Time-frequency distribution of neuronal activity in the gerbil inferior colliculus responding to auditory stimuli

We classified the firing pattern of neurons in the central nucleus of the inferior colliculus (ICc) in a time-frequency coordinate, except for simple phasic onset responses, into four groups using tone bursts with a wide frequency range. The ICc is the major nucleus in the auditory midbrain. Single-unit recordings were made from ICc contralateral to the monaurally stimulated ear in anesthetized gerbils. Neurons of three out of the four groups (53.8%) demonstrated that the firing distribution changed depending on time and frequency, which was not shown previously. Neurons of one group (37.6%) exhibited a frequency response range that changed little with time. The remaining neurons (8.6%) belonged to none of the above classifications. The time-frequency-sensitive neurons in ICc may be good candidates for coding communication sounds, which comprise complex temporal changes in frequency.