Network bursting dynamics in excitatory cortical neuron cultures results from the combination of different adaptive mechanism
Network bursting dynamics in excitatory cortical neuron cultures results from the combination of different adaptive mechanism
Citació
- Masquelier T, Deco G. Network bursting dynamics in excitatory cortical neuron cultures results from the combination of different adaptive mechanism. PLoS ONE. 2013;8(10): e75824. DOI: 10.1371/journal.pone.0075824
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In the brain, synchronization among cells of an assembly is a common phenomenon, and thought to be functionally /nrelevant. Here we used an in vitro experimental model of cell assemblies, cortical cultures, combined with numerical/nsimulations of a spiking neural network (SNN) to investigate how and why spontaneous synchronization occurs. In order to/ndeal with excitation only, we pharmacologically blocked GABAAergic transmission using bicuculline. Synchronous events in/ncortical cultures tend to involve almost every cell and to display relatively constant durations. We have thus named these/n‘‘network spikes’’ (NS). The inter-NS-intervals (INSIs) proved to be a more interesting phenomenon. In most cortical cultures/nNSs typically come in series or bursts (‘‘bursts of NSs’’, BNS), with short (,1 s) INSIs and separated by long silent intervals/n(tens of s), which leads to bimodal INSI distributions. This suggests that a facilitating mechanism is at work, presumably/nshort-term synaptic facilitation, as well as two fatigue mechanisms: one with a short timescale, presumably short-term/nsynaptic depression, and another one with a longer timescale, presumably cellular adaptation. We thus incorporated these/nthree mechanisms into the SNN, which, indeed, produced realistic BNSs. Next, we systematically varied the recurrent/nexcitation for various adaptation timescales. Strong excitability led to frequent, quasi-periodic BNSs (CV,0), and weak/nexcitability led to rare BNSs, approaching a Poisson process (CV,1). Experimental cultures appear to operate within an/nintermediate weakly-synchronized regime (CV,0.5), with an adaptation timescale in the 2–8 s range, and well described by/na Poisson-with-refractory-period model. Taken together, our results demonstrate that the INSI statistics are indeed/ninformative: they allowed us to infer the mechanisms at work, and many parameters that we cannot access experimentally.