Zhang Guo, Yu Ke, Wang Tao, Chen Ting-Ting, Yuan Wang-Ding, Yang Fan, Le Zi-Wei, Guo Shi-Qi, Xue Ying-Yu, Chen Song-An, Yang Zhe, Liu Feng, Cropper Elizabeth C, Weiss Klaudiusz R, Jing Jian
State Key Laboratory of Pharmaceutical Biotechnology, Institute for Brain Sciences, Collaborative Innovation Center of Chemistry for Life Sciences, Jiangsu Engineering Research Center for MicroRNA Biology and Biotechnology, Advanced Institute for Life Sciences, School of Life Sciences, Nanjing University, Nanjing, Jiangsu 210023, China.
National Laboratory of Solid State Microstructures, Department of Physics, Institute for Brain Sciences, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, Jiangsu 210093, China.
Sci Adv. 2020 Jun 19;6(25). doi: 10.1126/sciadv.aba4856. Print 2020 Jun.
Behavioral variability often arises from variable activity in the behavior-generating neural network. The synaptic mechanisms underlying this variability are poorly understood. We show that synaptic noise, in conjunction with weak feedforward excitation, generates variable motor output in the feeding system. A command-like neuron (CBI-10) triggers rhythmic motor programs more variable than programs triggered by CBI-2. CBI-10 weakly excites a pivotal pattern-generating interneuron (B34) strongly activated by CBI-2. The activation properties of B34 substantially account for the degree of program variability. CBI-10- and CBI-2-induced EPSPs in B34 vary in amplitude across trials, suggesting that there is synaptic noise. Computational studies show that synaptic noise is required for program variability. Further, at network state transition points when synaptic conductance is low, maximum program variability is promoted by moderate noise levels. Thus, synaptic strength and noise act together in a nonlinear manner to determine the degree of variability within a feedforward network.
行为变异性通常源于行为产生神经网络中的可变活动。然而，对于这种变异性背后的突触机制，我们却知之甚少。我们发现，突触噪声与微弱的前馈兴奋相结合，会在进食系统中产生可变的运动输出。一个类似命令的神经元（CBI - 10）触发的节律性运动程序比CBI - 2触发的程序更具变异性。CBI - 10微弱地兴奋一个关键的模式生成中间神经元（B34），而CBI - 2能强烈激活该神经元。B34的激活特性在很大程度上决定了程序的变异程度。CBI - 10和CBI - 2在B34中诱发的兴奋性突触后电位（EPSP）在不同试验中的幅度有所变化，这表明存在突触噪声。计算研究表明，程序变异性需要突触噪声。此外，在网络状态转换点，当突触电导较低时，适度的噪声水平会促进最大程度的程序变异性。因此，突触强度和噪声以非线性方式共同作用，决定前馈网络内的变异程度。
