scholarly journals Stimulus predictability affects reconstruction of dynamic visual objects in early visual cortex

2018 ◽  
Vol 18 (10) ◽  
pp. 347
Author(s):  
Sunyoung Park ◽  
Won Mok Shim
Keyword(s):  
Visual Cortex ◽  
Visual Objects ◽  
Early Visual Cortex

scholarly journals Increasing suppression of saccade-related transients along the human visual hierarchy

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Tal Golan ◽  
Ido Davidesco ◽  
Meir Meshulam ◽  
David M Groppe ◽  
Pierre Mégevand ◽  
...  
Keyword(s):  
Visual Cortex ◽  
High Frequency ◽  
Large Individual ◽  
Perceptual Awareness ◽  
Eye Blinks ◽  
Visual Objects ◽  
Visual Hierarchy ◽  
Neurosurgical Patients ◽  
Early Visual Cortex ◽  
High Frequency Activity

A key hallmark of visual perceptual awareness is robustness to instabilities arising from unnoticeable eye and eyelid movements. In previous human intracranial (iEEG) work (Golan et al., 2016) we found that excitatory broadband high-frequency activity transients, driven by eye blinks, are suppressed in higher-level but not early visual cortex. Here, we utilized the broad anatomical coverage of iEEG recordings in 12 eye-tracked neurosurgical patients to test whether a similar stabilizing mechanism operates following small saccades. We compared saccades (1.3°−3.7°) initiated during inspection of large individual visual objects with similarly-sized external stimulus displacements. Early visual cortex sites responded with positive transients to both conditions. In contrast, in both dorsal and ventral higher-level sites the response to saccades (but not to external displacements) was suppressed. These findings indicate that early visual cortex is highly unstable compared to higher-level visual regions which apparently constitute the main target of stabilizing extra-retinal oculomotor influences.

scholarly journals Increasing suppression of saccade-related transients along the human visual hierarchy

2017 ◽  
Author(s):  
Tal Golan ◽  
Ido Davidesco ◽  
Meir Meshulam ◽  
David M Groppe ◽  
Pierre Mégevand ◽  
...  
Keyword(s):  
Visual Cortex ◽  
High Frequency ◽  
Large Individual ◽  
Perceptual Awareness ◽  
Eye Blinks ◽  
Visual Objects ◽  
Visual Hierarchy ◽  
Neurosurgical Patients ◽  
Early Visual Cortex ◽  
High Frequency Activity

AbstractA key hallmark of visual perceptual awareness is robustness to instabilities arising from unnoticeable eye and eyelid movements. In previous human intracranial (iEEG) work (Golan et al., 2016) we found that excitatory broadband high-frequency activity transients, driven by eye blinks, are suppressed in higher-level but not early visual cortex. Here, we utilized the broad anatomical coverage of iEEG recordings in 12 eye-tracked neurosurgical patients to test whether a similar stabilizing mechanism operates following small saccades. We compared saccades (1.3°-3.7°) initiated during inspection of large individual visual objects with similarly-sized external stimulus displacements. Early visual cortex sites responded with positive transients to both conditions. In contrast, in both dorsal and ventral higher-level sites the response to saccades (but not to external displacements) was suppressed. These findings indicate that early visual cortex is highly unstable compared to higher-level visual regions which apparently constitute the main target of stabilizing extra-retinal oculomotor influences.

scholarly journals Reconstructing representations of dynamic visual objects in early visual cortex

2015 ◽  
Vol 113 (5) ◽  
pp. 1453-1458 ◽  
Author(s):  
Edmund Chong ◽  
Ariana M. Familiar ◽  
Won Mok Shim
Keyword(s):  
Visual Cortex ◽  
Population Level ◽  
Neural Representation ◽  
Test Case ◽  
Missing Information ◽  
Sensory Data ◽  
Visual Objects ◽  
Retinal Input ◽  
Early Visual Cortex ◽  
Object Features

As raw sensory data are partial, our visual system extensively fills in missing details, creating enriched percepts based on incomplete bottom-up information. Despite evidence for internally generated representations at early stages of cortical processing, it is not known whether these representations include missing information of dynamically transforming objects. Long-range apparent motion (AM) provides a unique test case because objects in AM can undergo changes both in position and in features. Using fMRI and encoding methods, we found that the “intermediate” orientation of an apparently rotating grating, never presented in the retinal input but interpolated during AM, is reconstructed in population-level, feature-selective tuning responses in the region of early visual cortex (V1) that corresponds to the retinotopic location of the AM path. This neural representation is absent when AM inducers are presented simultaneously and when AM is visually imagined. Our results demonstrate dynamic filling-in in V1 for object features that are interpolated during kinetic transformations.

scholarly journals Decoding the future from past experience: learning shapes predictions in early visual cortex

2015 ◽  
Vol 113 (9) ◽  
pp. 3159-3171 ◽  
Author(s):  
Caroline D. B. Luft ◽  
Alan Meeson ◽  
Andrew E. Welchman ◽  
Zoe Kourtzi
Keyword(s):  
Visual Cortex ◽  
Large Scale ◽  
Sequence Structure ◽  
Neural Populations ◽  
Early Visual Cortex ◽  
Temporal Structures ◽  
Future Events ◽  
Sensory Predictions ◽  
Actual Stimulus ◽  
The Brain

Learning the structure of the environment is critical for interpreting the current scene and predicting upcoming events. However, the brain mechanisms that support our ability to translate knowledge about scene statistics to sensory predictions remain largely unknown. Here we provide evidence that learning of temporal regularities shapes representations in early visual cortex that relate to our ability to predict sensory events. We tested the participants' ability to predict the orientation of a test stimulus after exposure to sequences of leftward- or rightward-oriented gratings. Using fMRI decoding, we identified brain patterns related to the observers' visual predictions rather than stimulus-driven activity. Decoding of predicted orientations following structured sequences was enhanced after training, while decoding of cued orientations following exposure to random sequences did not change. These predictive representations appear to be driven by the same large-scale neural populations that encode actual stimulus orientation and to be specific to the learned sequence structure. Thus our findings provide evidence that learning temporal structures supports our ability to predict future events by reactivating selective sensory representations as early as in primary visual cortex.

scholarly journals Reinstatement of Associative Memories in Early Visual Cortex Is Signaled by the Hippocampus

2014 ◽  
Vol 34 (22) ◽  
pp. 7493-7500 ◽  
Author(s):  
S. E. Bosch ◽  
J. F. M. Jehee ◽  
G. Fernandez ◽  
C. F. Doeller
Keyword(s):  
Visual Cortex ◽  
Associative Memories ◽  
Early Visual Cortex

Timing of activity in early visual cortex as revealed by transcranial magnetic stimulation

Neuroreport ◽  
1999 ◽  
Vol 10 (12) ◽  
pp. 2631-2634 ◽  
Author(s):  
Erik Corthout ◽  
Bob Uttl ◽  
Vincent Walsh ◽  
Mark Hallett ◽  
Alan Cowey
Keyword(s):  
Visual Cortex ◽  
Transcranial Magnetic Stimulation ◽  
Magnetic Stimulation ◽  
Early Visual Cortex

scholarly journals Preparatory Activity in Posterior Temporal Cortex Causally Contributes to Object Detection in Scenes

2015 ◽  
Vol 27 (11) ◽  
pp. 2117-2125 ◽  
Author(s):  
Reshanne R. Reeder ◽  
Francesca Perini ◽  
Marius V. Peelen
Keyword(s):  
Visual Cortex ◽  
Object Detection ◽  
Activity Patterns ◽  
Temporal Cortex ◽  
Relevant Information ◽  
Visual Selective Attention ◽  
Object Categories ◽  
Preparatory Attention ◽  
Preparatory Activity ◽  
Early Visual Cortex

Theories of visual selective attention propose that top–down preparatory attention signals mediate the selection of task-relevant information in cluttered scenes. Neuroimaging and electrophysiology studies have provided correlative evidence for this hypothesis, finding increased activity in target-selective neural populations in visual cortex in the period between a search cue and target onset. In this study, we used online TMS to test whether preparatory neural activity in visual cortex is causally involved in naturalistic object detection. In two experiments, participants detected the presence of object categories (cars, people) in a diverse set of photographs of real-world scenes. TMS was applied over a region in posterior temporal cortex identified by fMRI as carrying category-specific preparatory activity patterns. Results showed that TMS applied over posterior temporal cortex before scene onset (−200 and −100 msec) impaired the detection of object categories in subsequently presented scenes, relative to vertex and early visual cortex stimulation. This effect was specific to category level detection and was related to the type of attentional template participants adopted, with the strongest effects observed in participants adopting category level templates. These results provide evidence for a causal role of preparatory attention in mediating the detection of objects in cluttered daily-life environments.

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