Intracranial Evidence for the Cerebellum's Role in Semantic Processing

Language impairments in patients with cerebellar damage or dysfunction strongly implicate the cerebellum in language processing but the nature, timing, and specificity of its contributions are unclear. A clinical trial of cerebellar stimulation for motor recovery after middle cerebral artery stroke provided a rare opportunity to record invasive, intracranial local field potential activity from the cerebellar dentate nucleus of eight patients during language processing. Patients performed semantic priming tasks that either discouraged or encouraged semantic predictions. We found evidence for communication between the dentate nucleus and frontal scalp EEG sites in the alpha band when semantic predictions were violated. This did not occur when semantic predictions were fulfilled or when prediction violations were nonlinguistic in nature. This language-specific activity occurred in the N400window where semantic processing of a visually presented word takes place. These data point to a linguistic feedback function that could help to account for the language deficits observed in diseases and disorders involving the cerebellum.