Construction And Analysis Of The Suprachiasmatic Nucleus’ Directed Network Based On Transfer Entropy

In the Suprachiasmatic Nucleus of the mammalian brain,there is an endogenous clock,called SCN(the Suprachiasmatic Nucleus),which regulates biological physiological and behavioral activities.SCN consists of about 20,000 neurons that are coupled into a network by neurotransmitters and oscillate synchronously to produce uniform and robust periodic signals.From the perspective of complex network,SCN network is composed of neuron nodes and edges formed by the coupling of neurotransmitters between neurons.Therefore,how to determine the coupling relationship between neurons,how to construct the network based on the coupling relationship,and what the nature of the constructed network is,are the key points of research.In this paper,the method of transfer entropy is used to calculate the coupling strength between neurons,and then the directed network is constructed according to the edge-connected method,and the network properties are statistically analyzed.First,directed networks are established based on the experimental data.The first step is to detrend the experimental data with first-order difference and to calculate the coupling strength between the neuron oscillators by using the method of transfer entropy.In the second step,an appropriate threshold is adopted to select the edge,and a directed network is preliminarily constructed.Then,isolated neuron nodes are connected to form a directed network by coupling all neurons.These directed networks correspond to five SCN slices(i.e.3×5=15 networks)in three experimental stages,each of which contains roughly hundreds of neuron nodes.Secondly,network properties are analyzed according to the constructed directed network,including path length,clustering coefficient,node degree distribution and heterogeneity of node degree.It is found that the degree distribution of network nodes is similar to the power-law distribution at each experimental stage,and the corresponding test results are given.Moreover,all SCN networks are heterologous networks,that nodes with high degree of degree prefer to connect nodes with low degree.And heterologous coefficients are defined to describe the degree of preference.At the same time,it was found that during the application of tetrodotoxin,the small-world characteristics of SCN network were weakened,and the network disassortativity coefficient was reduced.Finally,linear regression is used to check the correlation between the above network properties and oscillator synchronization.It is found that the disassortativity coefficient is the network property that has the greatest influence on oscillator synchronization.And the heterozygosity coefficient of the network is positively correlated with the degree of oscillator synchronization.Then,we used the Poincaré Mode to verify this result by numerical simulation.Therefore,this paper suggests that the heterologous SCN network can play a better role in the regulation of rhythm,which is more conducive to the synchronization of the neuron vibrators,so as to maintain a stable rhythm.This research not only reveals the specific topological properties of the SCN network,but also analyzes the corresponding changes in the topological properties of different experimental stages.This explains the relationship between SCN network structure and network function to a certain extent,provides some reference for studying SCN network and inspiration for further revealing the evolution of SCN network.