Passive finger movement evoked fields in magnetoencephalography.

We studied neuromagnetic fields during passive finger movements in 11 normal subjects. Activation started 27 ms after the onset of movement and remained for about 100 ms. Four activation maxima occurred within this time range, PM1 at 27 ms, PM2 at 46 ms, PM3 at 85 ms, and PM4 at 125 ms. Not all components were distinguishable in every subject partly due to overlapping effects, but PM3 was present in all subjects. Magnetic source imaging (MSI) revealed dipolar sources within 1 cm of the central sulcus for all four components. The results suggest that studying the integrity of the sensorimotor system in patients regardless of their degree of motor impairment is feasible.