Short-term and long-term habituation of the acoustic startle response in chronic decerebrate rats.

13 chronic decerebrate male albino rats, maintained in good condition for 31–84 postoperative days, showed significant within-session habituation of the acoustic startle response. However, they showed no habituation over days under conditions that produced significant response deficits in controls. The decerebrates' stimulus-provoked response deficits may have endured for up to 40 min between sessions, and they were apparently more than normally susceptible to stimulus-provoked sensitization. Data are consistent with models that assume that the mechanisms for short-term habituation are intrinsic to the stimulus-response (S–R) pathway in the lower brain stem. On the other hand, relatively permanent long-term habituation of the acoustic startle response must be mediated by extrinsic mechanisms rostral to the S–R pathway that superimpose an inhibitory influence on that pathway. (32 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)