Objective To investigate the contribution of inhibitory circuit to the signal to noise ratio (SNR) of neurons.Methods We electrophoretically 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 Bicuculline 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.
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