默认模式网络与任务正网络之间相互拮抗的神经动力学分析

任务正激活与任务负激活的工作机制是认知功能实现的基本要素.这一拮抗关系的失衡或者受损可能会引发一系列严重的退行性神经疾病,然而到目前为止,尚不清楚这种拮抗现象的神经机制.该文基于默认模式网络与任务正网络在突触层面上相互抑制的假设,并结合多种刺激条件下的工作记忆模型,进行了计算机数值模拟.研究结果表明:1)任务正网络与任务负网络之间在神经活动上呈现出拮抗关系; 2)伴随着工作记忆刺激方向数目的增加,任务负网络神经活动的衰减程度会随之增大; 3)当工作记忆相关的脑区其神经活动增加时,任务负网络的神经活动减少;4)并且随着工作记忆任务难度的增加,任务负网络的神经活动会迅速衰减.这些计算结果都与神经科学实验数据是匹配的.由于任务负激活是默认模式网络的主要特征,因此默认模式网络与任务正网络在突触层面上的相互抑制是这两种不同性质网络之间形成拮抗关系的根本原因.

Neurodynamic Analysis of Mutual Antagonism Between Default Mode Networks and Task-Positive Networks

The working mechanism of task-positive activation and task-negative activation is the fundamental element of cognitive function. The imbalance or impairment of this antagonism may induce a series of severe degenerative neurological diseases. However, the neural mechanism of this antagonism is unclear. Based on the mutual synaptic inhibitory assumption for the default mode network and the task-positive network, the numerical simulation of a working memory model was performed under multiple stimuli conditions. The results show that: 1) neural activities of task-positive and task-negative networks appear to antagonize each other; 2) the neural activity decay of the task-negative network will intensify as the count of stimulus directions of working memory increases; 3) the activity of the task-negative network will drop when the neural activity of the brain area related to working memory increases; 4) as the difficulty of working memory rises, the neural activity of the task-negative network will quickly decrease. These computational results match well with the experimental data. Since task-negative activation is the primary property of the default mode network, the mutual synaptic inhibition of default mode and task-positive networks makes the fundamental reason why the antagonism is generated between these 2 networks.