Biophysical mechanism of the interaction between default mode network and working memory network

Yue Yuan,Xiaochuan Pan,Rubin Wang

doi:10.1007/s11571-021-09674-1

Yue Yuan, Xiaochuan Pan + Show 1 more

Open Access

https://doi.org/10.1007/s11571-021-09674-1

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Abstract

Default mode network (DMN) is a functional brain network with a unique neural activity pattern that shows high activity in resting states but low 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 the 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 are coupled with each other only by excitatory synapses. This model is implemented to demonstrate dynamical processes in a working memory task containing encoding, maintenance and retrieval phases. Simulated results have shown that: (1) AMPA channels could produce significant synchronous oscillations in population neurons, which is beneficial to change oscillation patterns in the 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. Phase synchronization characteristics of the contained energy were consistent with the observations of negative and positive correlations between the WMN and DMN reported in referenced fMRI experiments. The results suggested that the coupled interaction between the WMN and DMN played important roles in working memory.

Highlights

The brain’s default mode network (DMN) was originally identified in a meta-analysis that mapped brain regions were more active in passive as compared to active tasks (Buckner et al 2008)
We found negative or positive correlations between the working memory network (WMN) and Default mode network (DMN) during different phases in a complete working memory process, which was consistent with observations reported in a functional magnetic resonance imaging (fMRI) study (Piccoli et al 2015)
Previous studies have shown that the TPN–TNN model based on synaptic mechanism could simulate the anticorrelation between the DMN and WMN (Cheng et al 2020)

Summary

Introduction

The brain’s default mode network (DMN) was originally identified in a meta-analysis that mapped brain regions were more active in passive as compared to active tasks (often referred to as task-induced deactivation) (Buckner et al 2008). When people are meditating, daydreaming, recalling the past, planning for the future etc., the brain is Physiological experiments showed that the low firing mode of the DMN in task states was an incidental phenomenon of task-state brain activity, and played an extremely important role in maintaining normal cognitions and psychological states (Hu et al 2017; Greicius and Menon 2004). Insufficient inhibition of the DMN in task states would reduce activity in the dorsal attention network, resulting in memory loss and cognitive impairment. Some functional magnetic resonance imaging (fMRI) studies have shown that the physiological inhibition of the DMN in healthy brains was stronger than that in patients with ADHD, contributing to better accomplishment of attention tasks in healthy individuals (Uddin et al 2008). Behavioral research demonstrated that the hyperactivity of the DMN make it difficult for patients to transfer attention from the internal meditation to external stimuli, which induced the loss of working memory and mood control (Figueroa et al 2017)

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