Inhibition‘s blowing. It was thought that neural activity in the immature brain was controlled by a small population of neurons which, from their dominant position, were overheading the construction of the brain circuits. But the demonstration that these neurons had a decisive influence in the living pups was still lacking. Here, the authors finally demonstrate formally that the so-called hub neurons dimension the activation of neuron assemblies during spikes of activity, generated either internally or by sensory inputs, through their inhibition capacity. (IB)

Scientific abstract: Spontaneous synchronous activity is a hallmark of developing brain circuits and promotes their formation. Ex vivo, synchronous activity was shown to be orchestrated by a sparse population of highly connected GABAergic ‘hub’ neurons. The recent development of all-optical methods to record and manipulate neuronal activity in vivo now offers the unprecedented opportunity to probe the existence and function of hub cells in vivo. Using calcium imaging, connectivity analysis and holographic optical stimulation, we show that single GABAergic, but not glutamatergic, neurons influence population dynamics in the barrel cortex of non-anaesthetized mouse pups. Single GABAergic cells mainly exert an inhibitory influence on both spontaneous and sensory-evoked population bursts. Their network influence scales with their functional connectivity, with highly connected hub neurons displaying the strongest impact. We propose that hub neurons function in tailoring intrinsic cortical dynamics to external sensory inputs.

The authors:  Y Bollmann*, L Modol*, T Tressard, A Vorobyev, R Dard, S Brustlein, R Sims, I Bendifallah, E Leprince , V de Sars, E Ronzitti, A Baude, H Adesnik, M Picardo, JC Platel, V Emiliani, D Angulo-Garcia & R Cossart

published in Nature Neuroscience, September 2023