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Taste Aversion Learning and Aging: A Comparison
with the Effect of Dorsal Hippocampal Lesions in Rats
I. MORON1, M. A. BALLESTEROS1,
A. CANDIDO1, M. GALLO 1,2
1Department of Experimental Psychology and Physiology
of Behavior, University of Granada, Granada, 2Institute
of Neurosciences Dr. F. Oloriz, University of Granada, Spain
Summary
The relationship between hippocampal function and aging was
explored in Wistar rats using taste aversion learning by
comparing the performance of adult dorsal hippocampal lesioned
and fifteen-month-old intact rats with that of adult intact
rats. In experiment 1 the conditioned blocking phenomenon was
absent in the hippocampal and the aging rats. Unlike the adult
intact rats, the hippocampal and aging rats were not impaired in
acquiring a learned aversion to a cider vinegar solution (3 %)
presented as a serial compound with a previously conditioned
saccharin solution (0.1 %). In experiment 2 both the hippocampal
and the aging rats developed reduced aversions to a saline
solution (0.5 %) followed by an i.p. injection of lithium
chloride (0.15 M; 2 % b.w.) if the taste solution was previously
preexposed without consequences. This latent inhibition effect
was similar to that seen in intact adult rats. In both
experiments, the aging rats exhibited enhanced conventional
learned taste aversions. It is concluded that aging is not a
unitary process but induces both hippocampal dependent and
hippocampal independent complex changes in the functioning of
the neural circuits, implementing taste aversion learning.
Key
words
Aging • Conditioned blocking • Hippocampal • Latent inhibition •
Taste aversion learning • Rat
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M. Gallo, Department of Experimental Psychology and Physiology
of Behavior, University of Granada, Campus Cartuja, Granada,
E-18071 Spain. Phone:34-58-243771 fax: 34-58-246239 e-mail:
mgallo@platonugres
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