Research On Synaptic Modulation Mechanism Of Resonance Of Complex Neuronal Networks

The brain consists of a large number of different types of neurons, each of which interacts with others through synaptic connections, so that advanced functions of brain are generated. The dynamical behavior of neuronal networks is closely related to brain functions. Particularly, resonance is a key mechanism of information transmission and coding in neuronal networks. Synapse and its plasticity play an important role in modulating neural network structure and function. Therefore, the modulation of synapses on resonance is studied in small-world neuronal networks.The small-world neuronal networks with hybrid electrical and chemical synapses are established to investigate the effect of different synapses on stochastic resonance(SR). The numerical results show that:(i) chemical synapses are more likely to induce SR than electrical ones. With the increase of probability of chemical synapses, the optimal noise intensity to evoke SR decreases, and the intensity of resonance reduces significantly. It is confirmed that, chemical coupling is advantageous to the detection of weak signal, while the subthreshold input is well transmitted through electrical synapses.(ii) Time delays in information transmission is an inherent characteristic of neural systems. It can evidently trigger the occurrence of multiple stochastic resonances. The networked SR is largely enhanced only when the delay is the integral multiples of period of input signal.(iii) The small-world topology also has important effect on the stochastic resonance. The capacity of weak signal detection and transmission can be improved by appropriately improve the network randomness.Based on Hebbian learning mechanism, the adaptive small-world neuronal network is constructed to investigate the impact of spike-timing-dependent plasticity(STDP) on network structure and dynamics. The numerical results show that:(i) STDP can adjusting the coupling strength between neurons according to the spike timing of pre- and post-synaptic one, which eventually leads to the reduce of network average coupling strength and depresses the synchronization and regularity of spiking neurons.(ii) There exists an optimal noise intensity to induce the phenomenon of SR in adaptive neural systems. The adjustment of STDP can result in the enhancement of a part of synaptic strength, by which the capacity of weak signal detection and transmission is improved significantly.(iii) There exists an optimal small-world topology enhancing the phenomenon of stochastic resonance and coherence resonance induced by STDP.The obtained results confirm the modulation of synapses on the structure and behavior of complex neuronal networks; also provide a theoretical basis for the improvement of electromagnetic stimulation on brain function.