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J Neurotrauma. 2018 Jan 15;35(2):267-277. doi: 10.1089/neu.2017.5117. Epub 2017 Dec 18.

Concussion Alters the Functional Brain Processes of Visual Attention and Working Memory.

Author information

1
1 Diagnostic Imaging, The Hospital for Sick Children , Toronto, Ontario, Canada .
2
2 Rotman Research Institute , Baycrest Centre, Toronto, Ontario, Canada .
3
3 Laboratoire de Cartographie Fonctionnelle du Cerveau, Erasme Hospital , ULB Bruxelles, Belgium .
4
4 Department of Surgery, Division of Neurosurgery, Sunnybrook Hospital, University of Toronto , Toronto, Ontario, Canada .
5
5 Division of Neurology, The Hospital for Sick Children , Toronto, Ontario, Canada .
6
6 Program in Neuroscience and Mental Health, SickKids Research Institute , Toronto, Ontario, Canada .
7
7 Department of Medical Imaging, Sunnybrook Hospital, University of Toronto , Toronto, Ontario, Canada .
8
8 Department of Psychology, Sunnybrook Hospital, University of Toronto , Toronto, Ontario, Canada .

Abstract

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.

KEYWORDS:

adult brain injury; cognitive function; electrophysiology; traumatic brain injury

PMID:
29020848
DOI:
10.1089/neu.2017.5117

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