A behavioural and anatomical investigation of amygdaloid mediation of affective memory

This thesis examined the involvement of the lateral, central and basolateral nuclei of the amygdala in both appetitive and aversive affective behavior. In Experiment I, using electrolytic lesions, it was found that damage to the lateral but not central or basolateral nuclei blocked a Conditioned Cue Preference (CCP) to food (Froot Loops) in rats that were not deprived of food. In Experiment II, also using electrolytic lesions, it was found that damage to the basolateral but not central or lateral nuclei blocked a Conditioned Cue Aversion (CCA) produced by a lithium chloride injection (42 mg/kg). In Experiment III results similar to those in Experiments I and II were obtained using axon-sparing NMDA lesions. The results of Experiments I-III demonstrate a double dissociation of affective memory with respect to the amygdala. The lateral nucleus of the amygdala mediated the memory of an appetitive affective experience and the basolateral nucleus mediated memory for an aversive affective experience.In Experiment IV the contributions of appetitive and aversive affective states to a food CCP were examined. Lesions of the lateral but not the basolateral nucleus were found to attenuate but not completely eliminate a food CCP when the rats were food deprived in the Paired compartment and sated in the Unpaired compartment. Food deprivation alone produced a CCA and lesions of the basolateral but not the lateral nucleus blocked this effect. The possibility that both the appetitive and aversive behaviours are mediated through connections from the dopamine-reward centres in the ventral striatum is discussed