Differential effects of beta-adrenergic receptor blockade in basolateral amygdala or insular cortex on incidental and associative taste learning.
Neurobiology of Learning and Memory. 2008-07-01; 90(1): 54-61
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1. Neurobiol Learn Mem. 2008 Jul;90(1):54-61. doi: 10.1016/j.nlm.2008.01.004. Epub
2008 Feb 13.
Differential effects of beta-adrenergic receptor blockade in basolateral amygdala
or insular cortex on incidental and associative taste learning.
Miranda MI(1), Rodríguez-García G, Reyes-López JV, Ferry B, Ferreira G.
(1)Departamento de Neurobiología Conductual y Cognitiva, Instituto de
Neurobiología, Universidad Nacional Autónoma de México, AP 1-1141, 76001
Querétaro, QRO, Mexico.
The importance of central beta-adrenergic system has been essentially
investigated in aversive/emotional learning tasks. However, recent data suggest
that the beta-adrenergic system is also required for incidental taste learning.
In the present study we evaluated in rats whether beta-adrenergic receptor
activity is required for taste habituation, an incidental taste learning, and
also for conditioned taste aversion (CTA) learning, an associative learning. To
address this issue, a low dose of the beta-adrenergic antagonist propranolol was
infused before learning in either the basolateral amygdala (BLA) or the insular
cortex (IC), two forebrain areas reported to play a key role in taste memory
formation. Incidental taste learning was assessed using a single presentation of
the sweet taste saccharin 0.1%, which is sufficient to increase saccharin
consumption (relative to water baseline) during a second presentation. CTA was
assessed by pairing the first saccharin 0.1% presentation with a delayed gastric
malaise, thus causing a decrease in saccharin consumption (relative to water
baseline) during a second presentation. Propranolol infusion in BLA
(1microg/0.2microl) or IC (2.5microg/0.5microl) before the first taste exposure
impaired incidental taste learning but did not affect CTA. These results
highlight the important role played by the beta-adrenergic receptor activation in
cortical and amygdaloid structures during taste learning. Moreover, they are the
first to suggest that incidental learning is more sensitive to blockade of
noradrenergic system than associative learning.
PMID: 18276171 [Indexed for MEDLINE]