Contributions
Abstract: EP1509
Type: Poster Sessions
Abstract Category: Pathology and pathogenesis of MS - MRI and PET
Introduction: Working memory problems are one of the main symptoms of cognitive impairment in multiple sclerosis (MS), with which about 30-70% of persons with MS (PwMS) are confronted (Amato et al., 2001). Previous event-related potential (ERP) studies have shown that P300 amplitudes decrease with increasing working memory load (Covey et al., 2017; Dong et al., 2015; Scharinger et al., 2017), and PwMS display lower P100 and P300 amplitudes than healthy controls (Covey et al., 2017). However, these studies have all been limited to sensor space and did not explore the role of functional reorganisation. This has been a well-documented phenomenon in MS (Pantano et al., 2006) and could cause variability in the locations of the neural generators of ERPs, which would lead to decreased ERP amplitudes.
Aims: In this study, we want to investigate the neurophysiology of working memory function in PwMS.
Objectives: We investigated the neural generators of working memory activity and related them to cognitive impairment in MS. In addition, we tried to confirm previous ERP findings and explored the role of functional reorganisation.
Methods: We performed an event-related field (ERF) analysis on magnetoencephalographic (MEG) data of a visual n-back task. In the n-back task, subjects are asked to press a button when they see an 'X' (0-back), the same letter as the previous one (1-back) or the same letter as two letters before (2-back) in a sequence of letters. The dataset consists of 79 MS patients and 38 healthy controls, who were matched on age, gender and education level. Data were source-reconstructed using a using a linearly constrained minimum variance beamformer.
Results: The MS group displayed increased reaction times for all three conditions (p < 1e-9) and lower accuracy rates on the 1- and 2-back trials (p < 0.01) compared to the healthy control group. Preliminary ERF results suggest decreases in M300 amplitudes in different regions for the three types of trials that seem to be a consequence of functional reorganisation in the MS group.
Conclusions: PwMS performed worse on the working memory task, and preliminary ERF results confirm previous findings on reduced M/P300 amplitudes in PwMS but suggest that this could be due to functional reorganisation as a consequence of MS-related structural damage.
Disclosure: Lars Costers is holder of a PhD grant awarded by the Flanders Research Foundation (FWO, www.fwo.be, grant no. 11B7218N). Jeroen Van Schependom is holder of a post- doctoral FWO grant (grant no. 12I1817N). Jorne Laton: nothing to disclose. Johan Baijot: nothing to disclose. Xavier De Tiège is Postdoctoral Clinical Master Specialist at the Fonds de la Recherche Scientifique (FRS-FNRS, Belgium). Serge Goldman: nothing to disclose. Marie-Beatrice D´hooghe has received travel grants, consultancy and speaker fees from Biogen, Teva, Novartis and Genzyme Sanofi. Miguel D´Haeseleer: nothing to disclose. Guy Nagels: holds a research chair by Merck and Novartis. None of these are likely to be relevant in the context of this manuscript.
Abstract: EP1509
Type: Poster Sessions
Abstract Category: Pathology and pathogenesis of MS - MRI and PET
Introduction: Working memory problems are one of the main symptoms of cognitive impairment in multiple sclerosis (MS), with which about 30-70% of persons with MS (PwMS) are confronted (Amato et al., 2001). Previous event-related potential (ERP) studies have shown that P300 amplitudes decrease with increasing working memory load (Covey et al., 2017; Dong et al., 2015; Scharinger et al., 2017), and PwMS display lower P100 and P300 amplitudes than healthy controls (Covey et al., 2017). However, these studies have all been limited to sensor space and did not explore the role of functional reorganisation. This has been a well-documented phenomenon in MS (Pantano et al., 2006) and could cause variability in the locations of the neural generators of ERPs, which would lead to decreased ERP amplitudes.
Aims: In this study, we want to investigate the neurophysiology of working memory function in PwMS.
Objectives: We investigated the neural generators of working memory activity and related them to cognitive impairment in MS. In addition, we tried to confirm previous ERP findings and explored the role of functional reorganisation.
Methods: We performed an event-related field (ERF) analysis on magnetoencephalographic (MEG) data of a visual n-back task. In the n-back task, subjects are asked to press a button when they see an 'X' (0-back), the same letter as the previous one (1-back) or the same letter as two letters before (2-back) in a sequence of letters. The dataset consists of 79 MS patients and 38 healthy controls, who were matched on age, gender and education level. Data were source-reconstructed using a using a linearly constrained minimum variance beamformer.
Results: The MS group displayed increased reaction times for all three conditions (p < 1e-9) and lower accuracy rates on the 1- and 2-back trials (p < 0.01) compared to the healthy control group. Preliminary ERF results suggest decreases in M300 amplitudes in different regions for the three types of trials that seem to be a consequence of functional reorganisation in the MS group.
Conclusions: PwMS performed worse on the working memory task, and preliminary ERF results confirm previous findings on reduced M/P300 amplitudes in PwMS but suggest that this could be due to functional reorganisation as a consequence of MS-related structural damage.
Disclosure: Lars Costers is holder of a PhD grant awarded by the Flanders Research Foundation (FWO, www.fwo.be, grant no. 11B7218N). Jeroen Van Schependom is holder of a post- doctoral FWO grant (grant no. 12I1817N). Jorne Laton: nothing to disclose. Johan Baijot: nothing to disclose. Xavier De Tiège is Postdoctoral Clinical Master Specialist at the Fonds de la Recherche Scientifique (FRS-FNRS, Belgium). Serge Goldman: nothing to disclose. Marie-Beatrice D´hooghe has received travel grants, consultancy and speaker fees from Biogen, Teva, Novartis and Genzyme Sanofi. Miguel D´Haeseleer: nothing to disclose. Guy Nagels: holds a research chair by Merck and Novartis. None of these are likely to be relevant in the context of this manuscript.