A baseline detection method for analyzing transient electrophysiological events

Abstract

A baseline detection method has been developed that identifies and defines event transitions for whole-cell voltage or current ('transient') events that are produced by the activity of ion channel ensembles. The method utilizes a variety of iterative techniques that independently determine, for each event, several output parameters that are ultimately referrable to the mean and variance of each pre-event baseline. Examination of miniature endplate potentials using the baseline detection method provided the following output parameters for each transient event: pre-event mean and variance; rise time; peak amplitude and duration; a determination of whether the decay phase was best fit by a one- or two-component negative exponential function; time constants for the slow and/or fast decay components; percent contribution of the slow component to the decay phase; and the predicted peak amplitude determined by extrapolation of the least squares fit to the decay phase. Joint probability density representations involving the rise time and peak amplitudes of miniature endplate potentials indicated the power of this multivariate approach in identifying and isolating specific event classes. The baseline detection method is particularly advantageous for analyzing records containing multiple classes of event amplitudes, and provides a reproducible statistical standard for the analyses of transient events that are characteristic of whole-cell electrophysiological recordings.