Mouth magnetoencephalography: A unique perspective on the human hippocampus
Tim M. Tierney,
Andrew Levy,
Daniel N. Barry,
Sofie S. Meyer,
Yoshihito Shigihara,
Matt Everatt,
Stephanie Mellor,
Jose David Lopez,
Sven Bestmann,
Niall Holmes,
Gillian Roberts,
Ryan M Hill,
Elena Boto,
James Leggett,
Vishal Shah,
Matthew J. Brookes,
Richard Bowtell,
Eleanor A. Maguire,
Gareth R. Barnes
Affiliations
Tim M. Tierney
Wellcome Centre for Human Neuroimaging, UCL Queen Square Institute of Neurology, University College London, 12 Queen Square, London WC1N 3AR, UK; Corresponding author.
Andrew Levy
Wellcome Centre for Human Neuroimaging, UCL Queen Square Institute of Neurology, University College London, 12 Queen Square, London WC1N 3AR, UK
Daniel N. Barry
Wellcome Centre for Human Neuroimaging, UCL Queen Square Institute of Neurology, University College London, 12 Queen Square, London WC1N 3AR, UK
Sofie S. Meyer
Wellcome Centre for Human Neuroimaging, UCL Queen Square Institute of Neurology, University College London, 12 Queen Square, London WC1N 3AR, UK; Institute of Cognitive Neuroscience, University College London, 17-19 Queen Square, London WC1N 3AZ, UK
Yoshihito Shigihara
Hokuto Hospital MEG Lab, Hokkaido, Japan
Matt Everatt
S4S (UK) Limited & Smilelign Ltd, 151 Rutland Road, Sheffield S3 9PT, UK
Stephanie Mellor
Wellcome Centre for Human Neuroimaging, UCL Queen Square Institute of Neurology, University College London, 12 Queen Square, London WC1N 3AR, UK
Jose David Lopez
Engineering Faculty, Universidad de Antioquia UDEA, calle 70 No 52-21, Medellín, Colombia
Sven Bestmann
Wellcome Centre for Human Neuroimaging, UCL Queen Square Institute of Neurology, University College London, 12 Queen Square, London WC1N 3AR, UK
Niall Holmes
Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, University Park, Nottingham NG7 2RD, UK
Gillian Roberts
Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, University Park, Nottingham NG7 2RD, UK
Ryan M Hill
Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, University Park, Nottingham NG7 2RD, UK
Elena Boto
Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, University Park, Nottingham NG7 2RD, UK
James Leggett
Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, University Park, Nottingham NG7 2RD, UK
Vishal Shah
QuSpin Inc., 2011 Cherry Street, Unit 112, Louisville, CO 80027, USA
Matthew J. Brookes
Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, University Park, Nottingham NG7 2RD, UK
Richard Bowtell
Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, University Park, Nottingham NG7 2RD, UK
Eleanor A. Maguire
Wellcome Centre for Human Neuroimaging, UCL Queen Square Institute of Neurology, University College London, 12 Queen Square, London WC1N 3AR, UK
Gareth R. Barnes
Wellcome Centre for Human Neuroimaging, UCL Queen Square Institute of Neurology, University College London, 12 Queen Square, London WC1N 3AR, UK
Traditional magnetoencephalographic (MEG) brain imaging scanners consist of a rigid sensor array surrounding the head; this means that they are maximally sensitive to superficial brain structures. New technology based on optical pumping means that we can now consider more flexible and creative sensor placement. Here we explored the magnetic fields generated by a model of the human hippocampus not only across scalp but also at the roof of the mouth. We found that simulated hippocampal sources gave rise to dipolar field patterns with one scalp surface field extremum at the temporal lobe and a corresponding maximum or minimum at the roof of the mouth. We then constructed a fitted dental mould to accommodate an Optically Pumped Magnetometer (OPM). We collected data using a previously validated hippocampal-dependant task to test the empirical utility of a mouth-based sensor, with an accompanying array of left and right temporal lobe OPMs. We found that the mouth sensor showed the greatest task-related theta power change. We found that this sensor had a mild effect on the reconstructed power in the hippocampus (~10% change) but that coherence images between the mouth sensor and reconstructed source images showed a global maximum in the right hippocampus. We conclude that augmenting a scalp-based MEG array with sensors in the mouth shows unique promise for both basic scientists and clinicians interested in interrogating the hippocampus.
