Are spacial extension and recruitment of motor cortical inhibition related? Evidence using transcranial magnetic stimulation

In studies using transcranial magnetic stimulation (TMS) it has been hypothesized (Ridding and Rothwell, 1997) that stimulus-response curves of motor evoked potentials (MEP) constructed by gradually increasing the stimulus intensity (SI) but leaving the site of excitation unchanged might contain similar information than MEP-maps where the coil is moved but the SI remains unchanged. Here, we wanted to test this hypothesis for cortically evoked silent periods (CSP) thought to reflect inhibitory cortical circuits. The stimulus-response curves for SPs (CSP-RC)in small hand muscles of 15 healthy volunteers (mean age…