Zhang J P, Jen P H, Sun X
Division of Biological Sciences, University of Missouri-Columbia, 65211, USA.
J Comp Physiol A. 2000 Oct;186(10):913-22. doi: 10.1007/s003590000142.
This study examined if corticofugal modulation of subcortical frequency-tuning curves varied with sound direction. Both excitatory and inhibitory frequency tuning curves of inferior collicular neurons of the big brown bat, Eptesicus fuscus were plotted before and during electrical stimulation in the auditory cortex at two sound directions (contra-40 degrees and ipsi-40 degrees). Most collicular neurons had broader excitatory frequency-tuning curves at contra-40 degrees but had broader inhibitory frequency-tuning curves at ipsi-40 degrees. Cortical electrical stimulation changed the excitatory minimum thresholds of most collicular neurons at a greater degree at ipsi-40 degrees than at contra-40 degrees. However, cortical electrical stimulation produced a greater increase in the sharpness of excitatory frequency-tuning curves of most corticofugally inhibited collicular neurons at contra-40 degrees but produced a greater decrease in the sharpness of excitatory frequency-tuning curves of most corticofugally facilitated collicular neurons at ipsi-40 degrees. Cortical electrical stimulation also produced a greater change in the sharpness of inhibitory frequency-tuning curves of most corticofugally inhibited collicular neurons at contra-40 degrees than at ipsi-40 degrees. Possible mechanisms for this direction-dependent corticofugal modulation of frequency-tuning curves of collicular neurons are discussed.
本研究考察了皮质下频率调谐曲线的皮质离心调制是否随声音方向而变化。在大棕蝠（棕蝠）下丘神经元的兴奋性和抑制性频率调谐曲线在两个声音方向（对侧40度和同侧40度）的听觉皮层电刺激之前和期间进行了绘制。大多数下丘神经元在对侧40度时具有更宽的兴奋性频率调谐曲线，但在同侧40度时具有更宽的抑制性频率调谐曲线。皮层电刺激在同侧40度时比在对侧40度时更大程度地改变了大多数下丘神经元的兴奋性最小阈值。然而，皮层电刺激在对侧40度时使大多数皮质离心抑制的下丘神经元的兴奋性频率调谐曲线的锐度有更大增加，但在同侧40度时使大多数皮质离心易化的下丘神经元的兴奋性频率调谐曲线的锐度有更大降低。皮层电刺激在对侧40度时也比在同侧40度时使大多数皮质离心抑制的下丘神经元的抑制性频率调谐曲线的锐度有更大变化。本文讨论了下丘神经元频率调谐曲线这种方向依赖性皮质离心调制的可能机制。
