PT  - JOURNAL ARTICLE
AU  - Alberto Romagnoni
AU  - Matthew Colonnese
AU  - Jonathan Touboul
AU  - Boris Gutkin
TI  - Development of inhibitory synaptic delay drives maturation of thalamocortical network dynamics
AID  - 10.1101/296673
DP  - 2018 Jan 01
TA  - bioRxiv
PG  - 296673
4099  - http://biorxiv.org/content/early/2018/04/06/296673.short
4100  - http://biorxiv.org/content/early/2018/04/06/296673.full
AB  - As the nervous system develops, changes take place across multiple levels of organization. Cellular and circuit properties often mature gradually, while emergent properties of network dynamics can change abruptly. Here, we use mathematical models, supported by experimental measurements, to investigate a sudden transition in the spontaneous activity of the rodent visual cortex from an oscillatory regime to a stable asynchronous state that prepares the developing system for vision. In particular, we explore the possible role played by data-constrained changes in the amplitude and timing of inhibition. To this end, we extend the standard Wilson and Cowan model to take into account the relative timescale and rate of the population response for inhibitory and excitatory neurons. We show that the progressive sharpening of inhibitory neuron population responses during development is crucial in determining network dynamics. In particular, we show that a gradual change in the ratio of excitatory to inhibitory response time-scales drives a bifurcation of the network activity regime, namely a sudden transition from high-amplitude oscillations to an active non-oscillatory state. Thus a gradual speed-up of the inhibitory transmission onset alone can account for the sudden and sharp modification of thalamocortical activities observed experimentally. Our results show that sudden functional changes in the neural network responses during development do not necessitate dramatic changes in the underlying cell and synaptic properties: rather slow developmental changes in cells electrophysiology and transmission can drive rapid switches in cortical dynamics associated to the onset of functional sensory responses.