Structural correlates of atypical visual and motor cortical oscillations in pediatric‐onset multiple sclerosis

Abstract

We have previously demonstrated that pediatric‐onset multiple sclerosis (POMS) negatively impacts the visual pathway as well as motor processing speed. Relationships between MS‐related diffuse structural damage of gray and white matter (WM) tissue and cortical responses to visual and motor stimuli remain poorly understood. We used magnetoencephalography in 14 POMS patients and 15 age‐ and sex‐matched healthy controls to assess visual gamma (30–80 Hz), motor gamma (60–90 Hz), and motor beta (15–30 Hz) cortical oscillatory responses to a visual‐motor task. Then, 3T MRI was used to: (a) calculate fractional anisotropy (FA) of the posterior visual and corticospinal motor WM pathways and (b) quantify volume and thickness of the cuneus and primary motor cortex. Visual gamma band power was reduced in POMS and was associated with reduced FA of the optic radiations but not with loss of cuneus volume or thickness. Activity in the primary motor cortex, as measured by postmovement beta rebound amplitude associated with peak latency, was decreased in POMS, although this reduction was not predicted by structural metrics. Our findings implicate loss of WM integrity as a contributor to reduced electrical responses in the visual cortex in POMS. Future work in larger cohorts will inform on the cognitive implications of this finding in terms of visual processing function and will determine whether the progressive loss of brain volume known to occur in POMS ultimately contributes to both progressive dysfunction in such tasks as well as progressive reduction in cortical electrical responses in the visual cortex.

The utility of Magnetoencephalography in multiple sclerosis – A systematic review

“…3 ). In Arpin et al (2017) PMBR power was diminished in patients versus controls, while the visuo-motor task showed reduction in visual gamma and a reduction in PMBR amplitude associated with peak latency in patients vs controls ( Waldman et al, 2020 ). Barrett et al (2017) demonstrated a reduction in visual gamma power on stimulation, and a lag in PMBR in patients vs controls.…”

“…Three studies looked at motor events ( Arpin et al, 2017b , Barratt et al, 2017 , Waldman et al, 2020 ) whilst three studies looked at visual responses ( Barratt et al, 2017 , Stickland et al, 2019 , Waldman et al, 2020 ). Since Barrett et al and Waldman et al undertook visuomotor tasks, these are presented together.…”

“…Since Barrett et al and Waldman et al undertook visuomotor tasks, these are presented together. Arpin et al (2017) and Waldman et al (2020) examined Event Related Beta Desynchronisation (ERBD) and Post Movement Beta Rebound (PMBR) (see Fig. 3 ).…”

“…3 Waldman et al, 2020 undertook a visuomotor task in patients with Paediatric Onset Multiple Sclerosis (POMS) vs controls: Visual Time Frequency Response and Visual amplitude plots are shown. a and b show group-averaged time–frequency for controls and paediatric onset multiple sclerosis (POMS) with reduction in visual gamma band in both hemispheres; c and d show the visual gamma power (30–80 Hz) compared between POMS (red) and controls (black) in right (c) and left (d) hemispheres (Adapted from ( Waldman et al, 2020 )). (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)…”

Regional Difference in Myelination in Monocarboxylate Transporter 8 Deficiency: Case Reports and Literature Review of Cases in Japan

“…These facts indicate that MRI signal of myelination do not necessarily imply histopathologically complete myelination. Diffusion tensor imaging is reportedly useful in the evaluation of demyelination disease (34) or leukodystrophy (35). More advanced methods for assessment of myelination such as diffusion tensor imaging may help clarify minute abnormalities in myelination in patients with MCT8 deficiency.…”