Biophysical Mechanism And Cognitive Functions Of Interaction Between Default Mode Network And Working Memory Network

Default mode network is a functional brain network with a unique neural activity pattern that shows higher activity in resting states but lower activity in task states.This unique pattern has been proved to relate with higher cognitions such as learning,memory and decision-making.But neural mechanisms of interactions between the default network and the task-related network are still poorly understood.In this paper,a theoretical model of coupling default mode network(DMN)and working memory network(WMN)is proposed.The WMN and DMN both consist of excitatory and inhibitory neurons connected by AMPA,NMDA,GABA synapses,and couple with each other only by excitatory synapses.This model is implemented to simulate a complete working memory process containing encoding,maintenance and retrieval phases.In order to reach this goal,it is needed to clarify how the network switches different phases of working memory.Results have shown that:1)AMPA channels could produce significant synchronous oscillations in population neurons,which is beneficial to realize oscillation pattern changes in the both WMN and DMN.2)Different NMDA conductance between the networks could generate multiple neural activity modes in the whole network,which may be an important mechanism to switch states of the networks between three different phases of working memory.3)The number of sequentially memorized stimuli was related to the energy consumption determined by the network's internal parameters,and the DMN contributed to a more stable working memory process.4)Finally,this model demonstrated that,in three phases of working memory,different memory phases corresponded to different functional connections between the DMN and WMN.Coupling strengths that measured these functional connections differed in terms of phase synchronization.Our research has found that the negative and positive correlation between the WMN and DMN were integrable in the model.Phase synchronization characteristics of contained energy were consistent with the conversion of negative and positive correlations between the WMN and DMN observed in fMRI experiments.