Article révisé par les pairs
Résumé : The hereditary ataxias are a group of genetically defined neurological diseases, which are characterized by a heterogeneous clinical presentation. Their overall prevalence is estimated to be 3-9/100,000. The autosomal dominant cerebellar ataxias (spinocerebellar ataxias - SCA), the recessive ataxias and the other forms of inherited ataxias often present with a core of cerebellar deficits (the so-called cerebellar syndrome) combining oculomotor disorders, dysarthria, dysmetria/kinetic tremor, and/or ataxic gait, although other signs of neurological involvement may predominate. During the last 20 years, there has been increasing debate about the possible non-motor roles of the cerebellar circuitry. In particular, cerebellar modules would be involved in fronto-executive functions, visuo-constructive skills, behaviour and affect/emotion. Numerous studies carried out in spontaneous or engineering mutant mice reinforce the idea that cerebellar damage affects both cognition and emotions-related behaviours. Clinical descriptions of hereditary ataxias report such cognitive deficits to variable extents, confirmed by neuropsychological studies. Deficits mainly fall in the following domains: executive control, attention, memory and learning, visuo-spatial abilities and language. The confrontation with imaging investigations and neuropathological studies, the comparison of the symptoms found in the various inherited ataxias as well as data obtained in animals suggest that these deficits result from disruption of cerebro-cerebellar connections. Data support the hypothesis that the cerebellar circuitry tunes and integrates the information in these networks in order to provide the necessary pre-processing and to increase the automaticity with the aim of reaching elaborate abstraction.