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Previous Article | Next Article
The Journal of Neuroscience, November 1, 1999, 19(21):9635-9641
Amygdala Neurons Mediate Acquisition But Not Maintenance of Instrumental Avoidance Behavior in Rabbits
Amy Poremba1 and Michael Gabriel2 1 Laboratory of Neuropsychology, National Institute of Mental Health, Bethesda, Maryland 20892, and 2 Department of Psychology and the Beckman Institute, University of Illinois, Urbana, Illinois 61801
Whereas the amygdala is generally understood to be involved in aversively motivated learning, the specific associative function of the amygdala remains controversial. This study addressed the amygdalar role in mediation of discriminative instrumental avoidance learning of rabbits. Bilateral microinjection of the GABA receptor agonist muscimol centered in the basolateral nucleus of the amygdala was given to inactivate amygdalar neurons at each of three stages of acquisition. The absence of behavioral learning in rabbits trained immediately after amygdalar inactivation confirmed previous results with electrolytic lesions. The absence of savings during training after muscimol had become ineffective indicated an amygdalar role in the establishment of acquisition-relevant neural plasticity, not simply in the expression of the learned response. A time-limited role of the amygdala in instrumental avoidance learning was indicated by the finding that intra-amygdalar muscimol failed to disrupt performance of the well-established avoidance response. The passage of time alone (with no training trials) was sufficient to reduce amygdalar involvement in response performance. These results and demonstrations that other limbic system areas make time-limited contributions to learning indicate that the amygdala is part of a larger intermediate memory system that supports learning and performance before habit consolidation.
Key words: muscimol; GABAA agonist; temporary lesion; fiber-sparing lesion; rabbits; instrumental learning; avoidance learning; discriminative conditioning; retention
Copyright © 1999 Society for Neuroscience 0270-6474/99/19219635-07$05.00/0
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