The effect of amygdalectomy on orienting and classical conditioning in monkeys.

The basic findings of these two studies are as follows: a failure of orientating and conditioning of viscero-autonomic responses, but essentially normal orienting and conditioning of a temporal muscle response in amygdalectomized animals. Small procedural differences exist between the two studies,and a possible order effect exists as a result of the use of the same subjects consecutively. However, we fell that the difference between the responses of the viscero-autonomic system and the skeletal system would still be found were all of the measures gathered simultaneously in an optimal conditioning situation. The definitive study--simultaneous viscero-autonomic and skeletal (behavioral) recording--remains to be done. Trial-by-trial analysis of the correlations or lack of correlations between these responses in such a study should be highly informative. These two studies offer substantial information relevant to the original questions. When behavior is modified by simple repetition of experience the effect of amygdalectomy is restricted to the viscero-autonomic components of orienting and classical conditioning, not to the entire spectrum of responses. The issue raised, therefore, is the significance of the viscero-autonomic components of orienting and classical conditioning. The suggestion has been proposed (Pribram, 1969) that these components serve as mechanisms of internal rehearsal necessary to the registration (as novel or familiar) of the orienting and conditioning experience. This proposal requires further testing.