The frustrated brain: From dynamics on motifs to communities and networks

TL;DR

This paper explores how brain network motifs influence zero-lag synchrony, revealing that resonance pairs promote stability while frustrated loops enable metastability, which may support flexible cognitive functions.

Contribution

It uncovers how basic network motifs modulate synchrony patterns, integrating resonance and frustration effects to explain brain dynamics across scales.

Findings

Resonance pairs promote stable zero-lag synchrony.

Frustrated motifs enable metastable synchrony configurations.

Synchronization variability depends on delay, network size, and coupling strength.

Abstract

Cognitive function depends on an adaptive balance between flexible dynamics and integrative processes in distributed cortical networks. Patterns of zero-lag synchrony likely underpin numerous perceptual and cognitive functions. Synchronization fulfils integration by reducing entropy, whilst adaptive function mandates that a broad variety of stable states be readily accessible. Here, we elucidate two complementary influences on patterns of zero-lag synchrony that derive from basic properties of brain networks. First, mutually coupled pairs of neuronal subsystems -- resonance pairs -- promote stable zero-lag synchrony amongst the small motifs in which they are embedded, and whose effects can propagate along connected chains. Second, frustrated closed-loop motifs disrupt synchronous dynamics, enabling metastable configurations of zero-lag synchrony to coexist. We document these two complementary influences in small motifs and illustrate how these effects underpin stable versus metastable phase-synchronization patterns in prototypical modular networks and in large-scale cortical networks of the macaque (CoCoMac). We find that the variability of synchronization patterns depends on the inter-node time delay, increases with the network size, and is maximized for intermediate coupling strengths. We hypothesize that the dialectic influences of resonance versus frustration may form a dynamic substrate for flexible neuronal integration, an essential platform across diverse cognitive processes.