1 Diagnostic Imaging, The Hospital for Sick Children , Toronto, Ontario, Canada .
2 Rotman Research Institute , Baycrest Centre, Toronto, Ontario, Canada .
J Neurotrauma. 2018 Jan 15;35(2):267-277. doi: 10.1089/neu.2017.5117. Epub 2017 Dec 18.
Millions of North Americans sustain a concussion or a mild traumatic brain injury annually, and are at risk of cognitive, emotional, and physical sequelae. Although functional MRI (fMRI) studies have provided an initial framework for examining functional deficits induced by concussion, particularly working memory and attention, the temporal dynamics underlying these deficits are not well understood. We used magnetoencephalography (MEG), a modality with millisecond temporal resolution, in conjunction with a 1-back visual working memory (VWM) paradigm using scenes from everyday life to characterize spatiotemporal functional differences at specific VWM stages, in adults had had or had not had a recent concussion. MEG source-level differences between groups were determined by whole-brain analyses during encoding and recognition phases. Despite comparable behavioral performance, abnormal hypo- and hyperactivation patterns were found in brain areas involving frontoparietal, ventral occipitotemporal, temporal, and subcortical areas in concussed patients. These patterns and their timing varied as a function of VWM stagewise processing, linked to early attentional control, visuoperceptual scene processing, and VWM maintenance and retrieval processes. Parietal hypoactivation, starting at 60 ms during encoding, was correlated with symptom severity, possibly linked to impaired top-down attentional processing. Hyperactivation in the scene-selective occipitotemporal areas, the medial temporal complex, specifically the right hippocampus and orbitofrontal areas during encoding and/or recognition, lead us to posit inefficient but compensatory visuoperceptual, relational, and retrieval processing. Although injuries sustained after the concussion were considered "mild," these data suggest that they can have prolonged effects on early attentional and VWM processes.
数以百万计的北美成年人每年都会遭受脑震荡或轻度创伤性脑损伤，并且存在认知、情感和身体后遗症的风险。尽管功能磁共振成像（fMRI）研究为检查脑震荡引起的功能缺陷，特别是工作记忆和注意力，提供了初步框架，但这些缺陷的时间动态尚不清楚。我们使用了脑磁图（MEG），这是一种具有毫秒时间分辨率的模态，结合日常生活场景的 1 背视觉工作记忆（VWM）范式，以特征化特定 VWM 阶段的时空功能差异，在成年人中，他们是否有近期的脑震荡。通过在编码和识别阶段进行全脑分析，确定了组间 MEG 源水平差异。尽管行为表现相当，但在涉及额顶叶、腹侧枕颞叶、颞叶和皮质下区域的脑区中，发现了异常的低激活和高激活模式，这些模式及其时间变化与 VWM 分阶段处理有关，与早期注意力控制、视觉感知场景处理以及 VWM 保持和检索过程有关。在编码期间，从 60 毫秒开始的顶叶低激活与症状严重程度相关，可能与自上而下的注意力处理受损有关。在编码和/或识别期间，场景选择性枕颞叶区域、内侧颞叶复合体、特别是右侧海马体和眶额区域的过度激活，使我们假设存在低效但补偿性的视觉感知、关系和检索处理。尽管脑震荡后的损伤被认为是“轻度”的，但这些数据表明，它们可能对早期注意力和 VWM 过程产生长期影响。
