CONDITIONED PLEASURE ATTENUATES THE STARTLE RESPONSE IN RATS

The acoustic startle response of rats was found to be attenuated if el icited in the presence of a conditioned stimulus predicting reward. Du ring conditioning, animals received a total of 21 pairings of light wi th palatable food and sucrose solution, whereas controls received food and sucrose in the absence of light. The amplitude of the acoustic st artle response was significantly reduced in the presence of light in c onditioned animals, but not in controls. It is assumed that a conditio ned response to light is the activation of a central state of pleasure . We therefore suggest that ''pleasure-attenuated startle'' reflects a mechanism by which a defensive or aversive response is attenuated dur ing a pleasant, hedonic state. (C) 1995 Academic Press, Inc.