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Methods to Explore the Influence of Top-down Visual Processes on Motor Behavior
Published on: April 16, 2014
Viewed actions are mapped in retinotopic coordinates in the human visual pathways.
Yuval Porat1, Yoni Pertzov, Ehud Zohary
1Department of Neurobiology, Hebrew University, Jerusalem, Israel. yporat@gmail.com
Journal of Vision
|October 25, 2011
Summary
Viewed object-oriented actions are processed in retinotopic coordinates, not spatiotopic ones. This finding from fMRI studies suggests the brain maintains visual information relative to the retina.
Area of Science:
- Neuroscience
- Cognitive Neuroscience
- Visual Perception
Background:
- Object-oriented actions activate visual pathways, typically stronger in the contralateral hemisphere.
- Previous studies were limited by fixed fixation, preventing differentiation between retinotopic and spatiotopic coordinate systems.
Purpose of the Study:
- To investigate whether viewed actions are represented in retina-based (retinotopic) or more complex (spatiotopic) coordinates.
- To differentiate between coordinate systems used for representing visual action information.
Main Methods:
- Functional magnetic resonance imaging (fMRI) with participants changing gaze between conditions.
- Multivoxel pattern analysis (MVPA) to compare activation patterns.
- Regions of interest included the intraparietal sulcus (IPS) and occipitotemporal cortex.
Main Results:
- Activation patterns for conditions sharing retinotopic coordinates showed higher correlation than those with different retinotopic coordinates.
- No significant difference in correlation was found for conditions sharing spatiotopic coordinates versus non-spatiotopic ones.
- Robust activation observed in the intraparietal sulcus (IPS) and occipitotemporal cortex.
Conclusions:
- Viewed object-oriented actions are primarily maintained in retinotopic-framed coordinates.
- The brain's representation of visual actions is based on retinal position rather than a fixed spatial frame.
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