Effects of age, gender, and stimulus presentation period on visual short-term memory.
Kunimi, Mitsunobu
2016-01-01
This study focused on age-related changes in visual short-term memory using visual stimuli that did not allow verbal encoding. Experiment 1 examined the effects of age and the length of the stimulus presentation period on visual short-term memory function. Experiment 2 examined the effects of age, gender, and the length of the stimulus presentation period on visual short-term memory function. The worst memory performance and the largest performance difference between the age groups were observed in the shortest stimulus presentation period conditions. The performance difference between the age groups became smaller as the stimulus presentation period became longer; however, it did not completely disappear. Although gender did not have a significant effect on d' regardless of the presentation period in the young group, a significant gender-based difference was observed for stimulus presentation periods of 500 ms and 1,000 ms in the older group. This study indicates that the decline in visual short-term memory observed in the older group is due to the interaction of several factors.
Effect of occlusal (mechanical) stimulus on bone remodelling in rat mandibular condyle.
Gazit, D; Ehrlich, J; Kohen, Y; Bab, I
1987-09-01
Mechanical load influences the remodelling of skeletal tissues. In the mandibular condyle, occlusal alterations and the consequent mechanical stimulus induce changes in chondrocytes and cartilage mineralization. In the present study we quantified in the mandibular condyle the effect of occlusal interference on remodelling of the subchondral bone. Computerized histomorphometry after 5-21-day exposure to the influence of a unilateral occlusal splint revealed an increased rate of trabecular remodelling, consisting of enhancement in osteoblast and osteoclast numbers and activities. The bone formation parameters reached their high values on Days 5 or 9 and remained stable thereafter. Bone resorption showed a gradual increase throughout the experimental period. These results further characterize the temporomandibular joint reaction to occlusal alterations. It is suggested that the present increase in bone turnover together with the known enhancement in chondrogenesis are part of a process of functional adaptation in response to mechanical stimulus.
Dendrites Enable a Robust Mechanism for Neuronal Stimulus Selectivity.
Cazé, Romain D; Jarvis, Sarah; Foust, Amanda J; Schultz, Simon R
2017-09-01
Hearing, vision, touch: underlying all of these senses is stimulus selectivity, a robust information processing operation in which cortical neurons respond more to some stimuli than to others. Previous models assume that these neurons receive the highest weighted input from an ensemble encoding the preferred stimulus, but dendrites enable other possibilities. Nonlinear dendritic processing can produce stimulus selectivity based on the spatial distribution of synapses, even if the total preferred stimulus weight does not exceed that of nonpreferred stimuli. Using a multi-subunit nonlinear model, we demonstrate that stimulus selectivity can arise from the spatial distribution of synapses. We propose this as a general mechanism for information processing by neurons possessing dendritic trees. Moreover, we show that this implementation of stimulus selectivity increases the neuron's robustness to synaptic and dendritic failure. Importantly, our model can maintain stimulus selectivity for a larger range of loss of synapses or dendrites than an equivalent linear model. We then use a layer 2/3 biophysical neuron model to show that our implementation is consistent with two recent experimental observations: (1) one can observe a mixture of selectivities in dendrites that can differ from the somatic selectivity, and (2) hyperpolarization can broaden somatic tuning without affecting dendritic tuning. Our model predicts that an initially nonselective neuron can become selective when depolarized. In addition to motivating new experiments, the model's increased robustness to synapses and dendrites loss provides a starting point for fault-resistant neuromorphic chip development.
Does air gas aesthesiometry generate a true mechanical stimulus for corneal sensitivity measurement?
Nosch, Daniela S; Pult, Heiko; Albon, Julie; Purslow, Christine; Murphy, Paul J
2018-03-01
Belmonte Ocular Pain Meter (OPM) air jet aesthesiometry overcomes some of the limitations of the Cochet-Bonnet aesthesiometer. However, for true mechanical corneal sensitivity measurement, the airflow stimulus temperature of the aesthesiometer must equal ocular surface temperature (OST), to avoid additional response from temperature-sensitive nerves. The aim of this study was to determine: (A) the stimulus temperature inducing no or least change in OST; and (B) to evaluate if OST remains unchanged with different stimulus durations and airflow rates. A total of 14 subjects (mean age 25.14 ± 2.18 years; seven women) participated in this clinical cohort study: (A) OST was recorded using an infrared camera (FLIR A310) during the presentation of airflow stimuli, at five temperatures, ambient temperature (AT) +5°C, +10°C, +15°C, +20°C and +30°C, using the OPM aesthesiometer (duration three seconds; over a four millimetre distance; airflow rate 60 ml/min); and (B) OST measurements were repeated with two stimulus temperatures (AT +10°C and +15°C) while varying stimulus durations (three seconds and five seconds) and airflow rates (30, 60, 80 and 100 ml/min). Inclusion criteria were age measures (analysis of variance) and appropriate post-hoc t-tests were applied. (A) Stimulus temperatures of AT +10°C and +15°C induced the least changes in OST (-0.20 ± 0.13°C and 0.08 ± 0.05°C). (B) OST changes were statistically significant with both stimulus temperatures and increased with increasing airflow rates (p air stimulus of the Belmonte OPM because its air jet stimulus with mechanical setting is likely to have a thermal component. Appropriate stimulus selection for an air jet aesthesiometer must incorporate stimulus temperature control that can vary with stimulus duration and airflow rate. © 2017 Optometry Australia.
International Nuclear Information System (INIS)
Zhang Xu; Liu Xiaoli; Sun Jialun; He Shuojie; Lee, Imshik; Pak, Hyuk Kyu
2008-01-01
Osteoblast, playing a key role in the pathophysiology of osteoporosis, is one of the mechanical stress sensitive cells. The effects of mechanical load-induced changes of mechanical properties in osteoblast cells were studied at real-time. Osteoblasts obtained from young Wister rats were exposed to mechanical loads in different frequencies and resting intervals generated by atomic force microscopy (AFM) probe tip and simultaneously measured the changes of the mechanical properties by AFM. The enhancement of the mechanical properties was observed and quantified by the increment of the apparent Young's modulus, E * . The observed mechanical property depended on the frequency of applied tapping loads. For the resting interval is 50 s, the mechanical load-induced enhancement of E * -values disappears. It seems that the enhanced mechanical property was recover able under no additional mechanical stimulus
Hsu, Shen-Mou; Yang, Yu-Fang
2018-04-01
An important issue facing the empirical study of consciousness concerns how the contents of incoming stimuli gain access to conscious processing. According to classic theories, facial stimuli are processed in a hierarchical manner. However, it remains unclear how the brain determines which level of stimulus content is consciously accessible when facing an incoming facial stimulus. Accordingly, with a magnetoencephalography technique, this study aims to investigate the temporal dynamics of the neural mechanism mediating which level of stimulus content is consciously accessible. Participants were instructed to view masked target faces at threshold so that, according to behavioral responses, their perceptual awareness alternated from consciously accessing facial identity in some trials to being able to consciously access facial configuration features but not facial identity in other trials. Conscious access at these two levels of facial contents were associated with a series of differential neural events. Before target presentation, different patterns of phase angle adjustment were observed between the two types of conscious access. This effect was followed by stronger phase clustering for awareness of facial identity immediately during stimulus presentation. After target onset, conscious access to facial identity, as opposed to facial configural features, was able to elicit more robust late positivity. In conclusion, we suggest that the stages of neural events, ranging from prestimulus to stimulus-related activities, may operate in combination to determine which level of stimulus contents is consciously accessed. Conscious access may thus be better construed as comprising various forms that depend on the level of stimulus contents accessed. NEW & NOTEWORTHY The present study investigates how the brain determines which level of stimulus contents is consciously accessible when facing an incoming facial stimulus. Using magnetoencephalography, we show that prestimulus
Spatio-temporal brain dynamics in a combined stimulus-stimulus and stimulus-response conflict task.
Frühholz, Sascha; Godde, Ben; Finke, Mareike; Herrmann, Manfred
2011-01-01
It is yet not well known whether different types of conflicts share common or rely on distinct brain mechanisms of conflict processing. We used a combined Flanker (stimulus-stimulus; S-S) and Simon (stimulus-response; S-R) conflict paradigm both in an fMRI and an EEG study. S-S conflicts induced stronger behavioral interference effects compared to S-R conflicts and the latter decayed with increasing response latencies. Besides some similar medial frontal activity across all conflict trials, which was, however, not statically consistent across trials, we especially found distinct activations depending on the type of conflict. S-S conflicts activated the anterior cingulate cortex and modulated the N2 and early P3 component with underlying source activity in inferior frontal cortex. S-R conflicts produced distinct activations in the posterior cingulate cortex and modulated the late P3b component with underlying source activity in superior parietal cortex. Double conflict trials containing both S-S and S-R conflicts revealed, first, distinct anterior frontal activity representing a meta-processing unit and, second, a sequential modulation of the N2 and the P3b component. The N2 modulation during double conflict trials was accompanied by increased source activity in the medial frontal gyrus (MeFG). In summary, S-S and S-R conflict processing mostly rely on distinct mechanisms of conflict processing and these conflicts differentially modulate the temporal stages of stimulus processing. Copyright © 2010 Elsevier Inc. All rights reserved.
Mechanisms underlying effects of approach-avoidance training on stimulus evaluation.
Van Dessel, Pieter; Eder, Andreas B; Hughes, Sean
2018-04-12
Over the past decade an increasing number of studies across a range of domains have shown that the repeated performance of approach and avoidance (AA) actions in response to a stimulus leads to changes in the evaluation of that stimulus. The dominant (motivational-systems) account in this area claims that these effects are caused by a rewiring of mental associations between stimulus representations and AA systems that evolved to regulate distances to positive and negative stimuli. In contrast, two recently forwarded alternative accounts postulate that AA effects are caused by inferences about the valence of actions and stimuli (inferential account) or a transfer of valenced action codes to stimulus representations (common-coding account). Across four experiments we set out to test these three competing accounts against each other. Experiments 1-3 illustrate that changes in stimulus evaluations can occur when people perform valenced actions that bear no relation to a distance regulation, such as moving a manikin upward or downward. The observed evaluative effects were dependent on the evaluative implication of the instructed movement goal rather than whether the action implied a movement toward or away from the stimuli. These results could not be explained with a rewiring of associations to motivational systems. Experiment 4 showed that changes in stimulus evaluations occurred after participants passively observed approach-avoidance movements, supporting an explanation in terms of cognitive inferences. (PsycINFO Database Record (c) 2018 APA, all rights reserved).
Effects of stimulus-driven synchronization on sensory perception
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Holden Jameson K
2007-12-01
Full Text Available Abstract Background A subject's ability to differentiate the loci of two points on the skin depends on the stimulus-evoked pericolumnar lateral inhibitory interactions which increase the spatial contrast between regions of SI cortex that are activated by stimulus-evoked afferent drive. Nevertheless, there is very little known about the impact that neuronal interactions – such as those evoked by mechanical skin stimuli that project to and coordinate synchronized activity in adjacent and/or near-adjacent cortical columns – could have on sensory information processing. Methods The temporal order judgment (TOJ and temporal discriminative threshold (TDT of 20 healthy adult subjects were assessed both in the absence and presence of concurrent conditions of tactile stimulation. These measures were obtained across a number of paired sites – two unilateral and one bilateral – and several conditions of adapting stimuli were delivered both prior to and concurrently with the TOJ and TDT tasks. The pairs of conditioning stimuli were synchronized and periodic, synchronized and non-periodic, or asynchronous and non-periodic. Results In the absence of any additional stimuli, TOJ and TDT results obtained from the study were comparable across a number of pairs of stimulus sites – unilateral as well as bilateral. In the presence of a 25 Hz conditioning sinusoidal stimulus which was delivered both before, concurrently and after the TOJ task, there was a significant change in the TOJ measured when the two stimuli were located unilaterally on digits 2 and 3. However, in the presence of the same 25 Hz conditioning stimulus, the TOJ obtained when the two stimuli were delivered bilaterally was not impacted. TDT measures were not impacted to the same degree by the concurrent stimuli that were delivered to the unilateral or bilateral stimulus sites. This led to the speculation that the impact that the conditioning stimuli – which were sinusoidal, periodic and
Stimulus-dependent modulation of spontaneous low-frequency oscillations in the rat visual cortex.
Huang, Liangming; Liu, Yadong; Gui, Jianjun; Li, Ming; Hu, Dewen
2014-08-06
Research on spontaneous low-frequency oscillations is important to reveal underlying regulatory mechanisms in the brain. The mechanism for the stimulus modulation of low-frequency oscillations is not known. Here, we used the intrinsic optical imaging technique to examine stimulus-modulated low-frequency oscillation signals in the rat visual cortex. The stimulation was presented monocularly as a flashing light with different frequencies and intensities. The phases of low-frequency oscillations in different regions tended to be synchronized and the rhythms typically accelerated within a 30-s period after stimulation. These phenomena were confined to visual stimuli with specific flashing frequencies (12.5-17.5 Hz) and intensities (5-10 mA). The acceleration and synchronization induced by the flashing frequency were more marked than those induced by the intensity. These results show that spontaneous low-frequency oscillations can be modulated by parameter-dependent flashing lights and indicate the potential utility of the visual stimulus paradigm in exploring the origin and function of low-frequency oscillations.
Temporal and spectral profiles of stimulus-stimulus and stimulus-response conflict processing.
Wang, Kai; Li, Qi; Zheng, Ya; Wang, Hongbin; Liu, Xun
2014-04-01
The ability to detect and resolve conflict is an essential function of cognitive control. Laboratory studies often use stimulus-response-compatibility (SRC) tasks to examine conflict processing in order to elucidate the mechanism and modular organization of cognitive control. Inspired by two influential theories regarding cognitive control, the conflict monitoring theory (Botvinick, Braver, Barch, Carter, & Cohen, 2001) and dimensional overlap taxonomy (Kornblum, Hasbroucq, & Osman, 1990), we explored the temporal and spectral similarities and differences between processing of stimulus-stimulus (S-S) and stimulus-response (S-R) conflicts with event related potential (ERP) and time-frequency measures. We predicted that processing of S-S conflict starts earlier than that of S-R conflict and that the two types of conflict may involve different frequency bands. Participants were asked to perform two parallel SRC tasks, both combining the Stroop task (involving S-S conflict) and Simon task (involving S-R conflict). ERP results showed pronounced SRC effects (incongruent vs. congruent) on N2 and P3 components for both S-S and S-R conflicts. In both tasks, SRC effects of S-S conflict took place earlier than those of S-R conflict. Time-frequency analysis revealed that both types of SRC effects modulated theta and alpha bands, while S-R conflict effects additionally modulated power in the beta band. These results indicated that although S-S and S-R conflict processing shared considerable ERP and time-frequency properties, they differed in temporal and spectral dynamics. We suggest that the modular organization of cognitive control should take both commonality and distinction of S-S and S-R conflict processing into consideration. Copyright © 2013 Elsevier Inc. All rights reserved.
Suboptimal Choice in Pigeons: Stimulus Value Predicts Choice over Frequencies.
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Aaron P Smith
Full Text Available Pigeons have shown suboptimal gambling-like behavior when preferring a stimulus that infrequently signals reliable reinforcement over alternatives that provide greater reinforcement overall. As a mechanism for this behavior, recent research proposed that the stimulus value of alternatives with more reliable signals for reinforcement will be preferred relatively independently of their frequencies. The present study tested this hypothesis using a simplified design of a Discriminative alternative that, 50% of the time, led to either a signal for 100% reinforcement or a blackout period indicative of 0% reinforcement against a Nondiscriminative alternative that always led to a signal that predicted 50% reinforcement. Pigeons showed a strong preference for the Discriminative alternative that remained despite reducing the frequency of the signal for reinforcement in subsequent phases to 25% and then 12.5%. In Experiment 2, using the original design of Experiment 1, the stimulus following choice of the Nondiscriminative alternative was increased to 75% and then to 100%. Results showed that preference for the Discriminative alternative decreased only when the signals for reinforcement for the two alternatives predicted the same probability of reinforcement. The ability of several models to predict this behavior are discussed, but the terminal link stimulus value offers the most parsimonious account of this suboptimal behavior.
Gabard-Durnam, Laurel Joy; Gee, Dylan Grace; Goff, Bonnie; Flannery, Jessica; Telzer, Eva; Humphreys, Kathryn Leigh; Lumian, Daniel Stephen; Fareri, Dominic Stephen; Caldera, Christina; Tottenham, Nim
2016-04-27
Although the functional architecture of the brain is indexed by resting-state connectivity networks, little is currently known about the mechanisms through which these networks assemble into stable mature patterns. The current study posits and tests the long-term phasic molding hypothesis that resting-state networks are gradually shaped by recurring stimulus-elicited connectivity across development by examining how both stimulus-elicited and resting-state functional connections of the human brain emerge over development at the systems level. Using a sequential design following 4- to 18-year-olds over a 2 year period, we examined the predictive associations between stimulus-elicited and resting-state connectivity in amygdala-cortical circuitry as an exemplar case (given this network's protracted development across these ages). Age-related changes in amygdala functional connectivity converged on the same regions of medial prefrontal cortex (mPFC) and inferior frontal gyrus when elicited by emotional stimuli and when measured at rest. Consistent with the long-term phasic molding hypothesis, prospective analyses for both connections showed that the magnitude of an individual's stimulus-elicited connectivity unidirectionally predicted resting-state functional connectivity 2 years later. For the amygdala-mPFC connection, only stimulus-elicited connectivity during childhood and the transition to adolescence shaped future resting-state connectivity, consistent with a sensitive period ending with adolescence for the amygdala-mPFC circuit. Together, these findings suggest that resting-state functional architecture may arise from phasic patterns of functional connectivity elicited by environmental stimuli over the course of development on the order of years. A fundamental issue in understanding the ontogeny of brain function is how resting-state (intrinsic) functional networks emerge and relate to stimulus-elicited functional connectivity. Here, we posit and test the long
Anticipation increases tactile stimulus processing in the ipsilateral primary somatosensory cortex.
van Ede, Freek; de Lange, Floris P; Maris, Eric
2014-10-01
Stimulus anticipation improves perception. To account for this improvement, we investigated how stimulus processing is altered by anticipation. In contrast to a large body of previous work, we employed a demanding perceptual task and investigated sensory responses that occur beyond early evoked activity in contralateral primary sensory areas: Stimulus-induced modulations of neural oscillations. For this, we recorded magnetoencephalography in 19 humans while they performed a cued tactile identification task involving the identification of either a proximal or a distal stimulation on the fingertips. We varied the cue-target interval between 0 and 1000 ms such that tactile targets occurred at various degrees of anticipation. This allowed us to investigate the influence of anticipation on stimulus processing in a parametric fashion. We observed that anticipation increases the stimulus-induced response (suppression of beta-band oscillations) originating from the ipsilateral primary somatosensory cortex. This occurs in the period in which the tactile memory trace is analyzed and is correlated with the anticipation-induced improvement in tactile perception. We propose that this ipsilateral response indicates distributed processing across bilateral primary sensory cortices, of which the extent increases with anticipation. This constitutes a new and potentially important mechanism contributing to perception and its improvement following anticipation. © The Author 2013. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.
Meier, Matt E.; Kane, Michael J.
2015-01-01
Three experiments examined the relation between working memory capacity (WMC) and 2 different forms of cognitive conflict: stimulus-stimulus (S-S) and stimulus-response (S-R) interference. Our goal was to test whether WMC's relation to conflict-task performance is mediated by stimulus-identification processes (captured by S-S conflict),…
Spatiotemporal Dynamics of Cortical Representations during and after Stimulus Presentation
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Marieke Esther van de Nieuwenhuijzen
2016-05-01
Full Text Available Visual perception is a spatiotemporally complex process. In this study, we investigated cortical dynamics during and after stimulus presentation. We observed that visual category information related to the difference between faces and objects became apparent in the occipital lobe after 63 ms. Within the next 110 ms, activation spread out to include the temporal lobe before returning to residing mainly in the occipital lobe again. After stimulus offset, a peak in information was observed, comparable to the peak after stimulus onset. Moreover, similar processes, albeit not identical, seemed to underlie both peaks. Information about the categorical identity of the stimulus remained present until 677 ms after stimulus offset, during which period the stimulus had to be retained in working memory. Activation patterns initially resembled those observed during stimulus presentation. After about 200 ms, however, this representation changed and class-specific activity became more equally distributed over the four lobes. These results show that, although there are common processes underlying stimulus representation both during and after stimulus presentation, these representations change depending on the specific stage of perception and maintenance.
Lim, Edwin Choon Wyn; Sterling, Michele; Vicenzino, Bill
2017-10-01
The impaired attenuation of pain by the application of a noxious conditioning stimulus at a segmentally distinct site, known as conditioned pain modulation (CPM), has been implicated in clinical pain states. Chronic lateral epicondylalgia (LE), which is characterized by lower pressure pain thresholds (PPTs) at sites remote to the affected elbow and spinal cord hyperexcitability, is a clinical pain state that might plausibly involve less efficacious CPM. This study aimed to determine whether LE exhibits a less efficacious CPM compared with that in pain-free controls. Results: Twenty participants with LE, aged 50.7 years (SD=7.05) and who had their condition for 10.2 months (range: 2 to 80 mo), were matched by age and sex to 22 pain-free participants. All participants indicated their PPT over the lateral epicondyle(s) before and during a conditioning noxious heat stimulus that was applied over the calf. A CPM score was calculated as the difference between the PPT before and during the heat pain-conditioning stimulus expressed as a percentage of PPT before the heat pain-conditioning stimulus. The condition (LE vs. control) by side (affected vs. unaffected) analysis of variance revealed a significant condition effect (P=0.001), but not side effect (P=0.192) or side-by-condition interaction effect (P=0.951). Follow-up tests for the effect of condition revealed a mean deficit in CPM of -24.5% (95% confidence interval, -38.0 to -11.0) in LE compared with that in pain-free participants. The results that suggest an impaired ability to modulate pain might be associated with the previously observed spinal cord hyperexcitability and the mechanical hyperalgesia that characterizes LE.
Voort van der Kleij, van der Gwendid T.
2007-01-01
This thesis investigates the mechanisms of stimulus-driven visual attention (global saliency), the mechanisms of top-down visual attention, and the interaction between these mechanisms, in visual search. Following the outline of an existing model of top-down visual attention, namely the Closed-Loop
Stimulus size dependence of hue changes induced by chromatic surrounds.
Kellner, Christian Johannes; Wachtler, Thomas
2016-03-01
A chromatic surround induces a change in the perceived hue of a stimulus. This shift in hue depends on the chromatic difference between the stimulus and the surround. We investigated how chromatic induction varies with stimulus size and whether the size dependence depends on the surround hue. Subjects performed asymmetric matching of color stimuli with different sizes in surrounds of different chromaticities. Generally, induced hue shifts decreased with increasing stimulus size. This decrease was quantitatively different for different surround hues. However, when size effects were normalized to an overall induction strength, the chromatic specificity was largely reduced. The separability of inducer chromaticity and stimulus size suggests that these effects are mediated by different neural mechanisms.
Marshall, Tom R; den Boer, Sebastiaan; Cools, Roshan; Jensen, Ole; Fallon, Sean James; Zumer, Johanna M
2018-01-01
Selective attention is reflected neurally in changes in the power of posterior neural oscillations in the alpha (8-12 Hz) and gamma (40-100 Hz) bands. Although a neural mechanism that allows relevant information to be selectively processed has its advantages, it may lead to lucrative or dangerous information going unnoticed. Neural systems are also in place for processing rewarding and punishing information. Here, we examine the interaction between selective attention (left vs. right) and stimulus's learned value associations (neutral, punished, or rewarded) and how they compete for control of posterior neural oscillations. We found that both attention and stimulus-value associations influenced neural oscillations. Whereas selective attention had comparable effects on alpha and gamma oscillations, value associations had dissociable effects on these neural markers of attention. Salient targets (associated with positive and negative outcomes) hijacked changes in alpha power-increasing hemispheric alpha lateralization when salient targets were attended, decreasing it when they were being ignored. In contrast, hemispheric gamma-band lateralization was specifically abolished by negative distractors. Source analysis indicated occipital generators of both attentional and value effects. Thus, posterior cortical oscillations support both the ability to selectively attend while at the same time retaining the ability to remain sensitive to valuable features in the environment. Moreover, the versatility of our attentional system to respond separately to salient from merely positively valued stimuli appears to be carried out by separate neural processes reflected in different frequency bands.
Laub, Ruth; Frings, Christian; Moeller, Birte
2018-04-23
In selection tasks, target and distractor features can be encoded together with the response into the same short-lived memory trace, or event file (see Hommel, 2004), leading to bindings between stimulus and response features. The repetition of a stored target or distractor feature can lead to the retrieval of the entire episode, including the response-so-called "binding effects." Binding effects due to distractor repetition are stronger for grouped than for nongrouped target and distractor stimulus configurations. Modulation of either of two mechanisms that lead to the observed binding effects might be responsible here: Grouping may influence either stimulus-response integration or stimulus-response retrieval. In the present study we investigated the influences of grouping on both mechanisms independently. In two experiments, target and distractor letters were grouped (or nongrouped) via color (dis)similarity separately during integration and retrieval. Grouping by color similarity affected integration and retrieval mechanisms independently and in different ways. Color dissimilarity enhanced distractor-based retrieval, whereas color similarity enhanced distractor integration. We concluded that stimulus grouping is relevant for binding effects, but that the mechanisms that contribute to binding effects should be carefully separated.
Nanoscale theranostics for physical stimulus-responsive cancer therapies.
Chen, Qian; Ke, Hengte; Dai, Zhifei; Liu, Zhuang
2015-12-01
Physical stimulus-responsive therapies often employing multifunctional theranostic agents responsive to external physical stimuli such as light, magnetic field, ultra-sound, radiofrequency, X-ray, etc., have been widely explored as novel cancer therapy strategies, showing encouraging results in many pre-clinical animal experiments. Unlike conventional cancer chemotherapy which often accompanies with severe toxic side effects, physical stimulus-responsive agents usually are non-toxic by themselves and would destruct cancer cells only under specific external stimuli, and thus could offer greatly reduced toxicity and enhanced treatment specificity. In addition, physical stimulus-responsive therapies can also be combined with other traditional therapeutics to achieve synergistic anti-tumor effects via a variety of mechanisms. In this review, we will summarize the latest progress in the development of physical stimulus-responsive therapies, and discuss the important roles of nanoscale theranostic agents involved in those non-conventional therapeutic strategies. Copyright © 2015 Elsevier Ltd. All rights reserved.
Enhanced stimulus-induced gamma activity in humans during propofol-induced sedation.
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Neeraj Saxena
Full Text Available Stimulus-induced gamma oscillations in the 30-80 Hz range have been implicated in a wide number of functions including visual processing, memory and attention. While occipital gamma-band oscillations can be pharmacologically modified in animal preparations, pharmacological modulation of stimulus-induced visual gamma oscillations has yet to be demonstrated in non-invasive human recordings. Here, in fifteen healthy humans volunteers, we probed the effects of the GABAA agonist and sedative propofol on stimulus-related gamma activity recorded with magnetoencephalography, using a simple visual grating stimulus designed to elicit gamma oscillations in the primary visual cortex. During propofol sedation as compared to the normal awake state, a significant 60% increase in stimulus-induced gamma amplitude was seen together with a 94% enhancement of stimulus-induced alpha suppression and a simultaneous reduction in the amplitude of the pattern-onset evoked response. These data demonstrate, that propofol-induced sedation is accompanied by increased stimulus-induced gamma activity providing a potential window into mechanisms of gamma-oscillation generation in humans.
Brain bases for auditory stimulus-driven figure-ground segregation.
Teki, Sundeep; Chait, Maria; Kumar, Sukhbinder; von Kriegstein, Katharina; Griffiths, Timothy D
2011-01-05
Auditory figure-ground segregation, listeners' ability to selectively hear out a sound of interest from a background of competing sounds, is a fundamental aspect of scene analysis. In contrast to the disordered acoustic environment we experience during everyday listening, most studies of auditory segregation have used relatively simple, temporally regular signals. We developed a new figure-ground stimulus that incorporates stochastic variation of the figure and background that captures the rich spectrotemporal complexity of natural acoustic scenes. Figure and background signals overlap in spectrotemporal space, but vary in the statistics of fluctuation, such that the only way to extract the figure is by integrating the patterns over time and frequency. Our behavioral results demonstrate that human listeners are remarkably sensitive to the appearance of such figures. In a functional magnetic resonance imaging experiment, aimed at investigating preattentive, stimulus-driven, auditory segregation mechanisms, naive subjects listened to these stimuli while performing an irrelevant task. Results demonstrate significant activations in the intraparietal sulcus (IPS) and the superior temporal sulcus related to bottom-up, stimulus-driven figure-ground decomposition. We did not observe any significant activation in the primary auditory cortex. Our results support a role for automatic, bottom-up mechanisms in the IPS in mediating stimulus-driven, auditory figure-ground segregation, which is consistent with accumulating evidence implicating the IPS in structuring sensory input and perceptual organization.
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Tao Wang
2013-01-01
Full Text Available To obtain reliable transient auditory evoked potentials (AEPs from EEGs recorded using high stimulus rate (HSR paradigm, it is critical to design the stimulus sequences of appropriate frequency properties. Traditionally, the individual stimulus events in a stimulus sequence occur only at discrete time points dependent on the sampling frequency of the recording system and the duration of stimulus sequence. This dependency likely causes the implementation of suboptimal stimulus sequences, sacrificing the reliability of resulting AEPs. In this paper, we explicate the use of continuous-time stimulus sequence for HSR paradigm, which is independent of the discrete electroencephalogram (EEG recording system. We employ simulation studies to examine the applicability of the continuous-time stimulus sequences and the impacts of sampling frequency on AEPs in traditional studies using discrete-time design. Results from these studies show that the continuous-time sequences can offer better frequency properties and improve the reliability of recovered AEPs. Furthermore, we find that the errors in the recovered AEPs depend critically on the sampling frequencies of experimental systems, and their relationship can be fitted using a reciprocal function. As such, our study contributes to the literature by demonstrating the applicability and advantages of continuous-time stimulus sequences for HSR paradigm and by revealing the relationship between the reliability of AEPs and sampling frequencies of the experimental systems when discrete-time stimulus sequences are used in traditional manner for the HSR paradigm.
Highly Reconfigurable Beamformer Stimulus Generator
Vaviļina, E.; Gaigals, G.
2018-02-01
The present paper proposes a highly reconfigurable beamformer stimulus generator of radar antenna array, which includes three main blocks: settings of antenna array, settings of objects (signal sources) and a beamforming simulator. Following from the configuration of antenna array and object settings, different stimulus can be generated as the input signal for a beamformer. This stimulus generator is developed under a greater concept with two utterly independent paths where one is the stimulus generator and the other is the hardware beamformer. Both paths can be complemented in final and in intermediate steps as well to check and improve system performance. This way the technology development process is promoted by making each of the future hardware steps more substantive. Stimulus generator configuration capabilities and test results are presented proving the application of the stimulus generator for FPGA based beamforming unit development and tuning as an alternative to an actual antenna system.
Meier, Matt E.; Kane, Michael J.
2015-01-01
Three experiments examined the relation between working memory capacity (WMC) and two different forms of cognitive conflict: stimulus-stimulus (S-S) and stimulus-response (SR) interference. Our goal was to test whether WMC’s relation to conflict-task performance is mediated by stimulus-identification processes (captured by S-S conflict), response-selection processes (captured by S-R conflict), or both. In Experiment 1, subjects completed a single task presenting both S-S and S-R conflict trials, plus trials that combined the two conflict types. We limited ostensible goal-maintenance contributions to performance by requiring the same goal for all trial types and by presenting frequent conflict trials that reinforced the goal. WMC predicted resolution of S-S conflict as expected: Higher-WMC subjects showed reduced response time interference. Although WMC also predicted S-R interference, here, higher-WMC subjects showed increased error interference. Experiment 2A replicated these results in a version of the conflict task without combined S-S/S-R trials. Experiment 2B increased the proportion of congruent (non-conflict) trials to promote reliance on goal-maintenance processes. Here, higher-WMC subjects resolved both S-S and S-R conflict more successfully than did lower-WMC subjects. The results were consistent with Kane and Engle’s (2003) two-factor theory of cognitive control, according to which WMC predicts executive-task performance through goal-maintenance and conflict-resolution processes. However, the present results add specificity to the account by suggesting that higher-WMC subjects better resolve cognitive conflict because they more efficiently select relevant stimulus features against irrelevant, distracting ones. PMID:26120774
Highly Reconfigurable Beamformer Stimulus Generator
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Vaviļina E.
2018-02-01
Full Text Available The present paper proposes a highly reconfigurable beamformer stimulus generator of radar antenna array, which includes three main blocks: settings of antenna array, settings of objects (signal sources and a beamforming simulator. Following from the configuration of antenna array and object settings, different stimulus can be generated as the input signal for a beamformer. This stimulus generator is developed under a greater concept with two utterly independent paths where one is the stimulus generator and the other is the hardware beamformer. Both paths can be complemented in final and in intermediate steps as well to check and improve system performance. This way the technology development process is promoted by making each of the future hardware steps more substantive. Stimulus generator configuration capabilities and test results are presented proving the application of the stimulus generator for FPGA based beamforming unit development and tuning as an alternative to an actual antenna system.
Davison, Michael; Baum, William M.
2010-01-01
Four pigeons were trained in a procedure in which concurrent-schedule food ratios changed unpredictably across seven unsignaled components after 10 food deliveries. Additional green-key stimulus presentations also occurred on the two alternatives, sometimes in the same ratio as the component food ratio, and sometimes in the inverse ratio. In eight…
Imitation in Infancy: The Wealth of the Stimulus
Ray, Elizabeth; Heyes, Cecilia
2011-01-01
Imitation requires the imitator to solve the correspondence problem--to translate visual information from modelled action into matching motor output. It has been widely accepted for some 30 years that the correspondence problem is solved by a specialized, innate cognitive mechanism. This is the conclusion of a poverty of the stimulus argument,…
Glennon, R A; Young, R; Herndon, J L
1993-08-01
Employing rats trained to discriminate 5 mg/kg of the benzomorphan opioid (+)N-allylnormetazocine [(+)NANM] from vehicle, tests of stimulus generalization and antagonism were conducted to determine the influence of several potential sigma-receptor ligands. It has been previously suggested that the (+)NANM stimulus may involve concurrent action at sigma- and phencyclidine (PCP) receptors. Although the low-affinity sigma-antagonist rimcazole was without stimulus-attenuating effect, three novel sigma-ligands--(-)PPAP, CNS 3018, and CNS 3093 (ID50 doses = 3.2, 6.7, and 4.5 mg/kg, respectively)--antagonized the (+)NANM stimulus in a dose-related fashion. The nonselective serotonergic agent 1-(3-trifluoromethyl)phenylpiperazine (TFMPP) produced partial generalization in (+)NANM-trained animals whereas buspirone, a 5-hydroxytryptamine1A (5-HT1A) agonist, attenuated (to 27% drug-appropriate responding) the (+)NANM stimulus. Because the prototypic 5-HT1A agonist 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) failed to attenuate the (+)NANM stimulus at pharmacologically relevant doses, it seems unlikely that the (+)NANM stimulus involves a 5-HT1A mechanism. TFMPP and buspirone display modest affinity for sigma-receptors and this may account for the present findings with these agents. The present results neither establish a role for sigma involvement in the stimulus properties of (+)NANM nor eliminate a role for PCP receptors. They do, however, demonstrate that sigma-ligands with little to no affinity for PCP receptors are capable of antagonizing the (+)NANM stimulus.
Intrinsic periodicity: the forgotten lesson of quantum mechanics
International Nuclear Information System (INIS)
Dolce, Donatello
2013-01-01
Wave-particle duality, together with the concept of elementary particles, was introduced by de Broglie in terms of intrinsically periodic phenomena. However, after nearly 90 years, the physical origin of such undulatory mechanics remains unrevealed. We propose a natural realization of the de Broglie periodic phenomenon in terms of harmonic vibrational modes associated to space-time periodicities. In this way we find that, similarly to a vibrating string or a particle in a box, the intrinsic recurrence imposed as a constraint to elementary particles represents a fully consistent quantization condition. The resulting cyclic dynamics formally match ordinary relativistic Quantum Mechanics in both the canonical and Feynman formulations. Interactions are introduced in a geometrodynamical way, similarly to general relativity, by simply considering that variations of kinematical state can be equivalently described in terms of modulations of space-time recurrences, as known from undulatory mechanics. We present this novel quantization prescription from an historical prospective.
Electrophysiological Correlates of Changes in Reaction Time Based on Stimulus Intensity
Lakhani, Bimal; Vette, Albert H.; Mansfield, Avril; Miyasike-daSilva, Veronica; McIlroy, William E.
2012-01-01
Background Although reaction time is commonly used as an indicator of central nervous system integrity, little is currently understood about the mechanisms that determine processing time. In the current study, we are interested in determining the differences in electrophysiological events associated with significant changes in reaction time that could be elicited by changes in stimulus intensity. The primary objective is to assess the effect of increasing stimulus intensity on the latency and amplitude of afferent inputs to the somatosensory cortex, and their relation to reaction time. Methods Median nerve stimulation was applied to the non-dominant hand of 12 healthy young adults at two different stimulus intensities (HIGH & LOW). Participants were asked to either press a button as fast as possible with their dominant hand or remain quiet following the stimulus. Electroencephalography was used to measure somatosensory evoked potentials (SEPs) and event related potentials (ERPs). Electromyography from the flexor digitorum superficialis of the button-pressing hand was used to assess reaction time. Response time was the time of button press. Results Reaction time and response time were significantly shorter following the HIGH intensity stimulus compared to the LOW intensity stimulus. There were no differences in SEP (N20 & P24) peak latencies and peak-to-peak amplitude for the two stimulus intensities. ERPs, locked to response time, demonstrated a significantly larger pre-movement negativity to positivity following the HIGH intensity stimulus over the Cz electrode. Discussion This work demonstrates that rapid reaction times are not attributable to the latency of afferent processing from the stimulated site to the somatosensory cortex, and those latency reductions occur further along the sensorimotor transformation pathway. Evidence from ERPs indicates that frontal planning areas such as the supplementary motor area may play a role in transforming the elevated sensory
Probabilistic encoding of stimulus strength in astrocyte global calcium signals.
Croft, Wayne; Reusch, Katharina; Tilunaite, Agne; Russell, Noah A; Thul, Rüdiger; Bellamy, Tomas C
2016-04-01
Astrocyte calcium signals can range in size from subcellular microdomains to waves that spread through the whole cell (and into connected cells). The differential roles of such local or global calcium signaling are under intense investigation, but the mechanisms by which local signals evolve into global signals in astrocytes are not well understood, nor are the computational rules by which physiological stimuli are transduced into a global signal. To investigate these questions, we transiently applied receptor agonists linked to calcium signaling to primary cultures of cerebellar astrocytes. Astrocytes repetitively tested with the same stimulus responded with global signals intermittently, indicating that each stimulus had a defined probability for triggering a response. The response probability varied between agonists, increased with agonist concentration, and could be positively and negatively modulated by crosstalk with other signaling pathways. To better understand the processes determining the evolution of a global signal, we recorded subcellular calcium "puffs" throughout the whole cell during stimulation. The key requirement for puffs to trigger a global calcium wave following receptor activation appeared to be the synchronous release of calcium from three or more sites, rather than an increasing calcium load accumulating in the cytosol due to increased puff size, amplitude, or frequency. These results suggest that the concentration of transient stimuli will be encoded into a probability of generating a global calcium response, determined by the likelihood of synchronous release from multiple subcellular sites. © 2015 Wiley Periodicals, Inc.
Generalization of a tactile stimulus in horses.
Dougherty, D M; Lewis, P
1993-05-01
Using horses, we investigated the control of operant behavior by a tactile stimulus (the training stimulus) and the generalization of behavior to six other similar test stimuli. In a stall, the experimenters mounted a response panel in the doorway. Located on this panel were a response lever and a grain dispenser. The experimenters secured a tactile-stimulus belt to the horse's back. The stimulus belt was constructed by mounting seven solenoids along a piece of burlap in a manner that allowed each to provide the delivery of a tactile stimulus, a repetitive light tapping, at different locations (spaced 10.0 cm apart) along the horse's back. Two preliminary steps were necessary before generalization testing: training a measurable response (lip pressing) and training on several reinforcement schedules in the presence of a training stimulus (tapping by one of the solenoids). We then gave each horse two generalization test sessions. Results indicated that the horses' behavior was effectively controlled by the training stimulus. Horses made the greatest number of responses to the training stimulus, and the tendency to respond to the other test stimuli diminished as the stimuli became farther away from the training stimulus. These findings are discussed in the context of behavioral principles and their relevance to the training of horses.
Stimulus specificity of a steady-state visual-evoked potential-based brain-computer interface
Ng, Kian B.; Bradley, Andrew P.; Cunnington, Ross
2012-06-01
The mechanisms of neural excitation and inhibition when given a visual stimulus are well studied. It has been established that changing stimulus specificity such as luminance contrast or spatial frequency can alter the neuronal activity and thus modulate the visual-evoked response. In this paper, we study the effect that stimulus specificity has on the classification performance of a steady-state visual-evoked potential-based brain-computer interface (SSVEP-BCI). For example, we investigate how closely two visual stimuli can be placed before they compete for neural representation in the cortex and thus influence BCI classification accuracy. We characterize stimulus specificity using the four stimulus parameters commonly encountered in SSVEP-BCI design: temporal frequency, spatial size, number of simultaneously displayed stimuli and their spatial proximity. By varying these quantities and measuring the SSVEP-BCI classification accuracy, we are able to determine the parameters that provide optimal performance. Our results show that superior SSVEP-BCI accuracy is attained when stimuli are placed spatially more than 5° apart, with size that subtends at least 2° of visual angle, when using a tagging frequency of between high alpha and beta band. These findings may assist in deciding the stimulus parameters for optimal SSVEP-BCI design.
CPM Test-Retest Reliability: "Standard" vs "Single Test-Stimulus" Protocols.
Granovsky, Yelena; Miller-Barmak, Adi; Goldstein, Oren; Sprecher, Elliot; Yarnitsky, David
2016-03-01
Assessment of pain inhibitory mechanisms using conditioned pain modulation (CPM) is relevant clinically in prediction of pain and analgesic efficacy. Our objective is to provide necessary estimates of intersession CPM reliability, to enable transformation of the CPM paradigm into a clinical tool. Two cohorts of young healthy subjects (N = 65) participated in two dual-session studies. In Study I, a Bath-Thermode CPM protocol was used, with hot water immersion and contact heat as conditioning- and test-stimuli, respectively, in a classical parallel CPM design introducing test-stimulus first, and then the conditioning- and repeated test-stimuli in parallel. Study II consisted of two CPM protocols: 1) Two-Thermodes, one for each of the stimuli, in the same parallel design as above, and 2) single test-stimulus (STS) protocol with a single administration of a contact heat test-stimulus, partially overlapped in time by a remote shorter contact heat as conditioning stimulus. Test-retest reliability was assessed within 3-7 days. The STS-CPM had superior reliability intraclass correlation (ICC 2 ,: 1 = 0.59) over Bath-Thermode (ICC 2 ,: 1 = 0.34) or Two-Thermodes (ICC 2 ,: 1 = 0.21) protocols. The hand immersion conditioning pain had higher reliability than thermode pain (ICC 2 ,: 1 = 0.76 vs ICC 2 ,: 1 = 0.16). Conditioned test-stimulus pain scores were of good (ICC 2 ,: 1 = 0.62) or fair (ICC 2 ,: 1 = 0.43) reliability for the Bath-Thermode and the STS, respectively, but not for the Two-Thermodes protocol (ICC 2 ,: 1 = 0.20). The newly developed STS-CPM paradigm was more reliable than other CPM protocols tested here, and should be further investigated for its clinical relevance. It appears that large contact size of the conditioning-stimulus and use of single rather than dual test-stimulus pain contribute to augmentation of CPM reliability. © 2015 American Academy of Pain Medicine. All rights reserved. For permissions, please e
Stipica, I; Pavlinac Dodig, I; Pecotic, R; Dogas, Z; Valic, Z; Valic, M
2016-01-01
This study was undertaken to determine pattern sensitivity of phrenic nerve plasticity in respect to different respiratory challenges. We compared long-term effects of intermittent and continuous hypercapnic and hypoxic stimuli, and combined intermittent hypercapnia and hypoxia on phrenic nerve plasticity. Adult, male, urethane-anesthetized, vagotomized, paralyzed, mechanically ventilated Sprague-Dawley rats were exposed to: acute intermittent hypercapnia (AIHc or AIHc(O2)), acute intermittent hypoxia (AIH), combined intermittent hypercapnia and hypoxia (AIHcH), continuous hypercapnia (CHc), or continuous hypoxia (CH). Peak phrenic nerve activity (pPNA) and burst frequency were analyzed during baseline (T0), hypercapnia or hypoxia exposures, at 15, 30, and 60 min (T60) after the end of the stimulus. Exposure to acute intermittent hypercapnia elicited decrease of phrenic nerve frequency from 44.25+/-4.06 at T0 to 35.29+/-5.21 at T60, (P=0.038, AIHc) and from 45.5+/-2.62 to 37.17+/-3.68 breaths/min (P=0.049, AIHc(O2)), i.e. frequency phrenic long term depression was induced. Exposure to AIH elicited increase of pPNA at T60 by 141.0+/-28.2 % compared to baseline (P=0.015), i.e. phrenic long-term facilitation was induced. Exposure to AIHcH, CHc, or CH protocols failed to induce long-term plasticity of the phrenic nerve. Thus, we conclude that intermittency of the hypercapnic or hypoxic stimuli is needed to evoke phrenic nerve plasticity.
Parallel and orthogonal stimulus in ultradiluted neural networks
International Nuclear Information System (INIS)
Sobral, G. A. Jr.; Vieira, V. M.; Lyra, M. L.; Silva, C. R. da
2006-01-01
Extending a model due to Derrida, Gardner, and Zippelius, we have studied the recognition ability of an extreme and asymmetrically diluted version of the Hopfield model for associative memory by including the effect of a stimulus in the dynamics of the system. We obtain exact results for the dynamic evolution of the average network superposition. The stimulus field was considered as proportional to the overlapping of the state of the system with a particular stimulated pattern. Two situations were analyzed, namely, the external stimulus acting on the initialization pattern (parallel stimulus) and the external stimulus acting on a pattern orthogonal to the initialization one (orthogonal stimulus). In both cases, we obtained the complete phase diagram in the parameter space composed of the stimulus field, thermal noise, and network capacity. Our results show that the system improves its recognition ability for parallel stimulus. For orthogonal stimulus two recognition phases emerge with the system locking at the initialization or stimulated pattern. We confront our analytical results with numerical simulations for the noiseless case T=0
Adaptive stimulus optimization for sensory systems neuroscience
DiMattina, Christopher; Zhang, Kechen
2013-01-01
In this paper, we review several lines of recent work aimed at developing practical methods for adaptive on-line stimulus generation for sensory neurophysiology. We consider various experimental paradigms where on-line stimulus optimization is utilized, including the classical optimal stimulus paradigm where the goal of experiments is to identify a stimulus which maximizes neural responses, the iso-response paradigm which finds sets of stimuli giving rise to constant responses, and the system...
Response to various periods of mechanical stimuli in Physarum plasmodium
International Nuclear Information System (INIS)
Umedachi, Takuya; Ito, Kentaro; Kobayashi, Ryo; Ishiguro, Akio; Nakagaki, Toshiyuki
2017-01-01
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. (paper)
The stimulus integration area for horizontal vergence.
Allison, Robert S; Howard, Ian P; Fang, Xueping
2004-06-01
Over what region of space are horizontal disparities integrated to form the stimulus for vergence? The vergence system might be expected to respond to disparities within a small area of interest to bring them into the range of precise stereoscopic processing. However, the literature suggests that disparities are integrated over a fairly large parafoveal area. We report the results of six experiments designed to explore the spatial characteristics of the stimulus for vergence. Binocular eye movements were recorded using magnetic search coils. Each dichoptic display consisted of a central target stimulus that the subject attempted to fuse, and a competing stimulus with conflicting disparity. In some conditions the target was stationary, providing a fixation stimulus. In other conditions, the disparity of the target changed to provide a vergence-tracking stimulus. The target and competing stimulus were combined in a variety of conditions including those in which (1) a transparent textured-disc target was superimposed on a competing textured background, (2) a textured-disc target filled the centre of a competing annular background, and (3) a small target was presented within the centre of a competing annular background of various inner diameters. In some conditions the target and competing stimulus were separated in stereoscopic depth. The results are consistent with a disparity integration area with a diameter of about 5 degrees. Stimuli beyond this integration area can drive vergence in their own right, but they do not appear to be summed or averaged with a central stimulus to form a combined disparity signal. A competing stimulus had less effect on vergence when separated from the target by a disparity pedestal. As a result, we propose that it may be more useful to think in terms of an integration volume for vergence rather than a two-dimensional retinal integration area.
Adaptive stimulus optimization for sensory systems neuroscience.
DiMattina, Christopher; Zhang, Kechen
2013-01-01
In this paper, we review several lines of recent work aimed at developing practical methods for adaptive on-line stimulus generation for sensory neurophysiology. We consider various experimental paradigms where on-line stimulus optimization is utilized, including the classical optimal stimulus paradigm where the goal of experiments is to identify a stimulus which maximizes neural responses, the iso-response paradigm which finds sets of stimuli giving rise to constant responses, and the system identification paradigm where the experimental goal is to estimate and possibly compare sensory processing models. We discuss various theoretical and practical aspects of adaptive firing rate optimization, including optimization with stimulus space constraints, firing rate adaptation, and possible network constraints on the optimal stimulus. We consider the problem of system identification, and show how accurate estimation of non-linear models can be highly dependent on the stimulus set used to probe the network. We suggest that optimizing stimuli for accurate model estimation may make it possible to successfully identify non-linear models which are otherwise intractable, and summarize several recent studies of this type. Finally, we present a two-stage stimulus design procedure which combines the dual goals of model estimation and model comparison and may be especially useful for system identification experiments where the appropriate model is unknown beforehand. We propose that fast, on-line stimulus optimization enabled by increasing computer power can make it practical to move sensory neuroscience away from a descriptive paradigm and toward a new paradigm of real-time model estimation and comparison.
Generalization of a tactile stimulus in horses.
Dougherty, D M; Lewis, P
1993-01-01
Using horses, we investigated the control of operant behavior by a tactile stimulus (the training stimulus) and the generalization of behavior to six other similar test stimuli. In a stall, the experimenters mounted a response panel in the doorway. Located on this panel were a response lever and a grain dispenser. The experimenters secured a tactile-stimulus belt to the horse's back. The stimulus belt was constructed by mounting seven solenoids along a piece of burlap in a manner that allowed...
Stimulus-Response Compatibility effect in the near-far dimension: A developmental study
Directory of Open Access Journals (Sweden)
Aurélien Richez
2016-08-01
Full Text Available The present study investigates the developmental aspect of stimulus-response compatibility effect in 8 to 11-years-old children. The task consisted in manually responding to the colour of a pawn presented on a chessboard at different distances. Manual responses were provided by reaching a proximal or distal location depending on the colour of the stimulus. We found that reaction time was affected by the conflict generated by the response suggested by the location of the stimulus and the response required according to its colour. This was not the case for movement time despite we found a higher rate of long duration movements in the incongruent than in the congruent spatial condition. The SRC effect was however observed in children older than 10 years old. These findings provide additional evidence for a reorganization of the perceptual system during the period of 8 to 10 years, integrating progressively multimodal information and preparing more efficiently the body to act in the environment.
Ward, Ryan D; Gallistel, C R; Jensen, Greg; Richards, Vanessa L; Fairhurst, Stephen; Balsam, Peter D
2012-07-01
In a conditioning protocol, the onset of the conditioned stimulus ([CS]) provides information about when to expect reinforcement (unconditioned stimulus [US]). There are two sources of information from the CS in a delay conditioning paradigm in which the CS-US interval is fixed. The first depends on the informativeness, the degree to which CS onset reduces the average expected time to onset of the next US. The second depends only on how precisely a subject can represent a fixed-duration interval (the temporal Weber fraction). In three experiments with mice, we tested the differential impact of these two sources of information on rate of acquisition of conditioned responding (CS-US associability). In Experiment 1, we showed that associability (the inverse of trials to acquisition) increased in proportion to informativeness. In Experiment 2, we showed that fixing the duration of the US-US interval or the CS-US interval or both had no effect on associability. In Experiment 3, we equated the increase in information produced by varying the C/T ratio with the increase produced by fixing the duration of the CS-US interval. Associability increased with increased informativeness, but, as in Experiment 2, fixing the CS-US duration had no effect on associability. These results are consistent with the view that CS-US associability depends on the increased rate of reward signaled by CS onset. The results also provide further evidence that conditioned responding is temporally controlled when it emerges.
International Nuclear Information System (INIS)
Christofek, L.; Rapidis, P.; Reinhard, A.; Fermilab
2005-01-01
The Stimulus Test Stand was originally constructed and assembled for testing the SVX2 ASIC readout and then upgraded for SVX3 ASIC prototyping and testing. We have modified this system for SVX4 ASIC [1] prototype testing. We described the individual components below. Additional details for other hardware for SVX4 testing can be found in reference [2]. We provide a description of the Stimulus Test Stand used for prototype testing of the SVX4 chip
Crago, Patrick E; Makowski, Nathaniel S
2014-10-01
Stimulation of peripheral nerves is often superimposed on ongoing motor and sensory activity in the same axons, without a quantitative model of the net action potential train at the axon endpoint. We develop a model of action potential patterns elicited by superimposing constant frequency axonal stimulation on the action potentials arriving from a physiologically activated neural source. The model includes interactions due to collision block, resetting of the neural impulse generator, and the refractory period of the axon at the point of stimulation. Both the mean endpoint firing rate and the probability distribution of the action potential firing periods depend strongly on the relative firing rates of the two sources and the intersite conduction time between them. When the stimulus rate exceeds the neural rate, neural action potentials do not reach the endpoint and the rate of endpoint action potentials is the same as the stimulus rate, regardless of the intersite conduction time. However, when the stimulus rate is less than the neural rate, and the intersite conduction time is short, the two rates partially sum. Increases in stimulus rate produce non-monotonic increases in endpoint rate and continuously increasing block of neurally generated action potentials. Rate summation is reduced and more neural action potentials are blocked as the intersite conduction time increases. At long intersite conduction times, the endpoint rate simplifies to being the maximum of either the neural or the stimulus rate. This study highlights the potential of increasing the endpoint action potential rate and preserving neural information transmission by low rate stimulation with short intersite conduction times. Intersite conduction times can be decreased with proximal stimulation sites for muscles and distal stimulation sites for sensory endings. The model provides a basis for optimizing experiments and designing neuroprosthetic interventions involving motor or sensory stimulation.
VARIASI STIMULUS DALAM PELATIHAN KEWIRAUSAHAAN STIMULUS VARIATION IN ENTREPRENEURSHIP TRAINING
Directory of Open Access Journals (Sweden)
Sarippudin Sarippudin
2017-11-01
Full Text Available Entrepreneurship training aims to prepare participants for entrepreneurship. This training is important because entrepreneurship is not an easy case. Training becomes a way to inculcate the entrepreneurial mentality to be determined to start a business, to face some risks and to be tenacious. In order to create this training succeed, instructors as training spearheads must have skills in conveying materials, even inspiring the participants. The stimulus variation is a form of instructors’ skill. Stimulus variation makes the learning process works well the training becomes fun, so that participants can be comfortable and voluntarily follow the learning process. Training is not a monotonous activity. The instructor can be an inspiration in the classroom, no longer just as a transmitter of learning materials.
Glucocorticoids mediate stress-induced impairment of retrieval of stimulus-response memory.
Atsak, Piray; Guenzel, Friederike M; Kantar-Gok, Deniz; Zalachoras, Ioannis; Yargicoglu, Piraye; Meijer, Onno C; Quirarte, Gina L; Wolf, Oliver T; Schwabe, Lars; Roozendaal, Benno
2016-05-01
Acute stress and elevated glucocorticoid hormone levels are well known to impair the retrieval of hippocampus-dependent 'declarative' memory. Recent findings suggest that stress might also impair the retrieval of non-hippocampal memories. In particular, stress shortly before retention testing was shown to impair the retrieval of striatal stimulus-response associations in humans. However, the mechanism underlying this stress-induced retrieval impairment of non-hippocampal stimulus-response memory remains elusive. In the present study, we investigated whether an acute elevation in glucocorticoid levels mediates the impairing effects of stress on retrieval of stimulus-response memory. Male Sprague-Dawley rats were trained on a stimulus-response task in an eight-arm radial maze until they learned to associate a stimulus, i.e., cue, with a food reward in one of the arms. Twenty-four hours after successful acquisition, they received a systemic injection of vehicle, corticosterone (1mg/kg), the corticosterone-synthesis inhibitor metyrapone (35mg/kg) or were left untreated 1h before retention testing. We found that the corticosterone injection impaired the retrieval of stimulus-response memory. We further found that the systemic injection procedure per se was stressful as the vehicle administration also increased plasma corticosterone levels and impaired the retrieval of stimulus-response memory. However, memory retrieval was not impaired when rats were tested 2min after the systemic vehicle injection, before any stress-induced elevation in corticosterone levels had occurred. Moreover, metyrapone treatment blocked the effect of injection stress on both plasma corticosterone levels and memory retrieval impairment, indicating that the endogenous corticosterone response mediates the stress-induced memory retrieval impairment. None of the treatments affected rats' locomotor activity or motivation to search for the food reward within the maze. These findings show that stress
Working memory delay period activity marks a domain-unspecific attention mechanism.
Katus, Tobias; Müller, Matthias M
2016-03-01
Working memory (WM) recruits neural circuits that also perform perception- and action-related functions. Among the functions that are shared between the domains of WM and perception is selective attention, which supports the maintenance of task-relevant information during the retention delay of WM tasks. The tactile contralateral delay activity (tCDA) component of the event-related potential (ERP) marks the attention-based rehearsal of tactile information in somatosensory brain regions. We tested whether the tCDA reflects the competition for shared attention resources between a WM task and a perceptual task under dual-task conditions. The two tasks were always performed on opposite hands. In different blocks, the WM task had higher or lower priority than the perceptual task. The tCDA's polarity consistently reflected the hand where the currently prioritized task was performed. This suggests that the process indexed by the tCDA is not specific to the domain of WM, but mediated by a domain-unspecific attention mechanism. The analysis of transient ERP components evoked by stimuli in the two tasks further supports the interpretation that the tCDA marks a goal-directed bias in the allocation of selective attention. Larger spatially selective modulations were obtained for stimulus material related to the high-, as compared to low-priority, task. While our results generally indicate functional overlap between the domains of WM and perception, we also found evidence suggesting that selection in internal (mnemonic) and external (perceptual) stimulus representations involves processes that are not active during shifts of preparatory attention. Copyright © 2016 Elsevier Inc. All rights reserved.
Different responses of spontaneous and stimulus-related alpha activity to ambient luminance changes.
Benedetto, Alessandro; Lozano-Soldevilla, Diego; VanRullen, Rufin
2017-12-04
Alpha oscillations are particularly important in determining our percepts and have been implicated in fundamental brain functions. Oscillatory activity can be spontaneous or stimulus-related. Furthermore, stimulus-related responses can be phase- or non-phase-locked to the stimulus. Non-phase-locked (induced) activity can be identified as the average amplitude changes in response to a stimulation, while phase-locked activity can be measured via reverse-correlation techniques (echo function). However, the mechanisms and the functional roles of these oscillations are far from clear. Here, we investigated the effect of ambient luminance changes, known to dramatically modulate neural oscillations, on spontaneous and stimulus-related alpha. We investigated the effect of ambient luminance on EEG alpha during spontaneous human brain activity at rest (experiment 1) and during visual stimulation (experiment 2). Results show that spontaneous alpha amplitude increased by decreasing ambient luminance, while alpha frequency remained unaffected. In the second experiment, we found that under low-luminance viewing, the stimulus-related alpha amplitude was lower, and its frequency was slightly faster. These effects were evident in the phase-locked part of the alpha response (echo function), but weaker or absent in the induced (non-phase-locked) alpha responses. Finally, we explored the possible behavioural correlates of these modulations in a monocular critical flicker frequency task (experiment 3), finding that dark adaptation in the left eye decreased the temporal threshold of the right eye. Overall, we found that ambient luminance changes impact differently on spontaneous and stimulus-related alpha expression. We suggest that stimulus-related alpha activity is crucial in determining human temporal segmentation abilities. © 2017 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.
Chiang, Hsueh-Sheng; Eroh, Justin; Spence, Jeffrey S; Motes, Michael A; Maguire, Mandy J; Krawczyk, Daniel C; Brier, Matthew R; Hart, John; Kraut, Michael A
2016-08-01
How the brain combines the neural representations of features that comprise an object in order to activate a coherent object memory is poorly understood, especially when the features are presented in different modalities (visual vs. auditory) and domains (verbal vs. nonverbal). We examined this question using three versions of a modified Semantic Object Retrieval Test, where object memory was probed by a feature presented as a written word, a spoken word, or a picture, followed by a second feature always presented as a visual word. Participants indicated whether each feature pair elicited retrieval of the memory of a particular object. Sixteen subjects completed one of the three versions (N=48 in total) while their EEG were recorded simultaneously. We analyzed EEG data in four separate frequency bands (delta: 1-4Hz, theta: 4-7Hz; alpha: 8-12Hz; beta: 13-19Hz) using a multivariate data-driven approach. We found that alpha power time-locked to response was modulated by both cross-modality (visual vs. auditory) and cross-domain (verbal vs. nonverbal) probing of semantic object memory. In addition, retrieval trials showed greater changes in all frequency bands compared to non-retrieval trials across all stimulus types in both response-locked and stimulus-locked analyses, suggesting dissociable neural subcomponents involved in binding object features to retrieve a memory. We conclude that these findings support both modality/domain-dependent and modality/domain-independent mechanisms during semantic object memory retrieval. Copyright © 2016 Elsevier B.V. All rights reserved.
Gibson, Brett M; Wasserman, Edward A
2003-01-01
The authors taught pigeons to discriminate displays of 16 identical items from displays of 16 nonidentical items. Unlike most same-different discrimination studies--where only stimulus relations could serve a discriminative function--both the identity of the items and the relations among the items were discriminative features of the displays. The pigeons learned about both stimulus identity and stimulus relations when these 2 sources of information served as redundant, relevant cues. In tests of associative competition, identity cues exerted greater stimulus control than relational cues. These results suggest that the pigeon can respond to both specific stimuli and general relations in the environment.
Searching for the optimal stimulus eliciting auditory brainstem responses in humans
DEFF Research Database (Denmark)
Fobel, Oliver; Dau, Torsten
2004-01-01
-chirp, was based on estimates of human basilar membrane (BM) group delays derived from stimulus-frequency otoacoustic emissions (SFOAE) at a sound pressure level of 40 dB [Shera and Guinan, in Recent Developments in Auditory Mechanics (2000)]. The other chirp, referred to as the A-chirp, was derived from latency...
Directory of Open Access Journals (Sweden)
Christina F Lavallee
whereby the most infrequent stimulus demanded inhibition, indicating that the frequency of the stop-signal interacts with the current stimulus-response contingency. These results demonstrate that response inhibition is prone to influence from other cognitive functions, making it difficult to dissociate real inhibitory capabilities from the influence of moderating mechanisms.
Stahl, Christoph; Unkelbach, Christian; Corneille, Olivier
2009-09-01
Evaluative conditioning (EC) is a central mechanism for both classic and current theories of attitude formation. In contrast to Pavlovian conditioning, it is often conceptualized as a form of evaluative learning that occurs without awareness of the conditioned stimulus-unconditioned stimulus (CS-US) contingencies. In the present research, the authors directly address this point by assessing the respective roles of US valence awareness and US identity awareness in attitude formation through EC. Across 4 experiments, EC was assessed with evaluative ratings as well as evaluative priming measures, and the impact of valence and identity awareness on EC was evaluated. EC effects on priming and rating measures occurred only for CSs for which participants could report the associated US valence, and US identity awareness did not further contribute to EC. This finding was obtained both for semantically meaningless (i.e., nonword letter sequences) and meaningful (i.e., consumer products) CSs. These results provide further support for the critical role of contingency awareness in EC, albeit valence awareness, not identity awareness. (c) 2009 APA, all rights reserved).
The Possible Role of CO2 in Producing A Post-Stimulus CBF and BOLD Undershoot
Yücel, Meryem A.; Devor, Anna; Akin, Ata; Boas, David A.
2009-01-01
Comprehending the underlying mechanisms of neurovascular coupling is important for understanding the pathogenesis of neurodegenerative diseases related to uncoupling. Moreover, it elucidates the casual relation between the neural signaling and the hemodynamic responses measured with various imaging modalities such as functional magnetic resonance imaging (fMRI). There are mainly two hypotheses concerning this mechanism: a metabolic hypothesis and a neurogenic hypothesis. We have modified recent models of neurovascular coupling adding the effects of both NO (nitric oxide) kinetics, which is a well-known neurogenic vasodilator, and CO2 kinetics as a metabolic vasodilator. We have also added the Hodgkin–Huxley equations relating the membrane potentials to sodium influx through the membrane. Our results show that the dominant factor in the hemodynamic response is NO, however CO2 is important in producing a brief post-stimulus undershoot in the blood flow response that in turn modifies the fMRI blood oxygenation level-dependent post-stimulus undershoot. Our results suggest that increased cerebral blood flow during stimulation causes CO2 washout which then results in a post-stimulus hypocapnia induced vasoconstrictive effect. PMID:20027233
Completo, A; Bandeiras, C; Fonseca, F
2017-06-01
A well-established cue for improving the properties of tissue-engineered cartilage is mechanical stimulation. However, the explicit ranges of mechanical stimuli that correspond to favorable metabolic outcomes are elusive. Usually, these outcomes have only been associated with the applied strain and frequency, an oversimplification that can hide the fundamental relationship between the intrinsic mechanical stimuli and the metabolic outcomes. This highlights two important key issues: the firstly is related to the evaluation of the intrinsic mechanical stimuli of native cartilage; the second, assuming that the intrinsic mechanical stimuli will be important, deals with the ability to replicate them on the tissue-engineered constructs. This study quantifies and compares the volume of cartilage and agarose subjected to a given magnitude range of each intrinsic mechanical stimulus, through a numerical simulation of a patient-specific knee model coupled with experimental data of contact during the stance phase of gait, and agarose constructs under direct-dynamic compression. The results suggest that direct compression loading needs to be parameterized with time-dependence during the initial culture period in order to better reproduce each one of the intrinsic mechanical stimuli developed in the patient-specific cartilage. A loading regime which combines time periods of low compressive strain (5%) and frequency (0.5Hz), in order to approach the maximal principal strain and fluid velocity stimulus of the patient-specific cartilage, with time periods of high compressive strain (20%) and frequency (3Hz), in order to approach the pore pressure values, may be advantageous relatively to a single loading regime throughout the full culture period. Copyright © 2017 IPEM. Published by Elsevier Ltd. All rights reserved.
Ogawa, Masaaki
2017-11-01
In response to changing internal and external situations, we always need to adapt our behavior based on previous experiences, particularly, acquired stimulus-outcome information. The orbitofrontal cortex (OFC), a prefrontal cortical region, is critical for this type of decision-making. The current understanding of the fundamental functions of the OFC has been reviewed by introducing, as an example, how the OFC contributes to the processing of uncertain rewards. Furthermore, the importance of revealing context and temporally specific causal roles of neural circuits including the OFC in decision-making, as well as the techniques to achieve the goal, have been discussed.
Carrieroa, A; Pereirab, A F; Wilson, A J; Castagno, S; Javaheri, B; Pitsillides, A A; Marenzana, M; Shefelbine, S J
2018-06-01
Bone is a dynamic tissue and adapts its architecture in response to biological and mechanical factors. Here we investigate how cortical bone formation is spatially controlled by the local mechanical environment in the murine tibia axial loading model (C57BL/6). We obtained 3D locations of new bone formation by performing 'slice and view' 3D fluorochrome mapping of the entire bone and compared these sites with the regions of high fluid velocity or strain energy density estimated using a finite element model, validated with ex-vivo bone surface strain map acquired ex-vivo using digital image correlation. For the comparison, 2D maps of the average bone formation and peak mechanical stimulus on the tibial endosteal and periosteal surface across the entire cortical surface were created. Results showed that bone formed on the periosteal and endosteal surface in regions of high fluid flow. Peak strain energy density predicted only the formation of bone periosteally. Understanding how the mechanical stimuli spatially relates with regions of cortical bone formation in response to loading will eventually guide loading regime therapies to maintain or restore bone mass in specific sites in skeletal pathologies.
Directory of Open Access Journals (Sweden)
Bernaba M
2014-11-01
Full Text Available Mario Bernaba, Kevin A Johnson, Jiang-Ti Kong, Sean MackeyStanford Systems Neuroscience and Pain Laboratory, Department of Anesthesiology, Perioperative and Pain Medicine, Stanford University School of Medicine, Stanford, CA, USAPurpose: Conditioned pain modulation (CPM is an experimental approach for probing endogenous analgesia by which one painful stimulus (the conditioning stimulus may inhibit the perceived pain of a subsequent stimulus (the test stimulus. Animal studies suggest that CPM is mediated by a spino–bulbo–spinal loop using objective measures such as neuronal firing. In humans, pain ratings are often used as the end point. Because pain self-reports are subject to cognitive influences, we tested whether cognitive factors would impact on CPM results in healthy humans.Methods: We conducted a within-subject, crossover study of healthy adults to determine the extent to which CPM is affected by 1 threatening and reassuring evaluation and 2 imagery alone of a cold conditioning stimulus. We used a heat stimulus individualized to 5/10 on a visual analog scale as the testing stimulus and computed the magnitude of CPM by subtracting the postconditioning rating from the baseline pain rating of the heat stimulus.Results: We found that although evaluation can increase the pain rating of the conditioning stimulus, it did not significantly alter the magnitude of CPM. We also found that imagery of cold pain alone did not result in statistically significant CPM effect.Conclusion: Our results suggest that CPM is primarily dependent on sensory input, and that the cortical processes of evaluation and imagery have little impact on CPM. These findings lend support for CPM as a useful tool for probing endogenous analgesia through subcortical mechanisms.Keywords: conditioned pain modulation, endogenous analgesia, evaluation, imagery, cold presser test, CHEPS, contact heat-evoked potential stimulator
Characterization of the discriminative stimulus produced by the dopamine antagonist tiapride.
Cohen, C; Sanger, D J; Perrault, G
1997-11-01
The ability of tiapride, a selective D2/D3 dopamine receptor antagonist, to exert discriminative stimulus control of responding was investigated by training rats to discriminate this drug (30 mg/kg) from saline in a two-lever, food-reinforcement procedure. Acquisition of tiapride discrimination required a relatively lengthy training period (mean of 76 sessions) but stable performance was maintained throughout the 18- month study. The dose of tiapride eliciting 50% tiapride-lever choice (ED50) was 2.2 mg/kg. After determination of the dose-effect curve with tiapride, substitution tests with several dopamine antagonists and other reference compounds were performed. All dopamine antagonists, including amisulpride (ED50 4 mg/kg), sulpiride (18 mg/kg), sultopride (1.5 mg/kg), clebopride (0.13 mg/kg), raclopride (0.16 mg/kg), metoclopramide (1.4 mg/kg), remoxipride (4.8 mg/kg), pimozide (2.7 mg/kg), thioridazine (3.4 mg/kg), olanzapine (0.97 mg/kg), chlorpromazine (1.9 mg/kg), risperidone (0.22 mg/kg) and haloperidol (0.14 mg/kg), except clozapine (>10 mg/kg), produced dose-dependent substitution for tiapride. Tiapride-like stimulus effects were observed at doses that decreased response rates. However, ED50 values for substitution by tiapride, amisulpride, sulpiride, sultopride, pimozide, clebopride and thioridazine were lower than ED50 values for decreasing responding. Additional studies were conducted to evaluate the ability of direct and indirect dopamine agonists to attenuate the tiapride discriminative stimulus. Pretreatment with d-amphetamine and nomifensine antagonized the discriminative stimulus effects of tiapride. Quinpirole, 7-OH-DPAT, bromocriptine and apomorphine partially blocked the stimulus effects of tiapride whereas SKF 38393 did not affect the discrimination. These results from substitution and antagonism tests indicated that the discriminative effects of tiapride are mediated by activity at D2/D3 dopamine receptors.
Utilization of reward-prospect enhances preparatory attention and reduces stimulus conflict.
van den Berg, Berry; Krebs, Ruth M; Lorist, Monicque M; Woldorff, Marty G
2014-06-01
The prospect of gaining money is an incentive widely at play in the real world. Such monetary motivation might have particularly strong influence when the cognitive system is challenged, such as when needing to process conflicting stimulus inputs. Here, we employed manipulations of reward-prospect and attentional-preparation levels in a cued-Stroop stimulus conflict task, along with the high temporal resolution of electrical brain recordings, to provide insight into the mechanisms by which reward-prospect and attention interact and modulate cognitive task performance. In this task, the cue indicated whether or not the participant needed to prepare for an upcoming Stroop stimulus and, if so, whether there was the potential for monetary reward (dependent on performance on that trial). Both cued attention and cued reward-prospect enhanced preparatory neural activity, as reflected by increases in the hallmark attention-related negative-polarity ERP slow wave (contingent negative variation [CNV]) and reductions in oscillatory Alpha activity, which was followed by enhanced processing of the subsequent Stroop stimulus. In addition, similar modulations of preparatory neural activity (larger CNVs and reduced Alpha) predicted shorter versus longer response times (RTs) to the subsequent target stimulus, consistent with such modulations reflecting trial-to-trial variations in attention. Particularly striking were the individual differences in the utilization of reward-prospect information. In particular, the size of the reward effects on the preparatory neural activity correlated across participants with the degree to which reward-prospect both facilitated overall task performance (shorter RTs) and reduced conflict-related behavioral interference. Thus, the prospect of reward appears to recruit attentional preparation circuits to enhance processing of task-relevant target information.
Stimulus Probability Effects in Absolute Identification
Kent, Christopher; Lamberts, Koen
2016-01-01
This study investigated the effect of stimulus presentation probability on accuracy and response times in an absolute identification task. Three schedules of presentation were used to investigate the interaction between presentation probability and stimulus position within the set. Data from individual participants indicated strong effects of…
Pre-stimulus BOLD-network activation modulates EEG spectral activity during working memory retention
Directory of Open Access Journals (Sweden)
Mara eKottlow
2015-05-01
Full Text Available Working memory (WM processes depend on our momentary mental state and therefore exhibit considerable fluctuations. Here, we investigate the interplay of task-preparatory and task-related brain activity as represented by pre-stimulus BOLD-fluctuations and spectral EEG from the retention periods of a visual WM task. Visual WM is used to maintain sensory information in the brain enabling the performance of cognitive operations and is associated with mental health.We tested 22 subjects simultaneously with EEG and fMRI while performing a visuo-verbal Sternberg task with two different loads, allowing for the temporal separation of preparation, encoding, retention and retrieval periods.Four temporally coherent networks - the default mode network (DMN, the dorsal attention, the right and the left WM network - were extracted from the continuous BOLD data by means of a group ICA. Subsequently, the modulatory effect of these networks’ pre-stimulus activation upon retention-related EEG activity in the theta, alpha and beta frequencies was analyzed. The obtained results are informative in the context of state-dependent information processing.We were able to replicate two well-known load-dependent effects: the frontal-midline theta increase during the task and the decrease of pre-stimulus DMN activity. As our main finding, these two measures seem to depend on each other as the significant negative correlations at frontal-midline channels suggested. Thus, suppressed pre-stimulus DMN levels facilitated later task related frontal midline theta increases. In general, based on previous findings that neuronal coupling in different frequency bands may underlie distinct functions in WM retention, our results suggest that processes reflected by spectral oscillations during retention seem not only to be online synchronized with activity in different attention-related networks but are also modulated by activity in these networks during preparation intervals.
Mückschel, Moritz; Dippel, Gabriel; Beste, Christian
2017-11-01
Response inhibition mechanisms are mediated via cortical and subcortical networks. At the cortical level, the superior frontal gyrus, including the supplementary motor area (SMA) and inferior frontal areas, is important. There is an ongoing debate about the functional roles of these structures during response inhibition as it is unclear whether these structures process different codes or contents of information during response inhibition. In the current study, we examined this question with a focus on theta frequency oscillations during response inhibition processes. We used a standard Go/Nogo task in a sample of human participants and combined different EEG signal decomposition methods with EEG beamforming approaches. The results suggest that stimulus coding during inhibitory control is attained by oscillations in the upper theta frequency band (∼7 Hz). In contrast, response selection codes during inhibitory control appear to be attained by the lower theta frequency band (∼4 Hz). Importantly, these different codes seem to be processed in distinct functional neuroanatomical structures. Although the SMA may process stimulus codes and response selection codes, the inferior frontal cortex may selectively process response selection codes during inhibitory control. Taken together, the results suggest that different entities within the functional neuroanatomical network associated with response inhibition mechanisms process different kinds of codes during inhibitory control. These codes seem to be reflected by different oscillations within the theta frequency band. Hum Brain Mapp 38:5681-5690, 2017. © 2017 Wiley-Liss, Inc. © 2017 Wiley Periodicals, Inc.
Geometric mechanics of periodic pleated origami.
Wei, Z Y; Guo, Z V; Dudte, L; Liang, H Y; Mahadevan, L
2013-05-24
Origami structures are mechanical metamaterials with properties that arise almost exclusively from the geometry of the constituent folds and the constraint of piecewise isometric deformations. Here we characterize the geometry and planar and nonplanar effective elastic response of a simple periodically folded Miura-ori structure, which is composed of identical unit cells of mountain and valley folds with four-coordinated ridges, defined completely by two angles and two lengths. We show that the in-plane and out-of-plane Poisson's ratios are equal in magnitude, but opposite in sign, independent of material properties. Furthermore, we show that effective bending stiffness of the unit cell is singular, allowing us to characterize the two-dimensional deformation of a plate in terms of a one-dimensional theory. Finally, we solve the inverse design problem of determining the geometric parameters for the optimal geometric and mechanical response of these extreme structures.
DEFF Research Database (Denmark)
Christensen, Anders Tornvig; Ordoñez, Rodrigo Pizarro; Hammershøi, Dorte
2014-01-01
ratios f2/f1 (1.05-1.50) and three stimulus sound pressure levels L1/L2 (65/45, 65/55, 70/60) were measured in each configuration. The DPOAE response was isolated with the discrete Fourier transformation (DFT). The DFT measures the DPOAE response accurately only when the DPOAE frequency and both stimulus...... examples of low-frequency DPOAEs exist in the literature. Overcoming the decreasing response level and increasing noise level with decreasing frequency may provide a non-invasive window into the inner-ear mechanics of low-frequency hearing. Eighteen out of 21 young human adults screened (19-30 years) had......-frequency range. The stimulus level has similar effects in both frequency ranges, that is, the ratio-magnitude response increases and broadens with increasing level. The combined observations could indicate a difference between apical and basal cochlear physiology....
Tsaltas, E; Schugens, M M; Gray, J A
1989-01-01
The aim of the experiment was to determine whether the dorsal noradrenergic bundle (DB) plays a role in conditioning to context. Rats received either bilateral lesions of the DB by local injection of 6-hydroxydopamine, vehicle injections only, or sham operations. All animals were then trained to barpress for food on a variable interval (VI) schedule. Two 5-min intrusion periods were superimposed on the VI baseline during each session. An 'envelope' stimulus (flashing light) was on throughout each intrusion period. In addition, embedded in the two intrusion periods of each session, there occurred 8 presentations of a 'punctate' conditioned stimulus (CS) (a 15-s clicker), and 8 presentations of a 0.5-s footshock. Within each surgical condition rats were randomly allocated to one of three conditioning groups, receiving 100%, 50% or 0% temporal association between CS and shock. Conditioning to the punctate CS and to the context provided by the envelope stimulus was assessed by the degree of suppression of the barpress response relative to the VI baseline. Responding was most suppressed in the punctate CS in the 100 and 50% conditions, and most suppressed in the envelope stimulus in the 0% condition. DB lesions released response suppression to the punctate CS, had no effect on suppression to the envelope stimulus, and reduced sensitivity to CS-shock probability as measured by response suppression during the punctate CS. These results confirm previous reports that DB lesions alleviate response suppression to shock-associated cues, identify some of the parameters that affect this phenomenon, but fail to support a role for the DB in contextual conditioning.
Hahn, Britta; Ross, Thomas J; Wolkenberg, Frank A; Shakleya, Diaa M; Huestis, Marilyn A; Stein, Elliot A
2009-09-01
Attention-enhancing effects of nicotine appear to depend on the nature of the attentional function. Underlying neuroanatomical mechanisms, too, may vary depending on the function modulated. This functional magnetic resonance imaging study recorded blood oxygen level-dependent (BOLD) activity in minimally deprived smokers during tasks of simple stimulus detection, selective attention, or divided attention after single-blind application of a transdermal nicotine (21 mg) or placebo patch. Smokers' performance in the placebo condition was unimpaired as compared with matched nonsmokers. Nicotine reduced reaction time (RT) in the stimulus detection and selective attention but not divided attention condition. Across all task conditions, nicotine reduced activation in frontal, temporal, thalamic, and visual regions and enhanced deactivation in so-called "default" regions. Thalamic effects correlated with RT reduction selectively during stimulus detection. An interaction with task condition was observed in middle and superior frontal gyri, where nicotine reduced activation only during stimulus detection. A visuomotor control experiment provided evidence against nonspecific effects of nicotine. In conclusion, although prefrontal activity partly displayed differential modulation by nicotine, most BOLD effects were identical across tasks, despite differential performance effects, suggesting that common neuronal mechanisms can selectively benefit different attentional functions. Overall, the effects of nicotine may be explained by increased functional efficiency and downregulated task-independent "default" functions.
Intranasal localizability of odorants: influence of stimulus volume.
Frasnelli, J; Hummel, T; Berg, J; Huang, G; Doty, R L
2011-05-01
When an odorant is presented to one side of the nose and air to the other, the ability to localize which side received the odorant depends upon trigeminal nerve stimulation. It has been shown that performance on this lateralization task increases as stimulus concentration increases. In this study, we determined the influences of stimulus volume and sex on the ability to localize each of 8 odorants presented at neat concentrations: anethole, geraniol, limonene, linalool, menthol, methyl salicylate, phenyl ethanol, and vanillin. At a low stimulus volume (11 mL), only menthol was localized at an above-chance level. At a high stimulus volume (21 mL), above-chance localization occurred for all odorants except vanillin. Women were significantly better than men in localizing menthol. Stimuli rated as most intense were those that were most readily localized. The detection performance measures, as well as rated intensity values, significantly correlated with earlier findings of the trigeminal detectability of odorants presented to anosmic and normosmic subjects. This study suggests that differences in stimulus volume may explain some discrepant findings within the trigeminal chemosensory literature and supports the concept that vanillin may be a "relatively pure" olfactory stimulus.
Stimulus-dependent effects on tactile spatial acuity
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Tommerdahl M
2005-10-01
Full Text Available Abstract Background Previous studies have shown that spatio-tactile acuity is influenced by the clarity of the cortical response in primary somatosensory cortex (SI. Stimulus characteristics such as frequency, amplitude, and location of tactile stimuli presented to the skin have been shown to have a significant effect on the response in SI. The present study observes the effect of changing stimulus parameters of 25 Hz sinusoidal vertical skin displacement stimulation ("flutter" on a human subject's ability to discriminate between two adjacent or near-adjacent skin sites. Based on results obtained from recent neurophysiological studies of the SI response to different conditions of vibrotactile stimulation, we predicted that the addition of 200 Hz vibration to the same site that a two-point flutter stimulus was delivered on the skin would improve a subject's spatio-tactile acuity over that measured with flutter alone. Additionally, similar neurophysiological studies predict that the presence of either a 25 Hz flutter or 200 Hz vibration stimulus on the unattended hand (on the opposite side of the body from the site of two-point limen testing – the condition of bilateral stimulation – which has been shown to evoke less SI cortical activity than the contralateral-only stimulus condition would decrease a subject's ability to discriminate between two points on the skin. Results A Bekesy tracking method was employed to track a subject's ability to discriminate between two-point stimuli delivered to the skin. The distance between the two points of stimulation was varied on a trial-by-trial basis, and several different stimulus conditions were examined: (1 The "control" condition, in which 25 Hz flutter stimuli were delivered simultaneously to the two points on the skin of the attended hand, (2 the "complex" condition, in which a combination of 25 Hz flutter and 200 Hz vibration stimuli were delivered to the two points on the attended hand, and (3 a
DeLeon, Iser G.; Toole, Lisa M.; Gutshall, Katharine A.; Bowman, Lynn G.
2005-01-01
Recent studies have used pretreatment analyses, termed competing stimulus assessments, to identify items that most effectively displace the aberrant behavior of individuals with developmental disabilities. In most studies, there appeared to have been no systematic basis for selecting the sampling period (ranging from 30 s to 10 min) in which items…
Parametric study of control mechanism of cortical bone remodeling under mechanical stimulus
Wang, Yanan; Qin, Qing-Hua
2010-03-01
The control mechanism of mechanical bone remodeling at cellular level was investigated by means of an extensive parametric study on a theoretical model described in this paper. From a perspective of control mechanism, it was found that there are several control mechanisms working simultaneously in bone remodeling which is a complex process. Typically, an extensive parametric study was carried out for investigating model parameter space related to cell differentiation and apoptosis which can describe the fundamental cell lineage behaviors. After analyzing all the combinations of 728 permutations in six model parameters, we have identified a small number of parameter combinations that can lead to physiologically realistic responses which are similar to theoretically idealized physiological responses. The results presented in the work enhanced our understanding on mechanical bone remodeling and the identified control mechanisms can help researchers to develop combined pharmacological-mechanical therapies to treat bone loss diseases such as osteoporosis.
Bai, Yu; Nakao, Takashi; Xu, Jiameng; Qin, Pengmin; Chaves, Pedro; Heinzel, Alexander; Duncan, Niall; Lane, Timothy; Yen, Nai-Shing; Tsai, Shang-Yueh; Northoff, Georg
2016-01-01
Recent studies have demonstrated neural overlap between resting state activity and self-referential processing. This "rest-self" overlap occurs especially in anterior cortical midline structures like the perigenual anterior cingulate cortex (PACC). However, the exact neurotemporal and biochemical mechanisms remain to be identified. Therefore, we conducted a combined electroencephalography (EEG)-magnetic resonance spectroscopy (MRS) study. EEG focused on pre-stimulus (e.g., prior to stimulus presentation or perception) power changes to assess the degree to which those changes can predict subjects' perception (and judgment) of subsequent stimuli as high or low self-related. MRS measured resting state concentration of glutamate, focusing on PACC. High pre-stimulus (e.g., prior to stimulus presentation or perception) alpha power significantly correlated with both perception of stimuli judged to be highly self-related and with resting state glutamate concentrations in the PACC. In sum, our results show (i) pre-stimulus (e.g., prior to stimulus presentation or perception) alpha power and resting state glutamate concentration to mediate rest-self overlap that (ii) dispose or incline subjects to assign high degrees of self-relatedness to perceptual stimuli.
[Microcomputer control of a LED stimulus display device].
Ohmoto, S; Kikuchi, T; Kumada, T
1987-02-01
A visual stimulus display system controlled by a microcomputer was constructed at low cost. The system consists of a LED stimulus display device, a microcomputer, two interface boards, a pointing device (a "mouse") and two kinds of software. The first software package is written in BASIC. Its functions are: to construct stimulus patterns using the mouse, to construct letter patterns (alphabet, digit, symbols and Japanese letters--kanji, hiragana, katakana), to modify the patterns, to store the patterns on a floppy disc, to translate the patterns into integer data which are used to display the patterns in the second software. The second software package, written in BASIC and machine language, controls display of a sequence of stimulus patterns in predetermined time schedules in visual experiments.
Self-isospectral periodic potentials and supersymmetric quantum mechanics
International Nuclear Information System (INIS)
Dunne, G.; Feinberg, J.
1998-01-01
We discuss supersymmetric quantum mechanical models with periodic potentials. The important new feature is that it is possible for both isospectral potentials to support zero modes, in contrast with the standard nonperiodic case where either one or neither (but not both) of the isospectral pair has a zero mode. Thus it is possible to have supersymmetry unbroken and yet also have a vanishing Witten index. We present some explicit exactly soluble examples for which the isospectral potentials have identical band spectra, and which are open-quotes self-isospectralclose quotes in the sense that the potentials have identical shape, but are translated by one half-period relative to one another. copyright 1997 The American Physical Society
Smith, A; Pedler, A
2018-01-01
Various conditioned pain modulation (CPM) methodologies have been used to investigate diffuse noxious inhibitory control pain mechanisms in healthy and clinical populations. Occlusion cuff parameters have been poorly studied. We aimed to investigate whether occlusion cuff intensity and/or duration influenced CPM magnitudes. We also investigated the role of physical activity levels on CPM magnitude. Two studies were performed to investigate the role of intensity and duration of occlusion cuff conditioning stimulus on test stimulus (tibialis anterior pressure pain thresholds). In Study 1, conditioning stimulus intensity of 2/10 or 5/10 (duration CPM magnitude. In Study 1, 27 healthy volunteers (mean ± SD: 24.9 years (±4.5); eight female) demonstrated that an occlusion cuff applied to the upper arm eliciting 5/10 local pain resulted in a significant (mean ± SD: 17% ± 46%) increase in CPM magnitude, when compared to 2/10 intensity (-3% ± 38%, p = 0.026), whereas in Study 2, 25 healthy volunteers (22.5 years (±2.7); 13 female) demonstrated that 3 min of 2/10 CS intensity did not result in a significant change in CPM (p = 0.21). There was no significant relationship between physical activity levels and CPM in either study (p > 0.22). This study demonstrated that an occlusion cuff of 5/10 conditioning stimulus intensity, when compared to 2/10, significantly increased CPM magnitude. Maintaining 2/10 conditioning stimulus for 3 min did not increase CPM magnitude. Dysfunctional conditioned pain modulation (CPM) has been associated with poor health outcomes. Various factors can influence CPM outcomes. The role of occlusion cuff conditioning stimulus intensity and duration has not been previously investigated. Intensity (5/10), but not duration of lower intensity (2/10) conditioning stimulus, affects CPM magnitude. © 2017 European Pain Federation - EFIC®.
Visual awareness suppression by pre-stimulus brain stimulation; a neural effect.
Jacobs, Christianne; Goebel, Rainer; Sack, Alexander T
2012-01-02
Transcranial magnetic stimulation (TMS) has established the functional relevance of early visual cortex (EVC) for visual awareness with great temporal specificity non-invasively in conscious human volunteers. Many studies have found a suppressive effect when TMS was applied over EVC 80-100 ms after the onset of the visual stimulus (post-stimulus TMS time window). Yet, few studies found task performance to also suffer when TMS was applied even before visual stimulus presentation (pre-stimulus TMS time window). This pre-stimulus TMS effect, however, remains controversially debated and its origin had mainly been ascribed to TMS-induced eye-blinking artifacts. Here, we applied chronometric TMS over EVC during the execution of a visual discrimination task, covering an exhaustive range of visual stimulus-locked TMS time windows ranging from -80 pre-stimulus to 300 ms post-stimulus onset. Electrooculographical (EoG) recordings, sham TMS stimulation, and vertex TMS stimulation controlled for different types of non-neural TMS effects. Our findings clearly reveal TMS-induced masking effects for both pre- and post-stimulus time windows, and for both objective visual discrimination performance and subjective visibility. Importantly, all effects proved to be still present after post hoc removal of eye blink trials, suggesting a neural origin for the pre-stimulus TMS suppression effect on visual awareness. We speculate based on our data that TMS exerts its pre-stimulus effect via generation of a neural state which interacts with subsequent visual input. Copyright © 2011 Elsevier Inc. All rights reserved.
Rational-emotive behavior therapy and the formation of stimulus equivalence classes.
Plaud, J J; Gaither, G A; Weller, L A; Bigwood, S J; Barth, J; von Duvillard, S P
1998-08-01
Stimulus equivalence is a behavioral approach to analyzing the "meaning" of stimulus sets and has an implication for clinical psychology. The formation of three-member (A --> B --> C) stimulus equivalence classes was used to investigate the effects of three different sets of sample and comparison stimuli on emergent behavior. The three stimulus sets were composed of Rational-Emotive Behavior Therapy (REBT)-related words, non-REBT emotionally charged words, and a third category of neutral words composed of flower labels. Sixty-two women and men participated in a modified matching-to-sample experiment. Using a mixed cross-over design, and controlling for serial order effects, participants received conditional training and emergent relationship training in the three stimulus set conditions. Results revealed a significant interaction between the formation of stimulus equivalence classes and stimulus meaning, indicating consistently biased responding in favor of reaching criterion responding more slowly for REBT-related and non-REBT emotionally charged words. Results were examined in the context of an analysis of the importance of stimulus meaning on behavior and the relation of stimulus meaning to behavioral and cognitive theories, with special appraisal given to the influence of fear-related discriminative stimuli on behavior.
Alterations to multisensory and unisensory integration by stimulus competition.
Pluta, Scott R; Rowland, Benjamin A; Stanford, Terrence R; Stein, Barry E
2011-12-01
In environments containing sensory events at competing locations, selecting a target for orienting requires prioritization of stimulus values. Although the superior colliculus (SC) is causally linked to the stimulus selection process, the manner in which SC multisensory integration operates in a competitive stimulus environment is unknown. Here we examined how the activity of visual-auditory SC neurons is affected by placement of a competing target in the opposite hemifield, a stimulus configuration that would, in principle, promote interhemispheric competition for access to downstream motor circuitry. Competitive interactions between the targets were evident in how they altered unisensory and multisensory responses of individual neurons. Responses elicited by a cross-modal stimulus (multisensory responses) proved to be substantially more resistant to competitor-induced depression than were unisensory responses (evoked by the component modality-specific stimuli). Similarly, when a cross-modal stimulus served as the competitor, it exerted considerably more depression than did its individual component stimuli, in some cases producing more depression than predicted by their linear sum. These findings suggest that multisensory integration can help resolve competition among multiple targets by enhancing orientation to the location of cross-modal events while simultaneously suppressing orientation to events at alternate locations.
Directory of Open Access Journals (Sweden)
Alexia Bourgeois
Full Text Available In order to behave adaptively, attention can be directed in space either voluntarily (i.e., endogenously according to strategic goals, or involuntarily (i.e., exogenously through reflexive capture by salient or novel events. The emotional or motivational value of stimuli can also strongly influence attentional orienting. However, little is known about how reward-related effects compete or interact with endogenous and exogenous attention mechanisms, particularly outside of awareness. Here we developed a visual search paradigm to study subliminal value-based attentional orienting. We systematically manipulated goal-directed or stimulus-driven attentional orienting and examined whether an irrelevant, but previously rewarded stimulus could compete with both types of spatial attention during search. Critically, reward was learned without conscious awareness in a preceding phase where one among several visual symbols was consistently paired with a subliminal monetary reinforcement cue. Our results demonstrated that symbols previously associated with a monetary reward received higher attentional priority in the subsequent visual search task, even though these stimuli and reward were no longer task-relevant, and despite reward being unconsciously acquired. Thus, motivational processes operating independent of conscious awareness may provide powerful influences on mechanisms of attentional selection, which could mitigate both stimulus-driven and goal-directed shifts of attention.
Bourgeois, Alexia; Neveu, Rémi; Vuilleumier, Patrik
2016-01-01
In order to behave adaptively, attention can be directed in space either voluntarily (i.e., endogenously) according to strategic goals, or involuntarily (i.e., exogenously) through reflexive capture by salient or novel events. The emotional or motivational value of stimuli can also strongly influence attentional orienting. However, little is known about how reward-related effects compete or interact with endogenous and exogenous attention mechanisms, particularly outside of awareness. Here we developed a visual search paradigm to study subliminal value-based attentional orienting. We systematically manipulated goal-directed or stimulus-driven attentional orienting and examined whether an irrelevant, but previously rewarded stimulus could compete with both types of spatial attention during search. Critically, reward was learned without conscious awareness in a preceding phase where one among several visual symbols was consistently paired with a subliminal monetary reinforcement cue. Our results demonstrated that symbols previously associated with a monetary reward received higher attentional priority in the subsequent visual search task, even though these stimuli and reward were no longer task-relevant, and despite reward being unconsciously acquired. Thus, motivational processes operating independent of conscious awareness may provide powerful influences on mechanisms of attentional selection, which could mitigate both stimulus-driven and goal-directed shifts of attention.
Detecting method for crude oil price fluctuation mechanism under different periodic time series
International Nuclear Information System (INIS)
Gao, Xiangyun; Fang, Wei; An, Feng; Wang, Yue
2017-01-01
Highlights: • We proposed the concept of autoregressive modes to indicate the fluctuation patterns. • We constructed transmission networks for studying the fluctuation mechanism. • There are different fluctuation mechanism under different periodic time series. • Only a few types of autoregressive modes control the fluctuations in crude oil price. • There are cluster effects during the fluctuation mechanism of autoregressive modes. - Abstract: Current existing literatures can characterize the long-term fluctuation of crude oil price time series, however, it is difficult to detect the fluctuation mechanism specifically under short term. Because each fluctuation pattern for one short period contained in a long-term crude oil price time series have dynamic characteristics of diversity; in other words, there exhibit various fluctuation patterns in different short periods and transmit to each other, which reflects the reputedly complicate and chaotic oil market. Thus, we proposed an incorporated method to detect the fluctuation mechanism, which is the evolution of the different fluctuation patterns over time from the complex network perspective. We divided crude oil price time series into segments using sliding time windows, and defined autoregressive modes based on regression models to indicate the fluctuation patterns of each segment. Hence, the transmissions between different types of autoregressive modes over time form a transmission network that contains rich dynamic information. We then capture transmission characteristics of autoregressive modes under different periodic time series through the structure features of the transmission networks. The results indicate that there are various autoregressive modes with significantly different statistical characteristics under different periodic time series. However, only a few types of autoregressive modes and transmission patterns play a major role in the fluctuation mechanism of the crude oil price, and these
Strategic allocation of attention reduces temporally predictable stimulus conflict
Appelbaum, L. Gregory; Boehler, Carsten N.; Won, Robert; Davis, Lauren; Woldorff, Marty G.
2013-01-01
Humans are able to continuously monitor environmental situations and adjust their behavioral strategies to optimize performance. Here we investigate the behavioral and brain adjustments that occur when conflicting stimulus elements are, or are not, temporally predictable. Event-related potentials (ERPs) were collected while manual-response variants of the Stroop task were performed in which the stimulus onset asynchronies (SOAs) between the relevant-color and irrelevant-word stimulus components were either randomly intermixed, or held constant, within each experimental run. Results indicated that the size of both the neural and behavioral effects of stimulus incongruency varied with the temporal arrangement of the stimulus components, such that the random-SOA arrangements produced the greatest incongruency effects at the earliest irrelevant-first SOA (−200 ms) and the constant-SOA arrangements produced the greatest effects with simultaneous presentation. These differences in conflict processing were accompanied by rapid (~150 ms) modulations of the sensory ERPs to the irrelevant distracter components when they occurred consistently first. These effects suggest that individuals are able to strategically allocate attention in time to mitigate the influence of a temporally predictable distracter. As these adjustments are instantiated by the subjects without instruction, they reveal a form of rapid strategic learning for dealing with temporally predictable stimulus incongruency. PMID:22360623
Mechanical Engineering Department technical abstracts for the period January-June 1985
International Nuclear Information System (INIS)
Woo, H.H.
1986-01-01
This document contains the abstracts from 116 reports produced by the Mechanical Engineering Department of the Lawrence Livermore National Laboratory during the period January - June, 1985. The Mechanical Engineering Department is reponsible for the design, analysis, fabrication, testing, and field installation of all mechanical components and systems required by Defence Systems, Lasers, Magnetic Fusion Energy, Physics, and Biomedical and Environmental Research. Similar support is provided to the Chemistry and Computation Departments. Keyword, author, and report-number indices are included
Pérez-Díaz, Francisco; Díaz, Estrella; Sánchez, Natividad; Vargas, Juan Pedro; Pearce, John M.; López, Juan Carlos
2017-01-01
Recent studies support the idea that stimulus processing in latent inhibition can vary during the course of preexposure. Controlled attentional mechanisms are said to be important in the early stages of preexposure, while in later stages animals adopt automatic processing of the stimulus to be used for conditioning. Given this distinction, it is possible that both types of processing are governed by different neural systems, affecting differentially the retrieval of information about the stim...
StimDuino: an Arduino-based electrophysiological stimulus isolator.
Sheinin, Anton; Lavi, Ayal; Michaelevski, Izhak
2015-03-30
Electrical stimulus isolator is a widely used device in electrophysiology. The timing of the stimulus application is usually automated and controlled by the external device or acquisition software; however, the intensity of the stimulus is adjusted manually. Inaccuracy, lack of reproducibility and no automation of the experimental protocol are disadvantages of the manual adjustment. To overcome these shortcomings, we developed StimDuino, an inexpensive Arduino-controlled stimulus isolator allowing highly accurate, reproducible automated setting of the stimulation current. The intensity of the stimulation current delivered by StimDuino is controlled by Arduino, an open-source microcontroller development platform. The automatic stimulation patterns are software-controlled and the parameters are set from Matlab-coded simple, intuitive and user-friendly graphical user interface. The software also allows remote control of the device over the network. Electrical current measurements showed that StimDuino produces the requested current output with high accuracy. In both hippocampal slice and in vivo recordings, the fEPSP measurements obtained with StimDuino and the commercial stimulus isolators showed high correlation. Commercial stimulus isolators are manually managed, while StimDuino generates automatic stimulation patterns with increasing current intensity. The pattern is utilized for the input-output relationship analysis, necessary for assessment of excitability. In contrast to StimuDuino, not all commercial devices are capable for remote control of the parameters and stimulation process. StimDuino-generated automation of the input-output relationship assessment eliminates need for the current intensity manually adjusting, improves stimulation reproducibility, accuracy and allows on-site and remote control of the stimulation parameters. Copyright © 2015 Elsevier B.V. All rights reserved.
Javitt, D C; Grochowski, S; Shelley, A M; Ritter, W
1998-03-01
Schizophrenia is a severe mental disorder associated with disturbances in perception and cognition. Event-related potentials (ERP) provide a mechanism for evaluating potential mechanisms underlying neurophysiological dysfunction in schizophrenia. Mismatch negativity (MMN) is a short-duration auditory cognitive ERP component that indexes operation of the auditory sensory ('echoic') memory system. Prior studies have demonstrated impaired MMN generation in schizophrenia along with deficits in auditory sensory memory performance. MMN is elicited in an auditory oddball paradigm in which a sequence of repetitive standard tones is interrupted infrequently by a physically deviant ('oddball') stimulus. The present study evaluates MMN generation as a function of deviant stimulus probability, interstimulus interval, interdeviant interval and the degree of pitch separation between the standard and deviant stimuli. The major findings of the present study are first, that MMN amplitude is decreased in schizophrenia across a broad range of stimulus conditions, and second, that the degree of deficit in schizophrenia is largest under conditions when MMN is normally largest. The pattern of deficit observed in schizophrenia differs from the pattern observed in other conditions associated with MMN dysfunction, including Alzheimer's disease, stroke, and alcohol intoxication.
Positive and negative affect produce opposing task-irrelevant stimulus preexposure effects.
Lazar, Josef; Kaplan, Oren; Sternberg, Terri; Lubow, R E
2012-06-01
In three experiments, groups were exposed to either positive or negative affect video clips, after which they were presented with a series of task-irrelevant stimuli. In the subsequent test task, subjects were required to learn an association between the previously irrelevant stimulus and a consequence, and between a new stimulus and a consequence. Induced positive affect produced a latent inhibition effect (poorer evidence of learning with the previously irrelevant stimulus than with the novel stimulus). In opposition to this, induced negative affect resulted in better evidence of learning with a previously irrelevant stimulus than with a novel stimulus. In general, the opposing effects also were present in participants scoring high on self-report questionnaires of depression (Experiments 2 and 3). These unique findings were predicted and accounted for on the basis of two principles: (a) positive affect broadens the attentional field and negative affect contracts it; and (b) task-irrelevant stimuli are processed in two successive stages, the first encodes stimulus properties, and the second encodes stimulus relationships. The opposing influences of negative and positive mood on the processing of irrelevant stimuli have implications for the role of emotion in general theories of cognition, and possibly for resolving some of the inconsistent findings in research with schizophrenia patients.
Auditory-visual stimulus pairing enhances perceptual learning in a songbird.
Hultsch; Schleuss; Todt
1999-07-01
In many oscine birds, song learning is affected by social variables, for example the behaviour of a tutor. This implies that both auditory and visual perceptual systems should be involved in the acquisition process. To examine whether and how particular visual stimuli can affect song acquisition, we tested the impact of a tutoring design in which the presentation of auditory stimuli (i.e. species-specific master songs) was paired with a well-defined nonauditory stimulus (i.e. stroboscope light flashes: Strobe regime). The subjects were male hand-reared nightingales, Luscinia megarhynchos. For controls, males were exposed to tutoring without a light stimulus (Control regime). The males' singing recorded 9 months later showed that the Strobe regime had enhanced the acquisition of song patterns. During this treatment birds had acquired more songs than during the Control regime; the observed increase in repertoire size was from 20 to 30% in most cases. Furthermore, the copy quality of imitations acquired during the Strobe regime was better than that of imitations developed from the Control regime, and this was due to a significant increase in the number of 'perfect' song copies. We conclude that these effects were mediated by an intrinsic component (e.g. attention or arousal) which specifically responded to the Strobe regime. Our findings also show that mechanisms of song learning are well prepared to process information from cross-modal perception. Thus, more detailed enquiries into stimulus complexes that are usually referred to as social variables are promising. Copyright 1999 The Association for the Study of Animal Behaviour.
Effects of Multimodal Presentation and Stimulus Familiarity on Auditory and Visual Processing
Robinson, Christopher W.; Sloutsky, Vladimir M.
2010-01-01
Two experiments examined the effects of multimodal presentation and stimulus familiarity on auditory and visual processing. In Experiment 1, 10-month-olds were habituated to either an auditory stimulus, a visual stimulus, or an auditory-visual multimodal stimulus. Processing time was assessed during the habituation phase, and discrimination of…
Stimulus-driven attentional capture by subliminal onset cues
Schoeberl, T.; Fuchs, I.; Theeuwes, J.; Ansorge, U.
2015-01-01
In two experiments, we tested whether subliminal abrupt onset cues capture attention in a stimulus-driven way. An onset cue was presented 16 ms prior to the stimulus display that consisted of clearly visible color targets. The onset cue was presented either at the same side as the target (the valid
Noradrenergic modulation of neural erotic stimulus perception.
Graf, Heiko; Wiegers, Maike; Metzger, Coraline Danielle; Walter, Martin; Grön, Georg; Abler, Birgit
2017-09-01
We recently investigated neuromodulatory effects of the noradrenergic agent reboxetine and the dopamine receptor affine amisulpride in healthy subjects on dynamic erotic stimulus processing. Whereas amisulpride left sexual functions and neural activations unimpaired, we observed detrimental activations under reboxetine within the caudate nucleus corresponding to motivational components of sexual behavior. However, broadly impaired subjective sexual functioning under reboxetine suggested effects on further neural components. We now investigated the same sample under these two agents with static erotic picture stimulation as alternative stimulus presentation mode to potentially observe further neural treatment effects of reboxetine. 19 healthy males were investigated under reboxetine, amisulpride and placebo for 7 days each within a double-blind cross-over design. During fMRI static erotic picture were presented with preceding anticipation periods. Subjective sexual functions were assessed by a self-reported questionnaire. Neural activations were attenuated within the caudate nucleus, putamen, ventral striatum, the pregenual and anterior midcingulate cortex and in the orbitofrontal cortex under reboxetine. Subjective diminished sexual arousal under reboxetine was correlated with attenuated neural reactivity within the posterior insula. Again, amisulpride left neural activations along with subjective sexual functioning unimpaired. Neither reboxetine nor amisulpride altered differential neural activations during anticipation of erotic stimuli. Our results verified detrimental effects of noradrenergic agents on neural motivational but also emotional and autonomic components of sexual behavior. Considering the overlap of neural network alterations with those evoked by serotonergic agents, our results suggest similar neuromodulatory effects of serotonergic and noradrenergic agents on common neural pathways relevant for sexual behavior. Copyright © 2017 Elsevier B.V. and
Psilocybin-induced stimulus control in the rat.
Winter, J C; Rice, K C; Amorosi, D J; Rabin, R A
2007-10-01
Although psilocybin has been trained in the rat as a discriminative stimulus, little is known of the pharmacological receptors essential for stimulus control. In the present investigation rats were trained with psilocybin and tests were then conducted employing a series of other hallucinogens and presumed antagonists. An intermediate degree of antagonism of psilocybin was observed following treatment with the 5-HT(2A) receptor antagonist, M100907. In contrast, no significant antagonism was observed following treatment with the 5-HT(1A/7) receptor antagonist, WAY-100635, or the DA D(2) antagonist, remoxipride. Psilocybin generalized fully to DOM, LSD, psilocin, and, in the presence of WAY-100635, DMT while partial generalization was seen to 2C-T-7 and mescaline. LSD and MDMA partially generalized to psilocybin and these effects were completely blocked by M-100907; no generalization of PCP to psilocybin was seen. The present data suggest that psilocybin induces a compound stimulus in which activity at the 5-HT(2A) receptor plays a prominent but incomplete role. In addition, psilocybin differs from closely related hallucinogens such as 5-MeO-DMT in that agonism at 5-HT(1A) receptors appears to play no role in psilocybin-induced stimulus control.
Psilocybin-induced stimulus control in the rat
Winter, J.C.; Rice, K.C.; Amorosi, D.J.; Rabin, R.A.
2007-01-01
Although psilocybin has been trained in the rat as a discriminative stimulus, little is known of the pharmacological receptors essential for stimulus control. In the present investigation rats were trained with psilocybin and tests were then conducted employing a series of other hallucinogens and presumed antagonists. An intermediate degree of antagonism of psilocybin was observed following treatment with the 5-HT2A receptor antagonist, M100907. In contrast, no significant antagonism was obse...
Retter, Talia L; Jiang, Fang; Webster, Michael A; Rossion, Bruno
2018-04-01
Fast periodic visual stimulation combined with electroencephalography (FPVS-EEG) has unique sensitivity and objectivity in measuring rapid visual categorization processes. It constrains image processing time by presenting stimuli rapidly through brief stimulus presentation durations and short inter-stimulus intervals. However, the selective impact of these temporal parameters on visual categorization is largely unknown. Here, we presented natural images of objects at a rate of 10 or 20 per second (10 or 20 Hz), with faces appearing once per second (1 Hz), leading to two distinct frequency-tagged EEG responses. Twelve observers were tested with three squarewave image presentation conditions: 1) with an ISI, a traditional 50% duty cycle at 10 Hz (50-ms stimulus duration separated by a 50-ms ISI); 2) removing the ISI and matching the rate, a 100% duty cycle at 10 Hz (100-ms duration with 0-ms ISI); 3) removing the ISI and matching the stimulus presentation duration, a 100% duty cycle at 20 Hz (50-ms duration with 0-ms ISI). The face categorization response was significantly decreased in the 20 Hz 100% condition. The conditions at 10 Hz showed similar face-categorization responses, peaking maximally over the right occipito-temporal (ROT) cortex. However, the onset of the 10 Hz 100% response was delayed by about 20 ms over the ROT region relative to the 10 Hz 50% condition, likely due to immediate forward-masking by preceding images. Taken together, these results help to interpret how the FPVS-EEG paradigm sets temporal constraints on visual image categorization. Copyright © 2018 Elsevier Ltd. All rights reserved.
Learning to fear a second-order stimulus following vicarious learning.
Reynolds, Gemma; Field, Andy P; Askew, Chris
2017-04-01
Vicarious fear learning refers to the acquisition of fear via observation of the fearful responses of others. The present study aims to extend current knowledge by exploring whether second-order vicarious fear learning can be demonstrated in children. That is, whether vicariously learnt fear responses for one stimulus can be elicited in a second stimulus associated with that initial stimulus. Results demonstrated that children's (5-11 years) fear responses for marsupials and caterpillars increased when they were seen with fearful faces compared to no faces. Additionally, the results indicated a second-order effect in which fear-related learning occurred for other animals seen together with the fear-paired animal, even though the animals were never observed with fearful faces themselves. Overall, the findings indicate that for children in this age group vicariously learnt fear-related responses for one stimulus can subsequently be observed for a second stimulus without it being experienced in a fear-related vicarious learning event. These findings may help to explain why some individuals do not recall involvement of a traumatic learning episode in the development of their fear of a specific stimulus.
Adaptive stimulus optimization and model-based experiments for sensory systems neuroscience
Directory of Open Access Journals (Sweden)
Christopher eDiMattina
2013-06-01
Full Text Available In this paper we review several lines of recent work aimed at developing practical methods for adaptive on-line stimulus generation for sensory neurophysiology. We consider various experimental paradigms where on-line stimulus optimization is utilized, including the classical textit{optimal stimulus} paradigm where the goal of experiments is to identify a stimulus which maximizes neural responses, the textit{iso-response} paradigm which finds sets of stimuli giving rise to constant responses, and the textit{system identification} paradigm where the experimental goal is to estimate and possibly compare sensory processing models. We discuss various theoretical and practical aspects of adaptive firing rate optimization, including optimization with stimulus space constraints, firing rate adaptation, and possible network constraints on the optimal stimulus. We consider the problem of system identification, and show how accurate estimation of nonlinear models can be highly dependent on the stimulus set used to probe the network. We suggest that optimizing stimuli for accurate model estimation may make it possible to successfully identify nonlinear models which are otherwise intractable, and summarize several recent studies of this type. Finally, we present a two-stage stimulus design procedure which combines the dual goals of model estimation and model comparison and may be especially useful for system identification experiments where the appropriate model is unknown beforehand. We propose that fast, on-line stimulus optimization enabled by increasing computer power can make it practical to move sensory neuroscience away from a descriptive paradigm and towards a new paradigm of real-time model estimation and comparison.
Dewey, James B; Dhar, Sumitrajit
2017-11-01
Behavioral hearing thresholds and otoacoustic emission (OAE) spectra often exhibit quasiperiodic fluctuations with frequency. For behavioral and OAE responses to single tones-the latter referred to as stimulus-frequency otoacoustic emissions (SFOAEs)-this microstructure has been attributed to intracochlear reflections of SFOAE energy between its region of generation and the middle ear boundary. However, the relationship between behavioral and SFOAE microstructures, as well as their presumed dependence on the properties of the SFOAE-generation mechanism, have yet to be adequately examined. To address this, behavioral thresholds and SFOAEs evoked by near-threshold tones were compared in 12 normal-hearing female subjects. The microstructures observed in thresholds and both SFOAE amplitudes and delays were found to be strikingly similar. SFOAE phase accumulated an integer number of cycles between the frequencies of microstructure maxima, consistent with a dependence of microstructure periodicity on SFOAE propagation delays. Additionally, microstructure depth was correlated with SFOAE magnitude in a manner resembling that predicted by the intracochlear reflection framework, after assuming reasonable values of parameters related to middle ear transmission. Further exploration of this framework may yield more precise estimates of such parameters and provide insight into their frequency dependence.
Evaluation of a Multiple-Stimulus Presentation Format for Assessing Reinforcer Preferences.
DeLeon, Iser G.; Iwata, Brian A.
1996-01-01
A study of seven adults with profound developmental disabilities compared methods for presenting stimuli during reinforcer-preference assessments. It found that a multiple-stimulus format in which selections were made without replacement may share the advantages of a paired-stimulus format and a multiple-stimulus format with replacement, while…
Leodori, Giorgio; Formica, Alessandra; Zhu, Xiaoying; Conte, Antonella; Belvisi, Daniele; Cruccu, Giorgio; Hallett, Mark; Berardelli, Alfredo
2017-10-01
The somatosensory temporal discrimination threshold (STDT) has been used in recent years to investigate time processing of sensory information, but little is known about the physiological correlates of somatosensory temporal discrimination. The objective of this study was to investigate whether the time interval required to discriminate between two stimuli varies according to the number of stimuli in the task. We used the third-stimulus temporal discrimination threshold (ThirdDT), defined as the shortest time interval at which an individual distinguishes a third stimulus following a pair of stimuli delivered at the STDT. The STDT and ThirdDT were assessed in 31 healthy subjects. In a subgroup of 10 subjects, we evaluated the effects of the stimuli intensity on the ThirdDT. In a subgroup of 16 subjects, we evaluated the effects of S1 continuous theta-burst stimulation (S1-cTBS) on the STDT and ThirdDT. Results show that ThirdDT is shorter than STDT. We found a positive correlation between STDT and ThirdDT values. As long as the stimulus intensity was within the perceivable and painless range, it did not affect ThirdDT values. S1-cTBS significantly affected both STDT and ThirdDT, although the latter was affected to a greater extent and for a longer period of time. We conclude that the interval needed to discriminate between time-separated tactile stimuli is related to the number of stimuli used in the task. STDT and ThirdDT are encoded in S1, probably by a shared tactile temporal encoding mechanism whose performance rapidly changes during the perception process. ThirdDT is a new method to measure somatosensory temporal discrimination. NEW & NOTEWORTHY To investigate whether the time interval required to discriminate between stimuli varies according to changes in the stimulation pattern, we used the third-stimulus temporal discrimination threshold (ThirdDT). We found that the somatosensory temporal discrimination acuity varies according to the number of stimuli in the
Pre-stimulus thalamic theta power predicts human memory formation.
Sweeney-Reed, Catherine M; Zaehle, Tino; Voges, Jürgen; Schmitt, Friedhelm C; Buentjen, Lars; Kopitzki, Klaus; Richardson-Klavehn, Alan; Hinrichs, Hermann; Heinze, Hans-Jochen; Knight, Robert T; Rugg, Michael D
2016-09-01
Pre-stimulus theta (4-8Hz) power in the hippocampus and neocortex predicts whether a memory for a subsequent event will be formed. Anatomical studies reveal thalamus-hippocampal connectivity, and lesion, neuroimaging, and electrophysiological studies show that memory processing involves the dorsomedial (DMTN) and anterior thalamic nuclei (ATN). The small size and deep location of these nuclei have limited real-time study of their activity, however, and it is unknown whether pre-stimulus theta power predictive of successful memory formation is also found in these subcortical structures. We recorded human electrophysiological data from the DMTN and ATN of 7 patients receiving deep brain stimulation for refractory epilepsy. We found that greater pre-stimulus theta power in the right DMTN was associated with successful memory encoding, predicting both behavioral outcome and post-stimulus correlates of successful memory formation. In particular, significant correlations were observed between right DMTN theta power and both frontal theta and right ATN gamma (32-50Hz) phase alignment, and frontal-ATN theta-gamma cross-frequency coupling. We draw the following primary conclusions. Our results provide direct electrophysiological evidence in humans of a role for the DMTN as well as the ATN in memory formation. Furthermore, prediction of subsequent memory performance by pre-stimulus thalamic oscillations provides evidence that post-stimulus differences in thalamic activity that index successful and unsuccessful encoding reflect brain processes specifically underpinning memory formation. Finally, the findings broaden the understanding of brain states that facilitate memory encoding to include subcortical as well as cortical structures. Copyright © 2016 Elsevier Inc. All rights reserved.
Model Stimulus-Organism-Response: Penentu Perilaku Pembelian Konsumen Secara Situasional
Magdalena, Nonie
2005-01-01
Understanding about consumer purchase behavior is an essential aspect for developing organization bussiness strategic, especially in retailing. S-O-R (Stimulus-Organism-Response) model helps the practision and academics to understand which stimulus will influence consumers and the reaction that comsumer gave. One of the stimulus that explained in this article is the situation. Situation is an aspect that had change and hardly to predict. In other words, situation will determine consumer purch...
Impact of stimulus uncanniness on speeded response
Directory of Open Access Journals (Sweden)
Kohske eTakahashi
2015-05-01
Full Text Available In the uncanny valley phenomenon, the causes of the feeling of uncanniness as well as the impact of the uncanniness on behavioral performances still remain open. The present study investigated the behavioral effects of stimulus uncanniness, particularly with respect to speeded response. Pictures of fish were used as visual stimuli. Participants engaged in direction discrimination, spatial cueing, and dot-probe tasks. The results showed that pictures rated as strongly uncanny delayed speeded response in the discrimination of the direction of the fish. In the cueing experiment, where a fish served as a task-irrelevant and unpredictable cue for a peripheral target, we again observed that the detection of a target was slowed when the cue was an uncanny fish. Conversely, the dot-probe task suggested that uncanny fish, unlike threatening stimulus, did not capture visual spatial attention. These results suggested that stimulus uncanniness resulted in the delayed response, and importantly this modulation was not mediated by the feelings of threat.
Stimulus-response coupling in platelets
International Nuclear Information System (INIS)
Huang, E.M.
1986-01-01
To understand the mechanism of stimulus-response coupling in platelets, the potentiating effect of succinate and lithium on platelet activation was examined. The action of succinate was immediate; preincubation with succinate did not lead to desensitization. Succinate was comparable to ADP in lowering cAMP levels previously elevated by PGl 2 . Since inhibition of cAMP is not a prerequisite for platelet activation, the mechanism of potentiation of succinate remains undefined. Lithium has also been shown to inhibit adenylate cyclase in PGl 2 -pretreated platelets. Lithium, however, can also inhibit inositol phosphate (InsP) phosphatase and lead to an accumulation of InsP. In human platelets, lithium also enhanced the thrombin-induced accumulation of [ 3 H]inositol-labelled inositol trisphosphate (InsP 3 ), and inositol bisphosphate (InsP 2 ). One hour after thrombin addition, all 3 inositol phosphates returned to near basal levels. In the presence of lithium, while labelled InsP 2 and InsP 3 returned to their respective basal levels, the InsP level remained elevated, consistent with the known inhibitory effect of lithium on InsP phosphatase. In thrombin-stimulated platelets prelabeled with [ 32 P]phosphate, lithium led to a decrease in labelled phosphatidylinositol 4-phosphate (PtdIns4P) as well as an enhanced production of labelled lysophosphatidylinositol, suggesting multiple effects of lithium on platelet phosphoinositide metabolism. These observed effects, however, occurred too slowly to be the mechanism by which lithium potentiated agonist-induced platelet activation. To study the agonist-receptor interaction, the effect of the specific, high affinity thrombin inhibitor, hirudin, on thrombin-induced accumulation of [ 3 H]inositol-labelled inositol phosphates was studied
Learning to fear a second-order stimulus following vicarious learning
Reynolds, G; Field, AP; Askew, C
2015-01-01
Vicarious fear learning refers to the acquisition of fear via observation of the fearful responses of others. The present study aims to extend current knowledge by exploring whether second-order vicarious fear learning can be demonstrated in children. That is, whether vicariously learnt fear responses for one stimulus can be elicited in a second stimulus associated with that initial stimulus. Results demonstrated that children’s (5–11 years) fear responses for marsupials and caterpillars incr...
Sylvester, Chad M; Hudziak, James J; Gaffrey, Michael S; Barch, Deanna M; Luby, Joan L
2016-02-01
Attention biases towards threatening and sad stimuli are associated with pediatric anxiety and depression, respectively. The basic cognitive mechanisms associated with attention biases in youth, however, remain unclear. Here, we tested the hypothesis that threat bias (selective attention for threatening versus neutral stimuli) but not sad bias relies on stimulus-driven attention. We collected measures of stimulus-driven attention, threat bias, sad bias, and current clinical symptoms in youth with a history of an anxiety disorder and/or depression (ANX/DEP; n = 40) as well as healthy controls (HC; n = 33). Stimulus-driven attention was measured with a non-emotional spatial orienting task, while threat bias and sad bias were measured at a short time interval (150 ms) with a spatial orienting task using emotional faces and at a longer time interval (500 ms) using a dot-probe task. In ANX/DEP but not HC, early attention bias towards threat was negatively correlated with later attention bias to threat, suggesting that early threat vigilance was associated with later threat avoidance. Across all subjects, stimulus-driven orienting was not correlated with early threat bias but was negatively correlated with later threat bias, indicating that rapid stimulus-driven orienting is linked to later threat avoidance. No parallel relationships were detected for sad bias. Current symptoms of depression but not anxiety were related to decreased stimulus-driven attention. Together, these results are consistent with the hypothesis that threat bias but not sad bias relies on stimulus-driven attention. These results inform the design of attention bias modification programs that aim to reverse threat biases and reduce symptoms associated with pediatric anxiety and depression.
Sylvester, Chad M.; Hudziak, James J.; Gaffrey, Michael S.; Barch, Deanna M.; Luby, Joan L.
2015-01-01
Attention biases towards threatening and sad stimuli are associated with pediatric anxiety and depression, respectively. The basic cognitive mechanisms associated with attention biases in youth, however, remain unclear. Here, we tested the hypothesis that threat bias (selective attention for threatening versus neutral stimuli) but not sad bias relies on stimulus-driven attention. We collected measures of stimulus-driven attention, threat bias, sad bias, and current clinical symptoms in youth with a history of an anxiety disorder and/or depression (ANX/DEP; n=40) as well as healthy controls (HC; n=33). Stimulus-driven attention was measured with a non-emotional spatial orienting task, while threat bias and sad bias were measured at a short time interval (150 ms) with a spatial orienting task using emotional faces and at a longer time interval (500 ms) using a dot-probe task. In ANX/DEP but not HC, early attention bias towards threat was negatively correlated with later attention bias to threat, suggesting that early threat vigilance was associated with later threat avoidance. Across all subjects, stimulus-driven orienting was not correlated with early threat bias but was negatively correlated with later threat bias, indicating that rapid stimulus-driven orienting is linked to later threat avoidance. No parallel relationships were detected for sad bias. Current symptoms of depression but not anxiety were related to decreased stimulus-driven attention. Together, these results are consistent with the hypothesis that threat bias but not sad bias relies on stimulus-driven attention. These results inform the design of attention bias modification programs that aim to reverse threat biases and reduce symptoms associated with pediatric anxiety and depression. PMID:25702927
Klink, P. Christiaan; Jeurissen, Danique; Theeuwes, Jan; Denys, Damiaan; Roelfsema, Pieter R.
2017-01-01
The richness of sensory input dictates that the brain must prioritize and select information for further processing and storage in working memory. Stimulus salience and reward expectations influence this prioritization but their relative contributions and underlying mechanisms are poorly understood.
The influence of spontaneous activity on stimulus processing in primary visual cortex.
Schölvinck, M L; Friston, K J; Rees, G
2012-02-01
Spontaneous activity in the resting human brain has been studied extensively; however, how such activity affects the local processing of a sensory stimulus is relatively unknown. Here, we examined the impact of spontaneous activity in primary visual cortex on neuronal and behavioural responses to a simple visual stimulus, using functional MRI. Stimulus-evoked responses remained essentially unchanged by spontaneous fluctuations, combining with them in a largely linear fashion (i.e., with little evidence for an interaction). However, interactions between spontaneous fluctuations and stimulus-evoked responses were evident behaviourally; high levels of spontaneous activity tended to be associated with increased stimulus detection at perceptual threshold. Our results extend those found in studies of spontaneous fluctuations in motor cortex and higher order visual areas, and suggest a fundamental role for spontaneous activity in stimulus processing. Copyright © 2011. Published by Elsevier Inc.
Reliability and validity of a simple and clinically applicable pain stimulus
DEFF Research Database (Denmark)
O'Neill, Søren; Graven-Nielsen, Thomas; Manniche, Claus
2014-01-01
and after conditioned pain modulation by cold-pressor test (CPT). Correlation to pressure pain threshold (PPT) of the infraspinatus muscle and cold-pressor test pain intensity, time to pain onset and time to non-tolerance, was examined. Test/re-test reliability of clamp pain was also assessed...... and the stimulus-response relationship was examined with a set of 6 different clamps.Conclusions: Clamp pain was sensitive to changes in pain sensitivity provoked by conditioned pain modulation (CPM). Test/re-test reliability of the spring-clamp pain was better for healthy volunteers over a period of days, than...
Motormouth: Mere Exposure Depends on Stimulus-Specific Motor Simulations
Topolinski, Sascha; Strack, Fritz
2009-01-01
The authors apply an embodied account to mere exposure, arguing that through the repeated exposure of a particular stimulus, motor responses specifically associated to that stimulus are repeatedly simulated, thus trained, and become increasingly fluent. This increased fluency drives preferences for repeated stimuli. This hypothesis was tested by…
[The P300 based brain-computer interface: effect of stimulus position in a stimulus train].
Ganin, I P; Shishkin, S L; Kochetova, A G; Kaplan, A Ia
2012-01-01
The P300 brain-computer interface (BCI) is currently the most efficient BCI. This interface is based on detection of the P300 wave of the brain potentials evoked when a symbol related to the intended input is highlighted. To increase operation speed of the P300 BCI, reduction of the number of stimuli repetitions is needed. This reduction leads to increase of the relative contribution to the input symbol detection from the reaction to the first target stimulus. It is known that the event-related potentials (ERP) to the first stimulus presentations can be different from the ERP to stimuli presented latter. In particular, the amplitude of responses to the first stimulus presentations is often increased, which is beneficial for their recognition by the BCI. However, this effect was not studied within the BCI framework. The current study examined the ERP obtained from healthy participants (n = 14) in the standard P300 BCI paradigm using 10 trials, as well as in the modified P300 BCI with stimuli presented on moving objects in triple-trial (n = 6) and single-trial (n = 6) stimulation modes. Increased ERP amplitude was observed in response to the first target stimuli in both conditions, as well as in the single-trial mode comparing to triple-trial. We discuss the prospects of using the specific features of the ERP to first stimuli and the single-trial ERP for optimizing the high-speed modes in the P300 BCIs.
Automatic detection of frequency changes depends on auditory stimulus intensity.
Salo, S; Lang, A H; Aaltonen, O; Lertola, K; Kärki, T
1999-06-01
A cortical cognitive auditory evoked potential, mismatch negativity (MMN), reflects automatic discrimination and echoic memory functions of the auditory system. For this study, we examined whether this potential is dependent on the stimulus intensity. The MMN potentials were recorded from 10 subjects with normal hearing using a sine tone of 1000 Hz as the standard stimulus and a sine tone of 1141 Hz as the deviant stimulus, with probabilities of 90% and 10%, respectively. The intensities were 40, 50, 60, 70, and 80 dB HL for both standard and deviant stimuli in separate blocks. Stimulus intensity had a statistically significant effect on the mean amplitude, rise time parameter, and onset latency of the MMN. Automatic auditory discrimination seems to be dependent on the sound pressure level of the stimuli.
International Nuclear Information System (INIS)
Zhang, Dingzong; Wang, Yanhui; Wang, Dezhen
2013-01-01
Period-doubling and chaos phenomenon have been frequently observed in atmospheric-pressure dielectric-barrier discharges. However, how a normal single period discharge bifurcates into period-doubling state is still unclear. In this paper, by changing the driving frequency, we study numerically the transition mechanisms from a normal single period discharge to a period-doubling state using a one-dimensional self-consistent fluid model. The results show that before a discharge bifurcates into a period-doubling state, it first deviates from its normal operation and transforms into an asymmetric single period discharge mode. Then the weaker discharge in this asymmetric discharge will be enhanced gradually with increasing of the frequency until it makes the subsequent discharge weaken and results in the discharge entering a period-doubling state. In the whole transition process, the spatial distribution of the charged particle density and the electric field plays a definitive role. The conclusions are further confirmed by changing the gap width and the amplitude of the applied voltage
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Zhang, Dingzong; Wang, Yanhui; Wang, Dezhen [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China)
2013-06-15
Period-doubling and chaos phenomenon have been frequently observed in atmospheric-pressure dielectric-barrier discharges. However, how a normal single period discharge bifurcates into period-doubling state is still unclear. In this paper, by changing the driving frequency, we study numerically the transition mechanisms from a normal single period discharge to a period-doubling state using a one-dimensional self-consistent fluid model. The results show that before a discharge bifurcates into a period-doubling state, it first deviates from its normal operation and transforms into an asymmetric single period discharge mode. Then the weaker discharge in this asymmetric discharge will be enhanced gradually with increasing of the frequency until it makes the subsequent discharge weaken and results in the discharge entering a period-doubling state. In the whole transition process, the spatial distribution of the charged particle density and the electric field plays a definitive role. The conclusions are further confirmed by changing the gap width and the amplitude of the applied voltage.
Performance breakdown in optimal stimulus decoding.
Lubomir Kostal; Lansky, Petr; Pilarski, Stevan
2015-06-01
One of the primary goals of neuroscience is to understand how neurons encode and process information about their environment. The problem is often approached indirectly by examining the degree to which the neuronal response reflects the stimulus feature of interest. In this context, the methods of signal estimation and detection theory provide the theoretical limits on the decoding accuracy with which the stimulus can be identified. The Cramér-Rao lower bound on the decoding precision is widely used, since it can be evaluated easily once the mathematical model of the stimulus-response relationship is determined. However, little is known about the behavior of different decoding schemes with respect to the bound if the neuronal population size is limited. We show that under broad conditions the optimal decoding displays a threshold-like shift in performance in dependence on the population size. The onset of the threshold determines a critical range where a small increment in size, signal-to-noise ratio or observation time yields a dramatic gain in the decoding precision. We demonstrate the existence of such threshold regions in early auditory and olfactory information coding. We discuss the origin of the threshold effect and its impact on the design of effective coding approaches in terms of relevant population size.
Retrospective Attention Interacts with Stimulus Strength to Shape Working Memory Performance.
Wildegger, Theresa; Humphreys, Glyn; Nobre, Anna C
2016-01-01
Orienting attention retrospectively to selective contents in working memory (WM) influences performance. A separate line of research has shown that stimulus strength shapes perceptual representations. There is little research on how stimulus strength during encoding shapes WM performance, and how effects of retrospective orienting might vary with changes in stimulus strength. We explore these questions in three experiments using a continuous-recall WM task. In Experiment 1 we show that benefits of cueing spatial attention retrospectively during WM maintenance (retrocueing) varies according to stimulus contrast during encoding. Retrocueing effects emerge for supraliminal but not sub-threshold stimuli. However, once stimuli are supraliminal, performance is no longer influenced by stimulus contrast. In Experiments 2 and 3 we used a mixture-model approach to examine how different sources of error in WM are affected by contrast and retrocueing. For high-contrast stimuli (Experiment 2), retrocues increased the precision of successfully remembered items. For low-contrast stimuli (Experiment 3), retrocues decreased the probability of mistaking a target with distracters. These results suggest that the processes by which retrospective attentional orienting shape WM performance are dependent on the quality of WM representations, which in turn depends on stimulus strength during encoding.
Rice, Nathaniel C; Makar, Jennifer R; Myers, Todd M
2017-03-15
The stimulus-movement effect refers to the phenomenon in which stimulus discrimination or acquisition of a response is facilitated by moving stimuli as opposed to stationary stimuli. The effect has been found in monkeys, rats, and humans, but the experiments conducted did not provide adequate female representation to investigate potential sex differences. The current experiment analyzed acquisition of stimulus touching in a progressive series of classical conditioning procedures in cynomolgus monkeys (Macaca fascicularis) as a function of sex and stimulus movement. Classical conditioning tasks arrange two or more stimuli in relation to each other with different temporal and predictive relations. Autoshaping procedures overlay operant contingencies onto a classical-conditioning stimulus arrangement. In the present case, a neutral stimulus (a small gray square displayed on a touchscreen) functioned as the conditional stimulus and a food pellet functioned as the unconditional stimulus. Although touching is not required to produce food, with repeated stimulus pairings subjects eventually touch the stimulus. Across conditions of increasing stimulus correlation and temporal contiguity, male monkeys acquired the response faster with a moving stimulus. In contrast, females acquired the response faster with a stationary stimulus. These results demonstrate that the stimulus-movement effect may be differentially affected by sex and indicate that additional experiments with females are needed to determine how sex interacts with behavioral phenomena discovered and elaborated almost exclusively using males. Published by Elsevier Inc.
Klein-Flügge, Miriam Cornelia; Barron, Helen Catharine; Brodersen, Kay Henning; Dolan, Raymond J; Behrens, Timothy Edward John
2013-02-13
A dominant focus in studies of learning and decision-making is the neural coding of scalar reward value. This emphasis ignores the fact that choices are strongly shaped by a rich representation of potential rewards. Here, using fMRI adaptation, we demonstrate that responses in the human orbitofrontal cortex (OFC) encode a representation of the specific type of food reward predicted by a visual cue. By controlling for value across rewards and by linking each reward with two distinct stimuli, we could test for representations of reward-identity that were independent of associative information. Our results show reward-identity representations in a medial-caudal region of OFC, independent of the associated predictive stimulus. This contrasts with a more rostro-lateral OFC region encoding reward-identity representations tied to the predicate stimulus. This demonstration of adaptation in OFC to reward specific representations opens an avenue for investigation of more complex decision mechanisms that are not immediately accessible in standard analyses, which focus on correlates of average activity.
How does reward compete with goal-directed and stimulus-driven shifts of attention?
Bourgeois, Alexia; Neveu, Rémi; Bayle, Dimitri J; Vuilleumier, Patrik
2017-01-01
In order to behave adaptively, attention can be directed in space either voluntarily (i.e. endogenously) according to strategic goals, or involuntarily (i.e. exogenously) through reflexive capture by salient or novel events. The emotional or motivational values of stimuli can also influence attentional orienting. However, little is known about how reward-related effects compete or interact with endogenous and exogenous attention mechanisms. Here we designed a visual search paradigm in which goal-driven and stimulus-driven shifts of attention were manipulated by classic spatial cueing procedures, while an irrelevant, but previously rewarded stimulus also appeared as a distractor and hence competed with both types of spatial attention during search. Our results demonstrated that stimuli previously associated with a high monetary reward received higher attentional priority in the subsequent visual search task, even though these stimuli and reward were no longer task-relevant, mitigating the attentional orienting induced by both endogenous and exogenous cues.
Furlong, T M; Pan, M J; Corbit, L H
2015-01-01
Alcohol-related stimuli can trigger relapse of alcohol-seeking behaviors even after extended periods of abstinence. Extinction of such stimuli can reduce their impact on relapse; however, the expression of extinction can be disrupted when testing occurs outside the context where extinction learning took place, an effect termed renewal. Behavioral and pharmacological methods have recently been shown to augment extinction learning; yet, it is not known whether the improved expression of extinction following these treatments remains context-dependent. Here we examined whether two methods, compound–stimulus extinction and treatment with the noradrenaline reuptake inhibitor atomoxetine, would reduce the vulnerability of extinction to a change in context. Following alcohol self-administration, responding was extinguished in a distinct context. After initial extinction, further extinction was given to a target stimulus presented in compound with another alcohol-predictive stimulus intended to augment prediction error (Experiment 1) or after a systemic injection of atomoxetine (1.0 mg kg−1; Experiment 2). A stimulus extinguished as part of a compound elicited less responding than a stimulus receiving equal extinction alone regardless of whether animals were tested in the training or extinction context; however, reliable renewal was not observed in this paradigm. Importantly, atomoxetine enhanced extinction relative to controls even in the presence of a reliable renewal effect. Thus, extinction of alcohol-seeking behavior can be improved by extinguishing multiple alcohol-predictive stimuli or enhancing noradrenaline neurotransmission during extinction training. Importantly, both methods improve extinction even when the context is changed between extinction training and test, and thus could be utilized to enhance the outcome of extinction-based treatments for alcohol-use disorders. PMID:26327688
Decoding stimulus features in primate somatosensory cortex during perceptual categorization
Alvarez, Manuel; Zainos, Antonio; Romo, Ranulfo
2015-01-01
Neurons of the primary somatosensory cortex (S1) respond as functions of frequency or amplitude of a vibrotactile stimulus. However, whether S1 neurons encode both frequency and amplitude of the vibrotactile stimulus or whether each sensory feature is encoded by separate populations of S1 neurons is not known, To further address these questions, we recorded S1 neurons while trained monkeys categorized only one sensory feature of the vibrotactile stimulus: frequency, amplitude, or duration. The results suggest a hierarchical encoding scheme in S1: from neurons that encode all sensory features of the vibrotactile stimulus to neurons that encode only one sensory feature. We hypothesize that the dynamic representation of each sensory feature in S1 might serve for further downstream processing that leads to the monkey’s psychophysical behavior observed in these tasks. PMID:25825711
Rudebeck, Peter H; Ripple, Joshua A; Mitz, Andrew R; Averbeck, Bruno B; Murray, Elisabeth A
2017-02-22
Orbitofrontal cortex (OFC), medial frontal cortex (MFC), and amygdala mediate stimulus-reward learning, but the mechanisms through which they interact are unclear. Here, we investigated how neurons in macaque OFC and MFC signaled rewards and the stimuli that predicted them during learning with and without amygdala input. Macaques performed a task that required them to evaluate two stimuli and then choose one to receive the reward associated with that option. Four main findings emerged. First, amygdala lesions slowed the acquisition and use of stimulus-reward associations. Further analyses indicated that this impairment was due, at least in part, to ineffective use of negative feedback to guide subsequent decisions. Second, the activity of neurons in OFC and MFC rapidly evolved to encode the amount of reward associated with each stimulus. Third, amygdalectomy reduced encoding of stimulus-reward associations during the evaluation of different stimuli. Reward encoding of anticipated and received reward after choices were made was not altered. Fourth, amygdala lesions led to an increase in the proportion of neurons in MFC, but not OFC, that encoded the instrumental response that monkeys made on each trial. These correlated changes in behavior and neural activity after amygdala lesions strongly suggest that the amygdala contributes to the ability to learn stimulus-reward associations rapidly by shaping encoding within OFC and MFC. SIGNIFICANCE STATEMENT Altered functional interactions among orbital frontal cortex (OFC), medial frontal cortex (MFC), and amygdala are thought to underlie several psychiatric conditions, many related to reward learning. Here, we investigated the causal contribution of the amygdala to the development of neuronal activity in macaque OFC and MFC related to rewards and the stimuli that predict them during learning. Without amygdala inputs, neurons in both OFC and MFC showed decreased encoding of stimulus-reward associations. MFC also showed
A Fundamental Study on Influence of Concurrently Presented Visual Stimulus Upon Loudness Perception
Directory of Open Access Journals (Sweden)
Koji Abe
2011-10-01
Full Text Available As a basic study on the influence of the dynamic properties of the audio-visual stimuli upon interaction between audition and vision, the effect of the simple movement involved in the visual stimulus on the loudness perception of the audio stimulus was investigated via psychophysical experiment. In this experiment, the visual stimulus given to subjects along with the audio stimulus is a bar appeared on a display, one side of which is flexibly expanding and contracting. The loudness of the audio stimulus with such a visual effect concurrently presented was rated as an absolute numerical value by using the Magnitude Estimation method. The reference of the bar length is determined so as to correspond to the Zwicker's loudness calculated for the given audio stimulus. As a result, the visual stimulus did not affect the loudness perception, when the bar was presented with its length same as the reference. On the other hand, the rating of the loudness for the same audio stimulus was significantly increased when the bar length was longer than the reference. This indicates that the change in the correspondence between the audio and the visual stimuli affect the loudness perception.
Modeling stimulus variation in three common implicit attitude tasks.
Wolsiefer, Katie; Westfall, Jacob; Judd, Charles M
2017-08-01
We explored the consequences of ignoring the sampling variation due to stimuli in the domain of implicit attitudes. A large literature in psycholinguistics has examined the statistical treatment of random stimulus materials, but the recommendations from this literature have not been applied to the social psychological literature on implicit attitudes. This is partly because of inherent complications in applying crossed random-effect models to some of the most common implicit attitude tasks, and partly because no work to date has demonstrated that random stimulus variation is in fact consequential in implicit attitude measurement. We addressed this problem by laying out statistically appropriate and practically feasible crossed random-effect models for three of the most commonly used implicit attitude measures-the Implicit Association Test, affect misattribution procedure, and evaluative priming task-and then applying these models to large datasets (average N = 3,206) that assess participants' implicit attitudes toward race, politics, and self-esteem. We showed that the test statistics from the traditional analyses are substantially (about 60 %) inflated relative to the more-appropriate analyses that incorporate stimulus variation. Because all three tasks used the same stimulus words and faces, we could also meaningfully compare the relative contributions of stimulus variation across the tasks. In an appendix, we give syntax in R, SAS, and SPSS for fitting the recommended crossed random-effects models to data from all three tasks, as well as instructions on how to structure the data file.
Retrospective Attention Interacts with Stimulus Strength to Shape Working Memory Performance.
Directory of Open Access Journals (Sweden)
Theresa Wildegger
Full Text Available Orienting attention retrospectively to selective contents in working memory (WM influences performance. A separate line of research has shown that stimulus strength shapes perceptual representations. There is little research on how stimulus strength during encoding shapes WM performance, and how effects of retrospective orienting might vary with changes in stimulus strength. We explore these questions in three experiments using a continuous-recall WM task. In Experiment 1 we show that benefits of cueing spatial attention retrospectively during WM maintenance (retrocueing varies according to stimulus contrast during encoding. Retrocueing effects emerge for supraliminal but not sub-threshold stimuli. However, once stimuli are supraliminal, performance is no longer influenced by stimulus contrast. In Experiments 2 and 3 we used a mixture-model approach to examine how different sources of error in WM are affected by contrast and retrocueing. For high-contrast stimuli (Experiment 2, retrocues increased the precision of successfully remembered items. For low-contrast stimuli (Experiment 3, retrocues decreased the probability of mistaking a target with distracters. These results suggest that the processes by which retrospective attentional orienting shape WM performance are dependent on the quality of WM representations, which in turn depends on stimulus strength during encoding.
Dinsmoor, James A.
1995-01-01
In his effort to distinguish operant from respondent conditioning, Skinner stressed the lack of an eliciting stimulus and rejected the prevailing stereotype of Pavlovian “stimulus—response” psychology. But control by antecedent stimuli, whether classified as conditional or discriminative, is ubiquitous in the natural setting. With both respondent and operant behavior, symmetrical gradients of generalization along unrelated dimensions may be obtained following differential reinforcement in the...
Stimulus Modality and Smoking Behavior: Moderating Role of Implicit Attitudes.
Ezeh, Valentine C; Mefoh, Philip
2015-07-20
This study investigated whether stimulus modality influences smoking behavior among smokers in South Eastern Nigeria and also whether implicit attitudes moderate the relationship between stimulus modality and smoking behavior. 60 undergraduate students of University of Nigeria, Nsukka were used. Participants were individually administered the IAT task as a measure of implicit attitude toward smoking and randomly assigned into either image condition that paired images of cigarette with aversive images of potential health consequences or text condition that paired images of cigarette with aversive texts of potential health consequences. A one- predictor and one-moderator binary logistic analysis indicates that stimulus modality significantly predicts smoking behavior (p = smoke with greater probability than the text condition. The interaction between stimulus modality and IAT scores was also significant (p = attitudes towards smoking. The finding shows the urgent need to introduce the use of aversive images of potential health consequences on cigarette packs in Nigeria.
Encoding efficiency of suprathreshold stochastic resonance on stimulus-specific information
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Duan, Fabing, E-mail: fabing.duan@gmail.com [Institute of Complexity Science, Qingdao University, Qingdao 266071 (China); Chapeau-Blondeau, François, E-mail: chapeau@univ-angers.fr [Laboratoire Angevin de Recherche en Ingénierie des Systèmes (LARIS), Université d' Angers, 62 avenue Notre Dame du Lac, 49000 Angers (France); Abbott, Derek, E-mail: derek.abbott@adelaide.edu.au [Centre for Biomedical Engineering (CBME) and School of Electrical & Electronic Engineering, The University of Adelaide, Adelaide, SA 5005 (Australia)
2016-01-08
In this paper, we evaluate the encoding efficiency of suprathreshold stochastic resonance (SSR) based on a local information-theoretic measure of stimulus-specific information (SSI), which is the average specific information of responses associated with a particular stimulus. The theoretical and numerical analyses of SSIs reveal that noise can improve neuronal coding efficiency for a large population of neurons, which leads to produce increased information-rich responses. The SSI measure, in contrast to the global measure of average mutual information, can characterize the noise benefits in finer detail for describing the enhancement of neuronal encoding efficiency of a particular stimulus, which may be of general utility in the design and implementation of a SSR coding scheme. - Highlights: • Evaluating the noise-enhanced encoding efficiency via stimulus-specific information. • New form of stochastic resonance based on the measure of encoding efficiency. • Analyzing neural encoding schemes from suprathreshold stochastic resonance detailedly.
Nav 1.8-null mice show stimulus-dependent deficits in spinal neuronal activity
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Wood John N
2006-02-01
Full Text Available Abstract Background The voltage gated sodium channel Nav 1.8 has a highly restricted expression pattern to predominantly nociceptive peripheral sensory neurones. Behaviourally Nav 1.8-null mice show an increased acute pain threshold to noxious mechanical pressure and also deficits in inflammatory and visceral, but not neuropathic pain. Here we have made in vivo electrophysiology recordings of dorsal horn neurones in intact anaesthetised Nav 1.8-null mice, in response to a wide range of stimuli to further the understanding of the functional roles of Nav 1.8 in pain transmission from the periphery to the spinal cord. Results Nav 1.8-null mice showed marked deficits in the coding by dorsal horn neurones to mechanical, but not thermal, -evoked responses over the non-noxious and noxious range compared to littermate controls. Additionally, responses evoked to other stimulus modalities were also significantly reduced in Nav 1.8-null mice where the reduction observed to pinch > brush. The occurrence of ongoing spontaneous neuronal activity was significantly less in mice lacking Nav 1.8 compared to control. No difference was observed between groups in the evoked activity to electrical activity of the peripheral receptive field. Conclusion This study demonstrates that deletion of the sodium channel Nav 1.8 results in stimulus-dependent deficits in the dorsal horn neuronal coding to mechanical, but not thermal stimuli applied to the neuronal peripheral receptive field. This implies that Nav 1.8 is either responsible for, or associated with proteins involved in mechanosensation.
International Nuclear Information System (INIS)
Li Hua; Ng, Teng Yong; Yew, Yong Kin
2009-01-01
Modeling is conducted in this paper for analysis of the influence of Young's modulus on the response of soft active hydrogels to environmental solution pH changes. A chemo–electro–mechanical formulation termed the multi-effect-coupling pH-stimulus (MECpH) model, which was developed previously according to linear elastic theory for small deformation description, is improved in this paper through incorporation of the finite deformation formulation into the mechanical equilibrium equation. The model is expressed by coupled nonlinear partial differential equations and solved via the meshless Hermite-cloud method with the modified Newton iteration technique. The improved MECpH model is examined by comparison between the computational and published experimental results. Numerical studies are then done on the influence of Young's modulus on the distributive variations of the diffusive ion concentrations and electric potential, and on the deformation variations of the pH-stimulus-responsive hydrogels within different buffered solutions
Vogel, Susanne; Klumpers, Floris; Schröder, Tobias Navarro; Oplaat, Krista T; Krugers, Harm J; Oitzl, Melly S; Joëls, Marian; Doeller, Christian F; Fernández, Guillén
2017-05-01
Stress is assumed to cause a shift from flexible 'cognitive' memory to more rigid 'habit' memory. In the spatial memory domain, stress impairs place learning depending on the hippocampus whereas stimulus-response learning based on the striatum appears to be improved. While the neural basis of this shift is still unclear, previous evidence in rodents points towards cortisol interacting with the mineralocorticoid receptor (MR) to affect amygdala functioning. The amygdala is in turn assumed to orchestrate the stress-induced shift in memory processing. However, an integrative study testing these mechanisms in humans is lacking. Therefore, we combined functional neuroimaging of a spatial memory task, stress-induction, and administration of an MR-antagonist in a full-factorial, randomized, placebo-controlled between-subjects design in 101 healthy males. We demonstrate that stress-induced increases in cortisol lead to enhanced stimulus-response learning, accompanied by increased amygdala activity and connectivity to the striatum. Importantly, this shift was prevented by an acute administration of the MR-antagonist spironolactone. Our findings support a model in which the MR and the amygdala play an important role in the stress-induced shift towards habit memory systems, revealing a fundamental mechanism of adaptively allocating neural resources that may have implications for stress-related mental disorders.
Nicotine as a discriminative stimulus for ethanol use.
Ginsburg, Brett C; Levy, Simon A; Lamb, R J
2018-01-01
Abused drugs reinforce behavior; i.e., they increase the probability of the behavior preceding their administration. Abused drugs can also act as discriminative stimuli; i.e., they can set the occasion for responding reinforced by another event. Thus, one abused drug could come to set the occasion for the use of another and this functional relationship may play a role in polysubstance abuse, where common patterns of use could result in this relationship. Here we establish nicotine (0.4mg/kg, ip 5-min pre-session) as a discriminative stimulus for behavior reinforced by ethanol (0.1ml 8% w/v po, versus food) and determine the ability of nicotine (0.02-0.4mg/kg), varenicline (0.1-3.0mg/kg), and ethanol (250 and 500mg/kg) to control responding for ethanol. We compare these results to those from rats where nicotine signaled food was available (and ethanol was not). Nicotine came to function as a discriminative stimulus. Nicotine and varenicline produced dose-dependent increases in responding on the nicotine-appropriate lever while ethanol produced responding on the vehicle-appropriate lever. Whether this responding occurred on the lever that produced ethanol or food access depended on the training condition. These results demonstrate that a drug can come to set the occasion for use of another and suggest that this behavioral mechanism could play an important role in the maintenance of and recovery from polysubstance abuse, depending on the pattern of use. Copyright © 2017 Elsevier B.V. All rights reserved.
Meijer, Guido T; Montijn, Jorrit S; Pennartz, Cyriel M A; Lansink, Carien S
2017-09-06
The sensory neocortex is a highly connected associative network that integrates information from multiple senses, even at the level of the primary sensory areas. Although a growing body of empirical evidence supports this view, the neural mechanisms of cross-modal integration in primary sensory areas, such as the primary visual cortex (V1), are still largely unknown. Using two-photon calcium imaging in awake mice, we show that the encoding of audiovisual stimuli in V1 neuronal populations is highly dependent on the features of the stimulus constituents. When the visual and auditory stimulus features were modulated at the same rate (i.e., temporally congruent), neurons responded with either an enhancement or suppression compared with unisensory visual stimuli, and their prevalence was balanced. Temporally incongruent tones or white-noise bursts included in audiovisual stimulus pairs resulted in predominant response suppression across the neuronal population. Visual contrast did not influence multisensory processing when the audiovisual stimulus pairs were congruent; however, when white-noise bursts were used, neurons generally showed response suppression when the visual stimulus contrast was high whereas this effect was absent when the visual contrast was low. Furthermore, a small fraction of V1 neurons, predominantly those located near the lateral border of V1, responded to sound alone. These results show that V1 is involved in the encoding of cross-modal interactions in a more versatile way than previously thought. SIGNIFICANCE STATEMENT The neural substrate of cross-modal integration is not limited to specialized cortical association areas but extends to primary sensory areas. Using two-photon imaging of large groups of neurons, we show that multisensory modulation of V1 populations is strongly determined by the individual and shared features of cross-modal stimulus constituents, such as contrast, frequency, congruency, and temporal structure. Congruent
Stimulus-dependent maximum entropy models of neural population codes.
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Einat Granot-Atedgi
Full Text Available Neural populations encode information about their stimulus in a collective fashion, by joint activity patterns of spiking and silence. A full account of this mapping from stimulus to neural activity is given by the conditional probability distribution over neural codewords given the sensory input. For large populations, direct sampling of these distributions is impossible, and so we must rely on constructing appropriate models. We show here that in a population of 100 retinal ganglion cells in the salamander retina responding to temporal white-noise stimuli, dependencies between cells play an important encoding role. We introduce the stimulus-dependent maximum entropy (SDME model-a minimal extension of the canonical linear-nonlinear model of a single neuron, to a pairwise-coupled neural population. We find that the SDME model gives a more accurate account of single cell responses and in particular significantly outperforms uncoupled models in reproducing the distributions of population codewords emitted in response to a stimulus. We show how the SDME model, in conjunction with static maximum entropy models of population vocabulary, can be used to estimate information-theoretic quantities like average surprise and information transmission in a neural population.
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Benedikt Zoefel
2017-05-01
Full Text Available All sensory systems need to continuously prioritize and select incoming stimuli in order to avoid overflow or interference, and provide a structure to the brain's input. However, the characteristics of this input differ across sensory systems; therefore, and as a direct consequence, each sensory system might have developed specialized strategies to cope with the continuous stream of incoming information. Neural oscillations are intimately connected with this selection process, as they can be used by the brain to rhythmically amplify or attenuate input and therefore represent an optimal tool for stimulus selection. In this paper, we focus on oscillatory processes for stimulus selection in the visual and auditory systems. We point out both commonalities and differences between the two systems and develop several hypotheses, inspired by recently published findings: (1 The rhythmic component in its input is crucial for the auditory, but not for the visual system. The alignment between oscillatory phase and rhythmic input (phase entrainment is therefore an integral part of stimulus selection in the auditory system whereas the visual system merely adjusts its phase to upcoming events, without the need for any rhythmic component. (2 When input is unpredictable, the visual system can maintain its oscillatory sampling, whereas the auditory system switches to a different, potentially internally oriented, “mode” of processing that might be characterized by alpha oscillations. (3 Visual alpha can be divided into a faster occipital alpha (10 Hz and a slower frontal alpha (7 Hz that critically depends on attention.
Pérez-Díaz, Francisco; Díaz, Estrella; Sánchez, Natividad; Vargas, Juan Pedro; Pearce, John M; López, Juan Carlos
2017-01-01
Recent studies support the idea that stimulus processing in latent inhibition can vary during the course of preexposure. Controlled attentional mechanisms are said to be important in the early stages of preexposure, while in later stages animals adopt automatic processing of the stimulus to be used for conditioning. Given this distinction, it is possible that both types of processing are governed by different neural systems, affecting differentially the retrieval of information about the stimulus. In the present study we tested if a lesion to the dorso-lateral striatum or to the medial prefrontal cortex has a selective effect on exposure to the future conditioned stimulus (CS). With this aim, animals received different amounts of exposure to the future CS. The results showed that a lesion to the medial prefrontal cortex enhanced latent inhibition in animals receiving limited preexposure to the CS, but had no effect in animals receiving extended preexposure to the CS. The lesion of the dorso-lateral striatum produced a decrease in latent inhibition, but only in animals with an extended exposure to the future conditioned stimulus. These results suggest that the dorsal striatum and medial prefrontal cortex play essential roles in controlled and automatic processes. Automatic attentional processes appear to be impaired by a lesion to the dorso-lateral striatum and facilitated by a lesion to the prefrontal cortex.
Javitt, D C; Steinschneider, M; Schroeder, C E; Vaughan, H G; Arezzo, J C
1994-12-26
Mismatch negativity (MMN) is a cognitive, auditory event-related potential (AEP) that reflects preattentive detection of stimulus deviance and indexes the operation of the auditory sensory ('echoic') memory system. MMN is elicited most commonly in an auditory oddball paradigm in which a sequence of repetitive standard stimuli is interrupted infrequently and unexpectedly by a physically deviant 'oddball' stimulus. Electro- and magnetoencephalographic dipole mapping studies have localized the generators of MMN to supratemporal auditory cortex in the vicinity of Heschl's gyrus, but have not determined the degree to which MMN reflects activation within primary auditory cortex (AI) itself. The present study, using moveable multichannel electrodes inserted acutely into superior temporal plane, demonstrates a significant contribution of AI to scalp-recorded MMN in the monkey, as reflected by greater response of AI to loud or soft clicks presented as deviants than to the same stimuli presented as repetitive standards. The MMN-like activity was localized primarily to supragranular laminae within AI. Thus, standard and deviant stimuli elicited similar degrees of initial, thalamocortical excitation. In contrast, responses within supragranular cortex were significantly larger to deviant stimuli than to standards. No MMN-like activity was detected in a limited number to passes that penetrated anterior and medial to AI. AI plays a well established role in the decoding of the acoustic properties of individual stimuli. The present study demonstrates that primary auditory cortex also plays an important role in processing the relationships between stimuli, and thus participates in cognitive, as well as purely sensory, processing of auditory information.
Besserve, Michel; Lowe, Scott C; Logothetis, Nikos K; Schölkopf, Bernhard; Panzeri, Stefano
2015-01-01
Distributed neural processing likely entails the capability of networks to reconfigure dynamically the directionality and strength of their functional connections. Yet, the neural mechanisms that may allow such dynamic routing of the information flow are not yet fully understood. We investigated the role of gamma band (50-80 Hz) oscillations in transient modulations of communication among neural populations by using measures of direction-specific causal information transfer. We found that the local phase of gamma-band rhythmic activity exerted a stimulus-modulated and spatially-asymmetric directed effect on the firing rate of spatially separated populations within the primary visual cortex. The relationships between gamma phases at different sites (phase shifts) could be described as a stimulus-modulated gamma-band wave propagating along the spatial directions with the largest information transfer. We observed transient stimulus-related changes in the spatial configuration of phases (compatible with changes in direction of gamma wave propagation) accompanied by a relative increase of the amount of information flowing along the instantaneous direction of the gamma wave. These effects were specific to the gamma-band and suggest that the time-varying relationships between gamma phases at different locations mark, and possibly causally mediate, the dynamic reconfiguration of functional connections.
Autoshaping with common and distinctive stimulus elements, compact and dispersed arrays.
Sperling, S E; Perkins, M E
1979-05-01
Four groups of pigeons were trained with a standard autoshaping procedure in which a brief fixed-duration interval always followed by a grain delivery alternated with a longer variable-duration interval never associated with grain delivery. One of two stimuli was always presented during each interval. One of them contained three black dots and a black star on a green background; the other contained four black dots on a green background. The four elements of each stimulus were arranged in a more compact array for two groups and in a more dispersed array for the other two groups. Which of the two stimuli preceded grain delivery was counterbalanced within each pair of groups. The speed of occurrence of the first autoshaped peck was not affected by whether the stimulus containing the distinctive star element preceded grain delivery, but autoshaping was faster when the stimulus arrays were compact than when they were dispersed. During 560 response-independent training trials that followed the first autoshaped peck, this pattern reversed; both discriminative control over responding and the relative frequency of pecking the stimulus that preceded grain delivery were greater for the two groups where this stimulus contained the discriminative element than for the two groups where it contained only common elements. During subsequent testing with stimuli containing only a single element each, the distinctive feature was responded to proportionately more often by the two groups for which it had been an element of the stimulus preceding grain delivery than by the two groups for which it had been an element of the stimulus complex that never was associated with grain delivery. These data add further support to the hypothesis that the initial occurrence of autoshaped responding and its subsequent maintenance are not affected by the same variables. They also suggest that automaintenance is as sensitive as response-dependent training to the presence or absence of a distinctive
Stimulus Sensitivity of a Spiking Neural Network Model
Chevallier, Julien
2018-02-01
Some recent papers relate the criticality of complex systems to their maximal capacity of information processing. In the present paper, we consider high dimensional point processes, known as age-dependent Hawkes processes, which have been used to model spiking neural networks. Using mean-field approximation, the response of the network to a stimulus is computed and we provide a notion of stimulus sensitivity. It appears that the maximal sensitivity is achieved in the sub-critical regime, yet almost critical for a range of biologically relevant parameters.
van Laarhoven, Thijs; Stekelenburg, Jeroen J; Vroomen, Jean
2017-04-15
A rare omission of a sound that is predictable by anticipatory visual information induces an early negative omission response (oN1) in the EEG during the period of silence where the sound was expected. It was previously suggested that the oN1 was primarily driven by the identity of the anticipated sound. Here, we examined the role of temporal prediction in conjunction with identity prediction of the anticipated sound in the evocation of the auditory oN1. With incongruent audiovisual stimuli (a video of a handclap that is consistently combined with the sound of a car horn) we demonstrate in Experiment 1 that a natural match in identity between the visual and auditory stimulus is not required for inducing the oN1, and that the perceptual system can adapt predictions to unnatural stimulus events. In Experiment 2 we varied either the auditory onset (relative to the visual onset) or the identity of the sound across trials in order to hamper temporal and identity predictions. Relative to the natural stimulus with correct auditory timing and matching audiovisual identity, the oN1 was abolished when either the timing or the identity of the sound could not be predicted reliably from the video. Our study demonstrates the flexibility of the perceptual system in predictive processing (Experiment 1) and also shows that precise predictions of timing and content are both essential elements for inducing an oN1 (Experiment 2). Copyright © 2017 Elsevier B.V. All rights reserved.
The wave attenuation mechanism of the periodic local resonant metamaterial
Chang, I.-Ling; Liang, Zhen-Xian; Kao, Hao-Wei; Chang, Shih-Hsiang; Yang, Chih-Ying
2018-01-01
This research discusses the wave propagation behavior and attenuation mechanism of the elastic metamaterial with locally resonant sub-structure. The dispersion relation of the single resonance system, i.e., periodic spring mass system with sub-structure, could be derived based on lattice dynamics and the band gap could be easily identified. The dynamically equivalent properties, i.e., mass and elastic property, of the single resonance system are derived and found to be frequency dependent. Negative effective properties are found in the vicinity of the local resonance. It is examined whether the band gap always coincides with the frequency range of negative effective properties. The wave attenuation mechanism and the characteristic dynamic behavior of the elastic metamaterial are also studied from the energy point of view. From the analysis, it is clarified that the coupled Bragg-resonance band gap is much wider than the narrow-banded local resonance and the corresponding effective material properties at band gap could be either positive or negative. However, the band gap is totally overlapping with the frequency range of negative effective properties for the metamaterial with band gap purely caused by local resonance. The presented analysis can be extended to other forms of elastic metamaterials involving periodic resonator structures.
Directory of Open Access Journals (Sweden)
Paul eMiller
2013-05-01
Full Text Available Randomly connected recurrent networks of excitatory groups of neurons can possess a multitude of attractor states. When the internal excitatory synapses of these networks are depressing, the attractor states can be destabilized with increasing input. This leads to an itinerancy, where with either repeated transient stimuli, or increasing duration of a single stimulus, the network activity advances through sequences of attractor states. We find that the resulting network state, which persists beyond stimulus offset, can encode the number of stimuli presented via a distributed representation of neural activity with non-monotonic tuning curves for most neurons. Increased duration of a single stimulus is encoded via different distributed representations, so unlike an integrator, the network distinguishes separate successive presentations of a short stimulus from a single presentation of a longer stimulus with equal total duration. Moreover, different amplitudes of stimulus cause new, distinct activity patterns, such that changes in stimulus number, duration and amplitude can be distinguished from each other. These properties of the network depend on dynamic depressing synapses, as they disappear if synapses are static. Thus short-term synaptic depression allows a network to store separately the different dynamic properties of a spatially constant stimulus.
Energy Technology Data Exchange (ETDEWEB)
Gao, Gongming [Department of Orthopedics, The Affiliated Changzhou No. 2 Hospital of Nanjing Medical University, Changzhou 213003 (China); Shen, Nan [Department of Clinical Pharmacy, The Affiliated Jiangyin Hospital of Southeast University Medical School, Jiangyin 214400 (China); Jiang, Xuefeng; Sun, Huiqing [Department of Orthopedics, The Affiliated Jiangyin Hospital of Southeast University Medical School, Jiangyin 214400 (China); Xu, Nanwei; Zhou, Dong [Department of Orthopedics, The Affiliated Changzhou No. 2 Hospital of Nanjing Medical University, Changzhou 213003 (China); Nong, Luming, E-mail: lumingnong@hotmail.com [Department of Orthopedics, The Affiliated Changzhou No. 2 Hospital of Nanjing Medical University, Changzhou 213003 (China); Ren, Kewei, E-mail: keweiren@hotmail.com [Department of Orthopedics, The Affiliated Jiangyin Hospital of Southeast University Medical School, Jiangyin 214400 (China)
2016-01-15
The mitogenic effects of periodic mechanical stress on nucleus pulpous cells have been studied extensively but the mechanisms whereby nucleus pulpous cells sense and respond to mechanical stimulation remain a matter of debate. We explored this question by performing cell culture experiments in our self-developed periodic stress field and perfusion culture system. Under periodic mechanical stress, rat nucleus pulpous cell proliferation was significantly increased (p < 0.05 for each) and was associated with increases in the phosphorylation and activation of EGFR, Rac1, and ERK1/2 (p < 0.05 for each). Pretreatment with the ERK1/2 selective inhibitor PD98059 reduced periodic mechanical stress-induced nucleus pulpous cell proliferation (p < 0.05 for each), while the activation levels of EGFR and Rac1 were not inhibited. Proliferation and phosphorylation of ERK1/2 were inhibited after pretreatment with the Rac1 inhibitor NSC23766 in nucleus pulpous cells in response to periodic mechanical stress (p < 0.05 for each), while the phosphorylation site of EGFR was not affected. Inhibition of EGFR activity with AG1478 abrogated nucleus pulpous cell proliferation (p < 0.05 for each) and attenuated Rac1 and ERK1/2 activation in nucleus pulpous cells subjected to periodic mechanical stress (p < 0.05 for each). These findings suggest that periodic mechanical stress promotes nucleus pulpous cell proliferation in part through the EGFR-Rac1-ERK1/2 signaling pathway, which links these three important signaling molecules into a mitogenic cascade. - Highlights: • The mechanism involved in nucleus pulpous cells to respond to mechanical stimuli. • Periodic mechanical stress can stimulate the phosphorylation of EGFR. • EGFR activates Rac1 and leads to rat nucleus pulpous cell proliferation. • EGFR and Rac1 activate ERK1/2 mitogenic signals in nucleus pulpous cells. • EGFR-Rac1-ERK1/2 is constitutes at least one critical signal transduction pathway.
International Nuclear Information System (INIS)
Gao, Gongming; Shen, Nan; Jiang, Xuefeng; Sun, Huiqing; Xu, Nanwei; Zhou, Dong; Nong, Luming; Ren, Kewei
2016-01-01
The mitogenic effects of periodic mechanical stress on nucleus pulpous cells have been studied extensively but the mechanisms whereby nucleus pulpous cells sense and respond to mechanical stimulation remain a matter of debate. We explored this question by performing cell culture experiments in our self-developed periodic stress field and perfusion culture system. Under periodic mechanical stress, rat nucleus pulpous cell proliferation was significantly increased (p < 0.05 for each) and was associated with increases in the phosphorylation and activation of EGFR, Rac1, and ERK1/2 (p < 0.05 for each). Pretreatment with the ERK1/2 selective inhibitor PD98059 reduced periodic mechanical stress-induced nucleus pulpous cell proliferation (p < 0.05 for each), while the activation levels of EGFR and Rac1 were not inhibited. Proliferation and phosphorylation of ERK1/2 were inhibited after pretreatment with the Rac1 inhibitor NSC23766 in nucleus pulpous cells in response to periodic mechanical stress (p < 0.05 for each), while the phosphorylation site of EGFR was not affected. Inhibition of EGFR activity with AG1478 abrogated nucleus pulpous cell proliferation (p < 0.05 for each) and attenuated Rac1 and ERK1/2 activation in nucleus pulpous cells subjected to periodic mechanical stress (p < 0.05 for each). These findings suggest that periodic mechanical stress promotes nucleus pulpous cell proliferation in part through the EGFR-Rac1-ERK1/2 signaling pathway, which links these three important signaling molecules into a mitogenic cascade. - Highlights: • The mechanism involved in nucleus pulpous cells to respond to mechanical stimuli. • Periodic mechanical stress can stimulate the phosphorylation of EGFR. • EGFR activates Rac1 and leads to rat nucleus pulpous cell proliferation. • EGFR and Rac1 activate ERK1/2 mitogenic signals in nucleus pulpous cells. • EGFR-Rac1-ERK1/2 is constitutes at least one critical signal transduction pathway.
Vinken, Kasper; Vogels, Rufin; Op de Beeck, Hans
2017-03-20
From an ecological point of view, it is generally suggested that the main goal of vision in rats and mice is navigation and (aerial) predator evasion [1-3]. The latter requires fast and accurate detection of a change in the visual environment. An outstanding question is whether there are mechanisms in the rodent visual system that would support and facilitate visual change detection. An experimental protocol frequently used to investigate change detection in humans is the oddball paradigm, in which a rare, unexpected stimulus is presented in a train of stimulus repetitions [4]. A popular "predictive coding" theory of cortical responses states that neural responses should decrease for expected sensory input and increase for unexpected input [5, 6]. Despite evidence for response suppression and enhancement in noninvasive scalp recordings in humans with this paradigm [7, 8], it has proven challenging to observe both phenomena in invasive action potential recordings in other animals [9-11]. During a visual oddball experiment, we recorded multi-unit spiking activity in rat primary visual cortex (V1) and latero-intermediate area (LI), which is a higher area of the rodent ventral visual stream. In rat V1, there was only evidence for response suppression related to stimulus-specific adaptation, and not for response enhancement. However, higher up in area LI, spiking activity showed clear surprise-based response enhancement in addition to stimulus-specific adaptation. These results show that neural responses along the rat ventral visual stream become increasingly sensitive to changes in the visual environment, suggesting a system specialized in the detection of unexpected events. Copyright © 2017 Elsevier Ltd. All rights reserved.
BAHAN AJAR MENULIS CERITA FABEL DENGAN STIMULUS FILM FINDING NEMO
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Lia Noviana Qostantia
2017-03-01
Full Text Available This research objectives were (1 describing instructional material of writing fable story using stimulus of finding nemo movie and (2 describing instructional material feasibility of writing fable story using stimulus of Finding Nemo movie that obtained from expert test and practitioner (teacher and student test. The developed instructional material was complementary book of writing fable story for students with material, language, and book display that adjusted with student’s needs. Those objectives could be made as guidance in developing the instructional material which including material content feasibility, language, and complementary book display aspect. Tujuan penelitian ini adalah (1 mengembangkan bahan ajar menulis cerita fabel dengan stimulus film finding nemo, (2 mendeskripsikan kelayakan bahan ajar menulis cerita fabel dengan stimulus film Finding Nemo yang diperoleh dari uji ahli, uji praktisi guru, dan siswa. Bahan ajar yang dikembangkan berupa buku pelengkap menulis cerita fabel untuk siswa dengan materi, bahasa, dan penyajian buku yang disesuaikan dengan kebutuhan siswa. Tujuan tersebut dapat dijadikan panduan dalam mengembangkan bahan ajar yang mencakup aspek kelayakan isi materi, bahasa, dan penyajian buku pelengkap.
Comparison on driving fatigue related hemodynamics activated by auditory and visual stimulus
Deng, Zishan; Gao, Yuan; Li, Ting
2018-02-01
As one of the main causes of traffic accidents, driving fatigue deserves researchers' attention and its detection and monitoring during long-term driving require a new technique to realize. Since functional near-infrared spectroscopy (fNIRS) can be applied to detect cerebral hemodynamic responses, we can promisingly expect its application in fatigue level detection. Here, we performed three different kinds of experiments on a driver and recorded his cerebral hemodynamic responses when driving for long hours utilizing our device based on fNIRS. Each experiment lasted for 7 hours and one of the three specific experimental tests, detecting the driver's response to sounds, traffic lights and direction signs respectively, was done every hour. The results showed that visual stimulus was easier to cause fatigue compared with auditory stimulus and visual stimulus induced by traffic lights scenes was easier to cause fatigue compared with visual stimulus induced by direction signs in the first few hours. We also found that fatigue related hemodynamics caused by auditory stimulus increased fastest, then traffic lights scenes, and direction signs scenes slowest. Our study successfully compared audio, visual color, and visual character stimulus in sensitivity to cause driving fatigue, which is meaningful for driving safety management.
Mass Media as a Remedy for Poverty of the Stimulus in the Foreign Language Context
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Samaneh Tarighat
2016-11-01
Full Text Available The present study is intended to determine how extensive exposure to target language mass media can affect foreign language learning and the poverty of the stimulus problem in the foreign language context. For this purpose, an EFL learner was studied for the period of one month and was asked to have extensive exposure to English language mass media only. The case was also asked to record her experience in a journal on a daily basis. The results indicated tangible improvement in her English speaking, listening, pronunciation and vocabulary but hardly any improvement on her English writing. A more profound impact was reported on the subject’s four-year-old son who was not initially the focus of this study. The results suggest that considering the authentic, lengthy language input it provides, foreign language mass media can compensate for the problem of poverty of the stimulus in foreign language learning. It is concluded that formal language instruction and exposure to foreign language mass media outside the class can complement one another and promote foreign language learning on the whole. It is also evident that the impact of extensive language input varies with the age of the language learner, with young learners bearing more influence than adult learners as the effects of the critical period hypothesis.
Ginsburg, Brett C.; Lamb, R. J.
2012-01-01
BACKGROUND Longer periods of recovery reduce the likelihood of relapse, which may be due to a reduced ability of various stimuli to occasion alcohol or drug seeking. However, this hypothesis remains largely uninvestigated. METHODS Here we assessed the ability of intermediate stimuli to occasion responding for ethanol in rats trained to discriminate an 8kHz tone signaling a food fixed-ratio (FR) of 5 and an ethanol FR5, from a 16kHz tone signaling a food FR150 and ethanol FR5. In the presence of the 8kHz tone responding for food predominates, and in the presence of the 16 kHz tone, responding for ethanol predominates. RESULTS In the context of alternation between these conditions, varying the tone from 8 to 16kHz produces a graded increase in ethanol (versus food) responding, consistent with a stimulus generalization function. A recent history of responding under food-predominant choice conditions, either during the test session or in the four sessions that precede it shifts the generalization function downwards. Extending this history to nine sessions shifts the curve further downwards. The stimulus generalization function was similar in a separate group, trained with different relative ratios for food and ethanol, but with similar behavioral allocation under each discriminative stimulus. Finally, withholding access to food and ethanol for 4 or 16 sessions did not affect the stimulus generalization gradient. CONCLUSION These results suggest that longer histories of reinforced alternative behavior might reduce the likelihood of relapse by decreasing the control exerted over alcohol- or drug-seeking by stimuli similar to those that previously occasioned alcohol- or drug-seeking. PMID:23122598
Kinetics and mechanism of oxidation of tellurium (IV) by periodate in alkaline medium
International Nuclear Information System (INIS)
Srinivas, K.; Vani, P.; Dikshitulu, L.S.A.
1995-01-01
Detailed kinetic study of the oxidation of tellurium (IV) by periodate in alkaline medium has been carried out to compare the mechanisms of oxidation in the acid and alkaline media. It is interesting to note that the rate step involves a two-electron transfer from tellurium (IV) to periodate in alkaline medium although the kinetic pattern is somewhat different from that in the acid medium. 7 refs., 1 tab
ASYMMETRIC EFFECTS OF ADDED VERSUS DELETED FEATURE OF STIMULUS ON RECOGNITION MEMORY
内野, 八潮; 箱田, 裕司
2000-01-01
This article reviewed a number of studies which revealed superiority of addition over deletion. Such an asymmetric effect was found in picture recognitioa memory, discrimination learning, proofreading for misspellings and so on. However, few studies have controlled typicality of original stimulus or the effect of addition and deletion on typicality of changed stimulus. Therefore this article focussed particularly on the studies in which addition and deletion applied to original stimulus was d...
Discrimination learning with variable stimulus 'salience'
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Treviño Mario
2011-08-01
Full Text Available Abstract Background In nature, sensory stimuli are organized in heterogeneous combinations. Salient items from these combinations 'stand-out' from their surroundings and determine what and how we learn. Yet, the relationship between varying stimulus salience and discrimination learning remains unclear. Presentation of the hypothesis A rigorous formulation of the problem of discrimination learning should account for varying salience effects. We hypothesize that structural variations in the environment where the conditioned stimulus (CS is embedded will be a significant determinant of learning rate and retention level. Testing the hypothesis Using numerical simulations, we show how a modified version of the Rescorla-Wagner model, an influential theory of associative learning, predicts relevant interactions between varying salience and discrimination learning. Implications of the hypothesis If supported by empirical data, our model will help to interpret critical experiments addressing the relations between attention, discrimination and learning.
Nikitin, V P; Kozyrev, S A; Solntseva, S V
2017-01-01
Specificity of behavioral and neuronal mechanisms of impairment of long-term memory reconsolidation was studied in edible snails trained for associative skill of rejection of two types of food: raw carrots (conditioned stimulus 1) and apple (conditioned stimulus 2). In 2 days after training, the snails received protein synthesis inhibitor cycloheximide and a reminder (conditioned stimulus 1 or 2). In 3 and 14 days after cycloheximide/reminder, we observed the absence of aversive responses to the conditioned stimulus used as the reminder and preserved responses to the conditioned stimulus not used as the reminder. Moreover, we observed specific suppression of synaptic responses of command neurons of snail defensive behavior induced by the conditioned stimulus used as the reminder after cycloheximide injection and preserved synaptic responses of neurons to the other conditioned stimulus. It was hypothesized that protein synthesis-dependent synapse-specific plasticity of command neurons can be a mechanism of selective preservation of conditioned food aversion memory in snails.
Reinforcing and discriminative stimulus properties of music in goldfish.
Shinozuka, Kazutaka; Ono, Haruka; Watanabe, Shigeru
2013-10-01
This paper investigated whether music has reinforcing and discriminative stimulus properties in goldfish. Experiment 1 examined the discriminative stimulus properties of music. The subjects were successfully trained to discriminate between two pieces of music--Toccata and Fugue in D minor (BWV 565) by J. S. Bach and The Rite of Spring by I. Stravinsky. Experiment 2 examined the reinforcing properties of sounds, including BWV 565 and The Rite of Spring. We developed an apparatus for measuring spontaneous sound preference in goldfish. Music or noise stimuli were presented depending on the subject's position in the aquarium, and the time spent in each area was measured. The results indicated that the goldfish did not show consistent preferences for music, although they showed significant avoidance of noise stimuli. These results suggest that music has discriminative but not reinforcing stimulus properties in goldfish. Copyright © 2013 Elsevier B.V. All rights reserved.
Do People Take Stimulus Correlations into Account in Visual Search (Open Source)
2016-03-10
RESEARCH ARTICLE Do People Take Stimulus Correlations into Account in Visual Search? Manisha Bhardwaj1, Ronald van den Berg2,3, Wei Ji Ma2,4...journal.pone.0149402 March 10, 2016 1 / 16 OPEN ACCESS Citation: Bhardwaj M, van den Berg R, Ma WJ, Josić K (2016) Do People Take Stimulus Correlations into...different values of ρ, larger set sizes, and more extensive training could shed more light on how exactly people misestimate stimulus correlations in
DEFF Research Database (Denmark)
Engdahl, Lis; Bjerre, Vicky K; Christoffersen, Gert R J
2007-01-01
Cognitive anticipation of a stimulus has been associated with an ERP called "stimulus preceding negativity" (SPN). A new auditory delay task without stimulus-related motor activity demonstrated a prefrontal SPN, present during attentive anticipation of sounds with closed eyes, but absent during d...
Phenomenology and Clinical Correlates of Stimulus-Bound Tics in Gilles de la Tourette Syndrome
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Piotr Janik
2018-06-01
Full Text Available Introduction: Stimulus-bound tics (SBTs belong to stimulus-induced behaviors and are defined as tics that occur in response to internal or external stimuli. The aim of the study was to assess the prevalence and associations of SBTs with other stimulus-triggered behaviors, premonitory urges and stimulus sensitization in Gilles de la Tourette syndrome (GTS.Methods: We performed a prospective, one-registration study in a cohort of 140 consecutive patients with GTS. Duration of GTS was 10.6 ± 8.7 years (range: 0–39 years. SBTs were diagnosed during the interview.Results: SBTs occurred at some point in the lifetime of 20.7% of patients. The presence of SBTs in adults was four times as frequent as in children (35.5% vs. 9.0% with the most frequent onset in adolescence (58.8% and adulthood (29.4%. These tics started 9.1 ± 4.7 years after the onset of tics. One stimulus and mental stimulus preceded tics most frequently, 44.8 and 33.3%, respectively. There was no established pattern of tics triggered by stimuli. Multivariate logistic regression analysis showed significant associations of SBTs with age at evaluation, tic severity, and palilalia but not with any co-morbid psychiatric disorders. 80% of patients showed at least one stimulus-triggered behavior. Premonitory urges and stimulus sensitization were reported by 60.0 and 40.7% of patients, respectively. No significant correlations between SBTs, premonitory urges and stimulus sensitization were found.Conclusion: SBTs are a part of the tic spectrum and should be taken into account by clinicians who deal with GTS patients. These tics fall at the tic end of the continuum of stimulus-induced behaviors.
Stimulus driver for epilepsy seizure suppression with adaptive loading impedance
Ker, Ming-Dou; Lin, Chun-Yu; Chen, Wei-Ling
2011-10-01
A stimulus driver circuit for a micro-stimulator used in an implantable device is presented in this paper. For epileptic seizure control, the target of the driver was to output 30 µA stimulus currents when the electrode impedance varied between 20 and 200 kΩ. The driver, which consisted of the output stage, control block and adaptor, was integrated in a single chip. The averaged power consumption of the stimulus driver was 0.24-0.56 mW at 800 Hz stimulation rate. Fabricated in a 0.35 µm 3.3 V/24 V CMOS process and applied to a closed-loop epileptic seizure monitoring and controlling system, the proposed design has been successfully verified in the experimental results of Long-Evans rats with epileptic seizures.
Heterogeneity of reward mechanisms.
Lajtha, A; Sershen, H
2010-06-01
The finding that many drugs that have abuse potential and other natural stimuli such as food or sexual activity cause similar chemical changes in the brain, an increase in extracellular dopamine (DA) in the shell of the nucleus accumbens (NAccS), indicated some time ago that the reward mechanism is at least very similar for all stimuli and that the mechanism is relatively simple. The presently available information shows that the mechanisms involved are more complex and have multiple elements. Multiple brain regions, multiple receptors, multiple distinct neurons, multiple transmitters, multiple transporters, circuits, peptides, proteins, metabolism of transmitters, and phosphorylation, all participate in reward mechanisms. The system is variable, is changed during development, is sex-dependent, and is influenced by genetic differences. Not all of the elements participate in the reward of all stimuli. Different set of mechanisms are involved in the reward of different drugs of abuse, yet different mechanisms in the reward of natural stimuli such as food or sexual activity; thus there are different systems that distinguish different stimuli. Separate functions of the reward system such as anticipation, evaluation, consummation and identification; all contain function-specific elements. The level of the stimulus also influences the participation of the elements of the reward system, there are possible reactions to even below threshold stimuli, and excessive stimuli can change reward to aversion involving parts of the system. Learning and memory of past reward is an important integral element of reward and addictive behavior. Many of the reward elements are altered by repeated or chronic stimuli, and chronic exposure to one drug is likely to alter the response to another stimulus. To evaluate and identify the reward stimulus thus requires heterogeneity of the reward components in the brain.
Mechanism design of reverse auction on concession period and generalized quality for PPP projects
Institute of Scientific and Technical Information of China (English)
Xianjia WANG; Shiwei WU
2017-01-01
Reverse auctions of PPP projects usually require the bid to specify several characteristics of quality and the concession period to be fulfilled.This paper sets up a summary function of generalized quality,which contributes to reducing the dimensions of information.Thus,the multidimensional reverse auction model of a PPP project can be replaced by a two-dimensional direct mechanism based on the concession period and the generalized quality.Based on the theory of the revelation principle,the feasibility conditions,equilibrium solution and generalized quality requirements of such a mechanism,considering the influence of a variable investment structure are described.Moreover,two feasible multidimensional reverse auctions for implementing such a direct mechanism:Adjusting the scoring function and establishing a special reverse auction rule are built.The analysis shows that in these types of reverse auctions,optimal allocation can be achieved,the social benefit under the incomplete information will be maximized,and the private sector with the highest integrated management level wins the bid.In such a direct mechanism,the investment and financial pressure of the public sector can be reduced.
Stimulus uncertainty enhances long-term potentiation-like plasticity in human motor cortex.
Sale, Martin V; Nydam, Abbey S; Mattingley, Jason B
2017-03-01
Plasticity can be induced in human cortex using paired associative stimulation (PAS), which repeatedly and predictably pairs a peripheral electrical stimulus with transcranial magnetic stimulation (TMS) to the contralateral motor region. Many studies have reported small or inconsistent effects of PAS. Given that uncertain stimuli can promote learning, the predictable nature of the stimulation in conventional PAS paradigms might serve to attenuate plasticity induction. Here, we introduced stimulus uncertainty into the PAS paradigm to investigate if it can boost plasticity induction. Across two experimental sessions, participants (n = 28) received a modified PAS paradigm consisting of a random combination of 90 paired stimuli and 90 unpaired (TMS-only) stimuli. Prior to each of these stimuli, participants also received an auditory cue which either reliably predicted whether the upcoming stimulus was paired or unpaired (no uncertainty condition) or did not predict the upcoming stimulus (maximum uncertainty condition). Motor evoked potentials (MEPs) evoked from abductor pollicis brevis (APB) muscle quantified cortical excitability before and after PAS. MEP amplitude increased significantly 15 min following PAS in the maximum uncertainty condition. There was no reliable change in MEP amplitude in the no uncertainty condition, nor between post-PAS MEP amplitudes across the two conditions. These results suggest that stimulus uncertainty may provide a novel means to enhance plasticity induction with the PAS paradigm in human motor cortex. To provide further support to the notion that stimulus uncertainty and prediction error promote plasticity, future studies should further explore the time course of these changes, and investigate what aspects of stimulus uncertainty are critical in boosting plasticity. Copyright © 2016 Elsevier Ltd. All rights reserved.
Autoshaping with common and distinctive stimulus elements, compact and dispersed arrays1
Sperling, Sally E.; Perkins, Mark E.
1979-01-01
Four groups of pigeons were trained with a standard autoshaping procedure in which a brief fixed-duration interval always followed by a grain delivery alternated with a longer variable-duration interval never associated with grain delivery. One of two stimuli was always presented during each interval. One of them contained three black dots and a black star on a green background; the other contained four black dots on a green background. The four elements of each stimulus were arranged in a more compact array for two groups and in a more dispersed array for the other two groups. Which of the two stimuli preceded grain delivery was counterbalanced within each pair of groups. The speed of occurrence of the first autoshaped peck was not affected by whether the stimulus containing the distinctive star element preceded grain delivery, but autoshaping was faster when the stimulus arrays were compact than when they were dispersed. During 560 response-independent training trials that followed the first autoshaped peck, this pattern reversed; both discriminative control over responding and the relative frequency of pecking the stimulus that preceded grain delivery were greater for the two groups where this stimulus contained the discriminative element than for the two groups where it contained only common elements. During subsequent testing with stimuli containing only a single element each, the distinctive feature was responded to proportionately more often by the two groups for which it had been an element of the stimulus preceding grain delivery than by the two groups for which it had been an element of the stimulus complex that never was associated with grain delivery. These data add further support to the hypothesis that the initial occurrence of autoshaped responding and its subsequent maintenance are not affected by the same variables. They also suggest that automaintenance is as sensitive as response-dependent training to the presence or absence of a distinctive
Priming makes a stimulus more salient
Theeuwes, J.; van der Burg, E.
2013-01-01
The present study used visual prior entry to determine which of two stimuli received attention first. Observers were asked to judge whether two test stimuli across a range of stimulus onset asynchronies (SOAs) were synchronized or not (simultaneity judgment task; SJ), or to report the temporal order
Stimulus conflict triggers behavioral avoidance.
Dignath, David; Eder, Andreas B
2015-12-01
According to a recent extension of the conflict-monitoring theory, conflict between two competing response tendencies is registered as an aversive event and triggers a motivation to avoid the source of conflict. In the present study, we tested this assumption. Over five experiments, we examined whether conflict is associated with an avoidance motivation and whether stimulus conflict or response conflict triggers an avoidance tendency. Participants first performed a color Stroop task. In a subsequent motivation test, participants responded to Stroop stimuli with approach- and avoidance-related lever movements. These results showed that Stroop-conflict stimuli increased the frequency of avoidance responses in a free-choice motivation test, and also increased the speed of avoidance relative to approach responses in a forced-choice test. High and low proportions of response conflict in the Stroop task had no effect on avoidance in the motivation test. Avoidance of conflict was, however, obtained even with new conflict stimuli that had not been presented before in a Stroop task, and when the Stroop task was replaced with an unrelated filler task. Taken together, these results suggest that stimulus conflict is sufficient to trigger avoidance.
Approach-Avoidance Training Effects Are Moderated by Awareness of Stimulus-Action Contingencies.
Van Dessel, Pieter; De Houwer, Jan; Gast, Anne
2016-01-01
Prior research suggests that repeatedly approaching or avoiding a stimulus changes the liking of that stimulus. In two experiments, we investigated the relationship between, on one hand, effects of approach-avoidance (AA) training on implicit and explicit evaluations of novel faces and, on the other hand, contingency awareness as indexed by participants' memory for the relation between stimulus and action. We observed stronger effects for faces that were classified as contingency aware and found no evidence that AA training caused changes in stimulus evaluations in the absence of contingency awareness. These findings challenge the standard view that AA training effects are (exclusively) the product of implicit learning processes, such as the automatic formation of associations in memory. © 2015 by the Society for Personality and Social Psychology, Inc.
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Lei Wang
2016-09-01
Full Text Available As the sole output neurons in the retina, ganglion cells play significant roles in transforming visual information into spike trains, and then transmitting them to the higher visual centers. However, coding strategies that retinal ganglion cells (RGCs adopt to accomplish these processes are not completely clear yet. To clarify these issues, we investigate the coding properties of three types of RGCs (repetitive spiking, tonic firing, and phasic firing by two different measures (spike-rate and spike-latency. Model results show that for periodic stimuli, repetitive spiking RGC and tonic RGC exhibit similar spike-rate patterns. Their spike-rates decrease gradually with increased stimulus frequency, moreover, variation of stimulus amplitude would change the two RGCs’ spike-rate patterns. For phasic RGC, it activates strongly at medium levels of frequency when the stimulus amplitude is low. While if high stimulus amplitude is applied, phasic RGC switches to respond strongly at low frequencies. These results suggest that stimulus amplitude is a prominent factor in regulating RGCs in encoding periodic signals. Similar conclusions can be drawn when analyzes spike-latency patterns of the three RGCs. More importantly, the above phenomena can be accurately reproduced by Hodgkin’s three classes of neurons, indicating that RGCs can perform the typical three classes of firing dynamics, depending on the distinctions of ion channel densities. Consequently, model results from the three RGCs may be not specific, but can also applicable to neurons in other brain regions which exhibit part(s or all of the Hodgkin’s three excitabilities.
Wang, Dong-Yuan Debbie; Richard, F Dan; Ray, Brittany
2016-01-01
The stimulus-response correspondence (SRC) effect refers to advantages in performance when stimulus and response correspond in dimensions or features, even if the common features are irrelevant to the task. Previous research indicated that the SRC effect depends on the temporal course of stimulus information processing. The current study investigated how the temporal overlap between relevant and irrelevant stimulus processing influences the SRC effect. In this experiment, the irrelevant stimulus (a previously associated tone) preceded the relevant stimulus (a coloured rectangle). The irrelevant and relevant stimuli onset asynchrony was varied to manipulate the temporal overlap between the irrelevant and relevant stimuli processing. Results indicated that the SRC effect size varied as a quadratic function of the temporal overlap between the relevant stimulus and irrelevant stimulus. This finding extends previous experimental observations that the SRC effect size varies in an increasing or decreasing function with reaction time. The current study demonstrated a quadratic function between effect size and the temporal overlap.
Rincover, Arnold; Ducharme, Joseph M.
1987-01-01
Three variables (diagnosis, location of cues, and mental age of learners) influencing stimulus control and stimulus overselectivity were assessed with eight autistic children (mean age 12 years) and eight average children matched for mean age. Among results were that autistic subjects tended to respond overselectively only in the extra-stimulus…
Comparing different stimulus configurations for population receptive field mapping in human fMRI
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Ivan eAlvarez
2015-02-01
Full Text Available Population receptive field (pRF mapping is a widely used approach to measuring aggregate human visual receptive field properties by recording non-invasive signals using functional MRI. Despite growing interest, no study to date has systematically investigated the effects of different stimulus configurations on pRF estimates from human visual cortex. Here we compared the effects of three different stimulus configurations on a model-based approach to pRF estimation: size-invariant bars and eccentricity-scaled bars defined in Cartesian coordinates and traveling along the cardinal axes, and a novel simultaneous ‘wedge and ring’ stimulus defined in polar coordinates, systematically covering polar and eccentricity axes. We found that the presence or absence of eccentricity scaling had a significant effect on goodness of fit and pRF size estimates. Further, variability in pRF size estimates was directly influenced by stimulus configuration, particularly for higher visual areas including V5/MT+. Finally, we compared eccentricity estimation between phase-encoded and model-based pRF approaches. We observed a tendency for more peripheral eccentricity estimates using phase-encoded methods, independent of stimulus size. We conclude that both eccentricity scaling and polar rather than Cartesian stimulus configuration are important considerations for optimal experimental design in pRF mapping. While all stimulus configurations produce adequate estimates, simultaneous wedge and ring stimulation produced higher fit reliability, with a significant advantage in reduced acquisition time.
Boddez, Yannick; Vervliet, Bram; Baeyens, Frank; Lauwers, Stephanie; Hermans, Dirk; Beckers, Tom
2012-06-01
In a blocking procedure, a single conditioned stimulus (CS) is paired with an unconditioned stimulus (US), such as electric shock, in the first stage. During the subsequent stage, the CS is presented together with a second CS and this compound is followed by the same US. Fear conditioning studies in non-human animals have demonstrated that fear responding to the added second CS typically remains low, despite its being paired with the US. Accordingly, the blocking procedure is well suited as a laboratory model for studying (deficits in) selective threat appraisal. The present study tested the relation between trait anxiety and blocking in human aversive conditioning. Healthy participants filled in a trait anxiety questionnaire and underwent blocking treatment in the human aversive conditioning paradigm. Threat appraisal was measured through shock expectancy ratings and skin conductance. As hypothesized, trait anxiety was positively associated with shock expectancy ratings to the blocked stimulus. In skin conductance responding, no significant effects of stimulus type could be detected during blocking training or testing. The current study does not allow strong claims to be made regarding the theoretical process underlying the expectancy bias we observed. The observed shock expectancy bias might be one of the mechanisms leading to non-specific fear in individuals at risk for developing anxiety disorders. A deficit in blocking, or a deficit in selective threat appraisal at the more general level, indeed results in fear becoming non-specific and disconnected from the most likely causes or predictors of danger. Copyright © 2011 Elsevier Ltd. All rights reserved.
Stimulus-driven capture and contingent capture
Theeuwes, J.; Olivers, C.N.L.; Belopolsky, A.V.
2010-01-01
Whether or not certain physical events can capture attention has been one of the most debated issues in the study of attention. This discussion is concerned with how goal-directed and stimulus-driven processes interact in perception and cognition. On one extreme of the spectrum is the idea that
Godin, Lindsay M; Suzuki, Sakiko; Jacobs, Christopher R; Donahue, Henry J; Donahue, Seth W
2007-11-01
An early response to mechanical stimulation of bone cells in vitro is an increase in intracellular calcium concentration ([Ca (2+)](i)). This study analyzed the [Ca (2+)](i) wave area, magnitude, duration, rise time, fall time, and time to onset in individual osteoblasts for two identical bouts of mechanical stimulation separated by a 30-min rest period. The area under the [Ca (2+)](i) wave increased in the second loading bout compared to the first. This suggests that rest periods may potentiate mechanically induced intracellular calcium signals. Furthermore, many of the [Ca (2+)](i) wave parameters were strongly, positively correlated between the two bouts of mechanical stimulation. For example, in individual primary osteoblasts, if a cell had a large [Ca (2+)](i) wave area in the first bout it was likely to have a large [Ca (2+)](i) wave area in the second bout (r (2) = 0.933). These findings support the idea that individual bone cells have "calcium fingerprints" (i.e., a unique [Ca (2+)](i) wave profile that is reproducible for repeated exposure to a given stimulus).
Decoupling Stimulus Duration from Brightness in Metacontrast Masking: Data and Models
Di Lollo, Vincent; Muhlenen, Adrian von; Enns, James T.; Bridgeman, Bruce
2004-01-01
A brief target that is visible when displayed alone can be rendered invisible by a trailing stimulus (metacontrast masking). It has been difficult to determine the temporal dynamics of masking to date because increments in stimulus duration have been invariably confounded with apparent brightness (Bloch's law). In the research reported here,…
Satou, Tsukasa; Ito, Misae; Shinomiya, Yuma; Takahashi, Yoshiaki; Hara, Naoto; Niida, Takahiro
2018-04-04
To investigate differences in the stimulus accommodative convergence/accommodation (AC/A) ratio using various techniques and accommodative stimuli, and to describe a method for determining the stimulus AC/A ratio. A total of 81 subjects with a mean age of 21 years (range, 20-23 years) were enrolled. The relationship between ocular deviation and accommodation was assessed using two methods. Ocular deviation was measured by varying the accommodative requirement using spherical plus/minus lenses to create an accommodative stimulus of 10.00 diopters (D) (in 1.00 D steps). Ocular deviation was assessed using the alternate prism cover test in method 1 at distance (5 m) and near (1/3 m), and the major amblyoscope in method 2. The stimulus AC/A ratios obtained using methods 1 and 2 were calculated and defined as the stimulus AC/A ratios with low and high accommodation, respectively, using the following analysis method. The former was calculated as the difference between the convergence response to an accommodative stimulus of 3 D and 0 D, divided by 3. The latter was calculated as the difference between the convergence response to a maximum (max) accommodative stimulus with distinct vision of the subject and an accommodative stimulus of max minus 3.00 D, divided by 3. The median stimulus AC/A ratio with low accommodation (1.0 Δ/D for method 1 at distance, 2.0 Δ/D for method 1 at near, and 2.7 Δ/D for method 2) differed significantly among the measurement methods (P accommodation (4.0 Δ/D for method 1 at distance, 3.7 Δ/D for method 1 at near, and 4.7 Δ/D for method 2) between method 1 at distance and method 2 were statistically significant (P accommodative stimuli. However, differences caused by measurement technique may be reduced by using a high accommodative stimulus during measurements.
Katus, Tobias; Eimer, Martin
2015-04-29
The short-term retention of sensory information in working memory (WM) is known to be associated with a sustained enhancement of neural activity. What remains controversial is whether this neural trace indicates the sustained storage of information or the allocation of attention. To evaluate the storage and attention accounts, we examined sustained tactile contralateral delay activity (tCDA component) of the event-related potential. The tCDA manifests over somatosensory cortex contralateral to task-relevant tactile information during stimulus retention. Two tactile sample sets (S1, S2) were presented sequentially, separated by 1.5 s. Each set comprised two stimuli, one per hand. Human participants memorized the location of one task-relevant stimulus per sample set and judged whether one of these locations was stimulated again at memory test. The two relevant pulses were unpredictably located on the same hand (stay trials) or on different hands (shift trials). Initially, tCDA components emerged contralateral to the relevant S1 pulse. Sequential loading of WM enhanced the tCDA after S2 was presented on stay trials. On shift trials, the tCDA's polarity reversed after S2 presentation, resulting in delay activity that was now contralateral to the task-relevant S2 pulse. The disappearance of a lateralized neural trace for the relevant S1 pulse did not impair memory accuracy for this stimulus on shift trials. These results contradict the storage account and suggest that delay period activity indicates the sustained engagement of an attention-based rehearsal mechanism. In conclusion, somatosensory delay period activity marks the current focus of attention in tactile WM. Copyright © 2015 the authors 0270-6474/15/356689-07$15.00/0.
Dynamic integration of reward and stimulus information in perceptual decision-making.
Gao, Juan; Tortell, Rebecca; McClelland, James L
2011-03-03
In perceptual decision-making, ideal decision-makers should bias their choices toward alternatives associated with larger rewards, and the extent of the bias should decrease as stimulus sensitivity increases. When responses must be made at different times after stimulus onset, stimulus sensitivity grows with time from zero to a final asymptotic level. Are decision makers able to produce responses that are more biased if they are made soon after stimulus onset, but less biased if they are made after more evidence has been accumulated? If so, how close to optimal can they come in doing this, and how might their performance be achieved mechanistically? We report an experiment in which the payoff for each alternative is indicated before stimulus onset. Processing time is controlled by a "go" cue occurring at different times post stimulus onset, requiring a response within msec. Reward bias does start high when processing time is short and decreases as sensitivity increases, leveling off at a non-zero value. However, the degree of bias is sub-optimal for shorter processing times. We present a mechanistic account of participants' performance within the framework of the leaky competing accumulator model [1], in which accumulators for each alternative accumulate noisy information subject to leakage and mutual inhibition. The leveling off of accuracy is attributed to mutual inhibition between the accumulators, allowing the accumulator that gathers the most evidence early in a trial to suppress the alternative. Three ways reward might affect decision making in this framework are considered. One of the three, in which reward affects the starting point of the evidence accumulation process, is consistent with the qualitative pattern of the observed reward bias effect, while the other two are not. Incorporating this assumption into the leaky competing accumulator model, we are able to provide close quantitative fits to individual participant data.
Varieties of Stimulus Control in Matching-to-Sample: A Kernel Analysis
Fields, Lanny; Garruto, Michelle; Watanabe, Mari
2010-01-01
Conditional discrimination or matching-to-sample procedures have been used to study a wide range of complex psychological phenomena with infrahuman and human subjects. In most studies, the percentage of trials in which a subject selects the comparison stimulus that is related to the sample stimulus is used to index the control exerted by the…
Directory of Open Access Journals (Sweden)
Tianyi Wang
2016-06-01
Full Text Available Stimulus-responsive microporous solid thin films were successfully fabricated by simple molecular self-assembly via an amphiphilic block polymer, polystryene–b–polyacrylic acid (PS–b–PAA. The solid thin films exhibit different surface morphologies in response to external stimuli, such as environments with different pH values in aqueous solutions. The experiments have successfully applied atomic force microscope (AFM technology to observe in-situ surface morphological changes. There is a reversible evolution of the microstructures in buffer solutions over a pH range of 2.4–9.2. These observations have been explained by positing that there is no conventional PAA swelling but that the PAA chains in the micropores stretch and contract with changes in the pH of the solution environment. The hydrophobicity of the solid thin film surface was transformed into super-hydrophilicity, as captured by optical contact angle measurements. The stimulus-responsive dynamics of pore sizes was described by a two-stage mechanism. A promising electrochemical application of this film is suggested via combination with an electrochemical impedance technique. This study is aimed at strategies for the functionalization of stimulus-responsive microporous solid thin films with reversible tunable surface morphologies, and exploring new smart materials with switch-on/switch-off behavior.
Stimulus fear-relevance and the vicarious learning pathway to childhood fears.
Askew, Chris; Dunne, Güler; Özdil, Zehra; Reynolds, Gemma; Field, Andy P
2013-10-01
Enhanced fear learning for fear-relevant stimuli has been demonstrated in procedures with adults in the laboratory. Three experiments investigated the effect of stimulus fear-relevance on vicarious fear learning in children (aged 6-11 years). Pictures of stimuli with different levels of fear-relevance (flowers, caterpillars, snakes, worms, and Australian marsupials) were presented alone or together with scared faces. In line with previous studies, children's fear beliefs and avoidance preferences increased for stimuli they had seen with scared faces. However, in contrast to evidence with adults, learning was mostly similar for all stimulus types irrespective of fear-relevance. The results support a proposal that stimulus preparedness is bypassed when children observationally learn threat-related information from adults.
The Poverty of the Mayan Stimulus
Pye, Clifton
2012-01-01
Poverty of the stimulus (POS) arguments have instigated considerable debate in the recent linguistics literature. This article uses the comparative method to challenge the logic of POS arguments. Rather than question the premises of POS arguments, the article demonstrates how POS arguments for individual languages lead to a "reductio ad absurdum"…
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Britt eAnderson
2015-03-01
Full Text Available Drawing on theoretical and computational work with the localist Dual Route reading model and results from behavioral studies, Besner, Moroz, and O'Malley (2011 proposed that the ability to perform tasks that require overriding stimulus-specific defaults (e.g., semantics when naming Arabic numerals, and phonology when evaluating the parity of number words necessitate the ability to modulate the strength of connections between cognitive modules for lexical representation, semantics, and phonology on a task- and stimulus-specific basis. We used fMRI to evaluate this account by assessing changes in functional connectivity while participants performed tasks that did and did not require such stimulus-task default overrides. The occipital region showing the greatest modulation of BOLD signal strength for the two stimulus types was used as the seed region for Granger Causality Mapping (GCM. Our GCM analysis revealed a region of rostromedial frontal cortex with a crossover interaction. When participants performed tasks that required overriding stimulus type defaults (i.e., parity judgments of number words and naming Arabic numerals functional connectivity between the occipital region and rostromedial frontal cortex was present. Statistically significant functional connectivity was absent when the tasks were the default for the stimulus type (i.e., parity judgments of Arabic numerals and reading number words. This frontal region (BA 10 has previously been shown to be involved in goal-directed behaviour and maintenance of a specific task-set. We conclude that overriding stimulus-task defaults requires a modulation of connection strengths between cognitive modules and that the override mechanism predicted from cognitive theory is instantiated by frontal modulation of neural activity of brain regions specialized for sensory processing.
van der Aa, Jeroen; Honing, Henkjan; ten Cate, Carel
2015-06-01
Perceiving temporal regularity in an auditory stimulus is considered one of the basic features of musicality. Here we examine whether zebra finches can detect regularity in an isochronous stimulus. Using a go/no go paradigm we show that zebra finches are able to distinguish between an isochronous and an irregular stimulus. However, when the tempo of the isochronous stimulus is changed, it is no longer treated as similar to the training stimulus. Training with three isochronous and three irregular stimuli did not result in improvement of the generalization. In contrast, humans, exposed to the same stimuli, readily generalized across tempo changes. Our results suggest that zebra finches distinguish the different stimuli by learning specific local temporal features of each individual stimulus rather than attending to the global structure of the stimuli, i.e., to the temporal regularity. Copyright © 2015 Elsevier B.V. All rights reserved.
Measuring consciousness: Task accuracy and awareness as sigmoid functions of stimulus duration
DEFF Research Database (Denmark)
Sandberg, Kristian; Bibby, Bo Martin; Timmermans, B
2011-01-01
certain limitations. In the present article, we propose describing task accuracy and awareness as functions of stimulus intensity (thus obtaining an accuracy and an awareness curve) as suggested by Koch and Preuschoff (2007). The estimated lag between the curves describes how much stimulus intensity must...
One for all: The effect of extinction stimulus typicality on return of fear.
Scheveneels, Sara; Boddez, Yannick; Bennett, Marc Patrick; Hermans, Dirk
2017-12-01
During exposure therapy, patients are encouraged to approach the feared stimulus, so they can experience that this stimulus is not followed by the anticipated aversive outcome. However, patients might treat the absence of the aversive outcome as an 'exception to the rule'. This could hamper the generalization of fear reduction when the patient is confronted with similar stimuli not used in therapy. We examined the effect of providing information about the typicality of the extinction stimulus on the generalization of extinction to a new but similar stimulus. In a differential fear conditioning procedure, an animal-like figure was paired with a brief electric shock to the wrist. In a subsequent extinction phase, a different but perceptually similar animal-like figure was presented without the shock. Before testing the generalization of extinction with a third animal-like figure, participants were either instructed that the extinction stimulus was a typical or an atypical member of the animal family. The typicality instruction effectively impacted the generalization of extinction; the third animal-like figure elicited lower shock expectancies in the typical relative to the atypical group. Skin conductance data mirrored these results, but did not reach significance. These findings suggest that verbal information about stimulus typicality can be a promising adjunctive to standard exposure treatments. Copyright © 2017 Elsevier Ltd. All rights reserved.
ERP Indices of Stimulus Prediction in Letter Sequences
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Edith Kaan
2014-10-01
Full Text Available Given the current focus on anticipation in perception, action and cognition, including language processing, there is a need for a method to tap into predictive processing in situations in which cue and feedback stimuli are not explicitly marked as such. To this aim, event related potentials (ERPs were obtained while participants viewed alphabetic letter sequences (“A”, “B”, “C”, “D”, “E”, …, in which the letters were highly predictable, and random sequences (“S”, “B”, “A”, “I”, “F”, “M”, …, without feedback. Occasionally, the presentation of a letter in a sequence was delayed by 300 ms. During this delay period, an increased negativity was observed for predictive versus random sequences. In addition, the early positivity following the delay was larger for predictive compared with random sequences. These results suggest that expectation-sensitive ERP modulations can be elicited in anticipation of stimuli that are not explicit targets, rewards, feedback or instructions, and that a delay can strengthen the prediction for a particular stimulus. Applications to language processing will be discussed.
Discriminative stimulus effects of alpidem, a new imidazopyridine anxiolytic.
Sanger, D J; Zivkovic, B
1994-01-01
Alpidem in an imidazopyridine derivative which binds selectively to the omega 1 (BZ1) receptor subtype. It is active in some, but not all, behavioural tests sensitive to benzodiazepine anxiolytics and has clinical anti-anxiety effects. However, in a previous study, it was shown that alpidem did not substitute for chlordiazepoxide in rats trained to discriminate this benzodiazepine. The present experiments were carried out to investigate the discriminative stimulus properties of alpidem in greater detail. In the first experiment rats learned to discriminate a dose of 10 mg/kg alpidem from saline. Acquisition of the discrimination was long and performance unstable. Chlordiazepoxide, clorazepate and zolpidem substituted only partially for alpidem but the effects of the training dose of alpidem were blocked by 10 mg/kg flumazenil. The second experiment established stimulus control more rapidly to a dose of 30 mg/kg alpidem. Alpidem induced dose-related stimulus control, and dose-related and complete substitution for alpidem was produced by zolpidem, abecarnil, CL 218,872, triazolam and suriclone. Partial substitution occurred with chlordiazepoxide, clorazepate and pentobarbital. In most cases, high levels of substitution were produced only by doses which greatly reduced response rates even though the training dose of alpidem produced only modest decreases in rates. Ethanol, buspirone and bretazenil produced very little substitution for alpidem and both flumazenil and bretazenil antagonised the effects of alpidem. In two further experiments alpidem was found to substitute for the stimulus produced by zolpidem (2 mg/kg) but not for that produced by ethanol (1.5 g/kg).(ABSTRACT TRUNCATED AT 250 WORDS)
MicroRNA-21 preserves the fibrotic mechanical memory of mesenchymal stem cells.
Li, Chen Xi; Talele, Nilesh P; Boo, Stellar; Koehler, Anne; Knee-Walden, Ericka; Balestrini, Jenna L; Speight, Pam; Kapus, Andras; Hinz, Boris
2017-03-01
Expansion on stiff culture substrates activates pro-fibrotic cell programs that are retained by mechanical memory. Here, we show that priming on physiologically soft silicone substrates suppresses fibrogenesis and desensitizes mesenchymal stem cells (MSCs) against subsequent mechanical activation in vitro and in vivo, and identify the microRNA miR-21 as a long-term memory keeper of the fibrogenic program in MSCs. During stiff priming, miR-21 levels were gradually increased by continued regulation through the acutely mechanosensitive myocardin-related transcription factor-A (MRTF-A/MLK-1) and remained high over 2 weeks after removal of the mechanical stimulus. Knocking down miR-21 once by the end of the stiff-priming period was sufficient to erase the mechanical memory and sensitize MSCs to subsequent exposure to soft substrates. Soft priming and erasing mechanical memory following cell culture expansion protects MSCs from fibrogenesis in the host wound environment and increases the chances for success of MSC therapy in tissue-repair applications.
Dye, J
1987-08-01
1. Weakly electric fish generate around their bodies low-amplitude, AC electric fields which are used both for the detection of objects and intraspecific communication. The types of modulation in this signal of which the high-frequency wave-type gymnotiform, Apteronotus, is capable are relatively few and stereotyped. Chief among these is the chirp, a signal used in courtship and agonistic displays. Chirps are brief and rapid accelerations in the normally highly regular electric organ discharge (EOD) frequency. 2. Chirping can be elicited artificially in these animals by the use of a stimulus regime identical to that typically used to elicit another behavior, the jamming avoidance response (JAR). The neuronal basis for the JAR, a much slower and lesser alteration in EOD frequency, is well understood. Examination of the stimulus features which induce chirping show that, like the JAR, there is a region of frequency differences between the fish's EOD and the interfering signal that maximally elicits the response. Moreover, the response is sex-specific with regard to the sign of the frequency difference, with females chirping preferentially on the positive and most males on the negative Df. These features imply that the sensory mechanisms involved in the triggering of these communicatory behaviors are fundamentally similar to those explicated for the JAR. 3. Additionally, two other modulatory behaviors of unknown significance are described. The first is a non-selective rise in EOD frequency associated with a JAR stimulus, occurring regardless of the sign of the Df. This modulation shares many characteristics with the JAR. The second behavior, which we have termed a 'yodel', is distinct from and kinetically intermediate to chirping and the JAR. Moreover, unlike the other studied electromotor behaviors it is generally produced only after the termination of the eliciting stimulus.
BOLDSync: a MATLAB-based toolbox for synchronized stimulus presentation in functional MRI.
Joshi, Jitesh; Saharan, Sumiti; Mandal, Pravat K
2014-02-15
Precise and synchronized presentation of paradigm stimuli in functional magnetic resonance imaging (fMRI) is central to obtaining accurate information about brain regions involved in a specific task. In this manuscript, we present a new MATLAB-based toolbox, BOLDSync, for synchronized stimulus presentation in fMRI. BOLDSync provides a user friendly platform for design and presentation of visual, audio, as well as multimodal audio-visual (AV) stimuli in functional imaging experiments. We present simulation experiments that demonstrate the millisecond synchronization accuracy of BOLDSync, and also illustrate the functionalities of BOLDSync through application to an AV fMRI study. BOLDSync gains an advantage over other available proprietary and open-source toolboxes by offering a user friendly and accessible interface that affords both precision in stimulus presentation and versatility across various types of stimulus designs and system setups. BOLDSync is a reliable, efficient, and versatile solution for synchronized stimulus presentation in fMRI study. Copyright © 2013 Elsevier B.V. All rights reserved.
Gibson, William T; Gonzalez, Carlos R; Fernandez, Conchi; Ramasamy, Lakshminarayanan; Tabachnik, Tanya; Du, Rebecca R; Felsen, Panna D; Maire, Michael R; Perona, Pietro; Anderson, David J
2015-06-01
The neural circuit mechanisms underlying emotion states remain poorly understood. Drosophila offers powerful genetic approaches for dissecting neural circuit function, but whether flies exhibit emotion-like behaviors has not been clear. We recently proposed that model organisms may express internal states displaying "emotion primitives," which are general characteristics common to different emotions, rather than specific anthropomorphic emotions such as "fear" or "anxiety." These emotion primitives include scalability, persistence, valence, and generalization to multiple contexts. Here, we have applied this approach to determine whether flies' defensive responses to moving overhead translational stimuli ("shadows") are purely reflexive or may express underlying emotion states. We describe a new behavioral assay in which flies confined in an enclosed arena are repeatedly exposed to an overhead translational stimulus. Repetitive stimuli promoted graded (scalable) and persistent increases in locomotor velocity and hopping, and occasional freezing. The stimulus also dispersed feeding flies from a food resource, suggesting both negative valence and context generalization. Strikingly, there was a significant delay before the flies returned to the food following stimulus-induced dispersal, suggestive of a slowly decaying internal defensive state. The length of this delay was increased when more stimuli were delivered for initial dispersal. These responses can be mathematically modeled by assuming an internal state that behaves as a leaky integrator of stimulus exposure. Our results suggest that flies' responses to repetitive visual threat stimuli express an internal state exhibiting canonical emotion primitives, possibly analogous to fear in mammals. The mechanistic basis of this state can now be investigated in a genetically tractable insect species. Copyright © 2015 Elsevier Ltd. All rights reserved.
Stimulus Predifferentiation and Modification of Children's Racial Attitudes
Katz, Phyllis A.
1973-01-01
The most significant finding is that stimulus-predifferentiation training elicited lower prejudice scores for children on two indices of ethnic attitudes than did a no-label control condition. (Author)
Aural, visual, and pictorial stimulus formats in false recall.
Beauchamp, Heather M
2002-12-01
The present investigation is an initial simultaneous examination of the influence of three stimulus formats on false memories. Several pilot tests were conducted to develop new category associate stimulus lists. 73 women and 26 men (M age=21.1 yr.) were in one of three conditions: they either heard words, were shown words, or were shown pictures highly related to critical nonpresented items. As expected, recall of critical nonpresented stimuli was significantly greater for aural lists than for visually presented words and pictorial images. These findings demonstrate that the accuracy of memory is influenced by the format of the information encoded.
DEFF Research Database (Denmark)
Overgaard, Morten; Lindeløv, Jonas Kristoffer; Svejstrup, Stinna
2013-01-01
This paper reports an experiment intended to test a particular hypothesis derived from blindsight research, which we name the “source misidentification hypothesis.” According to this hypothesis, a subject may be correct about a stimulus without being correct about how she had access...... to this knowledge (whether the stimulus was visual, auditory, or something else). We test this hypothesis in healthy subjects, asking them to report whether a masked stimulus was presented auditorily or visually, what the stimulus was, and how clearly they experienced the stimulus using the Perceptual Awareness...... experience of the stimulus. To demonstrate that particular levels of reporting accuracy are obtained, we employ a statistical strategy, which operationally tests the hypothesis of non-equality, such that the usual rejection of the null-hypothesis admits the conclusion of equivalence....
Stimulus induced bursts in severe postanoxic encephalopathy.
Tjepkema-Cloostermans, Marleen C; Wijers, Elisabeth T; van Putten, Michel J A M
2016-11-01
To report on a distinct effect of auditory and sensory stimuli on the EEG in comatose patients with severe postanoxic encephalopathy. In two comatose patients admitted to the Intensive Care Unit (ICU) with severe postanoxic encephalopathy and burst-suppression EEG, we studied the effect of external stimuli (sound and touch) on the occurrence of bursts. In patient A bursts could be induced by either auditory or sensory stimuli. In patient B bursts could only be induced by touching different facial regions (forehead, nose and chin). When stimuli were presented with relatively long intervals, bursts persistently followed the stimuli, while stimuli with short intervals (encephalopathy can be induced by external stimuli, resulting in stimulus-dependent burst-suppression. Stimulus induced bursts should not be interpreted as prognostic favourable EEG reactivity. Copyright © 2016 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.
Inhibition of somatosensory-evoked cortical responses by a weak leading stimulus.
Nakagawa, Kei; Inui, Koji; Yuge, Louis; Kakigi, Ryusuke
2014-11-01
We previously demonstrated that auditory-evoked cortical responses were suppressed by a weak leading stimulus in a manner similar to the prepulse inhibition (PPI) of startle reflexes. The purpose of the present study was to investigate whether a similar phenomenon was present in the somatosensory system, and also whether this suppression reflected an inhibitory process. We recorded somatosensory-evoked magnetic fields following stimulation of the median nerve and evaluated the extent by which they were suppressed by inserting leading stimuli at an intensity of 2.5-, 1.5-, 1.1-, or 0.9-fold the sensory threshold (ST) in healthy participants (Experiment 1). The results obtained demonstrated that activity in the secondary somatosensory cortex in the hemisphere contralateral to the stimulated side (cSII) was significantly suppressed by a weak leading stimulus with the intensity larger than 1.1-fold ST. This result implied that the somatosensory system had an inhibitory process similar to that of PPI. We then presented two successive leading stimuli before the test stimulus, and compared the extent of suppression between the test stimulus-evoked responses and those obtained with the second prepulse alone and with two prepulses (first and second) (Experiment 2). When two prepulses were preceded, cSII responses to the second prepulse were suppressed by the first prepulse, whereas the ability of the second prepulse to suppress the test stimulus remained unchanged. These results suggested the presence of at least two individual pathways; response-generating and inhibitory pathways. Copyright © 2014 Elsevier Inc. All rights reserved.
The modulation of simple reaction time by the spatial probability of a visual stimulus
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Carreiro L.R.R.
2003-01-01
Full Text Available Simple reaction time (SRT in response to visual stimuli can be influenced by many stimulus features. The speed and accuracy with which observers respond to a visual stimulus may be improved by prior knowledge about the stimulus location, which can be obtained by manipulating the spatial probability of the stimulus. However, when higher spatial probability is achieved by holding constant the stimulus location throughout successive trials, the resulting improvement in performance can also be due to local sensory facilitation caused by the recurrent spatial location of a visual target (position priming. The main objective of the present investigation was to quantitatively evaluate the modulation of SRT by the spatial probability structure of a visual stimulus. In two experiments the volunteers had to respond as quickly as possible to the visual target presented on a computer screen by pressing an optic key with the index finger of the dominant hand. Experiment 1 (N = 14 investigated how SRT changed as a function of both the different levels of spatial probability and the subject's explicit knowledge about the precise probability structure of visual stimulation. We found a gradual decrease in SRT with increasing spatial probability of a visual target regardless of the observer's previous knowledge concerning the spatial probability of the stimulus. Error rates, below 2%, were independent of the spatial probability structure of the visual stimulus, suggesting the absence of a speed-accuracy trade-off. Experiment 2 (N = 12 examined whether changes in SRT in response to a spatially recurrent visual target might be accounted for simply by sensory and temporally local facilitation. The findings indicated that the decrease in SRT brought about by a spatially recurrent target was associated with its spatial predictability, and could not be accounted for solely in terms of sensory priming.
Johnson, Tiffany A; Baranowski, Lauren G
2012-01-01
To determine whether common approaches to setting stimulus parameters influence the depth of fine structure present in the distortion product otoacoustic emission (DPOAE) response. Because the presence of fine structure has been suggested as a possible source of errors, if one of the common parametric approaches results in reduced fine-structure depth, it may be preferred over other approaches. DPOAE responses were recorded in a group of 21 subjects with normal hearing for 1/3-octave intervals surrounding 3 f2s (1, 2, and 4 kHz) at three L2s (30, 45, and 55 dB SPL). For each f2 and L2 combination, L1 and f2/f1 were set according to three commonly used parametric approaches. These included a simple approach, the approach recommended by Kummer et al., and the approach described by Johnson et al. These three approaches primarily differ in the recommended relationship between L1 and L2. For each parametric approach, DPOAE fine structure was evaluated by varying f2 in small steps. Differences in DPOAE level and DPOAE fine-structure depth across f2, L2, and the various stimulus parameters were evaluated using repeated-measures analysis of variance. As expected, significant variations in DPOAE level were observed across the three parametric approaches. For stimulus levels #45 dB SPL, the simple stimuli resulted in lower DPOAE levels than were observed for other approaches. An unexpected finding was that stimulus parameters developed by Johnson et al., which were believed to produce higher DPOAE levels than other approaches, produced the lowest DPOAE levels of the three approaches when f2 = 4 kHz. Significant differences in fine-structure depth were also observed. Greater fine-structure depth was observed with the simple parameters, although this effect was restricted to L2 # 45 dB SPL. When L2 = 55 dB SPL, all three parametric approaches resulted in equivalent fine-structure depth. A significant difference in fine-structure depth across the 3 f2s was also observed. The
Significance of a notch in the otoacoustic emission stimulus spectrum.
Grenner, J
2012-09-01
To explain a clinical observation: a notch in the stimulus spectrum during transient evoked otoacoustic emission measurement in ears with secretory otitis media. The effects of tympanic under-pressure were investigated using a pressure chamber. A model of the ear canal was also studied. Tympanic membrane reflectance increased as a consequence of increased stiffness, causing a notch in the stimulus spectrum. In an adult, the notch could be clearly distinguished at an under-pressure of approximately -185 daPa. The sound frequency of the notch corresponded to a wavelength four times the ear canal length. The ear canal of infants was too short to cause a notch within the displayed frequency range. The notch was demonstrated using both Otodynamics and Madsen equipment. A notch in the otoacoustic emission stimulus spectrum can be caused by increased stiffness of the tympanic membrane, raising suspicion of low middle-ear pressure or secretory otitis media. This finding is not applicable to infants.
International Nuclear Information System (INIS)
Hu, Bing; Wang, Qingyun
2015-01-01
Epilepsy is a typical neural disease in nervous system, and the control of seizures is very important for treating the epilepsy. It is well known that the drug treatment is the main strategy for controlling the epilepsy. However, there are about 10–15 percent of patients, whose seizures cannot be effectively controlled by means of the drug. Alternatively, the deep brain stimulus (DBS) technology is a feasible method to control the serious seizures. However, theoretical explorations of DBS are still absent, and need to be further made. Presently, we will explore to control the absence seizures by introducing the DBS to a basal ganglia thalamocortical network model. In particular, we apply DBS onto substantia nigra pars reticulata (SNr) and the cortex to explore its effects on controlling absence seizures, respectively. We can find that the absence seizure can be well controlled within suitable parameter ranges by tuning the period and duration of current stimulation as DBS is implemented in the SNr. And also, as the DBS is applied onto the cortex, it is shown that for the ranges of present parameters, only adjusting the duration of current stimulation is an effective control method for the absence seizures. The obtained results can have better understanding for the mechanism of DBS in the medical treatment.
Shinohe, Yutaka; Higuchi, Satomi; Sasaki, Makoto; Sato, Masahito; Noda, Mamoru; Joh, Shigeharu; Satoh, Kenichi
2016-12-07
Conscious sedation with propofol sometimes causes amnesia while keeping the patient awake. However, it remains unknown how propofol compromises the memory function. Therefore, we investigated the changes in brain activation induced by visual stimulation during and after conscious sedation with propofol using serial functional MRI. Healthy volunteers received a target-controlled infusion of propofol, and underwent functional MRI scans with a block-design paradigm of visual stimulus before, during, and after conscious sedation. Random-effect model analyses were performed using Statistical Parametric Mapping software. Among the areas showing significant activation in response to the visual stimulus, the visual cortex and fusiform gyrus were significantly suppressed in the sedation session and tended to recover in the early-recovery session of ∼20 min (Psedation and early-recovery sessions (Psedation with propofol may cause prolonged suppression of the activation of memory-related structures, such as the hippocampus, during the early-recovery period, which may lead to transient amnesia.
Crisis, Stimulus Package and Migration in China
Csanádi, Maria; Nie, Zihan; Li, Shi
2015-01-01
This paper analyzes the short-term and long-term effects that the global economic crisis and the investment priorities of the Chinese Government's stimulus package had on Chinese migrant flows between 2008 and 2014. Combining micro-level household survey data and macro-level statistics, the
Bigrams and the Richness of the Stimulus
Kam, Xuan-Nga Cao; Stoyneshka, Iglika; Tornyova, Lidiya; Fodor, Janet D.; Sakas, William G.
2008-01-01
Recent challenges to Chomsky's "poverty of the stimulus" thesis for language acquisition suggest that children's primary data may carry "indirect evidence" about linguistic constructions despite containing no instances of them. Indirect evidence is claimed to suffice for grammar acquisition, without need for innate knowledge. This article reports…
Yoles-Frenkel, Michal; Cohen, Oksana; Bansal, Rohini; Horesh, Noa; Ben-Shaul, Yoram
2017-06-15
Achieving controlled stimulus delivery is a major challenge in the physiological analysis of the vomeronasal system (VNS). We provide a comprehensive description of a setup allowing controlled stimulus delivery into the vomeronasal organ (VNO) of anesthetized mice. VNO suction is achieved via electrical stimulation of the sympathetic nerve trunk (SNT) using cuff electrodes, followed by flushing of the nasal cavity. Successful application of this methodology depends on several aspects including the surgical preparation, fabrication of cuff electrodes, experimental setup modifications, and the stimulus delivery and flushing. Here, we describe all these aspects in sufficient detail to allow other researchers to readily adopt it. We also present a custom written MATLAB based software with a graphical user interface that controls all aspects of the actual experiment, including trial sequencing, hardware control, and data logging. The method allows measurement of stimulus evoked sensory responses in brain regions that receive vomeronasal inputs. An experienced investigator can complete the entire surgical procedure within thirty minutes. This is the only approach that allows repeated and controlled stimulus delivery to the intact VNO, employing the natural mode of stimulus uptake. The approach is economical with respect to stimuli, requiring stimulus volumes as low as 1-2μl. This comprehensive description will allow other investigators to adapt this setup to their own experimental needs and can thus promote our physiological understanding of this fascinating chemosensory system. With minor changes it can also be adapted for other rodent species. Copyright © 2017 Elsevier B.V. All rights reserved.
Autonomous stimulus triggered self-healing in smart structural composites
International Nuclear Information System (INIS)
Norris, C J; White, J A P; McCombe, G; Chatterjee, P; Bond, I P; Trask, R S
2012-01-01
Inspired by the ability of biological systems to sense and autonomously heal damage, this research has successfully demonstrated the first autonomous, stimulus triggered, self-healing system in a structural composite material. Both the sensing and healing mechanisms are reliant on microvascular channels incorporated within a laminated composite material. For the triggering mechanism, a single air filled vessel was pressurized, sealed and monitored. Upon drop weight impact (10 J), delamination and microcrack connectivity between the pressurized vessel and those open to ambient led to a pressure loss which, with the use of a suitable sensor, triggered a pump to deliver a healing agent to the damage zone. Using this autonomous healing approach, near full recovery of post-impact compression strength was achieved (94% on average). A simplified alternative system with healing agent continuously flowing through the vessels, akin to blood flow, was found to offer 100% recovery of the material’s virgin strength. Optical microscopy and ultrasonic C-scanning provided further evidence of large-scale infusion of matrix damage with the healing agent. The successful implementation of this bioinspired technology could substantially enhance the integrity and reliability of aerospace structures, whilst offering benefits through improved performance/weight ratios and extended lifetimes. (paper)
de Gelder, Beatrice; Van den Stock, Jan
2011-01-01
Whole body expressions are among the main visual stimulus categories that are naturally associated with faces and the neuroscientific investigation of how body expressions are processed has entered the research agenda this last decade. Here we describe the stimulus set of whole body expressions termed bodily expressive action stimulus test (BEAST), and we provide validation data for use of these materials by the community of emotion researchers. The database was composed of 254 whole body expressions from 46 actors expressing 4 emotions (anger, fear, happiness, and sadness). In all pictures the face of the actor was blurred and participants were asked to categorize the emotions expressed in the stimuli in a four alternative-forced-choice task. The results show that all emotions are well recognized, with sadness being the easiest, followed by fear, whereas happiness was the most difficult. The BEAST appears a valuable addition to currently available tools for assessing recognition of affective signals. It can be used in explicit recognition tasks as well as in matching tasks and in implicit tasks, combined either with facial expressions, with affective prosody, or presented with affective pictures as context in healthy subjects as well as in clinical populations.
Stimulus recognition occurs under high perceptual load: Evidence from correlated flankers.
Cosman, Joshua D; Mordkoff, J Toby; Vecera, Shaun P
2016-12-01
A dominant account of selective attention, perceptual load theory, proposes that when attentional resources are exhausted, task-irrelevant information receives little attention and goes unrecognized. However, the flanker effect-typically used to assay stimulus identification-requires an arbitrary mapping between a stimulus and a response. We looked for failures of flanker identification by using a more-sensitive measure that does not require arbitrary stimulus-response mappings: the correlated flankers effect. We found that flanking items that were task-irrelevant but that correlated with target identity produced a correlated flanker effect. Participants were faster on trials in which the irrelevant flanker had previously correlated with the target than when it did not. Of importance, this correlated flanker effect appeared regardless of perceptual load, occurring even in high-load displays that should have abolished flanker identification. Findings from a standard flanker task replicated the basic perceptual load effect, with flankers not affecting response times under high perceptual load. Our results indicate that task-irrelevant information can be processed to a high level (identification), even under high perceptual load. This challenges a strong account of high perceptual load effects that hypothesizes complete failures of stimulus identification under high perceptual load. (PsycINFO Database Record (c) 2016 APA, all rights reserved).
Simple 3-D stimulus for motion parallax and its simulation.
Ono, Hiroshi; Chornenkyy, Yevgen; D'Amour, Sarah
2013-01-01
Simulation of a given stimulus situation should produce the same perception as the original. Rogers et al (2009 Perception 38 907-911) simulated Wheeler's (1982, PhD thesis, Rutgers University, NJ) motion parallax stimulus and obtained quite different perceptions. Wheeler's observers were unable to reliably report the correct direction of depth, whereas Rogers's were. With three experiments we explored the possible reasons for the discrepancy. Our results suggest that Rogers was able to see depth from the simulation partly due to his experience seeing depth with random dot surfaces.
Voss, Joel L; O'Neil, Jonathan T; Kharitonova, Maria; Briggs-Gowan, Margaret J; Wakschlag, Lauren S
2015-01-01
Expression of learned stimulus-reward associations based on context is essential for regulation of behavior to meet situational demands. Contextual regulation improves during development, although the developmental progression of relevant neural and cognitive processes is not fully specified. We therefore measured neural correlates of flexible, contextual expression of stimulus-reward associations in pre/early-adolescent children (ages 9-13 years) and young adults (ages 19-22 years). After reinforcement learning using standard parameters, a contextual reversal manipulation was used whereby contextual cues indicated that stimulus-reward associations were the same as previously reinforced for some trials (consistent trials) or were reversed on other trials (inconsistent trials). Subjects were thus required to respond according to original stimulus-reward associations vs. reversed associations based on trial-specific contextual cues. Children and young adults did not differ in reinforcement learning or in relevant functional magnetic resonance imaging (fMRI) correlates. In contrast, adults outperformed children during contextual reversal, with better performance specifically for inconsistent trials. fMRI signals corresponding to this selective advantage included greater activity in lateral prefrontal cortex (LPFC), hippocampus, and dorsal striatum for young adults relative to children. Flexible expression of stimulus-reward associations based on context thus improves via adolescent development, as does recruitment of brain regions involved in reward learning and contextual expression of memory. HighlightsEarly-adolescent children and young adults were equivalent in reinforcement learning.Adults outperformed children in contextual expression of stimulus-reward associations.Adult advantages correlated with increased activity of relevant brain regions.Specific neurocognitive developmental changes support better contextual regulation.
[Mechanisms and applications of transcutaneous electrical nerve stimulation in analgesia].
Tang, Zheng-Yu; Wang, Hui-Quan; Xia, Xiao-Lei; Tang, Yi; Peng, Wei-Wei; Hu, Li
2017-06-25
Transcutaneous electrical nerve stimulation (TENS), as a non-pharmacological and non-invasive analgesic therapy with low-cost, has been widely used to relieve pain in various clinical applications, by delivering current pulses to the skin area to activate the peripheral nerve fibers. Nevertheless, analgesia induced by TENS varied in the clinical practice, which could be caused by the fact that TENS with different stimulus parameters has different biological mechanisms in relieving pain. Therefore, to advance our understanding of TENS in various basic and clinical studies, we discussed (1) neurophysiological and biochemical mechanisms of TENS-induced analgesia; (2) relevant factors that may influence analgesic effects of TENS from the perspectives of stimulus parameters, including stimulated position, pulse parameters (current intensity, frequency, and pulse width), stimulus duration and used times in each day; and (3) applications of TENS in relieving clinical pain, including post-operative pain, chronic low back pain and labor pain. Finally, we propose that TENS may involve multiple and complex psychological neurophysiological mechanisms, and suggest that different analgesic effects of TENS with different stimulus parameters should be taken into consideration in clinical applications. In addition, to optimize analgesic effect, we recommend that individual-based TENS stimulation parameters should be designed by considering individual differences among patients, e.g., adaptively adjusting the stimulation parameters based on the dynamic ratings of patients' pain.
Tapia, Evelina; Mazzi, Chiara; Savazzi, Silvia; Beck, Diane M.
2014-01-01
Transcranial magnetic stimulation (TMS) applied over the occipital lobe approximately 100 ms after the onset of a stimulus decreases its visibility if it appears in the location of the phosphene. Because phosphenes can also be elicited by stimulation of the parietal regions, we asked if the same procedure that is used to reduce visibility of stimuli with occipital TMS will lead to decreased stimulus visibility when TMS is applied to parietal regions. TMS was randomly applied at 0 to 130 ms after the onset of the stimulus (SOA) in steps of 10 ms in occipital and parietal regions. Participants responded to the orientation of the line stimulus and rated its visibility. We replicate previous reports of phosphenes from both occipital and parietal TMS. As previously reported, we also observed visual suppression around the classical 100 ms window both in the objective line orientation and subjective visibility responses with occipital TMS. Parietal stimulation, on the other hand, did not consistently reduce stimulus visibility in any time window. PMID:24584900
Isomorphism Between Estes’ Stimulus Fluctuation Model and a Physical- Chemical System
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Makoto Yamaguchi
2013-10-01
Full Text Available Although Estes’ Stimulus Sampling Theory has almost completely lost its influence, its theoretical framework has not been disproved. Particularly, one theory in that framework, Stimulus Fluctuation Model, is still important because it explains spontaneous recovery. In this short note, the process of the theory is shown to be isomorphic to the diffusion of solution between compartments. Envisioning the theory as diffusion will make it appear less artificial and suggest natural extensions.
Bode, Stefan; Bennett, Daniel; Sewell, David K; Paton, Bryan; Egan, Gary F; Smith, Philip L; Murawski, Carsten
2018-03-01
According to sequential sampling models, perceptual decision-making is based on accumulation of noisy evidence towards a decision threshold. The speed with which a decision is reached is determined by both the quality of incoming sensory information and random trial-by-trial variability in the encoded stimulus representations. To investigate those decision dynamics at the neural level, participants made perceptual decisions while functional magnetic resonance imaging (fMRI) was conducted. On each trial, participants judged whether an image presented under conditions of high, medium, or low visual noise showed a piano or a chair. Higher stimulus quality (lower visual noise) was associated with increased activation in bilateral medial occipito-temporal cortex and ventral striatum. Lower stimulus quality was related to stronger activation in posterior parietal cortex (PPC) and dorsolateral prefrontal cortex (DLPFC). When stimulus quality was fixed, faster response times were associated with a positive parametric modulation of activation in medial prefrontal and orbitofrontal cortex, while slower response times were again related to more activation in PPC, DLPFC and insula. Our results suggest that distinct neural networks were sensitive to the quality of stimulus information, and to trial-to-trial variability in the encoded stimulus representations, but that reaching a decision was a consequence of their joint activity. Copyright © 2018 Elsevier Ltd. All rights reserved.
An Adaptive Neural Mechanism for Acoustic Motion Perception with Varying Sparsity.
Shaikh, Danish; Manoonpong, Poramate
2017-01-01
Biological motion-sensitive neural circuits are quite adept in perceiving the relative motion of a relevant stimulus. Motion perception is a fundamental ability in neural sensory processing and crucial in target tracking tasks. Tracking a stimulus entails the ability to perceive its motion, i.e., extracting information about its direction and velocity. Here we focus on auditory motion perception of sound stimuli, which is poorly understood as compared to its visual counterpart. In earlier work we have developed a bio-inspired neural learning mechanism for acoustic motion perception. The mechanism extracts directional information via a model of the peripheral auditory system of lizards. The mechanism uses only this directional information obtained via specific motor behaviour to learn the angular velocity of unoccluded sound stimuli in motion. In nature however the stimulus being tracked may be occluded by artefacts in the environment, such as an escaping prey momentarily disappearing behind a cover of trees. This article extends the earlier work by presenting a comparative investigation of auditory motion perception for unoccluded and occluded tonal sound stimuli with a frequency of 2.2 kHz in both simulation and practice. Three instances of each stimulus are employed, differing in their movement velocities-0.5°/time step, 1.0°/time step and 1.5°/time step. To validate the approach in practice, we implement the proposed neural mechanism on a wheeled mobile robot and evaluate its performance in auditory tracking.
Morawetz, Carmen; Bode, Stefan; Derntl, Birgit; Heekeren, Hauke R
2017-01-01
Emotion regulation comprises all extrinsic and intrinsic control processes whereby people monitor, evaluate and modify the occurrence, intensity and duration of emotional reactions. Here we sought to quantitatively summarize the existing neuroimaging literature to investigate a) whether different emotion regulation strategies are based on different or the same neural networks; b) which brain regions in particular support the up- and down-regulation of emotions, respectively; and c) to which degree the neural networks realising emotion regulation depend on the stimulus material used to elicit emotions. The left ventrolateral prefrontal cortex (VLPFC), the anterior insula and the supplementary motor area were consistently activated independent of the regulation strategy. VLPFC and posterior cingulate cortex were the main regions consistently found to be recruited during the up-regulation as well as the down-regulation of emotion. The down-regulation compared to the up-regulation of emotions was associated with more right-lateralized activity while up-regulating emotions more strongly modulated activity in the ventral striatum. Finally, the process of emotion regulation appeared to be unaffected by stimulus material. Copyright © 2016 Elsevier Ltd. All rights reserved.
Human event-related brain potentials to auditory periodic noise stimuli.
Kaernbach, C; Schröger, E; Gunter, T C
1998-02-06
Periodic noise is perceived as different from ordinary non-repeating noise due to the involvement of echoic memory. Since this stimulus does not contain simple physical cues (such as onsets or spectral shape) that might obscure sensory memory interpretations, it is a valuable tool to study sensory memory functions. We demonstrated for the first time that the processing of periodic noise can be tapped by event-related brain potentials (ERPs). Human subjects received repeating segments of noise embedded in non-repeating noise. They were instructed to detect the periodicity inherent to the stimulation. We observed a central negativity time-locked on the periodic segment that correlated to the subjects behavioral performance in periodicity detection. It is argued that the ERP result indicates an enhancement of sensory-specific processing.
Benwell, Christopher S Y; Harvey, Monika; Gardner, Stephanie; Thut, Gregor
2013-03-01
Systematic biases in spatial attention are a common finding. In the general population, a systematic leftward bias is typically observed (pseudoneglect), possibly as a consequence of right hemisphere dominance for visuospatial attention. However, this leftward bias can cross-over to a systematic rightward bias with changes in stimulus and state factors (such as line length and arousal). The processes governing these changes are still unknown. Here we tested models of spatial attention as to their ability to account for these effects. To this end, we experimentally manipulated both stimulus and state factors, while healthy participants performed a computerized version of a landmark task. State was manipulated by time-on-task (>1 h) leading to increased fatigue and a reliable left- to rightward shift in spatial bias. Stimulus was manipulated by presenting either long or short lines which was associated with a shift of subjective midpoint from a reliable leftward bias for long to a more rightward bias for short lines. Importantly, we found time-on-task and line length effects to be additive suggesting a common denominator for line bisection across all conditions, which is in disagreement with models that assume that bisection decisions in long and short lines are governed by distinct processes (Magnitude estimation vs Global/local distinction). Our findings emphasize the dynamic rather than static nature of spatial biases in midline judgement. They are best captured by theories of spatial attention positing that spatial bias is flexibly modulated, and subject to inter-hemispheric balance which can change over time or conditions to accommodate task demands or reflect fatigue. Copyright © 2012 Elsevier Ltd. All rights reserved.
Directory of Open Access Journals (Sweden)
Hannah V Wilson
Full Text Available The influence of methodological parameters on the measurement of muscle contractile properties using Tensiomyography (TMG has not been published.To investigate the; (1 reliability of stimulus amplitude needed to elicit maximum muscle displacement (Dm, (2 effect of changing inter-stimulus interval on Dm (using a fixed stimulus amplitude and contraction time (Tc, (3 the effect of changing inter-electrode distance on Dm and Tc.Within subject, repeated measures.10 participants for each objective.Dm and Tc of the rectus femoris, measured using TMG.The coefficient of variance (CV and the intra-class correlation (ICC of stimulus amplitude needed to elicit maximum Dm was 5.7% and 0.92 respectively. Dm was higher when using an inter-electrode distance of 7cm compared to 5cm [P = 0.03] and when using an inter-stimulus interval of 10s compared to 30s [P = 0.017]. Further analysis of inter-stimulus interval data, found that during 10 repeated stimuli Tc became faster after the 5th measure when compared to the second measure [P<0.05]. The 30s inter-stimulus interval produced the most stable Tc over 10 measures compared to 10s and 5s respectively.Our data suggest that the stimulus amplitude producing maximum Dm of the rectus femoris is reliable. Inter-electrode distance and inter-stimulus interval can significantly influence Dm and/ or Tc. Our results support the use of a 30s inter-stimulus interval over 10s or 5s. Future studies should determine the influence of methodological parameters on muscle contractile properties in a range of muscles.
Johnson, Mark I.; Francis, Peter
2018-01-01
Context The influence of methodological parameters on the measurement of muscle contractile properties using Tensiomyography (TMG) has not been published. Objective To investigate the; (1) reliability of stimulus amplitude needed to elicit maximum muscle displacement (Dm), (2) effect of changing inter-stimulus interval on Dm (using a fixed stimulus amplitude) and contraction time (Tc), (3) the effect of changing inter-electrode distance on Dm and Tc. Design Within subject, repeated measures. Participants 10 participants for each objective. Main outcome measures Dm and Tc of the rectus femoris, measured using TMG. Results The coefficient of variance (CV) and the intra-class correlation (ICC) of stimulus amplitude needed to elicit maximum Dm was 5.7% and 0.92 respectively. Dm was higher when using an inter-electrode distance of 7cm compared to 5cm [P = 0.03] and when using an inter-stimulus interval of 10s compared to 30s [P = 0.017]. Further analysis of inter-stimulus interval data, found that during 10 repeated stimuli Tc became faster after the 5th measure when compared to the second measure [P<0.05]. The 30s inter-stimulus interval produced the most stable Tc over 10 measures compared to 10s and 5s respectively. Conclusion Our data suggest that the stimulus amplitude producing maximum Dm of the rectus femoris is reliable. Inter-electrode distance and inter-stimulus interval can significantly influence Dm and/ or Tc. Our results support the use of a 30s inter-stimulus interval over 10s or 5s. Future studies should determine the influence of methodological parameters on muscle contractile properties in a range of muscles. PMID:29451885
de Graaf, Tom A; Cornelsen, Sonja; Jacobs, Christianne; Sack, Alexander T
2011-12-01
Transcranial magnetic stimulation (TMS) can be used to mask visual stimuli, disrupting visual task performance or preventing visual awareness. While TMS masking studies generally fix stimulation intensity, we hypothesized that varying the intensity of TMS pulses in a masking paradigm might inform several ongoing debates concerning TMS disruption of vision as measured subjectively versus objectively, and pre-stimulus (forward) versus post-stimulus (backward) TMS masking. We here show that both pre-stimulus TMS pulses and post-stimulus TMS pulses could strongly mask visual stimuli. We found no dissociations between TMS effects on the subjective and objective measures of vision for any masking window or intensity, ruling out the option that TMS intensity levels determine whether dissociations between subjective and objective vision are obtained. For the post-stimulus time window particularly, we suggest that these data provide new constraints for (e.g. recurrent) models of vision and visual awareness. Finally, our data are in line with the idea that pre-stimulus masking operates differently from conventional post-stimulus masking. Copyright © 2011 Elsevier Inc. All rights reserved.
Stimulus Competition in Pre/Post and Online Ratings in an Evaluative Learning Design
Purkis, Helena M.; Lipp, Ottmar V.
2010-01-01
Evaluative learning is said to differ from Pavlovian associative learning in that it reflects stimulus contiguity, not contingency. Thus, evaluative learning should not be subject to stimulus competition, a proposal tested in the current experiments. Participants were presented in elemental and compound training phases with pictures of shapes as…
Zhou, Hong; Melloni, Lucia; Poeppel, David; Ding, Nai
2016-01-01
Brain activity can follow the rhythms of dynamic sensory stimuli, such as speech and music, a phenomenon called neural entrainment. It has been hypothesized that low-frequency neural entrainment in the neural delta and theta bands provides a potential mechanism to represent and integrate temporal information. Low-frequency neural entrainment is often studied using periodically changing stimuli and is analyzed in the frequency domain using the Fourier analysis. The Fourier analysis decomposes a periodic signal into harmonically related sinusoids. However, it is not intuitive how these harmonically related components are related to the response waveform. Here, we explain the interpretation of response harmonics, with a special focus on very low-frequency neural entrainment near 1 Hz. It is illustrated why neural responses repeating at f Hz do not necessarily generate any neural response at f Hz in the Fourier spectrum. A strong neural response at f Hz indicates that the time scales of the neural response waveform within each cycle match the time scales of the stimulus rhythm. Therefore, neural entrainment at very low frequency implies not only that the neural response repeats at f Hz but also that each period of the neural response is a slow wave matching the time scale of a f Hz sinusoid.
Post-stimulus endogenous and exogenous oscillations are differentially modulated by task difficulty.
Li, Yun; Lou, Bin; Gao, Xiaorong; Sajda, Paul
2013-01-01
We investigate the modulation of post-stimulus endogenous and exogenous oscillations when a visual discrimination is made more difficult. We use exogenous frequency tagging to induce steady-state visually evoked potentials (SSVEP) while subjects perform a face-car discrimination task, the difficulty of which varies on a trial-to-trial basis by varying the noise (phase coherence) in the image. We simultaneously analyze amplitude modulations of the SSVEP and endogenous alpha activity as a function of task difficulty. SSVEP modulation can be viewed as a neural marker of attention toward/away from the primary task, while modulation of post-stimulus alpha is closely related to cortical information processing. We find that as the task becomes more difficult, the amplitude of SSVEP decreases significantly, approximately 250-450 ms post-stimulus. Significant changes in endogenous alpha amplitude follow SSVEP modulation, occurring at approximately 400-700 ms post-stimulus and, unlike the SSVEP, the alpha amplitude is increasingly suppressed as the task becomes less difficult. Our results demonstrate simultaneous measurement of endogenous and exogenous oscillations that are modulated by task difficulty, and that the specific timing of these modulations likely reflects underlying information processing flow during perceptual decision-making.
Development of a Chirp Stimulus PC-Based Auditory Brainstem Response Audiometer
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Ali AL-Afsaa
2004-05-01
Full Text Available Hearing losses during infancy and childhood have many negative future effects and impacts on the child life and productivity. The earlier detection of hearing losses, the earlier medical intervention and then the greater benefit of remediation will be. During this research a PC-based audiometer is designed and, currently, the audiometer prototype is in its final development steps. It is based on the auditory brainstem response (ABR method. Chirp stimuli instead of traditional click stimuli will be used to invoke the ABR signal. The stimulus is designed to synchronize the hair cells movement when it spreads out over the cochlea. In addition to the available hardware utilization (PC and PCI board, the efforts confined to design and implement a hardware prototype and to develop a software package that enables the system to behave as ABR audiometer. By using such a method and chirp stimulus, it is expected to be able to detect hearing impairment (sensorineural in the first few days of the life and conduct hearing test at low frequency of stimulus. Currently, the intended chirp stimulus has been successfully generated and the implemented module is able to amplify a signal (on the order of ABR signal to a recordable level. Moreover, a NI-DAQ data acquisition board has been chosen to implement the PC-prototype interface.
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Creath Robert A
2013-01-01
Full Text Available Abstract Background Prior studies demonstrated that hesitation-prone persons with Parkinson’s disease (PDs acutely improve step initiation using a novel self-triggered stimulus that enhances lateral weight shift prior to step onset. PDs showed reduced anticipatory postural adjustment (APA durations, earlier step onsets, and faster 1st step speed immediately following stimulus exposure. Objective This study investigated the effects of long-term stimulus exposure. Methods Two groups of hesitation-prone subjects with Parkinson’s disease (PD participated in a 6-week step-initiation training program involving one of two stimulus conditions: 1 Drop. The stance-side support surface was lowered quickly (1.5 cm; 2 Vibration. A short vibration (100 ms was applied beneath the stance-side support surface. Stimuli were self-triggered by a 5% reduction in vertical force under the stance foot during the APA. Testing was at baseline, immediately post-training, and 6 weeks post-training. Measurements included timing and magnitude of ground reaction forces, and step speed and length. Results Both groups improved their APA force modulation after training. Contrary to previous results, neither group showed reduced APA durations or earlier step onset times. The vibration group showed 55% increase in step speed and a 39% increase in step length which were retained 6 weeks post-training. The drop group showed no stepping-performance improvements. Conclusions The acute sensitivity to the quickness-enhancing effects of stimulus exposure demonstrated in previous studies was supplanted by improved force modulation following prolonged stimulus exposure. The results suggest a potential approach to reduce the severity of start hesitation in PDs, but further study is needed to understand the relationship between short- and long-term effects of stimulus exposure.
Experimental studies on the mechanism of leukemogenesis following the hemopoietic stem cell kinetics
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Bessho, Masami; Hirashima, Kunitake (National Inst. of Radiological Sciences, Chiba (Japan))
1982-12-01
The mechanism of radiation-induced myeloid leukemogenesis was studied experimentally following the hemopoietic stem cell kinetics. Pluripotent stem cells (CFU-S) regarded as target cells to Friend virus (FV) were highly susceptible to leukemic cell transformation by FV during the regeneration period after irradiation. Experimental studies using RFM mice revealed that (1) the period of leukemic transformation closely corresponded to the prolonged suppressive period of CFU-C after irradiation, when significantly increased fraction of CFU-C is in S-phase, (2) the leukemic cell transformation after irradiation occurred earlier and more frequently than the overt leukemia, (3) some unknown host factors except cellular immunity played an important role in the establishment of overt leukemia, (4) lipopolysaccharide administrated after irradiation increased the incidence of myeloid leukemia whereas urethane decreased it. Another experimental systems using C3H/He mice bearing CSF-producing tumor revealed that the incidence of myeloid leukemia after a low-dose irradiation increased when CFU-S and CFU-C were proliferating and differentiating actively by the stimulus of CSF produced by the tumor. The mechanism of this phenomenon can be regarded as the activation of leukemia virus in irradiated bodies.
The effects of stimulus competition and voluntary attention on colour-graphemic synaesthesia.
Rich, Anina N; Mattingley, Jason B
2003-10-06
Colour-graphemic synaesthetes experience vivid colours when reading letters, digits and words. We examined the effect of stimulus competition and attention on these unusual colour experiences in 14 synaesthetes and 14 non-synaesthetic controls. Participants named the colour of hierarchical local-global stimuli in which letters at each level elicited synaesthetic colours that were congruent or incongruent with the display colour. Synaesthetes were significantly slower to name display colours when either level was incongruent than when both levels were congruent. This effect was significantly reduced when synaesthetes focused attention on one level while the congruency of letters at the ignored level was varied. These findings suggest that competition between multiple inducers and mechanisms of voluntary attention influence colour-graphemic synaesthesia.
Evaluation of an Efficient Method for Training Staff to Implement Stimulus Preference Assessments
Roscoe, Eileen M.; Fisher, Wayne W.
2008-01-01
We used a brief training procedure that incorporated feedback and role-play practice to train staff members to conduct stimulus preference assessments, and we used group-comparison methods to evaluate the effects of training. Staff members were trained to implement the multiple-stimulus-without-replacement assessment in a single session and the…
Effects of stimulus duration on gustatory evoked potentials
DEFF Research Database (Denmark)
Rotvel, Camilla Arndal; Møller, Stine; Kivisaar, Kätlin
The objective of the present study was to investigate the effect of tastant stimulus duration on the brain response. The brain response was measured by electroencephalography (EEG) which measures neural processes with high temporal resolution and may therefore complement sensory panel assessments...
Discrepancy between stimulus response and tolerance of pain in Alzheimer disease
DEFF Research Database (Denmark)
Jensen-Dahm, Christina; Werner, Mads U; Jensen, Troels Staehelin
2015-01-01
BACKGROUND: Affective-motivational and sensory-discriminative aspects of pain were investigated in patients with mild to moderate Alzheimer disease (AD) and healthy elderly controls using the cold pressor test tolerance and repetitive stimuli of warmth and heat stimuli, evaluating the stimulus....... The results further suggest that the attenuated cold pressor pain tolerance may relate to impairment of coping abilities. Paradoxically, we found an attenuated stimulus-response function, compared to controls, suggesting that AD dementia interferes with pain ratings over time, most likely due to memory...
Tooth pulp stimulation as an unconditioned stimulus in defensive instrumental conditioning.
Jastreboff, P J; Keller, O; Zieliński, K
1977-01-01
In an experiment performed on five cats, stable escape and avoidance reflexes in a bar-pressing situation were established using tooth pulp electric stimulation as the unconditioned stimulus. The influence of changes in parameters of the unconditioned stimulus (current intensity, single pulse and train durations, frequency of pulses and rate of train presentations) on unconditioned and instrumental responses was analysed in three additional subjects. Among other relationships the dependence of the threshold of bar press responses on the amount of charge in a single pulse was determined.
The acute effect of a plyometric stimulus on jump performance in professional rugby players.
Tobin, Daniel P; Delahunt, Eamonn
2014-02-01
Post-activation potentiation (PAP) is the elevation of motor performance to a higher level in response to a conditioning stimulus. Extensive research exists examining the PAP effect after a heavy resistance exercise. However, there is limited research examining the PAP effect after a plyometric stimulus. This study was designed to examine whether a plyometric stimulus could produce a PAP effect comparable to that typically reported with a heavy resistance protocol. Importantly, it was hypothesized that the PAP effect would exist without the same levels of acute fatigue resulting from a heavy stimulus, thus allowing improvement in performance within a short rest interval range. Twenty professional rugby players were recruited for the study. Subjects performed 2 countermovement jumps (CMJs) at baseline and at 1, 3, and 5 minutes after a plyometric stimulus consisting of 40 jumps. Two separate 1-way repeated-measures analyses of variance were conducted to compare the dependent variables CMJ height and peak force at the 4 time points. Results of the Bonferroni adjusted pairwise comparisons indicated that jump height and peak force before plyometric exercises were significantly lower than all other time points (p plyometric exercises causes a significant acute enhancement in CMJ height (p plyometric series induced an improvement in CMJ height comparable to that reported elsewhere after a heavy lifting stimulus but without the need for a prolonged rest interval. Performing repeated series of plyometric jumps appears to be an efficient method of taking advantage of the PAP phenomenon, thus possibly eliminating the need for a complex training protocol.
Emotional Picture and Word Processing: An fMRI Study on Effects of Stimulus Complexity
Schlochtermeier, Lorna H.; Kuchinke, Lars; Pehrs, Corinna; Urton, Karolina; Kappelhoff, Hermann; Jacobs, Arthur M.
2013-01-01
Neuroscientific investigations regarding aspects of emotional experiences usually focus on one stimulus modality (e.g., pictorial or verbal). Similarities and differences in the processing between the different modalities have rarely been studied directly. The comparison of verbal and pictorial emotional stimuli often reveals a processing advantage of emotional pictures in terms of larger or more pronounced emotion effects evoked by pictorial stimuli. In this study, we examined whether this picture advantage refers to general processing differences or whether it might partly be attributed to differences in visual complexity between pictures and words. We first developed a new stimulus database comprising valence and arousal ratings for more than 200 concrete objects representable in different modalities including different levels of complexity: words, phrases, pictograms, and photographs. Using fMRI we then studied the neural correlates of the processing of these emotional stimuli in a valence judgment task, in which the stimulus material was controlled for differences in emotional arousal. No superiority for the pictorial stimuli was found in terms of emotional information processing with differences between modalities being revealed mainly in perceptual processing regions. While visual complexity might partly account for previously found differences in emotional stimulus processing, the main existing processing differences are probably due to enhanced processing in modality specific perceptual regions. We would suggest that both pictures and words elicit emotional responses with no general superiority for either stimulus modality, while emotional responses to pictures are modulated by perceptual stimulus features, such as picture complexity. PMID:23409009
Kuijk, A.A. van; Bakker, C.D.; Hendriks, J.C.M.; Geurts, A.C.; Stegeman, D.F.; Pasman, J.W.
2014-01-01
BACKGROUND: To explore if stimulus-response (S-R) characteristics of the silent period (SP) after transcranial magnetic stimulation (TMS) are affected by changing the SP definition and by changing data presentation in healthy individuals. This information would be clinically relevant to predict
van Kuijk, A.A.; Bakker, C,; Hendriks, J.J.A.; Geurts, A.H.; Stegeman, D.F.; Pasman, J.W.
2014-01-01
Background: To explore if stimulus-response (S-R) characteristics of the silent period (SP) after transcranial magnetic stimulation (TMS) are affected by changing the SP definition and by changing data presentation in healthy individuals. This information would be clinically relevant to predict
Hesse, Constanze; Franz, Volker H.
2009-01-01
The availability of visual information influences the execution of goal-directed movements. This is very prominent in memory conditions, where a delay is introduced between stimulus presentation and execution of the movement. The corresponding effects could be due to a decay of the visual information or to different processing mechanisms used for…
Pyff---A Pythonic Framework for Feedback Applications and Stimulus Presentation in Neuroscience
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Bastian Venthur
2010-12-01
Full Text Available This paper introduces Pyff, the Pythonic Feedback Framework for feedbackapplications and stimulus presentation. Pyff provides a platform independentframework that allows users to develop and run neuroscientific experiments inthe programming language Python. Existing solutions have mostly beenimplemented in C++, which makes for a rather tedious programming task fornon-computer-scientists, or in Matlab, which is not well suited for moreadvanced visual or auditory applications. Pyff was designed to makeexperimental paradigms (i.e. feedback and stimulus applications easilyprogrammable. It includes base classes for various types of common feedbacksand stimuli as well as useful libraries for external hardware such aseyetrackers. Pyff is also equipped with a steadily growing set of ready-to-usefeedbacks and stimuli. It can be used as a standalone application, for instanceproviding stimulus presentation in psychophysics experiments, or within aclosed loop such as in biofeedback or brain-computer interfacing experiments.Pyff communicates with other systems via a standardized communication protocoland is therefore suitable to be used with any system that may be adapted tosend its data in the specified format. Having such a general, open sourceframework will help foster a fruitful exchange of experimental paradigmsbetween research groups. In particular, it will decrease the need ofreprogramming standard paradigms, ease the reproducibility of publishedresults, and naturally entail some standardization of stimulus presentation.
Measuring voluntary quadriceps activation: Effect of visual feedback and stimulus delivery.
Luc, Brittney A; Harkey, Matthew H; Arguelles, Gabrielle D; Blackburn, J Troy; Ryan, Eric D; Pietrosimone, Brian
2016-02-01
Quadriceps voluntary activation, assessed via the superimposed burst technique, has been extensively studied in a variety of populations as a measure of quadriceps function. However, a variety of stimulus delivery techniques have been employed, which may influence the level of voluntary activation as calculated via the central activation ratio (CAR). The purpose was to determine the effect of visual feedback, stimulus delivery, and perceived discomfort on maximal voluntary isometric contraction (MVIC) peak torque and the CAR. Quadriceps CAR was assessed in 14 individuals on two days using three stimulus delivery methods; (1) manual without visual feedback, (2) manual with visual feedback, and (3) automated with visual feedback. MVIC peak torque and the CAR were not different between the automated with visual feedback (MVIC=3.25, SE=0.14Nm/kg; CAR=88.63, SE=1.75%) and manual with visual feedback (MVIC=3.26, SE=0.13Nm/kg, P=0.859; CAR=89.06, SE=1.70%, P=0.39) stimulus delivery methods. MVIC (2.99, SE=0.12Nm/kg) and CAR (85.32, SE=2.10%) were significantly lower using manual without visual feedback compared to manual with visual feedback and automated with visual feedback (CAR P<0.001; MVIC P<0.001). Perceived discomfort was lower in the second session (P<0.05). Utilizing visual feedback ensures participant MVIC, and may provide a more accurate assessment of quadriceps voluntary activation. Copyright © 2015 Elsevier Ltd. All rights reserved.
Ultrasound as a stimulus for musculoskeletal disorders
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Ning Zhang
2017-04-01
Full Text Available Ultrasound is an inaudible form of acoustic sound wave at 20 kHz or above that is widely used in the medical field with applications including medical imaging and therapeutic stimulation. In therapeutic ultrasound, low-intensity pulsed ultrasound (LIPUS is the most widely used and studied form that generally uses acoustic waves at an intensity of 30 mW/cm2, with 200 ms pulses and 1.5 MHz. In orthopaedic applications, it is used as a biophysical stimulus for musculoskeletal tissue repair to enhance tissue regeneration. LIPUS has been shown to enhance fracture healing by shortening the time to heal and reestablishment of mechanical properties through enhancing different phases of the healing process, including the inflammatory phase, callus formation, and callus remodelling phase. Reports from in vitro studies reveal insights in the mechanism through which acoustic stimulations activate cell surface integrins that, in turn, activate various mechanical transduction pathways including FAK (focal adhesion kinase, ERK (extracellular signal-regulated kinase, PI3K, and Akt. It is then followed by the production of cyclooxygenase 2 and prostaglandin E2 to stimulate further downstream angiogenic, osteogenic, and chondrogenic cytokines, explaining the different enhancements observed in animal and clinical studies. Furthermore, LIPUS has also been shown to have remarkable effects on mesenchymal stem cells (MSCs in musculoskeletal injuries and tissue regeneration. The recruitment of MSCs to injury sites by LIPUS requires the SDF-1 (stromal cell derived factor-1/CXCR-4 signalling axis. MSCs would then differentiate differently, and this is regulated by the presence of different cytokines, which determines their fates. Other musculoskeletal applications including bone–tendon junction healing, and distraction osteogenesis are also explored, and the results are promising. However, the use of LIPUS is controversial in treating osteoporosis, with negative
Emotionally negative pictures increase attention to a subsequent auditory stimulus.
Tartar, Jaime L; de Almeida, Kristen; McIntosh, Roger C; Rosselli, Monica; Nash, Allan J
2012-01-01
Emotionally negative stimuli serve as a mechanism of biological preparedness to enhance attention. We hypothesized that emotionally negative stimuli would also serve as motivational priming to increase attention resources for subsequent stimuli. To that end, we tested 11 participants in a dual sensory modality task, wherein emotionally negative pictures were contrasted with emotionally neutral pictures and each picture was followed 600 ms later by a tone in an auditory oddball paradigm. Each trial began with a picture displayed for 200 ms; half of the trials began with an emotionally negative picture and half of the trials began with an emotionally neutral picture; 600 ms following picture presentation, the participants heard either an oddball tone or a standard tone. At the end of each trial (picture followed by tone), the participants categorized, with a button press, the picture and tone combination. As expected, and consistent with previous studies, we found an enhanced visual late positive potential (latency range=300-700 ms) to the negative picture stimuli. We further found that compared to neutral pictures, negative pictures resulted in early attention and orienting effects to subsequent tones (measured through an enhanced N1 and N2) and sustained attention effects only to the subsequent oddball tones (measured through late processing negativity, latency range=400-700 ms). Number pad responses to both the picture and tone category showed the shortest response latencies and greatest percentage of correct picture-tone categorization on the negative picture followed by oddball tone trials. Consistent with previous work on natural selective attention, our results support the idea that emotional stimuli can alter attention resource allocation. This finding has broad implications for human attention and performance as it specifically shows the conditions in which an emotionally negative stimulus can result in extended stimulus evaluation. Copyright © 2011
Compound Stimulus Extinction Reduces Spontaneous Recovery in Humans
Coelho, Cesar A. O.; Dunsmoor, Joseph E.; Phelps, Elizabeth A.
2015-01-01
Fear-related behaviors are prone to relapse following extinction. We tested in humans a compound extinction design ("deepened extinction") shown in animal studies to reduce post-extinction fear recovery. Adult subjects underwent fear conditioning to a visual and an auditory conditioned stimulus (CSA and CSB, respectively) separately…
The Mechanism of Dishabituation
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Genevieve Z. Steiner
2014-02-01
Full Text Available The dual-process theory of habituation attributes dishabituation, an increase in responding to a habituated stimulus after an interpolated deviant, to sensitisation, a change in arousal. Our previous investigations into elicitation and habituation of the electrodermal Orienting Reflex (OR showed that dishabituation is independent of sensitisation for indifferent stimuli, arguing against dual-process theory’s explanation. However, this could not be tested for significant stimuli in that study, because sensitisation was confounded with incomplete resolution of the preceding OR. This study aimed to clarify the mechanism of dishabituation for significant stimuli by extending the stimulus onset asynchrony (SOA beyond the time required for the phasic response to resolve. Participants completed an auditory dishabituation task with a random SOA of 13-15 s while their electrodermal activity was recorded. The stimulus sequence was 10 standards, 1 deviant, 2-4 standards; counterbalanced innocuous tones. Two counterbalanced conditions were used: silently count all stimuli (significant and no task (indifferent. Skin conductance responses (SCRs and pre-stimulus skin conductance levels (SCLs both decremented over trials 1-10. In both conditions, SCRs showed response recovery and dishabituation, indicating habituation, and post-deviant SCL sensitisation was apparent. Across all trials, phasic ORs were dependent on the pre-stimulus SCL (arousal level; this did not differ with condition. Importantly, dishabituation was independent of sensitisation for both conditions. Findings indicate that sensitisation, the change in state, is a process separate from phasic response resolution, and that arousal consistently predicts OR magnitude, including the dishabituation response. This argues against dual-process theory’s explanation, and instead suggests that dishabituation is a disruption of the habituation process, with magnitude determined by the current arousal
Two Pathways to Stimulus Encoding in Category Learning?
Davis, Tyler; Love, Bradley C.; Maddox, W. Todd
2008-01-01
Category learning theorists tacitly assume that stimuli are encoded by a single pathway. Motivated by theories of object recognition, we evaluate a dual-pathway account of stimulus encoding. The part-based pathway establishes mappings between sensory input and symbols that encode discrete stimulus features, whereas the image-based pathway applies holistic templates to sensory input. Our experiments use rule-plus-exception structures in which one exception item in each category violates a salient regularity and must be distinguished from other items. In Experiment 1, we find that discrete representations are crucial for recognition of exceptions following brief training. Experiments 2 and 3 involve multi-session training regimens designed to encourage either part or image-based encoding. We find that both pathways are able to support exception encoding, but have unique characteristics. We speculate that one advantage of the part-based pathway is the ability to generalize across domains, whereas the image-based pathway provides faster and more effortless recognition. PMID:19460948
Wilson, F A; Rolls, E T
1993-01-01
The function of the amygdala in behavioural responses to novel stimuli and its possible function in recognition memory were investigated by recording the responses of 659 amygdaloid neurons in monkeys performing recognition memory and visual discrimination tasks. The aim was to determine the contribution of the amygdala in the encoding of familiarity and therefore its role in supporting memory-related neuronal mechanisms in the basal forebrain. The responses of three groups of neurons reflected different forms of memory. One group (n = 10) responded maximally to novel stimuli and significantly less so to the same stimuli when they were familiar. The calculated memory spans of these neurons were in the range of 2-10 intervening trials, and this short-term retention of information may reflect the operation of a neural mechanism encoding memory for the recency of stimulus presentation. Two other groups responded to the sight of particular categories of familiar stimuli: to foods (n = 6) or to faces (n = 10). The responses of some of these stimulus-selective neurons declined with repeated presentations of foods (3/4 tests) and faces (2/6 tests). The activity of these latter two groups of neurons may be involved in behavioural responses to familiar visual stimuli, particularly when such stimuli have affective or motivational significance. We conclude that the neurophysiological data provide evidence of amygdaloid mechanisms for the recognition of recently seen visual stimuli. However, these amygdaloid mechanisms do not appear to be sufficient to support the performance of long-term recognition memory tasks without additional and complementary functions carried out by other ventromedial temporal, prefrontal and diencephalic structures which also project to the basal forebrain.
McDonald, R J; Hong, N S
2004-01-01
This experiment tested the idea that the amygdala-based learning and memory system covertly acquires a stimulus-reward (stimulus-outcome) association during acquisition of a stimulus-response (S-R) habit task developed for the eight-arm radial maze. Groups of rats were given dorso-lateral striatal or amygdala lesions and then trained on the S-R habit task on the eight-arm radial maze. Rats with neurotoxic damage to the dorso-lateral striatum were severely impaired on the acquisition of the S-R habit task but showed a conditioned-cue preference for the stimulus reinforced during S-R habit training. Rats with neurotoxic damage to the amygdala were able to acquire the S-R habit task but did not show a conditioned-cue preference for the stimulus reinforced during S-R habit training. This pattern of results represents a dissociation of learning and memory functions of the dorsal striatum and amygdala on the same task.
Jiang, Ji-Mou; Lin, Yong-Xiang; Chen, Yi-Yong; Deng, Chao-Jun; Gong, Hui-Wen; Xu, Qi-Zhi; Zheng, Shao-Quan; Chen, Wei
2015-06-01
The objective of this work was to investigate why loquat fruit peels are more sensitive to high temperature and strong sunlight, making them highly susceptible to sunburn, during the color changing period (CCP). Two dimensional gel electrophoresis (2-DE) of the fruit peel proteins was performed over three developmental periods, namely green fruit period (GFP), color changing period and yellow ripening period (YRP). Fifty-five protein spots with at least 2-fold differences in abundance were successfully identified by MALDI-TOF-TOF/MS. The identified proteins were divided into categories related to heat-shock response, stress response and defense, energy metabolism, photosynthesis and protein biosynthesis. The results showed that expression of proteins related to anaerobic respiration and photorespiration were increased while the proteins related to ROS scavenging, polyamine biosynthesis, defense pathogens and photosynthesis were decreased during CCP under heat stress. Our findings provide new insights into the molecular mechanism of loquat fruit susceptible to sunburn during CCP. Copyright © 2014 Elsevier Ltd. All rights reserved.
Seno, Takeharu; Fukuda, Haruaki
2012-01-01
Over the last 100 years, numerous studies have examined the effective visual stimulus properties for inducing illusory self-motion (known as vection). This vection is often experienced more strongly in daily life than under controlled experimental conditions. One well-known example of vection in real life is the so-called 'train illusion'. In the present study, we showed that this train illusion can also be generated in the laboratory using virtual computer graphics-based motion stimuli. We also demonstrated that this vection can be modified by altering the meaning of the visual stimuli (i.e., top down effects). Importantly, we show that the semantic meaning of a stimulus can inhibit or facilitate vection, even when there is no physical change to the stimulus.
Mechanical low-frequency filter via modes separation in 3D periodic structures
D'Alessandro, L.; Belloni, E.; Ardito, R.; Braghin, F.; Corigliano, A.
2017-12-01
This work presents a strategy to design three-dimensional elastic periodic structures endowed with complete bandgaps, the first of which is ultra-wide, where the top limits of the first two bandgaps are overstepped in terms of wave transmission in the finite structure. Thus, subsequent bandgaps are merged, approaching the behaviour of a three-dimensional low-pass mechanical filter. This result relies on a proper organization of the modal characteristics, and it is validated by performing numerical and analytical calculations over the unit cell. A prototype of the analysed layout, made of Nylon by means of additive manufacturing, is experimentally tested to assess the transmission spectrum of the finite structure, obtaining good agreement with numerical predictions. The presented strategy paves the way for the development of a class of periodic structures to be used in robust and reliable wave attenuation over a wide frequency band.
Cappaert, N.L.M.; Ramekers, D.; Martens, H.C.F.; Wadman, W.J.
2013-01-01
Most deep brain stimulators apply rectangular monophasic voltage pulses. By modifying the stimulus shape, it is possible to optimize stimulus efficacy and find the best compromise between clinical effect, minimal side effects and power consumption of the stimulus generator. In this study, we
Bullock, Christopher E.; Myers, Todd M.
2009-01-01
Acquisition and maintenance of touch-screen responding was examined in naive cynomolgus monkeys ("Macaca fascicularis") under automaintenance and classical conditioning arrangements. In the first condition of Experiment 1, we compared acquisition of screen touching to a randomly positioned stimulus (a gray square) that was either stationary or…
Size matters: Perceived depth magnitude varies with stimulus height.
Tsirlin, Inna; Wilcox, Laurie M; Allison, Robert S
2016-06-01
Both the upper and lower disparity limits for stereopsis vary with the size of the targets. Recently, Tsirlin, Wilcox, and Allison (2012) suggested that perceived depth magnitude from stereopsis might also depend on the vertical extent of a stimulus. To test this hypothesis we compared apparent depth in small discs to depth in long bars with equivalent width and disparity. We used three estimation techniques: a virtual ruler, a touch-sensor (for haptic estimates) and a disparity probe. We found that depth estimates were significantly larger for the bar stimuli than for the disc stimuli for all methods of estimation and different configurations. In a second experiment, we measured perceived depth as a function of the height of the bar and the radius of the disc. Perceived depth increased with increasing bar height and disc radius suggesting that disparity is integrated along the vertical edges. We discuss size-disparity correlation and inter-neural excitatory connections as potential mechanisms that could account for these results. Copyright © 2016 Elsevier Ltd. All rights reserved.
Neuronal representations of stimulus associations develop in the temporal lobe during learning
Messinger, Adam; Squire, Larry R.; Zola, Stuart M.; Albright, Thomas D.
2001-01-01
Visual stimuli that are frequently seen together become associated in long-term memory, such that the sight of one stimulus readily brings to mind the thought or image of the other. It has been hypothesized that acquisition of such long-term associative memories proceeds via the strengthening of connections between neurons representing the associated stimuli, such that a neuron initially responding only to one stimulus of an associated pair eventually comes to respond to both. Consistent with...
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Julie M. Bugg
2012-09-01
Full Text Available Cognitive control is by now a large umbrella term referring collectively to multiple processes that plan and coordinate actions to meet task goals. A common feature of paradigms that engage cognitive control is the task requirement to select relevant information despite a habitual tendency (or bias to select goal-irrelevant information. At least since the 70s, researchers have employed proportion congruent manipulations to experimentally establish selection biases and evaluate the mechanisms used to control attention. Proportion congruent manipulations vary the frequency with which irrelevant information conflicts (i.e., is incongruent with relevant information. The purpose of this review is to summarize the growing body of literature on proportion congruent effects across selective attention paradigms, beginning first with Stroop, and then describing parallel effects in flanker and task-switching paradigms. The review chronologically tracks the expansion of the proportion congruent manipulation from its initial implementation at the list-wide level, to more recent implementations at the item-specific and context-specific levels. An important theoretical aim is demonstrating that proportion congruent effects at different levels (e.g., list-wide vs. item or context-specific support a distinction between voluntary forms of cognitive control, which operate based on anticipatory information, and relatively automatic or reflexive forms of cognitive control, which are rapidly triggered by the processing of particular stimuli or stimulus features. A further aim is to highlight those proportion congruent manipulations that allow researchers to dissociate stimulus-driven control from other stimulus-driven processes (e.g., S-R responding; episodic retrieval. We conclude by discussing the utility of proportion congruent manipulations for exploring the distinction between voluntary control and stimulus-driven control in other relevant paradigms.
Activity-dependent astrocyte swelling is mediated by pH-regulating mechanisms.
Larsen, Brian Roland; MacAulay, Nanna
2017-10-01
During neuronal activity in the mammalian brain, the K + released into the synaptic space is initially buffered by the astrocytic compartment. In parallel, the extracellular space (ECS) shrinks, presumably due to astrocytic cell swelling. With the Na + /K + /2Cl - cotransporter and the Kir4.1/AQP4 complex not required for the astrocytic cell swelling in the hippocampus, the molecular mechanisms underlying the activity-dependent ECS shrinkage have remained unresolved. To identify these molecular mechanisms, we employed ion-sensitive microelectrodes to measure changes in ECS, [K + ] o and [H + ] o /pH o during electrical stimulation of rat hippocampal slices. Transporters and receptors responding directly to the K + and glutamate released into the extracellular space (the K + /Cl - cotransporter, KCC, glutamate transporters and G protein-coupled receptors) did not modulate the extracellular space dynamics. The HCO3--transporting mechanism, which in astrocytes mainly constitutes the electrogenic Na + / HCO3- cotransporter 1 (NBCe1), is activated by the K + -mediated depolarization of the astrocytic membrane. Inhibition of this transporter reduced the ECS shrinkage by ∼25% without affecting the K + transients, pointing to NBCe1 as a key contributor to the stimulus-induced astrocytic cell swelling. Inhibition of the monocarboxylate cotransporters (MCT), like-wise, reduced the ECS shrinkage by ∼25% without compromising the K + transients. Isosmotic reduction of extracellular Cl - revealed a requirement for this ion in parts of the ECS shrinkage. Taken together, the stimulus-evoked astrocytic cell swelling does not appear to occur as a direct effect of the K + clearance, as earlier proposed, but partly via the pH-regulating transport mechanisms activated by the K + -induced astrocytic depolarization and the activity-dependent metabolism. © 2017 Wiley Periodicals, Inc.
The 5-HT1A Receptor and the Stimulus Effects of LSD in the Rat
Reissig, C.J.; Eckler, J.R.; Rabin, R.A.; Winter, J.C.
2005-01-01
Rationale It has been suggested that the 5-HT1A receptor plays a significant modulatory role in the stimulus effects of the indoleamine hallucinogen lysergic acid diethylamide (LSD). Objectives The present study sought to characterize the effects of several compounds with known affinity for the 5-HT1A receptor on the discriminative stimulus effects of LSD. Methods 12 Male F-344 rats were trained in a two-lever, fixed ratio10, food reinforced task with LSD (0.1 mg/kg; IP; 15 min pretreatment) as a discriminative stimulus. Combination and substitution tests with the 5-HT1A agonists, 8-OH-DPAT, buspirone, gepirone, and ipsapirone, with LSD-induced stimulus control were then performed. The effects of these 5-HT1A ligands were also tested in the presence of the selective 5-HT1A receptor antagonist, WAY-100,635 (0.3 mg/kg; SC; 30 min. pretreatment). Results In combination tests stimulus control by LSD was increased by all 5-HT1A receptor ligands with agonist properties. Similarly, in tests of antagonism, the increase in drug-appropriate responding caused by stimulation of the 5-HT1A receptor was abolished by administration of WAY-100,635. Conclusions These data, obtained using a drug discrimination model of the hallucinogenic effects of LSD, provide support for the hypothesis that the 5-HT1A receptor has a significant modulatory role in the stimulus effects of LSD. PMID:16025319
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Rachel L Beattie
Full Text Available We examined whether the characteristic impairments of dyslexia are due to a deficit in excluding external noise or a deficit in taking advantage of repeated stimulus presentation. We compared non-impaired adults and adults with poor reading performance on a visual letter detection task that varied two aspects: the presence or absence of background visual noise, and a small or large stimulus set. There was no interaction between group and stimulus set size, indicating that the poor readers took advantage of repeated stimulus presentation as well as the non-impaired readers. The poor readers had higher thresholds than non-impaired readers in the presence of high external noise, but not in the absence of external noise. The results support the hypothesis that an external noise exclusion deficit, not a perceptual anchoring deficit, impairs reading for adults.
Piray, Payam; Zeighami, Yashar; Bahrami, Fariba; Eissa, Abeer M; Hewedi, Doaa H; Moustafa, Ahmed A
2014-06-04
A substantial subset of Parkinson's disease (PD) patients suffers from impulse control disorders (ICDs), which are side effects of dopaminergic medication. Dopamine plays a key role in reinforcement learning processes. One class of reinforcement learning models, known as the actor-critic model, suggests that two components are involved in these reinforcement learning processes: a critic, which estimates values of stimuli and calculates prediction errors, and an actor, which estimates values of potential actions. To understand the information processing mechanism underlying impulsive behavior, we investigated stimulus and action value learning from reward and punishment in four groups of participants: on-medication PD patients with ICD, on-medication PD patients without ICD, off-medication PD patients without ICD, and healthy controls. Analysis of responses suggested that participants used an actor-critic learning strategy and computed prediction errors based on stimulus values rather than action values. Quantitative model fits also revealed that an actor-critic model of the basal ganglia with different learning rates for positive and negative prediction errors best matched the choice data. Moreover, whereas ICDs were associated with model parameters related to stimulus valuation (critic), PD was associated with parameters related to action valuation (actor). Specifically, PD patients with ICD exhibited lower learning from negative prediction errors in the critic, resulting in an underestimation of adverse consequences associated with stimuli. These findings offer a specific neurocomputational account of the nature of compulsive behaviors induced by dopaminergic drugs. Copyright © 2014 the authors 0270-6474/14/347814-11$15.00/0.
Tsatsishvili, Valeri; Burunat, Iballa; Cong, Fengyu; Toiviainen, Petri; Alluri, Vinoo; Ristaniemi, Tapani
2018-06-01
There has been growing interest towards naturalistic neuroimaging experiments, which deepen our understanding of how human brain processes and integrates incoming streams of multifaceted sensory information, as commonly occurs in real world. Music is a good example of such complex continuous phenomenon. In a few recent fMRI studies examining neural correlates of music in continuous listening settings, multiple perceptual attributes of music stimulus were represented by a set of high-level features, produced as the linear combination of the acoustic descriptors computationally extracted from the stimulus audio. NEW METHOD: fMRI data from naturalistic music listening experiment were employed here. Kernel principal component analysis (KPCA) was applied to acoustic descriptors extracted from the stimulus audio to generate a set of nonlinear stimulus features. Subsequently, perceptual and neural correlates of the generated high-level features were examined. The generated features captured musical percepts that were hidden from the linear PCA features, namely Rhythmic Complexity and Event Synchronicity. Neural correlates of the new features revealed activations associated to processing of complex rhythms, including auditory, motor, and frontal areas. Results were compared with the findings in the previously published study, which analyzed the same fMRI data but applied linear PCA for generating stimulus features. To enable comparison of the results, methodology for finding stimulus-driven functional maps was adopted from the previous study. Exploiting nonlinear relationships among acoustic descriptors can lead to the novel high-level stimulus features, which can in turn reveal new brain structures involved in music processing. Copyright © 2018 Elsevier B.V. All rights reserved.
Flexible goal imitation: Vicarious feedback influences stimulus-response binding by observation.
Giesen, Carina; Scherdin, Kerstin; Rothermund, Klaus
2017-06-01
This study investigated whether vicarious feedback influences binding processes between stimuli and observed responses. Two participants worked together in a shared color categorization task, taking the roles of actor and observer in turns. During a prime trial, participants saw a word while observing the other person executing a specific response. Automatic binding of words and observed responses into stimulus-response (S-R) episodes was assessed via word repetition effects in a subsequent probe trial in which either the same (compatible) or a different (incompatible) response had to be executed by the participants in response to the same or a different word. Results showed that vicarious prime feedback (i.e., the feedback that the other participant received for her or his response in the prime) modulated S-R retrieval effects: After positive vicarious prime feedback, typical S-R retrieval effects emerged (i.e., performance benefits for stimulus repetition probes with compatible responses, but performance costs for stimulus repetition probes with incompatible responses emerged). Notably, however, S-R-retrieval effects were reversed after vicarious negative prime feedback (meaning that stimulus repetition in the probe resulted in performance costs if prime and probe responses were compatible, and in performance benefits for incompatible responses). Findings are consistent with a flexible goal imitation account, according to which imitation is based on an interpretative and therefore feedback-sensitive reconstruction of action goals from observed movements. In concert with earlier findings, this data support the conclusion that transient S-R binding and retrieval processes are involved in social learning phenomena.
Changes in stimulus and response AC/A ratio with vision therapy in Convergence Insufficiency.
Singh, Neeraj Kumar; Mani, Revathy; Hussaindeen, Jameel Rizwana
To evaluate the changes in the stimulus and response Accommodative Convergence to Accommodation (AC/A) ratio following vision therapy (VT) in Convergence Insufficiency (CI). Stimulus and response AC/A ratio were measured on twenty five CI participants, pre and post 10 sessions of VT. Stimulus AC/A ratio was measured using the gradient method and response AC/A ratio was calculated using modified Thorington technique with accommodative responses measured using WAM-5500 open-field autorefractor. The gradient stimulus and response AC/A cross-link ratios were compared with thirty age matched controls. Mean age of the CI and control participants were 23.3±5.2 years and 22.7±4.2 years, respectively. The mean stimulus and response AC/A ratio for CI pre therapy was 2.2±0.72 and 6.3±2.0 PD/D that changed to 4.2±0.9 and 8.28±3.31 PD/D respectively post vision therapy and these changes were statistically significant (paired t-test; paccommodation parameters in subjects with convergence insufficiency. This represents the plasticity of the AC/A crosslink ratios that could be achieved with vision therapy in CI. Copyright © 2016 Spanish General Council of Optometry. Published by Elsevier España, S.L.U. All rights reserved.
Pyff - a pythonic framework for feedback applications and stimulus presentation in neuroscience.
Venthur, Bastian; Scholler, Simon; Williamson, John; Dähne, Sven; Treder, Matthias S; Kramarek, Maria T; Müller, Klaus-Robert; Blankertz, Benjamin
2010-01-01
This paper introduces Pyff, the Pythonic feedback framework for feedback applications and stimulus presentation. Pyff provides a platform-independent framework that allows users to develop and run neuroscientific experiments in the programming language Python. Existing solutions have mostly been implemented in C++, which makes for a rather tedious programming task for non-computer-scientists, or in Matlab, which is not well suited for more advanced visual or auditory applications. Pyff was designed to make experimental paradigms (i.e., feedback and stimulus applications) easily programmable. It includes base classes for various types of common feedbacks and stimuli as well as useful libraries for external hardware such as eyetrackers. Pyff is also equipped with a steadily growing set of ready-to-use feedbacks and stimuli. It can be used as a standalone application, for instance providing stimulus presentation in psychophysics experiments, or within a closed loop such as in biofeedback or brain-computer interfacing experiments. Pyff communicates with other systems via a standardized communication protocol and is therefore suitable to be used with any system that may be adapted to send its data in the specified format. Having such a general, open-source framework will help foster a fruitful exchange of experimental paradigms between research groups. In particular, it will decrease the need of reprogramming standard paradigms, ease the reproducibility of published results, and naturally entail some standardization of stimulus presentation.
Source memory that encoding was self-referential: the influence of stimulus characteristics.
Durbin, Kelly A; Mitchell, Karen J; Johnson, Marcia K
2017-10-01
Decades of research suggest that encoding information with respect to the self improves memory (self-reference effect, SRE) for items (item SRE). The current study focused on how processing information in reference to the self affects source memory for whether an item was self-referentially processed (a source SRE). Participants self-referentially or non-self-referentially encoded words (Experiment 1) or pictures (Experiment 2) that varied in valence (positive, negative, neutral). Relative to non-self-referential processing, self-referential processing enhanced item recognition for all stimulus types (an item SRE), but it only enhanced source memory for positive words (a source SRE). In fact, source memory for negative and neutral pictures was worse for items processed self-referentially than non-self-referentially. Together, the results suggest that item SRE and source SRE (e.g., remembering an item was encoded self-referentially) are not necessarily the same across stimulus types (e.g., words, pictures; positive, negative). While an item SRE may depend on the overall likelihood the item generates any association, the enhancing effects of self-referential processing on source memory for self-referential encoding may depend on how embedded a stimulus becomes in one's self-schema, and that depends, in part, on the stimulus' valence and format. Self-relevance ratings during encoding provide converging evidence for this interpretation.
Stimulus-specific variability in color working memory with delayed estimation.
Bae, Gi-Yeul; Olkkonen, Maria; Allred, Sarah R; Wilson, Colin; Flombaum, Jonathan I
2014-04-08
Working memory for color has been the central focus in an ongoing debate concerning the structure and limits of visual working memory. Within this area, the delayed estimation task has played a key role. An implicit assumption in color working memory research generally, and delayed estimation in particular, is that the fidelity of memory does not depend on color value (and, relatedly, that experimental colors have been sampled homogeneously with respect to discriminability). This assumption is reflected in the common practice of collapsing across trials with different target colors when estimating memory precision and other model parameters. Here we investigated whether or not this assumption is secure. To do so, we conducted delayed estimation experiments following standard practice with a memory load of one. We discovered that different target colors evoked response distributions that differed widely in dispersion and that these stimulus-specific response properties were correlated across observers. Subsequent experiments demonstrated that stimulus-specific responses persist under higher memory loads and that at least part of the specificity arises in perception and is eventually propagated to working memory. Posthoc stimulus measurement revealed that rendered stimuli differed from nominal stimuli in both chromaticity and luminance. We discuss the implications of these deviations for both our results and those from other working memory studies.
Geran, Laura; Travers, Susan
2013-01-01
It has been demonstrated that temporal features of spike trains can increase the amount of information available for gustatory processing. However, the nature of these temporal characteristics and their relationship to different taste qualities and neuron types are not well-defined. The present study analyzed the time course of taste responses from parabrachial (PBN) neurons elicited by multiple applications of "sweet" (sucrose), "salty" (NaCl), "sour" (citric acid), and "bitter" (quinine and cycloheximide) stimuli in an acute preparation. Time course varied significantly by taste stimulus and best-stimulus classification. Across neurons, the ensemble code for the three electrolytes was similar initially but quinine diverged from NaCl and acid during the second 500 ms of stimulation and all four qualities became distinct just after 1s. This temporal evolution was reflected in significantly broader tuning during the initial response. Metric space analyses of quality discrimination by individual neurons showed that increases in information (H) afforded by temporal factors was usually explained by differences in rate envelope, which had a greater impact during the initial 2s (22.5% increase in H) compared to the later response (9.5%). Moreover, timing had a differential impact according to cell type, with between-quality discrimination in neurons activated maximally by NaCl or citric acid most affected. Timing was also found to dramatically improve within-quality discrimination (80% increase in H) in neurons that responded optimally to bitter stimuli (B-best). Spikes from B-best neurons were also more likely to occur in bursts. These findings suggest that among PBN taste neurons, time-dependent increases in mutual information can arise from stimulus- and neuron-specific differences in response envelope during the initial dynamic period. A stable rate code predominates in later epochs.
The role of the right superior temporal gyrus in stimulus-centered spatial processing.
Shah-Basak, Priyanka P; Chen, Peii; Caulfield, Kevin; Medina, Jared; Hamilton, Roy H
2018-05-01
Although emerging neuropsychological evidence supports the involvement of temporal areas, and in particular the right superior temporal gyrus (STG), in allocentric neglect deficits, the role of STG in healthy spatial processing remains elusive. While several functional brain imaging studies have demonstrated involvement of the STG in tasks involving explicit stimulus-centered judgments, prior rTMS studies targeting the right STG did not find the expected neglect-like rightward bias in size judgments using the conventional landmark task. The objective of the current study was to investigate whether disruption of the right STG using inhibitory repetitive transcranial magnetic stimulation (rTMS) could impact stimulus-centered, allocentric spatial processing in healthy individuals. A lateralized version of the landmark task was developed to accentuate the dissociation between viewer-centered and stimulus-centered reference frames. We predicted that inhibiting activity in the right STG would decrease accuracy because of induced rightward bias centered on the line stimulus irrespective of its viewer-centered or egocentric locations. Eleven healthy, right-handed adults underwent the lateralized landmark task. After viewing each stimulus, participants had to judge whether the line was bisected, or whether the left (left-long trials) or the right segment (right-long trials) of the line was longer. Participants repeated the task before (pre-rTMS) and after (post-rTMS) receiving 20 min of 1 Hz rTMS over the right STG, the right supramarginal gyrus (SMG), and the vertex (a control site) during three separate visits. Linear mixed models for binomial data were generated with either accuracy or judgment errors as dependent variables, to compare 1) performance across trial types (bisection, non-bisection), and 2) pre- vs. post-rTMS performance between the vertex and the STG and the vertex and the SMG. Line eccentricity (z = 4.31, p right-long type by 10.7% on bisection
Studies of phase return map and symbolic dynamics in a periodically driven Hodgkin—Huxley neuron
International Nuclear Information System (INIS)
Ding Jiong; Zhang Hong; Tong Qin-Ye; Chen Zhuo
2014-01-01
How neuronal spike trains encode external information is a hot topic in neurodynamics studies. In this paper, we investigate the dynamical states of the Hodgkin—Huxley neuron under periodic forcing. Depending on the parameters of the stimulus, the neuron exhibits periodic, quasiperiodic and chaotic spike trains. In order to analyze these spike trains quantitatively, we use the phase return map to describe the dynamical behavior on a one-dimensional (1D) map. According to the monotonicity or discontinuous point of the 1D map, the spike trains are transformed into symbolic sequences by implementing a coarse-grained algorithm — symbolic dynamics. Based on the ordering rules of symbolic dynamics, the parameters of the external stimulus can be measured in high resolution with finite length symbolic sequences. A reasonable explanation for why the nervous system can discriminate or cognize the small change of the external signals in a short time is also presented. (general)
Simpson, Claire; Pinkham, Amy E; Kelsven, Skylar; Sasson, Noah J
2013-12-01
Emotion can be expressed by both the voice and face, and previous work suggests that presentation modality may impact emotion recognition performance in individuals with schizophrenia. We investigated the effect of stimulus modality on emotion recognition accuracy and the potential role of visual attention to faces in emotion recognition abilities. Thirty-one patients who met DSM-IV criteria for schizophrenia (n=8) or schizoaffective disorder (n=23) and 30 non-clinical control individuals participated. Both groups identified emotional expressions in three different conditions: audio only, visual only, combined audiovisual. In the visual only and combined conditions, time spent visually fixating salient features of the face were recorded. Patients were significantly less accurate than controls in emotion recognition during both the audio and visual only conditions but did not differ from controls on the combined condition. Analysis of visual scanning behaviors demonstrated that patients attended less than healthy individuals to the mouth in the visual condition but did not differ in visual attention to salient facial features in the combined condition, which may in part explain the absence of a deficit for patients in this condition. Collectively, these findings demonstrate that patients benefit from multimodal stimulus presentations of emotion and support hypotheses that visual attention to salient facial features may serve as a mechanism for accurate emotion identification. © 2013.
The Primary Visual Cortex Is Differentially Modulated by Stimulus-Driven and Top-Down Attention
Bekisz, Marek; Bogdan, Wojciech; Ghazaryan, Anaida; Waleszczyk, Wioletta J.; Kublik, Ewa; Wróbel, Andrzej
2016-01-01
Selective attention can be focused either volitionally, by top-down signals derived from task demands, or automatically, by bottom-up signals from salient stimuli. Because the brain mechanisms that underlie these two attention processes are poorly understood, we recorded local field potentials (LFPs) from primary visual cortical areas of cats as they performed stimulus-driven and anticipatory discrimination tasks. Consistent with our previous observations, in both tasks, we found enhanced beta activity, which we have postulated may serve as an attention carrier. We characterized the functional organization of task-related beta activity by (i) cortical responses (EPs) evoked by electrical stimulation of the optic chiasm and (ii) intracortical LFP correlations. During the anticipatory task, peripheral stimulation that was preceded by high-amplitude beta oscillations evoked large-amplitude EPs compared with EPs that followed low-amplitude beta. In contrast, during the stimulus-driven task, cortical EPs preceded by high-amplitude beta oscillations were, on average, smaller than those preceded by low-amplitude beta. Analysis of the correlations between the different recording sites revealed that beta activation maps were heterogeneous during the bottom-up task and homogeneous for the top-down task. We conclude that bottom-up attention activates cortical visual areas in a mosaic-like pattern, whereas top-down attentional modulation results in spatially homogeneous excitation. PMID:26730705
Peltz, Cathryn D; Sarver, Joseph J; Dourte, Leann M; Würgler-Hauri, Carola C; Williams, Gerald R; Soslowsky, Louis J
2010-07-01
Rotator cuff tears are a common clinical problem that can result in pain and disability. Previous studies in a rat model showed enhanced tendon to bone healing with postoperative immobilization. The objective of this study was to determine the effect of postimmobilization activity level on insertion site properties and joint mechanics in a rat model. Our hypothesis was that exercise following a short period of immobilization will cause detrimental changes in insertion site properties compared to cage activity following the same period of immobilization, but that passive shoulder mechanics will not be affected. We detached and repaired the supraspinatus tendon of 22 Sprague-Dawley rats, and the injured shoulder was immobilized postoperatively for 2 weeks. Following immobilization, rats were prescribed cage activity or exercise for 12 weeks. Passive shoulder mechanics were determined, and following euthanasia, tendon cross-sectional area and mechanical properties were measured. Exercise following immobilization resulted in significant decreases compared to cage activity in range of motion, tendon stiffness, modulus, percent relaxation, and several parameters from both a structurally based elastic model and a quasi-linear viscoelastic model. Therefore, we conclude that after a short period of immobilization, increased activity is detrimental to both tendon mechanical properties and shoulder joint mechanics, presumably due to increased scar production. (c) 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc
de Groot, Annette M. B.
2006-01-01
This study examined the effects of three stimulus variables and background music on paired-associate learning of foreign language (FL) vocabulary. The stimulus variables were the frequency and concreteness of the native language (L1) words and the (phonotactical) typicality of the FL words. Sixty-four L1-FL pairs were presented for learning six…
Once on the Lips, Forever on the Hips: A Benefit-Cost Analysis of Fiscal Stimulus in OECD Countries
Bev Dahlby
2009-01-01
The author evaluates the fiscal stimulus policies of 20 OECD countries within a simple benefit-cost framework. Among his findings: in Canada, to be justifiable on a benefit-cost basis, a fiscal stimulus project that improves consumptive public services must provide at least 73 cents in benefits for every dollar of fiscal stimulus.
Troisi, Joseph R., II
2006-01-01
To date, only 1 study has evaluated the impact of a Pavlovian drug conditional stimulus (CS) on operant responding. A within-subject operant 1-lever go/no-go (across sessions) design was used to evaluate the impact of Pavlovian contingencies on the discriminative stimulus effects of nicotine (0.4 mg/kg) and ethanol (800 mg/kg) in male Sprague…
Directory of Open Access Journals (Sweden)
Wuyin Jin
2017-01-01
Full Text Available The noise effects on a homeostatic regulation of sleep-wake cycles’ neuronal mathematical model determined by the hypocretin/orexin and the local glutamate interneurons spatiotemporal behaviors are studied within the neighborhood of stimulus threshold in this work; the neuronal noise added to the stimulus, the conductance, and the activation variable of the modulation function are investigated, respectively, based on a circadian input skewed in sine function. The computer simulation results suggested that the increased amplitude of external current input will lead to the fact that awakening time is advanced but the sleepy time remains the same; for the bigger conductance and modulation noise, the regulatory mechanism of the model sometimes will be collapsed and the coupled two neurons of the model show very irregular activities; the falling asleep or wake transform appears at nondeterminate time.
DEFF Research Database (Denmark)
Dicke, Ulrike; Ewert, Stephan D.; Dau, Torsten
2007-01-01
Periodic amplitude modulations AMs of an acoustic stimulus are presumed to be encoded in temporal activity patterns of neurons in the cochlear nucleus. Physiological recordings indicate that this temporal AM code is transformed into a rate-based periodicity code along the ascending auditory pathw...... accounts for the encoding of AM depth over a large dynamic range and for modulation frequency selective processing of complex sounds....
Zhu, Huiwen; Zhou, Yiming; Liu, Zhiyuan; Chen, Xi; Li, Yanqing; Liu, Xing; Ma, Lan
2018-01-01
Abstract Background Drug memories become labile and reconsolidated after retrieval by presentation of environmental cues (conditioned stimulus) or drugs (unconditioned stimulus). Whether conditioned stimulus and unconditioned stimulus retrieval trigger different memory reconsolidation processes is not clear. Methods Protein synthesis inhibitor or β-adrenergic receptor (β-AR) antagonist was systemically administrated or intra-central amygdala infused immediately after cocaine reexposure in cocaine-conditioned place preference or self-administration mice models. β-ARs were selectively knocked out in the central amygdala to further confirm the role of β-adrenergic receptor in cocaine reexposure-induced memory reconsolidation of cocaine-conditioned place preference. Results Cocaine reexposure triggered de novo protein synthesis dependent memory reconsolidation of cocaine-conditioned place preference. Cocaine-priming-induced reinstatement was also impaired with post cocaine retrieval manipulation, in contrast to the relapse behavior with post context retrieval manipulation. Cocaine retrieval, but not context retrieval, induced central amygdala activation. Protein synthesis inhibitor or β1-adrenergic receptor antagonist infused in the central amygdala after cocaine retrieval, but not context retrieval, inhibited memory reconsolidation and reinstatement. β1-adrenergic receptor knockout in the central amygdala suppressed cocaine retrieval-triggered memory reconsolidation and reinstatement of cocaine conditioned place preference. β1-adrenergic receptor antagonism after cocaine retrieval also impaired reconsolidation and reinstatement of cocaine self-administration. Conclusions Cocaine reward memory triggered by unconditioned stimulus retrieval is distinct from conditioned stimulus retrieval. Unconditioned stimulus retrieval induced reconsolidation of cocaine reward memory depends on β1-adrenergic signaling in the central amygdala. Post unconditioned stimulus
Hamm, Jordan P.; Bobilev, Anastasia M.; Hayrynen, Lauren K.; Hudgens-Haney, Matthew E.; Oliver, William T.; Parker, David A.; McDowell, Jennifer E.; Buckley, Peter A.; Clementz, Brett A.
2017-01-01
Electroencephalographic (EEG) studies of auditory steady-state responses (aSSRs) non-invasively probe gamma-band (40-Hz) oscillatory capacity in sensory cortex with high signal-to-noise ratio. Consistent reports of reduced 40-Hz aSSRs in persons with schizophrenia (SZ) indicate its potential as an efficient biomarker for the disease, but studies have been limited to passive or indirect listening contexts with stereotypically short (500ms) stimulus trains. An inability to modulate sensorineural processing in accord with behavioral goals or within the sensory environmental context may represent a fundamental deficit in SZ, but whether and how this deficit relates to reduced aSSRs is unknown. We systematically varied stimulus duration and attentional contexts to further mature the 40-Hz aSSR as biomarker for future translational or mechanistic studies. Eighteen SZ and 18 healthy subjects (H) were presented binaural pure-tones with or without sinusoidal amplitude modulation at 40-Hz. Stimulus duration (500-ms or 1500-ms) and attention (via a button press task) were varied across 4 separate blocks. Evoked potentials recorded with dense-array EEGs were analyzed in the time-frequency domain. SZ displayed reduced 40-Hz aSSRs to typical stimulation parameters, replicating previous findings. In H, aSSRs were reduced when stimuli were presented in longer trains and were slightly enhanced by attention. Only the former modulation was impaired in SZ and correlated with sensory discrimination performance. Thus, gamma-band aSSRs are modulated by both attentional and stimulus duration contexts, but only modulations related to physical stimulus properties are abnormal in SZ, supporting its status as a biomarker of psychotic perceptual disturbance involving non-attentional sensori-cortical circuits. PMID:25868936
Mechanism for boundary crises in quasiperiodically forced period-doubling systems
International Nuclear Information System (INIS)
Kim, Sang-Yoon; Lim, Woochang
2005-01-01
We investigate the mechanism for boundary crises in the quasiperiodically forced logistic map which is a representative model for quasiperiodically forced period-doubling systems. For small quasiperiodic forcing ε, a chaotic attractor disappears suddenly via a 'standard' boundary crisis when it collides with the smooth unstable torus. However, when passing a threshold value of ε, a basin boundary metamorphosis occurs, and then the smooth unstable torus is no longer accessible from the interior of the basin of the attractor. For this case, using the rational approximations to the quasiperiodic forcing, it is shown that a nonchaotic attractor (smooth torus or strange nonchaotic attractor) as well as a chaotic attractor is destroyed abruptly through a new type of boundary crisis when it collides with an invariant 'ring-shaped' unstable set which has no counterpart in the unforced case
Mechanism for boundary crises in quasiperiodically forced period-doubling systems
Energy Technology Data Exchange (ETDEWEB)
Kim, Sang-Yoon [Department of Physics, Kangwon National University, Chunchon, Kangwon-Do 200-701 (Korea, Republic of)]. E-mail: sykim@kangwon.ac.kr; Lim, Woochang [Department of Physics, Kangwon National University, Chunchon, Kangwon-Do 200-701 (Korea, Republic of)]. E-mail: wclim@kwnu.kangwon.ac.kr
2005-01-10
We investigate the mechanism for boundary crises in the quasiperiodically forced logistic map which is a representative model for quasiperiodically forced period-doubling systems. For small quasiperiodic forcing {epsilon}, a chaotic attractor disappears suddenly via a 'standard' boundary crisis when it collides with the smooth unstable torus. However, when passing a threshold value of {epsilon}, a basin boundary metamorphosis occurs, and then the smooth unstable torus is no longer accessible from the interior of the basin of the attractor. For this case, using the rational approximations to the quasiperiodic forcing, it is shown that a nonchaotic attractor (smooth torus or strange nonchaotic attractor) as well as a chaotic attractor is destroyed abruptly through a new type of boundary crisis when it collides with an invariant 'ring-shaped' unstable set which has no counterpart in the unforced case.
Stimulus-specific suppression preserves information in auditory short-term memory.
Linke, Annika C; Vicente-Grabovetsky, Alejandro; Cusack, Rhodri
2011-08-02
Philosophers and scientists have puzzled for millennia over how perceptual information is stored in short-term memory. Some have suggested that early sensory representations are involved, but their precise role has remained unclear. The current study asks whether auditory cortex shows sustained frequency-specific activation while sounds are maintained in short-term memory using high-resolution functional MRI (fMRI). Investigating short-term memory representations within regions of human auditory cortex with fMRI has been difficult because of their small size and high anatomical variability between subjects. However, we overcame these constraints by using multivoxel pattern analysis. It clearly revealed frequency-specific activity during the encoding phase of a change detection task, and the degree of this frequency-specific activation was positively related to performance in the task. Although the sounds had to be maintained in memory, activity in auditory cortex was significantly suppressed. Strikingly, patterns of activity in this maintenance period correlated negatively with the patterns evoked by the same frequencies during encoding. Furthermore, individuals who used a rehearsal strategy to remember the sounds showed reduced frequency-specific suppression during the maintenance period. Although negative activations are often disregarded in fMRI research, our findings imply that decreases in blood oxygenation level-dependent response carry important stimulus-specific information and can be related to cognitive processes. We hypothesize that, during auditory change detection, frequency-specific suppression protects short-term memory representations from being overwritten by inhibiting the encoding of interfering sounds.
A model for food and stimulus changes that signal time-based contingency changes.
Cowie, Sarah; Davison, Michael; Elliffe, Douglas
2014-11-01
When the availability of reinforcers depends on time since an event, time functions as a discriminative stimulus. Behavioral control by elapsed time is generally weak, but may be enhanced by added stimuli that act as additional time markers. The present paper assessed the effect of brief and continuous added stimuli on control by time-based changes in the reinforcer differential, using a procedure in which the local reinforcer ratio reversed at a fixed time after the most recent reinforcer delivery. Local choice was enhanced by the presentation of the brief stimuli, even when the stimulus change signalled only elapsed time, but not the local reinforcer ratio. The effect of the brief stimulus presentations on choice decreased as a function of time since the most recent stimulus change. We compared the ability of several versions of a model of local choice to describe these data. The data were best described by a model which assumed that error in discriminating the local reinforcer ratio arose from imprecise discrimination of reinforcers in both time and space, suggesting that timing behavior is controlled not only by discrimination elapsed time, but by discrimination of the reinforcer differential in time. © Society for the Experimental Analysis of Behavior.
van der Aa, J.; Honing, H.; ten Cate, C.
2015-01-01
Perceiving temporal regularity in an auditory stimulus is considered one of the basic features of musicality. Here we examine whether zebra finches can detect regularity in an isochronous stimulus. Using a go/no go paradigm we show that zebra finches are able to distinguish between an isochronous
Mechanical touch responses of Arabidopsis TCH1-3 mutant roots on inclined hard-agar surface
Zha, Guodong; Wang, Bochu; Liu, Junyu; Yan, Jie; Zhu, Liqing; Yang, Xingyan
2016-01-01
The gravity-induced mechanical touch stimulus can affect plant root architecture. Mechanical touch responses of plant roots are an important aspect of plant root growth and development. Previous studies have reported that Arabidopsis TCH1-3 genes are involved in mechano-related events, how-ever, the physiological functions of TCH1-3 genes in Arabidopsis root mechanoresponses remain unclear. In the present study, we applied an inclined hard agar plate method to produce mechanical touch stimulus, and provided evidence that altered mechanical environment could influence root growth. Furthermore, tch1-3 Arabidopsis mutants were investigated on inclined agar surfaces to explore the functions of TCH1-3 genes on Arabidopsis root mechanoresponses. The results showed that two tch2 mutants, cml24-2 and cml24-4, exhibited significantly reduced root length, biased skewing, and decreased density of lateral root. In addition, primary root length and density of lateral root of tch3 (cml12-2) was significantly decreased on inclined agar surfaces. This study indicates that the tch2 and tch3 mutants are hypersensitive to mechanical touch stimulus, and TCH2 (CML24-2 and CML24-4) and TCH3 (CML12-2) genes may participate in the mechanical touch response of Arabidopsis roots.
Continuous Flash Suppression: Stimulus Fractionation rather than Integration.
Moors, Pieter; Hesselmann, Guido; Wagemans, Johan; van Ee, Raymond
2017-10-01
Recent studies using continuous flash suppression suggest that invisible stimuli are processed as integrated, semantic entities. We challenge the viability of this account, given recent findings on the neural basis of interocular suppression and replication failures of high-profile CFS studies. We conclude that CFS reveals stimulus fractionation in visual cortex. Copyright © 2017 Elsevier Ltd. All rights reserved.
Directory of Open Access Journals (Sweden)
Yaqing eNiu
2012-09-01
Full Text Available In natural vision both stimulus features and cognitive/affective factors influence an observer's attention. However, the relationship between stimulus-driven (bottom-up and cognitive/affective (top-down factors remains controversial: Can affective salience counteract strong visual stimulus signals and shift attention allocation irrespective of bottom-up features? Is there any difference between negative and positive scenes in terms of their influence on attention deployment? Here we examined the impact of affective factors on eye movement behavior, to understand the competition between visual stimulus-driven salience and affective salience and how they affect gaze allocation in complex scene viewing. Building on our previous research, we compared predictions generated by a visual salience model with measures indexing participant-identified emotionally meaningful regions of each image. To examine how eye movement behaviour differs for negative, positive, and neutral scenes, we examined the influence of affective salience in capturing attention according to emotional valence. Taken together, our results show that affective salience can override stimulus-driven salience and overall emotional valence can determine attention allocation in complex scenes. These findings are consistent with the hypothesis that cognitive/affective factors play a dominant role in active gaze control.
Complex discriminative stimulus properties of (+)lysergic acid diethylamide (LSD) in C57Bl/6J mice.
Benneyworth, Michael A; Smith, Randy L; Barrett, Robert J; Sanders-Bush, Elaine
2005-06-01
The drug discrimination procedure is the most frequently used in vivo model of hallucinogen activity. Historically, most drug discrimination studies have been conducted in the rat. With the development of genetically modified mice, a powerful new tool has become available for investigating the mechanisms of drug-induced behavior. The current paper is part of an ongoing effort to determine the utility of the drug discrimination technique for evaluating hallucinogenic drugs in mice. To establish the training procedures and characterize the stimulus properties of (+)lysergic acid diethylamide (LSD) in mice. Using a two-lever drug discrimination procedure, C57Bl/6J mice were trained to discriminate 0.45 mg/kg LSD vs saline on a VI30 sec schedule of reinforcement, with vanilla-flavored Ensure serving as the reinforcer. As in rats, acquisition was orderly, but the training dose was nearly five-fold higher for mice than rats. LSD lever selection was dose-dependent. Time-course studies revealed a rapid loss of the LSD stimulus effects. The 5-HT(2A/2C) receptor agonist, 2,5-dimethoxy-4-bromoamphetamine [(-)DOB] (1.0 mg/kg), substituted fully for LSD and the 5-HT(1A) receptor agonist, 8-hydroxy-2-(di-n-propylamino)-tetralin (8-OH-DPAT) (1.6 mg/kg), substituted partially for LSD. Pretreatment with the 5-HT(2A) receptor-selective antagonist, MDL 100907, or the 5-HT(1A)-selective antagonist WAY 100635, showed that each antagonist only partially blocked LSD discrimination. Substitution of 1.0 mg/kg (-)DOB for LSD was fully blocked by pretreatment with MDL 100907 but unaltered by WAY 100635 pretreatment. These data suggest that in mice the stimulus effects of LSD have both a 5-HT(2A) receptor and a 5-HT(1A) receptor component.
Takigami, Satoshi; Sunada, Hiroshi; Lukowiak, Ken; Sakakibara, Manabu
2013-10-25
A new and better taste avoidance conditioning paradigm for Lymnaea has been developed that replaces the previously used tactile unconditional stimulus (US) with an brief electrical stimulus (1000V, 80μA), while continuing to use a sucrose application to the lips as the conditional stimulus (CS). With 15 paired CS-US presentations on a single day, we were able to elicit both short-term memory (STM) and long-term memory (LTM). The LTM persisted for at least one week. While STM was elicited with 5, 8, or 10 paired presentations of the CS-US on a single day, LTM was not. The new US used here was more consistent than the previously used US, and this stimulus consistency may explain why 15 paired CS-US presentations now result in LTM formation. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.
The role of stimulus-specific adaptation in songbird syntax generation
Wittenbach, Jason D.
Sequential behaviors are an important part of the behavioral repertoire of many animals and understanding how neural circuits encode and generate such sequences is a long-standing question in neuroscience. The Bengalese finch is a useful model system for studying variable action sequences. The songs of these birds consist of well-defined vocal elements (syllables) that are strung together to form sequences. The ordering of the syllables within the sequence is variable but not random - it shows complex statistical patterns (syntax). While often thought to be first-order, the syntax of the Bengalese finch song shows a distinct form of history dependence where the probability of repeating a syllable decreases as a function of the number of repetitions that have already occurred. Current models of the Bengalese finch song control circuitry offer no explanation for this repetition adaptation. The Bengalese finch also uses real-time auditory feedback to control the song syntax. Considering these facts, we hypothesize that repetition adaptation in the Bengalese finch syntax may be caused by stimulus-specific adaptation - a wide-spread phenomenon where neural responses to a specific stimulus become weaker with repeated presentations of the same stimulus. We begin by proposing a computational model for the song-control circuit where an auditory feedback signal that undergoes stimulus-specific adaptation helps drive repeated syllables. We show that this model does indeed capture the repetition adaptation observed in Bengalese finch syntax; along the way, we derive a new probabilistic model for repetition adaptation. Key predictions of our model are analyzed in light of experiments performed by collaborators. Next we extend the model in order to predict how the syntax will change as a function of brain temperature. These predictions are compared to experimental results from collaborators where portions of the Bengalese finch song circuit are cooled in awake and behaving birds
Stimulus threat and exposure context modulate the effect of mere exposure on approach behaviors
Directory of Open Access Journals (Sweden)
Steven Young
2016-11-01
Full Text Available Mere-exposure research has found that initially neutral objects made familiar are preferred relative to novel objects. Recent work extends these preference judgments into the behavioral domain by illustrating that mere exposure prompts approach-oriented behavior toward familiar stimuli. However, no investigations have examined the effect of mere exposure on approach-oriented behavior toward threatening stimuli. The current work examines this issue and also explores how exposure context interacts with stimulus threat to influence behavioral tendencies. In two experiments participants were presented with both mere-exposed and novel stimuli and approach speed was assessed. In the first experiment, when stimulus threat was presented in a homogeneous format (i.e., participants viewed exclusively neutral or threatening stimuli, mere-exposure potentiated approach behaviors for both neutral and threatening stimuli. However, in the second experiment, in which stimulus threat was presented in a heterogeneous fashion (i.e., participants viewed both neutral and threatening stimuli, mere exposure facilitated approach only for initially neutral stimuli. These results suggest that mere-exposure effects on approach behaviors are highly context sensitive and depend on both stimulus valence and exposure context. Further implications of these findings for the mere-exposure literature are discussed.
Stimulus Threat and Exposure Context Modulate the Effect of Mere Exposure on Approach Behaviors.
Young, Steven G; Jones, Isaiah F; Claypool, Heather M
2016-01-01
Mere-exposure (ME) research has found that initially neutral objects made familiar are preferred relative to novel objects. Recent work extends these preference judgments into the behavioral domain by illustrating that mere exposure prompts approach-oriented behavior toward familiar stimuli. However, no investigations have examined the effect of mere exposure on approach-oriented behavior toward threatening stimuli. The current work examines this issue and also explores how exposure context interacts with stimulus threat to influence behavioral tendencies. In two experiments participants were presented with both mere-exposed and novel stimuli and approach speed was assessed. In the first experiment, when stimulus threat was presented in a homogeneous format (i.e., participants viewed exclusively neutral or threatening stimuli), ME potentiated approach behaviors for both neutral and threatening stimuli. However, in the second experiment, in which stimulus threat was presented in a heterogeneous fashion (i.e., participants viewed both neutral and threatening stimuli), mere exposure facilitated approach only for initially neutral stimuli. These results suggest that ME effects on approach behaviors are highly context sensitive and depend on both stimulus valence and exposure context. Further implications of these findings for the ME literature are discussed.
te Woerd, Erik S; Oostenveld, Robert; Bloem, Bastiaan R; de Lange, Floris P; Praamstra, Peter
2015-01-01
The basal ganglia play an important role in beat perception and patients with Parkinson's disease (PD) are impaired in perception of beat-based rhythms. Rhythmic cues are nonetheless beneficial in gait rehabilitation, raising the question how rhythm improves movement in PD. We addressed this question with magnetoencephalography recordings during a choice response task with rhythmic and non-rhythmic modes of stimulus presentation. Analyses focused on (i) entrainment of slow oscillations, (ii) the depth of beta power modulation, and (iii) whether a gain in modulation depth of beta power, due to rhythmicity, is of predictive or reactive nature. The results show weaker phase synchronisation of slow oscillations and a relative shift from predictive to reactive movement-related beta suppression in PD. Nonetheless, rhythmic stimulus presentation increased beta modulation depth to the same extent in patients and controls. Critically, this gain selectively increased the predictive and not reactive movement-related beta power suppression. Operation of a predictive mechanism, induced by rhythmic stimulation, was corroborated by a sensory gating effect in the sensorimotor cortex. The predictive mode of cue utilisation points to facilitation of basal ganglia-premotor interactions, contrasting with the popular view that rhythmic stimulation confers a special advantage in PD, based on recruitment of alternative pathways.
Ogunsua, B. O.; Laoye, J. A.
2018-05-01
In this paper, the Tsallis non-extensive q-statistics in ionospheric dynamics was investigated using the total electron content (TEC) obtained from two Global Positioning System (GPS) receiver stations. This investigation was carried out considering the geomagnetically quiet and storm periods. The micro density variation of the ionospheric total electron content was extracted from the TEC data by method of detrending. The detrended total electron content, which represent the variation in the internal dynamics of the system was further analyzed using for non-extensive statistical mechanics using the q-Gaussian methods. Our results reveals that for all the analyzed data sets the Tsallis Gaussian probability distribution (q-Gaussian) with value q > 1 were obtained. It was observed that there is no distinct difference in pattern between the values of qquiet and qstorm. However the values of q varies with geophysical conditions and possibly with local dynamics for the two stations. Also observed are the asymmetric pattern of the q-Gaussian and a highly significant level of correlation for the q-index values obtained for the storm periods compared to the quiet periods between the two GPS receiver stations where the TEC was measured. The factors responsible for this variation can be mostly attributed to the varying mechanisms resulting in the self-reorganization of the system dynamics during the storm periods. The result shows the existence of long range correlation for both quiet and storm periods for the two stations.
Jain, Raka; Holtzman, Stephen G
2005-05-15
The purpose of this study was to determine if caffeine induces cross tolerance to the amphetamine-like discriminative stimulus effects of dopaminergic drugs that act through distinct mechanisms (e.g., release, uptake inhibition, direct activation of dopamine D(1)- or D(2)-family receptors). Rats were trained to discriminate 1.0 mg/kg d-amphetamine from saline in a two-choice discrete-trial procedure. Stimulus-generalization curves were generated by cumulative dosing for d-amphetamine (0.1-1.0 mg/kg), methylphenidate (0.3-5.6 mg/kg), SKF 81297 (0.3-3.0 mg/kg), and R-(-)-propylnorapomorphine (NPA; 0.001-1.78 mg/kg), as well as for caffeine (3.0-56 mg/kg); curves were re-determined after twice daily injections of caffeine (30 mg/kg) for 3.5 days. The rats generalized dose dependently to the four dopaminergic drugs, but only to a limited extent to caffeine. Twice daily injections of caffeine induced significant cross tolerance (i.e., increased ED(50)) to the amphetamine-like discriminative effects of methylphenidate and SKF 81297, attenuated non-significantly the effects of NPA, and did not alter the effects of amphetamine. Thus, caffeine produces differential cross tolerance to the amphetamine-like discriminative effects of dopaminergic drugs, a phenomenon in which the dopamine D(1) receptor appears to have an important role.
Marter, Kathrin; Grauel, M. Katharina; Lewa, Carmen; Morgenstern, Laura; Buckemüller, Christina; Heufelder, Karin; Ganz, Marion; Eisenhardt, Dorothea
2014-01-01
This study examines the role of stimulus duration in learning and memory formation of honeybees ("Apis mellifera"). In classical appetitive conditioning honeybees learn the association between an initially neutral, conditioned stimulus (CS) and the occurrence of a meaningful stimulus, the unconditioned stimulus (US). Thereby the CS…
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Yakovleva О.V.
2013-03-01
Full Text Available The purpose is to evaluate the effectiveness of stimulation of delivery in first mature age period of pregnant women mechanically in different somatotypes. Materials and Methods: 658 patients at 38-41 weeks of gestation of the first period of mature age (22-35 years have been considered. Differentiation by somatotypes has been performed by the method of HT Kaarma (1991. All patients of each somatotype have been divided into primiparous (n = 402 and multiparous (n = 256. Preparation for delivery by mechanical means: on the 1 st day it was introduced into the cervical canal for 16 hours, on the 2nd day — Foley catheter for 8-16 hours (before the birth. Results: In multiparous women the application of mechanical preparation of the birth canal has been effective regardless of somatotype. The percentage of operative delivery in mechanical induction has been lower in multiparous women and also not related to somatotype. In nulliparous women of asthenic and normosthenic type greater efficiency of mechanical induction in preparation for delivery has been revealed. In asthenic and pyknictype mechanical induction has been inefficient and therefore has not been recommended for the use. Conclusion: Application of mechanical means of stimulation of delivery in nulliparous pregnant women should be performed according to their somatotype.
Brief-stimulus presentations on multiform tandem schedules
Reed, Phil
1994-01-01
Three experiments examined the influence of a brief stimulus (a light) on the behavior of food-deprived rats whose lever pressing on tandem schedules comprising components of different schedule types resulted in food presentation. In Experiment 1, either a tandem variable-ratio variable-interval or a tandem variable-interval variable-ratio schedule was used. The variable-interval requirement in the tandem variable-ratio variable-interval schedule was yoked to the time taken to complete the va...
Neurotranscriptomics: The Effects of Neonatal Stimulus Deprivation on the Rat Pineal Transcriptome.
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Stephen W Hartley
Full Text Available The term neurotranscriptomics is used here to describe genome-wide analysis of neural control of transcriptomes. In this report, next-generation RNA sequencing was using to analyze the effects of neonatal (5-days-of-age surgical stimulus deprivation on the adult rat pineal transcriptome. In intact animals, more than 3000 coding genes were found to exhibit differential expression (adjusted-p < 0.001 on a night/day basis in the pineal gland (70% of these increased at night, 376 genes changed more than 4-fold in either direction. Of these, more than two thousand genes were not previously known to be differentially expressed on a night/day basis. The night/day changes in expression were almost completely eliminated by neonatal removal (SCGX or decentralization (DCN of the superior cervical ganglia (SCG, which innervate the pineal gland. Other than the loss of rhythmic variation, surgical stimulus deprivation had little impact on the abundance of most genes; of particular interest, expression levels of the melatonin-synthesis-related genes Tph1, Gch1, and Asmt displayed little change (less than 35% following DCN or SCGX. However, strong and consistent changes were observed in the expression of a small number of genes including the gene encoding Serpina1, a secreted protease inhibitor that might influence extracellular architecture. Many of the genes that exhibited night/day differential expression in intact animals also exhibited similar changes following in vitro treatment with norepinephrine, a superior cervical ganglia transmitter, or with an analog of cyclic AMP, a norepinephrine second messenger in this tissue. These findings are of significance in that they establish that the pineal-defining transcriptome is established prior to the neonatal period. Further, this work expands our knowledge of the biological process under neural control in this tissue and underlines the value of RNA sequencing in revealing how neurotransmission influences cell
Thoma, Patrizia; Soria Bauser, Denise; Suchan, Boris
2013-08-30
This article introduces the freely available Bochum Emotional Stimulus Set (BESST), which contains pictures of bodies and faces depicting either a neutral expression or one of the six basic emotions (happiness, sadness, fear, anger, disgust, and surprise), presented from two different perspectives (0° frontal view vs. camera averted by 45° to the left). The set comprises 565 frontal view and 564 averted view pictures of real-life bodies with masked facial expressions and 560 frontal and 560 averted view faces which were synthetically created using the FaceGen 3.5 Modeller. All stimuli were validated in terms of categorization accuracy and the perceived naturalness of the expression. Additionally, each facial stimulus was morphed into three age versions (20/40/60 years). The results show high recognition of the intended facial expressions, even under speeded forced-choice conditions, as corresponds to common experimental settings. The average naturalness ratings for the stimuli range between medium and high. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.
Teaching Brain-Behavior Relations Economically with Stimulus Equivalence Technology
Fienup, Daniel M.; Covey, Daniel P.; Critchfield, Thomas S.
2010-01-01
Instructional interventions based on stimulus equivalence provide learners with the opportunity to acquire skills that are not directly taught, thereby improving the efficiency of instructional efforts. The present report describes a study in which equivalence-based instruction was used to teach college students facts regarding brain anatomy and…
Fathiazar, Elham; Anemuller, Jorn; Kretzberg, Jutta
2016-08-01
Voltage-Sensitive Dye (VSD) imaging is an optical imaging method that allows measuring the graded voltage changes of multiple neurons simultaneously. In neuroscience, this method is used to reveal networks of neurons involved in certain tasks. However, the recorded relative dye fluorescence changes are usually low and signals are superimposed by noise and artifacts. Therefore, establishing a reliable method to identify which cells are activated by specific stimulus conditions is the first step to identify functional networks. In this paper, we present a statistical method to identify stimulus-activated network nodes as cells, whose activities during sensory network stimulation differ significantly from the un-stimulated control condition. This method is demonstrated based on voltage-sensitive dye recordings from up to 100 neurons in a ganglion of the medicinal leech responding to tactile skin stimulation. Without relying on any prior physiological knowledge, the network nodes identified by our statistical analysis were found to match well with published cell types involved in tactile stimulus processing and to be consistent across stimulus conditions and preparations.
A new type of sandwich panel with periodic cellular metal cores and its mechanical performances
International Nuclear Information System (INIS)
Lim, Chae-Hong; Jeon, Insu; Kang, Ki-Ju
2009-01-01
Many studies have been performed on the mechanical properties and optimization of truss PCMs (periodic cellular metals), but those on the fabrication process, which is one of key factors determining the survivability of PCMs in the market, have been relatively limited. This study introduces a new idea on the fabrication of quasi Kagome truss cored sandwich panels, which is based on the expanded-metal process. And the mechanical behavior of the sandwich panels is to be evaluated. The mechanical strengths and failure mechanisms under compression and bending load are estimated based on elementary mechanics of materials, and the optimal design is derived. Its validity is proved by comparison with the results of experiments. The results showed that the new idea is promising with respect to all three requirements, i.e., the morphology, fabrication cost, and raw materials. The simple mechanical analysis was sufficiently effective and accurate for estimating the performance and failure mode of the sandwich panels. In the experiments, sandwich panel specimens of three different designs were compared in their bending behaviors to demonstrate sensitivity of geometric parameters. Namely, although all the designs had little difference in their load capacity-per-weight, the failure mechanisms and the behaviors after a peak load were totally different.
Existence and asymptotic estimates of periodic solutions of El Niño mechanism of atmospheric physics
International Nuclear Information System (INIS)
Xiao-Jing, Li
2010-01-01
This paper is devoted to studying the El Niño mechanism of atmospheric physics. The existence and asymptotic estimates of periodic solutions for its model are obtained by employing the technique of upper and lower solution, and using the continuation theorem of coincidence degree theory. (general)
Synaptic heterogeneity and stimulus-induced modulation of depression in central synapses.
Hunter, J D; Milton, J G
2001-08-01
Short-term plasticity is a pervasive feature of synapses. Synapses exhibit many forms of plasticity operating over a range of time scales. We develop an optimization method that allows rapid characterization of synapses with multiple time scales of facilitation and depression. Investigation of paired neurons that are postsynaptic to the same identified interneuron in the buccal ganglion of Aplysia reveals that the responses of the two neurons differ in the magnitude of synaptic depression. Also, for single neurons, prolonged stimulation of the presynaptic neuron causes stimulus-induced increases in the early phase of synaptic depression. These observations can be described by a model that incorporates two availability factors, e.g., depletable vesicle pools or desensitizing receptor populations, with different time courses of recovery, and a single facilitation component. This model accurately predicts the responses to novel stimuli. The source of synaptic heterogeneity is identified with variations in the relative sizes of the two availability factors, and the stimulus-induced decrement in the early synaptic response is explained by a slowing of the recovery rate of one of the availability factors. The synaptic heterogeneity and stimulus-induced modifications in synaptic depression observed here emphasize that synaptic efficacy depends on both the individual properties of synapses and their past history.
Nakajima, S
2000-03-14
Pigeons were trained with the A+, AB-, ABC+, AD- and ADE+ task where each of stimulus A and stimulus compounds ABC and ADE signalled food (positive trials), and each of stimulus compounds AB and AD signalled no food (negative trials). Stimuli A, B, C and E were small visual figures localised on a response key, and stimulus D was a white noise. Stimulus B was more effective than D as an inhibitor of responding to A during the training. After the birds learned to respond exclusively on the positive trials, effects of B and D on responding to C and E, respectively, were tested by comparing C, BC, E and DE trials. Stimulus B continuously facilitated responding to C on the BC test trials, but D's facilitative effect was observed only on the first DE test trial. Stimulus B also facilitated responding to E on BE test trials. Implications for the Rescorla-Wagner elemental model and the Pearce configural model of Pavlovian conditioning were discussed.
Kaufmann, Tobias; Kübler, Andrea
2014-10-01
Objective. The speed of brain-computer interfaces (BCI), based on event-related potentials (ERP), is inherently limited by the commonly used one-stimulus paradigm. In this paper, we introduce a novel paradigm that can increase the spelling speed by a factor of 2, thereby extending the one-stimulus paradigm to a two-stimulus paradigm. Two different stimuli (a face and a symbol) are presented at the same time, superimposed on different characters and ERPs are classified using a multi-class classifier. Here, we present the proof-of-principle that is achieved with healthy participants. Approach. Eight participants were confronted with the novel two-stimulus paradigm and, for comparison, with two one-stimulus paradigms that used either one of the stimuli. Classification accuracies (percentage of correctly predicted letters) and elicited ERPs from the three paradigms were compared in a comprehensive offline analysis. Main results. The accuracies slightly decreased with the novel system compared to the established one-stimulus face paradigm. However, the use of two stimuli allowed for spelling at twice the maximum speed of the one-stimulus paradigms, and participants still achieved an average accuracy of 81.25%. This study introduced an alternative way of increasing the spelling speed in ERP-BCIs and illustrated that ERP-BCIs may not yet have reached their speed limit. Future research is needed in order to improve the reliability of the novel approach, as some participants displayed reduced accuracies. Furthermore, a comparison to the most recent BCI systems with individually adjusted, rapid stimulus timing is needed to draw conclusions about the practical relevance of the proposed paradigm. Significance. We introduced a novel two-stimulus paradigm that might be of high value for users who have reached the speed limit with the current one-stimulus ERP-BCI systems.
The Effects of Stimulus Presentation Rate on the Short-Term Memory of Learning Disabled Children.
Tarver, Sara G.; Ellsworth, Patricia S.
To test the hypothesis that the developmental lag in verbal rehearsal which has been documented for the learning disabled is due to a naming speed deficit (i.e., slow retrieval of stimulus names), the serial recall performance of 64 learning disabled children at four grade levels (1, 3, 5, and 7) was compared under three stimulus presentation…
Auditory proactive interference in monkeys: the roles of stimulus set size and intertrial interval.
Bigelow, James; Poremba, Amy
2013-09-01
We conducted two experiments to examine the influences of stimulus set size (the number of stimuli that are used throughout the session) and intertrial interval (ITI, the elapsed time between trials) in auditory short-term memory in monkeys. We used an auditory delayed matching-to-sample task wherein the animals had to indicate whether two sounds separated by a 5-s retention interval were the same (match trials) or different (nonmatch trials). In Experiment 1, we randomly assigned stimulus set sizes of 2, 4, 8, 16, 32, 64, or 192 (trial-unique) for each session of 128 trials. Consistent with previous visual studies, overall accuracy was consistently lower when smaller stimulus set sizes were used. Further analyses revealed that these effects were primarily caused by an increase in incorrect "same" responses on nonmatch trials. In Experiment 2, we held the stimulus set size constant at four for each session and alternately set the ITI at 5, 10, or 20 s. Overall accuracy improved when the ITI was increased from 5 to 10 s, but it was the same across the 10- and 20-s conditions. As in Experiment 1, the overall decrease in accuracy during the 5-s condition was caused by a greater number of false "match" responses on nonmatch trials. Taken together, Experiments 1 and 2 showed that auditory short-term memory in monkeys is highly susceptible to proactive interference caused by stimulus repetition. Additional analyses of the data from Experiment 1 suggested that monkeys may make same-different judgments on the basis of a familiarity criterion that is adjusted by error-related feedback.
Defever, Emmy; Reynvoet, Bert; Gebuis, Titia
2013-10-01
Researchers investigating numerosity processing manipulate the visual stimulus properties (e.g., surface). This is done to control for the confound between numerosity and its visual properties and should allow the examination of pure number processes. Nevertheless, several studies have shown that, despite different visual controls, visual cues remained to exert their influence on numerosity judgments. This study, therefore, investigated whether the impact of the visual stimulus manipulations on numerosity judgments is dependent on the task at hand (comparison task vs. same-different task) and whether this impact changes throughout development. In addition, we examined whether the influence of visual stimulus manipulations on numerosity judgments plays a role in the relation between performance on numerosity tasks and mathematics achievement. Our findings confirmed that the visual stimulus manipulations affect numerosity judgments; more important, we found that these influences changed with increasing age and differed between the comparison and the same-different tasks. Consequently, direct comparisons between numerosity studies using different tasks and age groups are difficult. No meaningful relationship between the performance on the comparison and same-different tasks and mathematics achievement was found in typically developing children, nor did we find consistent differences between children with and without mathematical learning disability (MLD). Copyright © 2013 Elsevier Inc. All rights reserved.
Rodríguez, Gabriel; Márquez, Raúl; Gil, Marta; Alonso, Gumersinda; Hall, Geoffrey
2014-10-01
According to a recent theory (Hall & Rodriguez, 2010), the latent inhibition produced by nonreinforced exposure to a target stimulus (B) will be deepened by subsequent exposure of that stimulus in compound with another (AB). This effect of compound exposure is taken to depend on the addition of a novel A to the familiar B and is not predicted for equivalent preexposure on which AB trials precede the A trials. This prediction was tested in 2 experiments using rats. Experiment 1 used an aversive procedure with flavors as the stimuli; Experiment 2 used an appetitive procedure with visual and auditory stimuli. In both, we found that conditioning with B as the conditioned stimulus proceeded more slowly (i.e., latent inhibition was greater) in subjects given the B-AB sequence in preexposure than in subjects given the AB-B sequence.
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Jongen Ellen MM
2008-09-01
Full Text Available Abstract Background Several studies have shown that Stroop interference is stronger in children than in adults. However, in a standard Stroop paradigm, stimulus interference and response interference are confounded. The purpose of the present study was to determine whether interference at the stimulus level and the response level are subject to distinct maturational patterns across childhood. Three groups of children (6–7 year-olds, 8–9 year-olds, and 10–12 year-olds and a group of adults performed a manual Color-Object Stroop designed to disentangle stimulus interference and response interference. This was accomplished by comparing three trial types. In congruent (C trials there was no interference. In stimulus incongruent (SI trials there was only stimulus interference. In response incongruent (RI trials there was stimulus interference and response interference. Stimulus interference and response interference were measured by a comparison of SI with C, and RI with SI trials, respectively. Event-related potentials (ERPs were measured to study the temporal dynamics of these processes of interference. Results There was no behavioral evidence for stimulus interference in any of the groups, but in 6–7 year-old children ERPs in the SI condition in comparison with the C condition showed an occipital P1-reduction (80–140 ms and a widely distributed amplitude enhancement of a negative component followed by an amplitude reduction of a positive component (400–560 ms. For response interference, all groups showed a comparable reaction time (RT delay, but children made more errors than adults. ERPs in the RI condition in comparison with the SI condition showed an amplitude reduction of a positive component over lateral parietal (-occipital sites in 10–12 year-olds and adults (300–540 ms, and a widely distributed amplitude enhancement of a positive component in all age groups (680–960 ms. The size of the enhancement correlated positively
Electric stimulus duration alters network-mediated responses depending on retinal ganglion cell type
Im, Maesoon; Werginz, Paul; Fried, Shelley I.
2018-06-01
Objective. To improve the quality of artificial vision that arises from retinal prostheses, it is important to bring electrically-elicited neural activity more in line with the physiological signaling patterns that arise normally in the healthy retina. Our previous study reported that indirect activation produces a closer match to physiological responses in ON retinal ganglion cells (RGCs) than in OFF cells (Im and Fried 2015 J. Physiol. 593 3677-96). This suggests that a preferential activation of ON RGCs would shape the overall retinal response closer to natural signaling. Recently, we found that changes to the rate at which stimulation was delivered could bias responses towards a stronger ON component (Im and Fried 2016a J. Neural Eng. 13 025002), raising the possibility that changes to other stimulus parameters can similarly bias towards stronger ON responses. Here, we explore the effects of changing stimulus duration on the responses in ON and OFF types of brisk transient (BT) and brisk sustained (BS) RGCs. Approach. We used cell-attached patch clamp to record RGC spiking in the isolated rabbit retina. Targeted RGCs were first classified as ON or OFF type by their light responses, and further sub-classified as BT or BS types by their responses to both light and electric stimuli. Spiking in targeted RGCs was recorded in response to electric pulses with durations varying from 5 to100 ms. Stimulus amplitude was adjusted at each duration to hold total charge constant for all experiments. Main results. We found that varying stimulus durations modulated responses differentially for ON versus OFF cells: in ON cells, spike counts decreased significantly with increasing stimulus duration while in OFF cells the changes were more modest. The maximum ratio of ON versus OFF responses occurred at a duration of ~10 ms. The difference in response strength for BT versus BS cells was much larger in ON cells than in OFF cells. Significance. The stimulation rates preferred by
Critical period of memory enhancement during taste avoidance conditioning in Lymnaea stagnalis.
Takahashi, Tomoyo; Takigami, Satoshi; Sunada, Hiroshi; Lukowiak, Ken; Sakakibara, Manabu
2013-01-01
The present study investigated the optimal training procedure leading to long-lasting taste avoidance behavior in Lymnaea. A training procedure comprising 5 repeated pairings of a conditional stimulus (CS, sucrose), with an unconditional stimulus (US, a tactile stimulation to the animal's head), over a 4-day period resulted in an enhanced memory formation than 10 CS-US repeated pairings over a 2-day period or 20 CS-US repeated pairings on a single day. Backward conditioning (US-CS) pairings did not result in conditioning. Thus, this taste avoidance conditioning was CS-US pairing specific. Food avoidance behavior was not observed following training, however, if snails were immediately subjected to a cold-block (4°C for 10 min). It was critical that the cold-block be applied within 10 min to block long-term memory (LTM) formation. Further, exposure to the cold-block 180 min after training also blocked both STM and LTM formation. The effects of the cold-block on subsequent learning and memory formation were also examined. We found no long lasting effects of the cold-block on subsequent memory formation. If protein kinase C was activated before the conditioning paradigm, snails could still acquire STM despite exposure to the cold-block.
Critical period of memory enhancement during taste avoidance conditioning in Lymnaea stagnalis.
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Tomoyo Takahashi
Full Text Available The present study investigated the optimal training procedure leading to long-lasting taste avoidance behavior in Lymnaea. A training procedure comprising 5 repeated pairings of a conditional stimulus (CS, sucrose, with an unconditional stimulus (US, a tactile stimulation to the animal's head, over a 4-day period resulted in an enhanced memory formation than 10 CS-US repeated pairings over a 2-day period or 20 CS-US repeated pairings on a single day. Backward conditioning (US-CS pairings did not result in conditioning. Thus, this taste avoidance conditioning was CS-US pairing specific. Food avoidance behavior was not observed following training, however, if snails were immediately subjected to a cold-block (4°C for 10 min. It was critical that the cold-block be applied within 10 min to block long-term memory (LTM formation. Further, exposure to the cold-block 180 min after training also blocked both STM and LTM formation. The effects of the cold-block on subsequent learning and memory formation were also examined. We found no long lasting effects of the cold-block on subsequent memory formation. If protein kinase C was activated before the conditioning paradigm, snails could still acquire STM despite exposure to the cold-block.
Investigation of the speed of reaction on external stimulus in schizophrenic psychosis.
Zampera, E
1997-06-01
In 30 schizophrenic examinees, the latention time was measured. This time is referred to as an interval between the start of the stimulus and the response to the stimulus in the skin-galvanic reflex. Elementary stimulation has been applied, using device's timer tone and clapping of hands, which should simulate and associate the thunderclap. The intensity of psychosis was measured according to the Metric scale of psychotic behavior by Rogina, while the intensity of anxiety was measured by psychological tests: Rorschach's psycho-diagnostic test and Spillberger's questionnaire for anxiety. The reaction to the stimulus and latention time were registered using polygraph unit in order to record skin-galvanic reflex. The research was performed at two separate time points: prior to the therapy with derivatives of the phenothiazine group (the experimental examination group), and 25 days after the therapy (control group). The research has shown that the latention time in schizophrenic examinees does not significantly differ from the corresponding time in healthy controls, and it averages 2.30 seconds. Furthermore, no statistically significant difference in latention time before and after the therapy was observed. However, before the therapy started, i.e. in experimental group," the examinees who were psychotic to a greater extent have shown longer latention than those less psychotic. Additional finding was that the examinees from experimental group who were more anxious according to psychological tests have also shown longer latention time. After the therapy, the reaction to the external stimulus was stronger, which was expressed in increased reaction amplitude in skin-galvanic reflex. The latention time was prolonged, especially in case of examinees that were psychotic to a smaller extent before the therapy. We can conclude that so-called transformed psychotic anxiety was replaced after the therapy with a "new" anxiety-existential fear, i.e. the stronger anxious expectation
Near-field visual acuity of pigeons: effects of head location and stimulus luminance.
Hodos, W; Leibowitz, R W; Bonbright, J C
1976-03-01
Two pigeons were trained to discriminate a grating stimulus from a blank stimulus of equivalent luminance in a three-key chamber. The stimuli and blanks were presented behind a transparent center key. The procedure was a conditional discrimination in which pecks on the left key were reinforced if the blank had been present behind the center key and pecks on the right key were reinforced if the grating had been present behind the center key. The spatial frequency of the stimuli was varied in each session from four to 29.5 lines per millimeter in accordance with a variation of the method of constant stimuli. The number of lines per millimeter that the subjects could discriminate at threshold was determined from psychometric functions. Data were collected at five values of stimulus luminance ranging from--0.07 to 3.29 log cd/m2. The distance from the stimulus to the anterior nodal point of the eye, which was determined from measurements taken from high-speed motion-picture photographs of three additional pigeons and published intraocular measurements, was 62.0 mm. This distance and the grating detection thresholds were used to calculate the visual acuity of the birds at each level of luminance. Acuity improved with increasing luminance to a peak value of 0.52, which corresponds to a visual angle of 1.92 min, at a luminance of 2.33 log cd/m2. Further increase in luminance produced a small decline in acuity.
Characteristics and formation mechanism for stainless steel fiber with periodic micro-fins
Tang, Tao; Wan, Zhenping; Lu, Longsheng; Tang, Yong
2016-05-01
Metal fibers have been widely used in many industrial applications due to their unique advantages. In certain applications, such as catalyst supports or orthopedic implants, a rough surface or tiny outshoots on the surface of metal fibers to increase surface area are needed. However, it has not been concerned about the surface morphologies of metal fiber in the current research of metal fiber manufacturing. In this paper, a special multi-tooth tool composed of a row of triangular tiny teeth is designed. The entire cutting layer of multi-tooth tool bifurcates into several thin cutting layers due to tiny teeth involved in cutting. As a result, several stainless steel fibers with periodic micro-fins are produced simultaneously. Morphology of periodic micro-fins is found to be diverse and can be classified into three categories: unilateral plane, unilateral tapering and bilateral. There are two forming mechanisms for the micro-fins. One is that periodic burrs remained on the free side of cutting layer of a tiny tooth create micro-fins of stainless steel fiber produced by the next neighboring tiny tooth; the other is that the connections between two fibers stuck together come to be micro-fins if the two fibers are finally detached. Influence of cutting conditions on formation of micro-fins is investigated. Experimental results show that cutting depth has no significant effect on micro-fin formation, high cutting speed is conducive to micro-fin formation, and feed should be between 0.12 mm/r and 0.2 mm/r to reliably obtain stainless steel fiber with micro-fins. This research presents a new pattern of stainless steel fiber characterized by periodic micro-fins formed on the edge of fiber and its manufacturing method.
Gamma oscillation maintains stimulus structure-dependent synchronization in cat visual cortex.
Samonds, Jason M; Bonds, A B
2005-01-01
Visual cortical cells demonstrate both oscillation and synchronization, although the underlying causes and functional significance of these behaviors remain uncertain. We simultaneously recorded single-unit activity with microelectrode arrays in supragranular layers of area 17 of cats paralyzed and anesthetized with propofol and N(2)O. Rate-normalized autocorrelograms of 24 cells reveal bursting (100%) and gamma oscillation (63%). Renewal density analysis, used to explore the source of oscillation, suggests a contribution from extrinsic influences such as feedback. However, a bursting refractory period, presumably membrane-based, could also encourage oscillatory firing. When we investigated the source of synchronization for 60 cell pairs we found only moderate correlation of synchrony with bursts and oscillation. We did, nonetheless, discover a possible functional role for oscillation. In all cases of cross-correlograms that exhibited oscillation, the strength of the synchrony was maintained throughout the stimulation period. When no oscillation was apparent, 75% of the cell pairs showed decay in their synchronization. The synchrony between cells is strongly dependent on similar response onset latencies. We therefore propose that structured input, which yields tight organization of latency, is a more likely candidate for the source of synchronization than oscillation. The reliable synchrony at response onset could be driven by spatial and temporal correlation of the stimulus that is preserved through the earlier stages of the visual system. Oscillation then contributes to maintenance of the synchrony to enhance reliable transmission of the information for higher cognitive processing.
Towards Predicting Room Acoustical Effects on Sound-Field ASSR from Stimulus Modulation Power
DEFF Research Database (Denmark)
Zapata Rodriguez, Valentina; Laugesen, Søren; Jeong, Cheol-Ho
) is considered. Instead of using insert earphones to deliver the stimuli, as is customary, the auditory signals are reproduced from a loudspeaker placed in front of the subject, so as to include the hearing aid in the transmission path. Loudspeaker presentation of the stimulus can lower its effective modulation...... properties of the measurement room has not been considered. The present work explores the relation between the stimulus modulation power and the ASSR amplitude in a simulated sound-field ASSR data set with varying reverberation time. Three rooms were simulated using the Green's function approach...
Tanaka, Tomohiro; Nishida, Satoshi
2015-01-01
The neuronal processes that underlie visual searches can be divided into two stages: target discrimination and saccade preparation/generation. This predicts that the length of time of the prediscrimination stage varies according to the search difficulty across different stimulus conditions, whereas the length of the latter postdiscrimination stage is stimulus invariant. However, recent studies have suggested that the length of the postdiscrimination interval changes with different stimulus conditions. To address whether and how the visual stimulus affects determination of the postdiscrimination interval, we recorded single-neuron activity in the lateral intraparietal area (LIP) when monkeys (Macaca fuscata) performed a color-singleton search involving four stimulus conditions that differed regarding luminance (Bright vs. Dim) and target-distractor color similarity (Easy vs. Difficult). We specifically focused on comparing activities between the Bright-Difficult and Dim-Easy conditions, in which the visual stimuli were considerably different, but the mean reaction times were indistinguishable. This allowed us to examine the neuronal activity when the difference in the degree of search speed between different stimulus conditions was minimal. We found that not only prediscrimination but also postdiscrimination intervals varied across stimulus conditions: the postdiscrimination interval was longer in the Dim-Easy condition than in the Bright-Difficult condition. Further analysis revealed that the postdiscrimination interval might vary with stimulus luminance. A computer simulation using an accumulation-to-threshold model suggested that the luminance-related difference in visual response strength at discrimination time could be the cause of different postdiscrimination intervals. PMID:25995344
Kishore, Pabbisetti Vayu Nandana; Madhuvarasu, Sai Shankar; Moru, Satyanarayana
2018-01-01
This paper proposes a chemo-mechanical-optical sensing approach for the detection of carcinogenic chromium (VI) metal ion using an etched fiber Bragg grating (FBG) coated with stimulus responsive hydrogel. Hydrogel synthesized from the blends of (3-acrylamidopropyl)-trimethylammonium chloride, which is highly responsive to chromium ions suffers a volume change when placed in Cr solution. When the proposed sensor system is exposed to various concentrations of Cr (VI) ion solution, FBG peak shifts due to the mechanical strain induced by the swelling of the hydrogel. The peak shift is correlated with the concentration of the Cr (VI) metal ion. Due to the reduction in the cladding diameter of FBG, wastage of swelling force due to hydrogel on FBG is lowered and utilized for more wavelength peak shift of FBG resulting in the increase in the sensitivity. The resolution of the sensor system is found to be 0.072 ppb. Trace amounts of chromium (VI) ion as low as 10 ppb can be sensed by this method. The sensor has shown good sensitivity, selectivity, and repeatability. The salient features of the sensors are its compact size, light weight, and adoptability for remote monitoring.
Comparative Evaluation of Tactile Sensation by Electrical and Mechanical Stimulation.
Yem, Vibol; Kajimoto, Hiroyuki
2017-01-01
An electrotactile display is a tactile interface that provides tactile perception by passing electrical current through the surface of the skin. It is actively used instead of mechanical tactile displays for tactile feedback because of several advantages such as its small and thin size, light weight, and high responsiveness. However, the similarities and differences between these sensations is still not clear. This study directly compares the intensity sensation of electrotactile stimulation to that of mechanical stimulation, and investigates the characteristic sensation of anodic and cathodic stimulation. In the experiment, participants underwent a 30 pps electrotactile stimulus every one second to their middle finger, and were asked to match this intensity by adjusting the intensity of a mechanical tactile stimulus to an index finger. The results showed that anodic stimulation mainly produced vibration sensation, whereas cathodic sensation produced both vibration and pressure sensations. Relatively low pressure sensation was also observed for anodic stimulation but it remains low, regardless of the increasing of electrical intensity.
Directory of Open Access Journals (Sweden)
Erik S. te Woerd
2015-01-01
Full Text Available The basal ganglia play an important role in beat perception and patients with Parkinson’s disease (PD are impaired in perception of beat-based rhythms. Rhythmic cues are nonetheless beneficial in gait rehabilitation, raising the question how rhythm improves movement in PD. We addressed this question with magnetoencephalography recordings during a choice response task with rhythmic and non-rhythmic modes of stimulus presentation. Analyses focused on (i entrainment of slow oscillations, (ii the depth of beta power modulation, and (iii whether a gain in modulation depth of beta power, due to rhythmicity, is of predictive or reactive nature. The results show weaker phase synchronisation of slow oscillations and a relative shift from predictive to reactive movement-related beta suppression in PD. Nonetheless, rhythmic stimulus presentation increased beta modulation depth to the same extent in patients and controls. Critically, this gain selectively increased the predictive and not reactive movement-related beta power suppression. Operation of a predictive mechanism, induced by rhythmic stimulation, was corroborated by a sensory gating effect in the sensorimotor cortex. The predictive mode of cue utilisation points to facilitation of basal ganglia-premotor interactions, contrasting with the popular view that rhythmic stimulation confers a special advantage in PD, based on recruitment of alternative pathways.
Spatiotemporal dynamics of cortical representations during and after stimulus presentation
Nieuwenhuijzen, M.E. van de; Borne, E.W.P. van den; Jensen, O.; Gerven, M.A.J. van
2016-01-01
Visual perception is a spatiotemporally complex process. In this study, we investigated cortical dynamics during and after stimulus presentation. We observed that visual category information related to the difference between faces and objects became apparent in the occipital lobe after 63 ms. Within
Kozyrev, S A; Nikitin, V P
2013-03-01
We studied the involvement of translation and transcription processes into behavioral and neuronal mechanisms of reconsolidation of the long-term memory of the conditioned taste aversion in edible snails. Injection of cycloheximide (an inhibitor of protein synthesis) to the snails in 48 h after training combined with subsequent reminder and presentation of the conditional stimulus resulted in the development of persistent amnesia and depression of the responses of the defensive behavior command neurons LPl1 and RPl1 to the conditional stimulus. Injection of mRNA synthesis inhibitors actinomycin D or DRB (5,6-dichloro-1-β-D-ribofuranosylbenzimidasole) in 48 h after conditioning with subsequent reminding procedure produced no effects on memory retention and on the responses of the command neurons to the conditional stimulus. The study suggests that the proteins translated from previously synthesized and stored mRNA were involved in the mechanisms of reconsolidation of the memory responsible for conditioned taste aversion.
Mishra, Jyoti; Zanto, Theodore; Nilakantan, Aneesha; Gazzaley, Adam
2013-08-01
Intrasensory interference during visual working memory (WM) maintenance by object stimuli (such as faces and scenes), has been shown to negatively impact WM performance, with greater detrimental impacts of interference observed in aging. Here we assessed age-related impacts by intrasensory WM interference from lower-level stimulus features such as visual and auditory motion stimuli. We consistently found that interference in the form of ignored distractions and secondary task interruptions presented during a WM maintenance period, degraded memory accuracy in both the visual and auditory domain. However, in contrast to prior studies assessing WM for visual object stimuli, feature-based interference effects were not observed to be significantly greater in older adults. Analyses of neural oscillations in the alpha frequency band further revealed preserved mechanisms of interference processing in terms of post-stimulus alpha suppression, which was observed maximally for secondary task interruptions in visual and auditory modalities in both younger and older adults. These results suggest that age-related sensitivity of WM to interference may be limited to complex object stimuli, at least at low WM loads. Copyright © 2013 Elsevier Ltd. All rights reserved.
The Honolulu posttraumatic stress disorder stimulus set.
Chemtob, C M; Roitblat, H L; Hamada, R S; Carlson, J G; Muraoka, M Y; Bauer, G B
1997-04-01
We present word and picture stimuli constituting a validated stimulus set appropriate for cognitive investigations of posttraumatic stress disorder (PTSD). Combat related and neutral words and pictures were rated by Vietnam veterans with PTSD and by three comparison groups along four dimensions: unpleasantness, Vietnam relevance, stressfulness, and memorability. There were distinctive patterns of responses by the PTSD group which efficiently discriminated the individuals in this group from those in the control groups. These stimuli have the potential to be developed as a diagnostic instrument.
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Vincent Anne
2005-03-01
Full Text Available Abstract Background In mammals, the CNS vasculature is established during the postnatal period via active angiogenesis, providing different brain regions with capillary networks of various densities that locally supply adapted metabolic support to neurons. Thereafter this vasculature remains essentially quiescent excepted for specific pathologies. In the adult rat hypothalamus, a particularly dense network of capillary vessels is associated with the supraoptic (SON and paraventricular (PVN nuclei containing the magnocellular neurons secreting vasopressin and oxytocin, two neurohormones involved in the control of the body fluid homoeostasis. In the seventies, it was reported that proliferation of astrocytes and endothelial cells occurs within these hypothalamic nuclei when strong metabolic activation of the vasopressinergic and oxytocinergic neurons was induced by prolonged hyperosmotic stimulation. The aim of the present study was to determine whether such proliferative response to osmotic stimulus is related to local angiogenesis and to elucidate the cellular and molecular mechanisms involved. Results Our results provide evidence that cell proliferation occurring within the SON of osmotically stimulated adult rats corresponds to local angiogenesis. We show that 1 a large majority of the SON proliferative cells is associated with capillary vessels, 2 this proliferative response correlates with a progressive increase in density of the capillary network within the nucleus, and 3 SON capillary vessels exhibit an increased expression of nestin and vimentin, two markers of newly formed vessels. Contrasting with most adult CNS neurons, hypothalamic magnocellular neurons were found to express vascular endothelial growth factor (VEGF, a potent angiogenic factor whose production was increased by osmotic stimulus. When VEGF was inhibited by dexamethasone treatment or by the local application of a blocking antibody, the angiogenic response was strongly
Canadell, Marta; Haro, Àlex
2017-12-01
We present several algorithms for computing normally hyperbolic invariant tori carrying quasi-periodic motion of a fixed frequency in families of dynamical systems. The algorithms are based on a KAM scheme presented in Canadell and Haro (J Nonlinear Sci, 2016. doi: 10.1007/s00332-017-9389-y), to find the parameterization of the torus with prescribed dynamics by detuning parameters of the model. The algorithms use different hyperbolicity and reducibility properties and, in particular, compute also the invariant bundles and Floquet transformations. We implement these methods in several 2-parameter families of dynamical systems, to compute quasi-periodic arcs, that is, the parameters for which 1D normally hyperbolic invariant tori with a given fixed frequency do exist. The implementation lets us to perform the continuations up to the tip of the quasi-periodic arcs, for which the invariant curves break down. Three different mechanisms of breakdown are analyzed, using several observables, leading to several conjectures.
Celletti, A
2006-01-01
The book provides the most recent advances of Celestial Mechanics, as provided by high-level scientists working in this field. It covers theoretical investigations as well as applications to concrete problems. Outstanding review papers are included in the book and they introduce the reader to leading subjects, like the variational approaches to find periodic orbits, the stability theory of the N-body problem, the spin-orbit resonances and chaotic dynamics, the space debris polluting the circumterrestrial space.
Sergent, Claire; Ruff, Christian C; Barbot, Antoine; Driver, Jon; Rees, Geraint
2011-08-01
Modulations of sensory processing in early visual areas are thought to play an important role in conscious perception. To date, most empirical studies focused on effects occurring before or during visual presentation. By contrast, several emerging theories postulate that sensory processing and conscious visual perception may also crucially depend on late top-down influences, potentially arising after a visual display. To provide a direct test of this, we performed an fMRI study using a postcued report procedure. The ability to report a target at a specific spatial location in a visual display can be enhanced behaviorally by symbolic auditory postcues presented shortly after that display. Here we showed that such auditory postcues can enhance target-specific signals in early human visual cortex (V1 and V2). For postcues presented 200 msec after stimulus termination, this target-specific enhancement in visual cortex was specifically associated with correct conscious report. The strength of this modulation predicted individual levels of performance in behavior. By contrast, although later postcues presented 1000 msec after stimulus termination had some impact on activity in early visual cortex, this modulation no longer related to conscious report. These results demonstrate that within a critical time window of a few hundred milliseconds after a visual stimulus has disappeared, successful conscious report of that stimulus still relates to the strength of top-down modulation in early visual cortex. We suggest that, within this critical time window, sensory representation of a visual stimulus is still under construction and so can still be flexibly influenced by top-down modulatory processes.
The local enhancement conundrum: in search of the adaptive value of a social learning mechanism.
Arbilly, Michal; Laland, Kevin N
2014-02-01
Social learning mechanisms are widely thought to vary in their degree of complexity as well as in their prevalence in the natural world. While learning the properties of a stimulus that generalize to similar stimuli at other locations (stimulus enhancement) prima facie appears more useful to an animal than learning about a specific stimulus at a specific location (local enhancement), empirical evidence suggests that the latter is much more widespread in nature. Simulating populations engaged in a producer-scrounger game, we sought to deploy mathematical models to identify the adaptive benefits of reliance on local enhancement and/or stimulus enhancement, and the alternative conditions favoring their evolution. Surprisingly, we found that while stimulus enhancement readily evolves, local enhancement is advantageous only under highly restricted conditions: when generalization of information was made unreliable or when error in social learning was high. Our results generate a conundrum over how seemingly conflicting empirical and theoretical findings can be reconciled. Perhaps the prevalence of local enhancement in nature is due to stimulus enhancement costs independent of the learning task itself (e.g. predation risk), perhaps natural habitats are often characterized by unreliable yet highly rewarding payoffs, or perhaps local enhancement occurs less frequently, and stimulus enhancement more frequently, than widely believed. Copyright © 2013 Elsevier Inc. All rights reserved.
Did Fiscal Stimulus Lift Developing Asia Out of the Global Crisis? An Empirical Investigation
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Seok-Kyun Hur
2018-03-01
Full Text Available The substantial slowdown of economic growth since the global financial crisis of 2008-2009 is rekindling debate on whether developing Asia should use fiscal expansion to boost aggregate demand. A key factor in the debate is the effectiveness of countercyclical fiscal policy in the region. The global crisis, as well as the fiscal stimulus packages implemented by developing Asian countries at that time, give some clues to this important issue. The region weathered the global crisis well and experienced a robust V-shaped recovery. According to conventional wisdom, the fiscal stimulus packages put in place by Asian governments played a key role in the region’s recovery. The central objective of this paper is to empirically test this wisdom by using cross-country panel data. Our main finding is that the stimulus has had a limited but positive impact on developing Asia’s output during the global crisis. This lends some support to the notion that countercyclical fiscal policy can help the region cope with severe external shocks. The broader, more fundamental implication for regional policymakers is that the region’s long-standing commitment to fiscal discipline can yield significant benefits beyond macroeconomic stability. An important consequence of this commitment - relatively healthy fiscal balance sheets - enabled the region’s governments to quickly and decisively embark upon fiscal stimulus programs.
Treccani, Barbara; Milanese, Nadia; Umilta, Carlo
2010-01-01
In 4 experiments, we intermixed trials in which the stimulus color was relevant with trials where participants had to judge the stimulus shape or parity and found that the logical-recoding rule (Hedge & Marsh, 1975) applied to the relevant dimension in a task can generalize to the irrelevant dimension of the other task. The mapping…
Bühler, Mira; Vollstädt-Klein, Sabine; Klemen, Jane; Smolka, Michael N
2008-07-22
Existing brain imaging studies, investigating sexual arousal via the presentation of erotic pictures or film excerpts, have mainly used blocked designs with long stimulus presentation times. To clarify how experimental functional magnetic resonance imaging (fMRI) design affects stimulus-induced brain activity, we compared brief event-related presentation of erotic vs. neutral stimuli with blocked presentation in 10 male volunteers. Brain activation differed depending on design type in only 10% of the voxels showing task related brain activity. Differences between blocked and event-related stimulus presentation were found in occipitotemporal and temporal regions (Brodmann Area (BA) 19, 37, 48), parietal areas (BA 7, 40) and areas in the frontal lobe (BA 6, 44). Our results suggest that event-related designs might be a potential alternative when the core interest is the detection of networks associated with immediate processing of erotic stimuli.Additionally, blocked, compared to event-related, stimulus presentation allows the emergence and detection of non-specific secondary processes, such as sustained attention, motor imagery and inhibition of sexual arousal.
Directory of Open Access Journals (Sweden)
Klemen Jane
2008-07-01
Full Text Available Abstract Background Existing brain imaging studies, investigating sexual arousal via the presentation of erotic pictures or film excerpts, have mainly used blocked designs with long stimulus presentation times. Methods To clarify how experimental functional magnetic resonance imaging (fMRI design affects stimulus-induced brain activity, we compared brief event-related presentation of erotic vs. neutral stimuli with blocked presentation in 10 male volunteers. Results Brain activation differed depending on design type in only 10% of the voxels showing task related brain activity. Differences between blocked and event-related stimulus presentation were found in occipitotemporal and temporal regions (Brodmann Area (BA 19, 37, 48, parietal areas (BA 7, 40 and areas in the frontal lobe (BA 6, 44. Conclusion Our results suggest that event-related designs might be a potential alternative when the core interest is the detection of networks associated with immediate processing of erotic stimuli. Additionally, blocked, compared to event-related, stimulus presentation allows the emergence and detection of non-specific secondary processes, such as sustained attention, motor imagery and inhibition of sexual arousal.
Kober, Silvia Erika; Witte, Matthias; Stangl, Matthias; Väljamäe, Aleksander; Neuper, Christa; Wood, Guilherme
2015-01-01
In the present study, we investigated how the electrical activity in the sensorimotor cortex contributes to improved cognitive processing capabilities and how SMR (sensorimotor rhythm, 12-15Hz) neurofeedback training modulates it. Previous evidence indicates that higher levels of SMR activity reduce sensorimotor interference and thereby promote cognitive processing. Participants were randomly assigned to two groups, one experimental (N=10) group receiving SMR neurofeedback training, in which they learned to voluntarily increase SMR, and one control group (N=10) receiving sham feedback. Multiple cognitive functions and electrophysiological correlates of cognitive processing were assessed before and after 10 neurofeedback training sessions. The experimental group but not the control group showed linear increases in SMR power over training runs, which was associated with behavioural improvements in memory and attentional performance. Additionally, increasing SMR led to a more salient stimulus processing as indicated by increased N1 and P3 event-related potential amplitudes after the training as compared to the pre-test. Finally, functional brain connectivity between motor areas and visual processing areas was reduced after SMR training indicating reduced sensorimotor interference. These results indicate that SMR neurofeedback improves stimulus processing capabilities and consequently leads to improvements in cognitive performance. The present findings contribute to a better understanding of the mechanisms underlying SMR neurofeedback training and cognitive processing and implicate that SMR neurofeedback might be an effective cognitive training tool. Copyright © 2014 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.
The transfer of social exclusion and inclusion functions through derived stimulus relations.
Munnelly, Anita; Martin, Georgina; Dack, Charlotte; Zedginidze, Ann; McHugh, Louise
2014-09-01
Previous studies have found that social exclusion can cause distress to those excluded. One method used to study social exclusion is through a virtual ball-toss game known as Cyberball. In this game, participants may be excluded from or included in the ball-toss game and typically report lower feelings of self-esteem, control, belonging, and meaningful existence following exclusion. Experiments 1 and 2 sought to explore the transfer of feelings of exclusion and inclusion through stimulus equivalence classes. In both experiments, participants were trained to form two three-member equivalence classes (e.g., A1-B1, B1-C1; A2-B2, B2-C2) and were tested with novel stimulus combinations (A1-C1, C1-A1, A2-C2, C2-A2). Thereafter, participants were exposed to the Cyberball exclusion and inclusion games. In these games, one stimulus (C1) from one equivalence class was assigned as the Cyberball inclusion game name, whereas one stimulus (C2) from the other equivalence class was assigned as the Cyberball exclusion game name. In Experiment 2, participants were only exposed to the Cyberball exclusion game. During a subsequent transfer test, participants were asked to rate how included in or excluded from they thought they would be in other online games, corresponding to members of both equivalence classes. Participant reported that they felt they would be excluded from online games if the games were members of the same equivalence class as C2. In contrast, participants reported that they felt they would be included in online games if the games were members of the same equivalence class as C1. Results indicated the transfer of feelings of inclusion (Experiment 1) and feelings of exclusion (Experiments 1 and 2) through equivalence classes.
Discriminative learning of receptive fields from responses to non-Gaussian stimulus ensembles.
Meyer, Arne F; Diepenbrock, Jan-Philipp; Happel, Max F K; Ohl, Frank W; Anemüller, Jörn
2014-01-01
Analysis of sensory neurons' processing characteristics requires simultaneous measurement of presented stimuli and concurrent spike responses. The functional transformation from high-dimensional stimulus space to the binary space of spike and non-spike responses is commonly described with linear-nonlinear models, whose linear filter component describes the neuron's receptive field. From a machine learning perspective, this corresponds to the binary classification problem of discriminating spike-eliciting from non-spike-eliciting stimulus examples. The classification-based receptive field (CbRF) estimation method proposed here adapts a linear large-margin classifier to optimally predict experimental stimulus-response data and subsequently interprets learned classifier weights as the neuron's receptive field filter. Computational learning theory provides a theoretical framework for learning from data and guarantees optimality in the sense that the risk of erroneously assigning a spike-eliciting stimulus example to the non-spike class (and vice versa) is minimized. Efficacy of the CbRF method is validated with simulations and for auditory spectro-temporal receptive field (STRF) estimation from experimental recordings in the auditory midbrain of Mongolian gerbils. Acoustic stimulation is performed with frequency-modulated tone complexes that mimic properties of natural stimuli, specifically non-Gaussian amplitude distribution and higher-order correlations. Results demonstrate that the proposed approach successfully identifies correct underlying STRFs, even in cases where second-order methods based on the spike-triggered average (STA) do not. Applied to small data samples, the method is shown to converge on smaller amounts of experimental recordings and with lower estimation variance than the generalized linear model and recent information theoretic methods. Thus, CbRF estimation may prove useful for investigation of neuronal processes in response to natural stimuli and
Discriminative learning of receptive fields from responses to non-Gaussian stimulus ensembles.
Directory of Open Access Journals (Sweden)
Arne F Meyer
Full Text Available Analysis of sensory neurons' processing characteristics requires simultaneous measurement of presented stimuli and concurrent spike responses. The functional transformation from high-dimensional stimulus space to the binary space of spike and non-spike responses is commonly described with linear-nonlinear models, whose linear filter component describes the neuron's receptive field. From a machine learning perspective, this corresponds to the binary classification problem of discriminating spike-eliciting from non-spike-eliciting stimulus examples. The classification-based receptive field (CbRF estimation method proposed here adapts a linear large-margin classifier to optimally predict experimental stimulus-response data and subsequently interprets learned classifier weights as the neuron's receptive field filter. Computational learning theory provides a theoretical framework for learning from data and guarantees optimality in the sense that the risk of erroneously assigning a spike-eliciting stimulus example to the non-spike class (and vice versa is minimized. Efficacy of the CbRF method is validated with simulations and for auditory spectro-temporal receptive field (STRF estimation from experimental recordings in the auditory midbrain of Mongolian gerbils. Acoustic stimulation is performed with frequency-modulated tone complexes that mimic properties of natural stimuli, specifically non-Gaussian amplitude distribution and higher-order correlations. Results demonstrate that the proposed approach successfully identifies correct underlying STRFs, even in cases where second-order methods based on the spike-triggered average (STA do not. Applied to small data samples, the method is shown to converge on smaller amounts of experimental recordings and with lower estimation variance than the generalized linear model and recent information theoretic methods. Thus, CbRF estimation may prove useful for investigation of neuronal processes in response to
Hennigan, Jennifer N.; Grubbs, W. Tandy
2013-01-01
The chemical elements present in the modern periodic table are arranged in terms of atomic numbers and chemical periodicity. Periodicity arises from quantum mechanical limitations on how many electrons can occupy various shells and subshells of an atom. The shell model of the atom predicts that a maximum of 2, 8, 18, and 32 electrons can occupy…
Compound stimulus extinction reduces spontaneous recovery in humans
Coelho, Cesar A.O.; Dunsmoor, Joseph E.; Phelps, Elizabeth A.
2015-01-01
Fear-related behaviors are prone to relapse following extinction. We tested in humans a compound extinction design (“deepened extinction”) shown in animal studies to reduce post-extinction fear recovery. Adult subjects underwent fear conditioning to a visual and an auditory conditioned stimulus (CSA and CSB, respectively) separately paired with an electric shock. The target CS (CSA) was extinguished alone followed by compound presentations of the extinguished CSA and nonextinguished CSB. Reco...
Visual Short-Term Memory: is Capacity Dependent on Stimulus Complexity?
DEFF Research Database (Denmark)
Sørensen, Thomas Alrik
complexity - which is dependent on the familiarity of a given stimulus - plays a more important role than the objective visual complexity of the objects stored. In several studies, we explored how familiarity influences the capacity of VSTM and our results indicate that VSTM capacity for familiar items...
Stimulus selection and tracking during urination: autoshaping directed behavior with toilet targets.
Siegel, R K
1977-01-01
A simple procedure is described for investigating stimuli selected as targets during urination in the commode. Ten normal males preferred a floating target that could be tracked to a series of stationary targets. This technique was used to bring misdirected urinations in a severely retarded male under rapid stimulus control of a floating target in the commode. The float stimulus was also evaluated with nine institionalized, moderately retarded males and results indicated rapid autoshaping of directed urination without the use of verbal instructions or conventional toilet training. The technique can be applied in training children to control misdirected urinations in institution for the retarded, in psychiatric wards with regressed populations, and in certain male school dormitories. PMID:885828
The Wada Test: contributions to standardization of the stimulus for language and memory assessment
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Mäder Maria Joana
2004-01-01
Full Text Available The Wada Test (WT is part of the presurgical evaluation for refractory epilepsy. The WT is not standardized and the protocols differ in important ways, including stimulus type of material presented for memory testing, timing of presentations and methods of assessment. The aim of this study was to contribute to establish parameters for a WT to Brazilian population investigating the performance of 100 normal subjects, without medication. Two parallel models were used based on Montreal Procedure adapted from Gail Risse's (MEG-MN,EUA protocol. The proportions of correct responses of normal subjects submitted to two parallel WT models were investigated and the two models were compared. The results showed that the two models are similar but significant differences among the stimulus type were observed. The results suggest that the stimulus type may influence the results of the WT and should be considered when constructing models and comparing different protocols.
Rehfeldt, Ruth Anne
2011-01-01
Every article on stimulus equivalence or derived stimulus relations published in the "Journal of Applied Behavior Analysis" was evaluated in terms of characteristics that are relevant to the development of applied technologies: the type of participants, settings, procedure automated vs. tabletop), stimuli, and stimulus sensory modality; types of…
Neuronal representations of stimulus associations develop in the temporal lobe during learning.
Messinger, A; Squire, L R; Zola, S M; Albright, T D
2001-10-09
Visual stimuli that are frequently seen together become associated in long-term memory, such that the sight of one stimulus readily brings to mind the thought or image of the other. It has been hypothesized that acquisition of such long-term associative memories proceeds via the strengthening of connections between neurons representing the associated stimuli, such that a neuron initially responding only to one stimulus of an associated pair eventually comes to respond to both. Consistent with this hypothesis, studies have demonstrated that individual neurons in the primate inferior temporal cortex tend to exhibit similar responses to pairs of visual stimuli that have become behaviorally associated. In the present study, we investigated the role of these areas in the formation of conditional visual associations by monitoring the responses of individual neurons during the learning of new stimulus pairs. We found that many neurons in both area TE and perirhinal cortex came to elicit more similar neuronal responses to paired stimuli as learning proceeded. Moreover, these neuronal response changes were learning-dependent and proceeded with an average time course that paralleled learning. This experience-dependent plasticity of sensory representations in the cerebral cortex may underlie the learning of associations between objects.
Stevenson, Ryan A; Fister, Juliane Krueger; Barnett, Zachary P; Nidiffer, Aaron R; Wallace, Mark T
2012-05-01
In natural environments, human sensory systems work in a coordinated and integrated manner to perceive and respond to external events. Previous research has shown that the spatial and temporal relationships of sensory signals are paramount in determining how information is integrated across sensory modalities, but in ecologically plausible settings, these factors are not independent. In the current study, we provide a novel exploration of the impact on behavioral performance for systematic manipulations of the spatial location and temporal synchrony of a visual-auditory stimulus pair. Simple auditory and visual stimuli were presented across a range of spatial locations and stimulus onset asynchronies (SOAs), and participants performed both a spatial localization and simultaneity judgment task. Response times in localizing paired visual-auditory stimuli were slower in the periphery and at larger SOAs, but most importantly, an interaction was found between the two factors, in which the effect of SOA was greater in peripheral as opposed to central locations. Simultaneity judgments also revealed a novel interaction between space and time: individuals were more likely to judge stimuli as synchronous when occurring in the periphery at large SOAs. The results of this study provide novel insights into (a) how the speed of spatial localization of an audiovisual stimulus is affected by location and temporal coincidence and the interaction between these two factors and (b) how the location of a multisensory stimulus impacts judgments concerning the temporal relationship of the paired stimuli. These findings provide strong evidence for a complex interdependency between spatial location and temporal structure in determining the ultimate behavioral and perceptual outcome associated with a paired multisensory (i.e., visual-auditory) stimulus.
Eisenach, James C; Curry, Regina; Aschenbrenner, Carol A; Coghill, Robert C; Houle, Timothy T
2017-03-01
The locus coeruleus (LC) signals salience to sensory stimuli and these responses can modulate the experience of pain stimuli. The pupil dilation response (PDR) to noxious stimuli is thought to be a surrogate for LC responses, but PDR response to Peltier-controlled noxious heat stimuli, the most commonly used method in experimental pain research, has not been described. Healthy volunteers were presented with randomly presented heat stimuli of 5 sec duration and provided pain intensity ratings to each stimulus. Pupillometry was performed and a method developed to quantify the PDR relevant to these stimuli. The stimulus response, reliability, and effect of commonly used manipulations on pain experience were explored. A method of artifact removal and adjusting for lag from stimulus initiation to PDR response was developed, resulting in a close correlation between pain intensity rating and PDR across a large range of heat stimuli. A reliable assessment of PDR within an individual was achieved with fewer presentations as heat stimulus intensity increased. The correlation between pain rating and PDR was disrupted when cognitive load is increased by manipulating expectations or presenting a second pain stimulus. The PDR began later after skin heating than electrical stimuli and this is the first examination of the PDR using standard nociceptive testing and manipulations of expectations and competing noxious stimulation. A method is described applying PDR to standard heat nociceptive testing, demonstrating stimulus response, reliability, and disruption by cognitive manipulation. Copyright © 2017 Elsevier B.V. All rights reserved.
Directory of Open Access Journals (Sweden)
Catherine M. Sweeney-Reed
2016-09-01
Full Text Available The data presented here comprise clinical, neuropsychological, and intrathalamic electrophysiological data from 7 patients with pharmacoresistant focal epilepsy and are related to the article “Pre-stimulus thalamic theta power predicts human memory formation” C.M. Sweeney-Reed, T. Zaehle, J. Voges, F.C. Schmitt, L. Buentjen, K. Kopitzki, et al. (2016 [1]. The patients participated in a memory paradigm after receiving electrodes implanted in the DMTN due to the surgical approach taken in electrode insertion for deep brain stimulation of the anterior thalamic nucleus. Epilepsy duration and pre-operative neuropsychological tests provide an indication of the profile of patients receiving intrathalamic electrode implantation and the memory capabilities in such a patient group. The electrophysiological data were recorded from the right DMTN preceding stimulus presentation during intentional memory encoding. The patients viewed a series of photographic scenes, which they judged as indoors or outdoors. The 900 ms epochs prior to stimulus presentation were labeled as preceding successful or unsuccessful subsequent memory formation according to a subsequent memory test for the items. The difference between theta power preceding successful versus unsuccessful subsequent memory formation is shown against time for each patient individually. Keywords: Memory encoding, Dorsomedial thalamic nucleus, Pre-stimulus theta
Causer, J; McRobert, A P; Williams, A M
2013-10-01
The ability to make accurate judgments and execute effective skilled movements under severe temporal constraints are fundamental to elite performance in a number of domains including sport, military combat, law enforcement, and medicine. In two experiments, we examine the effect of stimulus strength on response time and accuracy in a temporally constrained, real-world, decision-making task. Specifically, we examine the effect of low stimulus intensity (black) and high stimulus intensity (sequin) uniform designs, worn by teammates, to determine the effect of stimulus strength on the ability of soccer players to make rapid and accurate responses. In both field- and laboratory-based scenarios, professional soccer players viewed developing patterns of play and were required to make a penetrative pass to an attacking player. Significant differences in response accuracy between uniform designs were reported in laboratory- and field-based experiments. Response accuracy was significantly higher in the sequin compared with the black uniform condition. Response times only differed between uniform designs in the laboratory-based experiment. These findings extend the literature into a real-world environment and have significant implications for the design of clothing wear in a number of domains. © 2012 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.
Boddez, Y.; Vervliet, B.; Baeyens, F.; Lauwers, S.; Hermans, D.; Beckers, T.
2012-01-01
Background and Objectives In a blocking procedure, a single conditioned stimulus (CS) is paired with an unconditioned stimulus (US), such as electric shock, in the first stage. During the subsequent stage, the CS is presented together with a second CS and this compound is followed by the same US.
Promoting Response Variability and Stimulus Generalization in Martial Arts Training
Harding, Jay W.; Wacker, David P.; Berg, Wendy K.; Rick, Gary; Lee, John F.
2004-01-01
The effects of reinforcement and extinction on response variability and stimulus generalization in the punching and kicking techniques of 2 martial arts students were evaluated across drill and sparring conditions. During both conditions, the students were asked to demonstrate different techniques in response to an instructor's punching attack.…
Stimulus Characteristics Affect Humor Processing in Individuals with Asperger Syndrome
Samson, Andrea C.; Hegenloh, Michael
2010-01-01
The present paper aims to investigate whether individuals with Asperger syndrome (AS) show global humor processing deficits or whether humor comprehension and appreciation depends on stimulus characteristics. Non-verbal visual puns, semantic and Theory of Mind cartoons were rated on comprehension, funniness and the punchlines were explained. AS…
Effective Stimulus Parameters for Directed Locomotion in Madagascar Hissing Cockroach Biobot.
Directory of Open Access Journals (Sweden)
Jonathan C Erickson
Full Text Available Swarms of insects instrumented with wireless electronic backpacks have previously been proposed for potential use in search and rescue operations. Before deploying such biobot swarms, an effective long-term neural-electric stimulus interface must be established, and the locomotion response to various stimuli quantified. To this end, we studied a variety of pulse types (mono- vs. bipolar; voltage- vs. current-controlled and shapes (amplitude, frequency, duration to parameters that are most effective for evoking locomotion along a desired path in the Madagascar hissing cockroach (G. portentosa in response to antennal and cercal stimulation. We identified bipolar, 2 V, 50 Hz, 0.5 s voltage controlled pulses as being optimal for evoking forward motion and turns in the expected contraversive direction without habituation in ≈50% of test subjects, a substantial increase over ≈10% success rates previously reported. Larger amplitudes for voltage (1-4 V and current (50-150 μA pulses generally evoked larger forward walking (15.6-25.6 cm; 3.9-5.6 cm/s but smaller concomitant turning responses (149 to 80.0 deg; 62.8 to 41.2 deg/s. Thus, the radius of curvature of the initial turn-then-run locomotor response (≈10-25 cm could be controlled in a graded manner by varying the stimulus amplitude. These findings could be used to help optimize stimulus protocols for swarms of cockroach biobots navigating unknown terrain.
Primacy Performance of Normal and Retarded Children: Stimulus Familiarity or Spatial Memory?
Swanson, Lee
1978-01-01
Explores the effect of stimulus familiarity on the spatial primacy performance of normal and retarded children. Assumes that serial recall tasks reflect spatial memory rather than verbal rehearsal. (BD)
Visual training improves perceptual grouping based on basic stimulus features.
Kurylo, Daniel D; Waxman, Richard; Kidron, Rachel; Silverstein, Steven M
2017-10-01
Training on visual tasks improves performance on basic and higher order visual capacities. Such improvement has been linked to changes in connectivity among mediating neurons. We investigated whether training effects occur for perceptual grouping. It was hypothesized that repeated engagement of integration mechanisms would enhance grouping processes. Thirty-six participants underwent 15 sessions of training on a visual discrimination task that required perceptual grouping. Participants viewed 20 × 20 arrays of dots or Gabor patches and indicated whether the array appeared grouped as vertical or horizontal lines. Across trials stimuli became progressively disorganized, contingent upon successful discrimination. Four visual dimensions were examined, in which grouping was based on similarity in luminance, color, orientation, and motion. Psychophysical thresholds of grouping were assessed before and after training. Results indicate that performance in all four dimensions improved with training. Training on a control condition, which paralleled the discrimination task but without a grouping component, produced no improvement. In addition, training on only the luminance and orientation dimensions improved performance for those conditions as well as for grouping by color, on which training had not occurred. However, improvement from partial training did not generalize to motion. Results demonstrate that a training protocol emphasizing stimulus integration enhanced perceptual grouping. Results suggest that neural mechanisms mediating grouping by common luminance and/or orientation contribute to those mediating grouping by color but do not share resources for grouping by common motion. Results are consistent with theories of perceptual learning emphasizing plasticity in early visual processing regions.
Memory reactivation in healthy aging: evidence of stimulus-specific dedifferentiation.
St-Laurent, Marie; Abdi, Hervé; Bondad, Ashley; Buchsbaum, Bradley R
2014-03-19
We investigated how aging affects the neural specificity of mental replay, the act of conjuring up past experiences in one's mind. We used functional magnetic resonance imaging (fMRI) and multivariate pattern analysis to quantify the similarity between brain activity elicited by the perception and memory of complex multimodal stimuli. Young and older human adults viewed and mentally replayed short videos from long-term memory while undergoing fMRI. We identified a wide array of cortical regions involved in visual, auditory, and spatial processing that supported stimulus-specific representation at perception as well as during mental replay. Evidence of age-related dedifferentiation was subtle at perception but more salient during mental replay, and age differences at perception could not account for older adults' reduced neural reactivation specificity. Performance on a post-scan recognition task for video details correlated with neural reactivation in young but not in older adults, indicating that in-scan reactivation benefited post-scan recognition in young adults, but that some older adults may have benefited from alternative rehearsal strategies. Although young adults recalled more details about the video stimuli than older adults on a post-scan recall task, patterns of neural reactivation correlated with post-scan recall in both age groups. These results demonstrate that the mechanisms supporting recall and recollection are linked to accurate neural reactivation in both young and older adults, but that age affects how efficiently these mechanisms can support memory's representational specificity in a way that cannot simply be accounted for by degraded sensory processes.
Directory of Open Access Journals (Sweden)
Andreas Haga
2016-11-01
Full Text Available Visiting or viewing nature environments can have restorative psychological effects, while exposure to the built environment typically has less positive effects. A classic view is that this difference in restorative potential of nature and built environments depends on differences in the intrinsic characteristics of the stimuli. In addition, an evolutionary account is often assumed whereby restoration is believed to be a hardwired response to nature’s stimulus-features. Here, we propose the novel hypothesis that the restorative effects of a stimulus do not entirely depend on the stimulus-features per se, but also on the meaning that people assign to the stimulus. Participants conducted cognitively demanding tests prior to and after a brief pause. During the pause, the participants were exposed to an ambiguous sound consisting of pink noise with white noise interspersed. Participants in the nature sound-source condition were told that the sound originated from a nature scene with a waterfall; participants in the industrial sound-source condition were told that the sound originated from an industrial environment with machinery; and participants in the control condition were told nothing about the sound origin. Self-reported mental exhaustion showed that participants in the nature sound-source condition were more psychologically restored after the pause than participants in the industrial sound-source condition. One potential interpretation of the results is that restoration from nature experiences depends on learned, positive associations with nature; not only on hardwired responses shaped by evolution.
A systematic analysis of the Braitenberg vehicle 2b for point-like stimulus sources
International Nuclear Information System (INIS)
Rañó, Iñaki
2012-01-01
Braitenberg vehicles have been used experimentally for decades in robotics with limited empirical understanding. This paper presents the first mathematical model of the vehicle 2b, displaying so-called aggression behaviour, and analyses the possible trajectories for point-like smooth stimulus sources. This sensory-motor steering control mechanism is used to implement biologically grounded target approach, target-seeking or obstacle-avoidance behaviour. However, the analysis of the resulting model reveals that complex and unexpected trajectories can result even for point-like stimuli. We also prove how the implementation of the controller and the vehicle morphology interact to affect the behaviour of the vehicle. This work provides a better understanding of Braitenberg vehicle 2b, explains experimental results and paves the way for a formally grounded application on robotics as well as for a new way of understanding target seeking in biology. (paper)
DEFF Research Database (Denmark)
Dühring, Maria Bayard; Laude, Vincent; Khelif, Abdelkrim
2009-01-01
It has been shown previously that surface acoustic waves can be efficiently trapped and slowed by steep ridges on a piezoelectric substrate, giving rise to two families of shear-horizontal and vertically polarized surface waves. The mechanisms of energy storage and dispersion are explored by using...... the finite element method to model surface acoustic waves generated by high aspect ratio electrodes. A periodic model is proposed including a perfectly matched layer to simulate radiation conditions away from the sources, from which the modal distributions are found. The ratio of the mechanical energy...... confined to the electrode as compared to the total mechanical energy is calculated and is found to be increasing for increasing aspect ratio and to tend to a definite limit for the two families of surface waves. This observation is in support of the interpretation that high aspect ratio electrodes act...
Mode-locking behavior of Izhikevich neurons under periodic external forcing
Farokhniaee, AmirAli; Large, Edward W.
2017-06-01
Many neurons in the auditory system of the brain must encode periodic signals. These neurons under periodic stimulation display rich dynamical states including mode locking and chaotic responses. Periodic stimuli such as sinusoidal waves and amplitude modulated sounds can lead to various forms of n :m mode-locked states, in which a neuron fires n action potentials per m cycles of the stimulus. Here, we study mode-locking in the Izhikevich neurons, a reduced model of the Hodgkin-Huxley neurons. The Izhikevich model is much simpler in terms of the dimension of the coupled nonlinear differential equations compared with other existing models, but excellent for generating the complex spiking patterns observed in real neurons. We obtained the regions of existence of the various mode-locked states on the frequency-amplitude plane, called Arnold tongues, for the Izhikevich neurons. Arnold tongue analysis provides useful insight into the organization of mode-locking behavior of neurons under periodic forcing. We find these tongues for both class-1 and class-2 excitable neurons in both deterministic and noisy regimes.
Thorn, David A; Li, Jiuzhou; Qiu, Yanyan; Li, Jun-Xu
2016-09-01
Methamphetamine abuse remains an alarming public heath challenge, with no approved pharmacotherapies available. Agmatine is a naturally occurring cationic polyamine that has previously been shown to attenuate the rewarding and psychomotor-sensitizing effects of methamphetamine. This study examined the effects of agmatine on the discriminative stimulus and hyperthermic effects of methamphetamine. Adult male rats were trained to discriminate 0.32 mg/kg methamphetamine from saline. Methamphetamine dose dependently increased drug-associated lever responding. The nonselective dopamine receptor antagonist haloperidol (0.1 mg/kg) significantly attenuated the discriminative stimulus effects of methamphetamine (5.9-fold rightward shift). Agmatine (10-100 mg/kg) did not substitute for methamphetamine, but significantly attenuated the stimulus effects of methamphetamine, leading to a maximum of a 3.5-fold rightward shift. Acute 10 mg/kg methamphetamine increased the rectal temperature by a maximum of 1.96±0.17°C. Agmatine (10-32 mg/kg) pretreatment significantly attenuated the hyperthermic effect of methamphetamine. Agmatine (10 mg/kg) also significantly reversed methamphetamine-induced temperature increase. Together, these results support further exploration of the value that agmatine may have for the treatment of methamphetamine abuse and overdose.
Bustamante, D; Paeile, C; Willer, J C; Le Bars, D
1996-03-01
A C-fiber reflex elicited by electrical stimulation within the territory of the sural nerve, was recorded from the ipsilateral biceps femoris muscle in anesthetized rats. The temporal evolution of the response was studied using a constant stimulus intensity (3 x threshold) and recruitment curves were built by varying stimulus intensity from 0 to 7 x threshold. The i.v. administration of aspirin, indomethacin, ketoprofen, paracetamol (= acetaminophen) and lysine clonixinate resulted in dose-dependent depressions of the C-fiber reflex by up to 30 to 40%. By contrast, saline was ineffective. High doses of the effective drugs that produced large disturbances in heart rate and/or acid-base equilibrium were not considered in the pharmacological analysis. When a constant level of stimulation was used, different dose-dependent profiles of drug action were observed. Aspirin induced a slow and gradual depression, although indomethacin, ketoprofen and paracetamol produced a peak effect within the first 10-min period and then reached a steady state phase for up to 30 min. The depressive effects of lysine clonixinate appeared more stable. When recruitment curves were built with a range of nociceptive stimulus intensities, all the drugs produced a dose-dependent decrease in the slopes and the areas under the recruitment curves without any major modification in the thresholds. The order of potency was the same for both stimulation paradigms, e.g., aspirin lysine clonixinate = ketoprofen < indomethacin. It is concluded that NSAID elicit significant antinociceptive effects at a central level, which do not depend on the existence of a hyperalgesic or inflammatory state.
Brielmann, Aenne A; Vale, Lauren; Pelli, Denis G
2017-12-01
Over time, how does beauty develop and decay? Common sense suggests that beauty is intensely felt only after prolonged experience of the object. Here, we present one of various stimuli for a variable duration (1-30 s), measure the observers' pleasure over time, and, finally, ask whether they felt beauty. On each trial, participants (N = 21) either see an image that they had chosen as "movingly beautiful," see an image with prerated valence, or suck a candy. During the stimulus and a further 60 s, participants rate pleasure continuously using a custom touchscreen web app, EmotionTracker.com. After each trial, participants judge whether they felt beauty. Across all stimulus kinds, durations, and beauty responses, the dynamic pleasure rating has a stereotypical time course that is well fit by a one-parameter model with a brief exponential onset (roughly 2.5 s), a sustained plateau during stimulus presentation, and a long exponential decay (roughly 70 s). Across conditions, only the plateau amplitude varies. Beauty and pleasure amplitude are nearly independent of stimulus duration. The final beauty rating is positively correlated with pleasure amplitude (r = 0.60), and nearly independent of duration (r = 0.10). Beauty's independence from duration is unlike Bentham's 18th-century notion of value (utility), which he supposed to depend on the product of pleasure amplitude and duration. Participants report having felt pleasure as strongly after a mere 1 s stimulus as after longer durations, up to 30 s. Thus, we find that amplitude of pleasure is independent of stimulus duration.
Anticipating Stimulus Money for Campus Projects, Colleges Get "Shovel Ready"
Carlson, Scott
2009-01-01
Help for colleges may be on the way in the $825-billion stimulus package being pressed by Congressional leaders. The bill that House Democrats introduced this month includes $7-billion for higher-education modernization, renovation, and repair that could kick-start projects like upgrading heating and cooling systems, fixing roofs, and doing…
Chow, Stephanie S.; Romo, Ranulfo; Brody, Carlos D.
2009-01-01
In a complex world, a sensory cue may prompt different actions in different contexts. A laboratory example of context-dependent sensory processing is the two-stimulus-interval discrimination task. In each trial, a first stimulus (f1) must be stored in short-term memory and later compared with a second stimulus (f2), for the animal to come to a binary decision. Prefrontal cortex (PFC) neurons need to interpret the f1 information in one way (perhaps with a positive weight) and the f2 informatio...
Borucki, Ewa; Berg, Bruce G
2017-05-01
This study investigated the psychophysical effects of distortion products in a listening task traditionally used to estimate the bandwidth of phase sensitivity. For a 2000 Hz carrier, estimates of modulation depth necessary to discriminate amplitude modulated (AM) tones and quasi-frequency modulated (QFM) were measured in a two interval forced choice task as a function modulation frequency. Temporal modulation transfer functions were often non-monotonic at modulation frequencies above 300 Hz. This was likely to be due to a spectral cue arising from the interaction of auditory distortion products and the lower sideband of the stimulus complex. When the stimulus duration was decreased from 200 ms to 20 ms, thresholds for low-frequency modulators rose to near-chance levels, whereas thresholds in the region of non-monotonicities were less affected. The decrease in stimulus duration appears to hinder the listener's ability to use temporal cues in order to discriminate between AM and QFM, whereas spectral information derived from distortion product cues appears more resilient. Copyright © 2017. Published by Elsevier B.V.
Oscillatory fluid flow influences primary cilia and microtubule mechanics.
Espinha, Lina C; Hoey, David A; Fernandes, Paulo R; Rodrigues, Hélder C; Jacobs, Christopher R
2014-07-01
Many tissues are sensitive to mechanical stimuli; however, the mechanotransduction mechanism used by cells remains unknown in many cases. The primary cilium is a solitary, immotile microtubule-based extension present on nearly every mammalian cell which extends from the basal body. The cilium is a mechanosensitive organelle and has been shown to transduce fluid flow-induced shear stress in tissues, such as the kidney and bone. The majority of microtubules assemble from the mother centriole (basal body), contributing significantly to the anchoring of the primary cilium. Several studies have attempted to quantify the number of microtubules emanating from the basal body and the results vary depending on the cell type. It has also been shown that cellular response to shear stress depends on microtubular integrity. This study hypothesizes that changing the microtubule attachment of primary cilia in response to a mechanical stimulus could change primary cilia mechanics and, possibly, mechanosensitivity. Oscillatory fluid flow was applied to two different cell types and the microtubule attachment to the ciliary base was quantified. For the first time, an increase in microtubules around primary cilia both with time and shear rate in response to oscillatory fluid flow stimulation was demonstrated. Moreover, it is presented that the primary cilium is required for this loading-induced cellular response. This study has demonstrated a new role for the cilium in regulating alterations in the cytoplasmic microtubule network in response to mechanical stimulation, and therefore provides a new insight into how cilia may regulate its mechanics and thus the cells mechanosensitivity. Copyright © 2014 Wiley Periodicals, Inc.
Signal detection by active, noisy hair bundles
O'Maoiléidigh, Dáibhid; Salvi, Joshua D.; Hudspeth, A. J.
2018-05-01
Vertebrate ears employ hair bundles to transduce mechanical movements into electrical signals, but their performance is limited by noise. Hair bundles are substantially more sensitive to periodic stimulation when they are mechanically active, however, than when they are passive. We developed a model of active hair-bundle mechanics that predicts the conditions under which a bundle is most sensitive to periodic stimulation. The model relies only on the existence of mechanotransduction channels and an active adaptation mechanism that recloses the channels. For a frequency-detuned stimulus, a noisy hair bundle's phase-locked response and degree of entrainment as well as its detection bandwidth are maximized when the bundle exhibits low-amplitude spontaneous oscillations. The phase-locked response and entrainment of a bundle are predicted to peak as functions of the noise level. We confirmed several of these predictions experimentally by periodically forcing hair bundles held near the onset of self-oscillation. A hair bundle's active process amplifies the stimulus preferentially over the noise, allowing the bundle to detect periodic forces less than 1 pN in amplitude. Moreover, the addition of noise can improve a bundle's ability to detect the stimulus. Although, mechanical activity has not yet been observed in mammalian hair bundles, a related model predicts that active but quiescent bundles can oscillate spontaneously when they are loaded by a sufficiently massive object such as the tectorial membrane. Overall, this work indicates that auditory systems rely on active elements, composed of hair cells and their mechanical environment, that operate on the brink of self-oscillation.
Utilization of reward-prospect enhances preparatory attention and reduces stimulus conflict
van den Berg, Berry; Krebs, Ruth M.; Lorist, Monicque M.; Woldorff, Marty G.
The prospect of gaining money is an incentive widely at play in the real world. Such monetary motivation might have particularly strong influence when the cognitive system is challenged, such as when needing to process conflicting stimulus inputs. Here, we employed manipulations of reward-prospect
Uncovering effects of self-control and stimulus-driven action selection on the sense of agency.
Wang, Yuru; Damen, Tom G E; Aarts, Henk
2017-10-01
The sense of agency refers to feelings of causing one's own action and resulting effect. Previous research indicates that voluntary action selection is an important factor in shaping the sense of agency. Whereas the volitional nature of the sense of agency is well documented, the present study examined whether agency is modulated when action selection shifts from self-control to a more automatic stimulus-driven process. Seventy-two participants performed an auditory Simon task including congruent and incongruent trials to generate automatic stimulus-driven vs. more self-control driven action, respectively. Responses in the Simon task produced a tone and agency was assessed with the intentional binding task - an implicit measure of agency. Results showed a Simon effect and temporal binding effect. However, temporal binding was independent of congruency. These findings suggest that temporal binding, a window to the sense of agency, emerges for both automatic stimulus-driven actions and self-controlled actions. Copyright © 2017 Elsevier Inc. All rights reserved.
Influence of stimulus intensity on the soleus H-reflex amplitude and modulation during locomotion
DEFF Research Database (Denmark)
Simonsen, Erik B; Alkjær, Tine; Raffalt, Peter C
2013-01-01
-reflex methodology itself. Accordingly, the purpose of the present study was to study the effect on the soleus H-reflex during walking and running using stimulus intensities normally considered too high (up to 45% Mmax). Using M-waves of 25-45% Mmax as opposed to 5-25% Mmax showed a significant suppression...... of the peak H-reflex during the stance phase of walking, while no changes were observed during running. No differences were observed regarding modulation pattern. So a possible use of too high stimulus intensity cannot explain the differences mentioned. The surprising result in running may be explained...
Gehring, Katrin B.; Heufelder, Karin; Feige, Janina; Bauer, Paul; Dyck, Yan; Ehrhardt, Lea; Kühnemund, Johannes; Bergmann, Anja; Göbel, Josefine; Isecke, Marlene
2016-01-01
The transcription factor cAMP-response element-binding protein (CREB) is involved in neuronal plasticity. Phosphorylation activates CREB and an increased level of phosphorylated CREB is regarded as an indicator of CREB-dependent transcriptional activation. In honeybees (Apis mellifera) we recently demonstrated a particular high abundance of the phosphorylated honeybee CREB homolog (pAmCREB) in the central brain and in a subpopulation of mushroom body neurons. We hypothesize that these high pAmCREB levels are related to learning and memory formation. Here, we tested this hypothesis by analyzing brain pAmCREB levels in classically conditioned bees and bees experiencing unpaired presentations of conditioned stimulus (CS) and unconditioned stimulus (US). We demonstrate that both behavioral protocols display differences in memory formation but do not alter the level of pAmCREB in bee brains directly after training. Nevertheless, we report that bees responding to the CS during unpaired stimulus presentations exhibit higher levels of pAmCREB than nonresponding bees. In addition, Trichostatin A, a histone deacetylase inhibitor that is thought to enhance histone acetylation by CREB-binding protein, increases the bees’ CS responsiveness. We conclude that pAmCREB is involved in gating a bee's behavioral response driven by an external stimulus. PMID:27084927
Mechanical sensitivity of Piezo1 ion channels can be tuned by cellular membrane tension
Lewis, Amanda H; Grandl, Jörg
2015-01-01
Piezo1 ion channels mediate the conversion of mechanical forces into electrical signals and are critical for responsiveness to touch in metazoans. The apparent mechanical sensitivity of Piezo1 varies substantially across cellular environments, stimulating methods and protocols, raising the fundamental questions of what precise physical stimulus activates the channel and how its stimulus sensitivity is regulated. Here, we measured Piezo1 currents evoked by membrane stretch in three patch configurations, while simultaneously visualizing and measuring membrane geometry. Building on this approach, we developed protocols to minimize resting membrane curvature and tension prior to probing Piezo1 activity. We find that Piezo1 responds to lateral membrane tension with exquisite sensitivity as compared to other mechanically activated channels and that resting tension can drive channel inactivation, thereby tuning overall mechanical sensitivity of Piezo1. Our results explain how Piezo1 can function efficiently and with adaptable sensitivity as a sensor of mechanical stimulation in diverse cellular contexts. DOI: http://dx.doi.org/10.7554/eLife.12088.001 PMID:26646186
Does supernormal stimulus influence parental behaviour of the cuckoo's host?
Czech Academy of Sciences Publication Activity Database
Grim, T.; Honza, Marcel
2001-01-01
Roč. 49, č. 4 (2001), s. 322-329 ISSN 0340-5443 R&D Projects: GA AV ČR IAA6087801; GA AV ČR KSK2005601; GA MŠk VS96019 Institutional research plan: CEZ:AV0Z6093917 Keywords : brood parasitism * supernormal stimulus * parental care Subject RIV: EG - Zoology Impact factor: 2.353, year: 2001
Stimulus-Response Theory of Finite Automata, Technical Report No. 133.
Suppes, Patrick
The central aim of this paper and its projected successors is to prove in detail that stimulus-response theory, or at least a mathematically precise version, can give an account of the learning of many phrase-structure grammars. Section 2 is concerned with standard notions of finite and probabilistic automata. An automaton is defined as a device…
Wittevrongel, Benjamin; Van Wolputte, Elia; Van Hulle, Marc M
2017-11-08
When encoding visual targets using various lagged versions of a pseudorandom binary sequence of luminance changes, the EEG signal recorded over the viewer's occipital pole exhibits so-called code-modulated visual evoked potentials (cVEPs), the phase lags of which can be tied to these targets. The cVEP paradigm has enjoyed interest in the brain-computer interfacing (BCI) community for the reported high information transfer rates (ITR, in bits/min). In this study, we introduce a novel decoding algorithm based on spatiotemporal beamforming, and show that this algorithm is able to accurately identify the gazed target. Especially for a small number of repetitions of the coding sequence, our beamforming approach significantly outperforms an optimised support vector machine (SVM)-based classifier, which is considered state-of-the-art in cVEP-based BCI. In addition to the traditional 60 Hz stimulus presentation rate for the coding sequence, we also explore the 120 Hz rate, and show that the latter enables faster communication, with a maximal median ITR of 172.87 bits/min. Finally, we also report on a transition effect in the EEG signal following the onset of the stimulus sequence, and recommend to exclude the first 150 ms of the trials from decoding when relying on a single presentation of the stimulus sequence.
Nöstl, Anatole; Marsh, John E; Sörqvist, Patrik
2014-01-01
Participants were requested to respond to a sequence of visual targets while listening to a well-known lullaby. One of the notes in the lullaby was occasionally exchanged with a pattern deviant. Experiment 1 found that deviants capture attention as a function of the pitch difference between the deviant and the replaced/expected tone. However, when the pitch difference between the expected tone and the deviant tone is held constant, a violation to the direction-of-pitch change across tones can also capture attention (Experiment 2). Moreover, in more complex auditory environments, wherein it is difficult to build a coherent neural model of the sound environment from which expectations are formed, deviations can capture attention but it appears to matter less whether this is a violation from a specific stimulus or a violation of the current direction-of-change (Experiment 3). The results support the expectation violation account of auditory distraction and suggest that there are at least two different expectations that can be violated: One appears to be bound to a specific stimulus and the other would seem to be bound to a more global cross-stimulus rule such as the direction-of-change based on a sequence of preceding sound events. Factors like base-rate probability of tones within the sound environment might become the driving mechanism of attentional capture--rather than violated expectations--in complex sound environments.
Robust preprocessing for stimulus-based functional MRI of the moving fetus.
You, Wonsang; Evangelou, Iordanis E; Zun, Zungho; Andescavage, Nickie; Limperopoulos, Catherine
2016-04-01
Fetal motion manifests as signal degradation and image artifact in the acquired time series of blood oxygen level dependent (BOLD) functional magnetic resonance imaging (fMRI) studies. We present a robust preprocessing pipeline to specifically address fetal and placental motion-induced artifacts in stimulus-based fMRI with slowly cycled block design in the living fetus. In the proposed pipeline, motion correction is optimized to the experimental paradigm, and it is performed separately in each phase as well as in each region of interest (ROI), recognizing that each phase and organ experiences different types of motion. To obtain the averaged BOLD signals for each ROI, both misaligned volumes and noisy voxels are automatically detected and excluded, and the missing data are then imputed by statistical estimation based on local polynomial smoothing. Our experimental results demonstrate that the proposed pipeline was effective in mitigating the motion-induced artifacts in stimulus-based fMRI data of the fetal brain and placenta.
Lien, Mei-Ching; Proctor, Robert W; Allen, Philip A
2002-04-01
Four experiments examined whether the psychological refractory period (PRP) effect can be eliminated with ideomotor compatible (IM) but not stimulus-response compatible (SR) tasks, as reported by A. G. Greenwald and H. G. Shulman (1973). Their tasks were used: a left or right movement to a left- or right-pointing arrow (IM) or to the word left or right (SR) for Task 1; saying "A" or "B" (IM) or "1" or "2" (SR) to an auditory A or B for Task 2. The stimulus onset asynchronies were 0, 100, 200, 300, 500, and 1,000 ms in Experiment 1, and only 0, 100, 200, and 1,000 ms in Experiments 2-4. The arrow was in the center of the screen in Experiments 1-3 and to the left or right in Experiment 4. As in Greenwald and Shulman's Experiment 2, the instructions stated that most often the 2 stimuli would be presented simultaneously. A PRP effect was obtained in all conditions, most likely because response-selection decisions are required even for IM tasks.
Poverty of the stimulus revisited.
Berwick, Robert C; Pietroski, Paul; Yankama, Beracah; Chomsky, Noam
2011-01-01
A central goal of modern generative grammar has been to discover invariant properties of human languages that reflect "the innate schematism of mind that is applied to the data of experience" and that "might reasonably be attributed to the organism itself as its contribution to the task of the acquisition of knowledge" (Chomsky, 1971). Candidates for such invariances include the structure dependence of grammatical rules, and in particular, certain constraints on question formation. Various "poverty of stimulus" (POS) arguments suggest that these invariances reflect an innate human endowment, as opposed to common experience: Such experience warrants selection of the grammars acquired only if humans assume, a priori, that selectable grammars respect substantive constraints. Recently, several researchers have tried to rebut these POS arguments. In response, we illustrate why POS arguments remain an important source of support for appeal to a priori structure-dependent constraints on the grammars that humans naturally acquire. Copyright © 2011 Cognitive Science Society, Inc.
Stimulus-dependent modulation of spike burst length in cat striate cortical cells.
DeBusk, B C; DeBruyn, E J; Snider, R K; Kabara, J F; Bonds, A B
1997-07-01
Burst activity, defined by groups of two or more spikes with intervals of cats. Bursting varied broadly across a population of 507 simple and complex cells. Half of this population had > or = 42% of their spikes contained in bursts. The fraction of spikes in bursts did not vary as a function of average firing rate and was stationary over time. Peaks in the interspike interval histograms were found at both 3-5 ms and 10-30 ms. In many cells the locations of these peaks were independent of firing rate, indicating a quantized control of firing behavior at two different time scales. The activity at the shorter time scale most likely results from intrinsic properties of the cell membrane, and that at the longer scale from recurrent network excitation. Burst frequency (bursts per s) and burst length (spikes per burst) both depended on firing rate. Burst frequency was essentially linear with firing rate, whereas burst length was a nonlinear function of firing rate and was also governed by stimulus orientation. At a given firing rate, burst length was greater for optimal orientations than for nonoptimal orientations. No organized orientation dependence was seen in bursts from lateral geniculate nucleus cells. Activation of cortical contrast gain control at low response amplitudes resulted in no burst length modulation, but burst shortening at optimal orientations was found in responses characterized by supersaturation. At a given firing rate, cortical burst length was shortened by microinjection of gamma-aminobutyric acid (GABA), and bursts became longer in the presence of N-methyl-bicuculline, a GABA(A) receptor blocker. These results are consistent with a model in which responses are reduced at nonoptimal orientations, at least in part, by burst shortening that is mediated by GABA. A similar mechanism contributes to response supersaturation at high contrasts via recruitment of inhibitory responses that are tuned to adjacent orientations. Burst length modulation can serve
Auditory stimulus discrimination recorded in dogs, as indicated by mismatch negativity (MMN).
Howell, Tiffani J; Conduit, Russell; Toukhsati, Samia; Bennett, Pauleen
2012-01-01
Dog cognition research tends to rely on behavioural response, which can be confounded by obedience or motivation, as the primary means of indexing dog cognitive abilities. A physiological method of measuring dog cognitive processing would be instructive and could complement behavioural response. Electroencephalogram (EEG) has been used in humans to study stimulus processing, which results in waveforms called event-related potentials (ERPs). One ERP component, mismatch negativity (MMN), is a negative deflection approximately 160-200 ms after stimulus onset, which may be related to change detection from echoic sensory memory. We adapted a minimally invasive technique to record MMN in dogs. Dogs were exposed to an auditory oddball paradigm in which deviant tones (10% probability) were pseudo-randomly interspersed throughout an 8 min sequence of standard tones (90% probability). A significant difference in MMN ERP amplitude was observed after the deviant tone in comparison to the standard tone, t5 = -2.98, p = 0.03. This difference, attributed to discrimination of an unexpected stimulus in a series of expected stimuli, was not observed when both tones occurred 50% of the time, t1 = -0.82, p > 0.05. Dogs showed no evidence of pain or distress at any point. We believe this is the first illustration of MMN in a group of dogs and anticipate that this technique may provide valuable insights in cognitive tasks such as object discrimination. Copyright © 2011 Elsevier B.V. All rights reserved.
International Nuclear Information System (INIS)
Ogura, Tatsuo; Miyamoto, Masanori; Budiyono, Agung; Nakamura, Katsuhiro
2007-01-01
Fractal magnetoconductance fluctuations are often observed in experiments on ballistic quantum dots. Although the analysis of the exact self-affine fractal has been given by the semiclassical theory using self-similar periodic orbits in systems with a soft-walled potential with a saddle, there has been no corresponding quantum mechanical investigation. We numerically calculate the quantum conductance with use of the recursive Green's function method applied to open cavities characterized by a Henon-Heiles type potential. The conductance fluctuations show exact self-affinity just as in some of the experimental observations. The enlargement factor for the horizontal axis can be explained by the scaling factor of the area of self-similar periodic orbits, and therefore be attributed to the curvature of the saddle in the cavity potential. The fractal dimension obtained through the box counting method agrees with those evaluated with use of the Hurst exponent, and coincides with the semiclassical prediction. We further investigate the variation of the fractal dimension by changing the control parameters between the classical and quantum domains. (fast track communication)
de Rose, Julio C.; Hidalgo, Matheus; Vasconcellos, Mariliz
2013-01-01
Variation in baseline controlling relations is suggested as one of the factors determining variability in stimulus equivalence outcomes. This study used single- comparison trials attempting to control such controlling relations. Four children learned AB, BC, and CD conditional discriminations, with 2 samples and 2 comparison stimuli. In Condition…
Hygge, S
1976-06-01
Four groups with 16 observers each participated in a differential, vicarious conditioning experiment with skin conductance responses as the dependent variable. The information available to the observer about the model's unconditioned stimulus and response was varied in a 2 X 2 factorial design. Results clearly showed that information about the model's unconditioned stimulus (a high or low dB level) was not necessary for vicarious instigation, but that information about the unconditioned response (a high or low emotional aversiveness) was necessary. Data for conditioning of responses showed almost identical patterns to those for vicarious instigation. To explain the results, a distinction between factors necessary for the development and elicitation of vicariously instigated responses was introduced, and the effectiveness of information about the model's response on the elicitation of vicariously instigated responses was considered in terms of an expansion of Bandura's social learning theory.
International Nuclear Information System (INIS)
Fox, P.T.; Raichle, M.E.
1984-01-01
The purpose of this investigation was to determine the relationship between the repetition rate of a simple sensory stimulus and regional cerebral blood flow (rCBF) in the human brain. Positron emission tomography (PET), using intravenously administered H 2 ( 15 )O as the diffusible blood-flow tracer, was employed for all CBF measurements. The use of H 2 ( 15 )O with PET allowed eight CBF measurements to be made in rapid sequence under multiple stimulation conditions without removing the subject from the tomograph. Nine normal volunteers each underwent a series of eight H2( 15 )O PET measurements of CBF. Initial and final scans were made during visual deprivation. The six intervening scans were made during visual activation with patterned-flash stimuli given in random order at 1.0-, 3.9-, 7.8-, 15.5-, 33.1-, and 61-Hz repetition rates. The region of greatest rCBF increase was determined. Within this region the rCBF was determined for every test condition and then expressed as the percentage change from the value of the initial unstimulated scan (rCBF% delta). In every subject, striate cortex rCBF% delta varied systematically with stimulus rate. Between 0 and 7.8 Hz, rCBF% delta was a linear function of stimulus repetition rate. The rCBF response peaked at 7.8 Hz and then declined. The rCBF% delta during visual stimulation was significantly greater than that during visual deprivation for every stimulus rate except 1.0 Hz. The anatomical localization of the region of peak rCBF response was determined for every subject to be the mesial occipital lobes along the calcarine fissure, primary visual cortex. Stimulus rate is a significant determinant of rCBF response in the visual cortex. Investigators of brain responses to selective activation procedures should be aware of the potential effects of stimulus rate on rCBF and other measurements of cerebral metabolism
Computation-Guided Design of a Stimulus-Responsive Multienzyme Supramolecular Assembly.
Yang, Lu; Dolan, Elliott M; Tan, Sophia K; Lin, Tianyun; Sontag, Eduardo D; Khare, Sagar D
2017-10-18
The construction of stimulus-responsive supramolecular complexes of metabolic pathway enzymes, inspired by natural multienzyme assemblies (metabolons), provides an attractive avenue for efficient and spatiotemporally controllable one-pot biotransformations. We have constructed a phosphorylation- and optically responsive metabolon for the biodegradation of the environmental pollutant 1,2,3-trichloropropane. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
Mechanical and tribological properties of a-C/a-C:Ti multilayer films with various bilayer periods
Energy Technology Data Exchange (ETDEWEB)
Bai, W.Q.; Cai, J.B.; Wang, X.L., E-mail: wangxl@zju.edu.cn; Wang, D.H.; Gu, C.D.; Tu, J.P., E-mail: tujp@zju.edu.cn
2014-05-02
Thick a-C/a-C:Ti multilayer films with bilayer periods of 12–70 nm were deposited on Ti6Al4V alloy substrate by means of closed field unbalance magnetron sputtering. The morphology and microstructure of the multilayer films were investigated by scanning electron microscopy, high resolution transmission electron microscopy and X-ray photoelectron spectroscopy. Nanocrystalline TiC was distributed in the a-C:Ti layer and at the interface between the two adjacent layers. The mechanical and tribological properties were evaluated by Rockwell and scratch tests, a nanoindentor and a ball-on-disk tribometer. The multilayer film with a bilayer period of 12 nm showed the highest adhesion strength, hardness (26 GPa) and elastic modulus (232 GPa); it also had the lowest average coefficient of friction (0.09) and a wear rate of 8.06 × 10{sup −17} m{sup 3} N{sup −1} m{sup −1}. - Highlights: • a-C/a-C:Ti multilayers with various bilayer periods were prepared. • Nanocrystalline TiCs were confirmed in the a-C:Ti layer and at the interface. • These multilayers show fine ability to comply with substrate deformation. • The multilayer with a bilayer period of 12 nm exhibits the best properties.
Measurement of erythema and tanning responses in human skin using a tri-stimulus colorimeter.
Seitz, J C; Whitmore, C G
1988-01-01
A 'Minolta Tri-Stimulus Colorimeter II' was evaluated for obtaining objective measurements of early changes in erythema and tanning. The meter showed a subtle, continuous transition between the primary erythematous response and the delayed tanning of skin which was below the visual threshold for detection. Thereafter, the a* (redness) value of the meter showed a significant linear correlation with the dermatologist's perception of erythema while the b* (yellow) value showed a significant correlation with the perception of tanning. This capability of the tri-stimulus colorimeter to simultaneously evaluate the hue and saturation of skin color affords an improved opportunity to quantitate the transition from erythema to tanning without subjective bias.
Zaidel, Adam; DeAngelis, Gregory C; Angelaki, Dora E
2017-09-28
Trial-by-trial correlations between neural responses and choices (choice probabilities) are often interpreted to reflect a causal contribution of neurons to task performance. However, choice probabilities may arise from top-down, rather than bottom-up, signals. We isolated distinct sensory and decision contributions to single-unit activity recorded from the dorsal medial superior temporal (MSTd) and ventral intraparietal (VIP) areas of monkeys during perception of self-motion. Superficially, neurons in both areas show similar tuning curves during task performance. However, tuning in MSTd neurons primarily reflects sensory inputs, whereas choice-related signals dominate tuning in VIP neurons. Importantly, the choice-related activity of VIP neurons is not predictable from their stimulus tuning, and these factors are often confounded in choice probability measurements. This finding was confirmed in a subset of neurons for which stimulus tuning was measured during passive fixation. Our findings reveal decoupled stimulus and choice signals in the VIP area, and challenge our understanding of choice signals in the brain.Choice-related signals in neuronal activity may reflect bottom-up sensory processes, top-down decision-related influences, or a combination of the two. Here the authors report that choice-related activity in VIP neurons is not predictable from their stimulus tuning, and that dominant choice signals can bias the standard metric of choice preference (choice probability).
Directory of Open Access Journals (Sweden)
Jacob Westfall
2017-03-01
Full Text Available Most functional magnetic resonance imaging (fMRI experiments record the brain’s responses to samples of stimulus materials (e.g., faces or words. Yet the statistical modeling approaches used in fMRI research universally fail to model stimulus variability in a manner that affords population generalization, meaning that researchers’ conclusions technically apply only to the precise stimuli used in each study, and cannot be generalized to new stimuli. A direct consequence of this stimulus-as-fixed-effect fallacy is that the majority of published fMRI studies have likely overstated the strength of the statistical evidence they report. Here we develop a Bayesian mixed model (the random stimulus model; RSM that addresses this problem, and apply it to a range of fMRI datasets. Results demonstrate considerable inflation (50-200% in most of the studied datasets of test statistics obtained from standard “summary statistics”-based approaches relative to the corresponding RSM models. We demonstrate how RSMs can be used to improve parameter estimates, properly control false positive rates, and test novel research hypotheses about stimulus-level variability in human brain responses.
Directory of Open Access Journals (Sweden)
Xie Zhi-Yang
2018-02-01
Full Text Available Acid-sensing ion channel 1a (ASIC1a participates in human intervertebral disc degeneration (IVDD and regulates the destiny of nucleus pulposus cells (NPCs in acid stimulus. However, the mechanism of ASIC1a activation and its downstream pathway remain unclear. Endoplasmic reticulum (ER stress also participates in the acid-induced apoptosis of NPCs. The main purpose of this study was to investigate whether there is any connection between ASIC1a and ER stress in an acid-induced nucleus pulposus degeneration model. The IVDs of Sprague-Dawley rats were stained by immunohistochemical staining to evaluate the expression of ASIC1a in normal and degenerated rat nucleus pulposus. ASIC1a expression was also quantified by quantitative real-time-polymerase chain reaction and Western blotting analysis. NPCs were exposed to the culture media with acidity at pH 7.2 and 6.5 for 24 h, with or without 4-phenylbutyrate (4-PBA, a blocker of the ER stress pathway. Cell apoptosis was examined by Annexin V/Propidium Iodide (PI staining and was quantified using flow cytometry analysis. ASIC1a-mediated intracellular calcium was determined by Ca2+ imaging using Fura-2-AM. Acidity-induced changes in ER stress markers were studied using Western blotting analysis. In vivo, ASIC1a expression was upregulated in natural degeneration. In vitro, acid stimulus increased intracellular calcium levels, but this effect was blocked by knockdown of ASIC1a, and this reversal was partly inhibited by 4-PBA. In addition, blockade of ASIC1a reduced expression of ER stress markers, especially the proapoptotic markers. ASIC1a partly regulates ER stress and promotes apoptosis of NPCs under acid stimulus and may be a novel therapeutic target in IVDD.
Xie, Zhi-Yang; Chen, Lu; Zhang, Cong; Liu, Lei; Wang, Feng; Cai, Feng; Wang, Xiao-Hu; Shi, Rui; Sinkemani, Arjun; Yu, Hao-Min; Hong, Xin; Wu, Xiao-Tao
2018-01-01
Acid-sensing ion channel 1a (ASIC1a) participates in human intervertebral disc degeneration (IVDD) and regulates the destiny of nucleus pulposus cells (NPCs) in acid stimulus. However, the mechanism of ASIC1a activation and its downstream pathway remain unclear. Endoplasmic reticulum (ER) stress also participates in the acid-induced apoptosis of NPCs. The main purpose of this study was to investigate whether there is any connection between ASIC1a and ER stress in an acid-induced nucleus pulposus degeneration model. The IVDs of Sprague-Dawley rats were stained by immunohistochemical staining to evaluate the expression of ASIC1a in normal and degenerated rat nucleus pulposus. ASIC1a expression was also quantified by quantitative real-time-polymerase chain reaction and Western blotting analysis. NPCs were exposed to the culture media with acidity at pH 7.2 and 6.5 for 24 h, with or without 4-phenylbutyrate (4-PBA, a blocker of the ER stress pathway). Cell apoptosis was examined by Annexin V/Propidium Iodide (PI) staining and was quantified using flow cytometry analysis. ASIC1a-mediated intracellular calcium was determined by Ca 2+ imaging using Fura-2-AM. Acidity-induced changes in ER stress markers were studied using Western blotting analysis. In vivo , ASIC1a expression was upregulated in natural degeneration. In vitro , acid stimulus increased intracellular calcium levels, but this effect was blocked by knockdown of ASIC1a, and this reversal was partly inhibited by 4-PBA. In addition, blockade of ASIC1a reduced expression of ER stress markers, especially the proapoptotic markers. ASIC1a partly regulates ER stress and promotes apoptosis of NPCs under acid stimulus and may be a novel therapeutic target in IVDD.
Urcuioli, Peter J
2010-10-01
Two experiments tested the assumption of Urcuioli's (2008) theory of pigeons' equivalence-class formation that consistent non-reinforcement of certain stimulus combinations in successive matching juxtaposed with consistent reinforcement of other combinations generates stimulus classes containing the elements of the reinforced combinations. In Experiment 1, pigeons were concurrently trained on symbolic (AB) and two identity (AA and BB) successive tasks in which half of all identity trials ended in non-reinforcement but all AB trials were reinforced, contingent upon either responding or not responding to the comparisons. Subsequent symmetry (BA) probe trials showed evidence of symmetry in one of four pigeons. In Experiment 2, pigeons learned three pair-comparison tasks in which left versus right spatial choices were reinforced after the various sample-comparison combinations comprising AB, AA, and BB conditional discriminations. Non-differentially reinforced BA probe trials following acquisition showed some indication of symmetrical choice responding. The overall results contradict the theoretical predictions derived from Urcuioli (2008) and those from Experiment 2 challenge other stimulus-class analyses as well. Copyright © 2010 Elsevier B.V. All rights reserved.
Minimum period and the gap in periods of Cataclysmic binaries
International Nuclear Information System (INIS)
Paczynski, B.; Sienkiewicz, R.
1983-01-01
The 81 minute cutoff to the orbital periods of hydrogen-rich cataclysmic binaries is consistent with evolution of those systems being dominated by angular momentum losses due to gravitational radiation. Unfortunately, many uncertainties, mainly poorly known atmospheric opacities below 2000 K, make is physically impossible to verify the quadrupole formula for gravitational radiation by using the observed cutoff at 81 minutes. The upper boundary of the gap in orbital periods observed at about 3 hours is almost certainly due to enhanced angular momentum losses from cataclysmic binaries which have longer periods. The physical mechanism of those losses is not identified, but a possible importance of stellar winds is pointed out. The lower boundary of the gap may be explained with the oldest cataclysmic binaries, whose periods evolved past the minimum at 81 minutes and reached the value of 2 hours within about 12 x 10 9 years after the binary had formed. Those binaries should have secondary components of only 0.02 solar masses, and their periods could be used to estimate ages of the oldest cataclysmic stars, and presumably the age of Galaxy. An alternative explanation for the gap requires that binaries should be detached while crossing the gap. A possible mechanism for this phenomenon is discussed. It requires the secondary components to be about 0.2 solar masses in the binaries just below the gap
DEFF Research Database (Denmark)
Jadidi, F; Wang, K; Arendt-Nielsen, Lars
2009-01-01
Objective: Examine the effect of stimulus duration as well as stimulus intensity and level of muscle contraction on the inhibitory responses in human jaw-closing muscles. Design: The inhibitory jaw-reflexes, ES1 and ES2, were recorded in the surface electromyogram (EMG) of masseter and temporal...
An adaptive neural mechanism for acoustic motion perception with varying sparsity
DEFF Research Database (Denmark)
Shaikh, Danish; Manoonpong, Poramate
2017-01-01
extracts directional information via a model of the peripheral auditory system of lizards. The mechanism uses only this directional information obtained via specific motor behaviour to learn the angular velocity of unoccluded sound stimuli in motion. In nature however the stimulus being tracked may...
Directory of Open Access Journals (Sweden)
Kawai Leung
2016-12-01
Full Text Available A goal of many sensorimotor studies is to quantify the stimulus-behavioral response relation for specific organisms and specific sensory stimuli. This is especially important to do in the context of painful stimuli since most animals in these studies cannot easily communicate to us their perceived levels of such noxious stimuli. Thus progress on studies of nociception and pain-like responses in animal models depends crucially on our ability to quantitatively and objectively infer the sensed levels of these stimuli from animal behaviors. Here we develop a quantitative model to infer the perceived level of heat stimulus from the stereotyped escape response of individual nematodes Caenorhabditis elegans stimulated by an IR laser. The model provides a method for quantification of analgesic-like effects of chemical stimuli or genetic mutations in C. elegans. We test ibuprofen-treated worms and a TRPV (transient receptor potential mutant, and we show that the perception of heat stimuli for the ibuprofen treated worms is lower than the wild-type. At the same time, our model shows that the mutant changes the worm's behavior beyond affecting the thermal sensory system. Finally, we determine the stimulus level that best distinguishes the analgesic-like effects and the minimum number of worms that allow for a statistically significant identification of these effects.
Perceptual stimulus-A Bayesian-based integration of multi-visual-cue approach and its application
Institute of Scientific and Technical Information of China (English)
XUE JianRu; ZHENG NanNing; ZHONG XiaoPin; PING LinJiang
2008-01-01
With the view that visual cue could be taken as a kind of stimulus, the study of the mechanism in the visual perception process by using visual cues in their probabilistic representation eventually leads to a class of statistical integration of multiple visual cues (IMVC) methods which have been applied widely in perceptual grouping, video analysis, and other basic problems in computer vision. In this paper, a survey on the basic ideas and recent advances of IMVC methods is presented, and much focus is on the models and algorithms of IMVC for video analysis within the framework of Bayesian estimation. Furthermore, two typical problems in video analysis, robust visual tracking and "switching problem" in multi-target tracking (MTT) are taken as test beds to verify a series of Bayesian-based IMVC methods proposed by the authors. Furthermore, the relations between the statistical IMVC and the visual per-ception process, as well as potential future research work for IMVC, are discussed.
An Appetitive Conditioned Stimulus Enhances Fear Acquisition and Impairs Fear Extinction
Leung, Hiu T.; Holmes, Nathan M.; Westbrook, R. Frederick
2016-01-01
Four experiments used between- and within-subject designs to examine appetitive-aversive interactions in rats. Experiments 1 and 2 examined the effect of an excitatory appetitive conditioned stimulus (CS) on acquisition and extinction of conditioned fear. In Experiment 1, a CS shocked in a compound with an appetitive excitor (i.e., a stimulus…
"Tunnel Vision": A Possible Keystone Stimulus Control Deficit in Autistic Children.
Rincover, Arnold; And Others
1986-01-01
Three autistic boys (ages 9-13) were trained to select a card containing a stimulus array comprised of three visual cues. Decreased distance between cues resulted in responses to more cues, increased distance to fewer cues. Distances did not affect the responding of children matched for mental and chronological age. (Author/JW)
Finite element modeling of the neuron-electrode interface: stimulus transfer and geometry
Buitenweg, Jan R.; Rutten, Wim; Marani, Enrico
1999-01-01
The relation between stimulus transfer and the geometry of the neuron-electrode interface can not be determined properly using electrical equivalent circuits, since current that flows from the sealing gap through the neuronal membrane is difficult to model in these circuits. Therefore, finite
International Nuclear Information System (INIS)
Savage, Gordon J.; Zhang, Xufang; Son, Young Kap; Pandey, Mahesh D.
2016-01-01
Resonance in a dynamic system is to be avoided since it often leads to impaired performance, overstressing, fatigue fracture and adverse human reactions. Thus, it is necessary to know the modal frequencies and ensure they do not coincide with any applied periodic loadings. For a rotating planar mechanism, the coefficients in the mass and stiffness matrices are periodically varying, and if the underlying geometry and material properties are treated as random variables then the modal frequencies are both position-dependent and probabilistic. The avoidance of resonance is now a complex problem. Herein, free vibration analysis helps determine ranges of modal frequencies that in turn, identify the running speeds of the mechanism to be avoided. This paper presents an efficient and accurate sample-based approach to determine probabilistic minimum and maximum extremes of the fundamental frequencies and the angular positions of their occurrence. Then, given critical lower and upper frequency constraints it is straightforward to determine reliability in terms of probability of exceedance. The novelty of the proposed approach is that the original expensive and implicit mechanistic model is replaced by an explicit meta-model that captures the tolerances of the design variables over the entire range of angular positions: position-dependent eigenvalues can be found easily and quickly. Extreme-value statistics of the modal frequencies and extreme-value statistics of the angular positions are readily computed through MCS. Limit-state surfaces that connect the frequencies to the design variables may be easily constructed. Error analysis identifies three errors and the paper presents ways to control them so the methodology can be sufficiently accurate. A numerical example of a flexible four-bar linkage shows the proposed methodology has engineering applications. The impact of the proposed methodology is two-fold: it presents a safe-side analysis based on free vibration methods to
Tomie, Arthur; Festa, Eugene D; Sparta, Dennis R; Pohorecky, Larissa A
2003-05-01
Two experiments were designed to evaluate whether brief access to a saccharin-ethanol solution would function as an effective unconditioned stimulus (US) in Pavlovian-autoshaping procedures. In these experiments, the insertion of a lever conditioned stimulus (CS) was followed by the brief presentation of a sipper tube containing saccharin-ethanol US solution. Experience with this Pavlovian-autoshaping procedure engendered lever CS-directed autoshaping conditioned responses (CRs) in all rats. In Experiment 1, the concentration of ethanol [0%, 2%, 4%, 6%, or 8% (vol./vol.)] in 0.1% saccharin was systematically increased within subjects across autoshaping sessions to evaluate the relation between a rat's drinking and lever pressing. In Experiment 2, the mean intertrial interval (ITI) duration (60, 90, 120 s) was systematically increased within subjects across autoshaping sessions to evaluate the effect of ITI duration on drinking and lever pressing. A pseudoconditioning control group received lever CS randomly with respect to the saccharin-ethanol US solution. In Experiment 1, lever-press autoshaping CRs developed in all rats, and the tendency of a rat to drink an ethanol concentration was predictive of the performance of lever-press autoshaping CRs. In Experiment 2, longer ITIs induced more lever CS-directed responding, and CS-US paired procedures yielded more lever CS-directed responding than that observed in CS-US random procedures. Saccharin-ethanol is an effective US in Pavlovian-autoshaping procedures, inducing more CS-directed responding than in pseudoconditioning controls receiving CS-US random procedures. More lever CS-directed responding was observed when there was more drinking of the saccharin-ethanol US solution (Experiment 1); when the CS and US were paired, rather than random (Experiment 2); and with longer mean ITI durations (Experiment 2). This pattern of results is consistent with the hypothesis that lever CS-directed responding reflects performance
Utility-based early modulation of processing distracting stimulus information.
Wendt, Mike; Luna-Rodriguez, Aquiles; Jacobsen, Thomas
2014-12-10
Humans are selective information processors who efficiently prevent goal-inappropriate stimulus information to gain control over their actions. Nonetheless, stimuli, which are both unnecessary for solving a current task and liable to cue an incorrect response (i.e., "distractors"), frequently modulate task performance, even when consistently paired with a physical feature that makes them easily discernible from target stimuli. Current models of cognitive control assume adjustment of the processing of distractor information based on the overall distractor utility (e.g., predictive value regarding the appropriate response, likelihood to elicit conflict with target processing). Although studies on distractor interference have supported the notion of utility-based processing adjustment, previous evidence is inconclusive regarding the specificity of this adjustment for distractor information and the stage(s) of processing affected. To assess the processing of distractors during sensory-perceptual phases we applied EEG recording in a stimulus identification task, involving successive distractor-target presentation, and manipulated the overall distractor utility. Behavioral measures replicated previously found utility modulations of distractor interference. Crucially, distractor-evoked visual potentials (i.e., posterior N1) were more pronounced in high-utility than low-utility conditions. This effect generalized to distractors unrelated to the utility manipulation, providing evidence for item-unspecific adjustment of early distractor processing to the experienced utility of distractor information. Copyright © 2014 the authors 0270-6474/14/3416720-06$15.00/0.
Ferrey, Anne E; Burleigh, Tyler J; Fenske, Mark J
2015-01-01
Stimuli that resemble humans, but are not perfectly human-like, are disliked compared to distinctly human and non-human stimuli. Accounts of this "Uncanny Valley" effect often focus on how changes in human resemblance can evoke different emotional responses. We present an alternate account based on the novel hypothesis that the Uncanny Valley is not directly related to 'human-likeness' per se, but instead reflects a more general form of stimulus devaluation that occurs when inhibition is triggered to resolve conflict between competing stimulus-related representations. We consider existing support for this inhibitory-devaluation hypothesis and further assess its feasibility through tests of two corresponding predictions that arise from the link between conflict-resolving inhibition and aversive response: (1) that the pronounced disliking of Uncanny-type stimuli will occur for any image that strongly activates multiple competing stimulus representations, even in the absence of any human-likeness, and (2) that the negative peak of an 'Uncanny Valley' should occur at the point of greatest stimulus-related conflict and not (in the presence of human-likeness) always closer to the 'human' end of a perceptual continuum. We measured affective responses to a set of line drawings representing non-human animal-animal morphs, in which each continuum midpoint was a bistable image (Experiment 1), as well as to sets of human-robot and human-animal computer-generated morphs (Experiment 2). Affective trends depicting classic Uncanny Valley functions occurred for all continua, including the non-human stimuli. Images at continua midpoints elicited significantly more negative affect than images at endpoints, even when the continua included a human endpoint. This illustrates the feasibility of the inhibitory-devaluation hypothesis and the need for further research into the possibility that the strong dislike of Uncanny-type stimuli reflects the negative affective consequences of
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Anne E. Ferrey
2015-03-01
Full Text Available Stimuli that resemble humans, but are not perfectly human-like, are disliked compared to distinctly human and nonhuman stimuli. Accounts of this Uncanny Valley effect often focus on how changes in human resemblance can evoke different emotional responses. We present an alternate account based on the novel hypothesis that the Uncanny Valley is not directly related to ‘human-likeness’ per se, but instead reflects a more general form of stimulus devaluation that occurs when inhibition is triggered to resolve conflict between competing stimulus-related representations. We consider existing support for this inhibitory-devaluation hypothesis and further assess its feasibility through tests of two corresponding predictions that arise from the link between conflict-resolving inhibition and aversive response: 1 that the pronounced disliking of Uncanny-type stimuli will occur for any image that strongly activates multiple competing stimulus representations, even in the absence of any human-likeness, and 2 that the negative peak of an ‘Uncanny Valley’ should occur at the point of greatest stimulus-related conflict and not (in the presence of human-likeness always closer to the ‘human’ end of a perceptual continuum. We measured affective responses to a set of line drawings representing nonhuman animal-animal morphs, in which each continuum midpoint was a bistable image (Exp. 1, as well as to sets of human-robot and human-animal computer-generated morphs (Exp. 2. Affective trends depicting classic Uncanny Valley functions occurred for all continua, including the nonhuman stimuli. Images at continua midpoints elicited significantly more negative affect than images at endpoints, even when the continua included a human endpoint. This illustrates the feasibility of the inhibitory-devaluation hypothesis and the need for further research into the possibility that the strong dislike of Uncanny-type stimuli reflects the negative affective consequences of
Effects of Flexible Dry Electrode Design on Electrodermal Activity Stimulus Response Detection.
Haddad, Peter A; Servati, Amir; Soltanian, Saeid; Ko, Frank; Servati, Peyman
2017-12-01
The focus of this research is to evaluate the effects of design parameters including surface area, distance between and geometry of dry flexible electrodes on electrodermal activity (EDA) stimulus response detection. EDA is a result of the autonomic nervous system being stimulated, which causes sweat and changes the electrical characteristics of the skin. Standard silver/silver chloride (Ag/AgCl) EDA electrodes are rigid and lack conformability in contact with skin. In this study, flexible dry Ag/AgCl EDA electrodes were fabricated on a compliant substrate, used to monitor EDA stimulus responses and compared to results simultaneously collected by rigid dry Ag/AgCl electrodes. A repeatable fabrication process for flexible Ag/AgCl electrodes has been established. Surface area, distance between and geometry of electrodes are shown to affect the detectability of the EDA response and the minimum number of sweat glands to be covered by the electrodes has been estimated at 140, or more, in order to maintain functionality. The optimal flexible EDA electrode is a serpentine design with a 0.15 cm 2 surface area and a 0.20 cm distance with an average Pearson correlation coefficient of . Fabrication of flexible electrodes is described and an understanding of the effects of electrode designs on the EDA stimulus response detection has been established and is potentially related to the coverage of sweat glands. This work presents a novel systematic approach to understand the effects of electrode designs on monitoring EDA which is of importance for the design of wearable EDA monitoring devices.
Use of a Differential Observing Response to Expand Restricted Stimulus Control
Walpole, Carrie Wallace; Roscoe, Eileen M.; Dube, William V.
2007-01-01
This study extends previous work on the use of differential observing responses (DOR) to remediate atypically restricted stimulus control. A participant with autism had high matching-to-sample accuracy scores with printed words that had no letters in common (e.g., "cat," "lid," "bug") but poor accuracy with words that had two letters in common…
"Shovel-Ready" Data: The Stimulus Package and State Longitudinal Data Systems
Ewell, Peter T.
2009-01-01
The American Reinvestment and Recovery Act, commonly referred to simply as "the stimulus package," is poised to pump over $100 billion into U.S. public education in the next few years. This allocation reflects the Obama administration's new commitment to education as a public good, which is embodied in President Obama's ambitious goal of…
Low Lifetime Stress Exposure Is Associated with Reduced Stimulus-Response Memory
Goldfarb, Elizabeth V.; Shields, Grant S.; Daw, Nathaniel D.; Slavich, George M.; Phelps, Elizabeth A.
2017-01-01
Exposure to stress throughout life can cumulatively influence later health, even among young adults. The negative effects of high cumulative stress exposure are well-known, and a shift from episodic to stimulus-response memory has been proposed to underlie forms of psychopathology that are related to high lifetime stress. At the other extreme,…
Zeelenberg, René; Pecher, Diane
2015-03-01
Counterbalanced designs are frequently used in the behavioral sciences. Studies often counterbalance either the order in which conditions are presented in the experiment or the assignment of stimulus materials to conditions. Occasionally, researchers need to simultaneously counterbalance both condition order and stimulus assignment to conditions. Lewis (1989; Behavior Research Methods, Instruments, & Computers 25:414-415, 1993) presented a method for constructing Latin squares that fulfill these requirements. The resulting Latin squares counterbalance immediate sequential effects, but not remote sequential effects. Here, we present a new method for generating Latin squares that simultaneously counterbalance both immediate and remote sequential effects and assignment of stimuli to conditions. An Appendix is provided to facilitate implementation of these Latin square designs.
Wasserman, Edward A.; And Others
1975-01-01
The present series of experiments attempted to analyze more fully the contributions of stimulus-reinforcer and response-reinforcer relations to autoshaping within a single conditioning situation. (Author)
Diamantis, Dimitrios A; Ramesova, Sarka; Chatzigiannis, Christos M; Degano, Ilaria; Gerogianni, Paraskevi S; Karadima, Constantina; Perikleous, Sonia; Rekkas, Dimitrios; Gerothanassis, Ioannis P; Galaris, Dimitrios; Mavromoustakos, Thomas; Valsami, Georgia; Sokolova, Romana; Tzakos, Andreas G
2018-06-07
Flavonoids possess a rich polypharmacological profile and their biological role is linked to their oxidation state protecting DNA from oxidative stress damage. However, their bioavailability is hampered due to their poor aqueous solubility. This can be surpassed through encapsulation to supramolecular carriers as cyclodextrin (CD). A quercetin- 2HP-β-CD complex has been formerly reported by us. However, once the flavonoid is in its 2HP-β-CD encapsulated state its oxidation potential, its decomplexation mechanism, its potential to protect DNA damage from oxidative stress remained elusive. To unveil this, an array of biophysical techniques was used. The quercetin-2HP-β-CD complex was evaluated through solubility and dissolution experiments, electrochemical and spectroelectrochemical studies (Cyclic Voltammetry) UV-Vis spectroscopy, HPLC-ESI-MS/MS and HPLC-DAD, fluorescence spectroscopy, NMR Spectroscopy, theoretical calculations (density functional theory (DFT)) and biological evaluation of the protection offered against H 2 O 2 -induced DNA damage. Encapsulation of quercetin inside the supramolecule's cavity enhanced its solubility and oxidation profile is retained in its encapsulated state. Although the protective ability of the quercetin-2HP-β-CD complex against H 2 O 2 was diminished, iron serves as a chemical stimulus to dissociate the complex and release quercetin. We found that in a quercetin-2HP-β-CD inclusion complex quercetin retains its oxidation profile similarly to its native state, while iron can operate as a chemical stimulus to release quercetin from its host cavity. The oxidation profile of a natural product once it is encapsulated in a supramolecular cyclodextrin carrier as also it was discovered that decomplexation can be triggered by a chemical stimulus. Copyright © 2018. Published by Elsevier B.V.
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Anatole Nöstl
Full Text Available Participants were requested to respond to a sequence of visual targets while listening to a well-known lullaby. One of the notes in the lullaby was occasionally exchanged with a pattern deviant. Experiment 1 found that deviants capture attention as a function of the pitch difference between the deviant and the replaced/expected tone. However, when the pitch difference between the expected tone and the deviant tone is held constant, a violation to the direction-of-pitch change across tones can also capture attention (Experiment 2. Moreover, in more complex auditory environments, wherein it is difficult to build a coherent neural model of the sound environment from which expectations are formed, deviations can capture attention but it appears to matter less whether this is a violation from a specific stimulus or a violation of the current direction-of-change (Experiment 3. The results support the expectation violation account of auditory distraction and suggest that there are at least two different expectations that can be violated: One appears to be bound to a specific stimulus and the other would seem to be bound to a more global cross-stimulus rule such as the direction-of-change based on a sequence of preceding sound events. Factors like base-rate probability of tones within the sound environment might become the driving mechanism of attentional capture--rather than violated expectations--in complex sound environments.
Menz, Hylton B; Lord, Stephen R; Fitzpatrick, Richard C
2006-10-02
The purpose of this study was to determine whether the application of passive tactile cues to the lower limb could improve postural stability in healthy young controls, older people and people with diabetic peripheral neuropathy. Antero-posterior sway was measured with eyes open and closed in 10 healthy young subjects (mean age 27 years, 5 male, 5 female), 10 older subjects without diabetic peripheral neuropathy (mean age 88 years, 2 male, 8 female) and 10 subjects with diabetic peripheral neuropathy (mean age 65 years, 6 male, 4 female) while a small piece of Velcro attached to a flexible mount was applied to three different sites on the leg (ankle, calf, and knee). Across all conditions, the mean sway of the neuropathic subjects was 93% greater than for the young subjects and 11% more than the older subjects. On average, subjects swayed 10% more with the eyes closed than with the eyes open. Each stimulus reduced sway, but the effect increased approximately in proportion to the height of the stimulus above the ankles (ankle 7.6%, calf 13.5%, knee 20.1% reduction compared to the no stimulus condition). This experiment demonstrates that a passive stimulus applied to the skin of the leg, which provides sensory information about body movement, significantly reduces body sway during standing. This applies to older subjects and subjects with peripheral neuropathy as well as healthy young subjects. These results have implications for novel approaches for improving stability in people with peripheral sensory loss.
Additive and Interactive Effects of Stimulus Degradation: No Challenge for CDP+
Ziegler, Johannes C.; Perry, Conrad; Zorzi, Marco
2009-01-01
S. O'Malley and D. Besner (2008) showed that additive effects of stimulus degradation and word frequency in reading aloud occur in the presence of nonwords but not in pure word lists. They argued that this dissociation presents a major challenge to interactive computational models of reading aloud and claimed that no currently implemented model is…
Stimulus-Driven Attentional Capture by a Static Discontinuity between Perceptual Groups
Burnham, Bryan R.; Neely, James H.; Naginsky, Yelena; Thomas, Matthew
2010-01-01
After C. L. Folk, R. W. Remington, and J. C. Johnston (1992) proposed their contingent-orienting hypothesis, there has been an ongoing debate over whether purely stimulus-driven attentional capture can occur for visual events that are salient by virtue of a distinctive static property (as opposed to a dynamic property such as abrupt onset). The…
Crisis in LAC : Infrastructure Investment, Employment and the Expectations of Stimulus
Schwartz, Jordan; Andres, Luis; Dragoiu, Georgeta
2009-01-01
Infrastructure investment is a central part of the stimulus plans of the Latin America and the Caribbean (LAC) region as it confronts the growing financial crisis. This paper estimates the potential effects on direct, indirect, and induced employment for different types of infrastructure projects with LAC-specific variables. The analysis finds that the direct and indirect short-term employ...
Khan, Junad; Korczeniewska, Olga; Benoliel, Rafael; Kalladka, Mythili; Eliav, Eli; Nasri-Heir, Cibelle
2018-04-13
The aim of this study was to investigate intraoral temporal summation (TS) and conditioned pain modulation (CPM) and compare the outcome with TS and CPM induced in the forearm. In addition, we aimed to study the effect of age and gender on intraoral and forearm TS and CPM. Mechanical stimulation was induced with # 5.46 von Frey filament applying 26 grams of force. A single stimulus, followed by a train of 30 successive stimuli, was applied intraorally and to the dominant forearm. CPM was assessed with the TS test as the painful stimulus and with immersion of the nondominant hand in a hot water bath as the conditioning stimulus. Gender was significantly associated with TS but not with CPM measures. Females had significantly lower mean TS measured in the face and in the dominant forearm compared with males. Age was significantly associated with CPM, but not with TS measures. In both sites examined, older patients had significantly lower mean CPM compared with younger patients. Mechanical TM elicited in the oral cavity can be used as test stimulus for CPM testing. Intraoral modulation, both TS and CPM, has an extent similar to that of the standard cutaneous extremity. TS was lower in females, and CPM was reduced with age. Copyright © 2018 Elsevier Inc. All rights reserved.
Locus of Control, Self-esteem, Stimulus Appraisal, and Depressive Symptoms in Children
Moyal, Barbara R.
1977-01-01
Variables of self-esteem, locus of control, stimulus appraisal, and depressive symptoms, which are related to depression in adults, were investigated in a sample of nonreferred Grade 5 and Grade 6 children. Grade and sex effects were not significant. All other intervariable correlations were significant. (Author)
Giard, M H; Lavikahen, J; Reinikainen, K; Perrin, F; Bertrand, O; Pernier, J; Näätänen, R
1995-01-01
Abstract The present study analyzed the neural correlates of acoustic stimulus representation in echoic sensory memory. The neural traces of auditory sensory memory were indirectly studied by using the mismatch negativity (MMN), an event-related potential component elicited by a change in a repetitive sound. The MMN is assumed to reflect change detection in a comparison process between the sensory input from a deviant stimulus and the neural representation of repetitive stimuli in echoic memory. The scalp topographies of the MMNs elicited by pure tones deviating from standard tones by either frequency, intensity, or duration varied according to the type of stimulus deviance, indicating that the MMNs for different attributes originate, at least in part, from distinct neural populations in the auditory cortex. This result was supported by dipole-model analysis. If the MMN generator process occurs where the stimulus information is stored, these findings strongly suggest that the frequency, intensity, and duration of acoustic stimuli have a separate neural representation in sensory memory.
Smith, Douglas A; Negus, S Stevens; Poklis, Justin L; Blough, Bruce E; Banks, Matthew L
2017-09-01
Synthetic cathinones are beta-ketone amphetamine analogs that have emerged as a heterogeneous class of abused compounds that function as either monoamine transporter substrates or inhibitors. Pre-clinical drug discrimination procedures are useful for interrogating structure-activity relationships of abuse-related drug effects; however, in vivo structure-activity relationship comparisons between synthetic cathinones with different mechanisms of action are lacking. The aim of the present study was to determine whether the cocaine-like discriminative stimulus effects of the monoamine transporter inhibitor alpha-pyrrolidinovalerophenone (alpha-PVP) and the monoamine transporter substrate methcathinone were differentially sensitive to 3,4-methylenedioxy and 4-methyl substitutions. Male rhesus monkeys (n = 4) were trained to discriminate intramuscular cocaine (0.32 mg/kg) from saline in a two-key food-reinforced discrimination procedure. Potency and timecourse of cocaine-like discriminative stimulus effects were determined for (±)-alpha-PVP, (±)-methcathinone and their 3,4-methylenedioxy or 4-methyl analogs. Alpha-PVP and methcathinone produced dose- and time-dependent cocaine-like effects. A 3,4-methylenedioxy addition to either alpha-PVP or methcathinone (methylone) did not alter the potency or efficacy to produce cocaine-like effects, but did prolong the time course. A 4-methyl addition to alpha-PVP (pyrovalerone) did not alter the potency or efficacy to produce cocaine-like effects, but did prolong the time course. In contrast, addition of a 4-methyl moiety to methcathinone (4MMC; mephedrone) significantly attenuated efficacy to produce cocaine-like effects. Overall, these results suggest different structural requirements for cocaine-like discriminative stimulus effects of monoamine transporter inhibitor and substrate synthetic cathinone analogs. Given that 4MMC is more hydrophobic than MDMC, these results suggest that hydrophobicity may be an important
Face distortion aftereffects evoked by featureless first-order stimulus configurations
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Pál eVakli
2012-12-01
Full Text Available After prolonged exposure to a distorted face with expanded or contracted inner features, a subsequently presented normal face appears distorted towards the opposite direction. This phenomenon, termed as face distortion aftereffect (FDAE, is thought to occur as a result of changes in the mechanisms involved in higher order visual processing. However, the extent to which FDAE is mediated by face-specific configural processing is less known. In the present study, we investigated whether similar aftereffects can be induced by stimuli lacking all the typical characteristics of a human face except for its first-order configural properties. We found a significant FDAE after adaptation to a stimulus consisting of three white dots arranged in a triangular fashion and placed in a grey oval. FDAEs occurred also when the adapting and test stimuli differed in size or when the contrast polarity of the adaptor image was changed. However, the inversion of the adapting image as well as the reduction of its contrast abolished the aftereffect entirely. Taken together, our results suggest that higher-level visual areas, which are involved in the processing of facial configurations, mediate the FDAE. Further, while adaptation seems to be largely invariant to contrast polarity, it appears sensitive to orientation and to lower level manipulations that affect the saliency of the inner features.
Mechanism of acetylcholine receptor cluster formation induced by DC electric field.
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Hailong Luke Zhang
Full Text Available BACKGROUND: The formation of acetylcholine receptor (AChR cluster is a key event during the development of the neuromuscular junction. It is induced through the activation of muscle-specific kinase (MuSK by the heparan-sulfate proteoglycan agrin released from the motor axon. On the other hand, DC electric field, a non-neuronal stimulus, is also highly effective in causing AChRs to cluster along the cathode-facing edge of muscle cells. METHODOLOGY/PRINCIPAL FINDINGS: To understand its molecular mechanism, quantum dots (QDs were used to follow the movement of AChRs as they became clustered under the influence of electric field. From analyses of trajectories of AChR movement in the membrane, it was concluded that diffuse receptors underwent Brownian motion until they were immobilized at sites of cluster formation. This supports the diffusion-mediated trapping model in explaining AChR clustering under the influence of this stimulus. Disrupting F-actin cytoskeleton assembly and interfering with rapsyn-AChR interaction suppressed this phenomenon, suggesting that these are integral components of the trapping mechanism induced by the electric field. Consistent with the idea that signaling pathways are activated by this stimulus, the localization of tyrosine-phosphorylated forms of AChR β-subunit and Src was observed at cathodal AChR clusters. Furthermore, disrupting MuSK activity through the expression of a kinase-dead form of this enzyme abolished electric field-induced AChR clustering. CONCLUSIONS: These results suggest that DC electric field as a physical stimulus elicits molecular reactions in muscle cells in the form of cathodal MuSK activation in a ligand-free manner to trigger a signaling pathway that leads to cytoskeletal assembly and AChR clustering.
Mainsah, B O; Reeves, G; Collins, L M; Throckmorton, C S
2017-08-01
The role of a brain-computer interface (BCI) is to discern a user's intended message or action by extracting and decoding relevant information from brain signals. Stimulus-driven BCIs, such as the P300 speller, rely on detecting event-related potentials (ERPs) in response to a user attending to relevant or target stimulus events. However, this process is error-prone because the ERPs are embedded in noisy electroencephalography (EEG) data, representing a fundamental problem in communication of the uncertainty in the information that is received during noisy transmission. A BCI can be modeled as a noisy communication system and an information-theoretic approach can be exploited to design a stimulus presentation paradigm to maximize the information content that is presented to the user. However, previous methods that focused on designing error-correcting codes failed to provide significant performance improvements due to underestimating the effects of psycho-physiological factors on the P300 ERP elicitation process and a limited ability to predict online performance with their proposed methods. Maximizing the information rate favors the selection of stimulus presentation patterns with increased target presentation frequency, which exacerbates refractory effects and negatively impacts performance within the context of an oddball paradigm. An information-theoretic approach that seeks to understand the fundamental trade-off between information rate and reliability is desirable. We developed a performance-based paradigm (PBP) by tuning specific parameters of the stimulus presentation paradigm to maximize performance while minimizing refractory effects. We used a probabilistic-based performance prediction method as an evaluation criterion to select a final configuration of the PBP. With our PBP, we demonstrate statistically significant improvements in online performance, both in accuracy and spelling rate, compared to the conventional row-column paradigm. By accounting for
Regular Exposure to Cowbells Affects the Behavioral Reactivity to a Noise Stimulus in Dairy Cows
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Julia Johns
2017-09-01
Full Text Available In alpine regions, cows are often equipped with bells during pasture season to ensure that farmers can locate them. Constant exposure to the chime of a bell may affect cows’ acoustic perception in general. The aim of this study is to test whether routine bell exposure affects the reactivity to a noise stimulus and might be associated with hearing impairment in cows. For the assessment, behavioral and cardiac indicators were used as indirect measures of hearing capacity. Cows that were either used to wearing a bell or not were exposed to a playback of low and high amplitude (=varying loudness. In addition, we tested whether wearing earplugs, mimicking hearing impairment, reduced the cows’ reactivity toward the playback. On 24 farms, half of them routinely using cowbells, 96 Brown Swiss cows were tested in a 2 × 2 factorial cross-over design (65 or 85 dB, without or with earplugs in a balanced order. The effects of bell experience, amplitude, and earplugs on the latency to the first behavioral and cardiac response to a 5-s playback were analyzed using linear mixed-effects models, considering dependencies within the data set. Cows reacted faster without earplugs and when they were exposed to 85 dB compared with 65 dB. The proportion of cows leaving the feeding rack after onset of the playback was reduced by bell experience and earplugs and was increased when exposed to 85 dB compared with 65 dB. Exposure without earplugs to 85 dB but not to 65 dB increased heart rate. Heart rate and heart rate variability indicated increased sympathetic activation during the exposure to 85 dB compared with 65 dB. In general, behavioral and cardiac indicators did not indicate severe hearing impairment due to routine bell exposure. The 85-dB stimulus increased arousal and avoidance compared with the 65-dB stimulus, with bell experience and earplugs leading to a general decrease in avoidance of the stimulus. This may reflect an altered
The Role of Common Motor Responses in Stimulus Categorization by Preschool Children
Mahoney, Amanda M; Miguel, Caio F; Ahearn, William H; Bell, Julianne
2011-01-01
The purpose of this study was to assess the role of common motor responses as the “speaker” behavior on stimulus class formation, and the emergence of functional classes. Experiment 1 examined whether training one motor response to a set of three stimuli and a second motor response to another set of three stimuli would result in correct category-sort responses for 5 typically developing preschool children. Three of the children passed the categorization tests. Experiment 2 examined whether the classes formed in Experiment 1 were functional classes, and whether participants who did not pass categorization tests in Experiment 1 would do so following common vocal tact training. The 2 participants who failed categorization tests in Experiment 1 passed these tests in Experiment 2, although none of the participants passed the tests for functional classes. The results of the current study did not unequivocally support the naming hypothesis. Future research should therefore evaluate other possible sources of control that aid in stimulus categorization. PMID:21541124
Rehfeldt, Ruth Anne
2011-01-01
Every article on stimulus equivalence or derived stimulus relations published in the Journal of Applied Behavior Analysis was evaluated in terms of characteristics that are relevant to the development of applied technologies: the type of participants, settings, procedure (automated vs. tabletop), stimuli, and stimulus sensory modality; types of relations targeted and emergent skills demonstrated by participants; and presence versus absence of evaluation of generalization and maintenance. In most respects, published reports suggested the possibility of applied technologies but left the difficult work of technology development to future investigations, suggestions for which are provided.
Cain, Sean W; Yoon, Jeena; Shrestha, Tenjin C; Ralph, Martin R
2014-10-01
Circadian rhythmic expression of conditioned place avoidance (CPA) was produced in Syrian hamsters homozygous for the circadian short period mutation, tau. In constant dim red light neither the 20 h endogenous period, nor a 20 h place conditioning schedule eliminated the 24 h modulation of CPA behavior described previously for wild type (wt) hamsters and other species. Tau mutants exhibited a 20 h rhythm superimposed on the 24 h modulation. The 20 h component was removed selectively with lesions of the suprachiasmatic nucleus. Wt animals conditioned on a 20 h schedule did not produce a 20 h rhythm, but still expressed the 24 h modulation. The results show that the context entrainable oscillator (CEO) underlying memory for the timing of an unconditioned stimulus, retains a period of about 24 h regardless of clock gene background (tau mutation) and/or the conditioning schedule (24 vs 20 h). Therefore the CEO responsible for time memory is distinct from the biological clock controlling activity; the underlying circadian molecular mechanisms may differ from the ubiquitous transcription-translation feedback oscillator; and time memory itself is not classically conditioned. Copyright © 2014 Elsevier Inc. All rights reserved.
Heuer, Sabine; Ivanova, Maria V.; Hallowell, Brooke
2017-01-01
Purpose: Language comprehension in people with aphasia (PWA) is frequently evaluated using multiple-choice displays: PWA are asked to choose the image that best corresponds to the verbal stimulus in a display. When a nontarget image is selected, comprehension failure is assumed. However, stimulus-driven factors unrelated to linguistic…
Does bimodal stimulus presentation increase ERP components usable in BCIs?
Thurlings, Marieke E.; Brouwer, Anne-Marie; Van Erp, Jan B. F.; Blankertz, Benjamin; Werkhoven, Peter J.
2012-08-01
Event-related potential (ERP)-based brain-computer interfaces (BCIs) employ differences in brain responses to attended and ignored stimuli. Typically, visual stimuli are used. Tactile stimuli have recently been suggested as a gaze-independent alternative. Bimodal stimuli could evoke additional brain activity due to multisensory integration which may be of use in BCIs. We investigated the effect of visual-tactile stimulus presentation on the chain of ERP components, BCI performance (classification accuracies and bitrates) and participants’ task performance (counting of targets). Ten participants were instructed to navigate a visual display by attending (spatially) to targets in sequences of either visual, tactile or visual-tactile stimuli. We observe that attending to visual-tactile (compared to either visual or tactile) stimuli results in an enhanced early ERP component (N1). This bimodal N1 may enhance BCI performance, as suggested by a nonsignificant positive trend in offline classification accuracies. A late ERP component (P300) is reduced when attending to visual-tactile compared to visual stimuli, which is consistent with the nonsignificant negative trend of participants’ task performance. We discuss these findings in the light of affected spatial attention at high-level compared to low-level stimulus processing. Furthermore, we evaluate bimodal BCIs from a practical perspective and for future applications.
Marshall, T.R.; Boer, Sebastiaan den; Cools, R.; Jensen, O.; Fallon, S.J.; Zumer, J.
2018-01-01
Selective attention is reflected neurally in changes in the power of posterior neural oscillations in the alpha (8–12 Hz) and gamma (40–100 Hz) bands. Although a neural mechanism that allows relevant information to be selectively processed has its advantages, it may lead to lucrative or dangerous
Oscillatory Hierarchy Controlling Cortical Excitability and Stimulus Integration
Shah, A. S.; Lakatos, P.; McGinnis, T.; O'Connell, N.; Mills, A.; Knuth, K. H.; Chen, C.; Karmos, G.; Schroeder, C. E.
2004-01-01
Cortical gamma band oscillations have been recorded in sensory cortices of cats and monkeys, and are thought to aid in perceptual binding. Gamma activity has also been recorded in the rat hippocampus and entorhinal cortex, where it has been shown, that field gamma power is modulated at theta frequency. Since the power of gamma activity in the sensory cortices is not constant (gamma-bursts). we decided to examine the relationship between gamma power and the phase of low frequency oscillation in the auditory cortex of the awake macaque. Macaque monkeys were surgically prepared for chronic awake electrophysiological recording. During the time of the experiments. linear array multielectrodes were inserted in area AI to obtain laminar current source density (CSD) and multiunit activity profiles. Instantaneous theta and gamma power and phase was extracted by applying the Morlet wavelet transformation to the CSD. Gamma power was averaged for every 1 degree of low frequency oscillations to calculate power-phase relation. Both gamma and theta-delta power are largest in the supragranular layers. Power modulation of gamma activity is phase locked to spontaneous, as well as stimulus-related local theta and delta field oscillations. Our analysis also revealed that the power of theta oscillations is always largest at a certain phase of delta oscillation. Auditory stimuli produce evoked responses in the theta band (Le., there is pre- to post-stimulus addition of theta power), but there is also indication that stimuli may cause partial phase re-setting of spontaneous delta (and thus also theta and gamma) oscillations. We also show that spontaneous oscillations might play a role in the processing of incoming sensory signals by 'preparing' the cortex.
Nonassociative learning as gated neural integrator and differentiator in stimulus-response pathways
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Young Daniel L
2006-08-01
Full Text Available Abstract Nonassociative learning is a basic neuroadaptive behavior exhibited across animal phyla and sensory modalities but its role in brain intelligence is unclear. Current literature on habituation and sensitization, the classic "dual process" of nonassociative learning, gives highly incongruous accounts between varying experimental paradigms. Here we propose a general theory of nonassociative learning featuring four base modes: habituation/primary sensitization in primary stimulus-response pathways, and desensitization/secondary sensitization in secondary stimulus-response pathways. Primary and secondary modes of nonassociative learning are distinguished by corresponding activity-dependent recall, or nonassociative gating, of neurotransmission memory. From the perspective of brain computation, nonassociative learning is a form of integral-differential calculus whereas nonassociative gating is a form of Boolean logic operator – both dynamically transforming the stimulus-response relationship. From the perspective of sensory integration, nonassociative gating provides temporal filtering whereas nonassociative learning affords low-pass, high-pass or band-pass/band-stop frequency filtering – effectively creating an intelligent sensory firewall that screens all stimuli for attention and resultant internal model adaptation and reaction. This unified framework ties together many salient characteristics of nonassociative learning and nonassociative gating and suggests a common kernel that correlates with a wide variety of sensorimotor integration behaviors such as central resetting and self-organization of sensory inputs, fail-safe sensorimotor compensation, integral-differential and gated modulation of sensorimotor feedbacks, alarm reaction, novelty detection and selective attention, as well as a variety of mental and neurological disorders such as sensorimotor instability, attention deficit hyperactivity, sensory defensiveness, autism
The iso-response method: measuring neuronal stimulus integration with closed-loop experiments
Gollisch, Tim; Herz, Andreas V. M.
2012-01-01
Throughout the nervous system, neurons integrate high-dimensional input streams and transform them into an output of their own. This integration of incoming signals involves filtering processes and complex non-linear operations. The shapes of these filters and non-linearities determine the computational features of single neurons and their functional roles within larger networks. A detailed characterization of signal integration is thus a central ingredient to understanding information processing in neural circuits. Conventional methods for measuring single-neuron response properties, such as reverse correlation, however, are often limited by the implicit assumption that stimulus integration occurs in a linear fashion. Here, we review a conceptual and experimental alternative that is based on exploring the space of those sensory stimuli that result in the same neural output. As demonstrated by recent results in the auditory and visual system, such iso-response stimuli can be used to identify the non-linearities relevant for stimulus integration, disentangle consecutive neural processing steps, and determine their characteristics with unprecedented precision. Automated closed-loop experiments are crucial for this advance, allowing rapid search strategies for identifying iso-response stimuli during experiments. Prime targets for the method are feed-forward neural signaling chains in sensory systems, but the method has also been successfully applied to feedback systems. Depending on the specific question, “iso-response” may refer to a predefined firing rate, single-spike probability, first-spike latency, or other output measures. Examples from different studies show that substantial progress in understanding neural dynamics and coding can be achieved once rapid online data analysis and stimulus generation, adaptive sampling, and computational modeling are tightly integrated into experiments. PMID:23267315
Stimulus homogeneity enhances implicit learning: evidence from contextual cueing.
Feldmann-Wüstefeld, Tobias; Schubö, Anna
2014-04-01
Visual search for a target object is faster if the target is embedded in a repeatedly presented invariant configuration of distractors ('contextual cueing'). It has also been shown that the homogeneity of a context affects the efficiency of visual search: targets receive prioritized processing when presented in a homogeneous context compared to a heterogeneous context, presumably due to grouping processes at early stages of visual processing. The present study investigated in three Experiments whether context homogeneity also affects contextual cueing. In Experiment 1, context homogeneity varied on three levels of the task-relevant dimension (orientation) and contextual cueing was most pronounced for context configurations with high orientation homogeneity. When context homogeneity varied on three levels of the task-irrelevant dimension (color) and orientation homogeneity was fixed, no modulation of contextual cueing was observed: high orientation homogeneity led to large contextual cueing effects (Experiment 2) and low orientation homogeneity led to low contextual cueing effects (Experiment 3), irrespective of color homogeneity. Enhanced contextual cueing for homogeneous context configurations suggest that grouping processes do not only affect visual search but also implicit learning. We conclude that memory representation of context configurations are more easily acquired when context configurations can be processed as larger, grouped perceptual units. However, this form of implicit perceptual learning is only improved by stimulus homogeneity when stimulus homogeneity facilitates grouping processes on a dimension that is currently relevant in the task. Copyright © 2014 Elsevier B.V. All rights reserved.
Metabolic cost of neuronal information in an empirical stimulus-response model
Czech Academy of Sciences Publication Activity Database
Košťál, Lubomír; Lánský, Petr; McDonnell, M.D.
2013-01-01
Roč. 107, č. 3 (2013), s. 355-365 ISSN 0340-1200 R&D Projects: GA ČR(CZ) GBP304/12/G069; GA ČR(CZ) GAP103/11/0282; GA ČR(CZ) GPP103/12/P558 Institutional support: RVO:67985823 Keywords : information capacity * metabolic cost * stimulus-response curve Subject RIV: FH - Neurology Impact factor: 1.933, year: 2013
Donohue, Sarah E; Todisco, Alexandra E; Woldorff, Marty G
2013-04-01
Neuroimaging work on multisensory conflict suggests that the relevant modality receives enhanced processing in the face of incongruency. However, the degree of stimulus processing in the irrelevant modality and the temporal cascade of the attentional modulations in either the relevant or irrelevant modalities are unknown. Here, we employed an audiovisual conflict paradigm with a sensory probe in the task-irrelevant modality (vision) to gauge the attentional allocation to that modality. ERPs were recorded as participants attended to and discriminated spoken auditory letters while ignoring simultaneous bilateral visual letter stimuli that were either fully congruent, fully incongruent, or partially incongruent (one side incongruent, one congruent) with the auditory stimulation. Half of the audiovisual letter stimuli were followed 500-700 msec later by a bilateral visual probe stimulus. As expected, ERPs to the audiovisual stimuli showed an incongruency ERP effect (fully incongruent versus fully congruent) of an enhanced, centrally distributed, negative-polarity wave starting ∼250 msec. More critically here, the sensory ERP components to the visual probes were larger when they followed fully incongruent versus fully congruent multisensory stimuli, with these enhancements greatest on fully incongruent trials with the slowest RTs. In addition, on the slowest-response partially incongruent trials, the P2 sensory component to the visual probes was larger contralateral to the preceding incongruent visual stimulus. These data suggest that, in response to conflicting multisensory stimulus input, the initial cognitive effect is a capture of attention by the incongruent irrelevant-modality input, pulling neural processing resources toward that modality, resulting in rapid enhancement, rather than rapid suppression, of that input.
Graewe, Britta; De Weerd, Peter; Farivar, Reza; Castelo-Branco, Miguel
2012-01-01
Many studies have linked the processing of different object categories to specific event-related potentials (ERPs) such as the face-specific N170. Despite reports showing that object-related ERPs are influenced by visual stimulus features, there is consensus that these components primarily reflect categorical aspects of the stimuli. Here, we re-investigated this idea by systematically measuring the effects of visual feature manipulations on ERP responses elicited by both structure-from-motion (SFM)-defined and luminance-defined object stimuli. SFM objects elicited a novel component at 200–250 ms (N250) over parietal and posterior temporal sites. We found, however, that the N250 amplitude was unaffected by restructuring SFM stimuli into meaningless objects based on identical visual cues. This suggests that this N250 peak was not uniquely linked to categorical aspects of the objects, but is strongly determined by visual stimulus features. We provide strong support for this hypothesis by parametrically manipulating the depth range of both SFM- and luminance-defined object stimuli and showing that the N250 evoked by SFM stimuli as well as the well-known N170 to static faces were sensitive to this manipulation. Importantly, this effect could not be attributed to compromised object categorization in low depth stimuli, confirming a strong impact of visual stimulus features on object-related ERP signals. As ERP components linked with visual categorical object perception are likely determined by multiple stimulus features, this creates an interesting inverse problem when deriving specific perceptual processes from variations in ERP components. PMID:22363479
Can Collateral Behavior Account for Transitions in the Stimulus Control of Speech?
Palmer, David C.
2017-01-01
The task of extending Skinner's (1957) interpretation of verbal behavior includes accounting for the moment-to-moment changes in stimulus control as one speaks. A consideration of the behavior of the reader reminds us of the continuous evocative effect of verbal stimuli on readers, listeners, and speakers. Collateral discriminative responses to…
Arntzen, Erik; Grondahl, Terje; Eilifsen, Christoffer
2010-01-01
Previous studies comparing groups of subjects have indicated differential probabilities of stimulus equivalence outcome as a function of training structures. One-to-Many (OTM) and Many-to-One (MTO) training structures seem to produce positive outcomes on tests for stimulus equivalence more often than a Linear Series (LS) training structure does.…
From the Stimulus-Response to the Person-Context Model
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Arturo Barraza Macías
2007-07-01
Full Text Available In this manuscript, an alternative reading of the field of study of the stress is made that leads to raise the existence of two models: the Stimulus-Response and the Person-Context Models about Stress. Each one of them is presented with base in four indicators: historical antecedents, postulates, development and characteristics. In the end a critical valuation is made that the author leads to recognize in the Person-Surroundings Research Program of Stress, and in its tendency to the modeling, the route of development of the field of study of stress.
McNeilly, Alison D; Gallagher, Jennifer R; Huang, Jeffrey T-J; Ashford, Michael L J; McCrimmon, Rory J
2017-06-01
Hypoglycemia is a major adverse effect of insulin therapy for people with type 1 diabetes (T1D). Profound defects in the normal counterregulatory response to hypoglycemia explain the frequency of hypoglycemia occurrence in T1D. Defective counterregulation results to a large extent from prior exposure to hypoglycemia per se, leading to a condition called impaired awareness of hypoglycemia (IAH), the cause of which is unknown. In the current study, we investigate the hypothesis that IAH develops through a special type of adaptive memory referred to as habituation. To test this hypothesis, we used a novel intense stimulus (high-intensity exercise) to demonstrate two classic features of a habituated response, namely dishabituation and response recovery. We demonstrate that after recurrent hypoglycemia the introduction of a novel dishabituating stimulus (a single burst of high-intensity exercise) in male Sprague-Dawley rats restores the defective hypoglycemia counterregulatory response. In addition, the rats showed an enhanced response to the novel stimulus (response recovery). We make the further observation using proteomic analysis of hypothalamic extracts that high-intensity exercise in recurrently hypoglycemic rats increases levels of a number of proteins linked with brain-derived neurotrophic factor signaling. These findings may lead to novel therapeutic approaches for individuals with T1D and IAH. © 2017 by the American Diabetes Association.
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László Szécsi
2017-12-01
Full Text Available Light stimulation with precise and complex spatial and temporal modulation is demanded by a series of research fields like visual neuroscience, optogenetics, ophthalmology, and visual psychophysics. We developed a user-friendly and flexible stimulus generating framework (GEARS GPU-based Eye And Retina Stimulation Software, which offers access to GPU computing power, and allows interactive modification of stimulus parameters during experiments. Furthermore, it has built-in support for driving external equipment, as well as for synchronization tasks, via USB ports. The use of GEARS does not require elaborate programming skills. The necessary scripting is visually aided by an intuitive interface, while the details of the underlying software and hardware components remain hidden. Internally, the software is a C++/Python hybrid using OpenGL graphics. Computations are performed on the GPU, and are defined in the GLSL shading language. However, all GPU settings, including the GPU shader programs, are automatically generated by GEARS. This is configured through a method encountered in game programming, which allows high flexibility: stimuli are straightforwardly composed using a broad library of basic components. Stimulus rendering is implemented solely in C++, therefore intermediary libraries for interfacing could be omitted. This enables the program to perform computationally demanding tasks like en-masse random number generation or real-time image processing by local and global operations.
Szécsi, László; Kacsó, Ágota; Zeck, Günther; Hantz, Péter
2017-01-01
Light stimulation with precise and complex spatial and temporal modulation is demanded by a series of research fields like visual neuroscience, optogenetics, ophthalmology, and visual psychophysics. We developed a user-friendly and flexible stimulus generating framework (GEARS GPU-based Eye And Retina Stimulation Software), which offers access to GPU computing power, and allows interactive modification of stimulus parameters during experiments. Furthermore, it has built-in support for driving external equipment, as well as for synchronization tasks, via USB ports. The use of GEARS does not require elaborate programming skills. The necessary scripting is visually aided by an intuitive interface, while the details of the underlying software and hardware components remain hidden. Internally, the software is a C++/Python hybrid using OpenGL graphics. Computations are performed on the GPU, and are defined in the GLSL shading language. However, all GPU settings, including the GPU shader programs, are automatically generated by GEARS. This is configured through a method encountered in game programming, which allows high flexibility: stimuli are straightforwardly composed using a broad library of basic components. Stimulus rendering is implemented solely in C++, therefore intermediary libraries for interfacing could be omitted. This enables the program to perform computationally demanding tasks like en-masse random number generation or real-time image processing by local and global operations.
ANALYSIS OF CONSUMPTION EXPENDITURE IN ROMANIA, PERIOD 2009-2015
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BÂLDAN FLORENTINA CRISTINA
2017-06-01
Full Text Available The paper „Analysis of consumption expenditure in Romania, period 2009-2015” is highlighting a very important phenomenon for the Romanian economy, consumption. The financial and economic crisis determined a change in the income repartition for the basic products and services. The most influent stimulus at which the Romanian consumers are deciding a product acquisition is the price, therefore they were migrating to product segments with low prices, the quality of life being on a decreasing trend. The level of alimentary products consumption depends in a big extent on the macroeconomic policies, that through numerous leverages is influencing the population consumption behavior. From these leverages we may document the income policy, loan policy, monetary and exchange rate policies, social assistance policy, etc.
Cecere, Roberto; Gross, Joachim; Thut, Gregor
2016-06-01
The ability to integrate auditory and visual information is critical for effective perception and interaction with the environment, and is thought to be abnormal in some clinical populations. Several studies have investigated the time window over which audiovisual events are integrated, also called the temporal binding window, and revealed asymmetries depending on the order of audiovisual input (i.e. the leading sense). When judging audiovisual simultaneity, the binding window appears narrower and non-malleable for auditory-leading stimulus pairs and wider and trainable for visual-leading pairs. Here we specifically examined the level of independence of binding mechanisms when auditory-before-visual vs. visual-before-auditory input is bound. Three groups of healthy participants practiced audiovisual simultaneity detection with feedback, selectively training on auditory-leading stimulus pairs (group 1), visual-leading stimulus pairs (group 2) or both (group 3). Subsequently, we tested for learning transfer (crossover) from trained stimulus pairs to non-trained pairs with opposite audiovisual input. Our data confirmed the known asymmetry in size and trainability for auditory-visual vs. visual-auditory binding windows. More importantly, practicing one type of audiovisual integration (e.g. auditory-visual) did not affect the other type (e.g. visual-auditory), even if trainable by within-condition practice. Together, these results provide crucial evidence that audiovisual temporal binding for auditory-leading vs. visual-leading stimulus pairs are independent, possibly tapping into different circuits for audiovisual integration due to engagement of different multisensory sampling mechanisms depending on leading sense. Our results have implications for informing the study of multisensory interactions in healthy participants and clinical populations with dysfunctional multisensory integration. © 2016 The Authors. European Journal of Neuroscience published by Federation
Interspike Interval Based Filtering of Directional Selective Retinal Ganglion Cells Spike Trains
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Aurel Vasile Martiniuc
2012-01-01
Full Text Available The information regarding visual stimulus is encoded in spike trains at the output of retina by retinal ganglion cells (RGCs. Among these, the directional selective cells (DSRGC are signaling the direction of stimulus motion. DSRGCs' spike trains show accentuated periods of short interspike intervals (ISIs framed by periods of isolated spikes. Here we use two types of visual stimulus, white noise and drifting bars, and show that short ISI spikes of DSRGCs spike trains are more often correlated to their preferred stimulus feature (that is, the direction of stimulus motion and carry more information than longer ISI spikes. Firstly, our results show that correlation between stimulus and recorded neuronal response is best at short ISI spiking activity and decrease as ISI becomes larger. We then used grating bars stimulus and found that as ISI becomes shorter the directional selectivity is better and information rates are higher. Interestingly, for the less encountered type of DSRGC, known as ON-DSRGC, short ISI distribution and information rates revealed consistent differences when compared with the other directional selective cell type, the ON-OFF DSRGC. However, these findings suggest that ISI-based temporal filtering integrates a mechanism for visual information processing at the output of retina toward higher stages within early visual system.
Improving accuracy of portion-size estimations through a stimulus equivalence paradigm.
Hausman, Nicole L; Borrero, John C; Fisher, Alyssa; Kahng, SungWoo
2014-01-01
The prevalence of obesity continues to increase in the United States (Gordon-Larsen, The, & Adair, 2010). Obesity can be attributed, in part, to overconsumption of energy-dense foods. Given that overeating plays a role in the development of obesity, interventions that teach individuals to identify and consume appropriate portion sizes are warranted. Specifically, interventions that teach individuals to estimate portion sizes correctly without the use of aids may be critical to the success of nutrition education programs. The current study evaluated the use of a stimulus equivalence paradigm to teach 9 undergraduate students to estimate portion size accurately. Results suggested that the stimulus equivalence paradigm was effective in teaching participants to make accurate portion size estimations without aids, and improved accuracy was observed in maintenance sessions that were conducted 1 week after training. Furthermore, 5 of 7 participants estimated the target portion size of novel foods during extension sessions. These data extend existing research on teaching accurate portion-size estimations and may be applicable to populations who seek treatment (e.g., overweight or obese children and adults) to teach healthier eating habits. © Society for the Experimental Analysis of Behavior.
Park, Seoung Hoon; Kim, Seonjin; Kwon, MinHyuk; Christou, Evangelos A
2016-03-01
Vision and auditory information are critical for perception and to enhance the ability of an individual to respond accurately to a stimulus. However, it is unknown whether visual and auditory information contribute differentially to identify the direction and rotational motion of the stimulus. The purpose of this study was to determine the ability of an individual to accurately predict the direction and rotational motion of the stimulus based on visual and auditory information. In this study, we recruited 9 expert table-tennis players and used table-tennis service as our experimental model. Participants watched recorded services with different levels of visual and auditory information. The goal was to anticipate the direction of the service (left or right) and the rotational motion of service (topspin, sidespin, or cut). We recorded their responses and quantified the following outcomes: (i) directional accuracy and (ii) rotational motion accuracy. The response accuracy was the accurate predictions relative to the total number of trials. The ability of the participants to predict the direction of the service accurately increased with additional visual information but not with auditory information. In contrast, the ability of the participants to predict the rotational motion of the service accurately increased with the addition of auditory information to visual information but not with additional visual information alone. In conclusion, this finding demonstrates that visual information enhances the ability of an individual to accurately predict the direction of the stimulus, whereas additional auditory information enhances the ability of an individual to accurately predict the rotational motion of stimulus.
Klein, Carina; Diaz Hernandez, Laura; Koenig, Thomas; Kottlow, Mara; Elmer, Stefan; Jäncke, Lutz
2016-01-01
Previous work highlighted the possibility that musical training has an influence on cognitive functioning. The suggested reason for this influence is the strong recruitment of attention, planning, and working memory functions during playing a musical instrument. The purpose of the present work was twofold, namely to evaluate the general relationship between pre-stimulus electrophysiological activity and cognition, and more specifically the influence of musical expertise on working memory functions. With this purpose in mind, we used covariance mapping analyses to evaluate whether pre-stimulus electroencephalographic activity is predictive for reaction time during a visual working memory task (Sternberg paradigm) in musicians and non-musicians. In line with our hypothesis, we replicated previous findings pointing to a general predictive value of pre-stimulus activity for working memory performance. Most importantly, we also provide first evidence for an influence of musical expertise on working memory performance that could distinctively be predicted by pre-stimulus spectral power. Our results open novel perspectives for better comprehending the vast influences of musical expertise on cognition.
Brain mechanisms of flavor learning
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Takashi eYamamoto
2011-09-01
Full Text Available Once the flavor of the ingested food (conditioned stimulus, CS is associated with a preferable (e.g., good taste or nutritive satisfaction or aversive (e.g., malaise with displeasure signal (unconditioned stimulus, US, animals react to its subsequent exposure by increasing or decreasing ingestion to the food. These two types of association learning (preference learning vs. aversion learning are known as classical conditioned reactions which are basic learning and memory phenomena, leading selection of food and proper food intake. Since the perception of flavor is generated by interaction of taste and odor during food intake, taste and/or odor are mainly associated with bodily signals in the flavor learning. After briefly reviewing flavor learning in general, brain mechanisms of conditioned taste aversion is described in more detail. The CS-US association leading to long-term potentiation in the amygdala, especially in its basolateral nucleus, is the basis of establishment of conditioned taste aversion. The novelty of the CS detected by the cortical gustatory area may be supportive in CS-US association. After the association, CS input is conveyed through the amygdala to different brain regions including the hippocampus for contextual fear formation, to the supramammilary and thalamic paraventricular nuclei for stressful anxiety or memory dependent fearful or stressful emotion, to the reward system to induce aversive expression to the CS, or hedonic shift from positive to negative, and to the CS-responsive neurons in the gustatory system to enhance the responsiveness to facilitate to detect the harmful stimulus.
Brain mechanisms of flavor learning.
Yamamoto, Takashi; Ueji, Kayoko
2011-01-01
Once the flavor of the ingested food (conditioned stimulus, CS) is associated with a preferable (e.g., good taste or nutritive satisfaction) or aversive (e.g., malaise with displeasure) signal (unconditioned stimulus, US), animals react to its subsequent exposure by increasing or decreasing ingestion to the food. These two types of association learning (preference learning vs. aversion learning) are known as classical conditioned reactions which are basic learning and memory phenomena, leading selection of food and proper food intake. Since the perception of flavor is generated by interaction of taste and odor during food intake, taste and/or odor are mainly associated with bodily signals in the flavor learning. After briefly reviewing flavor learning in general, brain mechanisms of conditioned taste aversion is described in more detail. The CS-US association leading to long-term potentiation in the amygdala, especially in its basolateral nucleus, is the basis of establishment of conditioned taste aversion. The novelty of the CS detected by the cortical gustatory area may be supportive in CS-US association. After the association, CS input is conveyed through the amygdala to different brain regions including the hippocampus for contextual fear formation, to the supramammillary and thalamic paraventricular nuclei for stressful anxiety or memory dependent fearful or stressful emotion, to the reward system to induce aversive expression to the CS, or hedonic shift from positive to negative, and to the CS-responsive neurons in the gustatory system to enhance the responsiveness to facilitate to detect the harmful stimulus.
Inglis, W L; Olmstead, M C; Robbins, T W
2000-04-01
The role of the pedunculopontine tegmental nucleus (PPTg) in stimulus-reward learning was assessed by testing the effects of PPTg lesions on performance in visual autoshaping and conditioned reinforcement (CRf) paradigms. Rats with PPTg lesions were unable to learn an association between a conditioned stimulus (CS) and a primary reward in either paradigm. In the autoshaping experiment, PPTg-lesioned rats approached the CS+ and CS- with equal frequency, and the latencies to respond to the two stimuli did not differ. PPTg lesions also disrupted discriminated approaches to an appetitive CS in the CRf paradigm and completely abolished the acquisition of responding with CRf. These data are discussed in the context of a possible cognitive function of the PPTg, particularly in terms of lesion-induced disruptions of attentional processes that are mediated by the thalamus.
Stimulus-response time to alarms of the intra-aortic balloon pump: safe care practices
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Andrezza Serpa Franco
Full Text Available ABSTRACT Objective: To characterize the sound alarms of the Intra-Aortic Balloon Pump (IABP during aortic counterpulsation therapy; to measure the stimulus-response time of the team to these; and to discuss the implications of increasing this time for patient safety from the alarm fatigue perspective. Method: This is an observational and descriptive study with quantitative and qualitative approach, case study type, carried out in a Cardiac Surgical Intensive Care Unit. Results: The most audible IABP alarm was the one of high priority increased-reduced diastolic blood pressure. The stimulus-response time was 33.9 seconds on average. Conclusion: Managing the alarms of these equipment is essential to minimize the occurrence of the alarm fatigue phenomenon and to offer a safer assistance to patients who rely on this technology.
Cognitive mechanisms associated with auditory sensory gating
Jones, L.A.; Hills, P.J.; Dick, K.M.; Jones, S.P.; Bright, P.
2016-01-01
Sensory gating is a neurophysiological measure of inhibition that is characterised by a reduction in the P50 event-related potential to a repeated identical stimulus. The objective of this work was to determine the cognitive mechanisms that relate to the neurological phenomenon of auditory sensory gating. Sixty participants underwent a battery of 10 cognitive tasks, including qualitatively different measures of attentional inhibition, working memory, and fluid intelligence. Participants additionally completed a paired-stimulus paradigm as a measure of auditory sensory gating. A correlational analysis revealed that several tasks correlated significantly with sensory gating. However once fluid intelligence and working memory were accounted for, only a measure of latent inhibition and accuracy scores on the continuous performance task showed significant sensitivity to sensory gating. We conclude that sensory gating reflects the identification of goal-irrelevant information at the encoding (input) stage and the subsequent ability to selectively attend to goal-relevant information based on that previous identification. PMID:26716891
Neural correlates of derived relational responding on tests of stimulus equivalence
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Cataldo Michael F
2008-02-01
Full Text Available Abstract Background An essential component of cognition and language involves the formation of new conditional relations between stimuli based upon prior experiences. Results of investigations on transitive inference (TI highlight a prominent role for the medial temporal lobe in maintaining associative relations among sequentially arranged stimuli (A > B > C > D > E. In this investigation, medial temporal lobe activity was assessed while subjects completed "Stimulus Equivalence" (SE tests that required deriving conditional relations among stimuli within a class (A ≡ B ≡ C. Methods Stimuli consisted of six consonant-vowel-consonant triads divided into two classes (A1, B1, C1; A2, B2, C2. A simultaneous matching-to-sample task and differential reinforcement were employed during pretraining to establish the conditional relations A1:B1 and B1:C1 in class 1 and A2:B2 and B2:C2 in class 2. During functional neuroimaging, recombined stimulus pairs were presented and subjects judged (yes/no whether stimuli were related. SE tests involved presenting three different types of within-class pairs: Symmetrical (B1 A1; C1 B1; B2 A2; C2 B2, and Transitive (A1 C1; A2 C2 and Equivalence (C1 A1; C2 A2 relations separated by a nodal stimulus. Cross-class 'Foils' consisting of unrelated stimuli (e.g., A1 C2 were also presented. Results Relative to cross-class Foils, Transitive and Equivalence relations requiring inferential judgments elicited bilateral activation in the anterior hippocampus while Symmetrical relations elicited activation in the parahippocampus. Relative to each derived relation, Foils generally elicited bilateral activation in the parahippocampus, as well as in frontal and parietal lobe regions. Conclusion Activation observed in the hippocampus to nodal-dependent derived conditional relations (Transitive and Equivalence relations highlights its involvement in maintaining relational structure and flexible memory expression among stimuli within a
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Ya-Nan Niu
2016-10-01
Full Text Available Age-related decreases in action are caused by neuromuscular weakness and cognitive decline. Although physical interventions have been reported to have beneficial effects on cognitive function in older adults, whether cognitive training improves action-related function remains unclear. In this study, we investigated the effects of combined cognitive training on intention-based and stimulus-based actions in older adults using event-related potentials (ERPs. A total of 26 healthy older adults (16 in the training group and 10 in the control group participated in the study. The training group received 16 sessions of cognitive training, including 8 sessions of executive function training and 8 sessions of memory strategy training. Before and after training, both groups of participants underwent cognitive assessments and ERP recordings during both the acquisition and test phases with a motor cognitive paradigm. During the acquisition phase, subjects were asked to press one of two keys, either using a self-selected (intention-based method or based on the preceding stimulus (stimulus-based. During the test phase, subjects were asked to respond to the pre-cues with either congruent or incongruent tasks. Using ERP indices—including readiness potential, P3 and contingent negative variation to identify motor preparation, stimulus processing and interference effect, respectively—we revealed the effects of training on both intention-based and stimulus-based actions. The correlations were also computed between the improved cognitive performance and the ERP amplitudes. It was shown that the improved executive function might extend substantial benefits to both actions, whereas associative memory may be specifically related to the bidirectional action-effect association of intention-based action, although the training effect of memory was absent during the insufficient training hours. In sum, the present study provided empirical evidence demonstrating that
Mechanisms of radiation-induced conditioned taste aversion learning
International Nuclear Information System (INIS)
Rabin, B.M.; Hunt, W.A.
1986-01-01
The literature on taste aversion learning is reviewed and discussed, with particular emphasis on those studies that have used exposure to ionizing radiation as an unconditioned stimulus to produce a conditioned taste aversion. The primary aim of the review is to attempt to define the mechanisms that lead to the initiation of the taste aversion response following exposure to ionizing radiation. Studies using drug treatments to produce a taste aversion have been included to the extent that they are relevant to understanding the mechanisms by which exposure to ionizing radiation can affect the behavior of the organism. 141 references
Directional Scanning as a Function of Stimulus Characteristics, Reading Habits, and Directional Set
Nachshon, Israel; And Others
1977-01-01
"32 English readers and 32 Hebrew readers were shown stimuli with directional characteristics (English and Hebrew letters) and stimuli with no directional characteristics (arrays of different circles, bars, colors, and geometric figures) for scanning. The results showed that, while directional stimulus characteristics affected the direction…
Rosen, Maya L; Stern, Chantal E; Michalka, Samantha W; Devaney, Kathryn J; Somers, David C
2015-08-12
been linked to retrieval of vivid memories regardless of space. Here, we investigate possible underlying mechanisms in healthy individuals. We demonstrate two forms of dynamic changes in parietal spatial representations: an asymmetric one for stimulus-guided attention and a symmetric one for long-term memory-guided attention. Copyright © 2015 the authors 0270-6474/15/3511358-06$15.00/0.
Studies in mathematics and mechanics
von Mises, Richard
2013-01-01
Studies in Mathematics and Mechanics is a collection of studies presented to Professor Richard von Mises as a token of reverence and appreciation on the occasion of his seventieth birthday which occurred on April 19, 1953. von Mises' thought has been a stimulus in many seemingly unconnected fields of mathematics, science, and philosophy, to which he has contributed decisive results and new formulations of fundamental concepts. The book contains 42 chapters organized into five parts. Part I contains papers on algebra, number theory and geometry. These include a study of Poincaré's representatio
Davis, Tonya N.; Hodges, Abby; Weston, Regan; Hogan, Emily; Padilla-Mainor, Kristen
2017-01-01
Preferred forms of social interaction were identified using a paired-stimulus format in which two 3-5 s videos of the experimenter providing the social interaction to the participant were presented. Reinforcer efficacy of the high-, medium-, and low-preferred interactions was evaluated using a progressive-ratio schedule to determine the amount of…
Barriers to Engagement in Sleep Restriction and Stimulus Control in Chronic Insomnia
Vincent, Norah; Lewycky, Samantha; Finnegan, Heather
2008-01-01
Sleep restriction (SRT) and stimulus control (SC) have been found to be effective interventions for chronic insomnia (Morgenthaler et al., 2006), and yet adherence to SRT and SC varies widely. The objective of this study was to investigate correlates to adherence to SC/SRT among 40 outpatients with primary or comorbid insomnia using a…
Rodriguez, Paul F.
2009-01-01
Memory systems are known to be influenced by feedback and error processing, but it is not well known what aspects of outcome contingencies are related to different memory systems. Here we use the Rescorla-Wagner model to estimate prediction errors in an fMRI study of stimulus-outcome association learning. The conditional probabilities of outcomes…
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Baird Bill
2006-02-01
Full Text Available Abstract Background: A new method has been used to obtain human sensory evoked-responses whose time-domain waveforms have been undetectable by previous methods. These newly discovered evoked-responses have durations that exceed the time between the stimuli in a continuous stream, thus causing an overlap which, up to now, has prevented their detection. We have named them "A-waves", and added a prefix to show the sensory system from which the responses were obtained (visA-waves, audA-waves, somA-waves. Results: When A-waves were studied as a function of stimulus repetition-rate, it was found that there were systematic differences in waveshape at repetition-rates above and below the psychophysical region in which the sensation of individual stimuli fuse into a continuity. The fusion phenomena is sometimes measured by a "Critical Fusion Frequency", but for this research we can only identify a frequency-region [which we call the STZ (Sensation-Transition Zone]. Thus, the A-waves above the STZ differed from those below the STZ, as did the sensations. Study of the psychophysical differences in auditory and visual stimuli, as shown in this paper, suggest that different stimulus features are detected, and remembered, at stimulation rates above and below STZ. Conclusion: The results motivate us to speculate that: 1 Stimulus repetition-rates above the STZ generate waveforms which underlie "fusion-memory" whereas rates below the STZ show neuronal processing in which "flash-memory" occurs. 2 These two memories differ in both duration and mechanism, though they may occur in the same cell groups. 3 The differences in neuronal processing may be related to "figure" and "ground" differentiation. We conclude that A-waves provide a novel measure of neural processes that can be detected on the human scalp, and speculate that they may extend clinical applications of evoked response recordings. If A-waves also occur in animals, it is likely that A-waves will provide
Jewett, Don L; Hart, Toryalai; Larson-Prior, Linda J; Baird, Bill; Olson, Marram; Trumpis, Michael; Makayed, Katherine; Bavafa, Payam
2006-01-01
Background: A new method has been used to obtain human sensory evoked-responses whose time-domain waveforms have been undetectable by previous methods. These newly discovered evoked-responses have durations that exceed the time between the stimuli in a continuous stream, thus causing an overlap which, up to now, has prevented their detection. We have named them "A-waves", and added a prefix to show the sensory system from which the responses were obtained (visA-waves, audA-waves, somA-waves). Results: When A-waves were studied as a function of stimulus repetition-rate, it was found that there were systematic differences in waveshape at repetition-rates above and below the psychophysical region in which the sensation of individual stimuli fuse into a continuity. The fusion phenomena is sometimes measured by a "Critical Fusion Frequency", but for this research we can only identify a frequency-region [which we call the STZ (Sensation-Transition Zone)]. Thus, the A-waves above the STZ differed from those below the STZ, as did the sensations. Study of the psychophysical differences in auditory and visual stimuli, as shown in this paper, suggest that different stimulus features are detected, and remembered, at stimulation rates above and below STZ. Conclusion: The results motivate us to speculate that: 1) Stimulus repetition-rates above the STZ generate waveforms which underlie "fusion-memory" whereas rates below the STZ show neuronal processing in which "flash-memory" occurs. 2) These two memories differ in both duration and mechanism, though they may occur in the same cell groups. 3) The differences in neuronal processing may be related to "figure" and "ground" differentiation. We conclude that A-waves provide a novel measure of neural processes that can be detected on the human scalp, and speculate that they may extend clinical applications of evoked response recordings. If A-waves also occur in animals, it is likely that A-waves will provide new methods for
Silvani, Alessandro; Calandra-Buonaura, Giovanna; Johnson, Blair D.; van Helmond, Noud; Barletta, Giorgio; Cecere, Anna G.; Joyner, Michael J.; Cortelli, Pietro
2017-01-01
The upright posture strengthens the coupling between heart period (HP) and systolic arterial pressure (SAP) consistently with a greater contribution of the arterial baroreflex to cardiac control, while paradoxically decreasing cardiac baroreflex sensitivity (cBRS). To investigate the physiological mechanisms that mediate the coupling between HP and SAP in response to different postures, we analyzed the cross-correlation functions between low-frequency HP and SAP fluctuations and estimated cBR...
Effects of stimulus response compatibility on covert imitation of vowels.
Adank, Patti; Nuttall, Helen; Bekkering, Harold; Maegherman, Gwijde
2018-03-13
When we observe someone else speaking, we tend to automatically activate the corresponding speech motor patterns. When listening, we therefore covertly imitate the observed speech. Simulation theories of speech perception propose that covert imitation of speech motor patterns supports speech perception. Covert imitation of speech has been studied with interference paradigms, including the stimulus-response compatibility paradigm (SRC). The SRC paradigm measures covert imitation by comparing articulation of a prompt following exposure to a distracter. Responses tend to be faster for congruent than for incongruent distracters; thus, showing evidence of covert imitation. Simulation accounts propose a key role for covert imitation in speech perception. However, covert imitation has thus far only been demonstrated for a select class of speech sounds, namely consonants, and it is unclear whether covert imitation extends to vowels. We aimed to demonstrate that covert imitation effects as measured with the SRC paradigm extend to vowels, in two experiments. We examined whether covert imitation occurs for vowels in a consonant-vowel-consonant context in visual, audio, and audiovisual modalities. We presented the prompt at four time points to examine how covert imitation varied over the distracter's duration. The results of both experiments clearly demonstrated covert imitation effects for vowels, thus supporting simulation theories of speech perception. Covert imitation was not affected by stimulus modality and was maximal for later time points.
Skill learning and the evolution of social learning mechanisms.
van der Post, Daniel J; Franz, Mathias; Laland, Kevin N
2016-08-24
Social learning is potentially advantageous, but evolutionary theory predicts that (i) its benefits may be self-limiting because social learning can lead to information parasitism, and (ii) these limitations can be mitigated via forms of selective copying. However, these findings arise from a functional approach in which learning mechanisms are not specified, and which assumes that social learning avoids the costs of asocial learning but does not produce information about the environment. Whether these findings generalize to all kinds of social learning remains to be established. Using a detailed multi-scale evolutionary model, we investigate the payoffs and information production processes of specific social learning mechanisms (including local enhancement, stimulus enhancement and observational learning) and their evolutionary consequences in the context of skill learning in foraging groups. We find that local enhancement does not benefit foraging success, but could evolve as a side-effect of grouping. In contrast, stimulus enhancement and observational learning can be beneficial across a wide range of environmental conditions because they generate opportunities for new learning outcomes. In contrast to much existing theory, we find that the functional outcomes of social learning are mechanism specific. Social learning nearly always produces information about the environment, and does not always avoid the costs of asocial learning or support information parasitism. Our study supports work emphasizing the value of incorporating mechanistic detail in functional analyses.
Mainsah, B. O.; Reeves, G.; Collins, L. M.; Throckmorton, C. S.
2017-08-01
Objective. The role of a brain-computer interface (BCI) is to discern a user’s intended message or action by extracting and decoding relevant information from brain signals. Stimulus-driven BCIs, such as the P300 speller, rely on detecting event-related potentials (ERPs) in response to a user attending to relevant or target stimulus events. However, this process is error-prone because the ERPs are embedded in noisy electroencephalography (EEG) data, representing a fundamental problem in communication of the uncertainty in the information that is received during noisy transmission. A BCI can be modeled as a noisy communication system and an information-theoretic approach can be exploited to design a stimulus presentation paradigm to maximize the information content that is presented to the user. However, previous methods that focused on designing error-correcting codes failed to provide significant performance improvements due to underestimating the effects of psycho-physiological factors on the P300 ERP elicitation process and a limited ability to predict online performance with their proposed methods. Maximizing the information rate favors the selection of stimulus presentation patterns with increased target presentation frequency, which exacerbates refractory effects and negatively impacts performance within the context of an oddball paradigm. An information-theoretic approach that seeks to understand the fundamental trade-off between information rate and reliability is desirable. Approach. We developed a performance-based paradigm (PBP) by tuning specific parameters of the stimulus presentation paradigm to maximize performance while minimizing refractory effects. We used a probabilistic-based performance prediction method as an evaluation criterion to select a final configuration of the PBP. Main results. With our PBP, we demonstrate statistically significant improvements in online performance, both in accuracy and spelling rate, compared to the conventional
Directory of Open Access Journals (Sweden)
Jorrit S. Montijn
2014-06-01
Full Text Available The primary visual cortex is an excellent model system for investigating how neuronal populations encode information, because of well-documented relationships between stimulus characteristics and neuronal activation patterns. We used two-photon calcium imaging data to relate the performance of different methods for studying population coding (population vectors, template matching, and Bayesian decoding algorithms to their underlying assumptions. We show that the variability of neuronal responses may hamper the decoding of population activity, and that a normalization to correct for this variability may be of critical importance for correct decoding of population activity. Second, by comparing noise correlations and stimulus tuning we find that these properties have dissociated anatomical correlates, even though noise correlations have been previously hypothesized to reflect common synaptic input. We hypothesize that noise correlations arise from large non-specific increases in spiking activity acting on many weak synapses simultaneously, while neuronal stimulus response properties are dependent on more reliable connections. Finally, this paper provides practical guidelines for further research on population coding and shows that population coding cannot be approximated by a simple summation of inputs, but is heavily influenced by factors such as input reliability and noise correlation structure.
The poverty of the stimulus: Quine and Wittgenstein
Directory of Open Access Journals (Sweden)
O’Sullivan Michael
2014-01-01
Full Text Available Quine and Wittgenstein were dominant figures in philosophy in the middle of the twentieth century. Many readers, like Quine himself, have felt that there are deep similarities between the two thinkers, though those similarities are difficult to articulate. I argue that they share the project of understanding the meaning of utterances by reference to the environment of the speaker, though they understand that environment in radically different ways. In particular, Quine has a much thinner conception of the environment than does Wittgenstein. For Quine, the stimulus is impoverished in a way that it is not for Wittgenstein. I also argue that they share a certain deflationary approach to ontology.
Memory and convulsive stimulation: effects of stimulus waveform.
Spanis, C W; Squire, L R
1981-09-01
Electrical stimulation with brief pulses can produce a seizure requiring less energy than conventional sine-wave stimulation, and it has been suggested that brief-pulse stimulation might reduce the memory loss associated with electroconvulsive therapy (ECT). The authors evaluated the effects of electroconvulsive shock (ECS) on memory in mice by using various waveforms, current intensities, training-ECS intervals, pulse widths, and stimulus durations. When equated for ability to produce seizures, low-energy, brief-pulse stimulation caused as much amnesia as sine-wave stimulation and sometimes more. In the absence of comparisons of the amnesic effects of brief-pulse and sine-wave stimulation in humans, the use of brief pulses for administering ECT is unwarranted.
Energy Technology Data Exchange (ETDEWEB)
Liu, Dong, E-mail: ld20501@126.com; Chen, Chuansong, E-mail: chencs@sdnu.edu.cn; Man, Baoyuan, E-mail: byman@sdnu.edu.cn; Meng, Xue; Sun, Yanna, E-mail: sunyuannaa@163.com; Li, Feifei
2016-08-15
Highlights: • Investigate the evolution and succession of three types of fs-laser induced periodic surface structures (FLIPSSs). • Achieve the laser processing window of each type of the FLIPSS. • Explain the formation and evolvement of the ripple structure in the respective of surface plasma wave (SPW). • Ascribe the interaction between the transmitted laser and the reflected laser at the two surfaces of the biconvex lens to the formation of ring structure. - Abstract: This work investigates the femtosencond laser (fs-laser) induced periodical surface structures (FLIPSS) on titanium plate including the concentric rings, microgrooves and subwavelength ripples. The evolution of the three types of the structures at different laser fluence and shot number is investigated experimentally in detail. The competition mechanisms exist among the different FLIPSS. A processing window for each resulting FLIPSS is obtained. In order to give an overall understanding of the FLIPSS, the formation mechanisms of each type of FLIPSS are discussed. The formation of the ripples is well explained by the propagating of the surface plasma wave (SPW) on the air/Ti interface. The evolutions of the ripple distribution are well understood according to this model as well. It is concluded that the interaction of the scattered wave of the laser light with the surface wave is concluded to give rise to the microgroove structure. According to our observation, the shape of the concentric rings does not change with the variation of the laser fluence and pulse number. The structure could be originated from the optical interference between the transmitted and reflected laser beams by the two surfaces of the biconvex lens. This investigation could not only make a further understanding of the formations of FLIPSS but also provide the possibility to control the surface morphologies in laser processing.
International Nuclear Information System (INIS)
Shimazaki, Hideaki
2013-01-01
Neurons in cortical circuits exhibit coordinated spiking activity, and can produce correlated synchronous spikes during behavior and cognition. We recently developed a method for estimating the dynamics of correlated ensemble activity by combining a model of simultaneous neuronal interactions (e.g., a spin-glass model) with a state-space method (Shimazaki et al. 2012 PLoS Comput Biol 8 e1002385). This method allows us to estimate stimulus-evoked dynamics of neuronal interactions which is reproducible in repeated trials under identical experimental conditions. However, the method may not be suitable for detecting stimulus responses if the neuronal dynamics exhibits significant variability across trials. In addition, the previous model does not include effects of past spiking activity of the neurons on the current state of ensemble activity. In this study, we develop a parametric method for simultaneously estimating the stimulus and spike-history effects on the ensemble activity from single-trial data even if the neurons exhibit dynamics that is largely unrelated to these effects. For this goal, we model ensemble neuronal activity as a latent process and include the stimulus and spike-history effects as exogenous inputs to the latent process. We develop an expectation-maximization algorithm that simultaneously achieves estimation of the latent process, stimulus responses, and spike-history effects. The proposed method is useful to analyze an interaction of internal cortical states and sensory evoked activity
The impact of stimulus complexity and frequency swapping on stabilization of binocular rivalry
DEFF Research Database (Denmark)
Sandberg, Kristian; Bahrami, B; Lindeløv, Jonas Kristoffer
2011-01-01
high-level perceptual content. We conclude that overlaps at low visual stages are the most likely cause of the eye-specific stabilization for both stimulus types. Additionally, we examined the impact of swapping the flicker frequency of the images and found a general impact on stabilization...
Developing a Projective Drawing Test: Experiences with the Face Stimulus Assessment (FSA).
Betts, Donna J.
2003-01-01
Describes the experience of creating and working with the Face Stimulus Assessment (FSA). Six samples of the FSA completed by clients with multiple disabilities are presented. As the FSA is a work in progress and has yet to be established as a valid and reliable assessment, implications for further research are also discussed. (Contains 32…
Have Postwar Fiscal Stimulus Policies Met the “Timely, Targeted, and Temporary” Principle?
Directory of Open Access Journals (Sweden)
Jason E. Taylor
2017-06-01
Full Text Available President Barack Obama noted that fiscal stimulus polices should follow three T’s—timely, targeted, and temporary. This paper examines the government’s fiscal response to eleven postwar recessions in light of the three T’s. We find that the record is mixed at best. On average it took 10.9 months before a recession’s start and the first major countercyclical fiscal policy action. Additionally, in half of the eight recessions in which fiscal policy was attempted, the level of real per capita government spending was nearly three times its trend level four years after the recession was over—i.e. the stimulus was not temporary. Finally, with respect to targeted, while some countercyclical policies have been designed to help sectors that were particularly harmed during a recession, we find many cases whereby recessions provided politicians an avenue in which to implement policies that were part of their long-run reform agenda rather than being carefully targeted countercyclical fiscal policy.
Stimulus fear-relevance and the vicarious learning pathway to childhood fears
Askew, C.; Dunne, G.; Ozdil, A.; Reynolds, G.; Field, A.P.
2013-01-01
Enhanced fear learning for fear-relevant stimuli has been demonstrated in procedures with adults in the laboratory. Three experiments investigated the effect of stimulus fear-relevance on vicarious fear learning in children (aged 6-11 years). Pictures of stimuli with different levels of fear-relevance (flowers, caterpillars, snakes, worms, and Australian marsupials) were presented alone or together with scared faces. In line with previous studies, children's fear beliefs and avoidance prefere...
Reilly, Steve; Grutzmacher, Richard P.
2002-07-31
The present experiments were designed to determine if repeated presentations of an empty sipper tube (the conditioned stimulus or CS) with the response-independent delivery of a sucrose solution (the unconditioned stimulus or US) from a second spout results in the development of Pavlovian conditioned responding. In Experiment 1, rats in the experimental condition received paired CS-US presentations whereas subjects in the control condition were exposed to random presentations of CS and US. In Experiment 2, an additional control condition (CS alone) was included and, to encourage generalized responding between the US and CS, the CS tube was filled with water for all groups. The results of both experiments indicate that the CS-directed responding in the paired CS-US condition was Pavlovian in nature. Thus, the present procedure serves as an autoshaping task in which conditioned licking is generated.
A stimulus control technique for improving the efficacy of an established toilet training program.
Taylor, S; Cipani, E; Clardy, A
1994-06-01
Standard toilet training regimens used with children with developmental disabilities have demonstrated effectiveness at achieving bladder and bowel continence. However, in some clinical applications in everyday practice, success has not been achieved, necessitating research into possible modifications of the current approaches. A widely used toilet training program was modified to reduce toileting accidents of a referred child. The modification involved the assessment of the discriminative stimulus for eliminating, namely, his undergarments. By removing the undergarments when an elimination became imminent, an "errorless" learning paradigm was established that allowed for more rapid and enduring acquisition of toileting skills than seen in previous training attempts. The results indicate the present procedure could expedite training for individuals who are difficult to teach appropriate toileting skills through an analysis of the controlling antecedent stimulus for accidents and subsequent manipulation of such stimuli.
A sled push stimulus potentiates subsequent 20-m sprint performance.
Seitz, Laurent B; Mina, Minas A; Haff, G Gregory
2017-08-01
The objective of this study was to examine the potentiating effects of performing a single sprint-style sled push on subsequent unresisted 20m sprint performance. Randomized crossover design. Following a familiarization session, twenty rugby league players performed maximal unresisted 20m sprints before and 15s, 4, 8 and 12min after a single sled push stimulus loaded with either 75 or 125% body mass. The two sled push conditions were performed in a randomized order over a one-week period. The fastest sprint time recorded before each sled push was compared to that recorded at each time point after to determine the post-activation potentiation (PAP) effect. After the 75% body mass sled push, sprint time was 0.26±1.03% slower at the 15s time point (effect size [ES]=0.07) but faster at the 4 (-0.95±2.00%; ES=-0.22), 8 (-1.80±1.43%; ES=-0.42) and 12 (-1.54±1.54%; ES=-0.36)min time points. Sprint time was slower at all the time points after the 125% body mass sled (1.36±2.36%-2.59±2.90%; ESs=0.34-0.64). Twenty-meter sprint performance is potentiated 4-12min following a sled push loaded with 75% body mass while it is impaired after a 125% body mass sled. These results are of great importance for coaches seeking to potentiate sprint performance with the sled push exercise. Copyright © 2017 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.
Transfers of stimulus function during roulette wagering.
Dixon, Mark R; Enoch, Mary Rachel; Belisle, Jordan
2017-10-01
Twenty-five recreational gamblers were initially asked to place bets on either red or black positions on a roulette board in a simulated casino setting. Each participant was then exposed to a stimulus pairing observing procedure which attempted to develop equivalence classes between one color (black or red) and traditionally positive words (e.g., love, happy, sex) and another color (black or red) and traditionally negative words (e.g., death, cancer, taxes), in the absence of consequence manipulations. Twenty-one of the twenty-five participants demonstrated greater response allocation to the color position on the roulette board that participated in a relational network with the positive words. Variations in sequencing of experimental conditions had no impact on poststimulus-pairing wagers, but did impact tests for equivalence accuracy. © 2017 Society for the Experimental Analysis of Behavior.
Ten Oever, Sanne; Sack, Alexander T; Wheat, Katherine L; Bien, Nina; van Atteveldt, Nienke
2013-01-01
Content and temporal cues have been shown to interact during audio-visual (AV) speech identification. Typically, the most reliable unimodal cue is used more strongly to identify specific speech features; however, visual cues are only used if the AV stimuli are presented within a certain temporal window of integration (TWI). This suggests that temporal cues denote whether unimodal stimuli belong together, that is, whether they should be integrated. It is not known whether temporal cues also provide information about the identity of a syllable. Since spoken syllables have naturally varying AV onset asynchronies, we hypothesize that for suboptimal AV cues presented within the TWI, information about the natural AV onset differences can aid in speech identification. To test this, we presented low-intensity auditory syllables concurrently with visual speech signals, and varied the stimulus onset asynchronies (SOA) of the AV pair, while participants were instructed to identify the auditory syllables. We revealed that specific speech features (e.g., voicing) were identified by relying primarily on one modality (e.g., auditory). Additionally, we showed a wide window in which visual information influenced auditory perception, that seemed even wider for congruent stimulus pairs. Finally, we found a specific response pattern across the SOA range for syllables that were not reliably identified by the unimodal cues, which we explained as the result of the use of natural onset differences between AV speech signals. This indicates that temporal cues not only provide information about the temporal integration of AV stimuli, but additionally convey information about the identity of AV pairs. These results provide a detailed behavioral basis for further neuro-imaging and stimulation studies to unravel the neurofunctional mechanisms of the audio-visual-temporal interplay within speech perception.
Hasenstab, Kathryn A; Sitaram, Swetha; Lang, Ivan M; Shaker, Reza; Jadcherla, Sudarshan R
2018-02-01
Pharyngeal-provocation induced aerodigestive symptoms in infants remain an enigma. Sources of pharyngeal provocation can be anterograde as with feeding, and retrograde as in gastroesophageal reflux. We determined maturational and dose-response effects of targeted pharyngeal-stimulus on frequency, stability, and magnitude of pharyngeal and respiratory waveforms during multiple pharyngeal swallowing responses in preterm-born infants when they were of full-term postmenstrual age (PMA). Eighteen infants (11 male) were studied longitudinally at 39.8 ± 4.8 weeks PMA (time-1) and 44.1 ± 5.8 weeks PMA (time-2). Infants underwent concurrent pharyngo-esophageal manometry, respiratory inductance plethysmography, and nasal airflow thermistor methods to test sensory-motor interactions between the pharynx, esophagus, and airway. Linear mixed models were used and data presented as mean ± SEM or %. Overall, responses to 250 stimuli were analyzed. Of the multiple pharyngeal swallowing responses (n = 160), with maturation (a) deglutition apnea duration decreases (p 0.05), and (c) respiratory changes were unaffected (p > 0.05). Initial and subsequent pharyngeal responses and respiratory rhythm interactions become more distinct with maturation. Interval oromotor experiences and volume-dependent increase in adaptive responses may be contributory. These mechanisms may be important in modulating and restoring respiratory rhythm normalcy.
Leung, Kawai; Mohammadi, Aylia; Ryu, William; Nemenman, Ilya
In animals, we must infer the pain level from experimental characterization of behavior. This is not trivial since behaviors are very complex and multidimensional. To establish C.elegans as a model for pain research, we propose for the first time a quantitative model that allows inference of a thermal nociceptive stimulus level from the behavior of an individual worm. We apply controlled levels of pain by locally heating worms with an infrared laser and capturing the subsequent behavior. We discover that the behavioral response is a product of stereotypical behavior and a nonlinear function of the strength of stimulus. The same stereotypical behavior is observed in normal, anesthetized and mutated worms. From this result we build a Bayesian model to infer the strength of laser stimulus from the behavior. This model allows us to measure the efficacy of anaesthetization and mutation by comparing the inferred strength of stimulus. Based on the measured nociceptive escape of over 200 worms, our model is able to significantly differentiate normal, anaesthetized and mutated worms with 40 worm samples. This work was partially supported by NSF Grant No. IOS/1208126 and HFSP Grant No. RGY0084/.
Baladi, Michelle G; France, Charles P
2010-10-01
Discriminative stimulus effects of direct acting dopamine receptor agonists (e.g. quinpirole) appear to be mediated by D3 receptors in free-feeding rats. Free access to high-fat chow increases sensitivity to quinpirole-induced yawning, and this study examined whether eating high-fat chow increases sensitivity to the discriminative stimulus effects of quinpirole. Five rats discriminated between 0.032 mg/kg quinpirole and vehicle while responding under a continuous reinforcement schedule of stimulus shock termination. When rats had free access to high-fat chow (discrimination training was suspended), the quinpirole discrimination dose-response curve shifted leftward, possibly indicating enhanced sensitivity at D3 receptors. In the same rats, both the ascending (mediated by D3 receptors) and descending (mediated by D2 receptors) limbs of the dose-response curve for quinpirole-induced yawning shifted leftward. When rats had free access to a standard chow (discrimination training was suspended), the quinpirole discrimination and yawning dose-response curves did not change. Together with published data showing that the discriminative stimulus effects of quinpirole in free-feeding rats are mediated by D3 receptors and the insensitivity of this effect of quinpirole to food restriction (shown to increase sensitivity to D2 but not D3-mediated effects), these results suggest that the leftward shift of the discrimination dose-response curve when rats eat high-fat chow is likely because of enhanced sensitivity at D3 receptors. Thus, eating high-fat food enhances drug effects in a manner that might impact clinical effects of drugs or vulnerability to drug abuse.
Baladi, Michelle G; France, Charles P
2010-01-01
Discriminative stimulus effects of directly-acting dopamine receptor agonists (e.g. quinpirole) appear to be mediated by D3 receptors in free-feeding rats. Free access to high fat chow increases sensitivity to quinpirole-induced yawning and the current study examined whether eating high fat chow increases sensitivity to the discriminative stimulus effects of quinpirole. Five rats discriminated between 0.032 mg/kg quinpirole and vehicle while responding under a continuous reinforcement schedule of stimulus shock termination. When rats had free access to high fat chow (discrimination training was suspended), the quinpirole discrimination dose-response curve shifted leftward, possibly indicating enhanced sensitivity at D3 receptors. In the same rats, both the ascending (mediated by D3 receptors) and descending (mediated by D2 receptors) limbs of the dose- response curve for quinpirole-induced yawning shifted leftward. When rats had free access to a standard chow (discrimination training was suspended), the quinpirole discrimination and yawning dose-response curves did not change. Together with published data showing that the discriminative stimulus effects of quinpirole in free- feeding rats are mediated by D3 receptors and the insensitivity of this effect of quinpirole to food restriction (shown to increase sensitivity to D2 but not D3-mediated effects), these results suggest that the leftward shift of the discrimination dose-response curve when rats eat high fat chow is likely due to enhanced sensitivity at D3 receptors. Thus, eating high fat food enhances drug effects in a manner that might impact clinical effects of drugs or vulnerability to drug abuse. PMID:20729718
Dickson, Price E.; Corkill, Beau; McKimm, Eric; Miller, Mellessa M.; Calton, Michele A.; Goldowitz, Daniel; Blaha, Charles D.; Mittleman, Guy
2013-01-01
Fragile X syndrome (FXS) is the most common inherited form of intellectual disability in males and the most common genetic cause of autism. Although executive dysfunction is consistently found in humans with FXS, evidence of executive dysfunction in Fmr1 KO mice, a mouse model of FXS, has been inconsistent. One possible explanation for this is that executive dysfunction in Fmr1 KO mice, similar to humans with FXS, is only evident when cognitive demands are high. Using touchscreen operant conditioning chambers, male Fmr1 KO mice and their male wildtype littermates were tested on the acquisition of a pairwise visual discrimination followed by four serial reversals of the response rule. We assessed reversal learning performance under two different conditions. In the first, the correct stimulus was salient and the incorrect stimulus was non-salient. In the second and more challenging condition, the incorrect stimulus was salient and the correct stimulus was non-salient; this increased cognitive load by introducing conflict between sensory-driven (i.e., bottom-up) and task-dependent (i.e., top-down) signals. Fmr1 KOs displayed two distinct impairments relative to wildtype littermates. First, Fmr1 KOs committed significantly more learning-type errors during the second reversal stage, but only under high cognitive load. Second, during the first reversal stage, Fmr1 KOs committed significantly more attempts to collect a reward during the timeout following an incorrect response. These findings indicate that Fmr1 KO mice display executive dysfunction that, in some cases, is only evident under high cognitive load. PMID:23747611
The influence of attention and reward on the learning of stimulus-response associations
Vartak, Devavrat; Jeurissen, Danique; Self, Matthew W; Roelfsema, Pieter R
2017-01-01
We can learn new tasks by listening to a teacher, but we can also learn by trial-and-error. Here, we investigate the factors that determine how participants learn new stimulus-response mappings by trial-and-error. Does learning in human observers comply with reinforcement learning theories, which
Dispersion Differences and Consistency of Artificial Periodic Structures.
Cheng, Zhi-Bao; Lin, Wen-Kai; Shi, Zhi-Fei
2017-10-01
Dispersion differences and consistency of artificial periodic structures, including phononic crystals, elastic metamaterials, as well as periodic structures composited of phononic crystals and elastic metamaterials, are investigated in this paper. By developing a K(ω) method, complex dispersion relations and group/phase velocity curves of both the single-mechanism periodic structures and the mixing-mechanism periodic structures are calculated at first, from which dispersion differences of artificial periodic structures are discussed. Then, based on a unified formulation, dispersion consistency of artificial periodic structures is investigated. Through a comprehensive comparison study, the correctness for the unified formulation is verified. Mathematical derivations of the unified formulation for different artificial periodic structures are presented. Furthermore, physical meanings of the unified formulation are discussed in the energy-state space.
Hakkarainen, Elina; Pirila, Silja; Kaartinen, Jukka; van der Meere, Jaap J.
The study investigated stimulus evaluation time, event preparation, and motor action planning of patients with mild spastic cerebral palsy and a peer control group in the age range of 9 to 18 years. To this end, participants were carrying out a stimulus recognition task. Findings indicated an
Hippocampus duality: Memory and novelty detection are subserved by distinct mechanisms.
Barbeau, Emmanuel J; Chauvel, Patrick; Moulin, Christopher J A; Regis, Jean; Liégeois-Chauvel, Catherine
2017-04-01
The hippocampus plays a pivotal role both in novelty detection and in long-term memory. The physiological mechanisms underlying these behaviors have yet to be understood in humans. We recorded intracerebral evoked potentials within the hippocampus of epileptic patients (n = 10) during both memory and novelty detection tasks (targets in oddball tasks). We found that memory and detection tasks elicited late local field potentials in the hippocampus during the same period, but of opposite polarity (negative during novelty detection tasks, positive during memory tasks, ∼260-600 ms poststimulus onset, P < 0.05). Critically, these potentials had maximal amplitude on the same contact in the hippocampus for each patient. This pattern did not depend on the task as different types of memory and novelty detection tasks were used. It did not depend on the novelty of the stimulus or the difficulty of the task either. Two different hypotheses are discussed to account for this result: it is either due to the activation of CA1 pyramidal neurons by two different pathways such as the monosynaptic and trisynaptic entorhinal-hippocampus pathways, or to the activation of different neuronal populations, that is, differing either functionally (e.g., novelty/familiarity neurons) or located in different regions of the hippocampus (e.g., CA1/subiculum). In either case, these activities may integrate the activity of two distinct large-scale networks implementing externally or internally oriented, mutually exclusive, brain states. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.
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Marco Hirnstein
Full Text Available It is well known that the planum temporale (PT area in the posterior temporal lobe carries out spectro-temporal analysis of auditory stimuli, which is crucial for speech, for example. There are suggestions that the PT is also involved in auditory attention, specifically in the discrimination and selection of stimuli from the left and right ear. However, direct evidence is missing so far. To examine the role of the PT in auditory attention we asked fourteen participants to complete the Bergen Dichotic Listening Test. In this test two different consonant-vowel syllables (e.g., "ba" and "da" are presented simultaneously, one to each ear, and participants are asked to verbally report the syllable they heard best or most clearly. Thus attentional selection of a syllable is stimulus-driven. Each participant completed the test three times: after their left and right PT (located with anatomical brain scans had been stimulated with repetitive transcranial magnetic stimulation (rTMS, which transiently interferes with normal brain functioning in the stimulated sites, and after sham stimulation, where participants were led to believe they had been stimulated but no rTMS was applied (control. After sham stimulation the typical right ear advantage emerged, that is, participants reported relatively more right than left ear syllables, reflecting a left-hemispheric dominance for language. rTMS over the right but not left PT significantly reduced the right ear advantage. This was the result of participants reporting more left and fewer right ear syllables after right PT stimulation, suggesting there was a leftward shift in stimulus selection. Taken together, our findings point to a new function of the PT in addition to auditory perception: particularly the right PT is involved in stimulus selection and (stimulus-driven, auditory attention.