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06:02
Topographical Estimation of Visual Population Receptive Fields by fMRI
Published on: February 3, 2015
An illusion predicted by V1 population activity implicates cortical topography in shape perception.
Melchi M Michel1, Yuzhi Chen, Wilson S Geisler
1Department of Psychology, Rutgers University, New Brunswick, New Jersey, USA.
Nature Neuroscience
|September 17, 2013
Summary
The brain's visual cortex topography influences shape perception. Neural activity spread in the primary visual cortex (V1) creates illusions, showing its role in how we see shapes.
Area of Science:
- Neuroscience
- Computational Neuroscience
- Visual Perception
Background:
- Mammalian primary visual cortex (V1) exhibits topographic organization, mapping visual field locations to specific neural areas.
- The precise contribution of this large-scale V1 topography to conscious visual perception, particularly shape judgments, remains poorly understood.
Purpose of the Study:
- To investigate whether the topographic organization of V1 population responses influences human shape perception.
- To determine if the spatial spread of neural activity in V1 can systematically distort visual shape judgments.
Main Methods:
- Utilized computational modeling to design visual stimuli with identical physical shapes but predicted to evoke differential V1 response spread.
- Employed voltage-sensitive dye imaging (VSDI) in behaving monkeys to experimentally confirm predicted V1 activity patterns.
- Conducted behavioral experiments with human observers judging the shapes of these stimuli.
Main Results:
- Computational models successfully predicted variable V1 response spread for physically identical shapes.
- VSDI confirmed that designed stimuli elicited the predicted differences in the spatial spread of neural activity in V1.
- Human observers' shape judgments were systematically biased by the V1 activity spread, creating a perceptual illusion.
Conclusions:
- The topographic pattern of neural population responses in V1 directly influences visual perception.
- V1 activity spread, not just the physical stimulus, plays a crucial role in how we perceive shape.
- This study provides evidence for the perceptual relevance of V1's large-scale neural organization.
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