Early cerebellar activation predicts response time

Despite increasing evidence to the contrary, there remains a widespread perception that cerebellum performs an exclusively motor-related role. In order to investigate its cognitive role, activation in the cerebellum during the first 200 ms of a mental rotation task was analyzed. 306-channel magnetoencephalographic data were collected from 12 participants during the performance of mental rotation (Rotation) and control (Control) tasks. Participants were asked to judge whether the paired images represented the same object viewed from different angles (Match) or different objects (Mismatch), and to indicate their response with their dominant hand using a response pad. L1 minimum norm estimates were calculated for trials with correct responses. Reaction times (RTs) were extracted in MATLAB. RTs for the Rotation and Control conditions were regressed stepwise on cerebellar onset latency, peak latency, and peak amplitude. For the Rotation RTs, peak amplitude in the left cerebellum approached significance as a predictor of Match RTs, while both peak amplitude and peak latency in the right cerebellum were significant predictors of Mismatch RTs. These results indicate that cerebellum is engaged immediately in sensory and cognitive processing of the visual images that determine correct choice reaction response selection.