Effect of autaptic synapse on signal transmission performance of dressed Hodgkin-Huxley neuron

Abstract

Astrocytes, which have complex relationships with neurons, are the most important biological arguments that support neurons in the performance of cognitive functions. Another important biological argument in nervous systems is autapse, a special type of synapse through which the neuron provides feedback to itself. It is well known that both astrocyte and autapse modulate neuron dynamics and they affect memory functions. Considering the idea that some cognitive brain functions occur through chaotic firings, more complex models in which structures such as astrocytes and autaptic synapses are included in the system are needed to better understand the neural system. In this study, the signal detection abilities of astrocyte-dressed Hodgkin-Huxley neurons which have electrical, excitatory, and inhibitory chemical autaptic synapses are examined separately under chaotic environmental conditions. The results show that astrocyte-supported neurons, especially those with electrical and excitatory-chemical autapse, exhibit a strong chaotic resonance for appropriate parameters. After the autaptic synapse, the astrocyte is a second modulator of the neuron's signal detection success. Additionally, it is observed that autaptic time delay is more effective than autaptic conductance in modulating the signal transmission success of the neuron. For all autapse types, the parameter values at which the supportive effect of the astrocyte in the model is obtained are presented. Furthermore, multiple chaotic resonance is detected in neurons with electrical and excitatory chemical autapse when the autaptic delay is equal to integer multiples of the weak signal period. This is observed for neurons with inhibitory chemical autapse when half of the weak signal period is added to whole multiples of the weak signal period. We hope that our findings will shed light on the chaotic environment behavior of complex nervous systems interacting with astrocytes and autapse.