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How humans reach: distinct cortical systems for central and peripheral vision
Simon Clavagnier1, Jérôme Prado, Henry Kennedy
1Laboratorium voor Neuroen Psychofysiologie, Medical School, K.U. Leuven, Belgium.
Summary
Visually guided hand movements rely on two distinct brain systems. One system controls reaching in central vision, while another manages reaching in peripheral vision, impacting optic ataxia.
Area of Science:
- Neuroscience
- Cognitive Neuroscience
- Neuroimaging
Background:
- Optic ataxia results from posterior parietal cortex lesions, disrupting visually guided hand movements.
- Deficits primarily in peripheral vision suggest separate neural substrates for foveal and extrafoveal reaching.
Purpose of the Study:
- To investigate the distinct neural networks involved in reaching to central versus peripheral visual targets.
- To determine if different brain systems support reaching in foveal and extrafoveal vision.
Main Methods:
- Functional magnetic resonance imaging (fMRI) was used in healthy subjects.
- Brain activity was analyzed during reaching tasks in central and peripheral vision conditions.
Main Results:
- Reaching in central vision activated a network including the medial intraparietal sulcus (mIPS) and dorsal premotor cortex (PMd).
- Reaching in peripheral vision engaged a broader network, notably the parieto-occipital junction (POJ).
- The POJ area aligns with lesion sites previously linked to optic ataxia.
Conclusions:
- Two distinct cortical systems control reaching, differentiated by the visual field of the target.
- One system, involving mIPS and PMd, is for central vision reaching.
- A separate system, including the POJ, is implicated in peripheral vision reaching and optic ataxia.
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