Responses of some neurons of the cochlear nucleus to tone-intensity increments.

The study concerns units of the cochlear nucleus of anesthetized Mongolian gerbils. The incremental stimuli consisted of short tone bursts at the units' CF (characteristic frequency) superimposed on 250‐msec pedestals of the same sound frequency and phase. The response firing rates were determined from PST (poststimulus time) histograms. In response to the pedestals, the maximum firing rate occurred at the tone onset and decayed subsequently to a steady state. The response to intensity increments was studied as a function of time delay from the pedestal onset to the increment onset. The incremental firing rate either remained constant or increased with the time delay, which means that the ratio between the incremental and pedestal firing rates always increased. The effect may be related to the psychophysical finding that intensity increments are the most difficult to detect when they occur at the pedestal onset.