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。

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.

Neurons in the auditory cortex (AC) receive convergent excitatory and inhibitory inputs from the lower auditory nuclei. Interaction between these two opposing inputs shapes different response properties of AC neurons. In this study, we examined how this interaction might affect the frequency tuning curves (FTCs), number of impulses and latency of AC neurons in the big brown bat, Eptesicus fuscus, using a probe (excitatory tone) and a masker (inhibitory tone) under different stimulation conditions. Excitatory FTCs of AC neurons were either V-shaped, closed (i.e. upper threshold) or double-peaked. Inhibitory FTCs were obtained either at both flanks or only at the low or high flank of excitatory FTCs. Application of bicuculline, an antagonist for Q-aminobutyric acid A receptors, produced expansion of excitatory FTCs into predrug inhibitory FTCs. Inhibition of probeelicited responses occurred when a masker was presented at certain intertone intervals. Maximal inhibition typically took place when a masker was presented within 4 ms prior to the probe. During maximal inhibition, a neuron had the minimal number of impulses and the longest response latency. Inhibition became stronger with increasing masker intensity but became weaker with increasing intertone interval. Biological significance of these data is discussed.

Using bats as a model auditory system, we studied corticofugal control of auditory sensitivity of neurons in the inferior colliculus. We demonstrate for the first time that the corticocollicular pathway continuously regulates acoustic signal processing in the inferior coiliculus by increasing the threshold, reducing the auditory spatial response area, and sharpening the frequency tuning curve of recorded inferior collicular neurons. Regulation of auditory sensitivity of recorded inferior collicular neurons was observed when the corticocollicular pathway was activated by electrical stimulation in the auditory cortex. The effect of this corticofugal regulation of auditory sensitivity in inferior collicular neurons can also be produced by ionophoretical application of GABA to the collicular recording site. This regulation of ascending acoustic information by commands originating from higher brain centers may provide the bat with a mechanism to actively control acoustic signal processing and thus optimize acoustic signal analysis.

This article reviews our recent studies of brief and short-term corticofugal modulation of signal processing in the central nucleus of the inferior colliculus (ICc) by electrical stimulation in the primary auditory cortex (AC). When cortical electrical stimulation was synchronized with an acoustic stimulus, auditory responses of ICc neurons were either inhibited or facilitated and the modulative effect typically vanished within 5^10 s after the stimulation. When cortical electrical stimulation synchronized with an acoustic stimulus was repetitively delivered for 30 min, corticofugal modulation of collicular responses typically persisted up to 40 min after the stimulation. In the frequency domain, cortical electrical stimulation decreased the excitatory frequency tuning curves (FTCs) and asymmetrically increased the lateral inhibitory FTCs of corticofugally inhibited ICc neurons but produced the opposite effect on corticofugally facilitated ICc neurons. Cortical electrical stimulation facilitated auditory responses of neurons in the external nucleus of the inferior colliculus (ICx) while electrical stimulation in the ICx decreased auditory responses of ICc neurons. Auditory responses of simultaneously recorded ICx and ICc neurons varied in opposite ways during cortical electrical stimulation or drug application to recorded ICx neurons. In the amplitude domain, cortical electrical stimulation compressed rate amplitude functions so as to increase the slope of rate^amplitude functions of ICc neurons. This modulative effect decreased with increasing stimulus amplitude. The possible biological relevance of these findings is discussed.