CEREBRAL POTENTIALS DURING SMOOTH GOAL-DIRECTED HAND MOVEMENTS IN RIGHT-HANDED AND LEFT-HANDED SUBJECTS

During smooth goal-directed hand movements a negative potential shift can be recorded from the human scalp. This goal-directed movement potential (GDMP) is preponderant over central areas with a maximum at the vertex and, over the motor cortex, contralaterally larger than ipsilterally to the moving hand. In 11 right-handed and 6 left-handed subjects, the morphology and distribution of these potential shifts were studied in relation to task differences, moving hand and handedness. The results show a functional differentiation of two components of the GDMP: (1), a lateralized, slow negative wave, restricted to the precentral area and selectively varying with the hand used, and (2), a widespread, bilateral symmetrical component, selectively influenced by taskspecific and individual factors. Two effects reflect an influence of the subjects's handedness on the GDMP: (a) averaged for both hand conditions, there are larger amplitudes over the hemisphere contralateral to the dominant hand, and (b) averaged for both hemispheres, larger amplitudes result from using the nondominant hand. © 1979 Springer-Verlag.