Transcranial Magnetic Stimulation (TMS)

TMS was performed using a Magstim 200 stimulator connected to a figure-of-eight-shaped coil with an internal wing diameter of 70 mm (Magstim Company Ltd, Whitland, UK). At the start of the experimental sessions M1 and M2 the motor “hot spot” of the abductor pollicis brevis (ABP) muscle was determined. The coil was held with the handle pointing backwards and laterally 45° to the interhemispheric line to evoke anteriorly directed current in the brain and was optimally positioned to obtain motor evoked potentials (MEP) in the APB of the dominant hand (“hot spot”). The subjects were wearing a tight fitting cotton wool cap on which the coil position was marked using a soft tip pen in order to ensure that the coil was held in a constant position during the experimental session.

Stimulation intensities are quoted as percentage of maximal stimulator output (mean ± SEM).