TEMPERATURE EFFECTS ON AUDITORY-NERVE FIBER RESPONSE IN THE AMERICAN BULLFROG

Single fiber recordings were made from auditory nerve fibers of the American bullfrog (Rana catesbeiana). As temperature was raised: 1. (1) Best frequencies of fibers from the amphibian papilla (N = 15) increased. Below 600 Hz best frequency changes up to 0.06 oct/°C were found; above 600 Hz changes were less than 0.03 oct/°C. In the basilar papilla (N = 4) no significant increase of best frequency was found. 2. (2) Spike rates in response to fixed-RMS-amplitude stimuli increased considerably; Q10 of spike rate ranged from 5 to 10. 3. (3) Spontaneous activity, found in basilar papilla fibers, increased with average Q10 = 1.6 (±0.3). 4. (4) A conspicious change of tuning quality factor Q10dB was only observed in two fibers, that were taken to low temperatures (<16°C). 5. (5) the nearly linear frequency vs. phase relation in amphibian papilla shifts to higher frequency (along with shift of best frequency), while its average slope remains nearly unchanged. © 1990.