Background and purpose

Cognitive impairment is a common consequence of stroke, and the rewiring of the surviving brain circuits might contribute to cognitive recovery. Studies investigating how the functional connectivity of networks change across time and whether their remapping relates to cognitive recovery in stroke patients are scarce. We aimed to investigate whether resting-state functional connectivity was associated with cognitive performance in stroke patients and if any alterations in these networks were correlated with cognitive recovery.

Methods

Using an fMRI ROI-ROI approach, we compared the ipsilesional, contralesional and interhemispheric functional connectivity of three resting-state networks involved in cognition – the Default Mode (DMN), Salience (SN) and Central Executive Networks (CEN), in subacute ischemic stroke patients (time 1, n = 37, stroke onset: 24.32 ± 7.44 days, NIHSS: 2.66 ± 3.45) with cognitively healthy controls (n = 20). Patients were reassessed six months after the stroke event (time 2, n = 20, stroke onset: 182.05 ± 8.17 days) to verify the subsequent reorganization of functional connections and whether such reorganization was associated with cognitive recovery.

Results

At time 1, patients had weaker interhemispheric connectivity in the DMN than controls; better cognitive performance at time 1 was associated with stronger interhemispheric and ipsilesional DMN connectivity, and weaker contralesional SN connectivity. At time 2, there were no changes in functional connectivity in stroke patients, compared to time 1. Better cognitive recovery measured at time 2 (time 2 – time 1) was associated with stronger functional connectivity in the DMN, and weaker interhemispheric subacute connectivity in the SN, both from time 1.

Conclusions

Stroke disrupts the functional connectivity of the DMN, not only at the lesioned hemisphere but also between hemispheres. Six months after the stroke event, we could not detect the remapping of networks. Cognitive recovery was associated with the connectivity of both the DMN and SN of time 1. Our findings may be helpful for facilitating further understanding of the potential mechanisms underlying post-stroke cognitive performance.

中文翻译：

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亚急性功能连接与中风后六个月的认知恢复相关

背景和目的

认知障碍是中风的常见后果，幸存的脑回路重新布线可能有助于认知恢复。很少有研究调查网络的功能连接性如何随时间变化以及它们的重新映射是否与中风患者的认知恢复有关。我们旨在调查静息状态功能连接是否与中风患者的认知表现有关，以及这些网络中的任何变化是否与认知恢复有关。

方法

使用fMRI ROI-ROI方法，我们比较了亚急性缺血中参与认知的三种静止状态网络（默认模式（DMN），显着性（SN）和中央执行网络（CEN））的同侧，对侧和半球功能连接性中风患者（时间1，n = 37，中风发作：24.32±7.44天，NIHSS：2.66±3.45），其认知健康对照（n = 20）。中风事件发生后六个月（时间2，n = 20，中风发作：182.05±8.17天）对患者进行了重新评估，以验证其后功能连接的重组以及这种重组是否与认知恢复有关。

结果

在时间1，DMN患者的半球间连接性较对照组弱；在时间1处更好的认知表现与更强的半球形和同侧DMN连接以及更弱的对侧SN连接相关。与时间1相比，在时间2，卒中患者的功能连通性没有变化。在时间2（时间2 –时间1）测得更好的认知恢复与DMN中较强的功能连通性以及较弱的半球间亚急性连通性相关。 SN，均从时间1开始。

结论

中风不仅在病变半球而且在半球之间都破坏了DMN的功能连接。中风事件发生六个月后，我们无法检测到网络的重新映射。认知恢复与时间1的DMN和SN的连通性相关。我们的发现可能有助于促进对卒中后认知表现的潜在机制的进一步理解。