Abstract
Firing patterns in the central nervous system often exhibit strong temporal irregularity and heterogeneity in their time averaged response properties. Previous studies suggested that these properties are outcome of an intrinsic chaotic dynamics. Indeed, simplified rate-based large neuronal networks with random synaptic connections are known to exhibit sharp transition from fixed point to chaotic dynamics when the synaptic gain is increased. However, the existence of a similar transition in neuronal circuit models with more realistic architectures and firing dynamics has not been established. In this work we investigate rate based dynamics of neuronal circuits composed of several subpopulations and random connectivity. Nonzero connections are either positive-for excitatory neurons, or negative for inhibitory ones, while single neuron output is strictly positive; in line with known constraints in many biological systems. Using Dynamic Mean Field Theory, we find the phase diagram depicting the regimes of stable fixed point, unstable dynamic and chaotic rate fluctuations. We characterize the properties of systems near the chaotic transition and show that dilute excitatory-inhibitory architectures exhibit the same onset to chaos as a network with Gaussian connectivity. Interestingly, the critical properties near transition depend on the shape of the single- neuron input-output transfer function near firing threshold. Finally, we investigate network models with spiking dynamics. When synaptic time constants are slow relative to the mean inverse firing rates, the network undergoes a sharp transition from fast spiking fluctuations and static firing rates to a state with slow chaotic rate fluctuations. When the synaptic time constants are finite, the transition becomes smooth and obeys scaling properties, similar to crossover phenomena in statistical mechanics
Highlights
The firing patterns of circuits in the central nervous system often exhibit a high level of temporal irregularity
II, we introduce a general architecture for random recurrent networks with multiple subpopulations, obeying smooth rate-based dynamics
The dynamic mean field theory (DMFT) is more complex than the single-population network, we show that the two-population network exhibits a transition from fixed point to chaos that is similar to that of the single-population case
Summary
The firing patterns of circuits in the central nervous system often exhibit a high level of temporal irregularity. Several theoretical studies explored the emergence of temporal irregularity and, in particular, chaotic dynamics in neuronal networks These investigations focused on two types of models: rate-based models with Gaussian connections and spiking dynamics of sparsely connected excitatory-inhibitory networks.
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