Using OPMs to measure neural activity in standing, mobile participants

Seymour, Robert A.; Alexander, Nicholas A; Mellor, Stephanie; O'Neill, George; Tierney, Tim M.; Barnes, Gareth R.; Maguire, Eleanor A.

doi:10.1016/j.neuroimage.2021.118604

Cited by 57 publications

(48 citation statements)

References 60 publications

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“…Yet, OPM technology is currently under development; therefore, the high cost and the requirement of magnetic shielding still limit its use to research context. However, in view of the promising advancement of wearable OPM systems for MEG application (Boto et al, 2019;Roberts et al, 2019;Boto et al, 2021;Seymour et al, 2021), and the progress in development of OPM-optimized magnetic shielding solutions (Holmes et al, 2018;Iivanainen et al, 2019;Borna et al, 2020;Zhang et al, 2020), it is foreseeable a broader diffusion of the technology in the future with a consequential decrease of the costs. This would paved the way toward the development of wearable OPM-MMG systems (Zuo et al, 2020), for the measurement and assessment of muscle activity for research and diagnostic purposes.…”

Section: Discussionmentioning

confidence: 99%

Muscle Fatigue Revisited – Insights From Optically Pumped Magnetometers

et al. 2021

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So far, surface electromyography (sEMG) has been the method of choice to detect and evaluate muscle fatigue. However, recent advancements in non-cryogenic quantum sensors, such as optically pumped magnetometers (OPMs), enable interesting possibilities to flexibly record biomagnetic signals. Yet, a magnetomyographic investigation of muscular fatigue is still missing. Here, we simultaneously used sEMG (4 surface electrode) and OPM-based magnetomyography (OPM-MMG, 4 sensors) to detect muscle fatigue during a 3 × 1-min isometric contractions of the left rectus femoris muscle in 7 healthy participants. Both signals exhibited the characteristic spectral compression distinctive for muscle fatigue. OPM-MMG and sEMG slope values, used to quantify the spectral compression of the signals, were positively correlated, displaying similarity between the techniques. Additionally, the analysis of the different components of the magnetic field vector enabled speculations regarding the propagation of the muscle action potentials (MAPs). Altogether these results show the feasibility of the magnetomyographic approach with OPMs and propose a potential alternative to sEMG for the study of muscle fatigue.

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Section: Discussionmentioning

confidence: 99%

Muscle Fatigue Revisited – Insights From Optically Pumped Magnetometers

et al. 2021

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“…Due to the multiple stages in motor processing before the spinal cord, activity may be more temporally dispersed, potentially leading to weaker signals. Additionally, movement artefacts will create challenges in data processing, however, previous OP-MEG work has identified analysis pipelines to overcome this 34,54 . Moreover, changes in power may provide greater insight into motor processing at the spinal level, which along with OP-MEG recordings could illuminate cortico-spinal interactions 55 .…”

Section: Discussionmentioning

confidence: 99%

Concurrent spinal and brain imaging with optically pumped magnetometers

Mardell

O'Neill

Tierney

et al. 2022

Preprint

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The spinal cord and its interactions with the brain are fundamental for movement control and somatosensation. However, brain and spinal cord electrophysiology in humans have largely been treated as distinct enterprises, in part due to the relative inaccessibility of the spinal cord. Consequently, there is a dearth of knowledge on human spinal electrophysiology, including the multiple pathologies of the central nervous system that affect the spinal cord as well as the brain. Here we exploit recent advances in the development of wearable optically pumped magnetometers (OPMs) which can be flexibly arranged to provide coverage of both the spinal cord and the brain concurrently in unconstrained environments. Our system for magnetospinoencephalography (MSEG) measures both spinal and cortical signals simultaneously by employing a custom-made spinal scanning cast. We evidence the utility of such a system by recording simultaneous spinal and cortical evoked responses to median nerve stimulation, demonstrating the novel ability for concurrent non-invasive millisecond imaging of brain and spinal cord.

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“…Immersive virtual reality environments could also be used in combination with new wearable MEG systems. 103 , 104 …”

Section: Discussionmentioning

confidence: 99%

Cortical oscillatory dysrhythmias in visual snow syndrome: a magnetoencephalography study

Hepschke

Seymour

et al. 2021

Brain Communications

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Visual Snow refers to the persistent visual experience of static in the whole visual field of both eyes. It is often reported by patients with migraine and co-occurs with conditions like tinnitus and tremor. The underlying pathophysiology of the condition is poorly understood. Previously we hypothesised, that visual snow syndrome may be characterised by disruptions to rhythmical activity within the visual system. To test this, data from 18 patients diagnosed with visual snow syndrome, and 16 matched controls, were acquired using magnetoencephalography. Participants were presented with visual grating stimuli, known to elicit decreases in alpha-band (8-13Hz) power and increases in gamma-band power (40-70Hz). Data were mapped to source-space using a beamformer. Across both groups, decreased alpha power and increased gamma power localised to early visual cortex. Data from the primary visual cortex were compared between groups. No differences were found in either alpha or gamma peak frequency or the magnitude of alpha power, p>0.05. However, compared with controls, our visual snow syndrome cohort displayed significantly increased primary visual cortex gamma power, p=0.035. This new electromagnetic finding concurs with previous functional MRI and PET findings suggesting that in visual snow syndrome, the visual cortex is hyper-excitable. The coupling of alpha-phase to gamma amplitude within the primary visual cortex was also quantified. Compared with controls, the visual snow syndrome group had significantly reduced alpha-gamma phase-amplitude coupling, p<0.05, indicating a potential excitation-inhibition imbalance in visual snow syndrome, as well as a potential disruption to top-down “noise-cancellation” mechanisms. Overall, these results suggest that rhythmical brain activity in primary visual cortex is both hyperexcitable and disorganised in visual snow syndrome, consistent with this being a condition of thalamocortical dysrhythmia.

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Using OPMs to measure neural activity in standing, mobile participants

Cited by 57 publications

References 60 publications

Muscle Fatigue Revisited – Insights From Optically Pumped Magnetometers

Muscle Fatigue Revisited – Insights From Optically Pumped Magnetometers

Concurrent spinal and brain imaging with optically pumped magnetometers

Cortical oscillatory dysrhythmias in visual snow syndrome: a magnetoencephalography study

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