Topographic mapping of single-sweep evoked potentials as a picture of the spatio-temporal dynamics in the brain

The results from two methods combined to gain insight into the dynamic behavior obtained in response to a given stimulus are reported. Single-sweep optimal processing of evoked potentials is used to process the recorded signal from 16 electrodes on the skull in order to obtain single responses. The spatial interpolation of the filtered signals over the modeled cranial surface gives a pictorial color-coded mapping of the potential distribution estimated at every signal sample, without the need for synchronized averaging. A topographic mapping referred to the traditional average, to a single filtered evoked potential, and to the original recorded data, at the 178-ms latency corresponding to the P200 peak for median nerve somatosensory stimulation, is shown and discussed. The results shows that the method is effective for noninvasive monitoring during physiological or psychological tasks characterized by fast dynamics. It employs easy-to-use devices and simple clinical procedures