Rf. Rogers et al., The cerebellum is necessary for rabbit classical eyeblink conditioning with a non-somatosensory (photic) unconditioned stimulus, BEH BRA RES, 104(1-2), 1999, pp. 105-112
The present research investigated the acquisition of classically conditione
d eyeblinks in rabbits using a light flash unconditioned stimulus (US), as
well as the contribution of deep cerebellar nuclei to such an association.
Two independent groups of animals experienced three phases of training: (1)
pre-lesion delay conditioning using either a light- (Group 1) or an air pu
ff-US (Group 2), (2) post-lesion testing of response performance, and (3) p
ost-lesion acquisition to the opposite US. During the initial acquisition (
720 trials), the groups did not differ with regard to their rate of learnin
g or their overall level of responding. To assess the contribution of the c
erebellum to the maintenance of responding, the interpositus nucleus was el
ectrolytically lesioned and animals were given 8 days of additional trainin
g. Both groups exhibited a profound reduction in conditioned responding (CR
) and showed no signs of recovery over the remainder of this phase (480 tri
als). Animals were then shifted to the opposite US (same eye) and given 12
days of training to assess the effect of interpositus lesions on the acquis
ition of CRs to a novel US. No learning was observed during this phase, reg
ardless of whether animals experienced the light- or air puff-US. These res
ults demonstrate: (1) the ability of a non-somatosensory stimulus to serve
as a US during classical eyeblink conditioning; and (2) a common reliance o
n deep cerebellar nuclei for both somatosensory- and non-somatosensory-base
d reflexive motor learning. The findings are discussed in reference to the
processing of conditioning stimuli within the brainstem-cerebellar circuitr
y that underlies eyeblink conditioning. (C) 1999 Elsevier Science B.V. All
rights reserved.