A Novel, Robust, and Portable Platform for Magnetoencephalography using Optically Pumped Magnetometers

Schofield, H.; Hill, R. M.; Feys, O. M.; Holmes, N.; Osborne, J.; Doyle, C.; Bobela, D.; Corvilain, P.; Wens, V.; Rier, L.; Bowtell, R.; Ferez, M.; Mullinger, K. J.; Coleman, S.; Rhodes, N.; Rea, M.; Tanner, Z.; Boto, E.; De Tiege, X.; Shah, V.; Brookes, M. J.

doi:10.1101/2024.03.06.583313

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bioRxiv · 10.1101/2024.03.06.583313

A Novel, Robust, and Portable Platform for Magnetoencephalography using Optically Pumped Magnetometers

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Abstract

Magnetoencephalography (MEG) measures brain function via assessment of magnetic fields generated by neural currents. Conventional MEG uses superconducting sensors, which place significant limitations on performance, practicality, and deployment; however, the field has been revolutionised in recent years by the introduction of optically-pumped-magnetometers (OPMs). OPMs enable measurement of the MEG signal without cryogenics, and consequently the conception of OPM-MEG systems which ostensibly allow increased sensitivity and resolution, lifespan compliance, free subject movement, and lower cost. However, OPM-MEG remains in its infancy with limitations on both sensor and system design. Here, we report a new OPM-MEG design with miniaturised and integrated electronic control, a high level of portability, and improved sensor dynamic range (arguably the biggest limitation of existing instrumentation). We show that this system produces equivalent measures when compared to an established instrument; specifically, when measuring task-induced beta-band, gamma-band and evoked neuro-electrical responses, source localisations from the two systems were highly comparable and temporal correlation was >0.7 at the individual level and >0.9 for groups. Using an electromagnetic phantom, we demonstrate improved dynamic range by running the system in background fields up to 8 nT. We show that the system is effective in gathering data during free movement (including a sitting-to-standing paradigm) and that it is compatible with simultaneous electroencephalography (EEG - the clinical standard). Finally, we demonstrate portability by moving the system between two laboratories. Overall, our new system is shown to be a significant step forward for OPM-MEG technology and offers an attractive platform for next generation functional medical imaging.

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Schofield, H., Hill, R. M., Feys, O. M., Holmes, N., Osborne, J., Doyle, C., Bobela, D., Corvilain, P., Wens, V., Rier, L., Bowtell, R., Ferez, M., Mullinger, K. J., Coleman, S., Rhodes, N., Rea, M., Tanner, Z., Boto, E., De Tiege, X., Shah, V., Brookes, M. J.. 2024-03-11. A Novel, Robust, and Portable Platform for Magnetoencephalography using Optically Pumped Magnetometers. https://doi.org/10.1101/2024.03.06.583313

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