Soleimani Behrad, Dallasta Isabella, Das Proloy, Kulasingham Joshua P, Girgenti Sophia, Simon Jonathan Z, Babadi Behtash, Marsh Elisabeth B
Department of Electrical and Computer Engineering, University of Maryland, College Park, MD 20742, USA.
Institute for Systems Research, University of Maryland, College Park, MD 20740, USA.
Brain Commun. 2023 May 6;5(3):fcad149. doi: 10.1093/braincomms/fcad149. eCollection 2023.
Cortical ischaemic strokes result in cognitive deficits depending on the area of the affected brain. However, we have demonstrated that difficulties with attention and processing speed can occur even with small subcortical infarcts. Symptoms appear independent of lesion location, suggesting they arise from generalized disruption of cognitive networks. Longitudinal studies evaluating directional measures of functional connectivity in this population are lacking. We evaluated six patients with minor stroke exhibiting cognitive impairment 6-8 weeks post-infarct and four age-similar controls. Resting-state magnetoencephalography data were collected. Clinical and imaging evaluations of both groups were repeated 6- and 12 months later. Network Localized Granger Causality was used to determine differences in directional connectivity between groups and across visits, which were correlated with clinical performance. Directional connectivity patterns remained stable across visits for controls. After the stroke, inter-hemispheric connectivity between the frontoparietal cortex and the non-frontoparietal cortex significantly increased between visits 1 and 2, corresponding to uniform improvement in reaction times and cognitive scores. Initially, the majority of functional links originated from non-frontal areas contralateral to the lesion, connecting to ipsilesional brain regions. By visit 2, inter-hemispheric connections, directed from the ipsilesional to the contralesional cortex significantly increased. At visit 3, patients demonstrating continued favourable cognitive recovery showed less reliance on these inter-hemispheric connections. These changes were not observed in those without continued improvement. Our findings provide supporting evidence that the neural basis of early post-stroke cognitive dysfunction occurs at the network level, and continued recovery correlates with the evolution of inter-hemispheric connectivity.
皮质缺血性中风会导致认知缺陷，具体情况取决于受影响的脑区。然而，我们已经证明，即使是小的皮质下梗死也可能出现注意力和处理速度方面的困难。症状的出现与病变位置无关，这表明它们源于认知网络的普遍破坏。目前缺乏评估该人群功能连接方向性指标的纵向研究。我们评估了6例中风后6 - 8周出现认知障碍的轻度中风患者和4例年龄相仿的对照组。收集了静息态脑磁图数据。两组的临床和影像学评估在6个月和12个月后重复进行。使用网络局部格兰杰因果关系来确定组间和不同访视之间方向性连接的差异，并将其与临床表型相关联。对照组在不同访视间的方向性连接模式保持稳定。中风后，额顶叶皮质和非额顶叶皮质之间的半球间连接在第1次和第2次访视之间显著增加，这与反应时间和认知评分的一致改善相对应。最初，大多数功能连接起源于病变对侧的非额叶区域，连接到同侧脑区。到第2次访视时，从同侧皮质指向对侧皮质的半球间连接显著增加。在第3次访视时，表现出持续良好认知恢复的患者对这些半球间连接的依赖减少。在没有持续改善的患者中未观察到这些变化。我们的研究结果提供了支持性证据，表明中风后早期认知功能障碍的神经基础发生在网络水平，并且持续恢复与半球间连接的演变相关。
