Monkey Posterior Parietal Cortex Neurons Antidromically Activated from Superior Colliculus. Martin Paro and ROBERT H. WURTZ. Laboratory of Sensorimotor Research, National Eye Institute, National Institutes of Health, Bethesda, Maryland 20892.
APStracts 4:259N, 1997.
ABSTRACT
The connection between the posterior parietal cortex (PPC) and the superior colliculus (SC) was investigated by antidromically activating neurons within the lateral intraparietal (LIP) area with single-pulse stimulation delivered to the intermediate layers of the SC. To dissociate visual and saccade-related responses, the discharge properties of the identified efferent neurons were studied in the delayed visually guided saccade task and the memory guided saccade task. We found that the great majority (74%) of the identified LIP efferent neurons have a peripheral visual receptive field, typically with a broad spatial tuning. About two-thirds (64%) exhibited sustained activity during the delay period of the behavioral tasks, during which the monkeys had to withhold eye movements, and 80% of these increased their activity just before the onset of saccades. Both delay and pre-saccadic discharges in the delayed visually guided saccade task were higher than in the memory guided saccade task. These results establish that the neuronal signal sent by LIP to the SC carries both visual and saccade-related information. 

Received 12 August 1997; accepted in final form 16 September 1997.
APS Manuscript Number J663-7.
Article publication pending J. Neurophysiol.
ISSN 1080-4757 Copyright 1997 The American Physiological Society.
Published in APStracts on 7 October 1997