Réorganisations cérébrales fonctionnelles dans la dysarthrie parkinsonienne

摘要

The three main cerebral dysfunctions associated with upper limb movements in Parkinson's disease (PD) are 1/ an underactivation of the supplementary motor area (SMA) and the dorsolateral prefrontal cortex (DLPFC), 2 /an overactivation of the primary motor cortex (M1) corresponding to the upper limb somatotopy and 3/ an overactivation of the cerebellum. The dysfunction of the motor circuit implying the basal ganglia (BG) seems to be compensated by the increased activation of the cortex-cerebellum-cortex loop. Regards to speech production in PD, the changes displayed are 1/an overactivation of the rostral part of the SMA and the DLPFC, 2 /an underactivation of the M1 cortex corresponding to the orofacial somatotopy and 3/ an underactivation of the cerebellum. These results reinforce the fact that the two parallel motor circuitries, involving the BG and the cerebellum respectively, are implicated in speech motor control. In PD, the dysfunction of the first circuit seems to deteriorate the activation of the second. An experimental task combining the two types of movements (of the upper limb and speech production) revealed an absence of motor area activations (M1 cortex, cerebellum) associated with speech production: the profile of hand movements was only observed; it seems that in PD, a loss of functional additivity regards to cerebral activations should be expected.