NORMATIVE DATA FOR CALLOSALLY AND CORTICO SPINALLY MEDIATED ELECTROMYOGRAPHIC EFFECTS IN HAND MUSCLES FOLLOWING A HEMISPHERE-SELECTIVE MAGNETIC CORTEX STIMULATION IN MAN

Normative data are presented for a standardized transcranial magnetic motor cortex stimulation (focal eightshaped coil, antero-posterior coi l currents, 80% of maximal stimulator output, maximal tonic contractio n of hand muscles) for different callosally and corticospinally mediat ed electromyographic effects in the first dorsal interosseus muscle. T he data shall serve as a basis for a more widespread use of magnetic c ortex stimulation to investigate the function of callosal motor fibres . Parameters of callosally mediated inhibitory effects are the onset l atency and duration of transcallosal inhibition and the transcallosal latency time. No significant side differences were found for any of th e different parameters, Parameters of corticospinally mediated effects which originate from the same motor cortical area are response thresh old, onset latency, central and peripheral latency and the amplitude o f excitatory electromyographic responses in contralateral muscles, The duration of postexcitatory inhibition in contralateral muscles is als o given as an inhibitory carticospinally mediated effect.