Multiple firing coherence resonances in excitatory and inhibitory coupled neurons

TL;DR

This study explores how delay-induced coherence resonances in coupled Hodgkin-Huxley neurons depend on synaptic types and delays, revealing complex patterns that can optimize neuronal spiking regularity.

Contribution

It uncovers the conditions under which multiple firing coherence resonances occur in delay-coupled neurons with inhibitory and excitatory synapses, highlighting new mechanisms for neuronal regularity.

Findings

Multiple firing coherence resonances occur with tuned delays and strong coupling.

Denser resonance patterns emerge with inhibitory-only synapses.

Robustness of resonances persists despite delays, noise, and network size.

Abstract

The impact of inhibitory and excitatory synapses in delay-coupled Hodgkin--Huxley neurons that are driven by noise is studied. If both synaptic types are used for coupling, appropriately tuned delays in the inhibition feedback induce multiple firing coherence resonances at sufficiently strong coupling strengths, thus giving rise to tongues of coherency in the corresponding delay-strength parameter plane. If only inhibitory synapses are used, however, appropriately tuned delays also give rise to multiresonant responses, yet the successive delays warranting an optimal coherence of excitations obey different relations with regards to the inherent time scales of neuronal dynamics. This leads to denser coherence resonance patterns in the delay-strength parameter plane. The robustness of these findings to the introduction of delay in the excitatory feedback, to noise, and to the number of coupled neurons is determined. Mechanisms underlying our observations are revealed, and it is suggested that the regularity of spiking across neuronal networks can be optimized in an unexpectedly rich variety of ways, depending on the type of coupling and the duration of delays.