Hillary Frank G, Roman Cristina A, Venkatesan Umesh, Rajtmajer Sarah M, Bajo Ricardo, Castellanos Nazareth D
Department of Psychology, Pennsylvania State University.
Department of Mathematics, Pennsylvania State University.
Neuropsychology. 2015 Jan;29(1):59-75. doi: 10.1037/neu0000110. Epub 2014 Jun 16.
In the cognitive and clinical neurosciences, the past decade has been marked by dramatic growth in a literature examining brain "connectivity" using noninvasive methods. We offer a critical review of the blood oxygen level dependent functional MRI (BOLD fMRI) literature examining neural connectivity changes in neurological disorders with focus on brain injury and dementia. The goal is to demonstrate that there are identifiable shifts in local and large-scale network connectivity that can be predicted by the degree of pathology. We anticipate that the most common network response to neurological insult is hyperconnectivity but that this response depends upon demand and resource availability.
To examine this hypothesis, we initially reviewed the results from 1,426 studies examining functional brain connectivity in individuals diagnosed with multiple sclerosis, traumatic brain injury, mild cognitive impairment, and Alzheimer's disease. Based upon inclusionary criteria, 126 studies were included for detailed analysis.
RESULTS from 126 studies examining local and whole brain connectivity demonstrated increased connectivity in traumatic brain injury and multiple sclerosis. This finding is juxtaposed with findings in mild cognitive impairment and Alzheimer's disease where there is a shift to diminished connectivity as degeneration progresses.
This summary of the functional imaging literature using fMRI methods reveals that hyperconnectivity is a common response to neurological disruption and that it may be differentially observable across brain regions. We discuss the factors contributing to both hyper- and hypoconnectivity results after neurological disruption and the implications these findings have for network plasticity.
在认知神经科学和临床神经科学领域，过去十年以使用非侵入性方法研究大脑“连接性”的文献急剧增长为特征。我们对利用血氧水平依赖性功能磁共振成像（BOLD fMRI）研究神经障碍（重点是脑损伤和痴呆）中神经连接变化的文献进行了批判性综述。目的是证明局部和大规模网络连接存在可通过病理程度预测的可识别变化。我们预计，对神经损伤最常见的网络反应是连接增强，但这种反应取决于需求和资源可用性。
为检验这一假设，我们首先回顾了1426项研究的结果，这些研究考察了被诊断为多发性硬化症、创伤性脑损伤、轻度认知障碍和阿尔茨海默病的个体的大脑功能连接。根据纳入标准，126项研究被纳入详细分析。
126项研究局部和全脑连接性的结果表明，创伤性脑损伤和多发性硬化症中连接性增加。这一发现与轻度认知障碍和阿尔茨海默病的发现形成对比，在这些疾病中，随着神经退行性变的进展，连接性会转向降低。
使用fMRI方法对功能成像文献的这一总结表明，连接增强是对神经功能破坏的常见反应，并且在不同脑区可能有不同表现。我们讨论了神经功能破坏后导致连接增强和减弱结果的因素，以及这些发现对网络可塑性的影响。
