GABA能回路在听皮层神经元频率调谐中的作用

The role of GABAergic circuits in the frequency tuning of auditory cortical neurons

为了解神经抑制在听中枢神经元频率调谐过程中的作用,本研究采用多管玻璃微电极胞外记录单单位反应的方法观察了去r-氨基丁酸能抑制后大棕蝠(Eptesicusfuscus)听皮层神经元频率调谐特性的变化,结果显示:(1)97.9%的神经元频率调谐曲线扩宽,Qn值下降(p<0.0001);(2)绝大部分神经元的最小阈值下降(p<0.0001);(3)兴奋性调谐曲线面积增加(p<0.0001).该结果提供了GABA能回路参与蝙蝠听皮层神经元频率调谐的直接证据.

Frequency tuning is one of the most fundamental functions of the auditory system. To better understand the function of neural inhibition in frequency tuning of central auditory neurons, the characteristics of frequency tuning of auditory cortical neurons after GABAergic disinhibition were studied using standard extracellular single-unit recording technique that was combined with multibarrel glass electrodes for microiontophoresis. The results showed: 1) Frequency tuning curves of 97.9% neurons broadened and Qn values decreased (p<0.000 1, ttest); 2) The minimum threshold (MT) dropped 6.4±3.4 dB SPL (m±sd) on an average(p<0.000 1, ttest); 3) The areas of frequency tuning curves increased (p<0.000 1, ttest). Our date provided a direct testimony that GABAergic circuits operate to sharpen frequency tuning of auditory cortical neurons in bats.