Cerebello-cortical plasticity. Role of somesthetic influx in the change of the cerebellar effects on the musculature.
In awake chronically preparated cats with a neurotoxic lesion of the red nucleus, persistent thalamo-cortical and intracortical synaptic plasticity reinforcing the pre-established cerebello-thalamocortical (CTC) influences on the forelimb musculature was observed under associative alpha-conditioning. This plasticity occurs when the activation of the CTC circuits (conditioned stimulus, CS) producing a given motor response, was associated with somesthetic stimulation (unconditioned stimulus, UCS), producing the same movement. These CTC circuits are in fact liable to undergo modifications in two opposite ways depending on the motor responses induced by the UCS. A reinforcement of their action on the forearm flexor muscles was observed when the UCS produces elbow flexion reflex, whereas a depression of this action in favour of a potentiated cerebellar action on the forearm extensor muscles occurred when the UCS produces a shoulder retraction reaction. The mechanisms possibly underlying these changes, and their implications in motor learning processes are discussed in light of previous data.
Meftah
E M
EM
Centre de recherche Cerveau et Cognition, Faculté de médecine de Toulouse-Rangueil, CNRS UMR 9940, Toulouse, France.
Rispal-Padel
L
L
D000818:Animals; D002415:Cats; D002525:Cerebellar Cortex / Q000502:physiology*; D003214:Conditioning, Classical / Q000502:physiology; D004558:Electric Stimulation; D007858:Learning / Q000502:physiology; D009046:Motor Neurons / Q000502:physiology; D009132:Muscles / Q000502:physiology*; D009473:Neuronal Plasticity; D013788:Thalamus / Q000502:physiology