The cerebellum is incorporated into the distributed neural circuits subserving motor control, cognitive processing and the modulation of emotion. This lecture provides an overview of anatomical studies in monkey and functional magnetic resonance imaging studies in humans demonstrating topographic arrangement in the cerebellum of motor and non-motor domains. We consider motor impairments such as ataxia, dysmetria and dysarthria as resulting from lesions of the motor cerebellum predominantly in the anterior lobe, whereas executive, linguistic, spatial, and emotional impairments (the cerebellar cognitive affective syndrome, CCAS) arise following lesions of the cognitive cerebellum in the posterior lobe. Affective dysregulation occurs particularly when lesions involve the cerebellar vermis. These higher order impairments represent subcortical disconnection syndromes, manifestations of dysmetria of thought resulting from loss of the universal cerebellar transform, the unique computation that the cerebellum contributes to functionally specific subcircuits within distributed cortico-subcortical networks. Patient studies reveal that the affective component of the CCAS manifests as deficits in the domains of attentional control, emotional control, social skill set, autism spectrum disorders and psychosis spectrum disorders. This new appreciation of cerebellar circuits, functions, and deficits has relevance for understanding and treating adults and children with cerebellar disorders; investigating neuropsychiatric diseases including autism and schizophrenia; and for new therapeutic possibilities in neuropsychiatry. This is exemplified by preliminary evidence that transcranial magnetic stimulation applied to the cerebellar vermis improves negative symptoms and enhances quality of life in patients with schizophrenia.
Objective for this lecture are:
- To define the essential elements of the distributed neural circuits linking cerebellum with association and paralimbic areas as well as sensorimotor regions of the cerebral cortex.
- Describe the clinical features and broader relevance of the cerebellar cognitive affective syndrome and the neuropsychiatry of the cerebellum.
- Explain how the dysmetria of thought theory and the concept of the universal cerebellar transform account for the cerebellar role in cognition and emotion, and the relevance this has for novel approaches to treatment of neuropsychiatric disorders.