Approach and withdrawal analysis of the effects of hypothalamic stimulation and lesions in rats

Identified "purely" rewarding lateral hypothalamic and "purely" aversive medial hypothalamic electrodes in a paradigm in which Charles River male rats both initiated and terminated hypothalamic stimulation. Ss were then given a series of tests designed to assess the effects of brain stimulation on approach and withdrawal behaviors. Lateral hypothalamic stimulation facilitated approach behaviors and suppressed withdrawal behaviors, whereas medial hypothalamic stimulation produced largely the opposite effects. No serious motor deficits due to stimulation were detected with either type of electrode. In a 2nd experiment, the approach-withdrawal effects of bilateral lateral hypothalamic lesions were tested and found to suppress approach behaviors and facilitate withdrawal behaviors. Other neurological examinations revealed motor deficits, but these did not account for the specific pattern of results observed on the approach-withdrawal test. These approach-withdrawal phenomena are interpreted in terms of altering a natural balance between approach and withdrawal behavior facilitating systems in the lateral and medial hypothalamus, respectively. (43 ref) (PsycINFO Database Record (c) 2006 APA, all rights reserved).