Phase changes in neuronal postsynaptic spiking due to short term plasticity

In the brain, the postsynaptic response of a neuron to time-varying inputs is determined by the interaction of presynaptic spike times with the short-term dynamics of each synapse. For a neuron driven by stochastic synapses, synaptic depression results in a quite different postsynaptic response to a large population input depending on how correlated in time the spikes across individual synapses are. Here we show using both simulations and mathematical analysis that not only the rate but the phase of the postsynaptic response to a rhythmic population input varies as a function of synaptic dynamics and synaptic configuration. Resultant phase leads may compensate for transmission delays and be predictive of rhythmic changes. This could be particularly important for sensory processing and motor rhythm generation in the nervous system.

在大脑中，神经元对时变输入的突触后反应（postsynaptic response）由突触前脉冲时刻（presynaptic spike times）与各突触的短时程动力学（short-term dynamics）之间的相互作用所决定。对于受随机突触（stochastic synapses）驱动的神经元而言，突触压抑（synaptic depression）会根据单个突触脉冲的时间相关性强弱，使得群体输入引发的突触后反应呈现显著差异。本文通过模拟实验与数学分析两种方法证实：针对节律性群体输入（rhythmic population input），其引发的突触后反应不仅速率会随突触动力学与突触配置（synaptic configuration）的变化而变化，反应的相位同样会随之改变。由此产生的相位超前可补偿突触传递延迟（transmission delays），并可用于预测节律性的信号变化。这一发现对于神经系统内的感觉处理（sensory processing）与运动节律生成（motor rhythm generation）具有尤为重要的意义。