Motor cortex inhibition in patients with ataxia.
We studied the effects of a subthreshold magnetic stimulus over the motor cortex and an electrical stimulus over the cerebellum on EMG responses produced by a suprathreshold magnetic stimulus over the motor cortex. In normal subjects, both subthreshold conditioning stimuli and cerebellar stimuli could suppress responses to suprathreshold magnetic test stimuli when given at appropriate timings: "cortico-cortical" and "cerebellar" inhibition, respectively. In all patients with degenerative ataxias and patients with a lesion in the cerebellar thalamus, the "cortico-cortical" inhibition was normal and the "cerebellar" inhibition was absent. We conclude that cerebellar systems make no or little contribution to the above-mentioned "cortico-cortical" inhibition.
Ugawa
Y
Y
Department of Neurology, School of Medicine, University of Tokyo, Japan.
Hanajima
R
R
Kanazawa
I
I
D000328:Adult; D000704:Analysis of Variance; D001259:Ataxia / Q000503:physiopathology*; D004576:Electromyography; D006801:Humans; D008280:Magnetics; D008875:Middle Aged; D009044:Motor Cortex / Q000503:physiopathology*; D009433:Neural Inhibition; D013997:Time Factors