Coding of information in single auditory-nerve fibers of the goldfish

Abstract

Patterns of activity in single fibers of the saccular branch of the auditory nerve of goldfish [Carassius auratus] were analyzed in response to acoustic stimulation. Neurons were categorized on the basis of differences in spontaneous activity patterns, rates of adaption and frequency response areas. The sensitivity and responsiveness of neurons were presented in terms of impulse rate and synchronization (phase locking). Nonspontaneous neurons fell into 2 clear frequency response area categoreis based upon impulse rate criteria. Spontaneously active neurons had continuously distributed frequency response characteristics based upon synchronization criteria. Functions relating impulse rate responsiveness to frequency indicated that frequency was coded only crudely as an across-fiber pattern of impulse rates. Synchronization responsiveness functions showed that frequency was coded temporally with the same precision in the goldfish auditory nerve as in mammals, at 1000 Hz and below.