Initial discharge latency and threshold considerations for some neurons in cochlear nuclear complex of the cat.

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Abstract
Latency behavior of neurons in the cochlear nuclear complex was studied in 45 barbiturate-anesthetized cats. Stimuli were tonal bursts usually 50-500 ms in duration. Latency of the initial discharge is a systematic function of the frequency and intensity of the tone for a large class of neurons which are termed latency precedence cells. Most cells in the anteroventral cochlear nucleus and many neurons in the anterior division of the posteroventral nucleus belong to this class. Unless otherwise stated, all findings pertain to this cell group. There is usually a correspondence between the discharge rate of a given neuron and the latency of the initial discharge, the higher the discharge rate the shorter the latency. An unexpected finding was that the initial discharge at threshold is a low probability event that can be evoked, except for a short initial time period, by any stimulus cycle throughout the tone duration. As stimulus intensity is increased a central latency value becomes apparent and the mean latency shortens rapidly. Some population measurements were made. No systematic relation was found between the latency of the initial discharge and threshold of the neuron when the tonal stimulus was set at a specific number of decibels above threshold. There is a systematic relation between mean latency and best frequency. This relation was utilized to derive an estimate of the travel time of the mechanical disturbance along the cochlear partition. There are cells in every major division of the cochlear nuclear complex whose latency behavior differs in various ways from that of the latency precedence neurons. A few such cell types were described.