Excitation-Inhibition Balance, Neural Criticality, and Activities in Neuronal Circuits.

Neural activities in local circuits exhibit complex and multilevel dynamic features. Individual neurons spike irregularly, which is believed to originate from receiving balanced amounts of excitatory and inhibitory inputs, known as the excitation-inhibition balance. The spatial-temporal cascades of clustered neuronal spikes occur in variable sizes and durations, manifested as neural avalanches with scale-free features. These may be explained by the neural criticality hypothesis, which posits that neural systems operate around the transition between distinct dynamic states. Here, we summarize the experimental evidence for and the underlying theory of excitation-inhibition balance and neural criticality. Furthermore, we review recent studies of excitatory-inhibitory networks with synaptic kinetics as a simple solution to reconcile these two apparently distinct theories in a single circuit model. This provides a more unified understanding of multilevel neural activities in local circuits, from spontaneous to stimulus-response dynamics.

Visual Evoked Response Modulation Occurs in a Complementary Manner Under Dynamic Circuit Framework.

The steady-state visual-evoked potential (SSVEP) induced by the periodic visual stimulus plays an important role in vision research. An increasing number of studies use the SSVEP to manipulate intrinsic oscillation and further regulate test performance. However, how the internal state modulates fundamental properties of the SSVEP remains poorly understood. Here, we identified a multiscale computational model to investigate the neural mechanism underlying low-frequency SSVEP modulation. We found that intrinsic alpha oscillation mirroring the circuit coupling state modulates the SSVEP in a complementary manner at different spatial levels, which unifies prior seemingly contradictory observations. Specifically, our model demonstrates that the laminar-specific organization induced by intercortical communication possibly underlies the commonly observed inverse SSVEP-alpha relation and that the individual peak alpha frequency (iPAF) transformation characterizing local coupling contributes to the individual-specific resonance frequency responses. Our dynamic circuit framework builds a link between SSVEP gain modulation and intrinsic alpha oscillation and paves the way for the further reconstruction of SSVEP global dynamics.