Point process model of LSO unit discharges

Abstract

A point process model for the responses of single auditory‐nerve fibers to time‐varying stimuli was extended to describe lateral superior olive (LSO) unit responses to monaural cf tones. In contrast to auditory‐nerve fiber discharges, successive interspike‐intervals of LSO unit discharges exhibit serial dependence. This dependence was found to be well described by a first‐order Markov model of the underlying point process. The characteristics of this model were measured from the conditional interval histogram: the usual interspike interval histogram restricted to those intervals preceded by an interval of a specified duration. From this quantity, the conditional hazard function was derived. This computation revealed that the influence of the pentultimate interval was to shift the hazard function. This detailed description of the serial dependence cannot be derived from measurements of serial correlation coefficients. The cf tone burst responses of LSO units are characterized as “chopper”‐type. Within the context of the point process model outlined above, the parameters of the model were measured from the sustained portion of the tone burst response. Using the model thus derived, the initial chopping portion of the response was predicted. [Work supported by NINCDS and NSF.]