Effects of Shape-Discrimination Training on the Selectivity of Inferotemporal Cells in Adult Monkeys

1998 ◽  
Vol 80 (1) ◽  
pp. 324-330 ◽  
Author(s):  
Eucaly Kobatake ◽  
Gang Wang ◽  
Keiji Tanaka
Keyword(s):  
Discrimination Training ◽  
Neural Mechanisms ◽  
Visual Object ◽  
Shape Discrimination ◽  
Discrimination Ability ◽  
Cell Responses ◽  
Extensive Training ◽  
Complex Shapes ◽  
Visual Cortical ◽  
Area Te

Kobatake, Eucaly, Gang Wang, and Keiji Tanaka. Effects of shape-discrimination training on the selectivity of inferotemporal cells in adult monkeys. J. Neurophysiol. 80: 324–330, 1998. Through extensive training, humans can become “visual experts,” able to visually distinguish subtle differences among similar objects with greater ease than those who are untrained. To understand the neural mechanisms behind this acquired discrimination ability, adult monkeys were fully trained to discriminate 28 moderately complex shapes. The training effects on the stimulus selectivity of cells in area TE of the inferotemporal cortex were then examined in anesthetized preparations. Area TE represents a later stage of the ventral visual cortical pathway that is known to mediate visual object discrimination and recognition. The recordings from the trained monkeys and untrained controls showed that the proportion of TE cells responsive to some member of the 28 stimuli was significantly greater in the trained monkeys than that in the control monkeys. Cell responses recorded from the trained monkeys were not sharply tuned to single training stimuli, but rather broadly covered several training stimuli. The distances among the training stimuli in the response space spanned by responses of the recorded TE cells were significantly greater in the trained monkeys than those in the control monkeys. The subset of training stimuli to which individual cells responded differed from cell to cell with only partial overlaps, suggesting that the cells responded to features common to several stimuli. These results are consistent with a model in which visual expertise is acquired through the development of differential responses by inferotemporal cells to the images of relevant objects.

An Experiment on Shape Discrimination and Signal Detection in Octopus

1970 ◽  
Vol 22 (2) ◽  
pp. 82-90 ◽  
Author(s):  
W. R. A. Muntz
Keyword(s):  
Signal Detection ◽  
Discrimination Training ◽  
Roc Curve ◽  
Signal Detection Theory ◽  
Successive Discrimination ◽  
General Level ◽  
Original Training ◽  
Shape Discrimination ◽  
A Value ◽  
Vertical Bars

Ten octopuses were trained to perform a successive discrimination between the two shapes shown in Figure I (a). After 7 days of training, when performance was significantly above chance, transfer tests were given with other shapes that were either rotations or parts of the original training shapes. At least six theories have been put forward to explain shape discrimination in the octopus, but none of these are capable of explaining the present results. The transfer tests suggest that the discrimination was performed in terms of component parts of the shapes (vertical bars projecting upwards or downwards), and their relationship to the shape as a whole (terminal or central). During successive discrimination training the general level of attack varies between animals, and fluctuates from day to day. As a result there are often more attacks on both the positive and negative shapes on some occasions than others, making it difficult to compare the levels of discrimination achieved. It is suggested that the concepts of signal detection theory can help overcome this difficulty. Attacks on the positive shape (“hits”) plotted against attacks on the negative shape (“false positives”) constitute an ROC curve from which a value of d′, independant of the general level of attack, can be obtained.

Neural Mechanisms of Spatial Attention in the Visual Thalamus

2014 ◽  
Author(s):  
Yuri B. Saalmann ◽  
Sabine Kastner
Keyword(s):  
Selective Attention ◽  
Visual Information ◽  
Thalamic Nucleus ◽  
Sensory Information ◽  
Relevant Information ◽  
Neural Mechanisms ◽  
First Order ◽  
Visual Thalamus ◽  
Cortical Areas ◽  
Visual Cortical

Neural mechanisms of selective attention route behaviourally relevant information through brain networks for detailed processing. These attention mechanisms are classically viewed as being solely implemented in the cortex, relegating the thalamus to a passive relay of sensory information. However, this passive view of the thalamus is being revised in light of recent studies supporting an important role for the thalamus in selective attention. Evidence suggests that the first-order thalamic nucleus, the lateral geniculate nucleus, regulates the visual information transmitted from the retina to visual cortex, while the higher-order thalamic nucleus, the pulvinar, regulates information transmission between visual cortical areas, according to attentional demands. This chapter discusses how modulation of thalamic responses, switching the response mode of thalamic neurons, and changes in neural synchrony across thalamo-cortical networks contribute to selective attention.

scholarly journals Neural Mechanisms Underlying Visual Object Recognition

2014 ◽  
Vol 79 ◽  
pp. 99-107 ◽  
Author(s):  
Arash Afraz ◽  
Daniel L.K. Yamins ◽  
James J. DiCarlo
Keyword(s):  
Object Recognition ◽  
Neural Mechanisms ◽  
Visual Object ◽  
Visual Object Recognition

scholarly journals Temporal Encoding: Relative and absolute representations of time guide behavior

2020 ◽  
Author(s):  
Başak Akdoğan ◽  
Amita Wanar ◽  
Benjamin Kyle Gersten ◽  
Charles Randy Gallistel ◽  
Peter Balsam
Keyword(s):  
Temporal Discrimination ◽  
Duration Discrimination ◽  
Temporal Distance ◽  
Time Intervals ◽  
Discrimination Ability ◽  
Extensive Training ◽  
Discrimination Procedure ◽  
Directed Action ◽  
Temporal Encoding ◽  
Relational Control

Temporal information-processing is critical for adaptive behavior and goal-directed action. It is thus crucial to understand how the temporal distance between behaviorally relevant events is encoded to guide behavior. However, research on temporal representations has yielded mixed findings as to whether organisms utilize relative versus absolute judgments of time intervals. To address this fundamental question about the timing mechanism, we tested mice in a duration discrimination procedure in which they learned to correctly categorize tones of different durations as short or long. After being trained on a pair of target intervals the mice transferred to conditions in which cue durations and corresponding response locations were systematically manipulated. Specifically, responses and/or durations of cues were switched in different experimental phases so that either the relative or absolute mapping remained constant. The findings indicate that the transfer occurred most readily when relative relationships of durations and response locations were preserved. In contrast, when the animals had to re-map these relative relations, their temporal discrimination ability was impaired, and they required extensive training to re-establish temporal control. However, preserving the response location of one of the cue durations in such conditions was found to help with initial transfer. These results demonstrate that mice can represent experienced durations both as having a certain magnitude (absolute representation) and as being shorter or longer of the two durations (an ordinal relation to other cue durations), with relational control having a greater influence in temporal discriminations.

9.1: Invited Paper: Shape discrimination ability and disability glare in orthokeratology children

2019 ◽  
Vol 50 (S1) ◽  
pp. 86-86
Author(s):  
Jun Jiang ◽  
Binbin Su ◽  
Lin Zhou ◽  
Bin Zhang ◽  
Lv Fan
Keyword(s):  
Shape Discrimination ◽  
Discrimination Ability ◽  
Disability Glare

Haptic Shape Processing in Visual Cortex

2014 ◽  
Vol 26 (5) ◽  
pp. 1154-1167 ◽  
Author(s):  
Jacqueline C. Snow ◽  
Lars Strother ◽  
Glyn W. Humphreys
Keyword(s):  
Visual Cortex ◽  
Object Recognition ◽  
Primary Visual Cortex ◽  
Shape Recognition ◽  
Visual Object ◽  
Visual Object Recognition ◽  
Object Shape ◽  
Shape Processing ◽  
Shape Selective ◽  
Visual Cortical

Humans typically rely upon vision to identify object shape, but we can also recognize shape via touch (haptics). Our haptic shape recognition ability raises an intriguing question: To what extent do visual cortical shape recognition mechanisms support haptic object recognition? We addressed this question using a haptic fMRI repetition design, which allowed us to identify neuronal populations sensitive to the shape of objects that were touched but not seen. In addition to the expected shape-selective fMRI responses in dorsal frontoparietal areas, we observed widespread shape-selective responses in the ventral visual cortical pathway, including primary visual cortex. Our results indicate that shape processing via touch engages many of the same neural mechanisms as visual object recognition. The shape-specific repetition effects we observed in primary visual cortex show that visual sensory areas are engaged during the haptic exploration of object shape, even in the absence of concurrent shape-related visual input. Our results complement related findings in visually deprived individuals and highlight the fundamental role of the visual system in the processing of object shape.

scholarly journals Preparatory Encoding of the Fine Scale of Human Spatial Attention

2017 ◽  
Vol 29 (7) ◽  
pp. 1302-1310 ◽  
Author(s):  
Bradley Voytek ◽  
Jason Samaha ◽  
Camarin E. Rolle ◽  
Zachery Greenberg ◽  
Navdeep Gill ◽  
...  
Keyword(s):  
Target Location ◽  
Target Identification ◽  
Attentional Focus ◽  
Neural Mechanisms ◽  
Identification Accuracy ◽  
Scalp Eeg ◽  
Preparatory Period ◽  
Visual Cortical ◽  
Multivariate Pattern ◽  
Insight Into

Our attentional focus is constantly shifting: In one moment, our attention may be intently concentrated on a specific spot, whereas in another moment we might spread our attention more broadly. Although much is known about the mechanisms by which we shift our visual attention from place to place, relatively little is known about how we shift the aperture of attention from more narrowly to more broadly focused. Here we introduce a novel attentional distribution task to examine the neural mechanisms underlying this process. In this task, participants are presented with an informative cue that indicates the location of an upcoming target. This cue can be perfectly predictive of the exact target location, or it can indicate—with varying degrees of certainty—approximately where the target might appear. This cue is followed by a preparatory period in which there is nothing on the screen except a central fixation cross. Using scalp EEG, we examined neural activity during this preparatory period. We find that, with decreasing certainty regarding the precise location of the impending target, participant RTs increased whereas target identification accuracy decreased. Additionally, the multivariate pattern of preparatory period visual cortical alpha (8–12 Hz) activity encoded attentional distribution. This alpha encoding was predictive of behavioral accuracy and RT nearly 1 sec later. These results offer insight into the neural mechanisms underlying how we use information to guide our attentional distribution and how that influences behavior.

scholarly journals Preparatory encoding of the fine scale of human spatial attention

2016 ◽  
Author(s):  
Bradley Voytek ◽  
Jason Samaha ◽  
Camarin E. Rolle ◽  
Zachery Greenberg ◽  
Navdeep Gill ◽  
...  
Keyword(s):  
Visual Attention ◽  
Target Location ◽  
Academic Career ◽  
Attentional Focus ◽  
Neural Mechanisms ◽  
Identification Accuracy ◽  
University Of California ◽  
Grizzly Bear ◽  
Preparatory Period ◽  
Visual Cortical

AbstractOur attentional focus is constantly shifting: in one moment our vision may be intently concentrated on a specific spot, while in another moment we might spread our attention more broadly. While much is known about the mechanisms by which we shift our visual attention from place to place, relatively little is know about how we shift the aperture of attention from more narrowly-to more broadly-focused. Here we introduce a novel attentional distribution task to examine the neural mechanisms underlying this process. In this task, participants are presented with an informative cue that indicates the location of an upcoming target. This cue can be perfectly predictive of the exact target location, or it can indicate—with varying degrees of certainty—approximately where the target might appear. This cue is followed by a preparatory period in which there is nothing on the screen except a central fixation cross. Using scalp EEG, we examined neural activity during this preparatory period. We find that with decreasing certainty regarding the precise location of the impending target, participant response times increased while target identification accuracy decreased. Additionally, N1 amplitude in response to the cue parametrically increased with spatial certainty while the multivariate pattern of preparatory period visual cortical alpha (8-12 Hz) activity encoded attentional distribution. Both of these electrophysiological parameters were predictive of behavioral performance nearly one second later. These results offer insight into the neural mechanisms underlying how we use information to guide our attentional distribution, and how that influences behavior.Authors contributionsB.V. and A.G. conceived of the study; B.V. and A.G. designed the experimental task; B.V. and J.S. analyzed the EEG data; B.V., J.S., Z.G., N.G., S.P., T.K., S.R., and R.M. collected and analyzed behavioral data; all co-authors assisted in writing the manuscript.B.V. is funded by an NIH IRACDA (Institutional Research and Academic Career Development Award), a University of California Presidential Postdoctoral Fellowship, the University of California, San Diego CalIt2 Strategic Research Opportunities Program, and a Sloan Research Fellowship. A.G. is funded by the National Institutes of Health Grant R01-AG30395.Significant StatementAnimals—including humans—frequently shift their visual attentional focus more narrowly or broadly depending on expectations. For example, a predator feline may focus their visual attention on a burrow hole, waiting for their prey to emerge. In contrast, a grizzly bear hunting salmon doesn't know precisely where the fish will jump out of the water, so it must spread its attention more broadly. In a series of novel experiments, we show that this broadening of attention comes at a behavioral cost. We find that multivariate changes in preparatory visual cortical oscillatory alpha (8-12 Hz) encode attentional distribution. These results shed light on the potential neural mechanisms by which preparatory information is used to guide attentional focus.

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