Dacosta-Aguayo Rosalia, Graña Manuel, Iturria-Medina Yasser, Fernández-Andújar Marina, López-Cancio Elena, Cáceres Cynthia, Bargalló Núria, Barrios Maite, Clemente Immaculada, Toran Pera, Forés Rosa, Dávalos Antoni, Auer Tibor, Mataró Maria
Department of Psychiatry and Clinical Psychobiology, University of Barcelona, Barcelona, Spain; Group of Computational Intelligence, Department of CCIA, University of the Basque Country UPV/EHU, San Sebastian, Spain.
Hum Brain Mapp. 2015 Feb;36(2):577-90. doi: 10.1002/hbm.22648. Epub 2014 Oct 16.
Resting-state studies conducted with stroke patients are scarce. The study of brain activity and connectivity at rest provides a unique opportunity for the investigation of brain rewiring after stroke and plasticity changes. This study sought to identify dynamic changes in the functional organization of the default mode network (DMN) of stroke patients at three months after stroke. Eleven patients (eight male and three female; age range: 48-72) with right cortical and subcortical ischemic infarctions and 17 controls (eleven males and six females; age range: 57-69) were assessed by neurological and neuropsychological examinations and scanned with resting-state functional magnetic ressonance imaging. First, we explored group differences in functional activity within the DMN by means of probabilistic independent component analysis followed by a dual regression approach. Second, we estimated functional connectivity between 11 DMN nodes both locally by means of seed-based connectivity analysis, as well as globally by means of graph-computation analysis. We found that patients had greater DMN activity in the left precuneus and the left anterior cingulate gyrus when compared with healthy controls (P < 0.05 family-wise error corrected). Seed-based connectivity analysis showed that stroke patients had significant impairment (P = 0.014; threshold = 2.00) in the connectivity between the following five DMN nodes: left superior frontal gyrus (lSFG) and posterior cingulate cortex (t = 2.01); left parahippocampal gyrus and right superior frontal gyrus (t = 2.11); left parahippocampal gyrus and lSFG (t = 2.39); right parietal and lSFG (t = 2.29). Finally, mean path length obtained from graph-computation analysis showed positive correlations with semantic fluency test (r(s) = 0.454; P = 0.023), phonetic fluency test (r(s) = 0.523; P = 0.007) and the mini mental state examination (r(s) = 0.528; P = 0.007). In conclusion, the ability to regulate activity of the DMN appears to be a central part of normal brain function in stroke patients. Our study expands the understanding of the changes occurring in the brain after stroke providing a new avenue for investigating lesion-induced network plasticity.
针对中风患者开展的静息态研究较少。对静息状态下的大脑活动和连通性进行研究，为探究中风后脑重塑及可塑性变化提供了独特契机。本研究旨在确定中风患者在中风三个月后默认模式网络（DMN）功能组织的动态变化。对11例（8例男性，3例女性；年龄范围：48 - 72岁）右侧皮质及皮质下缺血性梗死患者和17例对照者（11例男性，6例女性；年龄范围：57 - 69岁）进行了神经学和神经心理学检查，并采用静息态功能磁共振成像进行扫描。首先，我们通过概率独立成分分析及双回归方法探究DMN内功能活动的组间差异。其次，我们通过基于种子点的连通性分析在局部估计11个DMN节点之间的功能连通性，并通过图形计算分析在全局进行估计。我们发现，与健康对照相比，患者在左侧楔前叶和左侧前扣带回有更强的DMN活动（P < 0.05，经家族性错误校正）。基于种子点的连通性分析显示，中风患者在以下五个DMN节点之间的连通性存在显著损伤（P = 0.014；阈值 = 2.00）：左侧额上回（lSFG）与后扣带回皮质（t = 2.01）；左侧海马旁回与右侧额上回（t = 2.11）；左侧海马旁回与lSFG（t = 2.39）；右侧顶叶与lSFG（t = 2.29）。最后，通过图形计算分析得到的平均路径长度与语义流畅性测试（r(s) = 0.454；P = 0.023）、语音流畅性测试（r(s) = 0.523；P = 0.007）及简易精神状态检查（r(s) = 0.528；P = 0.007）呈正相关。总之，调节DMN活动的能力似乎是中风患者正常脑功能的核心部分。我们的研究扩展了对中风后脑内变化的理解，为研究损伤诱导的网络可塑性提供了新途径。
