Timing mechanisms in the cerebellum: Testing predictions of a large-scale computer simulation

We used large-scale computer simulations of eyelid conditioning to investig ate how the cerebellum generates and makes use of temporal information. In the simulations the adaptive timing displayed by conditioned responses is m ediated by two factors: (1) different sets of granule cells are active at d ifferent times during the conditioned stimulus (CS), and (2) responding is not only amplified at reinforced times but also suppressed at unreinforced times during the CS. These factors predict an unusual pattern of responding after partial removal of the cerebellar cortex that was confirmed using sm all, electrolytic lesions of cerebellar cortex. These results are consisten t with timing mechanisms in the cerebellum that are similar to Pavlov's "in hibition of delay" hypothesis.