Abstract
Despite the current debate about the computational role of experimentally observed precise spike patterns it is still theoretically unclear under which conditions and how they may emerge in neural circuits. Here, we study spiking neural networks with non-additive dendritic interactions that were recently uncovered in single-neuron experiments. We show that supra-additive dendritic interactions enable the persistent propagation of synchronous activity already in purely random networks without superimposed structures and explain the mechanism underlying it. This study adds a novel perspective on the dynamics of networks with nonlinear interactions in general and presents a new viable mechanism for the occurrence of patterns of precisely timed spikes in recurrent networks.
Highlights
Patterns of spikes that are precisely timed within the millisecond range have been investigated and observed in a series of neurophysiological studies [1,2,3,4,5,6,7,8,9]. This supports the ongoing debate whether cortical neurons are capable of precisely coordinating the timing of their action potentials across recurrent networks and whether only the neurons’ firing rate or the precise timing of their spikes encode key information that is intimately related to external stimuli and internal events [2,3,10,11,12,13,14]
Recent neurophysiological experiments found that under certain conditions the neuronal dendrites (branched projections of the neuron that transmit inputs from other neurons to the cell body) process input spikes in a nonlinear way: If the inputs arrive within a time window of a few milliseconds, the dendrite can actively generate a dendritic spike that propagates to the neuronal soma and leads to a nonlinearly amplified response
We find that synchronous spiking activity may robustly propagate through the network, even if it exhibits purely random connectivity without superimposed structures. Such propagation may contribute to the generation of spike patterns that are currently discussed to encode information about internal states and external stimuli in neural circuits
Summary
Patterns of spikes that are precisely timed within the millisecond range have been investigated and observed in a series of neurophysiological studies [1,2,3,4,5,6,7,8,9]. Possible explanation for the occurrence of precisely coordinated spiking is the existence of excitatorily coupled feedforward structures, ‘synfire-chains’, which are superimposed on a network of otherwise random connectivity, e.g. through strongly enhanced synaptic connectivity [10,15,16,17,18]. Under certain conditions, these additional feed-forward structures enable the persistent propagation of groups of spiking activity that is synchronous on a time scale of down to one millisecond [17,19,20,21,22,23,24]. Other studies proposed that asynchronous propagation along paths with matching inhomogeneous delays [25] or the dynamics of local recurrent networks [26,27] might underlie precisely timed spike patterns
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