Gradient of surface potential on a homogeneous sphere: lateral hemispheric mean magnitude

The lateral hemispheric mean of the magnitude of the gradient of scalp surface potential due to an eccentric current dipole source was determined for various source positions and orientations within a homogeneous conductive sphere. It was found that a source positioned in one hemisphere can produce a mean gradient which is larger on the surface of the opposite hemisphere. This result suggests that caution must be employed when using surface electrode measurements to establish source laterality