Abstract
The time scale of neuronal network dynamics is determined by synaptic interactions and neuronal signal integration, both of which occur on the time scale of milliseconds. Yet many behaviors like the generation of movements or vocalizations of sounds occur on the much slower time scale of seconds. Here we ask the question of how neuronal networks of the brain can support reliable behavior on this time scale. We argue that excitable neuronal assemblies with spike-frequency adaptation may serve as building blocks that can flexibly adjust the speed of execution of neural circuit function. We show in simulations that a chain of neuronal assemblies can propagate signals reliably, similar to the well-known synfire chain, but with the crucial difference that the propagation speed is slower and tunable to the behaviorally relevant range. Moreover we study a grid of excitable neuronal assemblies as a simplified model of the somatosensory barrel cortex of the mouse and demonstrate that various patterns of experimentally observed spatial activity propagation can be explained.
Highlights
Reliable propagation of activity is necessary for processing and transmitting sensory signals in the brain
Models of activity propagation in cortical networks have often been based on feedforward structures
We propose a model of activity propagation, called excitation chain, which does not need such a feedforward structure
Summary
Reliable propagation of activity is necessary for processing and transmitting sensory signals in the brain. The synfire chain consists of groups of spiking neurons connected in a feedforward architecture [1,2,3,4] potentially embedded in recurrent networks [5, 6]. Rate propagation models [6,7,8,9] use a similar feedforward architecture, but instead of spikes they propagate fluctuations of the firing rate. In a synfire chain the refractory behavior of neurons after firing a spike is the crucial element of stable activity propagation [10]. Reliable neuronal firing patterns compatible with synfire chains have been observed in area HVC of the song-bird [14], while the statistical significance of synfire chains in cortical neurons is questionable [15]. Systems of interacting synfire chains were used for building a large-scale model of cortex [18, 19]
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