The role of motivation and the amygdala in the association of stimuli.

Note:The effect of hunger on sensory preconditioning was explored. An appetitive task was used to test for sensory preconditioning effects in order to avoid complications arising from differences of drive state during preconditioning and testing for preconditioning. It was found that hunger facilitated the association between paired auditory and visual stimuli, but not between stimuli presented separately and in random order. It was also found that bilateral lateral amygdaloid lesions disrupted the facilitating effect of hunger on sensory preconditioning, but not on preconditioning per se. Examination of the orientation responses of animals during preconditioning, indicated that the auditory stimulus becomes an arousing cue that signals the onset of the visual stimulus. It is suggested that the orientation responses produced as a consequence of this cue function are responsible for the association of the auditory and visual stimuil. Furthermore, differences in the orientation response patterns of the lesioned and normal animals suggest that the lesion disrupts these orientation-attentional responses. Such a disruption may account for the lack of hunger facilitation of sensory preconditioning in lesioned animals. These results implicate the amygdala in orientation-attentional processes