AUTOMATIC ENHANCEMENT OF CLINICAL EVOKED POTENTIALS

A VARIETY OF PROBES OF BRAIN FUNCTION HAVE BEEN DEVELOPED BYCLINICIANS AND NEUROSCIENTISTS BASED ON MEASUREMENT OF SCALP-RECORDED ELECTRICAL POTENTIALS EVOKED BY SPECIFIC STIMULI, SO-CALLED EVOKED POTENTIALS (EPS). SIGNAL ENHANCEMENT OF EPS IS TYPICALLY ACCOMPLISHED BY ENSEMBLE AVERAGING. IN THIS PHASE I STUDY, AUTOMATIC METHODS FOR GREATLY ENHANCING EPS ARE INVESTIGATED, INCLUDING THE EXTRACTION OF MEANINGFUL INFORMATION FROM VERY FEW AND EVEN SINGLE EPS (SEPS). AN INITIAL STUDY DEMONSTRATED CONSIDERABLE ENHANCEMENT OF TRANSIENT PHENOMENA, WHICH HAVE BEEN INACCESSIBLE TO AVERAGING TECHNIQUES, AS WELL AS GREAT REDUCTION IN THE TIME REQUIRED TO ADMINISTER ESTABLISHED EP MEASUREMENTS. FOR EACH STIMULUS PRESENTATION, A PARAMETRIC MODEL IS ESTIMATED FROM PRESTIMULUS DATA, AND POSTSTIMULUS DATA ARE FILTERED USING THE MODEL. THE MODELING METHOD IS ARECENTLY DEVELOPED CANONICAL VARIATE ANALYSIS (CVA) OF MULTIVARIATE TIME SERIES. IN THE PRESENT STUDY, A VARIETY OF STIMULUS PARADIGMS ARE USED, AND THE PHYSIOLOGICAL VALIDITY OF THE ENHANCED EPS IS EVALUATED. THE ENHANCEMENT TECHNIQUE IS EVALUATED ON DATA ACQUIRED FOR CLINICAL ASSESSMENT AND FOR INTRAOPERATIVE MONITORING, INCLUDING THE SIGNAL-TO-NOISE ENHANCEMENT AND THE REQUIRED COMPUTATION. IN PHASE II, THE SIGNAL ENHANCEMENT COMPUTATIONS WILL BE OPTIMIZED FOR REAL-TIME IMPLEMENTATION ON A MICROCOMPUTER, AND GENERAL PURPOSE INPUT/OUTPUT ROUTINES WILL BE DEVELOPED TO PROVIDE THE BROADEST POSSIBLE APPLICABILITY OF THE METHOD.