| The role of the cerebellar cortex in eyeblink classical conditioning remains unclear. Experimental manipulations that disrupt its normal function impair learning to various degrees, and task parameters may be important factors in determining the severity of impairment. In this thesis, the role of cerebellar cortex is examined with task parameters that are either optimal or non-optimal for rabbits to learn the conditioned eyeblink response (CR). Specifically, the cerebellar cortico-nuclear connection was pharmacologically disrupted with localized drug infusions to the rabbit cerebellum during eyeblink conditioning with an interstimulus interval (ISI)-switch procedure. One group of rabbits was first trained with a 250-ms ISI (optimal) and then switched to a 750-ms ISI (non-optimal). A second group was trained in the opposite order. The most striking effect was that CR learning was most severely impaired, across all drug treatment groups, when the initially-trained ISI was not optimal. This suggests that a properly functioning cerebellar cortico-nuclear connection is very important for initially learning eyeblink conditioning when parameters are arranged to make it more difficult. The results fit well with a growing body of literature that stands in support of the idea that the important neural resources for learning eyeblink conditioning become more distributed as the task becomes more difficult.;Keywords. Cerebellum; Eyeblink Classical Conditioning; ISI; GABA; Glutamate... |
