Experimental verification of Marr-Albus' plasticity assumption for the cerebellum

Marr-Albus model of the cerebellum is based on the assumption that parallel fiber-Purkinje cell synapses are plastically modifiable under influences of conjunctive activation of a climbing fiber and a mossy fiber on the same Purkinje cell. This article introduces a positive support for this assumption derived from the recent experiment by Ito. Sakurai and Tongroach on rabbit flocculus. Possible reasons why the experimental verification of Marr-Albus' assumption has been so difficult are considered, and applicability of Marr-Albus model of the cerebellum to problems of motor learning is discussed.