[Tridimensional cartography of potentials recorded on the human scalp: I. Interpolation with tridimensional functions].

Human cerebral electrophysiological studies make an increasing use of mapping to represent potentials recorded on the scalp. In order to draw potential maps a projection on a plane of the recording electrodes is required. An interpolation of the values of points between electrodes must then be performed. We have compared three interpolation methods (surface splines, spherical splines and tridimensional interpolation functions). The last two methods are interesting because, avoiding one projection, they do not create map distortions. Statistical evaluation of the three methods, using a dipolar model, shows the overall superiority of the tridimensional interpolation.