Shared inputs, entrainment, and desynchrony in elliptic bursters: from slow passage to discontinuous circle maps

TL;DR

This paper investigates how pulsatile inputs influence synchrony and desynchrony in elliptic bursters, revealing conditions for chaos or phase-locking through analytical and numerical methods involving circle maps.

Contribution

It extends phase reduction techniques to include varied input strengths, resulting in a circle map framework with discontinuities, applied to both normal form and biophysical neuron models.

Findings

Inputs can induce chaotic or periodic responses depending on their period and amplitude.

Discontinuities in the circle map are crucial for understanding entrainment and desynchrony.

Slow-passage effects through bifurcations significantly influence the response dynamics.

Abstract

What input signals will lead to synchrony vs. desynchrony in a group of biological oscillators? This question connects with both classical dynamical systems analyses of entrainment and phase locking and with emerging studies of stimulation patterns for controlling neural network activity. Here, we focus on the response of a population of uncoupled, elliptically bursting neurons to a common pulsatile input. We extend a phase reduction from the literature to capture inputs of varied strength, leading to a circle map with discontinuities of various orders. In a combined analytical and numerical approach, we apply our results to both a normal form model for elliptic bursting and to a biophysically-based neuron model from the basal ganglia. We find that, depending on the period and amplitude of inputs, the response can either appear chaotic (with provably positive Lyaponov exponent for the associated circle maps), or periodic with a broad range of phase-locked periods. Throughout, we discuss the critical underlying mechanisms, including slow-passage effects through Hopf bifurcation, the role and origin of discontinuities, and the impact of noise