Synaptic Plasticity in Correlated Balanced Networks

TL;DR

This paper develops a comprehensive theory of how synaptic plasticity interacts with correlated activity in balanced neural networks, showing that balance can be maintained and that correlations influence weight evolution and network stability.

Contribution

It introduces a general framework for understanding plasticity in balanced networks, revealing how correlations affect weight dynamics and stability under various plasticity rules.

Findings

Balance can be maintained under plasticity-induced weight changes.

Correlations in input influence synaptic weight evolution.

Weights tend to converge to a stable manifold depending on initial conditions.

Abstract

The dynamics of local cortical networks are irregular, but correlated. Dynamic excitatory--inhibitory balance is a plausible mechanism that generates such irregular activity, but it remains unclear how balance is achieved and maintained in plastic neural networks. In particular, it is not fully understood how plasticity induced changes in the network affect balance, and in turn, how correlated, balanced activity impacts learning. How does the dynamics of balanced networks change under different plasticity rules? How does correlated spiking activity in recurrent networks change the evolution of weights, their eventual magnitude, and structure across the network? To address these questions, we develop a general theory of plasticity in balanced networks. We show that balance can be attained and maintained under plasticity induced weight changes. We find that correlations in the input mildly, but significantly affect the evolution of synaptic weights. Under certain plasticity rules, we find an emergence of correlations between firing rates and synaptic weights. Under these rules, synaptic weights converge to a stable manifold in weight space with their final configuration dependent on the initial state of the network. Lastly, we show that our framework can also describe the dynamics of plastic balanced networks when subsets of neurons receive targeted optogenetic input.