We investigated the hypothesis that Parkinsons's disease (PD) is associated with abnormal plasticity of the neuronal circuits mediating blink reflex. We induced long-term potentiation (LTP)-like plasticity in trigeminal wide dynamic range neurons of the blink reflex circuit by pairing an high-frequency train of electrical stimuli over the right supraorbital nerve (SO) coincident with the R2 response elicited by a preceding SO stimulus. The facilitation of the R2 response after the induction protocol was markedly decreased in patients relative to controls. Treatment with dopaminergic drugs normalized the LTP-like plasticity of the R2 response. We conclude that nigrostriatal denervation disrupts LTP-like plasticity in the trigeminal reflex circuit.
Copyright 2006 Movement Disorder Society.