Effects of dynamic synapses on noise-delayed response latency of a single neuron

TL;DR

This study explores how dynamic synapses influence noise-delayed response latency in a Hodgkin-Huxley neuron, revealing new double NDD phenomena due to synaptic depression and facilitation effects.

Contribution

It introduces the first observation of double NDD behavior in neuronal response latency caused by dynamic synaptic mechanisms.

Findings

Classical NDD observed with static synapses as a function of presynaptic firing rate.

Dynamic synapses with depression and facilitation produce double NDD behavior.

Synaptic facilitation promotes DNDD, while depression favors single NDD.

Abstract

Noise-delayed decay (NDD) phenomenon emerges when the first-spike latency of a periodically forced stochastic neuron exhibits a maximum for a particular range of noise intensity. Here, we investigate the latency response dynamics of a single Hodgkin-Huxley neuron that is subject to both a suprathreshold periodic stimulus and a background activity arriving through dynamic synapses. We study the first spike latency response as a function of the presynaptic firing rate f. This constitutes a more realistic scenario than previous works, since f provides a suitable biophysically realistic parameter to control the level of activity in actual neural systems. We first report on the emergence of classical NDD behavior as a function of f for the limit of static synapses. Secondly, we show that when short-term depression and facilitation mechanisms are included at synapses, different NDD features can be found due to the their modulatory effect on synaptic current fluctuations. For example a new intriguing double NDD (DNDD) behavior occurs for different sets of relevant synaptic parameters. Moreover, depending on the balance between synaptic depression and synaptic facilitation, single NDD or DNDD can prevails, in such a way that synaptic facilitation favors the emergence of DNDD whereas synaptic depression favors the existence of single NDD. This is the first time it has been reported the existence of DNDD effect in response latency dynamics of a neuron.