A BASE-LINE DETECTION METHOD FOR ANALYZING TRANSIENT ELECTROPHYSIOLOGICAL EVENTS

A baseline detection method has been developed that identifies and def ines event transitions for whole-cell voltage or current ('transient') events that are produced by the activity of ion channel ensembles, Th e method utilizes a variety of iterative techniques that independently determine, for each event, several output parameters that are ultimat ely referrable to the mean and variance of each pre-event baseline. Ex amination of miniature endplate potentials using the baseline detectio n method provided the following output parameters for each transient e vent, pre-event mean and variance; rise time; peak amplitude and durat ion: a determination of whether the decay phase was best fit by a one- or two-component negative exponential function; time constants for th e slow and/or fast decay components: percent contribution of the slow component to the decay phase; and the predicted peak amplitude determi ned by extrapolation of the least squares fit to the decay phase. Join t probability density representations involving the rise time and peak amplitudes of miniature endplate potentials indicated the power of th is multivariate approach in identifying and isolating specific event c lasses. The baseline detection method is particularly advantageous for analyzing records containing multiple classes of event amplitudes, an d provides a reproducible statistical standard for the analyses of tra nsient events that are characteristic of whole-cell electrophysiologic al recordings.