A. Aguero et al., THE FUNCTIONAL RELEVANCE OF MEDIAL PARABRACHIAL NUCLEUS IN INTRAGASTRIC SODIUM CHLORIDE-INDUCED SHORT-TERM (CONCURRENT) AVERSION LEARNING, Neurobiology of learning and memory, 67(2), 1997, pp. 161-166
The functional meaning of the visceral information processing in the m
edial parabrachial nucleus (PBNm) was analyzed in this study through a
short-term aversion learning task. In this short-term task the animal
s (Wistar rats) had to learn to discriminate between two different gus
tatory-olfactory stimuli presented simultaneously (two graduated buret
tes); one of the stimuli was associated with the concurrent intragastr
ic administration of an aversive chemical agent (hypertonic NaCl) and
the other stimulus was paired with no injection. In the first experime
nt, the PBNm-lesioned animals are unable to learn the task using gusta
tory stimuli (saccharin and quinine) that surpassed the detection thre
shold of parabrachial-lesioned rats. Moreover, in a second experiment,
the PBNm-lesioned animals were unable to learn the task when there wa
s no initial preference for either of the gustatory-olfactory stimuli
presented (strawberry or coconut). However, this short-term task is le
arned by lateral parabrachial nucleus (PBNl) lesioned animals. The pos
sibility that the PBNm and the PBNl are involved in distinct mechanism
s of visceral processing is discussed. (C) 1997 Academic Press.