Background 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. Method 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. Results 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' DMNEAS influence within the reciprocal EAS-DMN loop was significantly reduced, especially in patients with WM/attentional deficit. Conclusions 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' EASDMN interaction and excitatory' DMNEAS 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.
[1]Cent S Univ, Xiangya Hosp 2, Inst Med Psychol, Changsha 410011, Hunan, Peoples R China.
[2]Cent S Univ, Xiangya Hosp 2, Inst Mental Hlth, Changsha 410011, Hunan, Peoples R China.
[3]Fudan Univ, Sch Life Sci, Shanghai 200433, Peoples R China.
[4]Fudan Univ, Sch Math Sci, Ctr Computat Syst Biol, Shanghai 200433, Peoples R China.
[5]Univ Western Ontario, Dept Psychiat, Schulich Sch Med & Dent, London, ON N6A 3K7, Canada.
[6]Univ Western Ontario, Robarts Res Inst, London, ON, Canada.
[7]Shanghai Ctr Math Sci, Shanghai, Peoples R China.
[8]Univ Warwick, Dept Comp Sci, Coventry CV4 7AL, W Midlands, England.
[9]Fudan Univ, Collaborat Innovat Ctr Brain Sci, Shanghai 200433, Peoples R China.
[10]Cent S Univ, State Key Lab Med Genet, Changsha 410011, Hunan, Peoples R China.
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