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Dynamic circuitry for updating spatial representations. I. Behavioral evidence for interhemispheric transfer in the
Rebecca A Berman1, Laura M Heiser, Richard C Saunders
1Department of Neuroscience and Center for the Neural Basis of Cognition, University of Pittsburgh, Pittsburgh, PA 15213, USA.
Journal of Neurophysiology
|May 13, 2005
Summary
Direct cortical links are crucial for updating visual spatial representations during eye movements. However, split-brain monkeys showed surprising recovery, indicating a flexible cortico-subcortical network supports this process.
Area of Science:
- Neuroscience
- Cognitive Science
- Visual System Research
Background:
- Maintaining accurate spatial representations during self-motion, like eye movements, is vital for sensory processing.
- The visual system uses spatial updating to keep track of important locations as the eyes move.
- The specific neural pathways responsible for spatial updating remain largely uncharacterized.
Purpose of the Study:
- To investigate the necessity of direct cortico-cortical connections for spatial updating.
- To determine if forebrain commissures are essential for updating visual representations across different visual hemifields.
Main Methods:
- Assessed spatial updating in two split-brain monkeys using a double-step saccade task.
- Analyzed performance on sequential target presentations requiring updates across visual hemifields.
Main Results:
- Split-brain monkeys initially showed deficits in updating visual representations across hemifields.
- These deficits were not permanent, with monkeys regaining the ability to perform across-hemifield updates, sometimes rapidly.
- Impairments were selective to sequences requiring interhemispheric visual updating.
Conclusions:
- Direct cortical pathways are the primary substrate for visual spatial updating.
- The visual system exhibits remarkable plasticity, with cortico-subcortical networks compensating for the loss of direct cortical links.
- A redundant network supports a stable visual space representation through reorganization.