The Computational, Cognitive and Clinical Neuroimaging Laboratory, Centre for Neuroscience, Division of Experimental Medicine and The Medical Research Council Clinical Sciences Centre, Imperial College London, London W120NN, United Kingdom.
J Neurosci. 2011 Sep 21;31(38):13442-51. doi: 10.1523/JNEUROSCI.1163-11.2011.
Traumatic brain injury (TBI) frequently produces impairments of attention in humans. These can result in a failure to maintain consistent goal-directed behavior. A predominantly right-lateralized frontoparietal network is often engaged during attentionally demanding tasks. However, lapses of attention have also been associated with increases in activation within the default mode network (DMN). Here, we study TBI patients with sustained attention impairment, defined on the basis of the consistency of their behavioral performance over time. We show that sustained attention impairments in patients are associated with an increase in DMN activation, particularly within the precuneus and posterior cingulate cortex. Furthermore, the interaction of the precuneus with the rest of the DMN at the start of the task, i.e., its functional connectivity, predicts which patients go on to show impairments of attention. Importantly, this predictive information is present before any behavioral evidence of sustained attention impairment, and the relationship is also found in a subgroup of patients without focal brain damage. TBI often results in diffuse axonal injury, which produces cognitive impairment by disconnecting nodes in distributed brain networks. Using diffusion tensor imaging, we demonstrate that structural disconnection within the DMN also correlates with the level of sustained attention. These results show that abnormalities in DMN function are a sensitive marker of impairments of attention and suggest that changes in connectivity within the DMN are central to the development of attentional impairment after TBI.
创伤性脑损伤（TBI）经常导致人类注意力受损。这些可能导致无法保持一致的目标导向行为。在注意力要求高的任务中，通常会涉及到主要位于右侧的额顶叶网络。然而，注意力的疏忽也与默认模式网络（DMN）内的激活增加有关。在这里，我们研究了注意力持续受损的 TBI 患者，这是根据他们随时间推移的行为表现的一致性来定义的。我们表明，患者的注意力持续受损与 DMN 激活的增加有关，特别是在楔前叶和后扣带回皮层内。此外，任务开始时楔前叶与 DMN 其余部分的相互作用，即其功能连接，预测哪些患者会出现注意力受损。重要的是，这种预测信息在出现任何持续注意力受损的行为证据之前就存在，并且在没有局灶性脑损伤的患者亚组中也发现了这种关系。TBI 通常会导致弥漫性轴索损伤，通过断开分布式大脑网络中的节点导致认知障碍。使用弥散张量成像，我们证明 DMN 内的结构连接中断也与持续注意力水平相关。这些结果表明，DMN 功能异常是注意力受损的敏感标志物，并表明 DMN 内连接性的变化是 TBI 后注意力损害发展的核心。
