Medical Psychological Institute,Second Xiangya Hospital,Central South University,Changsha,People's Republic of China.
School of Life Sciences,Fudan University,Shanghai,People's Republic of China.
Psychol Med. 2016 Apr;46(6):1211-24. doi: 10.1017/S0033291715002755. Epub 2016 Jan 8.
A large-scale network named the default mode network (DMN) dynamically cooperates and competes with an external attention system (EAS) to facilitate various cognitive functioning that is prominently impaired in schizophrenia. However, it is unclear whether the cognitive deficit in schizophrenia is related to the disrupted competition and/or cooperation between these two networks.
A total of 35 schizophrenia patients and 30 healthy controls were scanned using gradient-echo echo-planar imaging during n-back working memory (WM) processing. Brain activities of the DMN and EAS were measured using general linear modelling of the functional magnetic resonance imaging data. Dynamic interaction between the DMN and EAS was decomposed into two directions using Granger causality analysis.
We observed a significant failure of DMN suppression in patients with schizophrenia, which was significantly related to WM/attentional deficit. Granger causality modelling showed that in healthy controls, while the EAS inhibitorily influenced the DMN, the DMN exerted an 'excitatory' or cooperative influence back on the EAS, especially in those with lower WM accuracy. In schizophrenia, this 'excitatory' DMN→EAS influence within the reciprocal EAS-DMN loop was significantly reduced, especially in patients with WM/attentional deficit.
The dynamic interaction between the DMN and EAS is likely to be comprised of both competitive and cooperative influences. In healthy controls, both the 'inhibitory' EAS→DMN interaction and 'excitatory' DMN→EAS interaction are correlated with WM performance. In schizophrenia, reduced 'cooperative' influence from the DMN to dorsal nodes of the EAS occurs in the context of non-suppression of the DMN and may form a possible pathophysiological substrate of WM deficit and attention disorder.
一个名为默认模式网络（DMN）的大规模网络与外部注意系统（EAS）动态合作和竞争，以促进各种认知功能，这些功能在精神分裂症中明显受损。然而，精神分裂症的认知缺陷是否与这两个网络之间竞争和/或合作的破坏有关尚不清楚。
使用梯度回波回波平面成像，在 n-back 工作记忆（WM）处理期间对 35 名精神分裂症患者和 30 名健康对照者进行扫描。使用功能磁共振成像数据的广义线性模型测量 DMN 和 EAS 的大脑活动。使用格兰杰因果关系分析将 DMN 和 EAS 之间的动态相互作用分解为两个方向。
我们观察到精神分裂症患者的 DMN 抑制明显失败，这与 WM/注意力缺陷显著相关。格兰杰因果关系模型表明，在健康对照组中，EAS 抑制性地影响 DMN，而 DMN 对 EAS 产生“兴奋”或合作影响，尤其是在 WM 准确性较低的情况下。在精神分裂症中，这种互惠的 EAS-DMN 环路内的“兴奋”DMN→EAS 影响显著降低，尤其是在 WM/注意力缺陷的患者中。
DMN 和 EAS 之间的动态相互作用可能包括竞争和合作影响。在健康对照组中，EAS→DMN 的“抑制”相互作用和 DMN→EAS 的“兴奋”相互作用都与 WM 表现相关。在精神分裂症中，DMN 对 EAS 背侧节点的“合作”影响降低，这可能与 DMN 抑制的缺失有关，可能构成 WM 缺陷和注意力障碍的可能病理生理学基础。
