Jen P H, Chen Q C, Sun X D
Division of Biological Sciences, University of Missouri-Columbia 65211, USA.
J Comp Physiol A. 1998 Dec;183(6):683-97. doi: 10.1007/s003590050291.
Under free-field stimulation conditions, corticofugal regulation of auditory sensitivity of neurons in the central nucleus of the inferior colliculus of the big brown bat, Eptesicus fuscus, was studied by blocking activities of auditory cortical neurons with Lidocaine or by electrical stimulation in auditory cortical neuron recording sites. The corticocollicular pathway regulated the number of impulses, the auditory spatial response areas and the frequency-tuning curves of inferior colliculus neurons through facilitation or inhibition. Corticofugal regulation was most effective at low sound intensity and was dependent upon the time interval between acoustic and electrical stimuli. At optimal inter-stimulus intervals, inferior colliculus neurons had the smallest number of impulses and the longest response latency during corticofugal inhibition. The opposite effects were observed during corticofugal facilitation. Corticofugal inhibitory latency was longer than corticofugal facilitatory latency. Iontophoretic application of gamma-aminobutyric acid and bicuculline to inferior colliculus recording sites produced effects similar to what were observed during corticofugal inhibition and facilitation. We suggest that corticofugal regulation of central auditory sensitivity can provide an animal with a mechanism to regulate acoustic signal processing in the ascending auditory pathway.
在自由场刺激条件下，通过用利多卡因阻断听觉皮层神经元的活动或在听觉皮层神经元记录部位进行电刺激，研究了大棕蝠（棕蝠）下丘中央核中神经元听觉敏感性的皮质离心调节。皮质-丘系通路通过促进或抑制作用调节下丘神经元的冲动数量、听觉空间反应区域和频率调谐曲线。皮质离心调节在低声强时最为有效，并且依赖于声刺激和电刺激之间的时间间隔。在最佳刺激间隔时，在下丘神经元的皮质离心抑制期间，冲动数量最少且反应潜伏期最长。在皮质离心促进期间观察到相反的效果。皮质离心抑制潜伏期比皮质离心促进潜伏期长。向下丘记录部位离子电泳施加γ-氨基丁酸和荷包牡丹碱产生的效果与在皮质离心抑制和促进期间观察到的效果相似。我们认为，中枢听觉敏感性的皮质离心调节可以为动物提供一种机制，以调节听觉上行通路中的声信号处理。
