Stimulus-related modulation in the 1/f spectral slope suggests an impaired inhibition of irrelevant information in people with multiple sclerosis

• Published in: bioRxiv
• Main Authors: Akbarian, Fahimeh, Rossi, Chiara, Costers, Lars, D'hooghe, Marie B, D'haeseleer, Miguel, Nagels, Guy, Jeroen Van Schependom
• Format: Paper
• Language: English
• Published: Cold Spring Harbor Cold Spring Harbor Laboratory Press 30.12.2023; Cold Spring Harbor Laboratory
• Edition: 1.1
• Subjects: Cognitive ability; Information processing; Magnetoencephalography; Memory; Multiple sclerosis; Neurodegenerative diseases; Neuroscience; Reaction time task; Short term memory; Spatial memory; Synaptic transmission; excitation/inhibition balance; n-back task; working memory; multiple sclerosis; aperiodic; 1/f exponent; magnetoencephalography
• ISSN: 2692-8205; 2692-8205
• DOI: 10.1101/2023.12.28.573572

Background: Multiple sclerosis (MS) is an inflammatory and neurodegenerative disease characterized by neuronal and synaptic loss, resulting in an imbalance of excitatory and inhibitory synaptic transmission. MS leads to cognitive impairment such as reduced information processing speed and impaired working memory (WM). Recent studies have suggested that the 1/f slope of EEG/MEG power spectra can be associated with the excitation/inhibition (E/I) balance. A normal E/I balance is crucial for normal information processing and working memory. Methods: We analyzed magnetoencephalographic (MEG) recordings of 38 healthy control subjects and 79 people with multiple sclerosis (pwMS) while performing an n-back working task. We computed and compared the steepness of the 1/f spectral slope through the FOOOF algorithm in the time windows [-1 0] and [0 1] s peristimulus time for both target and distractor stimulus for each brain parcel and for different working memory loads (0-back, 1-back, 2-back). Results: The spectral slope was significantly steeper after the stimulus onset and was correlated with reaction time. We also observed a steeper 1/f slope after distractor stimuli in healthy subjects compared to pwMS. Finally, we observed significant correlations between the 1/f spectral slope modulation and visuospatial working memory functioning in both healthy subjects and pwMS. Conclusion. Our findings are consistent with an increased inhibition following stimulus onset. In pwMS, this increase is reduced, suggesting dysfunctional inhibition of irrelevant information. Finally, this impaired modulation is significantly associated with a pencil-paper test of visuospatial working memory.Competing Interest StatementThe authors have declared no competing interest.