The role of hippocampal theta oscillations in working memory impairment in multiple sclerosis

• Main Authors: Baijot, J. (Author), Costers, L. (Author), De Tiège, X. (Author), D'Haeseleer, M. (Author), D'hooghe, M.B (Author), Goldman, S. (Author), Laton, J. (Author), Nagels, G. (Author), Sjøgård, M. (Author), Van Schependom, J. (Author), Wens, V. (Author), Woolrich, M. (Author)
• Format: Article
• Language: English
• Published: John Wiley and Sons Inc 2021
• Subjects: adult; Adult; analgesic agent; anticonvulsive agent; antidepressant agent; Article; benzodiazepine derivative; cognitive defect; Cognitive Dysfunction; complication; controlled study; female; Female; hippocampus; Hippocampus; human; Humans; magnetoencephalography; Magnetoencephalography; major clinical study; male; Male; memory disorder; Memory, Short-Term; middle aged; Middle Aged; multiple sclerosis; Multiple Sclerosis; muscle relaxant agent; n-back; neurophysiology; oscillation; pathophysiology; physiology; post hoc analysis; priority journal; reaction time; right hippocampus; short term memory; theta; theta rhythm; Theta Rhythm; working memory
• Online Access: View Fulltext in Publisher

 Working memory (WM) problems are frequently present in people with multiple sclerosis (MS). Even though hippocampal damage has been repeatedly shown to play an important role, the underlying neurophysiological mechanisms remain unclear. This study aimed to investigate the neurophysiological underpinnings of WM impairment in MS using magnetoencephalography (MEG) data from a visual-verbal 2-back task. We analysed MEG recordings of 79 MS patients and 38 healthy subjects through event-related fields and theta (4–8 Hz) and alpha (8–13 Hz) oscillatory processes. Data was source reconstructed and parcellated based on previous findings in the healthy subject sample. MS patients showed a smaller maximum theta power increase in the right hippocampus between 0 and 400 ms than healthy subjects (p =.014). This theta power increase value correlated negatively with reaction time on the task in MS (r = −.32, p =.029). Evidence was provided that this relationship could not be explained by a ‘common cause’ confounding relationship with MS-related neuronal damage. This study provides the first neurophysiological evidence of the influence of hippocampal dysfunction on WM performance in MS. © 2020 The Authors. Human Brain Mapping published by Wiley Periodicals LLC.