Sm. Brasser et Ne. Spear, A SENSORY-ENHANCED CONTEXT FACILITATES LEARNING AND MULTIPLE MEASURESOF UNCONDITIONED STIMULUS-PROCESSING IN THE PREWEANLING RAT, Behavioral neuroscience, 112(1), 1998, pp. 126-140
This study tested the hypothesis that increased processing or efficacy
of the unconditioned stimulus (US) contributes to the facilitation of
trace conditioning that occurs when preweanling rats are conditioned
in a novel sensory-rich context. Experiment 1 extended previous findin
gs (D. L. McKinzie & N. E. Spear, 1995) of facilitated acoustic trace
conditioning in the 17-day-old rat in a sensory-enhanced versus a home
odor context. In the enhanced or more familiar context, Experiment 2
tested rats of this age for degree of spontaneous locomotor activity a
nd ultrasonic vocalizations, activity and ultrasounding in response to
shock, and the acoustic startle reflex. The enhanced context resulted
in a greater overall activity response to shock, increased ultrasound
ing to discrete shocks, and a sensitized latency to startle. The resul
ts suggest that enhanced US processing in a sensory-rich context is a
likely contributor to its facilitative effect on infant learning.