Patterns of effective connectivity during memory encoding and retrieval differ between patients with mild cognitive impairment and healthy older adults.
Patterns of effective connectivity during memory encoding and retrieval differ between patients with mild cognitive impairment and healthy older adults.
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DOI：
10.1016/j.neuroimage.2015.10.002
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发表时间：
2016-01-01
期刊：
影响因子：
5.7
通讯作者：
Sathian K
中科院分区：
文献类型：
--
作者：
Hampstead BM;Khoshnoodi M;Yan W;Deshpande G;Sathian K
先前的研究表明，介导成功的记忆编码和检索的神经网络存在相当大的重叠。然而，人们对人类大脑的相关区域在这些不同的记忆阶段如何相互作用，或者这种相互作用如何受到记忆缺陷的影响知之甚少，而记忆缺陷是轻度认知障碍（MCI）的特征，这种情况通常先于阿尔茨海默病引起的痴呆症发生。在这里，我们采用多变量格兰杰因果关系分析，使用推断神经元时间序列的自回归模型，该模型是通过对测量的血氧水平依赖（BOLD）时间序列数据的血流动力学响应函数进行解卷积而获得的，以便检查 MCI 患者和可比较的健康老年人在成功编码和/或检索对象位置关联期间大脑区域之间的有效连接。在编码过程中，健康老年人表现出左半球主导模式，其中额下交界处、前顶内沟（可能涉及顶叶眼区）和后扣带皮层驱动大多数左半球区域和几乎每个测试的右半球区域的激活。这些区域是额顶叶网络的一部分，该网络介导自上而下的认知控制，并与成功的记忆形成有关。相比之下，在 MCI 患者中，右额眼区域驱动了所检查的每个左半球区域的激活，这表明依赖于更基本的视觉搜索过程。健康老年人的记忆检索主要由右侧海马体驱动，右侧丘脑前核和右侧额下沟的贡献较小，这与认为海马体对于成功记忆检索至关重要的理论模型一致。 MCI 患者的模式有所不同，其中右额下交界处和右前丘脑驱动成功的记忆检索，反映了这些患者特有的海马功能障碍。这些发现表明，MCI 患者和健康老年人之间的神经网络相互作用存在显着差异。未来的工作将调查记忆认知康复对这些连接模式的影响。
Previous research has shown that there is considerable overlap in the neural networks mediating successful memory encoding and retrieval. However, little is known about how the relevant human brain regions interact during these distinct phases of memory or how such interactions are affected by memory deficits that characterize mild cognitive impairment (MCI), a condition that often precedes dementia due to Alzheimer’s disease. Here we employed multivariate Granger causality analysis using autoregressive modeling of inferred neuronal time series obtained by deconvolving the hemodynamic response function from measured blood oxygenation level- dependent (BOLD) time series data, in order to examine the effective connectivity between brain regions during successful encoding and/or retrieval of object location associations in MCI patients and comparable healthy older adults. During encoding, healthy older adults demonstrated a left hemisphere dominant pattern where the inferior frontal junction, anterior intraparietal sulcus (likely involving the parietal eye fields), and posterior cingulate cortex drove activation in most left hemisphere regions and virtually every right hemisphere region tested. These regions are part of a frontoparietal network that mediates top-down cognitive control and is implicated in successful memory formation. In contrast, in the MCI patients, the right frontal eye field drove activation in every left hemisphere region examined, suggesting reliance on more basic visual search processes. Retrieval in the healthy older adults was primarily driven by the right hippocampus with lesser contributions of the right anterior thalamic nuclei and right inferior frontal sulcus, consistent with theoretical models holding the hippocampus as critical for the successful retrieval of memories. The pattern differed in MCI patients, in whom the right inferior frontal junction and right anterior thalamus drove successful memory retrieval, reflecting the characteristic hippocampal dysfunction of these patients. These findings demonstrate that neural network interactions differ markedly between MCI patients and healthy older adults. Future efforts will investigate the impact of cognitive rehabilitation of memory on these connectivity patterns.
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