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Dissociable systems for visually guided navigation versus reaching and grasping in human parietal cortex.
Hee Kyung Yoon1, Yaelan Jung1, Daniel D Dilks1
1Department of Psychology, Emory University, 36 Eagle Row, Atlanta, GA, 30322, United States.
Cerebral Cortex (New York, N.Y. : 1991)
|May 1, 2026
Summary
The parietal cortex has two distinct regions: the superior parietal lobule (SPL) for navigation and the superior parietal occipital cortex (SPOC) for reaching and grasping. This clarifies how the brain organizes visually guided actions.
Area of Science:
- Neuroscience
- Cognitive Neuroscience
- Neuroimaging
Background:
- The parietal cortex is crucial for visually guided actions.
- Distinct regions for navigation, reaching, and grasping remain unclear.
- Previous research suggests the superior parietal lobule (SPL) for navigation and superior parietal occipital cortex (SPOC) for reaching/grasping.
Purpose of the Study:
- To investigate whether the parietal cortex contains specialized regions for different visually guided actions.
- To determine if SPL and SPOC functions are dissociable.
Main Methods:
- Functional magnetic resonance imaging (fMRI) in adult participants.
- Presentation of four visual stimulus types: Dynamic Scenes, Static Scenes, Contextual Reaching and Grasping, and Isolated Reaching and Grasping.
- Resting-state functional connectivity analysis.
Main Results:
- A double dissociation was observed: SPL showed greater activation for Dynamic Scenes (navigation) than Static Scenes and reaching/grasping conditions.
- SPOC showed greater activation for reaching and grasping conditions than scene conditions.
- Functional connectivity revealed SPL linked to leg-motor cortex and SPOC to arm-motor cortex.
Conclusions:
- The findings reveal two distinct parietal systems: SPL for visually guided navigation and SPOC for visually guided reaching and grasping.
- This clarifies the functional organization of the parietal cortex in visually guided action.
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