New method for titrating differences in scalp topographic patterns in brain evoked potential mapping.

A method is described for computing a Z estimator for the quantitative comparison of topographical patterns in 2 maps. Z can assume values between 1 and -1. The procedure is illustrated on a 3-shell head model for different configurations of current dipoles in the head space. The sensitivity of Z estimation can be adjusted by different weighting procedures or by using an average reference. When Z = 1 indicates identity of the set of active dipoles in the 2 maps compared, a dilation factor can be computed to estimate the enhanced or reduced activity of these generators.