Defective cerebellar control of cortical plasticity in writer's cramp.

A large body of evidence points to a role of basal ganglia dysfunction in the pathophysiology of dystonia, but recent studies indicate that cerebellar dysfunction may also be involved. The cerebellum influences sensorimotor adaptation by modulating sensorimotor plasticity of the primary motor cortex. Motor cortex sensorimotor plasticity is maladaptive in patients with writer's cramp.

Cerebellar sensory processing alterations impact motor cortical plasticity in Parkinson's disease: clues from dyskinetic patients.

The plasticity of primary motor cortex (M1) in patients with Parkinson's disease (PD) and levodopa-induced dyskinesias (LIDs) is severely impaired. We recently reported in young healthy subjects that inhibitory cerebellar stimulation enhanced the sensorimotor plasticity of M1 that was induced by paired associative stimulation (PAS). This study demonstrates that the deficient sensorimotor M1 plasticity in 16 patients with LIDs could be reinstated by a single session of real inhibitory cerebellar stimulation but not sham stimulation.

Acute dopamine boost has a negative effect on plasticity of the primary motor cortex in advanced Parkinson's disease.

Plasticity of primary motor cortex is severely impaired in Parkinson's disease and chronic dopaminergic treatment is reported not to rescue it. The effect of an acute dose of levodopa on cortical plasticity reported so far is variable. In this study, it was hypothesized that cortical plasticity would be restored in Parkinson's disease as a long duration response to treatment in stable responders while those with motor complications would have a reduction or loss of plasticity similar to the decay of long duration response of motor signs.