Cerebellar involvement in cognitive flexibility.

The aim of the present study was to investigate whether the cerebellar structures are involved in functions requiring cognitive flexibility abilities. The flexibility of the hemicerebellectomized and control animals in learning a four-choice learning task, adapting to ever-changing response rules was investigated. While in the initial phase of the task both experimental groups exhibited similar performances, only the control animals significantly improved their performance as the sessions went by. The lack of improvement in lesioned animals' performance rendered their responses particularly defective in the final phases of the task, when conversely intact animals performed best, exploiting their "learning to learn" ability. The findings demonstrate the defective influence of the cerebellar lesion on the acquisition, not the execution, of new responses. The results underline the crucial role of the cerebellum in mediating cognitive flexibility behaviors.