DECODING NEURONAL ACTIVITY PATTERNS UNDERLYING VISUAL DISCRIMINATION DEFICITS AND HETEROGENEITY IN MULTIPLE SCLEROSIS PATIENTS

Previous studies have demonstrated impaired visual discrimination (VD) in patients with multiple sclerosis (MS), as assessed by the Farnsworth–Munsell 100 Hue Test, along with a higher interindividual variability in MS patients. The mechanisms underlying the overall performance deficit and the pronounced stratification of VD abilities in MS patients remain unclear.
We hypothesize that these differences are related to variating patterns of neuronal activation. To address this, we plan to investigate MS patients with good and poor VD performance using magnetoencephalography (MEG). As the previously used VD test is not compatible with MEG environments, we developed a digital VD paradigm for MEG recordings. The task comprises three difficulty levels, defined by different contrast ranges in blue or red color shades.
Here, we present the validation of this digital paradigm in a cohort of 22 healthy participants. Performance in the digital VD task correlated moderately with Farnsworth–Munsell scores, supporting its convergent validity. No significant differences were observed between participants completing the task for the first time and those with repeated exposure, indicating good test–retest stability. In a pilot MEG measurement in one healthy participant, we observed lower alpha-band power (8–14 Hz) in the visual cortex during difficult compared to easy task conditions.
Together, these findings support the validity of the digital VD paradigm for MEG studies and provide a foundation for future investigations into the neurophysiological basis of visual discrimination deficits and heterogeneity in MS.