scholarly journals Columnar Neural Mechanisms Underlying Vertically Asymmetric Global Visual Processing

2018 ◽  
Vol 18 (10) ◽  
pp. 122
Author(s):  
shahin nasr ◽  
Roger Tootell
Keyword(s):  
Visual Processing ◽  
Neural Mechanisms

Repetition Suppression of Induced Gamma Activity Predicts Enhanced Orienting toward a Novel Stimulus in 6-month-old Infants

2008 ◽  
Vol 20 (12) ◽  
pp. 2137-2152 ◽  
Author(s):  
Kelly A. Snyder ◽  
Andreas Keil
Keyword(s):  
Visual Processing ◽  
Novelty Detection ◽  
Neural Mechanisms ◽  
Human Infant ◽  
Gamma Activity ◽  
Repeated Stimulus ◽  
Repetition Suppression ◽  
The Face ◽  
Over 40 Years

Habituation refers to a decline in orienting or responding to a repeated stimulus, and can be inferred to reflect learning about the properties of the repeated stimulus when followed by increased orienting to a novel stimulus (i.e., novelty detection). Habituation and novelty detection paradigms have been used for over 40 years to study perceptual and mnemonic processes in the human infant, yet important questions remain about the nature of these processes in infants. The aim of the present study was to examine the neural mechanisms underlying habituation and novelty detection in infants. Specifically, we investigated changes in induced alpha, beta, and gamma activity in 6-month-old infants during repeated presentations of either a face or an object, and examined whether these changes predicted behavioral responses to novelty at test. We found that induced gamma activity over occipital scalp regions decreased with stimulus repetition in the face condition but not in the toy condition, and that greater decreases in the gamma band were associated with enhanced orienting to a novel face at test. The pattern and topography of these findings are consistent with observations of repetition suppression in the occipital–temporal visual processing pathway, and suggest that encoding in infant habituation paradigms may reflect a form of perceptual learning. Implications for the role of repetition suppression in infant habituation and novelty detection are discussed with respect to a biased competition model of visual attention.

Two distinct neural mechanisms in early visual cortex determine subsequent visual processing

Cortex ◽  
2014 ◽  
Vol 59 ◽  
pp. 1-11 ◽  
Author(s):  
Christianne Jacobs ◽  
Tom A. de Graaf ◽  
Alexander T. Sack
Keyword(s):  
Visual Cortex ◽  
Visual Processing ◽  
Neural Mechanisms ◽  
Early Visual Cortex

scholarly journals The neural mechanism of aesthetic judgments of dynamic landscapes: an fMRI study

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Xueru Zhao ◽  
Junjing Wang ◽  
Jinhui Li ◽  
Guang Luo ◽  
Ting Li ◽  
...  
Keyword(s):  
Visual Processing ◽  
Occipital Lobe ◽  
Neural Mechanism ◽  
Aesthetic Judgment ◽  
Neural Mechanisms ◽  
Middle Temporal Gyrus ◽  
Dynamic Stimuli ◽  
Dynamic Landscapes ◽  
The Aesthetic ◽  
Aesthetic Judgments

AbstractMost previous neuroaesthetics research has been limited to considering the aesthetic judgment of static stimuli, with few studies examining the aesthetic judgment of dynamic stimuli. The present study explored the neural mechanisms underlying aesthetic judgment of dynamic landscapes, and compared the neural mechanisms between the aesthetic judgments of dynamic landscapes and static ones. Participants were scanned while they performed aesthetic judgments on dynamic landscapes and matched static ones. The results revealed regions of occipital lobe, frontal lobe, supplementary motor area, cingulate cortex and insula were commonly activated both in the aesthetic judgments of dynamic and static landscapes. Furthermore, compared to static landscapes, stronger activations of middle temporal gyrus (MT/V5), and hippocampus were found in the aesthetic judgments of dynamic landscapes. This study provided neural evidence that visual processing related regions, emotion-related regions were more active when viewing dynamic landscapes than static ones, which also indicated that dynamic stimuli were more beautiful than static ones.

Effects of Neural Mechanisms of Pretask Resting EEG Alpha Information on Situational Awareness: A Functional Connectivity Approach

2019 ◽  
Vol 62 (7) ◽  
pp. 1150-1170 ◽  
Author(s):  
Ardaman Kaur ◽  
Rishu Chaujar ◽  
Vijayakumar Chinnadurai
Keyword(s):  
Reaction Time ◽  
Functional Connectivity ◽  
Visual Processing ◽  
Emotional Regulation ◽  
Stroop Effect ◽  
Situational Awareness ◽  
Strong Association ◽  
Neural Mechanisms ◽  
Emotion And Memory ◽  
Neural Underpinnings

Objective In this study, the influence of pretask resting neural mechanisms on situational awareness (SA)-task is studied. Background Pretask electroencephalography (EEG) information and Stroop effect are known to influence task engagement independently. However, neural mechanisms of pretask resting absolute alpha (PRAA) and pretask resting alpha frontal asymmetry (PRAFA) in influencing SA-task which is undergoing Stroop effect is still not understood. Method The study involved pretask resting EEG measurements from 18 healthy individuals followed by functional magnetic resonance imaging (fMRI) acquisition during SA-task. To understand the effect of pretask alpha information and Stroop effect on SA, a robust correlation between mean reaction time, SA Index, PRAA, and PRAFA were assessed. Furthermore, neural underpinnings of PRAA, PRAFA in SA-task, and functional connectivity were analyzed through the EEG-informed fMRI approach. Results Significant robust correlation of reaction time was observed with SA Index (Pearson: r = .50, pcorr = .05) and PRAFA (Pearson: r = .63; pcorr = .01), respectively. Similarly, SA Index significantly correlated with PRAFA (Pearson: r = .56, pcorr = .01; Spearman: r = .61, pcorr = .007), and PRAA (Pearson: r = .59, pcorr = .005; Spearman: r = .59, pcorr = .002). Neural underpinnings of SA-task revealed regions involved in visual-processing and higher-order cognition. PRAA was primarily underpinned at frontal-temporal areas and functionally connected to SA-task regions pertaining to the emotional regulation. PRAFA has correlated with limbic and parietal regions, which are involved in integration of visual, emotion, and memory information of SA-task. Conclusion The results suggest a strong association of reaction time with SA-task and PRAFA and strongly support the hypothesis that PRAFA, PRAA, and associated neural mechanisms significantly influence the outcome of SA-task. Application It is beneficial to study the effect of pretask resting information on SA-task to improve SA.

scholarly journals Human-level saccade detection performance using deep neural networks

2018 ◽  
Author(s):  
Marie E. Bellet ◽  
Joachim Bellet ◽  
Hendrikje Nienborg ◽  
Ziad M. Hafed ◽  
Philipp Berens
Keyword(s):  
Eye Movements ◽  
Cognitive Processes ◽  
Visual Processing ◽  
Performance Metrics ◽  
Visual Space ◽  
Neural Mechanisms ◽  
Eye Tracker ◽  
Noise Levels ◽  
Performance Accuracy ◽  
Level Performance

Saccades are ballistic eye movements that rapidly shift gaze from one location of visual space to another. Detecting saccades in eye movement recordings is important not only for studying the neural mechanisms underlying sensory, motor, and cognitive processes, but also as a clinical and diagnostic tool. However, automatically detecting saccades can be difficult, particularly when such saccades are generated in coordination with other tracking eye movements, like smooth pursuits, or when the saccade amplitude is close to eye tracker noise levels, like with microsaccades. In such cases, labeling by human experts is required, but this is a tedious task prone to variability and error. We developed a convolutional neural network (CNN) to automatically detect saccades at human-level performance accuracy. Our algorithm surpasses state of the art according to common performance metrics, and will facilitate studies of neurophysiological processes underlying saccade generation and visual processing.

Learning

2011 ◽  
pp. 41-58
Author(s):  
Frank van der Velde
Keyword(s):  
Animal Models ◽  
Associative Learning ◽  
Experimental Research ◽  
Animal Behavior ◽  
Visual Processing ◽  
Visual Learning ◽  
Complex Form ◽  
Neural Mechanisms ◽  
Complex Forms

This chapter reviews research into human and animal forms of learning. It concentrates on two forms of learning in particular. The first is conditioning. The study of conditioning constitutes the first example of experimental research on learning. At first, it seemed to corroborate the view that learning consists of establishing associations. This form of learning was proposed by the early empiricists. The notion of associative learning influenced the emergence of behaviorism, which used conditioning to account for all forms of human and animal behavior. More recent research, however, has shown that conditioning is a more complex form of learning, related to propositional learning. This makes conditioning important for the study of the mechanisms of other, more complex, forms of propositional learning, as found in language and reasoning. The second form of learning reviewed here is visual learning. The study of this form of learning is important for understanding visual processing. And it is important for investigating the neural mechanisms of learning, given the availability of animal models of visual processing.

Biophysiologically Plausible Implementations of the Maximum Operation

2002 ◽  
Vol 14 (12) ◽  
pp. 2857-2881 ◽  
Author(s):  
Angela J. Yu ◽  
Martin A. Giese ◽  
Tomaso A. Poggio
Keyword(s):  
Mathematical Analysis ◽  
Visual Processing ◽  
Brain Regions ◽  
Neural Mechanisms ◽  
Hierarchical Architecture ◽  
Visual Features ◽  
Cortical Processing ◽  
Canonical Models ◽  
Stimulus Properties ◽  
Processing Pathways

Visual processing in the cortex can be characterized by a predominantly hierarchical architecture, in which specialized brain regions along the processing pathways extract visual features of increasing complexity, accompanied by greater invariance in stimulus properties such as size and position. Various studies have postulated that a nonlinear pooling function such as the maximum (MAX) operation could be fundamental in achieving such selectivity and invariance. In this article, we are concerned with neurally plausible mechanisms that may be involved in realizing the MAX operation. Different canonical models are proposed, each based on neural mechanisms that have been previously discussed in the context of cortical processing. Through simulations and mathematical analysis, we compare the performance and robustness of these mechanisms. We derive experimentally verifiable predictions for each model and discuss the relevant physiological considerations.

scholarly journals Neural Correlates of Metamemory: A Comparison of Feeling-of-Knowing and Retrospective Confidence Judgments

2009 ◽  
Vol 21 (9) ◽  
pp. 1751-1765 ◽  
Author(s):  
Elizabeth F. Chua ◽  
Daniel L. Schacter ◽  
Reisa A. Sperling
Keyword(s):  
Neural Activity ◽  
Visual Processing ◽  
Memory Retrieval ◽  
Medial Temporal Lobe ◽  
Neural Correlates ◽  
Neural Mechanisms ◽  
Multiple Forms ◽  
Functional Roles ◽  
Feeling Of Knowing ◽  
Metamemory Monitoring

Metamemory refers to knowledge and monitoring of one's own memory. Metamemory monitoring can be done prospectively with respect to subsequent memory retrieval or retrospectively with respect to previous memory retrieval. In this study, we used fMRI to compare neural activity during prospective feeling-of-knowing and retrospective confidence tasks in order to examine common and distinct mechanisms supporting multiple forms of metamemory monitoring. Both metamemory tasks, compared to non-metamemory tasks, were associated with greater activity in medial prefrontal, medial parietal, and lateral parietal regions, which have previously been implicated in internally directed cognition. Furthermore, compared to non-metamemory tasks, metamemory tasks were associated with less activity in occipital regions, and in lateral inferior frontal and dorsal medial prefrontal regions, which have previously shown involvement in visual processing and stimulus-oriented attention, respectively. Thus, neural activity related to metamemory is characterized by both a shift toward internally directed cognition and away from externally directed cognition. Several regions demonstrated differences in neural activity between feeling-of-knowing and confidence tasks, including fusiform, medial temporal lobe, and medial parietal regions; furthermore, these regions also showed interaction effects between task and the subjective metamemory rating, suggesting that they are sensitive to the information monitored in each particular task. These findings demonstrate both common and distinct neural mechanisms supporting metamemory processes and also serve to elucidate the functional roles of previously characterized brain networks.

Fine Discrimination of Faces can be Performed Rapidly

2000 ◽  
Vol 12 (5) ◽  
pp. 848-855 ◽  
Author(s):  
Sidney R. Lehky
Keyword(s):  
Principal Components ◽  
Visual Processing ◽  
Visual Pathways ◽  
Neural Mechanisms ◽  
Just Noticeable Difference ◽  
Computational Algorithms ◽  
Average Difference ◽  
Tiny Amount ◽  
Test Face ◽  
Behavioral Evidence

Here we measure the smallest change in a face that can be discriminated. A morphing algorithm mixed two faces in variable proportions to create a series of synthetic faces that each differed by a tiny amount. By selecting from this series, a test face could be chosen so as to reach a just noticeable difference from a sample face. Face-discrimination thresholds were about 7% of the average difference between two faces, as quantified by coefficients of a principal components decomposition. This threshold remained constant as the duration of the test face was reduced from 1,000 to 100 msec, and rose quickly for shorter stimulus durations. The behavioral evidence presented here indicates that complex visual processing can be completed within the first 100 msec of the signal, suggesting involvement of feedforward neural mechanisms, and placing constraints on possible computational algorithms employed within the ventral visual pathways.

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