Abstract
This study sought evidence for a specific cerebellar contribution to cognition by characterising the cognitive phenotype of Spinocerebellar Ataxia Type 6 (SCA-6); an autosomal dominant genetic disease which causes a highly specific late-onset cerebellar degeneration. A comprehensive neuropsychological assessment was administered to 27 patients with genetically confirmed SCA-6. General intellectual ability, memory and executive function were examined using internationally standardised tests (Wechsler Adult Intelligence Scale-III, Wechsler Memory Scale-III, Delis and Kaplan Executive Function System, Brixton Spatial Anticipation test). The patient group showed no evidence of intellectual or memory decline. However, tests of executive function involving skills of cognitive flexibility, inhibition of response and verbal reasoning and abstraction demonstrated significant impairment at the group level with large effect sizes. The results demonstrate an executive deficit due to SCA-6 that can be conceptualised as parallel to the motor difficulties suffered by these patients: the data support a role for the cerebellum in the regulation and coordination of cognitive, as well as motor processes that is relevant to individual performance.
Highlights
The cerebellum is traditionally viewed as a servomechanism for motor control that assists in the event of departure from a planned course
The cerebellum develops to a size comparable to healthy controls in Spinocerebellar Ataxia Type 6 (SCA-6) [44]; in addition the significant inverse correlations for cognitive subtests requiring both a motor and non-motor response with severity of motor impairment and disease duration suggest the deficits we show here are due to the deterioration of the cerebellum in these patients
Crossed cerebrocerebellar diaschisis cannot be ruled out as an underlying cause for the cognitive deficits in SCA-6 that we have shown in this study, as unilateral damage to the cerebellum has been shown to be accompanied by reduced blood flow in the contralateral basal ganglia and the frontoparietal cortex [6]
Summary
The cerebellum is traditionally viewed as a servomechanism for motor control that assists in the event of departure from a planned course. Anatomical studies document the connections between the cerebellum and the prefrontal and parietal areas via the ventral dentate nucleus [15,37,43], that are separate from the projections to primary motor and pre-motor areas via the dorsal dentate nucleus These projections suggest distinct anatomical bases for the contribution of the cerebellum to cognitive and motor processes. The underlying computational process within the cerebellum might be similar in both cases: a parallel can be drawn between motor correction and smoothing by the cerebellum to produce a continuous and coordinated movement, and the effect of the cerebellum on cognition [43] This parallel is most compelling in the case of executive function, where the central executive can be
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
