Wu Chung Hsin, Jen Philip H-S
Division of Biological Sciences and Interdisciplinary Neuroscience Program, University of Missouri-Columbia, Columbia, MO 65211, USA.
J Comp Physiol A Neuroethol Sens Neural Behav Physiol. 2006 Sep;192(9):985-1002. doi: 10.1007/s00359-006-0133-6.
When insectivorous bats such as Eptesicus fuscus emit ultrasonic signals and analyze the returning echoes to hunt insects, duration selectivity of auditory neurons plays an important role in echo recognition. The success of prey capture indicates that they can effectively encode progressively shortened echo duration throughout the hunting process. The present study examines the echo duration selectivity of neurons in the central nucleus of the bat inferior colliculus (IC) under stimulation conditions of single pulses and pulse-echo (P-E) pairs. This study also examines the role of gamma-aminobutyric acid (GABA)ergic inhibition in shaping echo duration selectivity of IC neurons. The data obtained show that the echo duration selectivity of IC neurons is sharper when determined with P-E pairs than with single pulses. Echo duration selectivity also sharpens with shortening of pulse duration and P-E gap. Bicuculline application decreases and GABA application increases echo duration selectivity of IC neurons. The degree of change in echo duration selectivity progressively increases with shortening of pulse duration and P-E gap during bicuculline application while the opposite is observed during the GABA application. These data indicate that the GABAergic inhibition contributes to sharpening of echo duration selectivity of IC neurons and facilitates echo recognition by bats throughout different phases of hunting.
当食虫蝙蝠（如棕蝠）发出超声波信号并分析返回的回声以捕食昆虫时，听觉神经元的持续时间选择性在回声识别中起着重要作用。猎物捕获的成功表明它们能够在整个捕猎过程中有效地编码逐渐缩短的回声持续时间。本研究在单脉冲和脉冲-回声（P-E）对的刺激条件下，研究了蝙蝠下丘（IC）中央核中神经元的回声持续时间选择性。本研究还考察了γ-氨基丁酸（GABA）能抑制在塑造IC神经元回声持续时间选择性中的作用。获得的数据表明，用P-E对测定时，IC神经元的回声持续时间选择性比用单脉冲测定时更敏锐。回声持续时间选择性也随着脉冲持续时间和P-E间隔的缩短而增强。应用荷包牡丹碱会降低IC神经元的回声持续时间选择性，而应用GABA则会增加其回声持续时间选择性。在应用荷包牡丹碱期间，随着脉冲持续时间和P-E间隔的缩短，回声持续时间选择性的变化程度逐渐增加，而在应用GABA期间则观察到相反的情况。这些数据表明，GABA能抑制有助于增强IC神经元回声持续时间选择性，并在蝙蝠捕猎的不同阶段促进回声识别。
