Brain Research 871 (2000) 113–119
www.elsevier.com/locate/bres
Research report
Lateral parabrachial lesions impair intraperitoneal but not
intraventricular methylscopolamine-induced taste aversion learning
a, b
*
I. Cubero , A. Puerto
a
´´´´
Departamento de Psicologıa Experimental y Psicobiologıa
,
Universidad de Almerıa
, 04120
Almerıa
,
Spain
b
´´
Departamento de Psicologıa Experimental y Fisiologıa del Comportamiento
,
Universidad de Granada
,
Granada
,
Spain
Accepted 2 May 2000
Abstract
The role of the lateral parabrachial area (lPB) in the acquisition of a delayed taste aversion learning task (TAL) was examined by
delivering the peripherally acting aversive compound, methylscopolamine (MSP), through two different routes, intraperitoneal and
intraventricular. Consistent with previous anatomical, behavioral and molecular work, electrolytic lesions centered at the lPB did impair
TAL when the MSP was injected intraperitoneally. However, lPB-lesioned animals exhibited intact learning capacities when MSP was
administered intraventricularly. These results are interpreted in terms of the lPB as a critical anatomical relay involved in bottom-up
visceral processing of aversive stimuli and also in relation to the relevance of forebrain structures in TAL. 2000 Elsevier Science B.V.
All rights reserved.
Theme
:
Neural basis of behavior
Topic
:
Learning and memory: system and functions
Keywords
:
Lateral parabrachial nucleus; Taste aversion learning; Forebrain regulation; Methylscopolamine; Visceral processing
1. Introduction parabrachial complex [19,49,51,56], receives visceral in-
puts [19,29] and has been involved in sensory processing
Taste aversion learning (TAL) is a robust associative as well as cue integration in TAL [9,10,60]. Lesions
learning for which organisms are biologically prepared, centered in the lPB disrupt an i.p. lithium- [2,9,10,41,42],
consisting of the rejection of gustatory (or flavored) stimuli morphine-induced taste aversion [6] and the TAL elicited
as a consequence of its previous pairing to visceral by electrical stimulation of the AP [1]. Similarly, recent
discomfort and malaise [11,16,25,28]. Several studies have c-Fos-like immunoreactivity data has involved this pontine
demonstrated the involvement of brainstem structures, region in visceral processing showing a related immuno-
such as the area postrema (AP) [3,7,17,22,24,32,35, reactivity pattern at lPB in i.p. lithium-, [41,53,54,58,59],
37,39,40,57], the vagus nerve [3–5] or the parabrachial ethanol- [54] or amphetamine-injected animals [41,52,55].
complex (PBN) [1,2,9,10,30,31,42] in TAL. However, the Although several results have proposed a pivotal role for
functional role of these nuclei could be related to gustatory this brainstem area in sensorial processing and/or
processing, visceral processing, and/or the integration of stimulus-association, work with decerebrated animals indi-
both cues to develop an association and consequently, to cates that the lPB might be necessary but not sufficient to
elicit gustatory-learned responses [16,43,50,60,61]. The develop and/or express TAL, which provides a clear
lateral parabrachial area (lPB), one main subdivision of the evidence for a forebrain regulation through e.g. amygdala
[8,20,21,23,44,47] and/or insular cortex, among others
[8,9,18,33,45,46].
Abbreviations: TAL, taste aversion learning; lPB, lateral parabrachial
On the basis of this background, the present paper is
region; MSP, methylscopolamine; AP, area postrema; NTS, nucleus of the
focused at evaluating the role of the lPB area in relation to
solitary tract; i.c.v., intracerebroventricular; i.p., intraperitoneal
its potential associative capacities or as a critical sensory
*Corresponding author.
E-mail address
:
icubero@filabres.ualm.es (I. Cubero)
visceral relay. The main assumption underlying this ex-
0006-8993/00/$ – see front matter 2000 Elsevier Science B.V. All rights reserved.
PII: S0006-8993(00)02453-7