Department of Psychology, Pennsylvania State University, 223 Bruce V. Moore Building, University Park, PA 16802, USA.
Brain. 2011 May;134(Pt 5):1555-70. doi: 10.1093/brain/awr043. Epub 2011 May 13.
There is mounting literature that examines brain activation during tasks of working memory in individuals with neurological disorders such as traumatic brain injury. These studies represent a foundation for understanding the functional brain changes that occur after moderate and severe traumatic brain injury, but the focus on topographical brain-'activation' differences ignores potential alterations in how nodes communicate within a distributed neural network. The present study makes use of the most recently developed connectivity modelling (extended-unified structural equation model) to examine performance during a well-established working-memory task (the n-back) in individuals sustaining moderate and severe traumatic brain injury. The goal is to use the findings observed in topographical activation analysis as the basis for second-level effective connectivity modelling. Findings reveal important between-group differences in within-hemisphere connectivity during task acquisition, with the control sample demonstrating rapid within-left hemisphere connectivity increases and the traumatic brain injury sample demonstrating consistently elevated within-right hemisphere connectivity. These findings also point to important maturational effects from 'early' to 'late' during task performance, including diminished right prefrontal cortex involvement and an anterior to posterior shift in connectivity with increased task exposure. We anticipate that this approach to functional imaging data analysis represents an important future direction for understanding how neural plasticity is expressed in brain disorders.
越来越多的文献研究了神经障碍（如创伤性脑损伤）患者在工作记忆任务中大脑激活的情况。这些研究为理解中度和重度创伤性脑损伤后大脑功能变化奠定了基础，但对脑“激活”差异的关注忽略了在分布式神经网络中节点之间通信方式的潜在变化。本研究利用最近开发的连接建模（扩展统一结构方程模型）来研究中度和重度创伤性脑损伤患者在一项成熟的工作记忆任务（n-back）中的表现。目标是使用拓扑激活分析中观察到的结果作为二级有效连接建模的基础。研究结果显示，在任务获取过程中，左右半球内的连接存在重要的组间差异，对照组表现出快速的左半球内连接增加，而创伤性脑损伤组则表现出持续升高的右半球内连接。这些发现还表明，在任务执行过程中，从“早期”到“晚期”存在重要的成熟效应，包括右前额叶皮层参与度降低，以及随着任务暴露的增加，连接从前到后转移。我们预计，这种功能性成像数据分析方法将成为理解大脑障碍中神经可塑性如何表达的一个重要未来方向。
