Role of inhibitory neurons in temporal correlations of critical and supercritical spontaneous activity

TL;DR

This paper investigates how inhibitory neurons influence temporal correlations in brain activity, revealing their role in oscillatory behaviors and activity bursts in supercritical states, with implications for understanding brain dynamics.

Contribution

It introduces a model with differential recovery rates for excitatory and inhibitory neurons, highlighting inhibitory neurons' impact on correlation oscillations and activity bursts.

Findings

Inhibitory neurons induce oscillatory decay in correlation functions.

Increased inhibition leads to more frequent, smaller activity bursts.

Oscillation frequency depends on inhibitory neuron fraction and connectivity.

Abstract

Experimental and numerical results suggest that the brain can be viewed as a system acting close to a critical point, as confirmed by scale-free distributions of relevant quantities in a variety of different systems and models. Less attention has received the investigation of the temporal correlation functions in brain activity in different, healthy and pathological, conditions. Here we perform this analysis by means of a model with short and long-term plasticity which implements the novel feature of different recovery rates for excitatory and inhibitory neurons, found experimentally. We evidence the important role played by inhibitory neurons in the supercritical state: We detect an unexpected oscillatory behaviour of the correlation decay, whose frequency depends on the fraction of inhibitory neurons and their connectivity degree. This behaviour can be rationalized by the observation that bursts in activity become more frequent and with a smaller amplitude as inhibition becomes more relevant.