[Response of cochlear nucleus neurons of the cat to complex tone]

The response of the cochlear nucleus neurons in the anesthetized cat to complex tones has been studied for understanding the processing of tonal informations in that nucleus. Forty-eight cats were used in this study and data was obtained from 148 neurons with microelectrode technique. Two kinds of stimulus tones were applied and each of them consisted of pure tones (f1, f2, f3) and three complex tones (f1 + f2, f1 + f3, f2 + f3). The first group was composed of three pure tones of 670, 1250, 2400Hz and the second group was composed of those of 350, 500, 1100Hz, respectively. In 50 out of 148 cochlear nucleus neurons, we obtained some responses to complex tones. Response patterns to complex tones in 34 out of 50 cochlear nucleus neurons were similar to response patterns which had been obtained from auditory nerve. In 16 out of 50 neurons, however, the PST histogram pattern which had been obtained by complex tone stimuli did not show the same pattern as that of pure tone stimuli. For example, in same neuron, sustained type and pauser type responses had obtained by pure tones stimulus, but chopper type response had obtain by complex tone stimuli. And some neural activities were facilitated by the complex tones. From these results it can be speculated that the certain functions of the processing of the complex tones will be exist in the cochlear nucleus.