Single-neuron modeling of LSO unit responses.

We investigated, using a computational model, the biophysical correlates of measured discharge patterns of lateral superior olive (LSO) neuron responses to monaural and binaural stimuli. The model's geometry was based on morphological data, and static electric properties of the model agree with available intracellular responses to hyperpolarizing current pulses. Inhibitory synapses were located on the soma and excitatory ones on the dendrites, which were modeled as passive cables.

Input from the medial nucleus of trapezoid body to an interaural level detector.

The medial nucleus of the trapezoid body (MNTB) contains components of a neural network that functions as an interaural level difference (ILD) detector. In the cat, lateral superior olivary (LSO) neurons compare the contralateral inhibitory input from the MNTB with an excitatory input form the ipsilateral anteroventral cochlear nucleus to extract information about binaural stimuli. To better specify the inhibitory inputs to the LSO and gain a better understanding of the inhibitory component of the LSO network, the response characteristics of MNTB neurons were examined in cats under stimulus conditions similar to those used to study LSO inhibitory responses.

Transient effects during the chopping response of LSO neurons.

The initial transient chopping response of LSO neuron discharges to both monaural and binaural tone-burst stimuli in the context of a previously developed point process model of the later sustained response is analyzed and modeled. The analysis reveals the nature of the initial transient response to stimulus onset: The model's stimulus-dependent parameters vary with poststimulus-onset time while the neuron's intrinsic recovery characteristics remain constant throughout the response. By applying maximum-likelihood estimation techniques to determine the time course of the stimulus-dependent parameters, it was found that the initial excitatory and inhibitory effects decay exponentially, with their ratio determining the instantaneous rate of firing and their relative latency determining the extent of the initial chopping pattern.

The brain stem evoked response and medial nucleus of the trapezoid body.

Single-unit responses of cat superior olivary complex neurons to acoustic stimuli were examined to determine whether the units' action potentials were sufficiently synchronized to contribute to the brain stem evoked response. The medial nucleus of the trapezoid body and lateral superior olive are two major nuclei within the cat superior olivary complex. The first-spike discharge latencies of medial nucleus of the trapezoid body and lateral superior olivary neurons to monaural presentations of tone burst stimuli were measured as a function of stimulus level.

A nonstationary Poisson point process describes the sequence of action potentials over long time scales in lateral-superior-olive auditory neurons.

The behavior of lateral-superior-olive (LSO) auditory neurons over large time scales was investigated. Of particular interest was the determination as to whether LSO neurons exhibit the same type of fractal behavior as that observed in primary VIII-nerve auditory neurons. It has been suggested that this fractal behavior, apparent on long time scales, may play a role in optimally coding natural sounds.