2006年10月24日，在安徽省六安市金寨县响洪甸水库附近的矿洞中捕捉到1只腹侧颈部白化的雌性几内亚长翼蝠（Miniop terus magnater: Chiroptera，Vespertilionidae），该只白化个体的体重、头体长、前臂长、胫骨长、后足长、尾长、耳长和耳宽分别为14.4g、50.1mm、48.2mm、20.7mm、9.3mm、51.2mm、10.7mm和8.8mm，均在正常个体数据范围之内。

We recorded extracellular activity from 402 single units located in the inferior colliculus (IC) of barbiturate-anesthetized albino mice. The stimuli were pure tones at characteristic frequency (CF) with durations of 10, 40 and 100 ms and intensities ranged from 5 to 25 dB above unit’s minimum threshold (MT). The tones were presented with different repetition rates (RRs) ranging from 0.2 to 20.0 Hz. At low intensities (5 dB above MT, determined at RR of 0.5 Hz) the great majority of units exhibited a strong decline of their responses when the stimulus RR was increased. About one-half of the units did not respond to 40 ms tones when they were stimulated with the RR of 3.0 Hz. This effect was even more pronounced for 100 ms tones. Generally, the increase in stimulus intensity led to an increase in the high-frequency border of RR. Nevertheless, even at intensities of 20-30 dB above MT, some units showed no response when the RR exceeded 5.0 Hz. In many cases the band-pass or high-pass duration tuning of the single unit was transformed to low-pass or all-pass when the rate was low enough to guarantee the independence of successive presentations of the stimuli. Responses of a very small group of IC units, however, were enhanced when the RR was increased. Our data have shown that the changes in the RR radically modify many features of the neural response (number of spikes, latency, discharge pattern, duration selectivity). We suggest that long-lasting inhibitory processes may be induced by low intensity stimuli in many units of the IC.

In acoustic communication, animals must extract biologically relevant signals that are embedded in noisy environment. The present study examines how weak noise may affect the auditory sensitivity of neurons in the central nucleus of themouse inferior colliculus (IC)which receives convergent excitatory and inhibitory inputs from both lower and higher auditory centers. Specifically, we studied the frequency sensitivity and minimum threshold of IC neurons using a pure tone probe and a weak white noise masker under forward masking paradigm. For most IC neurons, probe-elicited response was decreased by a weak white noise that was presented at a specific gap (i.e. time window). When presented within this time window, weak noise masking sharpened the frequency tuning curve and increased the minimum threshold of IC neurons. The degree of weak noise masking of these two measurements increased with noise duration. Sharpening of the frequency tuning curve and increasing of the minimum threshold of IC neurons during weak noise masking were mostly mediated through GABAergic inhibition. In addition, sharpening of frequency tuning curve by the weak noise masker was more effective at the high than at low frequency limb. These data indicate that in the real world the ambient noise may improve frequency sensitivity of IC neurons throughGABAergic inhibitionwhile inevitably decrease the frequency response range and sensitivity of IC neurons.

Echolocation calls and neurophysiological correlations with auditory response properties in the inferior colliculus of Pipistrellus abramus (Microchiroptera: Vespertilionidae). Zoological Studies 46(5): 622-630. The present study examines the echolocation calls and auditory responses of single neurons in the inferior colliculus (IC) of Pipistrellus abramus (Microchiroptera: Vespertilionidae). The data showed that there was a neurophysiological correlation of the auditory response properties with echolocation calls in IC neurons. The echolocation calls of P. abramus were broad-band swept from 86.6 to 43.2 kHz. The ending frequencies of the first harmonics which centered around 40 (average, 43.2; range, 37.0-47.0) kHz, were relatively more stable than the initial high frequencies. The average peak frequency was 52.1 (range, 43.3-57.6) kHz of which the majority (81%, 154 of 190 calls) ranged from 50.1 to 60 kHz. We recorded the responses of 75 single IC neurons to pure tones. Most IC neurons had the best frequency (BF) at between 30 and 50 kHz (centered around 40 kHz) (73%, 54 of 75) and between 50.1 and 60 kHz (19%, 14 of 75), respectively corresponding to the ending frequencies of the first harmonics and peak frequencies. The minimum threshold (MT) distribution was wider, and the average MT was significantly higher for neurons with a BF of 30-50 kHz than for neurons with a BF of 50.1-60 kHz (62±11vs. 49±8 dB SPL, p<0.001, t-test). The latency distribution was also slightly wider for neurons with a BF of 30-50 kHz (71% between 6.1 and 8.0 ms) than for neurons with a BF of 50.1-60 kHz (79% between 4.0 and 6.0 ms). Our study of echolocation calls and auditory response properties of IC neurons suggests that the IC of P. abramus can effectively process emitted pulses and echoes during hunting.