Cliques of a few functional hub neurons control the whole network activity

Recent experiments have shown that single neuron stimulation can impact network dynamics in immature and adult neuronal circuits. Here we show a novel mechanism which can explain the peculiar role played by a few specific neurons in promoting/arresting the activity of the whole population. For this purpose, we consider a standard neuronal network model, with short-term synaptic plasticity, whose population activity is characterized by peaks of synchronous activity (population bursts). We analyse networks with different architectures, mimicking also different stages of maturation, and we report the conditions that lead to the emergence of a self-organized pool of a few neurons, responsible for the build-up of the population bursts. In particular the collective events of synchronous activity are driven by the sequential and coordinated activation of these peculiar critical neurons arranged in a clique. These neurons are hubs in a functional sense, as the played role is not related to the intrinsic degree of connectivity but to the order of firing before the ignition of the PB. The existence of this peculiar pool of neurons has the consequence that perturbations of even one single neuron of the clique, through the deletion from the network or the injection of a current, strongly impact the collective dynamics and bring even to the arrest of the bursting activity.