The Journal of Neuroscience, February 1, 2002, 22(3):1171-1176
Competition between Memory Systems: Acetylcholine Release in the
Hippocampus Correlates Negatively with Good Performance on an
Amygdala-Dependent Task
Christa K.
McIntyre1,
Shanthi N.
Pal2,
Lisa K.
Marriott3, and
Paul E.
Gold4
1 Department of Neurobiology and Behavior, University
of California, Irvine, California 92697, 2 Department of
Pharmacology, Hamdard University, New Delhi, India 110062, 3 Arizona Research Laboratories, Division of Neural
Systems, Memory and Aging, University of Arizona, Tucson, Arizona
85724, and 4 Department of Psychology, University of
Illinois at Champaign-Urbana, Champaign, Illinois 61820
Lesions of the amygdala impair acquisition of a food conditioned
place preference (CPP) task. In contrast, lesions of the fornix
facilitate acquisition on this task, showing that an intact hippocampal
system can interfere with learning an amygdala-dependent task. Our
recent findings indicate that acetylcholine (ACh) release in the
hippocampus increases while rats perform a hippocampus-dependent spontaneous alternation task. To the extent that ACh output in the
hippocampus reflects activation of that brain area in learning and
memory, the results obtained with fornix lesions suggest that ACh
release in the hippocampus might be negatively correlated with learning
on a CPP task. Using in vivo microdialysis, release of
ACh was measured in the hippocampus while rats learned and were tested
on an amygdala-dependent CPP task and a hippocampus-dependent spontaneous alternation task. Release of ACh in the hippocampus increased when rats were tested on either task. The magnitude of the
increase in release of hippocampal ACh was negatively correlated with
good performance on the amygdala-dependent CPP task. These findings
suggest that ACh release may reflect activation and participation of
the hippocampus in learning and memory, but in a manner that can be
detrimental to performance on a task dependent on another brain area.
Key words:
competition; memory systems; amygdala; hippocampus; microdialysis; conditioned place preference; acetylcholine
Copyright © 2002 Society for Neuroscience 0270-6474/02/2231171-06$05.00/0
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