GABAergic Hub Neurons Orchestrate Synchrony in Developing Hippocampal Networks

TLDR

Theoretical models predict that highly connected hub neurons strongly influence synchronization of spiking activity, yet experimental evidence for such hubs is lacking. The authors used high-resolution two‑photon calcium imaging to record spontaneous calcium fluctuations in hundreds of neurons and determine their relative timing. Functional connectivity maps identified GABAergic hub neurons with extensive axonal arbors that orchestrated network synchrony, and manipulating their spike activity modulated spontaneous network synchronizations and giant depolarizing potentials. Bonifazi et al.

Abstract

Coordinating Neuronal Assemblies Theoretical models predict the existence of so-called hub neurons—highly connected cells that strongly influence the synchronization of spiking activity in a large group of neurons. However, experimental evidence for the existence of these neuronal hubs is lacking. Bonifazi et al. (p. 1419 ) used high-resolution, two-photon calcium imaging to measure spontaneous calcium fluctuations in hundreds of neurons simultaneously and determined the relative timing of these fluctuations. Examination of functional connectivity maps, based on temporal correlation measurements, revealed a subpopulation of GABAergic hub neurons displaying a remarkably widespread axonal arborization that orchestrated network synchrony in developing hippocampal networks. Spontaneous network synchronizations in developing hippocampus caused giant depolarizing potentials in individual neurons, and manipulating the spike activity in potential hub cells influenced network activity.