we use custom tiling microarrays to reveal changes in nucleosome positions and abundance that occur when hormone-bound glucocorticoid receptor (GR binds to sites near target gene promoters in human osteosarcoma cells. The most striking change is an increase in measured nucleosome occupancy at sites spanning ∼1 kb upstream and downstream of transcription start sites, which occurs one hour after addition of hormone, but is lost at 4 hours. Unexpectedly, this increase was seen both on GR-regulated and GR-non-regulated genes. In addition, the human SWI/SNF chromatin remodeling factor (a GR co-activator was found to be important for increased occupancy upon hormone treatment and also for low nucleosome occupancy without hormone. Most surprisingly, similar increases in nucleosome occupancy were also seen on both regulated and non-regulated promoters during differentiation of human myeloid leukemia cells and upon activation of human CD4+ T-cells. These results indicate that dramatic changes in chromatin structure over ∼2 kb of human promoters may occur genomewide and in response to a variety of stimuli, and suggest novel models for transcriptional regulation.

  7. Design, challenge, and promise of stimuli-responsive nanoantibiotics.

    Science.gov (United States)

    Edson, Julius A; Kwon, Young Jik

    2016-01-01

    Over the past few years, there have been calls for novel antimicrobials to combat the rise of drug-resistant bacteria. While some promising new discoveries have met this call, it is not nearly enough. The major problem is that although these new promising antimicrobials serve as a short-term solution, they lack the potential to provide a long-term solution. The conventional method of creating new antibiotics relies heavily on the discovery of an antimicrobial compound from another microbe. This paradigm of development is flawed due to the fact that microbes can easily transfer a resistant mechanism if faced with an environmental pressure. Furthermore, there has been some evidence to indicate that the environment of the microbe can provide a hint as to their virulence. Because of this, the use of materials with antimicrobial properties has been garnering interest. Nanoantibiotics, (nAbts), provide a new way to circumvent the current paradigm of antimicrobial discovery and presents a novel mechanism of attack not found in microbes yet; which may lead to a longer-term solution against drug-resistance formation. This allows for environment-specific activation and efficacy of the nAbts but may also open up and create new design methods for various applications. These nAbts provide promise, but there is still ample work to be done in their development. This review looks at possible ways of improving and optimizing nAbts by making them stimuli-responsive, then consider the challenges ahead, and industrial applications.Graphical abstractA graphic detailing how the current paradigm of antibiotic discovery can be circumvented by the use of nanoantibiotics.

  8. Stimuli-Responsive, Shape-Transforming Nanostructured Particles.

    Science.gov (United States)

    Lee, Junhyuk; Ku, Kang Hee; Kim, Mingoo; Shin, Jae Man; Han, Junghun; Park, Chan Ho; Yi, Gi-Ra; Jang, Se Gyu; Kim, Bumjoon J

    2017-08-01

    Development of particles that change shape in response to external stimuli has been a long-thought goal for producing bioinspired, smart materials. Herein, the temperature-driven transformation of the shape and morphology of polymer particles composed of polystyrene-b-poly(4-vinylpyridine) (PS-b-P4VP) block copolymers (BCPs) and temperature-responsive poly(N-isopropylacrylamide) (PNIPAM) surfactants is reported. PNIPAM acts as a temperature-responsive surfactant with two important roles. First, PNIPAM stabilizes oil-in-water droplets as a P4VP-selective surfactant, creating a nearly neutral interface between the PS and P4VP domains together with cetyltrimethylammonium bromide, a PS-selective surfactant, to form anisotropic PS-b-P4VP particles (i.e., convex lenses and ellipsoids). More importantly, the temperature-directed positioning of PNIPAM depending on its solubility determines the overall particle shape. Ellipsoidal particles are produced above the critical temperature, whereas convex lens-shaped particles are obtained below the critical temperature. Interestingly, given that the temperature at which particle shape change occurs depends solely on the lower critical solution temperature (LCST) of the polymer surfactants, facile tuning of the transition temperature is realized by employing other PNIPAM derivatives with different LCSTs. Furthermore, reversible transformations between different shapes of PS-b-P4VP particles are successfully demonstrated using a solvent-adsorption annealing with chloroform, suggesting great promise of these particles for sensing, smart coating, and drug delivery applications. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Serotonin in the inferior colliculus fluctuates with behavioral state and environmental stimuli.

    Science.gov (United States)

    Hall, Ian C; Rebec, George V; Hurley, Laura M

    2010-04-01

    Neuromodulation by serotonin (5-HT) could link behavioral state and environmental events with sensory processing. Within the auditory system, the presence of 5-HT alters the activity of neurons in the inferior colliculus (IC), but the conditions that influence 5-HT neurotransmission in this region of the brain are unknown. We used in vivo voltammetry to measure extracellular 5-HT in the IC of behaving mice to address this issue. Extracellular 5-HT increased with the recovery from anesthesia, suggesting that the neuromodulation of auditory processing is correlated with the level of behavioral arousal. Awake mice were further exposed to auditory (broadband noise), visual (light) or olfactory (2,5-dihydro-2,4,5-trimethylthiazoline, TMT) stimuli, presented with food or confined in a small arena. Only the auditory stimulus or restricted movement increased the concentration of extracellular 5-HT in the IC. Changes occurred within minutes of stimulus onset, with the auditory stimulus increasing extracellular 5-HT by an average of 5% and restricted movement increasing it by an average of 14%. These findings suggest that the neuromodulation of auditory processing by 5-HT is a dynamic process that is dependent on internal state and behavioral conditions.

  10. The selective processing of emotional visual stimuli while detecting auditory targets: an ERP analysis.

    Science.gov (United States)

    Schupp, Harald T; Stockburger, Jessica; Bublatzky, Florian; Junghöfer, Markus; Weike, Almut I; Hamm, Alfons O

    2008-09-16

    Event-related potential studies revealed an early posterior negativity (EPN) for emotional compared to neutral pictures. Exploring the emotion-attention relationship, a previous study observed that a primary visual discrimination task interfered with the emotional modulation of the EPN component. To specify the locus of interference, the present study assessed the fate of selective visual emotion processing while attention is directed towards the auditory modality. While simply viewing a rapid and continuous stream of pleasant, neutral, and unpleasant pictures in one experimental condition, processing demands of a concurrent auditory target discrimination task were systematically varied in three further experimental conditions. Participants successfully performed the auditory task as revealed by behavioral performance and selected event-related potential components. Replicating previous results, emotional pictures were associated with a larger posterior negativity compared to neutral pictures. Of main interest, increasing demands of the auditory task did not modulate the selective processing of emotional visual stimuli. With regard to the locus of interference, selective emotion processing as indexed by the EPN does not seem to reflect shared processing resources of visual and auditory modality.

  11. Noradrenergic and cholinergic modulation of late ERP responses to deviant stimuli.

    Science.gov (United States)

    Brown, Stephen B R E; van der Wee, Nic J A; van Noorden, Martijn S; Giltay, Erik J; Nieuwenhuis, Sander

    2015-12-01

    Researchers have proposed several hypotheses about the neuromodulator systems involved in generating P3 components of the ERP. To test some of these hypotheses, we conducted a randomized placebo-controlled crossover study in which we investigated how the late positive ERP response to deviant stimuli is modulated by (a) clonidine, an α2 agonist that attenuates baseline noradrenergic activity; and (b) scopolamine, a muscarinic antagonist of acetylcholine receptors. We collected EEG data from 18 healthy volunteers during the performance of an auditory oddball task with several active and passive task conditions. We then used temporospatial principal component analysis (PCA) to decompose the ERP waveforms. The PCA revealed two distinct late positive ERP components: the classic parietal P300 and the frontal novelty P3. Statistical analysis of the temporospatial factor scores indicated that in most conditions the amplitude of the classic P300 was increased by clonidine and scopolamine. In contrast, the amplitude of the novelty P3 was decreased by both drugs. The similar pattern of results for clonidine and scopolamine probably reflects the strong interactions between the noradrenergic and cholinergic systems. The results, in combination with previous pharmacological studies, suggest a critical role for both neuromodulator systems in the generation of the P300 and the novelty P3.

  12. Resistance to Change and Frequency of Response-Dependent Stimuli Uncorrelated with Reinforcement

    Science.gov (United States)

    Podlesnik, Christopher A.; Jimenez-Gomez, Corina; Ward, Ryan D.; Shahan, Timothy A.

    2009-01-01

    Stimuli uncorrelated with reinforcement have been shown to enhance response rates and resistance to disruption; however, the effects of different rates of stimulus presentations have not been assessed. In two experiments, we assessed the effects of adding different rates of response-dependent brief stimuli uncorrelated with primary reinforcement…

  13. Long-latency auditory evoked potentials with verbal and nonverbal stimuli,

    Directory of Open Access Journals (Sweden)

    Sheila Jacques Oppitz

    2015-12-01

    Full Text Available ABSTRACT INTRODUCTION: Long-latency auditory evoked potentials represent the cortical activity related to attention, memory, and auditory discrimination skills. Acoustic signal processing occurs differently between verbal and nonverbal stimuli, influencing the latency and amplitude patterns. OBJECTIVE: To describe the latencies of the cortical potentials P1, N1, P2, N2, and P3, as well as P3 amplitude, with different speech stimuli and tone bursts, and to classify them in the presence and absence of these data. METHODS: A total of 30 subjects with normal hearing were assessed, aged 18-32 years old, matched by gender. Nonverbal stimuli were used (tone burst; 1000 Hz - frequent and 4000 Hz - rare; and verbal (/ba/ - frequent; /ga/, /da/, and /di/ - rare. RESULTS: Considering the component N2 for tone burst, the lowest latency found was 217.45 ms for the BA/DI stimulus; the highest latency found was 256.5 ms. For the P3 component, the shortest latency with tone burst stimuli was 298.7 with BA/GA stimuli, the highest, was 340 ms. For the P3 amplitude, there was no statistically significant difference among the different stimuli. For latencies of components P1, N1, P2, N2, P3, there were no statistical differences among them, regardless of the stimuli used. CONCLUSION: There was a difference in the latency of potentials N2 and P3 among the stimuli employed but no difference was observed for the P3 amplitude.

  14. Natural stimuli improve auditory BCIs with respect to ergonomics and performance

    Science.gov (United States)

    Höhne, Johannes; Krenzlin, Konrad; Dähne, Sven; Tangermann, Michael