The role of the cerebellum in affect and psychosis

Anatomical, clinical, find functional imaging studies suggest that the cerebellum is an essential component of the distributed neural circuitry subserving cognition. This paper addresses the experimental and clinical data pointing to the role of the cerebellum in the modulation of affect and emotion as well as of thought. There are cerebellar connections with the reticular system (arousal), hypothalamus (autonomic function and emotional expression), limbic system (experience and expression of emotion), and paralimbic and neocortical association areas (cognitive dimensions of affect). Clinical studies point to cerebellar modulation of aggression and mood, including the cerebellar cognitive affective syndrome in adults and children, the posterior fossa syndrome of transient mutism and behavioral change following surgery that involves the vermis, and behavioral modification by cerebellar neurosurgical manipulation. Functional imaging studies reveal cerebellar involvement in nociception, in autonomic behaviors such as hunger and thirst, and in affective experiences. These observations provide support for the hypothesis that the cerebellum is an essential node in the distributed neural circuitry subserving cognitive and affective functions, and that there is a topographic organization of behaviors in the cerebellum The hypothesis that the phylogenetically older fastigial nucleus, vermis and flocculonodular robe constitute the "limbic cerebellum" is further developed to suggest that these cerebellar structures should be considered an extension of the Papez circuit. The concept is proposed that there is a universal cerebellar transform (UCT), possibly error detection, prevention, and correction utilizing an internal model, the disruption of which leads to dysmetria, the universal cerebellar impairment (UCI). Dysmetria of movement, or ataxia, is matched by dysmetria of thought, including the cerebellar cognitive affective syndrome, abnormalities of affect, and psychotic thinking. (C) 2000 published by Elsevier Science Ltd. All rights reserved.