Glutamatergic activity in the amygdala signals visceral input during taste memory formation.
Proceedings of the National Academy of Sciences. 2002-08-07; 99(17): 11417-11422
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1. Proc Natl Acad Sci U S A. 2002 Aug 20;99(17):11417-22. Epub 2002 Aug 7.
Glutamatergic activity in the amygdala signals visceral input during taste memory
Miranda MI(1), Ferreira G, Ramirez-Lugo L, Bermudez-Rattoni F.
(1)Departamento de Neurociencias, Instituto de Fisiologia Celular, Universidad
Nacional Autónoma de México, 04510 México D.F., México.
Conditioned taste aversion (CTA) is a learning paradigm in which an animal avoids
a taste (conditioned stimulus) previously associated with visceral toxic effects
[or unconditioned stimulus (US)]. Although many studies have implicated
glutamate-mediated neurotransmission in memory consolidation of different types
of learning tasks, including CTA, the exact role of this neurotransmitter system
in memory formation is not known. Thus, we set out to determine whether glutamate
mediates signaling of the US in CTA. We present evidence obtained by in vivo
microdialysis that the US (i.p. injection of lithium chloride) induced a dramatic
increase in glutamate release in the amygdala and a modest but significant
release in the insular cortex. Moreover, CTA can be elicited by intra-amygdalar
microinjections of glutamate; consequently, when glutamate is administered just
before the presentation of a weak US, a clear CTA is induced. In contrast, the
injection of glutamate alone or glutamate 2 h after the suboptimal US did not
have any effect on the acquisition of CTA. These results indicate that glutamate
activation of the amygdala can partially substitute the US in CTA, thus providing
a clear indication that the amygdala conveys visceral information for this kind
PMID: 12167678 [Indexed for MEDLINE]