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bioRxiv · 10.1101/2021.05.26.445793

Using OPMs to measure neural activity in standing, mobile participants

Seymour, R. A.·Alexander, N.·Mellor, S. J.·O'Neill, G. C.·Tierney, T. M.·Barnes, G. R.·Maguire, E. A.
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Abstract

Optically pumped magnetometer-based magnetoencephalography (OP-MEG) can be used to measure neuromagnetic fields while participants move in a magnetically shielded room. Head movements in previous OP-MEG studies have been up to 20 cm translation and [~]30{degrees} rotation in a sitting position. While this represents a step-change over stationary MEG systems, naturalistic head movement is likely to exceed these limits, particularly when participants are standing up. In this proof-of-concept study, we sought to push the movement limits of OP-MEG even further. Using a 90 channel (45-sensor) whole-head OP-MEG system and concurrent motion capture, we recorded auditory evoked fields while participants were: (i) sitting still, (ii) standing up and still, and (iii) standing up and making large natural head movements continuously throughout the recording - maximum translation 120 cm, maximum rotation 198{degrees}. Following pre-processing, movement artefacts were substantially reduced but not eliminated. However, upon utilisation of a beamformer, the M100 event-related field localised to primary auditory regions. Furthermore, the event-related fields from auditory cortex were remarkably consistent across the three conditions. These results suggest that a wide range of movement is possible with current OP-MEG systems. This in turn underscores the exciting potential of OP-MEG for recording neural activity during naturalistic paradigms that involve movement (e.g. navigation), and for scanning populations who are difficult to study with stationary MEG (e.g. young children).

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Seymour, R. A., Alexander, N., Mellor, S. J., O'Neill, G. C., Tierney, T. M., Barnes, G. R., Maguire, E. A.. 2021-05-27. Using OPMs to measure neural activity in standing, mobile participants. https://doi.org/10.1101/2021.05.26.445793

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