GUSTATORY AND MULTIMODAL NEURONAL RESPONSES IN THE AMYGDALA DURING LICKING
AND DISCRIMINATION OF SENSORY STIMULI IN AWAKE RATS.
HISAO NISHIJO, TERUKO UWANO, RYOI TAMURA, AND TAKETOSHI ONO.
Department of Physiology, Faculty of Medicine, Toyama Medical and
Pharmaceutical University, Sugitani 2630, Toyama 930-01, Japan.
APStracts 4:0255N, 1997.
ABSTRACT
The amygdala (AM) receives information from various sensory modalities via the
neocortex and directly from the thalamus and brainstem, and plays an important
role in ingestive behaviors. In the present study, neuronal activity was
recorded in the AM and amygdalostriatal transition area of rats during
discrimination of conditioned sensory stimuli and ingestion of sapid
solutions. Of the 420 responsive neurons, 227 responded exclusively to one
sensory modality, 120 responded to two or more modalities, and the remaining
73 could not be classified. Among the responsive neurons, 108 responded to
oral-sensory stimulation (oral-sensory neurons). In detailed analyses of 84 of
these oral-sensory neurons, 24 were classified as taste responsive, and were
located mainly in the central nucleus of the AM. The other 60 oral-sensory
neurons were classified as non-taste oral-sensory neurons, and were
distributed widely throughout the AM. Both the taste and non-taste oral-
sensory neurons also responded to other sensory stimuli. Of the 24 taste
neurons, 21 were tested at least with 4 standard taste solutions. Based on the
magnitudes of their responses to these sapid stimuli, the taste neurons were
classified as follows: 7 sucrose-best, 4 NaCl-best, 3 citric acid-best, and 6
quinine HCl-best. The remaining cell responded significantly only to lysine
HCl and monosodium glutamate. Multivariate analyses of these 21 taste neurons
suggested that, in the AM, taste quality was processed based on palatability.
Taken with previous lesion studies, the present results suggest that the AM
plays a role in the evaluation of taste palatability and in the association of
taste stimuli with other sensory stimuli.
Received 27 February 1997; accepted in final form 12 September 1997.
APS Manuscript Number J169-7.
Article publication pending J. Neurophysiol.
ISSN 1080-4757 Copyright 1997 The American Physiological Society.
Published in APStracts on 7 October 1997