Functional localization of the sensory hand area with respect to the motorcentral gyrus knob

THE aim of this work was to investigate the topography of the primary senso ry hand cortex with magnetoencephalography in order to define the functiona l anatomy of this area in healthy humans. Previous studies denoted an inver ted Omega or an horizontal epsilon shaped knob on the pre-central gyrus as a landmark for the motor hand area; therefore a systematic difference betwe en the orientation of the source for thumb with respect to little finger sh ould be observed. We found this systematic difference, but the direction of the sources activated during thumb and little finger stimulation did not c onverge, as would be expected if only the Omega convexity is activated: in fact our results suggest that thumb sensory area also extends to the area l ateral to this convexity. (C) 1999 Lippincott Williams & Wilkins.