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Original Research ARTICLE Provisionally accepted The full-text will be published soon. Notify me

Front. Neurol. | doi: 10.3389/fneur.2018.00494

Visual working memory encoding and recognition in good outcome aneurysmal subarachnoid patients.

  • 1Department of Surgery, Division of Neurosurgery, Sunnybrook Hospital, University of Toronto, Canada
  • 2Department of Diagnostic Imaging, Hospital for Sick Children, Canada
  • 3Sick Kids Research Institute, Canada
  • 4Canadian Partnership for Stroke Recovery, Sunnybrook Research Institute (SRI), Canada
  • 5Division of Neurology, Hospital for Sick Children, Canada

Objectives: Aneurysmal subarachnoid hemorrhage (aSAH) accounts for less than 5% of strokes but is associated with significant morbidity and mortality. Amongst survivors, neurocognitive complaints are common, often despite normal imaging. We used magnetoencephalography (MEG) to investigate neurophysiological function during a visual working memory task in aSAH survivors with good recovery and normal structural imaging.
Methods: Patients with aSAH treated with coiling and exhibiting good outcome measured by Glasgow Outcome Scale (GOS) and without related parenchymal structural lesions in post-treatment MRI, were recruited and compared to age- and sex-matched controls. All participants underwent intelligence and cognitive screening, structural MRI, and MEG testing in conjunction with a 1­back visual working memory task. Sensor-level global field power and virtual electrode source analysis of neuronal activity and connectivity in aSAH was assessed.
Results: Thirteen patients and 13 matched controls were enrolled (age: 56 ± 11 years, 19 female). The 1-back task was completed with similar accuracy despite a trend for a longer reaction time in aSAH patients (p=0.054). During encoding and recognition phases, aSAH patients showed significantly increased neuronal activation and hyperconnectivity in periventricular areas, specifically the anterior and posterior cingulate gyri.
Conclusions: Increased posterior and anterior cingulate gyri neuronal activity is demonstrated in aSAH patients during visual working memory tasks, in the absence of structural lesions. These areas work mainly as a hub to “organize” memory storage and retrieval. Increased activity in these areas might be compensatory due to injury and consequently loss of neuronal response in connected areas in the working memory networks.

Keywords: Aneurysm, encoding, Magnetoencephalography, recognition memory task, Subarachnoid Hemorrhage, working memory

Received: 21 Feb 2018; Accepted: 06 Jun 2018.

Edited by:

Fabiana Novellino, Consiglio Nazionale Delle Ricerche (CNR), Italy

Reviewed by:

Jeanne Teitelbaum, McGill University, Canada
Nicola Amoroso, Università degli studi di Bari Aldo Moro, Italy  

Copyright: © 2018 Da Costa, Shah-Basak, Dunkley, Robertson and Pang. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Dr. Leo Da Costa, University of Toronto, Department of Surgery, Division of Neurosurgery, Sunnybrook Hospital, Toronto, Canada, leo.dacosta@sunnybrook.ca