title: A new generation of magnetoencephalography: Room temperature measurements using optically-pumped magnetometers.
abstract: Advances in the field of quantum sensing mean that magnetic field sensors, operating at room temperature, are now able to achieve sensitivity similar to that of cryogenically cooled devices (SQUIDs). This means that room temperature magnetoencephalography (MEG), with a greatly increased flexibility of sensor placement can now be considered. Further, these new sensors can be placed directly on the scalp surface giving, theoretically, a large increase in the magnitude of the measured signal. Here, we present recordings made using a single optically-pumped magnetometer (OPM) in combination with a 3D-printed head-cast designed to accurately locate and orient the sensor relative to brain anatomy. Since our OPM is configured as a magnetometer it is highly sensitive to environmental interference. However, we show that this problem can be ameliorated via the use of simultaneous reference sensor recordings. Using median nerve stimulation, we show that the OPM can detect both evoked (phase-locked) and induced (non-phase-locked oscillatory) changes when placed over sensory cortex, with signals ~4 times larger than equivalent SQUID measurements. Using source modelling, we show that our system allows localisation of the evoked response to somatosensory cortex. Further, source-space modelling shows that, with 13 sequential OPM measurements, source-space signal-to-noise ratio (SNR) is comparable to that from a 271-channel SQUID system. Our results highlight the opportunity presented by OPMs to generate uncooled, potentially low-cost, high SNR MEG systems.
authors.affiliation: Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom.
authors.forename: Elena
authors.initials: E
authors.lastname: Boto
authors.affiliation: Wellcome Trust Centre for Neuroimaging, Institute of Neurology, University College London, 12 Queen Square, London WC1N 3BG, United Kingdom.
authors.forename: Sofie S
authors.initials: SS
authors.lastname: Meyer
authors.affiliation: QuSpin Inc., 2011 Cherry Street, Unit 112, Louisville, CO 80027, USA.
authors.forename: Vishal
authors.initials: V
authors.lastname: Shah
authors.affiliation: QuSpin Inc., 2011 Cherry Street, Unit 112, Louisville, CO 80027, USA.
authors.forename: Orang
authors.initials: O
authors.lastname: Alem
authors.affiliation: QuSpin Inc., 2011 Cherry Street, Unit 112, Louisville, CO 80027, USA.
authors.forename: Svenja
authors.initials: S
authors.lastname: Knappe
authors.affiliation: Midlands Ultracold Atom Research Centre, School of Physics and Astronomy, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom.
authors.forename: Peter
authors.initials: P
authors.lastname: Kruger
authors.affiliation: Midlands Ultracold Atom Research Centre, School of Physics and Astronomy, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom.
authors.forename: T Mark
authors.initials: TM
authors.lastname: Fromhold
authors.affiliation: Chalk Studios Ltd., 14 Windsor Street, London N1 8QG, United Kingdom.
authors.forename: Mark
authors.initials: M
authors.lastname: Lim
authors.affiliation: Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom.
authors.forename: Paul M
authors.initials: PM
authors.lastname: Glover
authors.affiliation: Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom.
authors.forename: Peter G
authors.initials: PG
authors.lastname: Morris
authors.affiliation: Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom.
authors.forename: Richard
authors.initials: R
authors.lastname: Bowtell
authors.affiliation: Wellcome Trust Centre for Neuroimaging, Institute of Neurology, University College London, 12 Queen Square, London WC1N 3BG, United Kingdom.
authors.forename: Gareth R
authors.initials: GR
authors.lastname: Barnes
authors.affiliation: Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom. Electronic address: matthew.brookes@nottingham.ac.uk.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Brookes
mesh_terms: D001921:Brain / Q000502:physiology*; D001931:Brain Mapping / Q000379:methods*; D005073:Evoked Potentials, Somatosensory / Q000502:physiology; D006801:Humans; D015225:Magnetoencephalography / Q000295:instrumentation* / Q000379:methods*; D059629:Signal-To-Noise Ratio; D013696:Temperature