Carving Executive Control at Its Joints: Working Memory Capacity Predicts Stimulus-Stimulus, but Not Stimulus-Response, Conflict

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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),…

The use of faces as stimuli in neuroimaging and psychological experiments: a procedure to standardize stimulus features.

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Gronenschild, Ed H B M; Smeets, Floortje; Vuurman, Eric F P M; van Boxtel, Martin P J; Jolles, Jelle

2009-11-01

In psychological experiments involving facial stimuli, it is of great importance that the basic perceptual or psychological characteristics that are investigated are not confounded by factors such as brightness and contrast, head size, hair cut and color, skin color, and the presence of glasses and earrings. Standardization of facial stimulus materials reduces the effect of these confounding factors. We therefore employed a set of basic image processing techniques to deal with this issue. The processed images depict the faces in grayscale, all at the same size, brightness, and contrast, and confined to an oval mask revealing only the basic features such as the eyes, nose, and mouth. The standardization was successfully applied to four different face databases, consisting of male and female faces and including neutral as well as happy facial expressions. An important advantage of the proposed standardization is that featural as well as configurational information is retained. We also consider the procedure to be a major contribution to the development of a de facto standard for the use of facial stimuli in psychological experiments. Such methodological standardization would allow a better comparison of the results of these studies.

Attentional Selection of Feature Conjunctions Is Accomplished by Parallel and Independent Selection of Single Features.

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Andersen, Søren K; Müller, Matthias M; Hillyard, Steven A

2015-07-08

Experiments that study feature-based attention have often examined situations in which selection is based on a single feature (e.g., the color red). However, in more complex situations relevant stimuli may not be set apart from other stimuli by a single defining property but by a specific combination of features. Here, we examined sustained attentional selection of stimuli defined by conjunctions of color and orientation. Human observers attended to one out of four concurrently presented superimposed fields of randomly moving horizontal or vertical bars of red or blue color to detect brief intervals of coherent motion. Selective stimulus processing in early visual cortex was assessed by recordings of steady-state visual evoked potentials (SSVEPs) elicited by each of the flickering fields of stimuli. We directly contrasted attentional selection of single features and feature conjunctions and found that SSVEP amplitudes on conditions in which selection was based on a single feature only (color or orientation) exactly predicted the magnitude of attentional enhancement of SSVEPs when attending to a conjunction of both features. Furthermore, enhanced SSVEP amplitudes elicited by attended stimuli were accompanied by equivalent reductions of SSVEP amplitudes elicited by unattended stimuli in all cases. We conclude that attentional selection of a feature-conjunction stimulus is accomplished by the parallel and independent facilitation of its constituent feature dimensions in early visual cortex. The ability to perceive the world is limited by the brain's processing capacity. Attention affords adaptive behavior by selectively prioritizing processing of relevant stimuli based on their features (location, color, orientation, etc.). We found that attentional mechanisms for selection of different features belonging to the same object operate independently and in parallel: concurrent attentional selection of two stimulus features is simply the sum of attending to each of those

Temporal neural mechanisms underlying conscious access to different levels of facial stimulus contents.

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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

Stimulus-related independent component and voxel-wise analysis of human brain activity during free viewing of a feature film.

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Lahnakoski, Juha M; Salmi, Juha; Jääskeläinen, Iiro P; Lampinen, Jouko; Glerean, Enrico; Tikka, Pia; Sams, Mikko

2012-01-01

Understanding how the brain processes stimuli in a rich natural environment is a fundamental goal of neuroscience. Here, we showed a feature film to 10 healthy volunteers during functional magnetic resonance imaging (fMRI) of hemodynamic brain activity. We then annotated auditory and visual features of the motion picture to inform analysis of the hemodynamic data. The annotations were fitted to both voxel-wise data and brain network time courses extracted by independent component analysis (ICA). Auditory annotations correlated with two independent components (IC) disclosing two functional networks, one responding to variety of auditory stimulation and another responding preferentially to speech but parts of the network also responding to non-verbal communication. Visual feature annotations correlated with four ICs delineating visual areas according to their sensitivity to different visual stimulus features. In comparison, a separate voxel-wise general linear model based analysis disclosed brain areas preferentially responding to sound energy, speech, music, visual contrast edges, body motion and hand motion which largely overlapped the results revealed by ICA. Differences between the results of IC- and voxel-based analyses demonstrate that thorough analysis of voxel time courses is important for understanding the activity of specific sub-areas of the functional networks, while ICA is a valuable tool for revealing novel information about functional connectivity which need not be explained by the predefined model. Our results encourage the use of naturalistic stimuli and tasks in cognitive neuroimaging to study how the brain processes stimuli in rich natural environments.

The perception of regularity in an isochronous stimulus in zebra finches (Taeniopygia guttata) and humans

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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

Feature Binding and the Hebb Repetition Effect

OpenAIRE

Barrett, Maeve

2008-01-01

Previous studies have found no evidence that long-term learning of integrated objects and individual features benefit visual short term memory tasks (Logie, Brockmole, & Vandenbroucke, in press; Olson & Jiang, 2004; Treisman, 2006). These findings may have been due to stimulus interference as a restricted number of features were utilised in these studies to form objects in the stimulus arrays. In these studies, participants would have needed to break apart the features of several objects in a...

Performance breakdown in optimal stimulus decoding.

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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.

[The P300 based brain-computer interface: effect of stimulus position in a stimulus train].

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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.

Stimulus-Related Independent Component and Voxel-Wise Analysis of Human Brain Activity during Free Viewing of a Feature Film

Science.gov (United States)

Lahnakoski, Juha M.; Salmi, Juha; Jääskeläinen, Iiro P.; Lampinen, Jouko; Glerean, Enrico; Tikka, Pia; Sams, Mikko

2012-01-01

Understanding how the brain processes stimuli in a rich natural environment is a fundamental goal of neuroscience. Here, we showed a feature film to 10 healthy volunteers during functional magnetic resonance imaging (fMRI) of hemodynamic brain activity. We then annotated auditory and visual features of the motion picture to inform analysis of the hemodynamic data. The annotations were fitted to both voxel-wise data and brain network time courses extracted by independent component analysis (ICA). Auditory annotations correlated with two independent components (IC) disclosing two functional networks, one responding to variety of auditory stimulation and another responding preferentially to speech but parts of the network also responding to non-verbal communication. Visual feature annotations correlated with four ICs delineating visual areas according to their sensitivity to different visual stimulus features. In comparison, a separate voxel-wise general linear model based analysis disclosed brain areas preferentially responding to sound energy, speech, music, visual contrast edges, body motion and hand motion which largely overlapped the results revealed by ICA. Differences between the results of IC- and voxel-based analyses demonstrate that thorough analysis of voxel time courses is important for understanding the activity of specific sub-areas of the functional networks, while ICA is a valuable tool for revealing novel information about functional connectivity which need not be explained by the predefined model. Our results encourage the use of naturalistic stimuli and tasks in cognitive neuroimaging to study how the brain processes stimuli in rich natural environments. PMID:22496909

Stimulus-related independent component and voxel-wise analysis of human brain activity during free viewing of a feature film.

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Juha M Lahnakoski

Full Text Available Understanding how the brain processes stimuli in a rich natural environment is a fundamental goal of neuroscience. Here, we showed a feature film to 10 healthy volunteers during functional magnetic resonance imaging (fMRI of hemodynamic brain activity. We then annotated auditory and visual features of the motion picture to inform analysis of the hemodynamic data. The annotations were fitted to both voxel-wise data and brain network time courses extracted by independent component analysis (ICA. Auditory annotations correlated with two independent components (IC disclosing two functional networks, one responding to variety of auditory stimulation and another responding preferentially to speech but parts of the network also responding to non-verbal communication. Visual feature annotations correlated with four ICs delineating visual areas according to their sensitivity to different visual stimulus features. In comparison, a separate voxel-wise general linear model based analysis disclosed brain areas preferentially responding to sound energy, speech, music, visual contrast edges, body motion and hand motion which largely overlapped the results revealed by ICA. Differences between the results of IC- and voxel-based analyses demonstrate that thorough analysis of voxel time courses is important for understanding the activity of specific sub-areas of the functional networks, while ICA is a valuable tool for revealing novel information about functional connectivity which need not be explained by the predefined model. Our results encourage the use of naturalistic stimuli and tasks in cognitive neuroimaging to study how the brain processes stimuli in rich natural environments.

Affective salience can reverse the effects of stimulus-driven salience on eye movements in complex scenes

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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.

Stimulus Dependency of Object-Evoked Responses in Human Visual Cortex: An Inverse Problem for Category Specificity

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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

Temporal and spectral profiles of stimulus-stimulus and stimulus-response conflict processing.

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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.

Effective traffic features selection algorithm for cyber-attacks samples

Science.gov (United States)

Li, Yihong; Liu, Fangzheng; Du, Zhenyu

2018-05-01

By studying the defense scheme of Network attacks, this paper propose an effective traffic features selection algorithm based on k-means++ clustering to deal with the problem of high dimensionality of traffic features which extracted from cyber-attacks samples. Firstly, this algorithm divide the original feature set into attack traffic feature set and background traffic feature set by the clustering. Then, we calculates the variation of clustering performance after removing a certain feature. Finally, evaluating the degree of distinctiveness of the feature vector according to the result. Among them, the effective feature vector is whose degree of distinctiveness exceeds the set threshold. The purpose of this paper is to select out the effective features from the extracted original feature set. In this way, it can reduce the dimensionality of the features so as to reduce the space-time overhead of subsequent detection. The experimental results show that the proposed algorithm is feasible and it has some advantages over other selection algorithms.

Visual attention to features by associative learning.

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Gozli, Davood G; Moskowitz, Joshua B; Pratt, Jay

2014-11-01

Expecting a particular stimulus can facilitate processing of that stimulus over others, but what is the fate of other stimuli that are known to co-occur with the expected stimulus? This study examined the impact of learned association on feature-based attention. The findings show that the effectiveness of an uninformative color transient in orienting attention can change by learned associations between colors and the expected target shape. In an initial acquisition phase, participants learned two distinct sequences of stimulus-response-outcome, where stimuli were defined by shape ('S' vs. 'H'), responses were localized key-presses (left vs. right), and outcomes were colors (red vs. green). Next, in a test phase, while expecting a target shape (80% probable), participants showed reliable attentional orienting to the color transient associated with the target shape, and showed no attentional orienting with the color associated with the alternative target shape. This bias seemed to be driven by learned association between shapes and colors, and not modulated by the response. In addition, the bias seemed to depend on observing target-color conjunctions, since encountering the two features disjunctively (without spatiotemporal overlap) did not replicate the findings. We conclude that associative learning - likely mediated by mechanisms underlying visual object representation - can extend the impact of goal-driven attention to features associated with a target stimulus. Copyright © 2014 Elsevier B.V. All rights reserved.

Spatio-temporal brain dynamics in a combined stimulus-stimulus and stimulus-response conflict task.

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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.

Sparse feature learning for instrument identification: Effects of sampling and pooling methods.

Science.gov (United States)

Han, Yoonchang; Lee, Subin; Nam, Juhan; Lee, Kyogu

2016-05-01

Feature learning for music applications has recently received considerable attention from many researchers. This paper reports on the sparse feature learning algorithm for musical instrument identification, and in particular, focuses on the effects of the frame sampling techniques for dictionary learning and the pooling methods for feature aggregation. To this end, two frame sampling techniques are examined that are fixed and proportional random sampling. Furthermore, the effect of using onset frame was analyzed for both of proposed sampling methods. Regarding summarization of the feature activation, a standard deviation pooling method is used and compared with the commonly used max- and average-pooling techniques. Using more than 47 000 recordings of 24 instruments from various performers, playing styles, and dynamics, a number of tuning parameters are experimented including the analysis frame size, the dictionary size, and the type of frequency scaling as well as the different sampling and pooling methods. The results show that the combination of proportional sampling and standard deviation pooling achieve the best overall performance of 95.62% while the optimal parameter set varies among the instrument classes.

Highly Reconfigurable Beamformer Stimulus Generator

Science.gov (United States)

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.

The contributions of numerical acuity and non-numerical stimulus features to the development of the number sense and symbolic math achievement.

Science.gov (United States)

Starr, Ariel; DeWind, Nicholas K; Brannon, Elizabeth M

2017-11-01

Numerical acuity, frequently measured by a Weber fraction derived from nonsymbolic numerical comparison judgments, has been shown to be predictive of mathematical ability. However, recent findings suggest that stimulus controls in these tasks are often insufficiently implemented, and the proposal has been made that alternative visual features or inhibitory control capacities may actually explain this relation. Here, we use a novel mathematical algorithm to parse the relative influence of numerosity from other visual features in nonsymbolic numerical discrimination and to examine the strength of the relations between each of these variables, including inhibitory control, and mathematical ability. We examined these questions developmentally by testing 4-year-old children, 6-year-old children, and adults with a nonsymbolic numerical comparison task, a symbolic math assessment, and a test of inhibitory control. We found that the influence of non-numerical features decreased significantly over development but that numerosity was a primary determinate of decision making at all ages. In addition, numerical acuity was a stronger predictor of math achievement than either non-numerical bias or inhibitory control in children. These results suggest that the ability to selectively attend to number contributes to the maturation of the number sense and that numerical acuity, independent of inhibitory control, contributes to math achievement in early childhood. Copyright © 2017 Elsevier B.V. All rights reserved.

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.

Stimulus Effects on Local Preference: Stimulus-Response Contingencies, Stimulus-Food Pairing, and Stimulus-Food Correlation

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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…

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.

Face recognition via sparse representation of SIFT feature on hexagonal-sampling image

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Zhang, Daming; Zhang, Xueyong; Li, Lu; Liu, Huayong

2018-04-01

This paper investigates a face recognition approach based on Scale Invariant Feature Transform (SIFT) feature and sparse representation. The approach takes advantage of SIFT which is local feature other than holistic feature in classical Sparse Representation based Classification (SRC) algorithm and possesses strong robustness to expression, pose and illumination variations. Since hexagonal image has more inherit merits than square image to make recognition process more efficient, we extract SIFT keypoint in hexagonal-sampling image. Instead of matching SIFT feature, firstly the sparse representation of each SIFT keypoint is given according the constructed dictionary; secondly these sparse vectors are quantized according dictionary; finally each face image is represented by a histogram and these so-called Bag-of-Words vectors are classified by SVM. Due to use of local feature, the proposed method achieves better result even when the number of training sample is small. In the experiments, the proposed method gave higher face recognition rather than other methods in ORL and Yale B face databases; also, the effectiveness of the hexagonal-sampling in the proposed method is verified.

Autoshaping with common and distinctive stimulus elements, compact and dispersed arrays.

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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-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.

Audiovisual Modulation in Mouse Primary Visual Cortex Depends on Cross-Modal Stimulus Configuration and Congruency.

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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

The iso-response method: measuring neuronal stimulus integration with closed-loop experiments

Science.gov (United States)

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

Two Pathways to Stimulus Encoding in Category Learning?

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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

Neuron's eye view: Inferring features of complex stimuli from neural responses.

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Xin Chen

2017-08-01

Full Text Available Experiments that study neural encoding of stimuli at the level of individual neurons typically choose a small set of features present in the world-contrast and luminance for vision, pitch and intensity for sound-and assemble a stimulus set that systematically varies along these dimensions. Subsequent analysis of neural responses to these stimuli typically focuses on regression models, with experimenter-controlled features as predictors and spike counts or firing rates as responses. Unfortunately, this approach requires knowledge in advance about the relevant features coded by a given population of neurons. For domains as complex as social interaction or natural movement, however, the relevant feature space is poorly understood, and an arbitrary a priori choice of features may give rise to confirmation bias. Here, we present a Bayesian model for exploratory data analysis that is capable of automatically identifying the features present in unstructured stimuli based solely on neuronal responses. Our approach is unique within the class of latent state space models of neural activity in that it assumes that firing rates of neurons are sensitive to multiple discrete time-varying features tied to the stimulus, each of which has Markov (or semi-Markov dynamics. That is, we are modeling neural activity as driven by multiple simultaneous stimulus features rather than intrinsic neural dynamics. We derive a fast variational Bayesian inference algorithm and show that it correctly recovers hidden features in synthetic data, as well as ground-truth stimulus features in a prototypical neural dataset. To demonstrate the utility of the algorithm, we also apply it to cluster neural responses and demonstrate successful recovery of features corresponding to monkeys and faces in the image set.

Stimulus properties of nicotine, amphetamine, and chlordiazepoxide as positive features in a pavlovian appetitive discrimination task in rats.

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Palmatier, Matthew I; Wilkinson, Jamie L; Metschke, Dawn M; Bevins, Rick A

2005-04-01

Recent experiments from our laboratory have demonstrated that drug states can signal when environmental cues will be followed by rewarding outcomes (ie Pavlovian conditioning). However, little is known about the generality of this approach and whether it can be used for studying the pharmacological properties of drug states. Accordingly, the present experiments tested the pharmacological specificity of nicotine (0.4 mg/kg), amphetamine (1 mg/kg), and chlordiazepoxide (CDP, 5 mg/kg) in this Pavlovian drug discrimination procedure. Following drug administration, presentation of a conditional stimulus (CS) was followed by brief access to sucrose. When saline was administered, the same CS was presented but sucrose was withheld. In substitution tests, rats in each condition received varying doses of all training drugs and caffeine. Anticipatory food seeking developed during the CS on drug sessions but not on saline sessions for all drug features (ie drug state-specific conditional response (CR)). In generalization tests, this CR decreased as a function of decreases in the training dose. Median effective doses (ED50s) were calculated for nicotine (0.054 mg/kg), amphetamine (0.26 mg/kg), and CDP (2.48 mg/kg). No compound tested substituted for the CDP training drug. Partial substitution was evident between nicotine and amphetamine; CDP did not substitute for either of these drug features. Caffeine fully substituted for nicotine (ED50 = 15.45 mg/kg) and amphetamine (ED50 = 3.70 mg/kg), but not for CDP. These results are consistent with the hypothesis that drug states can occasion appetitive Pavlovian CRs in a pharmacologically specific manner.

Setting and changing feature priorities in visual short-term memory.

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Kalogeropoulou, Zampeta; Jagadeesh, Akshay V; Ohl, Sven; Rolfs, Martin

2017-04-01

Many everyday tasks require prioritizing some visual features over competing ones, both during the selection from the rich sensory input and while maintaining information in visual short-term memory (VSTM). Here, we show that observers can change priorities in VSTM when, initially, they attended to a different feature. Observers reported from memory the orientation of one of two spatially interspersed groups of black and white gratings. Using colored pre-cues (presented before stimulus onset) and retro-cues (presented after stimulus offset) predicting the to-be-reported group, we manipulated observers' feature priorities independently during stimulus encoding and maintenance, respectively. Valid pre-cues reliably increased observers' performance (reduced guessing, increased report precision) as compared to neutral ones; invalid pre-cues had the opposite effect. Valid retro-cues also consistently improved performance (by reducing random guesses), even if the unexpected group suddenly became relevant (invalid-valid condition). Thus, feature-based attention can reshape priorities in VSTM protecting information that would otherwise be forgotten.

Psychological restoration can depend on stimulus-source attribution: A challenge for the evolutionary account?

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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.

Modeling stimulus variation in three common implicit attitude tasks.

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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.

Autoshaping with common and distinctive stimulus elements, compact and dispersed arrays1

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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

Thalamic neuron models encode stimulus information by burst-size modulation

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Daniel Henry Elijah

2015-09-01

Full Text Available Thalamic neurons have been long assumed to fire in tonic mode during perceptive states, and in burst mode during sleep and unconsciousness. However, recent evidence suggests that bursts may also be relevant in the encoding of sensory information. Here we explore the neural code of such thalamic bursts. In order to assess whether the burst code is generic or whether it depends on the detailed properties of each bursting neuron, we analyzed two neuron models incorporating different levels of biological detail. One of the models contained no information of the biophysical processes entailed in spike generation, and described neuron activity at a phenomenological level. The second model represented the evolution of the individual ionic conductances involved in spiking and bursting, and required a large number of parameters. We analyzed the models' input selectivity using reverse correlation methods and information theory. We found that n-spike bursts from both models transmit information by modulating their spike count in response to changes to instantaneous input features, such as slope, phase, amplitude, etc. The stimulus feature that is most efficiently encoded by bursts, however, need not coincide with one of such classical features. We therefore searched for the optimal feature among all those that could be expressed as a linear transformation of the time-dependent input current. We found that bursting neurons transmitted 6 times more information about such more general features. The relevant events in the stimulus were located in a time window spanning ~100 ms before and ~20 ms after burst onset. Most importantly, the neural code employed by the simple and the biologically realistic models was largely the same, implying that the simple thalamic neuron model contains the essential ingredients that account for the computational properties of the thalamic burst code. Thus, our results suggest the n-spike burst code is a general property of

Thalamic neuron models encode stimulus information by burst-size modulation.

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Elijah, Daniel H; Samengo, Inés; Montemurro, Marcelo A

2015-01-01

Thalamic neurons have been long assumed to fire in tonic mode during perceptive states, and in burst mode during sleep and unconsciousness. However, recent evidence suggests that bursts may also be relevant in the encoding of sensory information. Here, we explore the neural code of such thalamic bursts. In order to assess whether the burst code is generic or whether it depends on the detailed properties of each bursting neuron, we analyzed two neuron models incorporating different levels of biological detail. One of the models contained no information of the biophysical processes entailed in spike generation, and described neuron activity at a phenomenological level. The second model represented the evolution of the individual ionic conductances involved in spiking and bursting, and required a large number of parameters. We analyzed the models' input selectivity using reverse correlation methods and information theory. We found that n-spike bursts from both models transmit information by modulating their spike count in response to changes to instantaneous input features, such as slope, phase, amplitude, etc. The stimulus feature that is most efficiently encoded by bursts, however, need not coincide with one of such classical features. We therefore searched for the optimal feature among all those that could be expressed as a linear transformation of the time-dependent input current. We found that bursting neurons transmitted 6 times more information about such more general features. The relevant events in the stimulus were located in a time window spanning ~100 ms before and ~20 ms after burst onset. Most importantly, the neural code employed by the simple and the biologically realistic models was largely the same, implying that the simple thalamic neuron model contains the essential ingredients that account for the computational properties of the thalamic burst code. Thus, our results suggest the n-spike burst code is a general property of thalamic neurons.

Generalization of a tactile stimulus in horses.

Science.gov (United States)

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.

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.

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

OpenAIRE

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...

Can responses to basic non-numerical visual features explain neural numerosity responses?

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Harvey, Ben M; Dumoulin, Serge O

2017-04-01

Humans and many animals can distinguish between stimuli that differ in numerosity, the number of objects in a set. Human and macaque parietal lobes contain neurons that respond to changes in stimulus numerosity. However, basic non-numerical visual features can affect neural responses to and perception of numerosity, and visual features often co-vary with numerosity. Therefore, it is debated whether numerosity or co-varying low-level visual features underlie neural and behavioral responses to numerosity. To test the hypothesis that non-numerical visual features underlie neural numerosity responses in a human parietal numerosity map, we analyze responses to a group of numerosity stimulus configurations that have the same numerosity progression but vary considerably in their non-numerical visual features. Using ultra-high-field (7T) fMRI, we measure responses to these stimulus configurations in an area of posterior parietal cortex whose responses are believed to reflect numerosity-selective activity. We describe an fMRI analysis method to distinguish between alternative models of neural response functions, following a population receptive field (pRF) modeling approach. For each stimulus configuration, we first quantify the relationships between numerosity and several non-numerical visual features that have been proposed to underlie performance in numerosity discrimination tasks. We then determine how well responses to these non-numerical visual features predict the observed fMRI responses, and compare this to the predictions of responses to numerosity. We demonstrate that a numerosity response model predicts observed responses more accurately than models of responses to simple non-numerical visual features. As such, neural responses in cognitive processing need not reflect simpler properties of early sensory inputs. Copyright © 2017 Elsevier Inc. All rights reserved.

Feature-based attentional modulation increases with stimulus separation in divided-attention tasks.

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Sally, Sharon L; Vidnyánsky, Zoltán; Papathomas, Thomas V

2009-01-01

Attention modifies our visual experience by selecting certain aspects of a scene for further processing. It is therefore important to understand factors that govern the deployment of selective attention over the visual field. Both location and feature-specific mechanisms of attention have been identified and their modulatory effects can interact at a neural level (Treue and Martinez-Trujillo, 1999). The effects of spatial parameters on feature-based attentional modulation were examined for the feature dimensions of orientation, motion and color using three divided-attention tasks. Subjects performed concurrent discriminations of two briefly presented targets (Gabor patches) to the left and right of a central fixation point at eccentricities of +/-2.5 degrees , 5 degrees , 10 degrees and 15 degrees in the horizontal plane. Gabors were size-scaled to maintain consistent single-task performance across eccentricities. For all feature dimensions, the data show a linear increase in the attentional effects with target separation. In a control experiment, Gabors were presented on an isoeccentric viewing arc at 10 degrees and 15 degrees at the closest spatial separation (+/-2.5 degrees ) of the main experiment. Under these conditions, the effects of feature-based attentional effects were largely eliminated. Our results are consistent with the hypothesis that feature-based attention prioritizes the processing of attended features. Feature-based attentional mechanisms may have helped direct the attentional focus to the appropriate target locations at greater separations, whereas similar assistance may not have been necessary at closer target spacings. The results of the present study specify conditions under which dual-task performance benefits from sharing similar target features and may therefore help elucidate the processes by which feature-based attention operates.

The stimulus integration area for horizontal vergence.

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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.

Science.gov (United States)

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.

Automatic Samples Selection Using Histogram of Oriented Gradients (HOG Feature Distance

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Inzar Salfikar

2018-01-01

Full Text Available Finding victims at a disaster site is the primary goal of Search-and-Rescue (SAR operations. Many technologies created from research for searching disaster victims through aerial imaging. but, most of them are difficult to detect victims at tsunami disaster sites with victims and backgrounds which are look similar. This research collects post-tsunami aerial imaging data from the internet to builds dataset and model for detecting tsunami disaster victims. Datasets are built based on distance differences from features every sample using Histogram-of-Oriented-Gradient (HOG method. We use the longest distance to collect samples from photo to generate victim and non-victim samples. We claim steps to collect samples by measuring HOG feature distance from all samples. the longest distance between samples will take as a candidate to build the dataset, then classify victim (positives and non-victim (negatives samples manually. The dataset of tsunami disaster victims was re-analyzed using cross-validation Leave-One-Out (LOO with Support-Vector-Machine (SVM method. The experimental results show the performance of two test photos with 61.70% precision, 77.60% accuracy, 74.36% recall and f-measure 67.44% to distinguish victim (positives and non-victim (negatives.

Generalization of a tactile stimulus in horses.

OpenAIRE

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...

Emotional Picture and Word Processing: An fMRI Study on Effects of Stimulus Complexity

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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

Attention improves encoding of task-relevant features in the human visual cortex

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Jehee, Janneke F.M.; Brady, Devin K.; Tong, Frank

2011-01-01

When spatial attention is directed towards a particular stimulus, increased activity is commonly observed in corresponding locations of the visual cortex. Does this attentional increase in activity indicate improved processing of all features contained within the attended stimulus, or might spatial attention selectively enhance the features relevant to the observer’s task? We used fMRI decoding methods to measure the strength of orientation-selective activity patterns in the human visual cortex while subjects performed either an orientation or contrast discrimination task, involving one of two laterally presented gratings. Greater overall BOLD activation with spatial attention was observed in areas V1-V4 for both tasks. However, multivariate pattern analysis revealed that orientation-selective responses were enhanced by attention only when orientation was the task-relevant feature, and not when the grating’s contrast had to be attended. In a second experiment, observers discriminated the orientation or color of a specific lateral grating. Here, orientation-selective responses were enhanced in both tasks but color-selective responses were enhanced only when color was task-relevant. In both experiments, task-specific enhancement of feature-selective activity was not confined to the attended stimulus location, but instead spread to other locations in the visual field, suggesting the concurrent involvement of a global feature-based attentional mechanism. These results suggest that attention can be remarkably selective in its ability to enhance particular task-relevant features, and further reveal that increases in overall BOLD amplitude are not necessarily accompanied by improved processing of stimulus information. PMID:21632942

Conditioned [corrected] stimulus informativeness governs conditioned stimulus-unconditioned stimulus associability.

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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.

The Stimulus test stand

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

Abstract feature codes: The building blocks of the implicit learning system.

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Eberhardt, Katharina; Esser, Sarah; Haider, Hilde

2017-07-01

According to the Theory of Event Coding (TEC; Hommel, Müsseler, Aschersleben, & Prinz, 2001), action and perception are represented in a shared format in the cognitive system by means of feature codes. In implicit sequence learning research, it is still common to make a conceptual difference between independent motor and perceptual sequences. This supposedly independent learning takes place in encapsulated modules (Keele, Ivry, Mayr, Hazeltine, & Heuer 2003) that process information along single dimensions. These dimensions have remained underspecified so far. It is especially not clear whether stimulus and response characteristics are processed in separate modules. Here, we suggest that feature dimensions as they are described in the TEC should be viewed as the basic content of modules of implicit learning. This means that the modules process all stimulus and response information related to certain feature dimensions of the perceptual environment. In 3 experiments, we investigated by means of a serial reaction time task the nature of the basic units of implicit learning. As a test case, we used stimulus location sequence learning. The results show that a stimulus location sequence and a response location sequence cannot be learned without interference (Experiment 2) unless one of the sequences can be coded via an alternative, nonspatial dimension (Experiment 3). These results support the notion that spatial location is one module of the implicit learning system and, consequently, that there are no separate processing units for stimulus versus response locations. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

VARIASI STIMULUS DALAM PELATIHAN KEWIRAUSAHAAN STIMULUS VARIATION IN ENTREPRENEURSHIP TRAINING

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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.

Visual training improves perceptual grouping based on basic stimulus features.

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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.

Synaptic heterogeneity and stimulus-induced modulation of depression in central synapses.

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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.

Statistical methods for detecting differentially abundant features in clinical metagenomic samples.

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James Robert White

2009-04-01

Full Text Available Numerous studies are currently underway to characterize the microbial communities inhabiting our world. These studies aim to dramatically expand our understanding of the microbial biosphere and, more importantly, hope to reveal the secrets of the complex symbiotic relationship between us and our commensal bacterial microflora. An important prerequisite for such discoveries are computational tools that are able to rapidly and accurately compare large datasets generated from complex bacterial communities to identify features that distinguish them.We present a statistical method for comparing clinical metagenomic samples from two treatment populations on the basis of count data (e.g. as obtained through sequencing to detect differentially abundant features. Our method, Metastats, employs the false discovery rate to improve specificity in high-complexity environments, and separately handles sparsely-sampled features using Fisher's exact test. Under a variety of simulations, we show that Metastats performs well compared to previously used methods, and significantly outperforms other methods for features with sparse counts. We demonstrate the utility of our method on several datasets including a 16S rRNA survey of obese and lean human gut microbiomes, COG functional profiles of infant and mature gut microbiomes, and bacterial and viral metabolic subsystem data inferred from random sequencing of 85 metagenomes. The application of our method to the obesity dataset reveals differences between obese and lean subjects not reported in the original study. For the COG and subsystem datasets, we provide the first statistically rigorous assessment of the differences between these populations. The methods described in this paper are the first to address clinical metagenomic datasets comprising samples from multiple subjects. Our methods are robust across datasets of varied complexity and sampling level. While designed for metagenomic applications, our software

Dissociating neural variability related to stimulus quality and response times in perceptual decision-making.

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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.

Controlling Relations in Baseline Conditional Discriminations as Determinants of Stimulus Equivalence

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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…

Stimulus Probability Effects in Absolute Identification

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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…

Recognizing famous voices: influence of stimulus duration and different types of retrieval cues.

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Schweinberger, S R; Herholz, A; Sommer, W

1997-04-01

The current investigation measured the effects of increasing stimulus duration on listeners' ability to recognize famous voices. In addition, the investigation studied the influence of different types of cues on the naming of voices that could not be named before. Participants were presented with samples of famous and unfamiliar voices and were asked to decide whether or not the samples were spoken by a famous person. The duration of each sample increased in seven steps from 0.25 s up to a maximum of 2 s. Voice recognition improvements with stimulus duration were with a growth function. Gains were most rapid within the first second and less pronounced thereafter. When participants were unable to name a famous voice, they were cued with either a second voice sample, the occupation, or the initials of the celebrity. Initials were most effective in eliciting the name only when semantic information about the speaker had been accessed prior to cue presentation. Paralleling previous research on face naming, this may indicate that voice naming is contingent on previous activation of person-specific semantic information.

Effect of feature-selective attention on neuronal responses in macaque area MT

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Chen, X.; Hoffmann, K.-P.; Albright, T. D.

2012-01-01

Attention influences visual processing in striate and extrastriate cortex, which has been extensively studied for spatial-, object-, and feature-based attention. Most studies exploring neural signatures of feature-based attention have trained animals to attend to an object identified by a certain feature and ignore objects/displays identified by a different feature. Little is known about the effects of feature-selective attention, where subjects attend to one stimulus feature domain (e.g., color) of an object while features from different domains (e.g., direction of motion) of the same object are ignored. To study this type of feature-selective attention in area MT in the middle temporal sulcus, we trained macaque monkeys to either attend to and report the direction of motion of a moving sine wave grating (a feature for which MT neurons display strong selectivity) or attend to and report its color (a feature for which MT neurons have very limited selectivity). We hypothesized that neurons would upregulate their firing rate during attend-direction conditions compared with attend-color conditions. We found that feature-selective attention significantly affected 22% of MT neurons. Contrary to our hypothesis, these neurons did not necessarily increase firing rate when animals attended to direction of motion but fell into one of two classes. In one class, attention to color increased the gain of stimulus-induced responses compared with attend-direction conditions. The other class displayed the opposite effects. Feature-selective activity modulations occurred earlier in neurons modulated by attention to color compared with neurons modulated by attention to motion direction. Thus feature-selective attention influences neuronal processing in macaque area MT but often exhibited a mismatch between the preferred stimulus dimension (direction of motion) and the preferred attention dimension (attention to color). PMID:22170961

Emotion recognition abilities across stimulus modalities in schizophrenia and the role of visual attention.

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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.

Measuring Biometric Sample Quality in terms of Biometric Feature Information in Iris Images

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R. Youmaran

2012-01-01

Full Text Available This paper develops an approach to measure the information content in a biometric feature representation of iris images. In this context, the biometric feature information is calculated using the relative entropy between the intraclass and interclass feature distributions. The collected data is regularized using a Gaussian model of the feature covariances in order to practically measure the biometric information with limited data samples. An example of this method is shown for iris templates processed using Principal-Component Analysis- (PCA- and Independent-Component Analysis- (ICA- based feature decomposition schemes. From this, the biometric feature information is calculated to be approximately 278 bits for PCA and 288 bits for ICA iris features using Masek's iris recognition scheme. This value approximately matches previous estimates of iris information content.

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.

Locus of Control, Self-esteem, Stimulus Appraisal, and Depressive Symptoms in Children

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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)

Hierarchical Neural Representation of Dreamed Objects Revealed by Brain Decoding with Deep Neural Network Features.

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Horikawa, Tomoyasu; Kamitani, Yukiyasu

2017-01-01

Dreaming is generally thought to be generated by spontaneous brain activity during sleep with patterns common to waking experience. This view is supported by a recent study demonstrating that dreamed objects can be predicted from brain activity during sleep using statistical decoders trained with stimulus-induced brain activity. However, it remains unclear whether and how visual image features associated with dreamed objects are represented in the brain. In this study, we used a deep neural network (DNN) model for object recognition as a proxy for hierarchical visual feature representation, and DNN features for dreamed objects were analyzed with brain decoding of fMRI data collected during dreaming. The decoders were first trained with stimulus-induced brain activity labeled with the feature values of the stimulus image from multiple DNN layers. The decoders were then used to decode DNN features from the dream fMRI data, and the decoded features were compared with the averaged features of each object category calculated from a large-scale image database. We found that the feature values decoded from the dream fMRI data positively correlated with those associated with dreamed object categories at mid- to high-level DNN layers. Using the decoded features, the dreamed object category could be identified at above-chance levels by matching them to the averaged features for candidate categories. The results suggest that dreaming recruits hierarchical visual feature representations associated with objects, which may support phenomenal aspects of dream experience.

Use of a Differential Observing Response to Expand Restricted Stimulus Control

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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…

Feature Selection Methods for Zero-Shot Learning of Neural Activity

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Carlos A. Caceres

2017-06-01

Full Text Available Dimensionality poses a serious challenge when making predictions from human neuroimaging data. Across imaging modalities, large pools of potential neural features (e.g., responses from particular voxels, electrodes, and temporal windows have to be related to typically limited sets of stimuli and samples. In recent years, zero-shot prediction models have been introduced for mapping between neural signals and semantic attributes, which allows for classification of stimulus classes not explicitly included in the training set. While choices about feature selection can have a substantial impact when closed-set accuracy, open-set robustness, and runtime are competing design objectives, no systematic study of feature selection for these models has been reported. Instead, a relatively straightforward feature stability approach has been adopted and successfully applied across models and imaging modalities. To characterize the tradeoffs in feature selection for zero-shot learning, we compared correlation-based stability to several other feature selection techniques on comparable data sets from two distinct imaging modalities: functional Magnetic Resonance Imaging and Electrocorticography. While most of the feature selection methods resulted in similar zero-shot prediction accuracies and spatial/spectral patterns of selected features, there was one exception; A novel feature/attribute correlation approach was able to achieve those accuracies with far fewer features, suggesting the potential for simpler prediction models that yield high zero-shot classification accuracy.

Dynamics and stimulus-dependence of pacemaker control during behavioral modulations in the weakly electric fish, Apteronotus.

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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.

Intranasal localizability of odorants: influence of stimulus volume.

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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.

Associative cueing of attention through implicit feature-location binding.

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Girardi, Giovanna; Nico, Daniele

2017-09-01

In order to assess associative learning between two task-irrelevant features in cueing spatial attention, we devised a task in which participants have to make an identity comparison between two sequential visual stimuli. Unbeknownst to them, location of the second stimulus could be predicted by the colour of the first or a concurrent sound. Albeit unnecessary to perform the identity-matching judgment the predictive features thus provided an arbitrary association favouring the spatial anticipation of the second stimulus. A significant advantage was found with faster responses at predicted compared to non-predicted locations. Results clearly demonstrated an associative cueing of attention via a second-order arbitrary feature/location association but with a substantial discrepancy depending on the sensory modality of the predictive feature. With colour as predictive feature, significant advantages emerged only after the completion of three blocks of trials. On the contrary, sound affected responses from the first block of trials and significant advantages were manifest from the beginning of the second. The possible mechanisms underlying the associative cueing of attention in both conditions are discussed. Copyright © 2017 Elsevier B.V. All rights reserved.

Stimulus-specific variability in color working memory with delayed estimation.

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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.

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

The Temporal Dynamics of Feature Integration for Color, form, and Motion

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KS Pilz

2012-07-01

Full Text Available When two similar visual stimuli are presented in rapid succession, only their fused image is perceived, without having conscious access to the single stimuli. Such feature fusion occurs both for color (eg, Efron1973 and form (eg, Scharnowski et al 2007. For verniers, the fusion process lasts for more than 400 ms, as has been shown using TMS (Scharnowski et al 2009. In three experiments, we used light masks to investigate the time course of feature fusion for color, form, and motion. In experiment one, two verniers were presented in rapid succession with opposite offset directions. Subjects had to indicate the offset direction of the vernier. In a second experiment, a red and a green disk were presented in rapid succession, and subjects had to indicate whether the fused, yellow disk appeared rather than red or green. In a third experiment, three frames of random dots were presented successively. The first two frames created a percept of apparent motion to the upper right; and the last two frames, one to the upper left or vice versa. Subjects had to indicate the direction of motion. All stimuli were presented foveally. In all three experiments, we first balanced performance so that neither the first nor the second stimulus dominated the fused percept. In a second step, a light mask was presented either before, during, or after stimulus presentation. Depending on presentation time, the light masks modulated the fusion process so that either the first or the second stimulus dominated the percept. Our results show that unconscious feature fusion lasts more than five times longer than the actual stimulus duration, which indicates that individual features are stored for a substantial amount of time before they are integrated.

[Microcomputer control of a LED stimulus display device].

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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.

Unconscious analyses of visual scenes based on feature conjunctions.

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Tachibana, Ryosuke; Noguchi, Yasuki

2015-06-01

To efficiently process a cluttered scene, the visual system analyzes statistical properties or regularities of visual elements embedded in the scene. It is controversial, however, whether those scene analyses could also work for stimuli unconsciously perceived. Here we show that our brain performs the unconscious scene analyses not only using a single featural cue (e.g., orientation) but also based on conjunctions of multiple visual features (e.g., combinations of color and orientation information). Subjects foveally viewed a stimulus array (duration: 50 ms) where 4 types of bars (red-horizontal, red-vertical, green-horizontal, and green-vertical) were intermixed. Although a conscious perception of those bars was inhibited by a subsequent mask stimulus, the brain correctly analyzed the information about color, orientation, and color-orientation conjunctions of those invisible bars. The information of those features was then used for the unconscious configuration analysis (statistical processing) of the central bars, which induced a perceptual bias and illusory feature binding in visible stimuli at peripheral locations. While statistical analyses and feature binding are normally 2 key functions of the visual system to construct coherent percepts of visual scenes, our results show that a high-level analysis combining those 2 functions is correctly performed by unconscious computations in the brain. (c) 2015 APA, all rights reserved).

Feature-based attention: it is all bottom-up priming.

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Theeuwes, Jan

2013-10-19

Feature-based attention (FBA) enhances the representation of image characteristics throughout the visual field, a mechanism that is particularly useful when searching for a specific stimulus feature. Even though most theories of visual search implicitly or explicitly assume that FBA is under top-down control, we argue that the role of top-down processing in FBA may be limited. Our review of the literature indicates that all behavioural and neuro-imaging studies investigating FBA suffer from the shortcoming that they cannot rule out an effect of priming. The mere attending to a feature enhances the mandatory processing of that feature across the visual field, an effect that is likely to occur in an automatic, bottom-up way. Studies that have investigated the feasibility of FBA by means of cueing paradigms suggest that the role of top-down processing in FBA is limited (e.g. prepare for red). Instead, the actual processing of the stimulus is needed to cause the mandatory tuning of responses throughout the visual field. We conclude that it is likely that all FBA effects reported previously are the result of bottom-up priming.

Visual awareness suppression by pre-stimulus brain stimulation; a neural effect.

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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.

Developing a Projective Drawing Test: Experiences with the Face Stimulus Assessment (FSA).

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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…

Temporal integration: intentional sound discrimination does not modulate stimulus-driven processes in auditory event synthesis.

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Sussman, Elyse; Winkler, István; Kreuzer, Judith; Saher, Marieke; Näätänen, Risto; Ritter, Walter

2002-12-01

Our previous study showed that the auditory context could influence whether two successive acoustic changes occurring within the temporal integration window (approximately 200ms) were pre-attentively encoded as a single auditory event or as two discrete events (Cogn Brain Res 12 (2001) 431). The aim of the current study was to assess whether top-down processes could influence the stimulus-driven processes in determining what constitutes an auditory event. Electroencepholagram (EEG) was recorded from 11 scalp electrodes to frequently occurring standard and infrequently occurring deviant sounds. Within the stimulus blocks, deviants either occurred only in pairs (successive feature changes) or both singly and in pairs. Event-related potential indices of change and target detection, the mismatch negativity (MMN) and the N2b component, respectively, were compared with the simultaneously measured performance in discriminating the deviants. Even though subjects could voluntarily distinguish the two successive auditory feature changes from each other, which was also indicated by the elicitation of the N2b target-detection response, top-down processes did not modify the event organization reflected by the MMN response. Top-down processes can extract elemental auditory information from a single integrated acoustic event, but the extraction occurs at a later processing stage than the one whose outcome is indexed by MMN. Initial processes of auditory event-formation are fully governed by the context within which the sounds occur. Perception of the deviants as two separate sound events (the top-down effects) did not change the initial neural representation of the same deviants as one event (indexed by the MMN), without a corresponding change in the stimulus-driven sound organization.

Alterations to multisensory and unisensory integration by stimulus competition.

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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.

Non-retinotopic feature processing in the absence of retinotopic spatial layout and the construction of perceptual space from motion.

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Ağaoğlu, Mehmet N; Herzog, Michael H; Oğmen, Haluk

2012-10-15

The spatial representation of a visual scene in the early visual system is well known. The optics of the eye map the three-dimensional environment onto two-dimensional images on the retina. These retinotopic representations are preserved in the early visual system. Retinotopic representations and processing are among the most prevalent concepts in visual neuroscience. However, it has long been known that a retinotopic representation of the stimulus is neither sufficient nor necessary for perception. Saccadic Stimulus Presentation Paradigm and the Ternus-Pikler displays have been used to investigate non-retinotopic processes with and without eye movements, respectively. However, neither of these paradigms eliminates the retinotopic representation of the spatial layout of the stimulus. Here, we investigated how stimulus features are processed in the absence of a retinotopic layout and in the presence of retinotopic conflict. We used anorthoscopic viewing (slit viewing) and pitted a retinotopic feature-processing hypothesis against a non-retinotopic feature-processing hypothesis. Our results support the predictions of the non-retinotopic feature-processing hypothesis and demonstrate the ability of the visual system to operate non-retinotopically at a fine feature processing level in the absence of a retinotopic spatial layout. Our results suggest that perceptual space is actively constructed from the perceptual dimension of motion. The implications of these findings for normal ecological viewing conditions are discussed. 2012 Elsevier Ltd. All rights reserved

Stimulus size dependence of hue changes induced by chromatic surrounds.

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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.

Coding space-time stimulus dynamics in auditory brain maps

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Yunyan eWang

2014-04-01

Full Text Available Sensory maps are often distorted representations of the environment, where ethologically-important ranges are magnified. The implication of a biased representation extends beyond increased acuity for having more neurons dedicated to a certain range. Because neurons are functionally interconnected, non-uniform representations influence the processing of high-order features that rely on comparison across areas of the map. Among these features are time-dependent changes of the auditory scene generated by moving objects. How sensory representation affects high order processing can be approached in the map of auditory space of the owl’s midbrain, where locations in the front are over-represented. In this map, neurons are selective not only to location but also to location over time. The tuning to space over time leads to direction selectivity, which is also topographically organized. Across the population, neurons tuned to peripheral space are more selective to sounds moving into the front. The distribution of direction selectivity can be explained by spatial and temporal integration on the non-uniform map of space. Thus, the representation of space can induce biased computation of a second-order stimulus feature. This phenomenon is likely observed in other sensory maps and may be relevant for behavior.

Utility-based early modulation of processing distracting stimulus information.

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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.

Dendrites Enable a Robust Mechanism for Neuronal Stimulus Selectivity.

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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.

Strategic allocation of attention reduces temporally predictable stimulus conflict

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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

Did you hear that? The role of stimulus similarity and uncertainty in auditory change deafness

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Kelly eDickerson

2014-10-01

Full Text Available Change deafness, the auditory analog to change blindness, occurs when salient and behaviorally relevant changes to sound sources are missed. Missing significant changes in the environment can have serious consequences, however, this effect, has remained little more than a lab phenomenon and a party trick. It is only recently that researchers have begun to explore the nature of these profound errors in change perception. Despite a wealth of examples of the change blindness phenomenon, work on change deafness remains fairly limited. The purpose of the current paper is to review the state of the literature on change deafness and propose an explanation of change deafness that relies on factors related to stimulus information rather than attentional or memory limits. To achieve this, work on across several auditory research domains, including environmental sound classification, informational masking and change deafness are synthesized to present a unified perspective on the perception of change errors in complex, dynamic sound environments. We hope to extend previous research by describing how it may be possible to predict specific patters of change perception errors based on varying degrees of similarity in stimulus features and uncertainty about which stimuli and features are important for a given perceptual decision.

Nanoscale theranostics for physical stimulus-responsive cancer therapies.

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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.

In support of a distinction between voluntary and stimulus-driven control: A review of the literature on proportion congruent effects

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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.

Role of amygdala central nucleus in feature negative discriminations

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Holland, Peter C.

2012-01-01

Consistent with a popular theory of associative learning, the Pearce-Hall (1980) model, the surprising omission of expected events enhances cue associability (the ease with which a cue may enter into new associations), across a wide variety of behavioral training procedures. Furthermore, previous experiments from this laboratory showed that these enhancements are absent in rats with impaired function of the amygdala central nucleus (CeA). A notable exception to these assertions is found in feature negative (FN) discrimination learning, in which a “target” stimulus is reinforced when it is presented alone but nonreinforced when it is presented in compound with another, “feature” stimulus. According to the Pearce-Hall model, reinforcer omission on compound trials should enhance the associability of the feature relative to control training conditions. However, prior experiments have shown no evidence that CeA lesions affect FN discrimination learning. Here we explored this apparent contradiction by evaluating the hypothesis that the surprising omission of an event confers enhanced associability on a cue only if that cue itself generates the disconfirmed prediction. Thus, in a FN discrimination, the surprising omission of the reinforcer on compound trials would enhance the associability of the target stimulus but not that of the feature. Our data confirmed this hypothesis, and showed this enhancement to depend on intact CeA function, as in other procedures. The results are consistent with modern reformulations of both cue and reward processing theories that assign roles for both individual and aggregate error terms in associative learning. PMID:22889308

StimDuino: an Arduino-based electrophysiological stimulus isolator.

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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.

Stream specificity and asymmetries in feature binding and content-addressable access in visual encoding and memory.

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Huynh, Duong L; Tripathy, Srimant P; Bedell, Harold E; Ögmen, Haluk

2015-01-01

Human memory is content addressable-i.e., contents of the memory can be accessed using partial information about the bound features of a stored item. In this study, we used a cross-feature cuing technique to examine how the human visual system encodes, binds, and retains information about multiple stimulus features within a set of moving objects. We sought to characterize the roles of three different features (position, color, and direction of motion, the latter two of which are processed preferentially within the ventral and dorsal visual streams, respectively) in the construction and maintenance of object representations. We investigated the extent to which these features are bound together across the following processing stages: during stimulus encoding, sensory (iconic) memory, and visual short-term memory. Whereas all features examined here can serve as cues for addressing content, their effectiveness shows asymmetries and varies according to cue-report pairings and the stage of information processing and storage. Position-based indexing theories predict that position should be more effective as a cue compared to other features. While we found a privileged role for position as a cue at the stimulus-encoding stage, position was not the privileged cue at the sensory and visual short-term memory stages. Instead, the pattern that emerged from our findings is one that mirrors the parallel processing streams in the visual system. This stream-specific binding and cuing effectiveness manifests itself in all three stages of information processing examined here. Finally, we find that the Leaky Flask model proposed in our previous study is applicable to all three features.

Positive and negative affect produce opposing task-irrelevant stimulus preexposure effects.

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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.

Feature-selective attention in healthy old age: a selective decline in selective attention?

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Quigley, Cliodhna; Müller, Matthias M

2014-02-12

Deficient selection against irrelevant information has been proposed to underlie age-related cognitive decline. We recently reported evidence for maintained early sensory selection when older and younger adults used spatial selective attention to perform a challenging task. Here we explored age-related differences when spatial selection is not possible and feature-selective attention must be deployed. We additionally compared the integrity of feedforward processing by exploiting the well established phenomenon of suppression of visual cortical responses attributable to interstimulus competition. Electroencephalogram was measured while older and younger human adults responded to brief occurrences of coherent motion in an attended stimulus composed of randomly moving, orientation-defined, flickering bars. Attention was directed to horizontal or vertical bars by a pretrial cue, after which two orthogonally oriented, overlapping stimuli or a single stimulus were presented. Horizontal and vertical bars flickered at different frequencies and thereby elicited separable steady-state visual-evoked potentials, which were used to examine the effect of feature-based selection and the competitive influence of a second stimulus on ongoing visual processing. Age differences were found in feature-selective attentional modulation of visual responses: older adults did not show consistent modulation of magnitude or phase. In contrast, the suppressive effect of a second stimulus was robust and comparable in magnitude across age groups, suggesting that bottom-up processing of the current stimuli is essentially unchanged in healthy old age. Thus, it seems that visual processing per se is unchanged, but top-down attentional control is compromised in older adults when space cannot be used to guide selection.

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.

Effects of Multimodal Presentation and Stimulus Familiarity on Auditory and Visual Processing

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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

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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

High-Intensity Exercise as a Dishabituating Stimulus Restores Counterregulatory Responses in Recurrently Hypoglycemic Rodents.

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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.

Psilocybin-induced stimulus control in the rat.

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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.

Attention and alcohol cues: a role for medial parietal cortex and shifting away from alcohol features?

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Thomas Edward Gladwin

2013-12-01

Full Text Available Attention plays a central role in theories of alcohol dependence; however, its precise role in alcohol-related biases is not yet clear. In the current study, social drinkers performed a spatial cueing task designed to evoke conflict between automatic processes due to incentive salience and control exerted to follow task-related goals. Such conflict is a potentially important task feature from the perspective of dual-process models of addiction. Subjects received instructions either to direct their attention towards pictures of alcoholic beverages, and away from non-alcohol beverages; or to direct their attention towards pictures of non-alcoholic beverages, and away from alcohol beverages. A probe stimulus was likely to appear at the attended location, so that both spatial and non-spatial interference was possible. Activation in medial parietal cortex was found during Approach Alcohol versus Avoid Alcohol blocks. This region is associated with the, possibly automatic, shifting of attention between stimulus features, suggesting that subjects may have shifted attention away from certain features of alcoholic cues when attention had to be directed towards an upcoming stimulus at their location. Further, activation in voxels close to this region was negatively correlated with riskier drinking behavior. A tentative interpretation of the results is that risky drinking may be associated with a reduced tendency to shift attention away from potentially distracting task-irrelevant alcohol cues. The results suggest novel hypotheses and directions for future study, in particular towards the potential therapeutic use of training the ability to shifting attention away from alcohol-related stimulus features.

Psilocybin-induced stimulus control in the rat

OpenAIRE

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...

Auditory proactive interference in monkeys: the roles of stimulus set size and intertrial interval.

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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.

Learning to fear a second-order stimulus following vicarious learning.

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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

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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.

Optimal spatiotemporal representation of multichannel EEG for recognition of brain states associated with distinct visual stimulus

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Hramov, Alexander; Musatov, Vyacheslav Yu.; Runnova, Anastasija E.; Efremova, Tatiana Yu.; Koronovskii, Alexey A.; Pisarchik, Alexander N.

2018-04-01

In the paper we propose an approach based on artificial neural networks for recognition of different human brain states associated with distinct visual stimulus. Based on the developed numerical technique and the analysis of obtained experimental multichannel EEG data, we optimize the spatiotemporal representation of multichannel EEG to provide close to 97% accuracy in recognition of the EEG brain states during visual perception. Different interpretations of an ambiguous image produce different oscillatory patterns in the human EEG with similar features for every interpretation. Since these features are inherent to all subjects, a single artificial network can classify with high quality the associated brain states of other subjects.

Dissociating Goal-Directed and Stimulus-Driven Determinants in Attentional Capture

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Louis K. H. Chan

2011-05-01

Full Text Available Although attentional capture is now a commonplace finding, the exact roles played by goal-directed and stimulus-driven determents remain elusive. An unsettled issue is on the relative contribution of attentional set and visual saliency. In the present study, we investigated this issue by mixing color and orientation search trials, so that distractors of either feature dimension fell into the current attentional set. In our test, color features were more salient. As a result, in orientation search, whereas a color distractor produced huge capture (109 ms, an orientation distractor produced moderate capture (50 ms. With color targets, distractors were not interfering. On one hand, these results reflect that relative salience of the target and the distractor is critical for producing capture; on the other hand, a huge capture size associated with a nontarget dimension feature is novel. Similar previous measurements, but without matching the attentional set, consistently report attentional capture of only 20-30 ms. This comparison shows the role played by attentional set. Taken together, we suggest that visual saliency determines search order, and sets the platform for capture. However, attentional dwell time on the distractor is determined by how much it matches the current attentional set, and in turn explains the capture size.

Exact Analysis of Intrinsic Qualitative Features of Phosphorelays using Mathematical Models

DEFF Research Database (Denmark)

Knudsen, Michael; Feliu, Elisenda; Wiuf, Carsten Henrik

2012-01-01

stable steady-state. Furthermore, we derive explicit functions relating stimulus to the response in any layer of a phosphorelay and show that a limited degree of ultrasensitivity in the bottom layer of a phosphorelay is an intrinsic feature which does not depend on any reaction rates or substrate amounts....... On the other hand, we show how adjusting reaction rates and substrate amounts may lead to higher degrees of ultrasensitivity in intermediate layers. The explicit formulas also enable us to prove how the response changes with alterations in stimulus, kinetic parameters, and substrate amounts. Aside from...

Evaluation of a Multiple-Stimulus Presentation Format for Assessing Reinforcer Preferences.

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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…

Sequential Modulations in a Combined Horizontal and Vertical Simon Task: Is There ERP Evidence for Feature Integration Effects?

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Hoppe, Katharina; Küper, Kristina; Wascher, Edmund

2017-01-01

In the Simon task, participants respond faster when the task-irrelevant stimulus position and the response position are corresponding, for example on the same side, compared to when they have a non-corresponding relation. Interestingly, this Simon effect is reduced after non-corresponding trials. Such sequential effects can be explained in terms of a more focused processing of the relevant stimulus dimension due to increased cognitive control, which transfers from the previous non-corresponding trial (conflict adaptation effects). Alternatively, sequential modulations of the Simon effect can also be due to the degree of trial-to-trial repetitions and alternations of task features, which is confounded with the correspondence sequence (feature integration effects). In the present study, we used a spatially two-dimensional Simon task with vertical response keys to examine the contribution of adaptive cognitive control and feature integration processes to the sequential modulation of the Simon effect. The two-dimensional Simon task creates correspondences in the vertical as well as in the horizontal dimension. A trial-by-trial alternation of the spatial dimension, for example from a vertical to a horizontal stimulus presentation, generates a subset containing no complete repetitions of task features, but only complete alternations and partial repetitions, which are equally distributed over all correspondence sequences. In line with the assumed feature integration effects, we found sequential modulations of the Simon effect only when the spatial dimension repeated. At least for the horizontal dimension, this pattern was confirmed by the parietal P3b, an event-related potential that is assumed to reflect stimulus-response link processes. Contrary to conflict adaptation effects, cognitive control, measured by the fronto-central N2 component of the EEG, was not sequentially modulated. Overall, our data provide behavioral as well as electrophysiological evidence for feature

Pre-stimulus thalamic theta power predicts human memory formation.

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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

OpenAIRE

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...

Associative symmetry and stimulus-class formation by pigeons: the role of non-reinforced baseline relations.

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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.

Video-task assessment of learning and memory in Macaques (Macaca mulatta) - Effects of stimulus movement on performance

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Washburn, David A.; Hopkins, William D.; Rumbaugh, Duane M.

1989-01-01

Effects of stimulus movement on learning, transfer, matching, and short-term memory performance were assessed with 2 monkeys using a video-task paradigm in which the animals responded to computer-generated images by manipulating a joystick. Performance on tests of learning set, transfer index, matching to sample, and delayed matching to sample in the video-task paradigm was comparable to that obtained in previous investigations using the Wisconsin General Testing Apparatus. Additionally, learning, transfer, and matching were reliably and significantly better when the stimuli or discriminanda moved than when the stimuli were stationary. External manipulations such as stimulus movement may increase attention to the demands of a task, which in turn should increase the efficiency of learning. These findings have implications for the investigation of learning in other populations, as well as for the application of the video-task paradigm to comparative study.

Impact of stimulus uncanniness on speeded response

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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.

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

Learning to fear a second-order stimulus following vicarious learning

OpenAIRE

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...

The influence of spontaneous activity on stimulus processing in primary visual cortex.

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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.

Fixing the stimulus-as-fixed-effect fallacy in task fMRI [version 2; referees: 1 approved, 2 approved with reservations

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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.

Motormouth: Mere Exposure Depends on Stimulus-Specific Motor Simulations

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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…

Discriminative learning of receptive fields from responses to non-Gaussian stimulus ensembles.

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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

Noradrenergic modulation of neural erotic stimulus perception.

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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

The Correlation between Obsessive Compulsive Features and Dimensions of Pathological Eating Attitudes in Non-clinical Samples

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Ali Mohammadzadeh

2017-01-01

Full Text Available Background and Objectives: Obsessive compulsive symptoms are prevalent in individuals with eating disorders at clinical level. The purpose of this study was to investigate the correlation between obsessive compulsive features and pathological eating attitudes. Methods: This research is a correlational study. A sample of 790 university students were selected using stratified random sampling method and investigated by Obsessive Compulsive Inventory-Revised (OCI-R, and Eating Attitudes Test (EAT-26 questionnaires. Data were analyzed using multivariate regression analysis. Results: There were a correlation between obsessive-compulsive features and pathological eating attitudes (p<0.001, r=0.38, The results showed that obsessive-compulsive features can predict 15% of pathological eating attitudes (p<0.001, r2=0.15. Conclusion: The identified correlation is possibly related to common components between obsessive compulsive and eating disorders.

Acetylcholine release in the hippocampus during the operant conditioned reflex and the footshock stimulus in rats.

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Dong, Yu; Mao, Jianjun; Shangguan, Dihua; Zhao, Rui; Liu, Guoquan

2004-10-14

The activity of the septo-hippocampal cholinergic pathway was investigated by measuring changes in the extracellular acetylcholine (ACh) levels in the hippocampus, by means of microdialysis, during the operant conditioned reflex and the repeated footshock stimulus. Microdialysis samplings were conducted in a Skinner box where lights were delivered as conditioned stimuli (CS) paired with footshocks as unconditioned stimuli (US). Two groups of rats were used. Extracellular ACh and choline (Ch) in samples collected at 6min intervals were assessed by high-performance liquid chromatography with electrochemical detection. The elevation of hippocampus ACh was observed in the two experimental groups. The increase in ACh during aversive stimulus (footshock) was significantly larger and was probably related to the number of footshocks. There might be moderate increase in the hippocampal ACh release during the retrieval of information. The concentration of choline showed no significant fluctuation in the two groups during the whole process. This experiment explored in more detail hippocampal cholinergic activity in relation to the two different procedures.

Does air gas aesthesiometry generate a true mechanical stimulus for corneal sensitivity measurement?

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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.

Automatic detection of frequency changes depends on auditory stimulus intensity.

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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.

Single-subject withdrawal designs in delayed matching-to-sample procedures

OpenAIRE

Eilifsen, Christoffer; Arntzen, Erik

2011-01-01

In most studies of delayed matching-to-sample (DMTS) and stimulus equivalence, the delay has remained fixed throughout a single experimental condition. We wanted to expand on the DMTS and stimulus equivalence literature by examining the effects of using titrating delays with different starting points during the establishment of conditional discriminations prerequisite for stimulus equivalence. In Experiment 1, a variation of a single-subject withdrawal design was used. Ten adults were exposed...

Retrospective Attention Interacts with Stimulus Strength to Shape Working Memory Performance.

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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.

Sex and the stimulus-movement effect: Differences in acquisition of autoshaped responding in cynomolgus monkeys.

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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.

Sexual Orientation and Borderline Personality Disorder Features in a Community Sample of Adolescents.

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Reuter, Tyson R; Sharp, Carla; Kalpakci, Allison H; Choi, Hye J; Temple, Jeff R

2016-10-01

Empirical literature demonstrates that sexual minorities are at an increased risk of developing psychopathology, including borderline personality disorder (BPD). The specific link between sexual orientation and BPD has received significantly less attention in youth, and it remains unclear what drives this relation. Given that there are higher rates of psychopathology in both sexual minorities and individuals with BPD, the present study aimed to determine if sexual orientation uniquely contributes to borderline personality pathology, controlling for other psychopathology. An ethnically diverse sample of 835 adolescents completed self-report measures of borderline features, depression, anxiety, and sexual orientation. Sexual minorities scored higher on borderline features compared to heterosexual adolescents. When controlling for depression and anxiety, sexual orientation remained significantly associated with borderline features. The relation between sexual orientation and BPD cannot fully be explained by other psychopathology. Future research is necessary to understand potential mechanisms underlying this relation.

Mechanisms underlying effects of approach-avoidance training on stimulus evaluation.

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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).

Feature-selective Attention in Frontoparietal Cortex: Multivoxel Codes Adjust to Prioritize Task-relevant Information.

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Jackson, Jade; Rich, Anina N; Williams, Mark A; Woolgar, Alexandra

2017-02-01

Human cognition is characterized by astounding flexibility, enabling us to select appropriate information according to the objectives of our current task. A circuit of frontal and parietal brain regions, often referred to as the frontoparietal attention network or multiple-demand (MD) regions, are believed to play a fundamental role in this flexibility. There is evidence that these regions dynamically adjust their responses to selectively process information that is currently relevant for behavior, as proposed by the "adaptive coding hypothesis" [Duncan, J. An adaptive coding model of neural function in prefrontal cortex. Nature Reviews Neuroscience, 2, 820-829, 2001]. Could this provide a neural mechanism for feature-selective attention, the process by which we preferentially process one feature of a stimulus over another? We used multivariate pattern analysis of fMRI data during a perceptually challenging categorization task to investigate whether the representation of visual object features in the MD regions flexibly adjusts according to task relevance. Participants were trained to categorize visually similar novel objects along two orthogonal stimulus dimensions (length/orientation) and performed short alternating blocks in which only one of these dimensions was relevant. We found that multivoxel patterns of activation in the MD regions encoded the task-relevant distinctions more strongly than the task-irrelevant distinctions: The MD regions discriminated between stimuli of different lengths when length was relevant and between the same objects according to orientation when orientation was relevant. The data suggest a flexible neural system that adjusts its representation of visual objects to preferentially encode stimulus features that are currently relevant for behavior, providing a neural mechanism for feature-selective attention.

A Fundamental Study on Influence of Concurrently Presented Visual Stimulus Upon Loudness Perception

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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.

Electrophysiological Correlates of Changes in Reaction Time Based on Stimulus Intensity

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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

Retrospective Attention Interacts with Stimulus Strength to Shape Working Memory Performance.

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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.

Stimulus control: Part I

OpenAIRE

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.

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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

Energy Technology Data Exchange (ETDEWEB)

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.

Predictive features of persistent activity emergence in regular spiking and intrinsic bursting model neurons.

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Kyriaki Sidiropoulou

Full Text Available Proper functioning of working memory involves the expression of stimulus-selective persistent activity in pyramidal neurons of the prefrontal cortex (PFC, which refers to neural activity that persists for seconds beyond the end of the stimulus. The mechanisms which PFC pyramidal neurons use to discriminate between preferred vs. neutral inputs at the cellular level are largely unknown. Moreover, the presence of pyramidal cell subtypes with different firing patterns, such as regular spiking and intrinsic bursting, raises the question as to what their distinct role might be in persistent firing in the PFC. Here, we use a compartmental modeling approach to search for discriminatory features in the properties of incoming stimuli to a PFC pyramidal neuron and/or its response that signal which of these stimuli will result in persistent activity emergence. Furthermore, we use our modeling approach to study cell-type specific differences in persistent activity properties, via implementing a regular spiking (RS and an intrinsic bursting (IB model neuron. We identify synaptic location within the basal dendrites as a feature of stimulus selectivity. Specifically, persistent activity-inducing stimuli consist of activated synapses that are located more distally from the soma compared to non-inducing stimuli, in both model cells. In addition, the action potential (AP latency and the first few inter-spike-intervals of the neuronal response can be used to reliably detect inducing vs. non-inducing inputs, suggesting a potential mechanism by which downstream neurons can rapidly decode the upcoming emergence of persistent activity. While the two model neurons did not differ in the coding features of persistent activity emergence, the properties of persistent activity, such as the firing pattern and the duration of temporally-restricted persistent activity were distinct. Collectively, our results pinpoint to specific features of the neuronal response to a given

Antagonism of a (+)N-allylnormetazocine stimulus by (-)PPAP and several structurally related analogs.

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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.

CPM Test-Retest Reliability: "Standard" vs "Single Test-Stimulus" Protocols.

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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

Can responses to basic non-numerical visual features explain neural numerosity responses?

NARCIS (Netherlands)

Harvey, Ben M; Dumoulin, Serge O

2017-01-01

Humans and many animals can distinguish between stimuli that differ in numerosity, the number of objects in a set. Human and macaque parietal lobes contain neurons that respond to changes in stimulus numerosity. However, basic non-numerical visual features can affect neural responses to and

Stimulus Sensitivity of a Spiking Neural Network Model

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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.

Design of novel non-contact multimedia controller for disability by using visual stimulus.

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Pan, Jeng-Shyang; Lo, Chi-Chun; Tsai, Shang-Ho; Lin, Bor-Shyh

2015-12-01

The design of a novel non-contact multimedia controller is proposed in this study. Nowadays, multimedia controllers are generally used by patients and nursing assistants in the hospital. Conventional multimedia controllers usually involve in manual operation or other physical movements. However, it is more difficult for the disabled patients to operate the conventional multimedia controller by themselves; they might totally depend on others. Different from other multimedia controllers, the proposed system provides a novel concept of controlling multimedia via visual stimuli, without manual operation. The disabled patients can easily operate the proposed multimedia system by focusing on the control icons of a visual stimulus device, where a commercial tablet is used as the visual stimulus device. Moreover, a wearable and wireless electroencephalogram (EEG) acquisition device is also designed and implemented to easily monitor the user's EEG signals in daily life. Finally, the proposed system has been validated. The experimental result shows that the proposed system can effectively measure and extract the EEG feature related to visual stimuli, and its information transfer rate is also good. Therefore, the proposed non-contact multimedia controller exactly provides a good prototype of novel multimedia controlling scheme. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Stimulus number, duration and intensity encoding in randomly connected attractor networks with synaptic depression

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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.

Non-linguistic learning in aphasia: Effects of training method and stimulus characteristics

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Vallila-Rohter, Sofia; Kiran, Swathi

2013-01-01

Purpose The purpose of the current study was to explore non-linguistic learning ability in patients with aphasia, examining the impact of stimulus typicality and feedback on success with learning. Method Eighteen patients with aphasia and eight healthy controls participated in this study. All participants completed four computerized, non-linguistic category-learning tasks. We probed learning ability under two methods of instruction: feedback-based (FB) and paired-associate (PA). We also examined the impact of task complexity on learning ability, comparing two stimulus conditions: typical (Typ) and atypical (Atyp). Performance was compared between groups and across conditions. Results Results demonstrated that healthy controls were able to successfully learn categories under all conditions. For our patients with aphasia, two patterns of performance arose. One subgroup of patients was able to maintain learning across task manipulations and conditions. The other subgroup of patients demonstrated a sensitivity to task complexity, learning successfully only in the typical training conditions. Conclusions Results support the hypothesis that impairments of general learning are present in aphasia. Some patients demonstrated the ability to extract category information under complex training conditions, while others learned only under conditions that were simplified and emphasized salient category features. Overall, the typical training condition facilitated learning for all participants. Findings have implications for therapy, which are discussed. PMID:23695914

Feature-Based Visual Short-Term Memory Is Widely Distributed and Hierarchically Organized.

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Dotson, Nicholas M; Hoffman, Steven J; Goodell, Baldwin; Gray, Charles M

2018-06-15

Feature-based visual short-term memory is known to engage both sensory and association cortices. However, the extent of the participating circuit and the neural mechanisms underlying memory maintenance is still a matter of vigorous debate. To address these questions, we recorded neuronal activity from 42 cortical areas in monkeys performing a feature-based visual short-term memory task and an interleaved fixation task. We find that task-dependent differences in firing rates are widely distributed throughout the cortex, while stimulus-specific changes in firing rates are more restricted and hierarchically organized. We also show that microsaccades during the memory delay encode the stimuli held in memory and that units modulated by microsaccades are more likely to exhibit stimulus specificity, suggesting that eye movements contribute to visual short-term memory processes. These results support a framework in which most cortical areas, within a modality, contribute to mnemonic representations at timescales that increase along the cortical hierarchy. Copyright © 2018 Elsevier Inc. All rights reserved.

Processing of word stress related acoustic information: A multi-feature MMN study.

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Honbolygó, Ferenc; Kolozsvári, Orsolya; Csépe, Valéria

2017-08-01

In the present study, we investigated the processing of word stress related acoustic features in a word context. In a passive oddball multi-feature MMN experiment, we presented a disyllabic pseudo-word with two acoustically similar syllables as standard stimulus, and five contrasting deviants that differed from the standard in that they were either stressed on the first syllable or contained a vowel change. Stress was realized by an increase of f0, intensity, vowel duration or consonant duration. The vowel change was used to investigate if phonemic and prosodic changes elicit different MMN components. As a control condition, we presented non-speech counterparts of the speech stimuli. Results showed all but one feature (non-speech intensity deviant) eliciting the MMN component, which was larger for speech compared to non-speech stimuli. Two other components showed stimulus related effects: the N350 and the LDN (Late Discriminative Negativity). The N350 appeared to the vowel duration and consonant duration deviants, specifically to features related to the temporal characteristics of stimuli, while the LDN was present for all features, and it was larger for speech than for non-speech stimuli. We also found that the f0 and consonant duration features elicited a larger MMN than other features. These results suggest that stress as a phonological feature is processed based on long-term representations, and listeners show a specific sensitivity to segmental and suprasegmental cues signaling the prosodic boundaries of words. These findings support a two-stage model in the perception of stress and phoneme related acoustical information. Copyright © 2017 Elsevier B.V. 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

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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.

Inference of pain stimulus level from stereotypical behavioral response of C.elegans allows quantification of effects of anesthesia and mutation

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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/.

Audio-visual synchrony and feature-selective attention co-amplify early visual processing.

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Keitel, Christian; Müller, Matthias M

2016-05-01

Our brain relies on neural mechanisms of selective attention and converging sensory processing to efficiently cope with rich and unceasing multisensory inputs. One prominent assumption holds that audio-visual synchrony can act as a strong attractor for spatial attention. Here, we tested for a similar effect of audio-visual synchrony on feature-selective attention. We presented two superimposed Gabor patches that differed in colour and orientation. On each trial, participants were cued to selectively attend to one of the two patches. Over time, spatial frequencies of both patches varied sinusoidally at distinct rates (3.14 and 3.63 Hz), giving rise to pulse-like percepts. A simultaneously presented pure tone carried a frequency modulation at the pulse rate of one of the two visual stimuli to introduce audio-visual synchrony. Pulsed stimulation elicited distinct time-locked oscillatory electrophysiological brain responses. These steady-state responses were quantified in the spectral domain to examine individual stimulus processing under conditions of synchronous versus asynchronous tone presentation and when respective stimuli were attended versus unattended. We found that both, attending to the colour of a stimulus and its synchrony with the tone, enhanced its processing. Moreover, both gain effects combined linearly for attended in-sync stimuli. Our results suggest that audio-visual synchrony can attract attention to specific stimulus features when stimuli overlap in space.

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.

Cooperative vehicle control, feature tracking and ocean sampling

Science.gov (United States)

Fiorelli, Edward A.

This dissertation concerns the development of a feedback control framework for coordinating multiple, sensor-equipped, autonomous vehicles into mobile sensing arrays to perform adaptive sampling of observed fields. The use of feedback is central; it maintains the array, i.e. regulates formation position, orientation, and shape, and directs the array to perform its sampling mission in response to measurements taken by each vehicle. Specifically, we address how to perform autonomous gradient tracking and feature detection in an unknown field such as temperature or salinity in the ocean. Artificial potentials and virtual bodies are used to coordinate the autonomous vehicles, modelled as point masses (with unit mass). The virtual bodies consist of linked, moving reference points called virtual leaders. Artificial potentials couple the dynamics of the vehicles and the virtual bodies. The dynamics of the virtual body are then prescribed allowing the virtual body, and thus the vehicle group, to perform maneuvers that include translation, rotation and contraction/expansion, while ensuring that the formation error remains bounded. This methodology is called the Virtual Body and Artificial Potential (VBAP) methodology. We then propose how to utilize these arrays to perform autonomous gradient climbing and front tracking in the presence of both correlated and uncorrelated noise. We implement various techniques for estimation of gradients (first-order and higher), including finite differencing, least squares error minimization, averaging, and Kalman filtering. Furthermore, we illustrate how the estimation error can be used to optimally choose the formation size. To complement our theoretical work, we present an account of sea trials performed with a fleet of autonomous underwater gliders in Monterey Bay during the Autonomous Ocean Sampling Network (AOSN) II project in August 2003. During these trials, Slocum autonomous underwater gliders were coordinated into triangle

Reinforcing and discriminative stimulus properties of music in goldfish.

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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)

Science.gov (United States)

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

Contributions from eye movement potentials to stimulus preceding negativity during anticipation of auditory stimulation

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

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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.

Brain bases for auditory stimulus-driven figure-ground segregation.

Science.gov (United States)

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.

Spatiotemporal Features for Asynchronous Event-based Data

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Xavier eLagorce

2015-02-01

Full Text Available Bio-inspired asynchronous event-based vision sensors are currently introducing a paradigm shift in visual information processing. These new sensors rely on a stimulus-driven principle of light acquisition similar to biological retinas. They are event-driven and fully asynchronous, thereby reducing redundancy and encoding exact times of input signal changes, leading to a very precise temporal resolution. Approaches for higher-level computer vision often rely on the realiable detection of features in visual frames, but similar definitions of features for the novel dynamic and event-based visual input representation of silicon retinas have so far been lacking. This article addresses the problem of learning and recognizing features for event-based vision sensors, which capture properties of truly spatiotemporal volumes of sparse visual event information. A novel computational architecture for learning and encoding spatiotemporal features is introduced based on a set of predictive recurrent reservoir networks, competing via winner-take-all selection. Features are learned in an unsupervised manner from real-world input recorded with event-based vision sensors. It is shown that the networks in the architecture learn distinct and task-specific dynamic visual features, and can predict their trajectories over time.

Stimulus uncertainty enhances long-term potentiation-like plasticity in human motor cortex.

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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.

Glucocorticoids mediate stress-induced impairment of retrieval of stimulus-response memory.

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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

Priming makes a stimulus more salient

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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.

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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.

Unique sudden onsets capture attention even when observers are in feature-search mode.

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Spalek, Thomas M; Yanko, Matthew R; Poiese, Paola; Lagroix, Hayley E P

2012-01-01

Two sources of attentional capture have been proposed: stimulus-driven (exogenous) and goal-oriented (endogenous). A resolution between these modes of capture has not been straightforward. Even such a clearly exogenous event as the sudden onset of a stimulus can be said to capture attention endogenously if observers operate in singleton-detection mode rather than feature-search mode. In four experiments we show that a unique sudden onset captures attention even when observers are in feature-search mode. The displays were rapid serial visual presentation (RSVP) streams of differently coloured letters with the target letter defined by a specific colour. Distractors were four #s, one of the target colour, surrounding one of the non-target letters. Capture was substantially reduced when the onset of the distractor array was not unique because it was preceded by other sets of four grey # arrays in the RSVP stream. This provides unambiguous evidence that attention can be captured both exogenously and endogenously within a single task.

Approach-Avoidance Training Effects Are Moderated by Awareness of Stimulus-Action Contingencies.

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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.

Variables Influencing Stimulus Overselectivity and "Tunnel Vision" in Developmentally Delayed Children.

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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.

Stimulus-driven capture and contingent capture

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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

Shielding voices: The modulation of binding processes between voice features and response features by task representations.

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Bogon, Johanna; Eisenbarth, Hedwig; Landgraf, Steffen; Dreisbach, Gesine

2017-09-01

Vocal events offer not only semantic-linguistic content but also information about the identity and the emotional-motivational state of the speaker. Furthermore, most vocal events have implications for our actions and therefore include action-related features. But the relevance and irrelevance of vocal features varies from task to task. The present study investigates binding processes for perceptual and action-related features of spoken words and their modulation by the task representation of the listener. Participants reacted with two response keys to eight different words spoken by a male or a female voice (Experiment 1) or spoken by an angry or neutral male voice (Experiment 2). There were two instruction conditions: half of participants learned eight stimulus-response mappings by rote (SR), and half of participants applied a binary task rule (TR). In both experiments, SR instructed participants showed clear evidence for binding processes between voice and response features indicated by an interaction between the irrelevant voice feature and the response. By contrast, as indicated by a three-way interaction with instruction, no such binding was found in the TR instructed group. These results are suggestive of binding and shielding as two adaptive mechanisms that ensure successful communication and action in a dynamic social environment.

Anticipation increases tactile stimulus processing in the ipsilateral primary somatosensory cortex.

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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.

Effects of brief time delays on matching-to-sample abilities in capuchin monkeys (Sapajus spp.).

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Truppa, Valentina; De Simone, Diego Antonio; Piano Mortari, Eva; De Lillo, Carlo

2014-09-01

Traditionally, studies of delayed matching-to-sample (DMTS) tasks in nonhuman species have focused on the assessment of the limits of the retrieval of information stored in short- and long-term memory systems. However, it is still unclear if visual recognition in these tasks is affected by very brief delay intervals, which are typically used to study rapidly decaying types of visual memory. This study aimed at evaluating if tufted capuchin monkeys' ability to recognise visual stimuli in a DMTS task is affected by (i) the disappearance of the sample stimulus and (ii) the introduction of delay intervals (0.5, 1.0, 2.0 and 3.0s) between the disappearance of the sample and the presentation of the comparison stimuli. The results demonstrated that the simple disappearance of the sample and the introduction of a delay of 0.5s did not affect capuchins' performance either in terms of accuracy or response time. A delay interval of 1.0s produced a significant increase in response time but still did not affect recognition accuracy. By contrast, delays of 2.0 and 3.0s determined a significant increase in response time and a reduction in recognition accuracy. These findings indicate the existence in capuchin monkeys of processes enabling a very accurate retention of stimulus features within time frames comparable to those reported for humans' sensory memory (0.5-1.0s). The extent to which such processes can be considered analogous to the sensory memory processes observed in human visual cognition is discussed. Copyright © 2014 Elsevier B.V. All rights reserved.

Decoupling Stimulus Duration from Brightness in Metacontrast Masking: Data and Models

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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,…

Differences in the Stimulus Accommodative Convergence/Accommodation Ratio using Various Techniques and Accommodative Stimuli.

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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.

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 specificity of a steady-state visual-evoked potential-based brain-computer interface

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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.

Dynamic integration of reward and stimulus information in perceptual decision-making.

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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.

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.

Stimulus fear-relevance and the vicarious learning pathway to childhood fears.

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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.

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.

The Poverty of the Mayan Stimulus

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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"…

Stimulus-response mappings shape inhibition processes: a combined EEG-fMRI study of contextual stopping.

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Christina F Lavallee

Full Text Available Humans are rarely faced with one simple task, but are typically confronted with complex stimulus constellations and varying stimulus-relevance in a given situation. Through modifying the prototypical stop-signal task and by combined recording and analysis of electroencephalography (EEG and functional magnetic resonance imaging (fMRI, we studied the effects of stimulus relevance for the generation of a response or its inhibition. Stimulus response mappings were modified by contextual cues, indicating which of two different stimuli following a go stimulus was relevant for stopping. Overall, response inhibition, that is comparing successful stopping to a stop-signal against go-signal related processes, was associated with increased activity in right inferior and left midfrontal regions, as well as increased EEG delta and theta power; however, stimulus-response conditions in which the most infrequent stop-signal was relevant for inhibition, were associated with decreased activity in regions typically involved in response inhibition, as well as decreased activity in the delta and theta bands as compared to conditions wherein the relevant stop-signal frequency was higher. Behaviorally, this (aforementioned condition, which demanded inhibition only from the most infrequent stimulus, was also associated with reduced reaction times and lower error rates. This pattern of results does not align with typical stimulus frequency-driven findings and suggests interplay between task relevance and stimulus frequency of the stop-signal. Moreover, with a multimodal EEG-fMRI analysis, we demonstrated significant parameterization for response inhibition with delta, theta and beta time-frequency values, which may be interpreted as reflecting conflict monitoring, evaluative and/or motor processes as suggested by previous work (Huster et al., 2013; Aron, 2011. Further multimodal results suggest a possible neurophysiological and behavioral benefit under conditions

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...

Effects of age, gender, and stimulus presentation period on visual short-term memory.

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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.

One for all: The effect of extinction stimulus typicality on return of fear.

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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.

Discriminative stimulus effects of alpidem, a new imidazopyridine anxiolytic.

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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)

Different responses of spontaneous and stimulus-related alpha activity to ambient luminance changes.

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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.

BOLDSync: a MATLAB-based toolbox for synchronized stimulus presentation in functional MRI.

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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.

Neural basis of feature-based contextual effects on visual search behavior

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Kelly eShen

2012-01-01

Full Text Available Searching for a visual object is known to be adaptable to context, and it is thought to result from the selection of neural representations distributed on a visual salience map, wherein stimulus-driven and goal-directed signals are combined. Here we investigated the neural basis of this adaptability by recording superior colliculus (SC neurons while three female rhesus monkeys (Macaca mulatta searched with saccadic eye movements for a target presented in an array of visual stimuli whose feature composition varied from trial to trial. We found that sensory-motor activity associated with distracters was enhanced or suppressed depending on the search array composition and that it corresponded to the monkey's search strategy, as assessed by the distribution of the occasional errant saccades. This feature-related modulation occurred independently from the saccade goal and facilitated the process of saccade target selection. We also observed feature-related enhancement in the activity associated with distracters that had been the search target during the previous session. Consistent with recurrent processing, both feature-related neuronal modulations occurred more than 60 ms after the onset of the visually evoked responses, and their near coincidence with the time of saccade target selection suggests that they are integral to this process. These results suggest that SC neuronal activity is shaped by the visual context as dictated by both stimulus-driven and goal-directed signals. Given the close proximity of the SC to the motor circuit, our findings suggest a direct link between perception and action and no need for distinct salience and motor maps.

Stimulus Predifferentiation and Modification of Children's Racial Attitudes

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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)

The feature-weighted receptive field: an interpretable encoding model for complex feature spaces.

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St-Yves, Ghislain; Naselaris, Thomas

2017-06-20

We introduce the feature-weighted receptive field (fwRF), an encoding model designed to balance expressiveness, interpretability and scalability. The fwRF is organized around the notion of a feature map-a transformation of visual stimuli into visual features that preserves the topology of visual space (but not necessarily the native resolution of the stimulus). The key assumption of the fwRF model is that activity in each voxel encodes variation in a spatially localized region across multiple feature maps. This region is fixed for all feature maps; however, the contribution of each feature map to voxel activity is weighted. Thus, the model has two separable sets of parameters: "where" parameters that characterize the location and extent of pooling over visual features, and "what" parameters that characterize tuning to visual features. The "where" parameters are analogous to classical receptive fields, while "what" parameters are analogous to classical tuning functions. By treating these as separable parameters, the fwRF model complexity is independent of the resolution of the underlying feature maps. This makes it possible to estimate models with thousands of high-resolution feature maps from relatively small amounts of data. Once a fwRF model has been estimated from data, spatial pooling and feature tuning can be read-off directly with no (or very little) additional post-processing or in-silico experimentation. We describe an optimization algorithm for estimating fwRF models from data acquired during standard visual neuroimaging experiments. We then demonstrate the model's application to two distinct sets of features: Gabor wavelets and features supplied by a deep convolutional neural network. We show that when Gabor feature maps are used, the fwRF model recovers receptive fields and spatial frequency tuning functions consistent with known organizational principles of the visual cortex. We also show that a fwRF model can be used to regress entire deep

Aural, visual, and pictorial stimulus formats in false recall.

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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.

Is conscious stimulus identification dependent on knowledge of the perceptual modality? Testing the "source misidentification hypothesis"

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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....

The Sensory Features of a Food Cue Influence Its Ability to Act as an Incentive Stimulus and Evoke Dopamine Release in the Nucleus Accumbens Core

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Singer, Bryan F.; Bryan, Myranda A.; Popov, Pavlo; Scarff, Raymond; Carter, Cody; Wright, Erin; Aragona, Brandon J.; Robinson, Terry E.

2016-01-01

The sensory properties of a reward-paired cue (a conditioned stimulus; CS) may impact the motivational value attributed to the cue, and in turn influence the form of the conditioned response (CR) that develops. A cue with multiple sensory qualities, such as a moving lever-CS, may activate numerous neural pathways that process auditory and visual…

Right-hemispheric processing of non-linguistic word features

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Baumgaertner, Annette; Hartwigsen, Gesa; Roman Siebner, Hartwig

2013-01-01

-hemispheric homologues of classic left-hemispheric language areas may partly be due to processing nonlinguistic perceptual features of verbal stimuli. We used functional MRI (fMRI) to clarify the role of the right hemisphere in the perception of nonlinguistic word features in healthy individuals. Participants made...... perceptual, semantic, or phonological decisions on the same set of auditorily and visually presented word stimuli. Perceptual decisions required judgements about stimulus-inherent changes in font size (visual modality) or fundamental frequency contour (auditory modality). The semantic judgement required......, the right inferior frontal gyrus (IFG), an area previously suggested to support language recovery after left-hemispheric stroke, displayed modality-independent activation during perceptual processing of word stimuli. Our findings indicate that activation of the right hemisphere during language tasks may...

Stimulus induced bursts in severe postanoxic encephalopathy.

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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.

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

Accurate Delayed Matching-to-Sample Responding without Rehearsal: An Unintentional Demonstration with Children

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Ratkos, Thom; Frieder, Jessica E.; Poling, Alan

2016-01-01

Research on joint control has focused on mediational responses, in which simultaneous stimulus control from two sources leads to the emission of a single response, such as choosing a comparison stimulus in delayed matching-to-sample. Most recent studies of joint control examined the role of verbal mediators (i.e., rehearsal) in evoking accurate…

Inhibition of somatosensory-evoked cortical responses by a weak leading stimulus.

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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.

Occipital Alpha and Gamma Oscillations Support Complementary Mechanisms for Processing Stimulus Value Associations.

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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.

The influence of common stimulus parameters on distortion product otoacoustic emission fine structure.

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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.

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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.

Conditioned pain modulation is minimally influenced by cognitive evaluation or imagery of the conditioning stimulus

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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

A preliminary evaluation of the validity of binge-eating disorder defining features in a community-based sample.

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Klein, Kelly M; Forney, K Jean; Keel, Pamela K

2016-05-01

Little empirical attention has been paid to the DSM-5 definition of binge-eating disorder (BED), particularly to the associated features of binge episodes. The present study sought to determine how the associated features and undue influence of weight/shape on self-evaluation contribute to evidence of a clinically significant eating disorder. Secondary analyses were conducted on data (N = 80; 76.3% women, 76.3% Caucasian, ages 18-43) collected through an epidemiological study of eating patterns. Descriptive statistics were used to report the sample prevalence of the features, independently and in combination. Correlations and alpha reliability were employed to examine relationships among associated features, distress regarding bingeing, and clinical diagnosis. Regression models and receiver-operating characteristic (ROC) curves were used to determine the utility of the features for explaining variance in distress. Internal consistency reliability for indicators was low, and several features demonstrated low or nonsignificant associations with distress and diagnosis. Feeling disgusted/depressed/guilty was the only unique predictor of distress (p = 0.001). For the ROC curves, three features was the best threshold for predicting distress. Results support the need to refine the features to ensure better detection of clinically significant eating pathology for research inclusion and treatment of the illness. © 2015 Wiley Periodicals, Inc. (Int J Eat Disord 2016; 49:524-528). © 2015 Wiley Periodicals, Inc.

Vibration and acoustic frequency spectra for industrial process modeling using selective fusion multi-condition samples and multi-source features

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Tang, Jian; Qiao, Junfei; Wu, ZhiWei; Chai, Tianyou; Zhang, Jian; Yu, Wen

2018-01-01

Frequency spectral data of mechanical vibration and acoustic signals relate to difficult-to-measure production quality and quantity parameters of complex industrial processes. A selective ensemble (SEN) algorithm can be used to build a soft sensor model of these process parameters by fusing valued information selectively from different perspectives. However, a combination of several optimized ensemble sub-models with SEN cannot guarantee the best prediction model. In this study, we use several techniques to construct mechanical vibration and acoustic frequency spectra of a data-driven industrial process parameter model based on selective fusion multi-condition samples and multi-source features. Multi-layer SEN (MLSEN) strategy is used to simulate the domain expert cognitive process. Genetic algorithm and kernel partial least squares are used to construct the inside-layer SEN sub-model based on each mechanical vibration and acoustic frequency spectral feature subset. Branch-and-bound and adaptive weighted fusion algorithms are integrated to select and combine outputs of the inside-layer SEN sub-models. Then, the outside-layer SEN is constructed. Thus, "sub-sampling training examples"-based and "manipulating input features"-based ensemble construction methods are integrated, thereby realizing the selective information fusion process based on multi-condition history samples and multi-source input features. This novel approach is applied to a laboratory-scale ball mill grinding process. A comparison with other methods indicates that the proposed MLSEN approach effectively models mechanical vibration and acoustic signals.

Crisis, Stimulus Package and Migration in China

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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

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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…

In vivo stimulus presentation to the mouse vomeronasal system: Surgery, experiment, setup, and software.

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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.

Crossmodal integration enhances neural representation of task-relevant features in audiovisual face perception.

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Li, Yuanqing; Long, Jinyi; Huang, Biao; Yu, Tianyou; Wu, Wei; Liu, Yongjian; Liang, Changhong; Sun, Pei

2015-02-01

Previous studies have shown that audiovisual integration improves identification performance and enhances neural activity in heteromodal brain areas, for example, the posterior superior temporal sulcus/middle temporal gyrus (pSTS/MTG). Furthermore, it has also been demonstrated that attention plays an important role in crossmodal integration. In this study, we considered crossmodal integration in audiovisual facial perception and explored its effect on the neural representation of features. The audiovisual stimuli in the experiment consisted of facial movie clips that could be classified into 2 gender categories (male vs. female) or 2 emotion categories (crying vs. laughing). The visual/auditory-only stimuli were created from these movie clips by removing the auditory/visual contents. The subjects needed to make a judgment about the gender/emotion category for each movie clip in the audiovisual, visual-only, or auditory-only stimulus condition as functional magnetic resonance imaging (fMRI) signals were recorded. The neural representation of the gender/emotion feature was assessed using the decoding accuracy and the brain pattern-related reproducibility indices, obtained by a multivariate pattern analysis method from the fMRI data. In comparison to the visual-only and auditory-only stimulus conditions, we found that audiovisual integration enhanced the neural representation of task-relevant features and that feature-selective attention might play a role of modulation in the audiovisual integration. © The Author 2013. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

The Bodily Expressive Action Stimulus Test (BEAST). Construction and Validation of a Stimulus Basis for Measuring Perception of Whole Body Expression of Emotions.

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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.

Parenting, relational aggression, and borderline personality features: associations over time in a Russian longitudinal sample.

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Nelson, David A; Coyne, Sarah M; Swanson, Savannah M; Hart, Craig H; Olsen, Joseph A

2014-08-01

Crick, Murray-Close, and Woods (2005) encouraged the study of relational aggression as a developmental precursor to borderline personality features in children and adolescents. A longitudinal study is needed to more fully explore this association, to contrast potential associations with physical aggression, and to assess generalizability across various cultural contexts. In addition, parenting is of particular interest in the prediction of aggression or borderline personality disorder. Early aggression and parenting experiences may differ in their long-term prediction of aggression or borderline features, which may have important implications for early intervention. The currrent study incorporated a longitudinal sample of preschool children (84 boys, 84 girls) living in intact, two-parent biological households in Voronezh, Russia. Teachers provided ratings of children's relational and physical aggression in preschool. Mothers and fathers also self-reported their engagement in authoritative, authoritarian, permissive, and psychological controlling forms of parenting with their preschooler. A decade later, 70.8% of the original child participants consented to a follow-up study in which they completed self-reports of relational and physical aggression and borderline personality features. The multivariate results of this study showed that preschool relational aggression in girls predicted adolescent relational aggression. Preschool aversive parenting (i.e., authoritarian, permissive, and psychologically controlling forms) significantly predicted aggression and borderline features in adolescent females. For adolescent males, preschool authoritative parenting served as a protective factor against aggression and borderline features, whereas authoritarian parenting was a risk factor for later aggression.

Borderline Personality Disorder Features Are Associated with Concurrent Pain-Related Disability in a Chronic Pain Sample.

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Reynolds, Caleb J; Tragesser, Sarah L

2018-04-03

To determine whether core features of borderline personality disorder are associated with increased rates of being on disability benefits due to chronic pain conditions. A total of 147 patients currently in treatment for chronic pain at a multimodal chronic pain clinic. We tested for a concurrent relationship between borderline personality disorder features and employment status using self-report measures. Borderline personality disorder features were associated with increased likelihood of currently being on disability due to pain conditions (odds ratio [OR] = 23.13, 95% confidence interval [CI] = 1.68-318.73), on disability due to other conditions (OR = 33.65, 95% CI = 2.15-526.13), and unemployed (OR = 20.14, 95% CI = 1.38-294.93), even while controlling for pain severity and interference, depression, and trait anxiety. A follow-up analysis revealed that these associations were due to the negative relationships facet of borderline personality disorder features. Borderline personality disorder features, particularly negative relationships, are associated with increased rates of pain disability, general disability, and unemployment in a chronic pain sample. Future research should examine mechanisms by which the maladaptive interpersonal behaviors and cognitions of borderline personality disorder might result in worse long-term employment outcomes of chronic pain.

Utilization of reward-prospect enhances preparatory attention and reduces stimulus conflict.

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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 recognition occurs under high perceptual load: Evidence from correlated flankers.

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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).

Right-hemispheric processing of non-linguistic word features: implications for mapping language recovery after stroke.

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Baumgaertner, Annette; Hartwigsen, Gesa; Roman Siebner, Hartwig

2013-06-01

Verbal stimuli often induce right-hemispheric activation in patients with aphasia after left-hemispheric stroke. This right-hemispheric activation is commonly attributed to functional reorganization within the language system. Yet previous evidence suggests that functional activation in right-hemispheric homologues of classic left-hemispheric language areas may partly be due to processing nonlinguistic perceptual features of verbal stimuli. We used functional MRI (fMRI) to clarify the role of the right hemisphere in the perception of nonlinguistic word features in healthy individuals. Participants made perceptual, semantic, or phonological decisions on the same set of auditorily and visually presented word stimuli. Perceptual decisions required judgements about stimulus-inherent changes in font size (visual modality) or fundamental frequency contour (auditory modality). The semantic judgement required subjects to decide whether a stimulus is natural or man-made; the phonologic decision required a decision on whether a stimulus contains two or three syllables. Compared to phonologic or semantic decision, nonlinguistic perceptual decisions resulted in a stronger right-hemispheric activation. Specifically, the right inferior frontal gyrus (IFG), an area previously suggested to support language recovery after left-hemispheric stroke, displayed modality-independent activation during perceptual processing of word stimuli. Our findings indicate that activation of the right hemisphere during language tasks may, in some instances, be driven by a "nonlinguistic perceptual processing" mode that focuses on nonlinguistic word features. This raises the possibility that stronger activation of right inferior frontal areas during language tasks in aphasic patients with left-hemispheric stroke may at least partially reflect increased attentional focus on nonlinguistic perceptual aspects of language. Copyright © 2012 Wiley Periodicals, Inc.

Slow feature analysis: unsupervised learning of invariances.

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Wiskott, Laurenz; Sejnowski, Terrence J

2002-04-01

Invariant features of temporally varying signals are useful for analysis and classification. Slow feature analysis (SFA) is a new method for learning invariant or slowly varying features from a vectorial input signal. It is based on a nonlinear expansion of the input signal and application of principal component analysis to this expanded signal and its time derivative. It is guaranteed to find the optimal solution within a family of functions directly and can learn to extract a large number of decorrelated features, which are ordered by their degree of invariance. SFA can be applied hierarchically to process high-dimensional input signals and extract complex features. SFA is applied first to complex cell tuning properties based on simple cell output, including disparity and motion. Then more complicated input-output functions are learned by repeated application of SFA. Finally, a hierarchical network of SFA modules is presented as a simple model of the visual system. The same unstructured network can learn translation, size, rotation, contrast, or, to a lesser degree, illumination invariance for one-dimensional objects, depending on only the training stimulus. Surprisingly, only a few training objects suffice to achieve good generalization to new objects. The generated representation is suitable for object recognition. Performance degrades if the network is trained to learn multiple invariances simultaneously.

Simple 3-D stimulus for motion parallax and its simulation.

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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.

Adolescent development of context-dependent stimulus-reward association memory and its neural correlates.

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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.

Phosphene-guided transcranial magnetic stimulation of occipital but not parietal cortex suppresses stimulus visibility

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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

Transmission electron microscope sample holder with optical features

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Milas, Mirko [Port Jefferson, NY; Zhu, Yimei [Stony Brook, NY; Rameau, Jonathan David [Coram, NY

2012-03-27

A sample holder for holding a sample to be observed for research purposes, particularly in a transmission electron microscope (TEM), generally includes an external alignment part for directing a light beam in a predetermined beam direction, a sample holder body in optical communication with the external alignment part and a sample support member disposed at a distal end of the sample holder body opposite the external alignment part for holding a sample to be analyzed. The sample holder body defines an internal conduit for the light beam and the sample support member includes a light beam positioner for directing the light beam between the sample holder body and the sample held by the sample support member.

Stimulus- and state-dependence of systematic bias in spatial attention: additive effects of stimulus-size and time-on-task.

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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.

Temporal characteristics of gustatory responses in rat parabrachial neurons vary by stimulus and chemosensitive neuron type.

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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.

Audio-visual onset differences are used to determine syllable identity for ambiguous audio-visual stimulus pairs.

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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.

Repeated stimulation, inter-stimulus interval and inter-electrode distance alters muscle contractile properties as measured by Tensiomyography.

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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.

Repeated stimulation, inter-stimulus interval and inter-electrode distance alters muscle contractile properties as measured by Tensiomyography

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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

TMS effects on subjective and objective measures of vision: stimulation intensity and pre- versus post-stimulus masking.

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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.

Characterization of the discriminative stimulus produced by the dopamine antagonist tiapride.

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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.

Stimulus Competition in Pre/Post and Online Ratings in an Evaluative Learning Design

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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…

Weapon carrying and psychopathic-like features in a population-based sample of Finnish adolescents.

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Saukkonen, Suvi; Laajasalo, Taina; Jokela, Markus; Kivivuori, Janne; Salmi, Venla; Aronen, Eeva T

2016-02-01

We investigated the prevalence of juvenile weapon carrying and psychosocial and personality-related risk factors for carrying different types of weapons in a nationally representative, population-based sample of Finnish adolescents. Specifically, we aimed to investigate psychopathic-like personality features as a risk factor for weapon carrying. The participants were 15-16-year-old adolescents from the Finnish self-report delinquency study (n = 4855). Four different groups were formed based on self-reported weapon carrying: no weapon carrying, carrying knife, gun or other weapon. The associations between psychosocial factors, psychopathic-like features and weapon carrying were examined with multinomial logistic regression analysis. 9% of the participants had carried a weapon in the past 12 months. Adolescents with a history of delinquency, victimization and antisocial friends were more likely to carry weapons in general; however, delinquency and victimization were most strongly related to gun carrying, while perceived peer delinquency (antisocial friends) was most strongly related to carrying a knife. Better academic performance was associated with a reduced likelihood of carrying a gun and knife, while feeling secure correlated with a reduced likelihood of gun carrying only. Psychopathic-like features were related to a higher likelihood of weapon carrying, even after adjusting for other risk factors. The findings of the study suggest that adolescents carrying a weapon have a large cluster of problems in their lives, which may vary based on the type of weapon carried. Furthermore, psychopathic-like features strongly relate to a higher risk of carrying a weapon.

Richer Concepts are Better Remembered: Number of Features Effects in Free Recall

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Ian Scott Hargreaves

2012-04-01

Full Text Available In four experiments, we tested the expectation that concepts associated with more semantic features would be better remembered than concepts associated with fewer semantic features. Using feature listing norms we selected sets of items for which people tend to list high numbers of features (high NoF and items for which people tend to list lower numbers of features (low NoF. Results showed more accurate free recall for high NoF concepts than for low NoF concepts in expected memory tasks (Experiments 1-3 and also in an unexpected memory task (Experiment 4. This effect was not the result of associative chaining between study items (Experiment 3, and can be attributed to the amount of item-specific processing that occurs at study (Experiment 4. These results provide evidence that stimulus-specific differences in processing at encoding have consequences for explicit memory retrieval.

Post-stimulus endogenous and exogenous oscillations are differentially modulated by task difficulty.

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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.

Callous-Unemotional Features, Behavioral Inhibition, and Parenting: Independent Predictors of Aggression in a High-Risk Preschool Sample

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Kimonis, Eva R.; Frick, Paul J.; Boris, Neil W.; Smyke, Anna T.; Cornell, Amy H.; Farrell, Jamie M.; Zeanah, Charles H.

2006-01-01

A behaviorally-uninhibited temperament, callous-unemotional (CU) features, and harsh parenting have been associated with specific patterns of aggressive behavior in older children and adolescents. We tested the additive and interactive effects of these factors in predicting different types of aggressive behavior in a high-risk preschool sample.…

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.

Assessing Generative Braille Responding Following Training in a Matching-to-Sample Format

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Putnam, Brittany C.; Tiger, Jeffrey H.

2016-01-01

We evaluated the effects of teaching sighted college students to select printed text letters given a braille sample stimulus in a matching-to-sample (MTS) format on the emergence of untrained (a) construction of print characters given braille samples, (b) construction of braille characters given print samples, (c) transcription of print characters…

Self-triggered assistive stimulus training improves step initiation in persons with Parkinson’s disease

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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.

Neural correlates of context-dependent feature conjunction learning in visual search tasks.

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Reavis, Eric A; Frank, Sebastian M; Greenlee, Mark W; Tse, Peter U

2016-06-01

Many perceptual learning experiments show that repeated exposure to a basic visual feature such as a specific orientation or spatial frequency can modify perception of that feature, and that those perceptual changes are associated with changes in neural tuning early in visual processing. Such perceptual learning effects thus exert a bottom-up influence on subsequent stimulus processing, independent of task-demands or endogenous influences (e.g., volitional attention). However, it is unclear whether such bottom-up changes in perception can occur as more complex stimuli such as conjunctions of visual features are learned. It is not known whether changes in the efficiency with which people learn to process feature conjunctions in a task (e.g., visual search) reflect true bottom-up perceptual learning versus top-down, task-related learning (e.g., learning better control of endogenous attention). Here we show that feature conjunction learning in visual search leads to bottom-up changes in stimulus processing. First, using fMRI, we demonstrate that conjunction learning in visual search has a distinct neural signature: an increase in target-evoked activity relative to distractor-evoked activity (i.e., a relative increase in target salience). Second, we demonstrate that after learning, this neural signature is still evident even when participants passively view learned stimuli while performing an unrelated, attention-demanding task. This suggests that conjunction learning results in altered bottom-up perceptual processing of the learned conjunction stimuli (i.e., a perceptual change independent of the task). We further show that the acquired change in target-evoked activity is contextually dependent on the presence of distractors, suggesting that search array Gestalts are learned. Hum Brain Mapp 37:2319-2330, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Search asymmetry: a diagnostic for preattentive processing of separable features.

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Treisman, A; Souther, J

1985-09-01

The search rate for a target among distractors may vary dramatically depending on which stimulus plays the role of target and which that of distractors. For example, the time required to find a circle distinguished by an intersecting line is independent of the number of regular circles in the display, whereas the time to find a regular circle among circles with lines increases linearly with the number of distractors. The pattern of performance suggests parallel processing when the target has a unique distinguishing feature and serial self-terminating search when the target is distinguished only by the absence of a feature that is present in all the distractors. The results are consistent with feature-integration theory (Treisman & Gelade, 1980), which predicts that a single feature should be detected by the mere presence of activity in the relevant feature map, whereas tasks that require subjects to locate multiple instances of a feature demand focused attention. Search asymmetries may therefore offer a new diagnostic to identify the primitive features of early vision. Several candidate features are examined in this article: Colors, line ends or terminators, and closure (in the sense of a partly or wholly enclosed area) appear to be functional features; connectedness, intactness (absence of an intersecting line), and acute angles do not.

A Fast and Robust Feature-Based Scan-Matching Method in 3D SLAM and the Effect of Sampling Strategies

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Cihan Ulas

2013-11-01

Full Text Available Simultaneous localization and mapping (SLAM plays an important role in fully autonomous systems when a GNSS (global navigation satellite system is not available. Studies in both 2D indoor and 3D outdoor SLAM are based on the appearance of environments and utilize scan-matching methods to find rigid body transformation parameters between two consecutive scans. In this study, a fast and robust scan-matching method based on feature extraction is introduced. Since the method is based on the matching of certain geometric structures, like plane segments, the outliers and noise in the point cloud are considerably eliminated. Therefore, the proposed scan-matching algorithm is more robust than conventional methods. Besides, the registration time and the number of iterations are significantly reduced, since the number of matching points is efficiently decreased. As a scan-matching framework, an improved version of the normal distribution transform (NDT is used. The probability density functions (PDFs of the reference scan are generated as in the traditional NDT, and the feature extraction - based on stochastic plane detection - is applied to the only input scan. By using experimental dataset belongs to an outdoor environment like a university campus, we obtained satisfactory performance results. Moreover, the feature extraction part of the algorithm is considered as a special sampling strategy for scan-matching and compared to other sampling strategies, such as random sampling and grid-based sampling, the latter of which is first used in the NDT. Thus, this study also shows the effect of the subsampling on the performance of the NDT.

Evaluation of an Efficient Method for Training Staff to Implement Stimulus Preference Assessments

Science.gov (United States)

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…

Neural correlates of sample-coding and reward-coding in the delay activity of neurons in the entopallium and nidopallium caudolaterale of pigeons (Columba livia).

Science.gov (United States)

Johnston, Melissa; Anderson, Catrona; Colombo, Michael

2017-01-15

We recorded neuronal activity from the nidopallium caudolaterale, the avian equivalent of mammalian prefrontal cortex, and the entopallium, the avian equivalent of the mammalian visual cortex, in four birds trained on a differential outcomes delayed matching-to-sample procedure in which one sample stimulus was followed by reward and the other was not. Despite similar incidence of reward-specific and reward-unspecific delay cell types across the two areas, overall entopallium delay activity occurred following both rewarded and non-rewarded stimuli, whereas nidopallium caudolaterale delay activity tended to occur following the rewarded stimulus but not the non-rewarded stimulus. These findings are consistent with the view that delay activity in entopallium represents a code of the sample stimulus whereas delay activity in nidopallium caudolaterale represents a code of the possibility of an upcoming reward. However, based on the types of delay cells encountered, cells in NCL also code the sample stimulus and cells in ENTO are influenced by reward. We conclude that both areas support the retention of information, but that the activity in each area is differentially modulated by factors such as reward and attentional mechanisms. Copyright © 2016 Elsevier B.V. All rights reserved.

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...

Contingent capture can occur at specific feature values: behavioral and electrophysiological evidence.

Science.gov (United States)

Jiao, Jun; Zhao, Guang; Wang, Qi; Zhang, Kan; Li, Hong; Sun, Hong-Jin; Liu, Qiang

2013-02-01

The notion that attentional top-down control can be tuned to a stimulus feature is widely accepted. Although previous studies suggested that the stimulus-driven attentional capture could be contingent on top-down attentional control settings, it was uncertain whether contingent capture can occur at a specific feature value. Three experiments were conducted to address this issue using both behavioral and ERPs measures. Participants were required to respond to one color singleton in the search display (target) but refrain from responding to the search display containing another color singleton (nontarget). When target and nontarget belonged to different color categories (Experiment 1), only the target-color cue and within category irrelevant-color cue elicited the significant cue validity effect (i.e. RTs were shorter when the target was presented at the same location as the preceding cue rather than at a different location); they also lead to a robust N2pc effect, indicative of attention-capture. In addition, these two cue types had similar attention-capturing capacity. However, when target and nontarget belonged to the same color category (Experiments 2 and 3), only the target-color cue elicited the significant cue validity effect and the robust N2pc effect. The same within category irrelevant-color cue no longer elicited the cue validity effect, and the N2pc effect was also attenuated. Present findings suggest that contingent capture can occur at a specific feature value. Copyright © 2012 Elsevier B.V. All rights reserved.

The ToMenovela – A photograph-based stimulus set for the study of social cognition with high ecological validity

Directory of Open Access Journals (Sweden)

Maike C. Herbort

2016-12-01

Full Text Available We present the ToMenovela, a stimulus set that has been developed to provide a set of normatively rated socio-emotional stimuli showing varying amount of characters in emotionally laden interactions for experimental investigations of i cognitive and ii affective ToM, iii emotional reactivity, and iv complex emotion judgment with respect to Ekman’s basic emotions (happiness, sadness, anger, fear, surprise and disgust, Ekman & Friesen, 1975. Stimuli were generated with focus on ecological validity and consist of 190 scenes depicting daily-life situations. Two or more of eight main characters with distinct biographies and personalities are depicted on each scene picture.To obtain an initial evaluation of the stimulus set and to pave the way for future studies in clinical populations, normative data on each stimulus of the set was obtained from a sample of 61 neurologically and psychiatrically healthy participants (31 female, 30 male; mean age 26.74 +/- 5.84, including a visual analog scale rating of Ekman’s basic emotions (happiness, sadness, anger, fear, surprise and disgust and free-text descriptions of the content. The ToMenovela is being developed to provide standardized material of social scenes that are available to researchers in the study of social cognition. It should facilitate experimental control while keeping ecological validity high.

Design Review Report for formal review of safety class features of exhauster system for rotary mode core sampling

International Nuclear Information System (INIS)

JANICEK, G.P.

2000-01-01

Report documenting Formal Design Review conducted on portable exhausters used to support rotary mode core sampling of Hanford underground radioactive waste tanks with focus on Safety Class design features and control requirements for flammable gas environment operation and air discharge permitting compliance

Design Review Report for formal review of safety class features of exhauster system for rotary mode core sampling

Energy Technology Data Exchange (ETDEWEB)

JANICEK, G.P.

2000-06-08

Report documenting Formal Design Review conducted on portable exhausters used to support rotary mode core sampling of Hanford underground radioactive waste tanks with focus on Safety Class design features and control requirements for flammable gas environment operation and air discharge permitting compliance.

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.

Science.gov (United States)

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.

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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.

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.

Science.gov (United States)

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.

Experimental test of contemporary mathematical models of visual letter recognition.

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Townsend, J T; Ashby, F G

1982-12-01

A letter confusion experiment that used brief durations manipulated payoffs across the four stimulus letters, which were composed of line segments equal in length. The observers were required to report the features they perceived as well as to give a letter response. The early feature-sampling process is separated from the later letter-decision process in the substantive feature models, and predictions are thus obtained for the frequencies of feature report as well as letter report. Four substantive visual feature-processing models are developed and tested against one another and against three models of a more descriptive nature. The substantive models predict the decisional letter report phase much better than they do the feature-sampling phase, but the best overall 4 X 4 letter confusion matrix fits are obtained with one of the descriptive models, the similarity choice model. The present and other recent results suggest that the assumption that features are sampled in a stochastically independent manner may not be generally valid. The traditional high-threshold conceptualization of feature sampling is also falsified by the frequent reporting by observers of features not contained in the stimulus letter.

Using Complex Auditory-Visual Samples to Produce Emergent Relations in Children with Autism

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Groskreutz, Nicole C.; Karsina, Allen; Miguel, Caio F.; Groskreutz, Mark P.

2010-01-01

Six participants with autism learned conditional relations between complex auditory-visual sample stimuli (dictated words and pictures) and simple visual comparisons (printed words) using matching-to-sample training procedures. Pre- and posttests examined potential stimulus control by each element of the complex sample when presented individually…

Discriminative identification of transcriptional responses of promoters and enhancers after stimulus

KAUST Repository

Kleftogiannis, Dimitrios A.

2016-10-17

Promoters and enhancers regulate the initiation of gene expression and maintenance of expression levels in spatial and temporal manner. Recent findings stemming from the Cap Analysis of Gene Expression (CAGE) demonstrate that promoters and enhancers, based on their expression profiles after stimulus, belong to different transcription response subclasses. One of the most promising biological features that might explain the difference in transcriptional response between subclasses is the local chromatin environment. We introduce a novel computational framework, PEDAL, for distinguishing effectively transcriptional profiles of promoters and enhancers using solely histone modification marks, chromatin accessibility and binding sites of transcription factors and co-activators. A case study on data from MCF-7 cell-line reveals that PEDAL can identify successfully the transcription response subclasses of promoters and enhancers from two different stimulations. Moreover, we report subsets of input markers that discriminate with minimized classification error MCF-7 promoter and enhancer transcription response subclasses. Our work provides a general computational approach for identifying effectively cell-specific and stimulation-specific promoter and enhancer transcriptional profiles, and thus, contributes to improve our understanding of transcriptional activation in human.

Compound Stimulus Extinction Reduces Spontaneous Recovery in Humans

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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…

Conditioned pain modulation is affected by occlusion cuff conditioning stimulus intensity, but not duration.

Science.gov (United States)

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®.

The Effect of Cell Phone Conversation on Drivers’ Reaction Time to Audio Stimulus: Investigating the Theory of Multiple Resources and Central Resource of Attention

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Seyed Kazem Mousavi-Sadati

2011-01-01

Full Text Available Objective: This research was aimed at investigating the theory of multiple resources and central resource of attention on secondary task performance of talking with two types of cell phone during driving. Materials & Methods: Using disposal sampling, 25 male participants were selected and their reaction to auditory stimulus in three different driving conditions (no conversation with phone, conversation with handheld phone and hands-free phone were recorded. Driving conditions have been changed from a participant to another participant in order to control the sequence of tests and participants familiarity with the test conditions. Results: the results of data analysis with descriptive statistics and Mauchly’s Test of Sphericity, One- factor repeated measures ANOVA and Paired-Samples T test showed that different driving conditions can affect the reaction time (P0.001. Phone Conversation with hands-free phone increases drivers’ simple reaction time to auditory stimulus (P<0.001. Using handheld phone does not increase drivers’ reaction time to auditory stimulus over hands-free phone (P<0.001. Conclusion: The results confirmed that the performance quality of dual tasks and multiple tasks can be predicted by Four-dimensional multiple resources model of attention and all traffic laws in connection with the handheld phone also have to be spread to the use of hands-free phone.

A dissociation of dorso-lateral striatum and amygdala function on the same stimulus-response habit task.

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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.

Stimulus meanings alter illusory self-motion (vection)--experimental examination of the train illusion.

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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.

Efficacy of a new charge-balanced biphasic electrical stimulus in the isolated sciatic nerve and the hippocampal slice

NARCIS (Netherlands)

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

Stimulus-Food Pairings Produce Stimulus-Directed Touch Screen Responding in Cynomolgus Monkeys ("Macaca Fascicularis") with or without a Positive Response Contingency

Science.gov (United States)

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…

The Roles of Feature-Specific Task Set and Bottom-Up Salience in Attentional Capture: An ERP Study

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Eimer, Martin; Kiss, Monika; Press, Clare; Sauter, Disa

2009-01-01

We investigated the roles of top-down task set and bottom-up stimulus salience for feature-specific attentional capture. Spatially nonpredictive cues preceded search arrays that included a color-defined target. For target-color singleton cues, behavioral spatial cueing effects were accompanied by cue-induced N2pc components, indicative of…

Neuronal representations of stimulus associations develop in the temporal lobe during learning

OpenAIRE

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...

The 5-HT1A Receptor and the Stimulus Effects of LSD in the Rat

Science.gov (United States)

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

Taxometric Analysis of the Antisocial Features Scale of the Personality Assessment Inventory in Federal Prison Inmates

Science.gov (United States)

Walters, Glenn D.; Diamond, Pamela M.; Magaletta, Philip R.; Geyer, Matthew D.; Duncan, Scott A.

2007-01-01

The Antisocial Features (ANT) scale of the Personality Assessment Inventory (PAI) was subjected to taxometric analysis in a group of 2,135 federal prison inmates. Scores on the three ANT subscales--Antisocial Behaviors (ANT-A), Egocentricity (ANT-E), and Stimulus Seeking (ANT-S)--served as indicators in this study and were evaluated using the…

Cortical dynamics of feature binding and reset: control of visual persistence.

Science.gov (United States)

Francis, G; Grossberg, S; Mingolla, E

1994-04-01

An analysis of the reset of visual cortical circuits responsible for the binding or segmentation of visual features into coherent visual forms yields a model that explains properties of visual persistence. The reset mechanisms prevent massive smearing of visual percepts in response to rapidly moving images. The model simulates relationships among psychophysical data showing inverse relations of persistence to flash luminance and duration, greater persistence of illusory contours than real contours, a U-shaped temporal function for persistence of illusory contours, a reduction of persistence due to adaptation with a stimulus of like orientation, an increase of persistence with spatial separation of a masking stimulus. The model suggests that a combination of habituative, opponent, and endstopping mechanisms prevent smearing and limit persistence. Earlier work with the model has analyzed data about boundary formation, texture segregation, shape-from-shading, and figure-ground separation. Thus, several types of data support each model mechanism and new predictions are made.

Dyslexic adults can learn from repeated stimulus presentation but have difficulties in excluding external noise.

Directory of Open Access Journals (Sweden)

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.

Feature integration and spatial attention: common processes for endogenous and exogenous orienting.

Science.gov (United States)

Henderickx, David; Maetens, Kathleen; Soetens, Eric

2010-05-01

Briand (J Exp Psychol Hum Percept Perform 24:1243-1256, 1998) and Briand and Klein (J Exp Psychol Hum Percept Perform 13:228-241, 1987) demonstrated that spatial cueing effects are larger for detecting conjunction of features than for detecting simple features when spatial attention is oriented exogenously, and not when attention is oriented endogenously. Their results were interpreted as if only exogenous attention affects the posterior spatial attention system that performs the feature binding function attributed to spatial attention by Treisman's feature integration theory (FIT; 1980). In a series of 6 experiments, we attempted to replicate Briand's findings. Manipulations of distractor string size and symmetry of stimulus presentation left and right from fixation were implemented in Posner's cueing paradigm. The data indicate that both exogenous and endogenous cueing address the same attentional mechanism needed for feature binding. The results also limit the generalisability of Briand's proposal concerning the role of exogenous attention in feature integration. Furthermore, the importance to control the effect of unintended attentional capture in a cueing task is demonstrated.

On the respective contributions of awareness of unconditioned stimulus valence and unconditioned stimulus identity in attitude formation through evaluative conditioning.

Science.gov (United States)

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).

Flexible goal imitation: Vicarious feedback influences stimulus-response binding by observation.

Science.gov (United States)

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.

Science.gov (United States)

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.

Science.gov (United States)

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.

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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.

Prototypic Features of Loneliness in a Stratified Sample of Adolescents

DEFF Research Database (Denmark)

Lasgaard, Mathias; Elklit, Ask

2009-01-01

Dominant theoretical approaches in loneliness research emphasize the value of personality characteristics in explaining loneliness. The present study examines whether dysfunctional social strategies and attributions in lonely adolescents can be explained by personality characteristics...... guidance and intervention. Thus, professionals need to be knowledgeable about prototypic features of loneliness in addition to employing a pro-active approach when assisting adolescents who display prototypic features....

The fate of task-irrelevant visual motion: perceptual load versus feature-based attention.

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Taya, Shuichiro; Adams, Wendy J; Graf, Erich W; Lavie, Nilli

2009-11-18

We tested contrasting predictions derived from perceptual load theory and from recent feature-based selection accounts. Observers viewed moving, colored stimuli and performed low or high load tasks associated with one stimulus feature, either color or motion. The resultant motion aftereffect (MAE) was used to evaluate attentional allocation. We found that task-irrelevant visual features received less attention than co-localized task-relevant features of the same objects. Moreover, when color and motion features were co-localized yet perceived to belong to two distinct surfaces, feature-based selection was further increased at the expense of object-based co-selection. Load theory predicts that the MAE for task-irrelevant motion would be reduced with a higher load color task. However, this was not seen for co-localized features; perceptual load only modulated the MAE for task-irrelevant motion when this was spatially separated from the attended color location. Our results suggest that perceptual load effects are mediated by spatial selection and do not generalize to the feature domain. Feature-based selection operates to suppress processing of task-irrelevant, co-localized features, irrespective of perceptual load.

The role of the right superior temporal gyrus in stimulus-centered spatial processing.

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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

VENOUS SAMPLING FOR CUSHING DISEASE: COMPARISON OF INTERNAL JUGULAR VEIN AND INFERIOR PETROSAL SINUS SAMPLING.

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Radvany, Martin G; Quinones-Hinojosa, Alfredo; Gallia, Gary L; Wand, Gary S; Salvatori, Roberto

2016-09-01

Because magnetic resonance imaging (MRI) fails to detect many adrenocorticotropic hormone (ACTH)-secreting pituitary adenomas, inferior petrosal sinus sampling (IPSS) is considered the gold standard to differentiate Cushing disease (CD) from ectopic ACTH secretion syndrome (EAS). Some authors have suggested internal jugular vein sampling (IJVS) as an alternative to IPSS. We simultaneously compared IJVS to IPSS in 30 consecutive patients referred for ACTH-dependent Cushing syndrome and equivocal MRI exams. Five sites were simultaneously sampled in each patient (right and left IPS, right and left IJV, and femoral vein) before and after the administration of corticotrophin-releasing hormone or desmopressin. The test was considered consistent with CD when the IPS to peripheral ratio was >2 at baseline or >3 after stimulus and the IJV to peripheral ratio was >1.7 at baseline or >2 after stimulus. In 27 of 30 patients, IPSS results were consistent with a central source of ACTH. Two of the other 3 patients had EAS (one lung carcinoid and one occult), and 1 patient had pathology-proven CD. The sensitivity of IPSS was 96.4%. Only 64.2% of these patients had results meeting criteria for a central source of ACTH by IJVS criteria. Twenty patients with centralizing IPPS have undergone pituitary surgery. Of these, the central origin of excessive ACTH was confirmed with certainty in 16 patients. Among these 16 patients, the IPSS sensitivity was 93.8%, whereas 5 patients had false-negative IJVS (68.7% sensitivity). These results do not support the routine use of IJVS in establishing if the pituitary is the source of excessive ACTH. ACTH = adrenocorticotropic hormone CD = Cushing disease CRH = corticotrophin-releasing hormone CS = Cushing syndrome DDAVP = desmopressin EAS = ectopic ACTH secretion IJVS = internal jugular vein sampling IPSS = inferior petrosal sinus sampling JVS = jugular venous sampling MRI = magnetic resonance imaging.

Stimulus-Response Compatibility effect in the near-far dimension: A developmental study

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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.

Effects of Stimulus Characteristics and Background Music on Foreign Language Vocabulary Learning and Forgetting

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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…

Imitation in Infancy: The Wealth of the Stimulus

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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,…

Influence of salinity stress on the height and productivity features of durum wheat samples in different phases of vegetation

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A. Z. Sikhmuradov

2010-01-01

Full Text Available Influence of salinity stress on the morphological features of durum wheat in different phases of vegetation is studied in the work. It is revealed that in earlier phases the samples have weak stability, but further salt-stability increases.

Once on the Lips, Forever on the Hips: A Benefit-Cost Analysis of Fiscal Stimulus in OECD Countries

OpenAIRE

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.

A toolbox and sample object perception data for equalization of natural images

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Wilma A. Bainbridge

2015-12-01

Full Text Available For psychologists and neuroscientists, careful selection of their stimuli is essential, so that low-level visual features such as color or spatial frequency do not serve as confounds between conditions of interest. Here, we detail the Natural Image Statistical Toolbox, which allows scientists to measure, visualize, and control stimulus sets along a set of low-level visual properties. Additionally, we provide a set of object images varying along several perceptual object properties, including physical size and interaction envelope size (i.e., the space around an object transversed during an interaction, serving as a test-bed for the Natural Image Statistical Toolbox. This stimulus set is also a highly characterized set useful to psychology and neuroscience studies on object perception.

Pavlovian-Instrumental Transfer of the Discriminative Stimulus Effects of Nicotine and Ethanol in Rats

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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…

Predicting protein-ATP binding sites from primary sequence through fusing bi-profile sampling of multi-view features

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Zhang Ya-Nan

2012-05-01

Full Text Available Abstract Background Adenosine-5′-triphosphate (ATP is one of multifunctional nucleotides and plays an important role in cell biology as a coenzyme interacting with proteins. Revealing the binding sites between protein and ATP is significantly important to understand the functionality of the proteins and the mechanisms of protein-ATP complex. Results In this paper, we propose a novel framework for predicting the proteins’ functional residues, through which they can bind with ATP molecules. The new prediction protocol is achieved by combination of sequence evolutional information and bi-profile sampling of multi-view sequential features and the sequence derived structural features. The hypothesis for this strategy is single-view feature can only represent partial target’s knowledge and multiple sources of descriptors can be complementary. Conclusions Prediction performances evaluated by both 5-fold and leave-one-out jackknife cross-validation tests on two benchmark datasets consisting of 168 and 227 non-homologous ATP binding proteins respectively demonstrate the efficacy of the proposed protocol. Our experimental results also reveal that the residue structural characteristics of real protein-ATP binding sites are significant different from those normal ones, for example the binding residues do not show high solvent accessibility propensities, and the bindings prefer to occur at the conjoint points between different secondary structure segments. Furthermore, results also show that performance is affected by the imbalanced training datasets by testing multiple ratios between positive and negative samples in the experiments. Increasing the dataset scale is also demonstrated useful for improving the prediction performances.

Spatial probability aids visual stimulus discrimination

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Michael Druker

2010-08-01

Full Text Available We investigated whether the statistical predictability of a target's location would influence how quickly and accurately it was classified. Recent results have suggested that spatial probability can be a cue for the allocation of attention in visual search. One explanation for probability cuing is spatial repetition priming. In our two experiments we used probability distributions that were continuous across the display rather than relying on a few arbitrary screen locations. This produced fewer spatial repeats and allowed us to dissociate the effect of a high probability location from that of short-term spatial repetition. The task required participants to quickly judge the color of a single dot presented on a computer screen. In Experiment 1, targets were more probable in an off-center hotspot of high probability that gradually declined to a background rate. Targets garnered faster responses if they were near earlier target locations (priming and if they were near the high probability hotspot (probability cuing. In Experiment 2, target locations were chosen on three concentric circles around fixation. One circle contained 80% of targets. The value of this ring distribution is that it allowed for a spatially restricted high probability zone in which sequentially repeated trials were not likely to be physically close. Participant performance was sensitive to the high-probability circle in addition to the expected effects of eccentricity and the distance to recent targets. These two experiments suggest that inhomogeneities in spatial probability can be learned and used by participants on-line and without prompting as an aid for visual stimulus discrimination and that spatial repetition priming is not a sufficient explanation for this effect. Future models of attention should consider explicitly incorporating the probabilities of targets locations and features.

β1-Adrenoceptor in the Central Amygdala Is Required for Unconditioned Stimulus-Induced Drug Memory Reconsolidation

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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

Stimulus train duration but not attention moderates γ-band entrainment abnormalities in schizophrenia

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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

A model for food and stimulus changes that signal time-based contingency changes.

Science.gov (United States)

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.

The Facial Expression Action Stimulus Test. A test battery for the assessment of face memory, face and object perception, configuration processing and facial expression recognition

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Beatrice eDe Gelder

2015-10-01

Full Text Available There are many ways to assess face perception skills. In this study, we describe a novel task battery FEAST (Facial Expression Action Stimulus Test developed to test recognition of identity and expressions of human faces as well as stimulus control categories. The FEAST consists of a neutral and emotional face memory task, a face and object identity matching task, a face and house part-to-whole matching task, and a human and animal facial expression matching task. The identity and part-to-whole matching tasks contain both upright and inverted conditions. The results provide reference data of a healthy sample of controls in two age groups for future users of the FEAST.

Continuous Flash Suppression: Stimulus Fractionation rather than Integration.

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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.

The mechanisms of feature inheritance as predicted by a systems-level model of visual attention and decision making.

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Hamker, Fred H

2008-07-15

Feature inheritance provides evidence that properties of an invisible target stimulus can be attached to a following mask. We apply a systemslevel model of attention and decision making to explore the influence of memory and feedback connections in feature inheritance. We find that the presence of feedback loops alone is sufficient to account for feature inheritance. Although our simulations do not cover all experimental variations and focus only on the general principle, our result appears of specific interest since the model was designed for a completely different purpose than to explain feature inheritance. We suggest that feedback is an important property in visual perception and provide a description of its mechanism and its role in perception.

High voltage with little current as an unconditional stimulus for taste avoidance conditioning in Lymnaea stagnalis.

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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

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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

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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.

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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.

Attention in the processing of complex visual displays: detecting features and their combinations.

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Farell, B

1984-02-01

The distinction between operations in visual processing that are parallel and preattentive and those that are serial and attentional receives both theoretical and empirical support. According to Treisman's feature-integration theory, independent features are available preattentively, but attention is required to veridically combine features into objects. Certain evidence supporting this theory is consistent with a different interpretation, which was tested in four experiments. The first experiment compared the detection of features and feature combinations while eliminating a factor that confounded earlier comparisons. The resulting priority of access to combinatorial information suggests that features and nonlocal combinations of features are not connected solely by a bottom-up hierarchical convergence. Causes of the disparity between the results of Experiment 1 and the results of previous research were investigated in three subsequent experiments. The results showed that of the two confounded factors, it was the difference in the mapping of alternatives onto responses, not the differing attentional demands of features and objects, that underlaid the results of the previous research. The present results are thus counterexamples to the feature-integration theory. Aspects of this theory are shown to be subsumed by more general principles, which are discussed in terms of attentional processes in the detection of features, objects, and stimulus alternatives.

Duration of the Unconditioned Stimulus in Appetitive Conditioning of Honeybees Differentially Impacts Learning, Long-Term Memory Strength, and the Underlying Protein Synthesis

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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…

Brief-stimulus presentations on multiform tandem schedules

OpenAIRE

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...

BESST (Bochum Emotional Stimulus Set)--a pilot validation study of a stimulus set containing emotional bodies and faces from frontal and averted views.

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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

Science.gov (United States)

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…

Statistical identification of stimulus-activated network nodes in multi-neuron voltage-sensitive dye optical recordings.

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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.

Putative inhibitory training of a stimulus makes it a facilitator: a within-subject comparison of visual and auditory stimuli in autoshaping.

Science.gov (United States)

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.

EEG machine learning with Higuchi fractal dimension and Sample Entropy as features for successful detection of depression

OpenAIRE

Cukic, Milena; Pokrajac, David; Stokic, Miodrag; Simic, slobodan; Radivojevic, Vlada; Ljubisavljevic, Milos

2018-01-01

Reliable diagnosis of depressive disorder is essential for both optimal treatment and prevention of fatal outcomes. In this study, we aimed to elucidate the effectiveness of two non-linear measures, Higuchi Fractal Dimension (HFD) and Sample Entropy (SampEn), in detecting depressive disorders when applied on EEG. HFD and SampEn of EEG signals were used as features for seven machine learning algorithms including Multilayer Perceptron, Logistic Regression, Support Vector Machines with the linea...

Beyond maximum speed—a novel two-stimulus paradigm for brain-computer interfaces based on event-related potentials (P300-BCI)

Science.gov (United States)

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.

Stimulus-dependent modulation of spontaneous low-frequency oscillations in the rat visual cortex.

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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.

The attention-weighted sample-size model of visual short-term memory: Attention capture predicts resource allocation and memory load.

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Smith, Philip L; Lilburn, Simon D; Corbett, Elaine A; Sewell, David K; Kyllingsbæk, Søren

2016-09-01

We investigated the capacity of visual short-term memory (VSTM) in a phase discrimination task that required judgments about the configural relations between pairs of black and white features. Sewell et al. (2014) previously showed that VSTM capacity in an orientation discrimination task was well described by a sample-size model, which views VSTM as a resource comprised of a finite number of noisy stimulus samples. The model predicts the invariance of [Formula: see text] , the sum of squared sensitivities across items, for displays of different sizes. For phase discrimination, the set-size effect significantly exceeded that predicted by the sample-size model for both simultaneously and sequentially presented stimuli. Instead, the set-size effect and the serial position curves with sequential presentation were predicted by an attention-weighted version of the sample-size model, which assumes that one of the items in the display captures attention and receives a disproportionate share of resources. The choice probabilities and response time distributions from the task were well described by a diffusion decision model in which the drift rates embodied the assumptions of the attention-weighted sample-size model. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

The Effects of Stimulus Presentation Rate on the Short-Term Memory of Learning Disabled Children.

Science.gov (United States)

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…

Preattentive extraction of abstract feature conjunctions from auditory stimulation as reflected by the mismatch negativity (MMN).

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Paavilainen, P; Simola, J; Jaramillo, M; Näätänen, R; Winkler, I

2001-03-01

Brain mechanisms extracting invariant information from varying auditory inputs were studied using the mismatch-negativity (MMN) brain response. We wished to determine whether the preattentive sound-analysis mechanisms, reflected by MMN, are capable of extracting invariant relationships based on abstract conjunctions between two sound features. The standard stimuli varied over a large range in frequency and intensity dimensions following the rule that the higher the frequency, the louder the intensity. The occasional deviant stimuli violated this frequency-intensity relationship and elicited an MMN. The results demonstrate that preattentive processing of auditory stimuli extends to unexpectedly complex relationships between the stimulus features.

Phasic and tonic neuron ensemble codes for stimulus-environment conjunctions in the lateral entorhinal cortex.

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Pilkiw, Maryna; Insel, Nathan; Cui, Younghua; Finney, Caitlin; Morrissey, Mark D; Takehara-Nishiuchi, Kaori

2017-07-06

The lateral entorhinal cortex (LEC) is thought to bind sensory events with the environment where they took place. To compare the relative influence of transient events and temporally stable environmental stimuli on the firing of LEC cells, we recorded neuron spiking patterns in the region during blocks of a trace eyeblink conditioning paradigm performed in two environments and with different conditioning stimuli. Firing rates of some neurons were phasically selective for conditioned stimuli in a way that depended on which room the rat was in; nearly all neurons were tonically selective for environments in a way that depended on which stimuli had been presented in those environments. As rats moved from one environment to another, tonic neuron ensemble activity exhibited prospective information about the conditioned stimulus associated with the environment. Thus, the LEC formed phasic and tonic codes for event-environment associations, thereby accurately differentiating multiple experiences with overlapping features.

Task- and age-dependent effects of visual stimulus properties on children's explicit numerosity judgments.

Science.gov (United States)

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.

Feature-level domain adaptation

DEFF Research Database (Denmark)

Kouw, Wouter M.; Van Der Maaten, Laurens J P; Krijthe, Jesse H.

2016-01-01

-level domain adaptation (flda), that models the dependence between the two domains by means of a feature-level transfer model that is trained to describe the transfer from source to target domain. Subsequently, we train a domain-adapted classifier by minimizing the expected loss under the resulting transfer...... modeled via a dropout distribution, which allows the classiffier to adapt to differences in the marginal probability of features in the source and the target domain. Our experiments on several real-world problems show that flda performs on par with state-of-the-art domainadaptation techniques.......Domain adaptation is the supervised learning setting in which the training and test data are sampled from different distributions: training data is sampled from a source domain, whilst test data is sampled from a target domain. This paper proposes and studies an approach, called feature...

The Hall-Rodriguez theory of latent inhibition: Further assessment of compound stimulus preexposure effects.

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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.

Stimulus Ratio and Level Dependence of Low- and Mid-Frequency Distortion-Product Otoacoustic Emissions

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....

Descriptive features and causal attributions of headache in an Australian community.

Science.gov (United States)

Fernandez, E; Sheffield, J

1996-04-01

The reported characteristics and causes of headache differ across individuals and between groups. Such differences are of interest from an epidemiological point of view. This study set out to identify the main descriptive features and causal attributions of headache within an Australian urban community. A sample of 261 subjects reporting headache volunteered to participate in the survey. Subjects completed a self-report questionnaire for assessing demographic variables, headache parameters (intensity, duration, etc), headache medication habits, and perceived causes of one's headache (as in the UK headache survey by Blau, 1990). Results revealed that the typical headache sufferer was a middle-aged employed individual. Migraine versus tension headache were equivalent in number, and on the average, subjects experienced moderate intensity, day-long headaches that recurred about nine times per month. With regard to causal attributions, the prevalence of headaches due to mental stress was higher than that due to any other single stimulus (eg, noise, exercise), and alcohol was the most frequent dietary cause of headache. These findings are generally consistent with those from previous surveys, although some interesting departures emerge which may be accounted for by demographic differences in the populations studied.

Victimization and psychopathic features in a population-based sample of Finnish adolescents.

Science.gov (United States)

Saukkonen, Suvi; Aronen, Eeva T; Laajasalo, Taina; Salmi, Venla; Kivivuori, Janne; Jokela, Markus

2016-10-01

We examined different forms of victimization experiences in relation to psychopathic features and whether these associations differed in boys and girls among 4855 Finnish school adolescents aged 15-16 years. Psychopathic features were measured with the Antisocial Process Screening Device- Self Report (APSD-SR). Victimization was assessed with questions about violent and abusive experiences across lifetime and within the last 12 months. Results from linear regression analysis showed that victimization was significantly associated with higher APSD-SR total scores, more strongly in girls than boys. Recent (12-month) victimization showed significance in the relationship between victimization and psychopathic features; especially recent sexual abuse and parental corporal punishment were strong determinants of higher APSD-SR total scores. The present study demonstrates novel findings on how severe victimization experiences relate to psychopathic features in community youth, especially in girls. The findings underscore the need for comprehensive evaluation of victimization experiences when psychopathic features are present in youth. Copyright © 2016 Elsevier Ltd. All rights reserved.

The developmental pattern of stimulus and response interference in a color-object Stroop task: an ERP study

Directory of Open Access Journals (Sweden)

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

Science.gov (United States)

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

Investigation of the speed of reaction on external stimulus in schizophrenic psychosis.

Science.gov (United States)

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.

Science.gov (United States)

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.

Mid-Infrared Emission Features in the ISM: Feature-to-Features Flux Ratios

Science.gov (United States)

Lu, N. Y.

1998-01-01

Using a limited, but representative sample of sources in the ISM of our Galaxy with published spectra from the Infrared Space Observatory, we analyze flux ratios between the major mid-IR emission features (EFs) centered around 6.2, 7.7, 8.6 and 11.3 mu, respectively.

IDENTIFICATION AND AUTHENTICATION OF DRY SAMPLES OF SOME MEDICINAL PLANTS USING LEAF EPIDERMAL FEATURES AS MARKER

Directory of Open Access Journals (Sweden)

Abdullahi Alanamu ABDULRAHAMAN

2016-06-01

Full Text Available Herbal medicine is the oldest and still the most widely used system of medicine in the world today and they are made exclusively from plants. However, most of these medicines or drugs are adulterated due to lack of proper identification of the plant samples. Method of checking adulteration of drug plants is the main focus of this study. The identification and authentication of dry samples of some medicinal plants were carried out using anatomical features. Twenty-five (25 plants materials were collected in Ibadan and Ilorin, Nigeria. The plants studied include Azardiracta indica, Newboudia leavis, Polyalthia longifolia, Cymbopogon citratus, Anarcardium occidentalis, Nicotiana tobbaccum, Jatropha curcas, Chromoleana odorata, Mangifera indica, Terminalia catappa, Ocimum gratisimum, Morus messosygia, Morinda lucida, Psidium guajava, Vitellaria paradoxa, Annona senegalensis, Vernonia amygdalina, Gliricidium sepium, Ravoulvia vomitora, Telferia occindentalis Citrus aurantifolia, C. limon, C. paradisi and C. sinensis. Leaf epidermal anatomy of these selected plants showed no major variations in stomatal complex types, frequency, size and shape of stomatal cells, epidermal cell wall and trichomes between fresh and dry samples. The variations that occur were between different species but not within species. Leaf epidermal anatomy, therefore, proved to be a significant tool for resolution of taxonomic confusion of dried samples of these plants.

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...

Different target-discrimination times can be followed by the same saccade-initiation timing in different stimulus conditions during visual searches

Science.gov (United States)

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

A retrospective comparison of the effects of propofol and etomidate on stimulus variables and efficacy of electroconvulsive therapy in depressed inpatients.

Science.gov (United States)

Graveland, Pieternella E; Wierdsma, André I; van den Broek, Walter W; Birkenhäger, Tom K

2013-08-01

To compare the effects of propofol and etomidate on the stimulus variables and efficacy of electroconvulsive therapy (ECT) in depressed inpatients. This retrospective study included 54 inpatients (aged 18-75 years) who met the DSM-IV criteria for major depression and were treated with bilateral ECT. For the first part of the study, the primary outcome was the mean stimulus charge per ECT session. For the second part, the main outcome measure was the proportion of patients achieving full remission. Propofol-treated patients showed a higher mean stimulus charge (etomidate = 227.58 ± 130.44, propofol = 544.91 ± 237.56, p<0.001) despite the lack of a significant difference in starting threshold doses. The propofol group had shorter mean electroencephalogram (etomidate = 69.41 ± 22.50, propofol = 42.95 ± 22.26, p<0.001) seizure duration and motor (etomidate = 46.11 ± 14.38, propofol = 22.89 ± 7.13, p<0.001) seizure duration and a higher mean number of inadequate seizures (etomidate = 0.12 ± 0.15, propofol = 0.47 ± 0.26, p<0.001). No significant differences were found between the groups for the effects of the anesthetics on the efficacy of ECT. Our study is limited by a retrospective design and the small number of patients treated with propofol restricted the sample size. Anesthesia with propofol has a significant reducing effect on seizure duration during the course of ECT which results in more inadequate seizures, despite the use of a higher mean stimulus charge. Regarding the possible effect of the anesthetics on ECT, randomized clinical trials with sufficient power to detect differences are warranted. Copyright © 2013 Elsevier Inc. All rights reserved.

Spatiotemporal dynamics of cortical representations during and after stimulus presentation

NARCIS (Netherlands)

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

The Honolulu posttraumatic stress disorder stimulus set.

Science.gov (United States)

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.

Top-down modulation of human early visual cortex after stimulus offset supports successful postcued report.

Science.gov (United States)

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.

Alteration of neural action potential patterns by axonal stimulation: the importance of stimulus location.

Science.gov (United States)

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.

Optimizing methods for linking cinematic features to fMRI data.

Science.gov (United States)

Kauttonen, Janne; Hlushchuk, Yevhen; Tikka, Pia

2015-04-15

One of the challenges of naturalistic neurosciences using movie-viewing experiments is how to interpret observed brain activations in relation to the multiplicity of time-locked stimulus features. As previous studies have shown less inter-subject synchronization across viewers of random video footage than story-driven films, new methods need to be developed for analysis of less story-driven contents. To optimize the linkage between our fMRI data collected during viewing of a deliberately non-narrative silent film 'At Land' by Maya Deren (1944) and its annotated content, we combined the method of elastic-net regularization with the model-driven linear regression and the well-established data-driven independent component analysis (ICA) and inter-subject correlation (ISC) methods. In the linear regression analysis, both IC and region-of-interest (ROI) time-series were fitted with time-series of a total of 36 binary-valued and one real-valued tactile annotation of film features. The elastic-net regularization and cross-validation were applied in the ordinary least-squares linear regression in order to avoid over-fitting due to the multicollinearity of regressors, the results were compared against both the partial least-squares (PLS) regression and the un-regularized full-model regression. Non-parametric permutation testing scheme was applied to evaluate the statistical significance of regression. We found statistically significant correlation between the annotation model and 9 ICs out of 40 ICs. Regression analysis was also repeated for a large set of cubic ROIs covering the grey matter. Both IC- and ROI-based regression analyses revealed activations in parietal and occipital regions, with additional smaller clusters in the frontal lobe. Furthermore, we found elastic-net based regression more sensitive than PLS and un-regularized regression since it detected a larger number of significant ICs and ROIs. Along with the ISC ranking methods, our regression analysis proved

Auditory-visual stimulus pairing enhances perceptual learning in a songbird.

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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.

Behavioral performance follows the time course of neural facilitation and suppression during cued shifts of feature-selective attention.

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Andersen, S K; Müller, M M

2010-08-03

A central question in the field of attention is whether visual processing is a strictly limited resource, which must be allocated by selective attention. If this were the case, attentional enhancement of one stimulus should invariably lead to suppression of unattended distracter stimuli. Here we examine voluntary cued shifts of feature-selective attention to either one of two superimposed red or blue random dot kinematograms (RDKs) to test whether such a reciprocal relationship between enhancement of an attended and suppression of an unattended stimulus can be observed. The steady-state visual evoked potential (SSVEP), an oscillatory brain response elicited by the flickering RDKs, was measured in human EEG. Supporting limited resources, we observed both an enhancement of the attended and a suppression of the unattended RDK, but this observed reciprocity did not occur concurrently: enhancement of the attended RDK started at 220 ms after cue onset and preceded suppression of the unattended RDK by about 130 ms. Furthermore, we found that behavior was significantly correlated with the SSVEP time course of a measure of selectivity (attended minus unattended) but not with a measure of total activity (attended plus unattended). The significant deviations from a temporally synchronized reciprocity between enhancement and suppression suggest that the enhancement of the attended stimulus may cause the suppression of the unattended stimulus in the present experiment.

Resting state glutamate predicts elevated pre-stimulus alpha during self-relatedness: A combined EEG-MRS study on "rest-self overlap".

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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.

Stimulus-Elicited Connectivity Influences Resting-State Connectivity Years Later in Human Development: A Prospective Study.

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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

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.

Influence on Simon and SNARC Effects of a Nonspatial Stimulus-Response Mapping: Between-Task Logical Recoding

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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…

Does erotic stimulus presentation design affect brain activation patterns? Event-related vs. blocked fMRI designs.

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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.

Does erotic stimulus presentation design affect brain activation patterns? Event-related vs. blocked fMRI designs

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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.

Reliability in content analysis: The case of semantic feature norms classification.

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Bolognesi, Marianna; Pilgram, Roosmaryn; van den Heerik, Romy

2017-12-01

Semantic feature norms (e.g., STIMULUS: car → RESPONSE: ) are commonly used in cognitive psychology to look into salient aspects of given concepts. Semantic features are typically collected in experimental settings and then manually annotated by the researchers into feature types (e.g., perceptual features, taxonomic features, etc.) by means of content analyses-that is, by using taxonomies of feature types and having independent coders perform the annotation task. However, the ways in which such content analyses are typically performed and reported are not consistent across the literature. This constitutes a serious methodological problem that might undermine the theoretical claims based on such annotations. In this study, we first offer a review of some of the released datasets of annotated semantic feature norms and the related taxonomies used for content analysis. We then provide theoretical and methodological insights in relation to the content analysis methodology. Finally, we apply content analysis to a new dataset of semantic features and show how the method should be applied in order to deliver reliable annotations and replicable coding schemes. We tackle the following issues: (1) taxonomy structure, (2) the description of categories, (3) coder training, and (4) sustainability of the coding scheme-that is, comparison of the annotations provided by trained versus novice coders. The outcomes of the project are threefold: We provide methodological guidelines for semantic feature classification; we provide a revised and adapted taxonomy that can (arguably) be applied to both concrete and abstract concepts; and we provide a dataset of annotated semantic feature norms.

The transfer of social exclusion and inclusion functions through derived stimulus relations.

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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.

Amygdala Contributions to Stimulus-Reward Encoding in the Macaque Medial and Orbital Frontal Cortex during Learning.

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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

Compound stimulus extinction reduces spontaneous recovery in humans

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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.

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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.

Toward a Technology of Derived Stimulus Relations: An Analysis of Articles Published in the "Journal of Applied Behavior Analysis," 1992-2009

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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…

Exploring the Relation between Prenatal and Neonatal Complications and Later Autistic-Like Features in a Representative Community Sample of Twins

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Ronald, Angelica; Happe, Francesca; Dworzynski, Katharina; Bolton, Patrick; Plomin, Robert

2010-01-01

Prenatal and neonatal events were reported by parents of 13,690 eighteen-month-old twins enrolled in the Twins Early Development Study, a representative community sample born in England and Wales. At ages 7-8, parents and teachers completed questionnaires on social and nonsocial autistic-like features and parents completed the Childhood Asperger…

Neuronal representations of stimulus associations develop in the temporal lobe during learning.

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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.

Interactions between the spatial and temporal stimulus factors that influence multisensory integration in human performance.

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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.

Pupil responses and pain ratings to heat stimuli: Reliability and effects of expectations and a conditioning pain stimulus.

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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.

Clinical, neuropsychological, and pre-stimulus dorsomedial thalamic nucleus electrophysiological data in deep brain stimulation patients

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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

The effect of stimulus intensity on response time and accuracy in dynamic, temporally constrained environments.

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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.

Expectancy bias in a selective conditioning procedure: trait anxiety increases the threat value of a blocked stimulus

NARCIS (Netherlands)

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

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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

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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.

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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.

"in dem moment wo ich es dann erkenne dann ist es auch gleich wieder weg" – Salienzeffekte in der Sprachperzeption

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Christina Ada Anders

2014-06-01

Full Text Available In context of the first study on folk linguistic concepts in the German language area carried out by the Kiel DFG research project "perceptual dialectology", this article looks at how salient features could be surveyed and categorized by a stimulus-response-test. After a definition of salience, the study design including the stimulus-response-test is presented. The test was created and modified during the project as a guessing game by the Institute for German Language (IDS Mannheim. The central question in this article is which linguistic features stimulate the informants to locate a speech sample on a map with predetermined cities and hence which salient features trigger the regional identification. In a second step, the speech samples are analyzed by the variables 'pleasantness' and 'correctness' defined by Dennis R. Preston. The central question here is: Are speech samples with a high pleasure value also automatically considered correct? Finally, an interpretation of metalinguistic comments in the speech examples will give more insight into folk linguistic concepts and the role of salient features in this regard.

Primacy Performance of Normal and Retarded Children: Stimulus Familiarity or Spatial Memory?

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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)

Electrosensory Midbrain Neurons Display Feature Invariant Responses to Natural Communication Stimuli.

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Tristan Aumentado-Armstrong

2015-10-01

Full Text Available Neurons that respond selectively but in an invariant manner to a given feature of natural stimuli have been observed across species and systems. Such responses emerge in higher brain areas, thereby suggesting that they occur by integrating afferent input. However, the mechanisms by which such integration occurs are poorly understood. Here we show that midbrain electrosensory neurons can respond selectively and in an invariant manner to heterogeneity in behaviorally relevant stimulus waveforms. Such invariant responses were not seen in hindbrain electrosensory neurons providing afferent input to these midbrain neurons, suggesting that response invariance results from nonlinear integration of such input. To test this hypothesis, we built a model based on the Hodgkin-Huxley formalism that received realistic afferent input. We found that multiple combinations of parameter values could give rise to invariant responses matching those seen experimentally. Our model thus shows that there are multiple solutions towards achieving invariant responses and reveals how subthreshold membrane conductances help promote robust and invariant firing in response to heterogeneous stimulus waveforms associated with behaviorally relevant stimuli. We discuss the implications of our findings for the electrosensory and other systems.

Electrosensory Midbrain Neurons Display Feature Invariant Responses to Natural Communication Stimuli.

Science.gov (United States)

Aumentado-Armstrong, Tristan; Metzen, Michael G; Sproule, Michael K J; Chacron, Maurice J

2015-10-01

Neurons that respond selectively but in an invariant manner to a given feature of natural stimuli have been observed across species and systems. Such responses emerge in higher brain areas, thereby suggesting that they occur by integrating afferent input. However, the mechanisms by which such integration occurs are poorly understood. Here we show that midbrain electrosensory neurons can respond selectively and in an invariant manner to heterogeneity in behaviorally relevant stimulus waveforms. Such invariant responses were not seen in hindbrain electrosensory neurons providing afferent input to these midbrain neurons, suggesting that response invariance results from nonlinear integration of such input. To test this hypothesis, we built a model based on the Hodgkin-Huxley formalism that received realistic afferent input. We found that multiple combinations of parameter values could give rise to invariant responses matching those seen experimentally. Our model thus shows that there are multiple solutions towards achieving invariant responses and reveals how subthreshold membrane conductances help promote robust and invariant firing in response to heterogeneous stimulus waveforms associated with behaviorally relevant stimuli. We discuss the implications of our findings for the electrosensory and other systems.

Oscillatory Mechanisms of Stimulus Processing and Selection in the Visual and Auditory Systems: State-of-the-Art, Speculations and Suggestions

Directory of Open Access Journals (Sweden)

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.

Dissociable effects of inter-stimulus interval and presentation duration on rapid face categorization.

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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.

English semantic word-pair norms and a searchable Web portal for experimental stimulus creation.

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Buchanan, Erin M; Holmes, Jessica L; Teasley, Marilee L; Hutchison, Keith A

2013-09-01

As researchers explore the complexity of memory and language hierarchies, the need to expand normed stimulus databases is growing. Therefore, we present 1,808 words, paired with their features and concept-concept information, that were collected using previously established norming methods (McRae, Cree, Seidenberg, & McNorgan Behavior Research Methods 37:547-559, 2005). This database supplements existing stimuli and complements the Semantic Priming Project (Hutchison, Balota, Cortese, Neely, Niemeyer, Bengson, & Cohen-Shikora 2010). The data set includes many types of words (including nouns, verbs, adjectives, etc.), expanding on previous collections of nouns and verbs (Vinson & Vigliocco Journal of Neurolinguistics 15:317-351, 2008). We describe the relation between our and other semantic norms, as well as giving a short review of word-pair norms. The stimuli are provided in conjunction with a searchable Web portal that allows researchers to create a set of experimental stimuli without prior programming knowledge. When researchers use this new database in tandem with previous norming efforts, precise stimuli sets can be created for future research endeavors.

Agmatine attenuates the discriminative stimulus and hyperthermic effects of methamphetamine in male rats.

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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.

Stimulus-Driven Attention, Threat Bias, and Sad Bias in Youth with a History of an Anxiety Disorder or Depression.

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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.

Stimulus-driven attention, threat bias, and sad bias in youth with a history of an anxiety disorder or depression

Science.gov (United States)

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

Beauty at a glance: The feeling of beauty and the amplitude of pleasure are independent of stimulus duration.

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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.

Object-based selection from spatially-invariant representations: evidence from a feature-report task.

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Matsukura, Michi; Vecera, Shaun P

2011-02-01

Attention selects objects as well as locations. When attention selects an object's features, observers identify two features from a single object more accurately than two features from two different objects (object-based effect of attention; e.g., Duncan, Journal of Experimental Psychology: General, 113, 501-517, 1984). Several studies have demonstrated that object-based attention can operate at a late visual processing stage that is independent of objects' spatial information (Awh, Dhaliwal, Christensen, & Matsukura, Psychological Science, 12, 329-334, 2001; Matsukura & Vecera, Psychonomic Bulletin & Review, 16, 529-536, 2009; Vecera, Journal of Experimental Psychology: General, 126, 14-18, 1997; Vecera & Farah, Journal of Experimental Psychology: General, 123, 146-160, 1994). In the present study, we asked two questions regarding this late object-based selection mechanism. In Part I, we investigated how observers' foreknowledge of to-be-reported features allows attention to select objects, as opposed to individual features. Using a feature-report task, a significant object-based effect was observed when to-be-reported features were known in advance but not when this advance knowledge was absent. In Part II, we examined what drives attention to select objects rather than individual features in the absence of observers' foreknowledge of to-be-reported features. Results suggested that, when there was no opportunity for observers to direct their attention to objects that possess to-be-reported features at the time of stimulus presentation, these stimuli must retain strong perceptual cues to establish themselves as separate objects.

Anticipating Stimulus Money for Campus Projects, Colleges Get "Shovel Ready"

Science.gov (United States)

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…

Context-Dependent Modulation of Functional Connectivity: Secondary Somatosensory Cortex to Prefrontal Cortex Connections in Two-Stimulus-Interval Discrimination Tasks

OpenAIRE

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...

Isolating spectral cues in amplitude and quasi-frequency modulation discrimination by reducing stimulus duration.

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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.

Stimulus responsive hydrogel-coated etched fiber Bragg grating for carcinogenic chromium (VI) sensing

Science.gov (United States)

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.

Feature binding in visual short term memory: A General Recognition Theory analysis.

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Fitousi, Daniel

2017-05-23

Creating and maintaining accurate bindings of elementary features (e.g., color and shape) in visual short-term memory (VSTM) is fundamental for veridical perception. How are low-level features bound in memory? The present work harnessed a multivariate model of perception - the General Recognition Theory (GRT) - to unravel the internal representations underlying feature binding in VSTM. On each trial, preview and target colored shapes were presented in succession, appearing in either repeated or altered spatial locations. Participants gave two same/different responses: one with respect to color and one with respect to shape. Converging GRT analyses on the accuracy confusion matrices provided substantial evidence for binding in the form of violations of perceptual independence at the level of the individual stimulus, such that positive correlations were obtained when both features repeated or alternated together, while negative correlations were obtained when one feature repeated and the other alternated. This "cloverleaf" GRT pattern of binding was similar whether the spatial location of the preview and target repeated or altered. The current results are consistent with: (a) the discrete memory "slots" model of VSTM, and (b) the notion that spatial location is not necessary for the formation of "object files." The GRT approach presented here offers a viable quantitative model for testing various questions regarding feature binding in VSTM.

Prototypic Features of Loneliness in a Stratified Sample of Adolescents

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Mathias Lasgaard

2009-06-01

Full Text Available Dominant theoretical approaches in loneliness research emphasize the value of personality characteristics in explaining loneliness. The present study examines whether dysfunctional social strategies and attributions in lonely adolescents can be explained by personality characteristics. A questionnaire survey was conducted with 379 Danish Grade 8 students (M = 14.1 years, SD = 0.4 from 22 geographically stratified and randomly selected schools. Hierarchical linear regression analysis showed that network orientation, success expectation and avoidance in affiliative situations predicted loneliness independent of personality characteristics, demographics and social desirability. The study indicates that dysfunctional strategies and attributions in affiliative situations are directly related to loneliness in adolescence. These strategies and attributions may preclude lonely adolescents from guidance and intervention. Thus, professionals need to be knowledgeable about prototypic features of loneliness in addition to employing a pro-active approach when assisting adolescents who display prototypic features.

Distinct contributions of functional and deep neural network features to representational similarity of scenes in human brain and behavior.

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Groen, Iris Ia; Greene, Michelle R; Baldassano, Christopher; Fei-Fei, Li; Beck, Diane M; Baker, Chris I

2018-03-07

Inherent correlations between visual and semantic features in real-world scenes make it difficult to determine how different scene properties contribute to neural representations. Here, we assessed the contributions of multiple properties to scene representation by partitioning the variance explained in human behavioral and brain measurements by three feature models whose inter-correlations were minimized a priori through stimulus preselection. Behavioral assessments of scene similarity reflected unique contributions from a functional feature model indicating potential actions in scenes as well as high-level visual features from a deep neural network (DNN). In contrast, similarity of cortical responses in scene-selective areas was uniquely explained by mid- and high-level DNN features only, while an object label model did not contribute uniquely to either domain. The striking dissociation between functional and DNN features in their contribution to behavioral and brain representations of scenes indicates that scene-selective cortex represents only a subset of behaviorally relevant scene information.

Same/different concept learning by capuchin monkeys in matching-to-sample tasks.

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Valentina Truppa

Full Text Available The ability to understand similarities and analogies is a fundamental aspect of human advanced cognition. Although subject of considerable research in comparative cognition, the extent to which nonhuman species are capable of analogical reasoning is still debated. This study examined the conditions under which tufted capuchin monkeys (Cebus apella acquire a same/different concept in a matching-to-sample task on the basis of relational similarity among multi-item stimuli. We evaluated (i the ability of five capuchin monkeys to learn the same/different concept on the basis of the number of items composing the stimuli and (ii the ability to match novel stimuli after training with both several small stimulus sets and a large stimulus set. We found the first evidence of same/different relational matching-to-sample abilities in a New World monkey and demonstrated that the ability to match novel stimuli is within the capacity of this species. Therefore, analogical reasoning can emerge in monkeys under specific training conditions.

Same/Different Concept Learning by Capuchin Monkeys in Matching-to-Sample Tasks

Science.gov (United States)

Truppa, Valentina; Piano Mortari, Eva; Garofoli, Duilio; Privitera, Sara; Visalberghi, Elisabetta

2011-01-01

The ability to understand similarities and analogies is a fundamental aspect of human advanced cognition. Although subject of considerable research in comparative cognition, the extent to which nonhuman species are capable of analogical reasoning is still debated. This study examined the conditions under which tufted capuchin monkeys (Cebus apella) acquire a same/different concept in a matching-to-sample task on the basis of relational similarity among multi-item stimuli. We evaluated (i) the ability of five capuchin monkeys to learn the same/different concept on the basis of the number of items composing the stimuli and (ii) the ability to match novel stimuli after training with both several small stimulus sets and a large stimulus set. We found the first evidence of same/different relational matching-to-sample abilities in a New World monkey and demonstrated that the ability to match novel stimuli is within the capacity of this species. Therefore, analogical reasoning can emerge in monkeys under specific training conditions. PMID:21858225

Pre-stimulus BOLD-network activation modulates EEG spectral activity during working memory retention

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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.

Utilization of reward-prospect enhances preparatory attention and reduces stimulus conflict

NARCIS (Netherlands)

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.

Science.gov (United States)

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...

Pupil size reflects the focus of feature-based attention.

Science.gov (United States)

Binda, Paola; Pereverzeva, Maria; Murray, Scott O

2014-12-15

We measured pupil size in adult human subjects while they selectively attended to one of two surfaces, bright and dark, defined by coherently moving dots. The two surfaces were presented at the same location; therefore, subjects could select the cued surface only on the basis of its features. With no luminance change in the stimulus, we find that pupil size was smaller when the bright surface was attended and larger when the dark surface was attended: an effect of feature-based (or surface-based) attention. With the same surfaces at nonoverlapping locations, we find a similar effect of spatial attention. The pupil size modulation cannot be accounted for by differences in eye position and by other variables known to affect pupil size such as task difficulty, accommodation, or the mere anticipation (imagery) of bright/dark stimuli. We conclude that pupil size reflects not just luminance or cognitive state, but the interaction between the two: it reflects which luminance level in the visual scene is relevant for the task at hand. Copyright © 2014 the American Physiological Society.

Involvement of phosphorylated Apis mellifera CREB in gating a honeybee's behavioral response to an external stimulus

Science.gov (United States)

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

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.

Science.gov (United States)

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…

The relative importance of perceptual and memory sampling processes in determining the time course of absolute identification.

Science.gov (United States)

Guest, Duncan; Kent, Christopher; Adelman, James S

2018-04-01

In absolute identification, the extended generalized context model (EGCM; Kent & Lamberts, 2005, 2016) proposes that perceptual processing determines systematic response time (RT) variability; all other models of RT emphasize response selection processes. In the EGCM-RT the bow effect in RTs (longer responses for stimuli in the middle of the range) occurs because these middle stimuli are less isolated, and as perceptual information is accumulated, the evidence supporting a correct response grows more slowly than for stimuli at the ends of the range. More perceptual information is therefore accumulated in order to increase certainty in response for middle stimuli, lengthening RT. According to the model reducing perceptual sampling time should reduce the size of the bow effect in RT. We tested this hypothesis in 2 pitch identification experiments. Experiment 1 found no effect of stimulus duration on the size of the RT bow. Experiment 2 used multiple short stimulus durations as well as manipulating set size and stimulus spacing. Contrary to EGCM-RT predictions, the bow effect on RTs was large for even very short durations. A new version of the EGCM-RT could only capture this, alongside the effect of stimulus duration on accuracy, by including both a perceptual and a memory sampling process. A modified version of the selective attention, mapping, and ballistic accumulator model (Brown, Marley, Donkin, & Heathcote, 2008) could also capture the data, by assuming psychophysical noise diminishes with increased exposure duration. This modeling suggests systematic variability in RT in absolute identification is largely determined by memory sampling and response selection processes. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Human sensory-evoked responses differ coincident with either "fusion-memory" or "flash-memory", as shown by stimulus repetition-rate effects

Directory of Open Access Journals (Sweden)

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

Human sensory-evoked responses differ coincident with either "fusion-memory" or "flash-memory", as shown by stimulus repetition-rate effects

Science.gov (United States)

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

Code-modulated visual evoked potentials using fast stimulus presentation and spatiotemporal beamformer decoding.

Science.gov (United States)

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.

A novel L-band polarimetric radiometer featuring subharmonic sampling

DEFF Research Database (Denmark)

Rotbøll, J.; Søbjærg, Sten Schmidl; Skou, Niels

2003-01-01

A novel L-band radiometer trading analog components for digital circuits has been designed, built and operated. It is a fully polarimetric radiometer of the correlation type, and it is based on the subharmonic sampling principle in which the L-band signal is directly sampled by a fast A to D...

Robust preprocessing for stimulus-based functional MRI of the moving fetus.

Science.gov (United States)

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.

SSVEP recognition using common feature analysis in brain-computer interface.

Science.gov (United States)

Zhang, Yu; Zhou, Guoxu; Jin, Jing; Wang, Xingyu; Cichocki, Andrzej

2015-04-15

Canonical correlation analysis (CCA) has been successfully applied to steady-state visual evoked potential (SSVEP) recognition for brain-computer interface (BCI) application. Although the CCA method outperforms the traditional power spectral density analysis through multi-channel detection, it requires additionally pre-constructed reference signals of sine-cosine waves. It is likely to encounter overfitting in using a short time window since the reference signals include no features from training data. We consider that a group of electroencephalogram (EEG) data trials recorded at a certain stimulus frequency on a same subject should share some common features that may bear the real SSVEP characteristics. This study therefore proposes a common feature analysis (CFA)-based method to exploit the latent common features as natural reference signals in using correlation analysis for SSVEP recognition. Good performance of the CFA method for SSVEP recognition is validated with EEG data recorded from ten healthy subjects, in contrast to CCA and a multiway extension of CCA (MCCA). Experimental results indicate that the CFA method significantly outperformed the CCA and the MCCA methods for SSVEP recognition in using a short time window (i.e., less than 1s). The superiority of the proposed CFA method suggests it is promising for the development of a real-time SSVEP-based BCI. Copyright © 2014 Elsevier B.V. All rights reserved.

Poverty of the stimulus revisited.

Science.gov (United States)

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.

Auditory stimulus discrimination recorded in dogs, as indicated by mismatch negativity (MMN).

Science.gov (United States)

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.

Information about the model's unconditioned stimulus and response in vicarious classical conditioning.

Science.gov (United States)

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.

Stimulus rate dependence of regional cerebral blood flow in human striate cortex, demonstrated by positron emission tomography

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.

Science.gov (United States)

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.

Measurement of erythema and tanning responses in human skin using a tri-stimulus colorimeter.

Science.gov (United States)

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.

Behavioral performance follows the time course of neural facilitation and suppression during cued shifts of feature-selective attention

OpenAIRE

Andersen, S. K.; Müller, M. M.

2010-01-01

A central question in the field of attention is whether visual processing is a strictly limited resource, which must be allocated by selective attention. If this were the case, attentional enhancement of one stimulus should invariably lead to suppression of unattended distracter stimuli. Here we examine voluntary cued shifts of feature-selective attention to either one of two superimposed red or blue random dot kinematograms (RDKs) to test whether such a reciprocal relationship between enhanc...

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...

Decoupled choice-driven and stimulus-related activity in parietal neurons may be misrepresented by choice probabilities.

Science.gov (United States)

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).

The Possible Role of CO2 in Producing A Post-Stimulus CBF and BOLD Undershoot

Science.gov (United States)

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

Effect of stimulus parameters and contraction level on inhibitory responses in human jaw-closing muscles: Implications for contingent stimulation

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...

Stereotypical Escape Behavior in Caenorhabditis elegans Allows Quantification of Effective Heat Stimulus Level.

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.

Feature activation during word recognition: action, visual, and associative-semantic priming effects

Directory of Open Access Journals (Sweden)

Kevin J.Y. Lam

2015-05-01

Full Text Available Embodied theories of language postulate that language meaning is stored in modality-specific brain areas generally involved in perception and action in the real world. However, the temporal dynamics of the interaction between modality-specific information and lexical-semantic processing remain unclear. We investigated the relative timing at which two types of modality-specific information (action-based and visual-form information contribute to lexical-semantic comprehension. To this end, we applied a behavioral priming paradigm in which prime and target words were related with respect to (1 action features, (2 visual features, or (3 semantically associative information. Using a Go/No-Go lexical decision task, priming effects were measured across four different inter-stimulus intervals (ISI = 100 ms, 250 ms, 400 ms, and 1,000 ms to determine the relative time course of the different features . Notably, action priming effects were found in ISIs of 100 ms, 250 ms, and 1,000 ms whereas a visual priming effect was seen only in the ISI of 1,000 ms. Importantly, our data suggest that features follow different time courses of activation during word recognition. In this regard, feature activation is dynamic, measurable in specific time windows but not in others. Thus the current study (1 demonstrates how multiple ISIs can be used within an experiment to help chart the time course of feature activation and (2 provides new evidence for embodied theories of language.

An Appetitive Conditioned Stimulus Enhances Fear Acquisition and Impairs Fear Extinction

Science.gov (United States)

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.

Science.gov (United States)

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)

Feature-space-based FMRI analysis using the optimal linear transformation.

Science.gov (United States)

Sun, Fengrong; Morris, Drew; Lee, Wayne; Taylor, Margot J; Mills, Travis; Babyn, Paul S

2010-09-01

The optimal linear transformation (OLT), an image analysis technique of feature space, was first presented in the field of MRI. This paper proposes a method of extending OLT from MRI to functional MRI (fMRI) to improve the activation-detection performance over conventional approaches of fMRI analysis. In this method, first, ideal hemodynamic response time series for different stimuli were generated by convolving the theoretical hemodynamic response model with the stimulus timing. Second, constructing hypothetical signature vectors for different activity patterns of interest by virtue of the ideal hemodynamic responses, OLT was used to extract features of fMRI data. The resultant feature space had particular geometric clustering properties. It was then classified into different groups, each pertaining to an activity pattern of interest; the applied signature vector for each group was obtained by averaging. Third, using the applied signature vectors, OLT was applied again to generate fMRI composite images with high SNRs for the desired activity patterns. Simulations and a blocked fMRI experiment were employed for the method to be verified and compared with the general linear model (GLM)-based analysis. The simulation studies and the experimental results indicated the superiority of the proposed method over the GLM-based analysis in detecting brain activities.

The Personality Assessment Inventory as a proxy for the Psychopathy Checklist Revised: testing the incremental validity and cross-sample robustness of the Antisocial Features Scale.

Science.gov (United States)

Douglas, Kevin S; Guy, Laura S; Edens, John F; Boer, Douglas P; Hamilton, Jennine

2007-09-01

The Personality Assessment Inventory's (PAI's) ability to predict psychopathic personality features, as assessed by the Psychopathy Checklist-Revised (PCL-R), was examined. To investigate whether the PAI Antisocial Features (ANT) Scale and subscales possessed incremental validity beyond other theoretically relevant PAI scales, optimized regression equations were derived in a sample of 281 Canadian federal offenders. ANT, or ANT-Antisocial Behavior (ANT-A), demonstrated unique variance in regression analyses predicting PCL-R total and Factor 2 (Lifestyle Impulsivity and Social Deviance) scores, but only the Dominance (DOM) Scale was retained in models predicting Factor 1 (Interpersonal and Affective Deficits). Attempts to cross-validate the regression equations derived from the first sample on a sample of 85 U.S. sex offenders resulted in considerable validity shrinkage, with the ANT Scale in isolation performing comparably to or better than the statistical models for PCL-R total and Factor 2 scores. Results offer limited evidence of convergent validity between the PAI and the PCL-R.

Finite element modeling of the neuron-electrode interface: stimulus transfer and geometry

NARCIS (Netherlands)

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

The effects of compound stimulus extinction and inhibition of noradrenaline reuptake on the renewal of alcohol seeking

Science.gov (United States)

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

Performance effects of nicotine during selective attention, divided attention, and simple stimulus detection: an fMRI study.

Science.gov (United States)

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.

Effect of occlusal (mechanical) stimulus on bone remodelling in rat mandibular condyle.

Science.gov (United States)

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.

Can two dots form a Gestalt? Measuring emergent features with the capacity coefficient.

Science.gov (United States)

Hawkins, Robert X D; Houpt, Joseph W; Eidels, Ami; Townsend, James T

2016-09-01

While there is widespread agreement among vision researchers on the importance of some local aspects of visual stimuli, such as hue and intensity, there is no general consensus on a full set of basic sources of information used in perceptual tasks or how they are processed. Gestalt theories place particular value on emergent features, which are based on the higher-order relationships among elements of a stimulus rather than local properties. Thus, arbitrating between different accounts of features is an important step in arbitrating between local and Gestalt theories of perception in general. In this paper, we present the capacity coefficient from Systems Factorial Technology (SFT) as a quantitative approach for formalizing and rigorously testing predictions made by local and Gestalt theories of features. As a simple, easily controlled domain for testing this approach, we focus on the local feature of location and the emergent features of Orientation and Proximity in a pair of dots. We introduce a redundant-target change detection task to compare our capacity measure on (1) trials where the configuration of the dots changed along with their location against (2) trials where the amount of local location change was exactly the same, but there was no change in the configuration. Our results, in conjunction with our modeling tools, favor the Gestalt account of emergent features. We conclude by suggesting several candidate information-processing models that incorporate emergent features, which follow from our approach. Copyright © 2015 Elsevier Ltd. All rights reserved.

Sampling

CERN Document Server

Thompson, Steven K

2012-01-01

Praise for the Second Edition "This book has never had a competitor. It is the only book that takes a broad approach to sampling . . . any good personal statistics library should include a copy of this book." —Technometrics "Well-written . . . an excellent book on an important subject. Highly recommended." —Choice "An ideal reference for scientific researchers and other professionals who use sampling." —Zentralblatt Math Features new developments in the field combined with all aspects of obtaining, interpreting, and using sample data Sampling provides an up-to-date treat

Lever conditioned stimulus-directed autoshaping induced by saccharin-ethanol unconditioned stimulus solution: effects of ethanol concentration and trial spacing.

Science.gov (United States)

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

Nicotine as a discriminative stimulus for ethanol use.

Science.gov (United States)

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.

Stimulus-category competition, inhibition, and affective devaluation: a novel account of the uncanny valley.

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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

Stimulus-category competition, inhibition and affective devaluation: A novel account of the Uncanny Valley

Directory of Open Access Journals (Sweden)

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.

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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.

"Shovel-Ready" Data: The Stimulus Package and State Longitudinal Data Systems

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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

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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,…

A method for simultaneously counterbalancing condition order and assignment of stimulus materials to conditions.

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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.

Distinguishing stimulus and response codes in theta oscillations in prefrontal areas during inhibitory control of automated responses.

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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.

Autoshaping Chicks with Heat Reinforcement: The Role of Stimulus-Reinforcer and Response-Reinforcer Relations

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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)

A tactile stimulus applied to the leg improves postural stability in young, old and neuropathic subjects.

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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.

Laser sampling

International Nuclear Information System (INIS)

Gorbatenko, A A; Revina, E I

2015-01-01

The review is devoted to the major advances in laser sampling. The advantages and drawbacks of the technique are considered. Specific features of combinations of laser sampling with various instrumental analytical methods, primarily inductively coupled plasma mass spectrometry, are discussed. Examples of practical implementation of hybrid methods involving laser sampling as well as corresponding analytical characteristics are presented. The bibliography includes 78 references

Additive and Interactive Effects of Stimulus Degradation: No Challenge for CDP+

Science.gov (United States)

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

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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

OpenAIRE

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...

Chorionic villus sampling

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... medlineplus.gov/ency/article/003406.htm Chorionic villus sampling To use the sharing features on this page, please enable JavaScript. Chorionic villus sampling (CVS) is a test some pregnant women have ...

Separate representation of stimulus frequency, intensity, and duration in auditory sensory memory: an event-related potential and dipole-model analysis.

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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.

Optimizing the stimulus presentation paradigm design for the P300-based brain-computer interface using performance prediction.

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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

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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

Recent Visual Experience Shapes Visual Processing in Rats through Stimulus-Specific Adaptation and Response Enhancement.

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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.

Toward a technology of derived stimulus relations: an analysis of articles published in the journal of applied behavior analysis, 1992-2009.

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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.

Using non-feature films to teach diversity, cultural competence, and the DSM-IV-TR outline for cultural formulation.

Science.gov (United States)

Lim, Russell F; Diamond, Ronald J; Chang, Jacquelyn B; Primm, Annelle B; Lu, Francis G

2008-01-01

Feature films have been used for teaching in psychiatry for many years to demonstrate diagnoses, but the use of documentary and instructional films in resident and staff cultural competence training have not been extensively written about in the medical and psychological literature. This article will describe the films that have been used by the authors and suggest methods for their use in cultural competence and diversity training. A literature search was done using MEDLINE and PsychINFO and the authors were asked to describe their teaching methods. One article was found detailing the use of videotapes as a stimulus but not for cultural competence education, and two articles were found documenting the use of The Color of Fear as a stimulus for the discussion of racism. However, many educators use these films all across the country for the purpose of opening discussion about racism. Documentary, instructional, and public service announcements can be useful in teaching culturally competent assessment and treatment.

More than the Verbal Stimulus Matters: Visual Attention in Language Assessment for People with Aphasia Using Multiple-Choice Image Displays

Science.gov (United States)

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…

Evaluating Stability and Comparing Output of Feature Selectors that Optimize Feature Subset Cardinality

Czech Academy of Sciences Publication Activity Database

Somol, Petr; Novovičová, Jana

2010-01-01

Roč. 32, č. 11 (2010), s. 1921-1939 ISSN 0162-8828 R&D Projects: GA MŠk 1M0572; GA ČR GA102/08/0593; GA ČR GA102/07/1594 Grant - others:GA MŠk(CZ) 2C06019 Institutional research plan: CEZ:AV0Z10750506 Keywords : feature selection * feature stability * stability measures * similarity measures * sequential search * individual ranking * feature subset-size optimization * high dimensionality * small sample size Subject RIV: BD - Theory of Information Impact factor: 5.027, year: 2010 http://library.utia.cas.cz/separaty/2010/RO/somol-0348726.pdf

Does bimodal stimulus presentation increase ERP components usable in BCIs?

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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.

Recursive SVM feature selection and sample classification for mass-spectrometry and microarray data

Directory of Open Access Journals (Sweden)

Harris Lyndsay N

2006-04-01

Full Text Available Abstract Background Like microarray-based investigations, high-throughput proteomics techniques require machine learning algorithms to identify biomarkers that are informative for biological classification problems. Feature selection and classification algorithms need to be robust to noise and outliers in the data. Results We developed a recursive support vector machine (R-SVM algorithm to select important genes/biomarkers for the classification of noisy data. We compared its performance to a similar, state-of-the-art method (SVM recursive feature elimination or SVM-RFE, paying special attention to the ability of recovering the true informative genes/biomarkers and the robustness to outliers in the data. Simulation experiments show that a 5 %-~20 % improvement over SVM-RFE can be achieved regard to these properties. The SVM-based methods are also compared with a conventional univariate method and their respective strengths and weaknesses are discussed. R-SVM was applied to two sets of SELDI-TOF-MS proteomics data, one from a human breast cancer study and the other from a study on rat liver cirrhosis. Important biomarkers found by the algorithm were validated by follow-up biological experiments. Conclusion The proposed R-SVM method is suitable for analyzing noisy high-throughput proteomics and microarray data and it outperforms SVM-RFE in the robustness to noise and in the ability to recover informative features. The multivariate SVM-based method outperforms the univariate method in the classification performance, but univariate methods can reveal more of the differentially expressed features especially when there are correlations between the features.

Oscillatory Hierarchy Controlling Cortical Excitability and Stimulus Integration

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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.

Stimulus homogeneity enhances implicit learning: evidence from contextual cueing.

Science.gov (United States)

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

Different involvement of medial prefrontal cortex and dorso-lateral striatum in automatic and controlled processing of a future conditioned stimulus.

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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.

Cross-Domain Semi-Supervised Learning Using Feature Formulation.

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Xingquan Zhu

2011-12-01

Semi-Supervised Learning (SSL) traditionally makes use of unlabeled samples by including them into the training set through an automated labeling process. Such a primitive Semi-Supervised Learning (pSSL) approach suffers from a number of disadvantages including false labeling and incapable of utilizing out-of-domain samples. In this paper, we propose a formative Semi-Supervised Learning (fSSL) framework which explores hidden features between labeled and unlabeled samples to achieve semi-supervised learning. fSSL regards that both labeled and unlabeled samples are generated from some hidden concepts with labeling information partially observable for some samples. The key of the fSSL is to recover the hidden concepts, and take them as new features to link labeled and unlabeled samples for semi-supervised learning. Because unlabeled samples are only used to generate new features, but not to be explicitly included in the training set like pSSL does, fSSL overcomes the inherent disadvantages of the traditional pSSL methods, especially for samples not within the same domain as the labeled instances. Experimental results and comparisons demonstrate that fSSL significantly outperforms pSSL-based methods for both within-domain and cross-domain semi-supervised learning.

The rapid distraction of attentional resources toward the source of incongruent stimulus input during multisensory conflict.

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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.

Can Collateral Behavior Account for Transitions in the Stimulus Control of Speech?

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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…

The Effects of Different Training Structures in the Establishment of Conditional Discriminations and Subsequent Performance on Tests for Stimulus Equivalence

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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.…

SEEDLING DISCRIMINATION USING SHAPE FEATURES DERIVED FROM A DISTANCE TRANSFORM

DEFF Research Database (Denmark)

Mosgaard Giselsson, Thomas; Jørgensen, Rasmus Nyholm; Midtiby, Henrik

NN, Naive-Bayes, Linear SVM, Non-linear SVM). A set of well known features is used for comparison. This feature set will be referred to as Standard Feature Set (SFS). The used dataset consisted of 139 samples of Corn Flower (Centaura cyanus L.) and 63 samples of Night Shade (Solanum nigrum L.). The highest...

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.

Interactive Light Stimulus Generation with High Performance Real-Time Image Processing and Simple Scripting

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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.

Interactive Light Stimulus Generation with High Performance Real-Time Image Processing and Simple Scripting.

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