Balanced Synaptic Input Shapes the Correlation between Neural Spike Trains

Stimulus properties, attention, and behavioral context influence correlations between the spike times produced by a pair of neurons. However, the biophysical mechanisms that modulate these correlations are poorly understood. With a combined theoretical and experimental approach, we show that the rate of balanced excitatory and inhibitory synaptic input modulates the magnitude and timescale of pairwise spike train correlation. High rate synaptic inputs promote spike time synchrony rather than long timescale spike rate correlations, while low rate synaptic inputs produce opposite results. This correlation shaping is due to a combination of enhanced high frequency input transfer and reduced firing rate gain in the high input rate state compared to the low state. Our study extends neural modulation from single neuron responses to population activity, a necessary step in understanding how the dynamics and processing of neural activity change across distinct brain states.

刺激特性、注意力以及行为情境会影响成对神经元产生的锋电位时序（spike times）之间的相关性。然而，调控此类相关性的生物物理机制仍未得到充分阐释。本研究通过理论与实验相结合的手段，证实平衡的兴奋性与抑制性突触输入的速率，可调控成对锋电位序列（spike train）相关性的强度与时域尺度。高频率突触输入会促进锋电位时序同步性，而非长时域尺度的锋电位速率相关性；低频率突触输入则会产生相反的效应。此类相关性的调控效应源于：相较于低输入速率状态，高输入速率状态下存在增强的高频输入传递特性，同时伴随锋电位发放速率增益的降低。本研究将神经调控的研究范畴从单个神经元响应拓展至群体神经活动，这是理解不同脑状态下神经活动的动力学与信息处理方式如何变化的必要环节。