SIMPLE AND CHOICE REACTION-TIME PERFORMANCE FOLLOWING OCCLUSION OF THE ANTERIOR CEREBRAL-ARTERIES IN THE RAT

Focal cerebral ischemia in the rat has traditionally been studied by e xamining the consequences of middle-cerebral artery occlusion. However , the anterior-cerebral arteries of the rat may now also be bilaterall y occluded by stereotaxic injection of the vasoconstrictor endothelin- l, resulting in ischemic damage to medial prefrontal cortex and the an teromedial basal forebrain. The behavioural consequences of anterior-c erebral artery occlusion (ACAo) were studied in two experiments using simple and choice reaction-time tasks designed to dissociate response impairments from dysfunction of motivation and attention, respectively . Following ACAo, reaction-time increased post-surgery in the choice, but not simple reaction-time task. There was also an increase in incor rect choices in the choice reaction-time task. However, the impairment s were independent of motivational or attentional function, which rema ined intact. Although the ACAo-induced ischemic damage did not disrupt motivation or attention, the results suggest that the lesion results in an executive impairment in selecting and initiating responses.