Browsing by Author "Roze, E"
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Item Abnormal cerebellar processing of the neck proprioceptive information drives dysfunctions in cervical dystonia.(Sci Rep. 2018, 2018-02) Popa, T; Hubsch, C; James, P; Richard, A; Russo, M; Pradeep, S; Krishan, S; Roze, E; Meunier, S; Kishore, AThe cerebellum can influence the responsiveness of the primary motor cortex (M1) to undergo spike timing-dependent plastic changes through a complex mechanism involving multiple relays in the cerebello-thalamo-cortical pathway. Previous TMS studies showed that cerebellar cortex excitation can block the increase in M1 excitability induced by a paired-associative stimulation (PAS), while cerebellar cortex inhibition would enhance it. Since cerebellum is known to be affected in many types of dystonia, this bidirectional modulation was assessed in 22 patients with cervical dystonia and 23 healthy controls. Exactly opposite effects were found in patients: cerebellar inhibition suppressed the effects of PAS, while cerebellar excitation enhanced them. Another experiment comparing healthy subjects maintaining the head straight with subjects maintaining the head turned as the patients found that turning the head is enough to invert the cerebellar modulation of M1 plasticity. A third control experiment in healthy subjects showed that proprioceptive perturbation of the sterno-cleido-mastoid muscle had the same effects as turning the head. We discuss these finding in the light of the recent model of a mesencephalic head integrator. We also suggest that abnormal cerebellar processing of the neck proprioceptive information drives dysfunctions of the integrator in cervical dystonia.Item Cerebellar Processing of Sensory Inputs Primes Motor Cortex Plasticity(CEREBRAL CORTEX, 2013) Popa, T; Velayudhan, B; Hubsch, C; Pradeep, S; Roze, E; Vidailhet, M; Meunier, S; Kishore, APlasticity of the human primary motor cortex (M1) has a critical role in motor control and learning. The cerebellum facilitates these functions using sensory feedback. We investigated whether cerebellar processing of sensory afferent information influences the plasticity of the primary motor cortex (M1). Theta-burst stimulation protocols (TBS), both excitatory and inhibitory, were used to modulate the excitability of the posterior cerebellar cortex and to condition an ongoing M1 plasticity. M1 plasticity was subsequently induced in 2 different ways: by paired associative stimulation (PAS) involving sensory processing and TBS that exclusively involves intracortical circuits of M1. Cerebellar excitation attenuated the PAS-induced M1 plasticity, whereas cerebellar inhibition enhanced and prolonged it. Furthermore, cerebellar inhibition abolished the topography-specific response of PAS-induced M1 plasticity, with the effects spreading to adjacent motor maps. Conversely, cerebellar excitation had no effect on the TBS-induced M1 plasticity. This demonstrates the key role of the cerebellum in priming M1 plasticity, and we propose that it is likely to occur at the thalamic or olivo-dentate nuclear level by influencing the sensory processing. We suggest that such a cerebellar priming of M1 plasticity could shape the impending motor command by favoring or inhibiting the recruitment of several muscle representations.Item Defective cerebellar control of cortical plasticity in writer's cramp(Brain., 2013-07) Hubsch, C; Roze, E; Popa, T; Russo, M; Balachandran, A; Pradeep, S; Mueller, F; Brochard, V; Quartarone, A; Degos, B; Vidailhet, M; Kishore, A; Meunier, SItem Reply: A single session of cerebellar theta burst stimulation does not alter writing performance in writer's cramp(BRAIN, 2015) Meunier, S; Popa, T; Hubsch, C; Roze, E; Kishore, A