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Shape selectivity in primate lateral intraparietal cortex
1Division of Neuroscience, Baylor College of Medicine, Houston, Texas 77030, USA. sereno@cmbn.rutgers.edu
Nature
|October 17, 1998
Summary
Neurons in the posterior parietal cortex, part of the "where" visual pathway, demonstrate shape selectivity. This suggests the "where" pathway also processes object features, independent of movement.
Area of Science:
- Neuroscience
- Visual Perception
- Cognitive Neuroscience
Background:
- The extrastriate visual cortex is functionally divided into temporal ('what') and parietal ('where') regions.
- Neuropsychological studies support this functional segregation.
- The role of prefrontal cortex in integrating 'what' and 'where' information is under investigation.
Purpose of the Study:
- To investigate shape selectivity in the posterior parietal cortex ('where' pathway).
- To determine if the 'where' pathway contributes to processing object features independently of motor actions.
Main Methods:
- Recorded neuronal activity in the posterior parietal cortex of primates during a fixation task.
- Utilized a delayed match-to-sample paradigm to assess neuronal responses to shape stimuli.
- Analyzed neuronal unit activity for shape selectivity and delay-period differences related to sample shape.
Main Results:
- Many neurons in the posterior parietal cortex exhibited sensory shape selectivity for 2D geometric shapes.
- Neuronal units showed significant differences in delay-period activity contingent on the sample shape.
- Shape selectivity in the posterior parietal cortex was comparable to that observed in the ventral ('what') pathway.
Conclusions:
- Neurons in the posterior parietal cortex ('where' pathway) contribute to attending to and remembering shape features.
- This shape processing occurs independently of eye movements, reaching, or object manipulation.
- Findings challenge strict functional segregation by demonstrating feature processing within the spatial 'where' pathway.
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