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Reaching in the dark: enhanced responses in posterior parietal cortex
W A MacKay1, A J Mendonça, B Blum
1Department of Physiology, University of Toronto, Canada.
Neuroreport
|October 1, 1990
Summary
Visual input is less crucial for area 7 neuronal activity during reaching tasks. Some neurons enhance activity in darkness, suggesting somatic responsiveness compensates for lost visual guidance.
Area of Science:
- Neuroscience
- Primate motor control
- Sensory processing
Background:
- Area 7 plays a role in visually guided reaching.
- The contribution of visual versus somatosensory input to area 7 is not fully understood.
Purpose of the Study:
- To determine the importance of visual feedback for area 7 neuronal activity during reaching.
- To investigate how area 7 neurons respond when visual guidance is removed.
Main Methods:
- A monkey was trained to reach for visual targets on a monitor.
- Neuronal activity in area 7 was recorded with and without visual feedback (reaching in darkness).
- Reach-related cells were identified and their discharge patterns analyzed.
Main Results:
- Ten out of 19 reach-related cells in area 7 showed enhanced discharge in darkness.
- This enhancement was observed in both area 7a (active during reach) and area 7b (screen contact sensitive) cells.
- The findings suggest a shift in responsiveness when visual cues are absent.
Conclusions:
- Visual input is not solely responsible for guiding reaches processed by area 7.
- Somatosensory information may play a compensatory role when visual feedback is lost.
- Area 7 exhibits adaptable neuronal activity patterns based on sensory availability during motor tasks.