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Cross-Modal Multivariate Pattern Analysis
Published on: November 9, 2011
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Dynamic gamma frequency feedback coupling between higher and lower order visual cortices underlies perceptual
S Moratti1, C Méndez-Bértolo2, F Del-Pozo3
1Department of Basic Psychology I, Complutense University of Madrid (UCM), 28223 Pozuelo de Alarcón, Madrid, Spain; Laboratory for Clinical Neuroscience, Centre for Biomedical Technology, Technical University of Madrid (UPM), Campus Montegancedo, 28223 Pozuelo de Alarcón, Madrid, Spain.
Neuroimage
|November 5, 2013
Summary
Gestalt formation, or perceptual completion, involves brain oscillations and top-down feedback. Gamma oscillations in visual cortices show reciprocal coupling, with feedback modulating early visual processing for coherent perception.
Area of Science:
- Neuroscience
- Cognitive Science
- Visual Perception
Background:
- Perceptual completion integrates incomplete visual forms into coherent percepts, a process known as Gestalt formation.
- This process is thought to involve oscillatory neuronal activity in distributed brain networks.
- Evidence suggests top-down feedback from higher brain regions to early visual cortex is crucial for Gestalt formation.
Purpose of the Study:
- To investigate the effective coupling between sources of oscillatory brain activity during Gestalt formation.
- To elucidate the role of top-down feedback in perceptual completion using magnetoencephalography (MEG).
Main Methods:
- Magnetoencephalography (MEG) was employed to record brain activity.
- Effective connectivity analysis in the frequency domain was used to assess neuronal coupling.
- Participants viewed two-tone 'Mooney' faces to elicit perceptual completion.
Main Results:
- Perceptual completion of Mooney faces increased gamma frequency band power (55-71Hz) in early visual, fusiform, and parietal cortices.
- Fusiform and parietal gamma oscillators exhibited coupled forward and backward connectivity, indicating reciprocal influences.
- Early visual cortex gamma oscillations were modulated by top-down feedback from fusiform and parietal cortices.
Conclusions:
- Gestalt perception involves reciprocal gamma oscillations between higher-order visual areas (fusiform, parietal) and early visual cortex.
- Top-down feedback from fusiform and parietal cortices plays a critical role in modulating gamma activity in early visual processing.
- These findings support a model of inverse hierarchical processing in the visual system for generating coherent percepts.
Keywords:
Dynamic causal modelsFeedbackGamma band activityPerceptual completionReverse hierarchical visual processingMore Related Videos
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