Involvement of GABA-mediated inhibition in shaping the frequency selectivity of neurons in the inferior colliculus of the big brown bat, Eptesicus fuscus.
Involvement of GABA-mediated inhibition in shaping the frequency selectivity of neurons in the inferior colliculus of the big brown bat, Eptesicus fuscus.
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DOI：
10.4077/cjp.2009.amh002
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发表时间：
2009-02
期刊：
影响因子：
--
通讯作者：
Feijian Wu;P. Jen
中科院分区：
文献类型：
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作者：
Feijian Wu;P. Jen
在中枢听觉信号处理中，神经抑制对提高听觉神经元的选择性起着重要作用。本研究利用前向掩蔽范式和荷包牡丹碱研究了GABA介导的抑制作用在蝙蝠下丘(IC)神经元频率选择性形成中的作用。在每个研究过程中，我们用一对电极记录了两个IC神经元，并相互研究了作为探测一个神经元反应的声音是否可以作为掩蔽者影响另一个配对神经元的频率调谐曲线(FTC)。在所记录的33对IC神经元中，这种前向掩蔽范式使29对(88%)IC神经元的FTC变尖，4对(12%)IC神经元的FTC变宽。FTC的锐化程度随着记录深度的增加以及每对IC神经元最佳频率和记录深度的不同而减小。尽管荷包牡丹碱的应用扩大了所有IC神经元的FTC，但前向掩蔽仍然使大多数IC神经元的FTC变得尖锐。这些数据表明，在频率分析过程中，IC神经元的群体是高度相关的，其中一些IC神经元的频率选择性通过抑制而得到改善，而另一些IC神经元的频率敏感度则通过激发来增强。讨论了这些数据与声信号处理相关的生物学意义。
In central auditory signal processing, neural inhibition plays an important role in sharpening the selectivity of auditory neurons. The present study examines the involvement of GABA-mediated inhibition in shaping the frequency selectivity of neurons in the bat inferior colliculus (IC) using forward masking paradigm and bicuculline application. At each study session, we recorded two IC neurons with a pair of electrodes and reciprocally studied whether a sound that served as a probe to elicit response of one neuron might serve as a masker to affect the frequency tuning curve (FTC) of the other paired neuron. Among the 33 pairs of IC neurons recorded, this forward masking paradigm produces sharpening of the FTC in 29 (88%) pairs of IC neurons and broadening of the FTC in 4 (12%) pairs of IC neurons. The degree of sharpening of FTC decreases with recording depth as well as with the difference in the best frequency and recording depth between each pair of IC neurons. Although bicuculline application broadens the FTC of all IC neurons, forward masking still produces sharpening of the FTC in most IC neurons. These data suggest that population of IC neurons are highly correlated during frequency analysis such that frequency selectivity of some groups of IC neurons is improved through inhibition while the spectrum of frequency sensitivity of other groups of IC neurons is enhanced through excitation. Biological significance of these data relevant to acoustic signal processing is discussed.