During pain-avoidance neurons activated in the macaque anterior cingulate and caudate

Lesions in either the anterior cingulate cortex (ACC) or the caudate nucleu s (CN) impair avoidance behavior from noxious somatic stimuli, so these two areas may play a similar role in pain-avoidance behavior. To test this hyp othesis, we recorded single neuronal activities in the ACC and in the CN of a monkey while it was performing a pain-avoidance task. Ten of 136 ACC and eleven of 160 CN neurons responded selectively during pain-avoidance behav ior. We found little difference in the population distribution or in the re sponse latency and duration. Our present findings are in accordance with pr evious lesion and anatomical studies which suggest that these two regions c ould function as one module in pain-avoidance behavior. (C) 2000 Published by Elsevier Science Ireland Ltd. All rights reserved.