GABA能抑制环路对神经元信噪比的调节作用

The regulatory role of GABAergic inhibition loop on signal to noise ratio of neurons

目的研究初级视皮层内抑制性环路与神经元反应信噪比之间的关系。方法通过胞外局部微电泳GABA及其受体拮抗剂Bicuculline改变神经元的抑制水平,并采用胞外单细胞技术记录神经元对视觉刺激所发放的动作电位。本文分析并比较了65个猫的初级视皮层神经元3种信噪比SNR、SNR_1、mSNR在给药前后的变化。结果当施加GABA,自发放幅度降低,细胞的信噪比增加;当施加Bicuculline,白发放幅度增高,细胞的信噪比降低。结论神经系统内的抑制环路活动水平与神经元反应信噪比密切相关,部分提高抑制水平在一定程度上可增加神经元信噪比。提示可通过向特定脑区给予抑制性物质,以改善神经系统由于抑制性输入不足导致的功能衰退。

Objective To investigate the contribution of inhibitory circuit to the signal to noise ratio （SNR） of neurons. Methods We eleetrophoretically applied the inhibitory transmitter GABA and the GABAA antagonist Bicuculline to increase/decrease the level of inhibition imposed on the neuron and extracellularly recorded single unit response of that neuron to visual stimuli. Sixty-five neurons from Area 17 in anesthetized cats were included in our analysis. SNR, SNR1, and mSNR were compared with or without GABA and Bicuculline administration. Results GABA decreased the amplitude of spontaneous activity and increased the SNR,while Bieuculline increased the amplitude of spontaneous activity and decreased the SNR. Conclusions The activity level of inhibitory circuit in neural system correlated closely with the SNR of neurons and enhancing the inhibition level increased the SNR to some extent,which indicated that delivery of inhibitory substance into special brain area might improve neural system ＇ s function due to insufficiency of inhibitory input, especially aging.