Functional Connectivity in Mild Cognitive Impairment During a Memory Task: Implications for the Disconnection Hypothesis
Functional Connectivity in Mild Cognitive Impairment During a Memory Task: Implications for the Disconnection Hypothesis
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DOI：
10.3233/jad-2010-100177
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发表时间：
2010-01-01
影响因子：
4
通讯作者：
del-Pozo, Francisco
中科院分区：
文献类型：
--
作者：
Bajo, Ricardo;Maestu, Fernando;del-Pozo, Francisco
轻度认知功能障碍（MCI）被认为是介于健康老龄化和痴呆之间的一种中间状态。早期阿尔茨海默病的特征是解剖连接的早期损伤和突触的进行性丧失，这表明MCI也可能是一种断开综合征。在这里，我们比较了在记忆任务中，脑磁图记录的MCI患者（22例）和健康对照组（19例）脑信号的同步程度。基于非线性动力学系统理论的同步性指标Likestival被用来衡量功能连通性。在记忆任务期间，患者在左和右前颞额区域（在所有研究的频带中）和γ频带中的后部区域之间显示出比健康对照组更高的半球间同步。另一方面，从健康对照组的连接模式表明两个集群的较高的同步，左颞叶传感器和中央通道之间的另一个。这两种信号在所有频段都有发现。在伽马波段，对照组在中央-后通道和前-后通道之间显示出比MCI患者更高的同步化Likewise值，并且在后部区域中显示出高同步化。大脑半球间同步值的增加可能反映了MCI患者记忆网络效率不足的代偿机制。因此，这些连接概况仅部分支持MCI作为断开综合征的想法，因为患者显示长距离半球间连接增加，但前后功能连接减少。
Mild cognitive impairment (MCI) has been considered an intermediate state between healthy aging and dementia. The early damage in anatomical connectivity and progressive loss of synapses that characterize early Alzheimer's disease suggest that MCI could also be a disconnection syndrome. Here, we compare the degree of synchronization of brain signals recorded with magnetoencephalography from patients (22) with MCI with that of healthy controls (19) during a memory task. Synchronization Likelihood, an index based on the theory of nonlinear dynamical systems, was used to measure functional connectivity. During the memory task patients showed higher interhemispheric synchronization than healthy controls between left and right -anterior temporo-frontal regions (in all studied frequency bands) and in posterior regions in the gamma band. On the other hand, the connectivity pattern from healthy controls indicated two clusters of higher synchronization, one among left temporal sensors and another one among central channels. Both of them were found in all frequency bands. In the gamma band, controls showed higher Synchronization Likelihood values than MCI patients between central-posterior and frontal-posterior channels and a high synchronization in posterior regions. The inter-hemispheric increased synchronization values could reflect a compensatory mechanism for the lack of efficiency of the memory networks in MCI patients. Therefore, these connectivity profiles support only partially the idea of MCI as a disconnection syndrome, as patients showed increased long distance inter-hemispheric connections but a decrease in antero-posterior functional connectivity.