Symbolic representations of action in the human cerebellum.

Cerebellar cortical areas connected to the neocortical motor system process information important for the sensory guidance of action. Converging evidence also supports the view that cerebellar cortical areas connected with the prefrontal cortex process information similarly in the cognitive domain. Here, we test the hypothesis that the prefrontal-projecting zones in the human cerebellum process the abstract content of information embedded within sensory cues. Specifically, we use event-related fMRI to determine whether symbolic visual instructions activate the prefrontal-projecting zones of the cerebellum. On the basis of connectional anatomy, we predicted that such activity would be found in lobule HVIIA and adjacent vermal territories in the same lobule. Our experimental design enabled us to investigate activity time-locked specifically to instructions foraction that were either purely symbolic, or specified actions directly. Such activity was independent of action. Activity specifically time-locked to symbolic cues (compared with non-symbolic control cues) activated cerebellar cortical lobule HVIIA (Crus I and Crus II). Our results provide support for the view that prefrontal-projecting areas of the cerebellar cortex process information that is of a purely abstract nature.