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Preservation of pointing accuracy toward moving targets after extensive visual cortical ablations in cats
M Fabre-Thorpe1, F Levesque, P Buser
1Centre de Recherche Cerveau et Cognition, UMR 9940, Toulouse.
Abstract:
Impairments in reaching toward stationary and moving targets were studied in cats after restricted or extensive removal of visual cortical areas (areas 17, 18 and 19 and lateral suprasylvian visual areas). Regardless of the extent of the cortical lesion, cats were at first unable to localise and reach for a stationary target whereas they were soon able to detect and accurately point toward a mobile one. Moreover, the onset latency of such movements was dramatically increased. During post-operative re-training, the cats were unable to improve their accuracy scores when reaching towards stationary targets. In contrast, full compensation was observed for the accuracy of reaching movements directed toward moving targets. A partial recovery was observed for movement latency values that progressively decreased but left a permanent 30-40 ms impairment following extensive lesions. The role of extrageniculate messages and alternative routes involving other cortical areas in taking in charge the visuomotor activity is discussed.
Insights
Cats with visual cortex damage struggled to reach for stationary objects but could accurately reach for moving ones. Recovery varied, with full accuracy for moving targets but persistent latency issues.
Area of Science:
- Neuroscience
- Visual Cortex Function
- Visuomotor Control
Background:
- The visual cortex is crucial for visuomotor tasks.
- Understanding visual processing after cortical damage is key to brain function research.
Purpose of the Study:
- To investigate the effects of visual cortical lesions on reaching behaviors in cats.
- To assess the recovery of reaching for stationary versus moving targets.
Main Methods:
- Cats underwent restricted or extensive removal of visual cortical areas (17, 18, 19, and lateral suprasylvian).
- Reaching accuracy and movement latency towards stationary and moving targets were assessed post-surgery.
- Post-operative re-training was conducted to evaluate recovery.
Main Results:
- Lesions impaired reaching for stationary targets but allowed accurate reaching for moving targets.
- Movement onset latency increased significantly after lesions.
- Full accuracy recovery was observed for reaching towards moving targets, while stationary target reaching accuracy did not improve.
- Partial recovery of movement latency occurred, with a persistent deficit after extensive lesions.
Conclusions:
- The visual cortex plays a differential role in processing stationary versus moving targets.
- Alternative neural pathways may compensate for visual cortical damage, particularly for dynamic visuomotor tasks.
- Extrageniculate pathways and other cortical areas may contribute to visuomotor activity post-lesion.