Patent US 6,014,582

An instrument and method for measuring, analyzing and visualizing electrical activities in a biological system, comprising a plurality of sensors for detecting signals over a part of a surface of the biological system, a data acquisition unit for collecting the signals and for time-domain pre-processing, a positioning device for determining positions of the sensors, an estimator for determining surface differentials of the collected signals, a spatial pre-filter for reducing measurement noise in the collected signals, a spatial threshold filter for reducing volume conduction distortion, and a unit for displaying the processed signals in one of the time domain and space domain, together with the collected signals and the surface differentials of the collected signals. The collected biosignals over the scalp are also deconvolved to estimate the electrical activity over the brain surface.