The human cerebellum contributes to motor, emotional and cognitive associative learning. A review.

In this review results of human lesion studies are compared examining associative learning in the motor, emotional and cognitive domain. Motor and emotional learning were assessed using classical eyeblink and fear conditioning. Cerebellar patients were significantly impaired in acquisition of conditioned eyeblink and fear-related autonomic and skeletal responses. An additional finding was disordered timing of conditioned eyeblink responses. Cognitive learning was examined using stimulus-stimulus-response paradigms, with an experimental set-up closely related to classical conditioning paradigms. Cerebellar patients were impaired in the association of two visual stimuli, which could not be related to motor performance deficits. Human lesion and functional brain imaging studies in healthy subjects are in accordance with a functional compartmentalization of the cerebellum for different forms of associative learning. The medial zone appears to contribute to fear conditioning and the intermediate zone to eyeblink conditioning. The posterolateral hemispheres (that is lateral cerebellum) appear to be of additional importance in fear conditioning in humans. Future studies need to examine the reasonable assumption that the posterolateral cerebellum contributes also to higher cognitive forms of associative learning. Human cerebellar lesion studies provide evidence that the cerebellum is involved in motor, emotional and cognitive associative learning. Because of its simple and homogeneous micro-circuitry a common computation may underly cerebellar involvement in these different forms of associative learning. The overall task of the cerebellum may be the ability to provide correct predictions about the relationship between sensory stimuli.