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Measuring MEG closer to the brain: Performance of on-scalp sensor arrays
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Abstract
Optically-pumped magnetometers (OPMs) have recently reached sensitivity levels required for magnetoencephalography (MEG). OPMs do not need cryogenics and can thus be placed within millimetres from the scalp into an array that adapts to the individual head size and shape, thereby reducing the distance from cortical sources to the sensors. Here, we quantified the improvement in recording MEG with hypothetical on-scalp OPM arrays compared to a 306-channel state-of-the-art SQUID array (102 magnetometers and 204 planar gradiometers). We simulated OPM arrays that measured either normal (nOPM; 102 sensors), tangential (tOPM; 204 sensors), or all components (aOPM; 306 sensors) of the magnetic field. We built forward models based on magnetic resonance images of 10 adult heads; we employed a three-compartment boundary element model and distributed current dipoles evenly across the cortical mantle. Compared to the SQUID magnetometers, nOPM and tOPM yielded 7.5 and 5.3 times higher signal power, while the correlations between the field patterns of source dipoles were reduced by factors of 2.8 and 3.6, respectively. Values of the field-pattern correlations were similar across nOPM, tOPM and SQUID gradiometers. Volume currents reduced the signals of primary currents on average by 10%, 72% and 15% in nOPM, tOPM and SQUID magnetometers, respectively. The information capacities of the OPM arrays were clearly higher than that of the SQUID array. The dipole-localization accuracies of the arrays were similar while the minimum-norm-based point-spread functions were on average 2.4 and 2.5 times more spread for the SQUID array compared to nOPM and tOPM arrays, respectively.
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“Increased proximity to the scalp can improve sensitivity and spatial resolution beyond that which is achieved using a cryogenic MEG [26,27].”
From Naturalistic Hyperscanning with Wearable Magnetoencephalography (2023) · cites this paper as [27]
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Cited by
Sorted by citations
Brookes, M. J., Leggett, J., Rea, M., Hill, R. M., Holmes, N., Boto, E., & Bowtell, R. W. (2022) · Trends in Neurosciences · doi:10.1016/j.tins.2022.05.008 · Cited by 438
“Simulations [12,13] show that this effect provides a four- to fivefold signal enhancement in many cortical areas.”
BackgroundOptically pumped magnetometers: from quantum origins to multi-channel magnetoencephalography
Tierney, T. M., Holmes, N., Mellor, S., López, J. D., Roberts, G., Hill, R. M., Boto, E., Leggett, J., Shah, V., Brookes, M. J., et al. (2019) · NeuroImage · doi:10.1016/j.neuroimage.2019.05.063 · Cited by 400
“…advances in sensors, additional neuroscientific motivation for OPMs came from simulation studies examining issues such as improvements in SNR, spatial resolution and the requirements necessary for accurate source reconstruction (Boto et al., 2016a; Iivanainen et al., 2017a; Zetter et al., 2017).”
BackgroundMulti-Channel Whole-Head OPM-MEG: Helmet Design and a Comparison with a Conventional System
Hill, R. M., Boto, E., Rea, M., Holmes, N., Leggett, J., Coles, L. A., Papastavrou, M., Everton, S. K., Hunt, B. A. E., Sims, D., et al. (2020) · NeuroImage · doi:10.1016/j.neuroimage.2020.116995 · Cited by 285
Ultrasensitive Magnetic Field Sensors for Biomedical Applications
Murzin, D., Mapps, D. J., Levada, K., Belyaev, V., Omelyanchik, A., Panina, L., & Rodionova, V. (2020) · Sensors · doi:10.3390/s20061569 · Cited by 277
On-scalp MEG system utilizing an actively shielded array of optically-pumped magnetometers
Iivanainen, J., Zetter, R., Grön, M., Hakkarainen, K., & Parkkonen, L. (2019) · NeuroImage · doi:10.1016/j.neuroimage.2019.03.022 · Cited by 269
Self-citationHolmes, N., Leggett, J., Boto, E., Roberts, G., Hill, R. M., Tierney, T. M., Shah, V., Barnes, G. R., Brookes, M. J., & Bowtell, R. (2018) · NeuroImage · doi:10.1016/j.neuroimage.2018.07.028 · Cited by 250
“Simulation studies (Boto et al., 2016; Iivanainen et al., 2017) have demonstrated the gains in performance which could be achieved using OPM-based MEG systems.”
MethodBoto, E., Shah, V., Hill, R. M., Rhodes, N., Osborne, J., Doyle, C., Holmes, N., Rea, M., Leggett, J., Bowtell, R. W., et al. (2022) · NeuroImage · doi:10.1016/j.neuroimage.2022.119027 · Cited by 195
“3) Triaxial sensors provide three times more measurements; tangential fields are known to be weaker than radial fields (Iivanainen et al., 2017) and so this does not”
BackgroundA 20-channel magnetoencephalography system based on optically pumped magnetometers
Borna, A., Carter, T. R., Goldberg, J. D., Colombo, A. P., Jau, Y.-Y., Berry, C., McKay, J., Stephen, J., Weisend, M., & Schwindt, P. D. D. (2017) · Physics in Medicine and Biology · doi:10.1088/1361-6560/aa93d1 · Cited by 189
“Two recent simulation studies also demonstrate the distinct advantages of moving the sensors closer to the brain [4, 5].”
BackgroundIFCN-endorsed practical guidelines for clinical magnetoencephalography (MEG)
Hari, R., Baillet, S., Barnes, G. R., Burgess, R. C., Forss, N., Groß, J., Hämäläinen, M., Jensen, O. B., Kakigi, R., Mauguı̀ere, F., et al. (2018) · Clinical Neurophysiology · doi:10.1016/j.clinph.2018.03.042 · Cited by 179
“Moreover, they can be placed closer to the brain than the low-temperature SQUIDs, thereby providing better spatial resolution (Iivanainen et al., 2017), as long as their higher noise does not compromise this advantage.”
BackgroundHolmes, N., Tierney, T. M., Leggett, J., Boto, E., Mellor, S., Roberts, G., Hill, R. M., Shah, V., Barnes, G. R., Brookes, M. J., et al. (2019) · Scientific Reports · doi:10.1038/s41598-019-50697-w · Cited by 163
Magnetoencephalography in Cognitive Neuroscience: A Primer
Groß, J. (2019) · Neuron · doi:10.1016/j.neuron.2019.07.001 · Cited by 177
“The reduced distance between sensors and the brain leads to a significant increase in signal power, by a factor of 5–7, compared to SQUIDs (Iivanainen et al., 2017).”
BackgroundNon-Invasive Functional-Brain-Imaging with an OPM-based Magnetoencephalography System
Borna, A., Carter, T. R., Colombo, A. P., Jau, Y.-Y., McKay, J., Weisend, M., Taulu, S., Stephen, J. M., & Schwindt, P. D. D. (2020) · PLOS ONE · doi:10.1371/journal.pone.0227684 · Cited by 158
“7 have been reported in simulations consisting of dipolar brain sources and MEG sensors that are brought from the SQUID-related measurement distance onto the scalp [33].”
BackgroundTheoretical advantages of a triaxial optically pumped magnetometer magnetoencephalography system
Brookes, M. J., Boto, E., Rea, M., Shah, V., Osborne, J., Holmes, N., Hill, R. M., Leggett, J., Rhodes, N., & Bowtell, R. W. (2021) · NeuroImage · doi:10.1016/j.neuroimage.2021.118025 · Cited by 158
“(r12 is similar to the lead field correlation metric used in a previous study (Iivanainen et al., 2017).”
BackgroundResultInfluentialTowards OPM-MEG in a Virtual Reality Environment
Roberts, G., Holmes, N., Alexander, N., Boto, E., Leggett, J., Hill, R. M., Shah, V., Rea, M., Vaughan, R., Maguire, E. A., et al. (2019) · NeuroImage · doi:10.1016/j.neuroimage.2019.06.010 · Cited by 128
“Since the external surface of these sensors is approximately at body temperature, they can be brought within ~6-8 mm of the scalp surface, leading to a significant increase in the measurable signal (Boto et al., 2016; Iivanainen et al., 2017).”
BackgroundWearable neuroimaging: Combining and contrasting magnetoencephalography and electroencephalography
Boto, E., Seedat, Z. A., Holmes, N., Leggett, J., Hill, R. M., Roberts, G., Shah, V., Fromhold, T. M., Mullinger, K. J., Tierney, T. M., et al. (2019) · NeuroImage · doi:10.1016/j.neuroimage.2019.116099 · Cited by 136
“With scalpmounting, the sensing volume is positioned only millimetres from the scalp surface and the measured magnetic field is consequently higher compared to superconducting sensors (which are located further away), providing increased sensitivity (Boto et al., 2017, 2016; Iivanainen et al., 2017).”
BackgroundMeasuring functional connectivity with wearable MEG
Boto, E., Hill, R. M., Rea, M., Holmes, N., Seedat, Z. A., Leggett, J., Shah, V., Osborne, J., Bowtell, R. W., & Brookes, M. J. (2021) · NeuroImage · doi:10.1016/j.neuroimage.2021.117815 · Cited by 130
“Finally, because OPM sensors can get closer 13 to the brain, we can capture better data with higher sensitivity and spatial resolution (Boto et 14 al., 2019, 2016; Iivanainen et al., 2017).”
Borna, A., Iivanainen, J., Carter, T. R., McKay, J., Taulu, S., Stephen, J., & Schwindt, P. D. D. (2022) · NeuroImage · doi:10.1016/j.neuroimage.2021.118818 · Cited by 120
Self-citationPrecision magnetic field modelling and control for wearable magnetoencephalography
Rea, M., Holmes, N., Hill, R. M., Boto, E., Leggett, J., Edwards, L. J., Woolger, D., Dawson, E., Shah, V., Osborne, J., et al. (2021) · NeuroImage · doi:10.1016/j.neuroimage.2021.118401 · Cited by 123
“This, in turn, limits spatial resolution ( Boto et al., 016 ; Iivanainen et al., 2017 ).”
BackgroundInterference suppression techniques for OPM-based MEG: Opportunities and challenges
Seymour, R. A., Alexander, N., Mellor, S., O’Neill, G. C., Tierney, T. M., Barnes, G. R., & Maguire, E. A. (2021) · NeuroImage · doi:10.1016/j.neuroimage.2021.118834 · Cited by 131
“Detailed simulation work has shown that compared to radialnly oriented sensors, dual-axis and triaxial arrays of OPMs can theoetically measure neuromagnetic fields with greater information content nd increased signal amplitude ( Iivanainen et al., 2017 ).”
BackgroundA 90-Channel Triaxial Magnetoencephalography System Using Optically Pumped Magnetometers
Rea, M., Boto, E., Holmes, N., Hill, R., Osborne, J., Rhodes, N., Leggett, J., Rier, L., Bowtell, R., Shah, V., et al. (2022) · Annals of the New York Academy of Sciences · doi:10.1111/nyas.14890 · Cited by 102
Sensitive magnetometry in challenging environments
Fu, K. C., Iwata, G. Z., Wickenbrock, A., & Budker, D. (2020) · AVS Quantum Science · doi:10.1116/5.0025186 · Cited by 121
Using OPMs to measure neural activity in standing, mobile participants
Seymour, R. A., Alexander, N., Mellor, S., O'Neill, G. C., Tierney, T. M., Barnes, G. R., & Maguire, E. A. (2021) · NeuroImage · doi:10.1016/j.neuroimage.2021.118604 · Cited by 102
Potential of on‐scalp MEG: Robust detection of human visual gamma‐band responses
Iivanainen, J., Zetter, R., & Parkkonen, L. T. (2019) · Human Brain Mapping · doi:10.1002/hbm.24795 · Cited by 98
“OPMs, in contrast to SQUIDs, can be placed in very close proximity to the scalp, considerably boosting both spatial resolution and sensitivity to neural sources (Boto et al., 2016; Iivanainen et al., 2017).”
InfluentialSelf-citationAn integrated full-head OPM-MEG system based on 128 zero-field sensors
Alem, O., Hughes, K. J., Buard, I., Cheung, T., Maydew, T., Griesshammer, A., Holloway, K., Park, A., Lechuga, V., Coolidge, C., et al. (2023) · Frontiers in Neuroscience · doi:10.3389/fnins.2023.1190310 · Cited by 102
“4 times more spread for a cryogenic MEG (Iivanainen et al., 2017).”
BackgroundOptical Co-Registration of MRI and On-Scalp MEG
Zetter, R., Iivanainen, J., & Parkkonen, L. (2019) · Scientific Reports · doi:10.1038/s41598-019-41763-4 · Cited by 93
“Accurate co-registration is particularly important in on-scalp MEG [7] due to its high spatial resolution [2], [3].”
BackgroundSelf-citationFaley, M. I., Dammers, J., Maslennikov, Y. V., Schneiderman, J. F., Winkler, D., Koshelets, V. P., Shah, N. J., & Dunin‐Borkowski, R. E. (2017) · Superconductor Science and Technology · doi:10.1088/1361-6668/aa73ad · Cited by 95
“Theoretical studies [7, 8] have shown that atomic magnetometers can provide a higher SNR and potentially replace SQUIDs in MEG systems.”
BackgroundTowards an objective evaluation of EEG/MEG source estimation methods – The linear approach
Hauk, O., Stenroos, M., & Treder, M. S. (2022) · NeuroImage · doi:10.1016/j.neuroimage.2022.119177 · Cited by 92
“rather than the peak to compute localization error, or spatial extent has been evaluated using measures of area (Iivanainen et al., 2017).”
BackgroundMethodResultInfluentialSelf-citationMouth magnetoencephalography: A unique perspective on the human hippocampus
Tierney, T. M., Levy, A. D., Barry, D. N., Meyer, S. S., Shigihara, Y., Everatt, M., Mellor, S., López, J. D., Bestmann, S., Holmes, N., et al. (2020) · NeuroImage · doi:10.1016/j.neuroimage.2020.117443 · Cited by 87
Nardelli, N. V., Perry, A. R., Krzyzewski, S., & Knappe, S. A. (2020) · EPJ Quantum Technology · doi:10.1140/epjqt/s40507-020-00086-4 · Cited by 85
Measurement of Frontal Midline Theta Oscillations using OPM-MEG
Rhodes, N., Rea, M., Boto, E., Rier, L., Shah, V., Hill, R. M., Osborne, J., Doyle, C., Holmes, N., Coleman, S. C., et al. (2023) · NeuroImage · doi:10.1016/j.neuroimage.2023.120024 · Cited by 91
Magnetoencephalography with a Cs-based high-sensitivity compact atomic magnetometer
Sheng, J., Wan, S., Sun, Y., Dou, R., Guo, Y., Wei, K., He, K., Qin, J., & Gao, J. (2017) · Review of Scientific Instruments · doi:10.1063/1.5001730 · Cited by 80
Reducing crosstalk in optically-pumped magnetometer arrays
Nardelli, N. V., Krzyzewski, S., & Knappe, S. A. (2019) · Physics in Medicine and Biology · doi:10.1088/1361-6560/ab4c06 · Cited by 81
“Recent studies simulating whole-head MEG systems with on-scalp sensors promise greatly increased spatial resolution compared to the current SQUID-based MEG systems (Luessi et al 2014, Boto et al 2016, Iivanainen et al 2017).”
Using OPM-MEG in contrasting magnetic environments
Hill, R. M., Devasagayam, J., Holmes, N., Boto, E., Shah, V., Osborne, J., Safar, K., Worcester, F., Mariani, C., Dawson, E., et al. (2022) · NeuroImage · doi:10.1016/j.neuroimage.2022.119084 · Cited by 85
Imaging the human hippocampus with optically-pumped magnetoencephalography
Barry, D. N., Tierney, T. M., Holmes, N., Boto, E., Roberts, G., Leggett, J., Bowtell, R. W., Brookes, M. J., Barnes, G. R., & Maguire, E. A. (2019) · NeuroImage · doi:10.1016/j.neuroimage.2019.116192 · Cited by 76
Laminar dynamics of high amplitude beta bursts in human motor cortex
Bonaiuto, J. J., Little, S., Neymotin, S. A., Jones, S. R., Barnes, G. R., & Bestmann, S. (2021) · NeuroImage · doi:10.1016/j.neuroimage.2021.118479 · Cited by 76
“…layers, and higher SNR data afforded by cryogen- ree MEG sensors (optically-pumped magnetometers; OPMs; Boto et al., 016, 2018; Holmes et al., 2018; Iivanainen et al., 2017, 2019; Knappe t al., 2014 ), may be able to use an approach similar to current source ensity methods ( Pettersen et al.,…”
MethodOptically pumped magnetoencephalography in epilepsy
Vivekananda, U., Mellor, S., Tierney, T. M., Holmes, N., Boto, E., Leggett, J., Roberts, G., Hill, R. M., Vladimir Litvak, A., Brookes, M. J., et al. (2020) · Annals of Clinical and Translational Neurology · doi:10.1002/acn3.50995 · Cited by 75
Jodko-Władzińska, A., Wildner, K., Pałko, T., & Władziński, M. (2020) · Sensors · doi:10.3390/s20164563 · Cited by 74
“Flexible optical and electrical wiring of OPMs, together with a small size sensor head, enable minimizing the sensor-signal source distance, which leads to higher amplitudes of received signal [27,28].”
BackgroundMagnetoencephalography With Optically Pumped4He Magnetometers at Ambient Temperature
Labyt, É., Corsi, M., Fourcault, W., Laloy, A. P., Bertrand, F., Lenouvel, F., Cauffet, G., Prado, M. L., Berger, F. R., & Morales, S. (2018) · IEEE Transactions on Medical Imaging · doi:10.1109/tmi.2018.2856367 · Cited by 72
“This result well agrees with a recent work [53] quantifying the improvement in recording MEG with simulated on-scalp OPM arrays compared to a 306-channels SQUID array such as Vectorview Neuromag MEG machine used in our study.”
ResultOptically Pumped Magnetometers Recent Advances and Applications in Biomagnetism: A Review
Zhao, B., Li, L., Zhang, Y., Tang, J., Liu, Y., & Zhai, Y. (2023) · IEEE Sensors Journal · doi:10.1109/jsen.2023.3297109 · Cited by 74
“[25], [26], [27], [28], [29], [30], [33], [34], [35], [36], [37], [38], [39], [40], and magnetomyography (MMG) [41].”
Manyukhina, V. O., Prokofyev, A. O., Galuta, I. A., Goiaeva, D. E., Obukhova, T. S., Schneiderman, J. F., Altukhov, D., Stroganova, T. A., & Orekhova, E. V. (2022) · Molecular Autism · doi:10.1186/s13229-022-00498-2 · Cited by 81
“Thirdly, the new and rapidly developing technology of ‘on-scalp’ MEG (65-67) may help to obtain equally high-quality data in all parts of the head, including the frontal areas, which are typically positioned furthest away from the sensors in ‘conventional’ MEG systems.”
BackgroundNann, M., Cordella, F., Trigili, E., Lauretti, C., Bravi, M., Miccinilli, S., Catalan, J. M., Badesa, F. J., Crea, S., Bressi, F., et al. (2020) · IEEE Systems Journal · doi:10.1109/jsyst.2020.3021485 · Cited by 71
“quantum sensors [34], [35], may overcome the current constraint of limited spatial resolution when recording brain oscillatory activity noninvasively.”
BackgroundZhang, G., Huang, S.-J., Xu, F., Hu, Z., & Lin, Q. (2019) · Optics Express · doi:10.1364/oe.27.000597 · Cited by 64
He, K., Wan, S., Sheng, J., Liu, D., Wang, C., Li, D., Qin, L., Luo, S., Qin, J., & Gao, J. (2019) · Review of Scientific Instruments · doi:10.1063/1.5066250 · Cited by 63
Transforming and comparing data between standard SQUID and OPM-MEG systems
Marhl, U., Jodko-Władzińska, A., Brühl, R., Sander, T. H., & Jazbinšek, V. (2022) · PLoS ONE · doi:10.1371/journal.pone.0262669 · Cited by 66
Long, T., Song, X., Han, B., Suo, Y., & Jia, L. (2023) · IEEE Transactions on Instrumentation and Measurement · doi:10.1109/tim.2023.3331425 · Cited by 62
“As a result, the OPM achieves an enhanced signal strength, typically offering a three-to fivefold improvement by reducing the distance between the sensor and the subject’s brain [19], [20].”
BackgroundScalp attached tangential magnetoencephalography using tunnel magneto-resistive sensors
Kanno, A., Nakasato, N., Oogane, M., Fujiwara, K., Nakano, T., Arimoto, T., Matsuzaki, H., & Ando, Y. (2022) · Scientific Reports · doi:10.1038/s41598-022-10155-6 · Cited by 62
Ru, X., He, K., Lyu, B., Li, D., Xu, W., Gu, W., Ma, X., Liu, J., Li, C., Li, T., et al. (2022) · NeuroImage · doi:10.1016/j.neuroimage.2022.119420 · Cited by 57
Characterizing hippocampal dynamics with MEG: A systematic review and evidence‐based guidelines
Ruzich, E., Crespo‐García, M., Dalal, S. S., & Schneiderman, J. F. (2018) · Human Brain Mapping · doi:10.1002/hbm.24445 · Cited by 58
“These systems, still in development, are demonstrated to have comparable or better SNRs to classic MEG, and suggest their potential utility to measure a broader range of brain activity from deeper structures (Boto et al., 2016; Boto et al., 2018; Iivanainen et al., 2017; Öisjöen et al., 2012; Schneiderman, 2014).”
BackgroundApplications of OPM-MEG for translational neuroscience: a perspective
Brickwedde, M., Anders, P., Kühn, A. A., Lofredi, R., Holtkamp, M., Kaindl, A. M., Grent-‘t-Jong, T., Krüger, P., Sander, T. H., & Uhlhaas, P. J. (2024) · Translational Psychiatry · doi:10.1038/s41398-024-03047-y · Cited by 59
Requirements for Coregistration Accuracy in On-Scalp MEG
Zetter, R., Iivanainen, J., Stenroos, M., & Parkkonen, L. T. (2018) · Brain Topography · doi:10.1007/s10548-018-0656-5 · Cited by 61
“Since sensitivity and spatial resolution are related to the distance between the sources and the sensors, the need of cryogenics eventually results in a considerable loss of signal amplitude and spatial resolution (Boto et al., 2016; Iivanainen et al., 2017).”
BackgroundMethodInfluentialSelf-citationOptimal design of on‐scalp electromagnetic sensor arrays for brain source localisation
Beltrachini, L., von Ellenrieder, N., Eichardt, R., & Haueisen, J. (2021) · Human Brain Mapping · doi:10.1002/hbm.25586 · Cited by 53
Spherical harmonic based noise rejection and neuronal sampling with multi-axis OPMs
Tierney, T. M., Mellor, S., O’Neill, G. C., Timms, R. C., & Barnes, G. R. (2022) · NeuroImage · doi:10.1016/j.neuroimage.2022.119338 · Cited by 57
“With regards to limitations we have not explored the implications of important effects such as volume currents which can be larger for tangential measurements (Iivanainen et al., 2017) or the impact of different forward models (Stenroos et al.”
BackgroundHillebrand, A., Holmes, N., Sijsma, N., O’Neill, G. C., Tierney, T. M., Liberton, N., Stam, A. H., van Klink, N. E. C., Stam, C. J., Bowtell, R. W., et al. (2023) · Scientific Reports · doi:10.1038/s41598-023-31111-y · Cited by 58
Gutteling, T. P., Bonnefond, M., Clausner, T., Daligault, S., Romain, R., Mitryukovskiy, S. I., Fourcault, W., Josselin, V., Prado, M. L., Palacios-Laloy, A., et al. (2023) · Sensors · doi:10.3390/s23052801 · Cited by 52
Magnetic Source Imaging Using a Pulsed Optically Pumped Magnetometer Array
Borna, A., Carter, T. R., DeRego, P., James, C. D., & Schwindt, P. D. D. (2018) · IEEE Transactions on Instrumentation and Measurement · doi:10.1109/tim.2018.2851458 · Cited by 51
Naturalistic Hyperscanning with Wearable Magnetoencephalography
Holmes, N., Rea, M., Hill, R. M., Boto, E., Leggett, J., Edwards, L. J., Rhodes, N., Shah, V., Osborne, J., Fromhold, T. M., et al. (2023) · Sensors · doi:10.3390/s23125454 · Cited by 52
“Increased proximity to the scalp can improve sensitivity and spatial resolution beyond that which is achieved using a cryogenic MEG [26,27].”
BackgroundMethodPragmatic spatial sampling for wearable MEG arrays
Tierney, T. M., Mellor, S., O’Neill, G. C., Holmes, N., Boto, E., Roberts, G., Hill, R. M., Leggett, J., Bowtell, R. W., Brookes, M. J., et al. (2020) · Scientific Reports · doi:10.1038/s41598-020-77589-8 · Cited by 51
Spatial sampling of MEG and EEG based on generalized spatial-frequency analysis and optimal design
Iivanainen, J., Mäkinen, A. J., Zetter, R., Stenroos, M., Ilmoniemi, R. J., & Parkkonen, L. T. (2021) · NeuroImage · doi:10.1016/j.neuroimage.2021.118747 · Cited by 53
“In contrast, magnetic field is a vector field, and the orthog512 onal field components may each provide additional information about the neural sources (Iivanainen et al., 2017).”
BackgroundMethodInfluentialSelf-citationNugent, A. C., Benitez Andonegui, A., Holroyd, T., & Robinson, S. E. (2022) · Neuroimage: Reports · doi:10.1016/j.ynirp.2022.100093 · Cited by 41
“The simplest simulation involves measuring signal to noise; simulating a single dipole predicts a ten-fold increase in SNR for an on-scalp whole head system compared to a traditional axial gradiometer SQUID MEG system (Iivanainen et al., 2017).”
MethodMiniature Biplanar Coils for Alkali-Metal-Vapor Magnetometry
Tayler, M. C. D., Mouloudakis, K., Zetter, R., Hunter, D., Lucivero, V. G., Bodenstedt, S., Parkkonen, L. T., & Mitchell, M. W. (2022) · Physical Review Applied · doi:10.1103/physrevapplied.18.014036 · Cited by 48
Self-citationPratt, E. J., Ledbetter, M. P., Jiménez-Martínez, R., Shapiro, B., Solon, A. J., Iwata, G. Z., Garber, S., Gormley, J., Decker, D., Delgadillo, D., et al. (2021) · Optical and Quantum Sensing and Precision Metrology · doi:10.1117/12.2581794 · Cited by 44
Schofield, H., Hill, R. M., Feys, O., Holmes, N., Osborne, J., Doyle, C., Bobela, D., Corvilain, P., Wens, V., Rier, L., et al. (2024) · Imaging Neuroscience · doi:10.1162/imag_a_00283 · Cited by 54
“…cryogenic devices, as a thermally insulating gap is no longer required); this improves signal amplitude significantly ( Boto et al., 2016, 2017; Iivanainen et al., 2017, 2019, 2020) and theoretical calculations suggest this can offer improved spatial resolution (higher than conventional MEG…”
BackgroundEvaluation of realistic layouts for next generation on-scalp MEG: spatial information density maps
Riaz, B., Pfeiffer, C., & Schneiderman, J. F. (2017) · Scientific Reports · doi:10.1038/s41598-017-07046-6 · Cited by 43
Integrated Giant Magnetoresistance Technology for Approachable Weak Biomagnetic Signal Detections
Shen, H., Hu, L., & Fu, X. H. (2018) · Sensors · doi:10.3390/s18010148 · Cited by 42
“improve temporal and spatial resolutions, since the signal magnitude will be greater with the reduced distance between sensor and tissues [58,59].”
BackgroundPractical real-time MEG-based neural interfacing with optically pumped magnetometers
Wittevrongel, B., Holmes, N., Boto, E., Hill, R. M., Rea, M., Libert, A., Khachatryan, E., Hulle, M. M. V., Bowtell, R. W., & Brookes, M. J. (2021) · BMC Biology · doi:10.1186/s12915-021-01073-6 · Cited by 47
Exploring the limits of MEG spatial resolution with multipolar expansions
Wens, V. (2023) · NeuroImage · doi:10.1016/j.neuroimage.2023.119953 · Cited by 44
Schofield, H., Boto, E., Shah, V., Hill, R. M., Osborne, J., Rea, M., Doyle, C., Holmes, N., Bowtell, R. W., Woolger, D., et al. (2022) · Contemporary Physics · doi:10.1080/00107514.2023.2182950 · Cited by 46
“Sensor proximity is important due to the inverse square law and simulations suggest that scalp-based measurement offers 4–5 times higher signal strength from most cortical sources, compared to SQUID based measurements [29,30].”
BackgroundCichy, R. M., & Teng, S. (2017) · Philosophical Transactions of the Royal Society B Biological Sciences · doi:10.1098/rstb.2016.0108 · Cited by 41
Andersen, L. M., Oostenveld, R., Pfeiffer, C., Ruffieux, S., Jousmäki, V., Hämäläinen, M., Schneiderman, J. F., & Lundqvist, D. (2017) · PLoS ONE · doi:10.1371/journal.pone.0178602 · Cited by 39
“Simulations have indicated on-scalp MEG promises improved spatial precision in estimating the location of neural sources and better separation of source activations [16,17].”
BackgroundPeripheral Nerve Magnetoneurography With Optically Pumped Magnetometers
Bu, Y., Prince, J., Mojtahed, H., Kimball, D. F., Shah, V., Coleman, T. P., Sarkar, M., Rao, R., Huang, M., Schwindt, P. D. D., et al. (2022) · Frontiers in Physiology · doi:10.3389/fphys.2022.798376 · Cited by 36
The impact of improved MEG–MRI co-registration on MEG connectivity analysis
Chella, F., Marzetti, L., Stenroos, M., Parkkonen, L. T., Ilmoniemi, R. J., Romani, G. L., & Pizzella, V. (2019) · NeuroImage · doi:10.1016/j.neuroimage.2019.04.061 · Cited by 39
“In conventional MEG devices, the dewar walls of the MEG helmet are approximately 2 cm thick (as reported in, e.g., Iivanainen et al., 2017); thus the head was reasonably close to the dewar surface, as recommended in real-world measurements.”
Self-citationMEG Sensor Selection for Neural Speech Decoding
Dash, D., Wisler, A. A., Ferrari, P., Davenport, E. M., Maldjian, J. A., & Wang, J. (2020) · IEEE Access · doi:10.1109/access.2020.3028831 · Cited by 40
“The OPM-MEG (on-scalp-MEG) system improves sensor-to-cortex proximity compared to the conventional MEG (in-helmet-MEG) systems thereby providing improved spatial resolution, higher signal magnitude, and better separation of source activations [54], [55].”
MethodAn, N., Cao, F., Wen, L., Wang, W., Xu, W., Wang, C., Xiang, M., Gao, Y., Sui, B., Liang, A., et al. (2022) · iScience · doi:10.1016/j.isci.2022.103752 · Cited by 36
“In particular, OPM-MEG has attracted the attention of researchers owing to its wearable and flexible sensor configuration (Boto et al., 2018; Iivanainen et al., 2017).”
BackgroundBoundary Element Fast Multipole Method for Enhanced Modeling of Neurophysiological Recordings
Makarov, S. N., Hämäläinen, M., Okada, Y. C., Noetscher, G. M., Ahveninen, J., & Nummenmaa, A. R. (2020) · IEEE Transactions on Biomedical Engineering · doi:10.1109/tbme.2020.2999271 · Cited by 37
“The same is valid for more accurate MEG measurement techniques [20], [21].”
MethodA 7-Channel High-${T}_\text{c}$ SQUID-Based On-Scalp MEG System
Pfeiffer, C., Ruffieux, S., Jönsson, L., Chukharkin, M. L., Kalaboukhov, A., Xie, M., Winkler, D., & Schneiderman, J. F. (2019) · IEEE Transactions on Biomedical Engineering · doi:10.1109/tbme.2019.2938688 · Cited by 41
Measuring the cortical tracking of speech with optically-pumped magnetometers
de Lange, P., Boto, E., Holmes, N., Hill, R. M., Bowtell, R. W., Wens, V., Tiège, X. D., Brookes, M. J., & Bourguignon, M. (2021) · NeuroImage · doi:10.1016/j.neuroimage.2021.117969 · Cited by 37
“expected (Boto et al., 2016; Iivanainen et al., 2017), these field patterns were more focal than those typically seen in SQUID–MEG or EEG studies.”
Concurrent spinal and brain imaging with optically pumped magnetometers
Mardell, L. C., Spedden, M. E., O’Neill, G. C., Tierney, T. M., Timms, R. C., Zich, C., Barnes, G. R., & Bestmann, S. (2024) · Journal of Neuroscience Methods · doi:10.1016/j.jneumeth.2024.110131 · Cited by 36
Evolution of MEG : A first MEG ‐feasible fluxgate magnetometer
Koshev, N., Butorina, A. V., Skidchenko, E., Kuzmichev, A. N., Ossadtchi, A. E., Ostras, M., Fedorov, M. V., & Vetoshko, P. M. (2021) · Human Brain Mapping · doi:10.1002/hbm.25582 · Cited by 34
“Also Iivanainen et al. (2017) show much higher total information capacity of the sensor array when sensors are located closer to the head surface.”
BackgroundWardle, S. G., & Baker, C. I. (2020) · F1000Research · doi:10.12688/f1000research.22296.1 · Cited by 30
Detection and analysis of cortical beta bursts in developmental EEG data
Rayson, H., Debnath, R., Alavizadeh, S., Fox, N. A., Ferrari, P. F., & Bonaiuto, J. J. (2022) · Developmental Cognitive Neuroscience · doi:10.1016/j.dcn.2022.101069 · Cited by 34
“…2018; Nakano et al., 2020; Pereira et al., 2018), and EEG alternatives such as newly developed, cryogen-free MEG sensors (Boto et al., 2018, 2017, 2016; Iivanainen et al., 2019, 2017; Knappe et al., 2014) which have to potential to allow acquisition of high SNR data from developmental populations.”
BackgroundOptical Co-Registration Method of Triaxial OPM-MEG and MRI
Cao, F., An, N., Xu, W., Wang, W., Li, W., Wang, C., Xiang, M., Gao, Y., & Ning, X. (2023) · IEEE Transactions on Medical Imaging · doi:10.1109/tmi.2023.3263167 · Cited by 32
“Meanwhile, the addition of two tangential components has the potential to improve the sensitivity of OPM-MEG to the tangential and the volume source [15].”
Long, T., Song, X., Duan, Z., Suo, Y., Wu, Z., Jia, L., & Han, B. (2023) · IEEE Transactions on Instrumentation and Measurement · doi:10.1109/tim.2023.3341139 · Cited by 31
“This is attributed to the inverse square relationship between the amplitude of the magnetic field and the distance [13].”
BackgroundTest-retest reliability of the human connectome: An OPM-MEG study
Rier, L., Michelmann, S., Ritz, H., Shah, V., Hill, R. M., Osborne, J., Doyle, C., Holmes, N., Bowtell, R. W., Brookes, M. J., et al. (2023) · Imaging Neuroscience · doi:10.1162/imag_a_00020 · Cited by 32
“Improved data quality has been shown in both theory ( Boto et al., 2016; Iivanainen et al., 2017) and practice ( Boto et al., 2017), including during subject movement (e.g. Boto et al., 2018), though recording during active movement critically depends on background field control ( Holmes et al.,…”
BackgroundLocalizing on-scalp MEG sensors using an array of magnetic dipole coils
Pfeiffer, C., Andersen, L. M., Lundqvist, D., Hämäläinen, M., Schneiderman, J. F., & Oostenveld, R. (2018) · PLoS ONE · doi:10.1371/journal.pone.0191111 · Cited by 35
Calibration and Localization of Optically Pumped Magnetometers Using Electromagnetic Coils
Iivanainen, J., Borna, A., Zetter, R., Carter, T. R., Stephen, J. M., McKay, J., Parkkonen, L. T., Taulu, S., & Schwindt, P. D. D. (2022) · Sensors · doi:10.3390/s22083059 · Cited by 34
“In contrast to SQUIDs, which detect the field at least ~2 cm from the scalp, these optically pumped magnetometers (OPMs) can measure the magnetic field within millimeters from the scalp, increasing the signal magnitude and the spatial resolution of the measurement [9,10].”
BackgroundSelf-citationZahran, S., Mahmoudzadeh, M., Wallois, F., Betrouni, N., Derambure, P., Prado, M. L., Palacios-Laloy, A., & Labyt, É. (2022) · Sensors · doi:10.3390/s22083093 · Cited by 34
“Here, we only discuss the results obtained for the adult head model, for easier comparison with previous simulation studies of alkali OPMs and adult head models [14,15].”
BackgroundMethodResultInfluentialOn-scalp MEG SQUIDs are sensitive to early somatosensory activity unseen by conventional MEG
Andersen, L. M., Pfeiffer, C., Ruffieux, S., Riaz, B., Winkler, D., Schneiderman, J. F., & Lundqvist, D. (2020) · NeuroImage · doi:10.1016/j.neuroimage.2020.117157 · Cited by 28
Simulation Study of Different OPM-MEG Measurement Components
Marhl, U., Sander, T. H., & Jazbinšek, V. (2022) · Sensors · doi:10.3390/s22093184 · Cited by 31
“This was already shown in a couple of previous works [6,7], and it was also confirmed by our results in Tables 1 and 2, where we show that the OPM-MEG configurations have an RMSsignal around 2.”
BackgroundResultContactless measurements of retinal activity using optically pumped magnetometers
Westner, B. U., Lubell, J. I., Jensen, M., Hokland, S., & Dalal, S. S. (2021) · NeuroImage · doi:10.1016/j.neuroimage.2021.118528 · Cited by 29
“…can rather be placed ndividually and close to the scalp, which has yielded better signalo-noise ratio (SNR) for measurements of brain activity in simulations Boto et al., 2016; Iivanainen et al., 2017 ) and real recordings ( Boto t al., 2018; 2017; Hill et al., 2020; Iivanainen et al., 2020 ).”
BackgroundPfeiffer, C., Ruffieux, S., Andersen, L. M., Kalabukhov, A., Winkler, D., Oostenveld, R., Lundqvist, D., & Schneiderman, J. F. (2020) · NeuroImage · doi:10.1016/j.neuroimage.2020.116686 · Cited by 28
“At 3 closer proximity to the head –and thus to the neural sources– on-scalp MEG 4 should be able to measure weaker signals as well as capture higher spatial fre5 quencies compared to conventional MEG [1, 2].”
Simultaneous whole-head electrophysiological recordings using EEG and OPM-MEG
Seedat, Z. A., Pier, K. S., Holmes, N., Rea, M., Al-Hilaly, L., Tierney, T. M., Embury, C. M., Pardington, R., Mullinger, K. J., Cross, J. H., et al. (2024) · Imaging Neuroscience · doi:10.1162/imag_a_00179 · Cited by 29
“Because OPMs can get closer to the scalp than cryogenic sensors, they detect a signal that is less spatially diffuse and higher amplitude, bringing improved sensitivity and spatial resolution ( Borna et al., 2017; Boto et al., 2016; Iivanainen et al., 2017; Nugent et al., 2022).”
BackgroundHolmes, N., Bowtell, R. W., Brookes, M. J., & Taulu, S. (2023) · Sensors · doi:10.3390/s23146537 · Cited by 33
Hill, R. M., Schofield, H., Boto, E., Rier, L., Osborne, J., Doyle, C., Worcester, F., Hayward, T., Holmes, N., Bowtell, R. W., et al. (2024) · Imaging Neuroscience · doi:10.1162/imag_a_00112 · Cited by 29
“They also show experimental evidence of the high importance of expanding OPM-MEG systems to higher channel count (which has been highlighted by previous theory papers (e.g., Boto et al., 2016; Iivanainen et al., 2017).”
BackgroundResultTowards the Non-Zero Field Cesium Magnetic Sensor Array for Magnetoencephalography
Petrenko, M. V., Dmitriev, S. P., Pazgalev, A. S., Ossadtchi, A. E., & Vershovskii, A. K. (2021) · IEEE Sensors Journal · doi:10.1109/jsen.2021.3089455 · Cited by 24
Data‐driven model optimization for optically pumped magnetometer sensor arrays
Duque‐Muñoz, L., Tierney, T. M., Meyer, S. S., Boto, E., Holmes, N., Roberts, G., Leggett, J., Vargas‐Bonilla, J. F., Bowtell, R. W., Brookes, M. J., et al. (2019) · Human Brain Mapping · doi:10.1002/hbm.24707 · Cited by 24
“Additionally, we have measurements of magnetic fields tangential (rather than radial) to the cortical surface that we still have not used (Iivanainen et al., 2017).”
MethodEffects of Different Head Models in Wearable OPM-MEG
Cao, F., An, N., Wang, W., Xu, W., Li, W., Wang, C., Xiang, M., Gao, Y., & Ning, X. (2022) · IEEE Transactions on Instrumentation and Measurement · doi:10.1109/tim.2022.3192287 · Cited by 24
Single-trial classification of evoked responses to auditory tones using OPM- and SQUID-MEG
Iivanainen, J., Carter, T. R., Trumbo, M., McKay, J., Taulu, S., Wang, J., Stephen, J. M., Schwindt, P. D. D., & Borna, A. (2023) · Journal of Neural Engineering · doi:10.1088/1741-2552/acfcd9 · Cited by 24
“In contrast to SQUIDs, OPMs enable wearable sensor arrays detecting the field within millimeters from the scalp increasing the usability and spatial resolution of MEG (Iivanainen et al 2017, Boto et al 2018).”
Self-citationBadier, J., Schwartz, D., Bénar, C., Kanzari, K., Daligault, S., Romain, R., Mitryukovskiy, S. I., Fourcault, W., Josselin, V., Prado, M. L., et al. (2023) · eNeuro · doi:10.1523/eneuro.0222-23.2023 · Cited by 22
“The additional information offered by a vectorial measurement of the magnetic field, also reported in the present study, will be of interest to better characterize the spatiotemporal dynamics of epileptic activity and to interpret clinical data (Iivanainen et al., 2017; Zahran et al., 2022).”
BackgroundResultInfluentialNew Cognitive Neurotechnology Facilitates Studies of Cortical–Subcortical Interactions
Min, B., Hämäläinen, M., & Pantazis, D. (2020) · Trends in biotechnology · doi:10.1016/j.tibtech.2020.03.003 · Cited by 26
“This allows the OPMs to be placed within millimeters from the scalp, and the sensor array can be adapted to the size and shape of the subject’s head, substantially increasing spatial resolution [34, 35].”
BackgroundMethodTriaxial Vector Operation in Near-Zero Field of Atomic Magnetometer With Femtotesla Sensitivity
Lu, F., Lu, J., Li, B., Yan, Y., Zhang, S., Yin, K., Ye, M., & Han, B. (2022) · IEEE Transactions on Instrumentation and Measurement · doi:10.1109/tim.2022.3162282 · Cited by 23
Metadata
- Authors
- Iivanainen, J., Stenroos, M., & Parkkonen, L.
- Affiliations
- Aalto University (FI)
- Corresponding author
- Iivanainen, Joonas
- Venue
- NeuroImage
- Publisher
- Elsevier BV
- Published
- 2017-02
- Volume
- 147
- Pages
- 542-553
- ISSN
- 1053-8119 (ISSN-L)
- PMC
- PMC5432137
- OpenAlex
- W2949327983
- Cited by
- 296
- References
- 47
- Citations by year
- 2026: 28 · 2025: 49 · 2024: 39 · 2023: 40 · 2022: 36 · 2021: 30 · 2020: 25 · 2019: 32 · 2018: 10 · 2017: 7
- FWCI
- 7.72
- Type
- journal article
- Language
- en
- Open access
- hybrid
- doi.org
- Licence
- Locations
- NeuroImage (publishedVersion, cc-by-nc-nd)
- bioRxiv (Cold Spring Harbor Laboratory) (acceptedVersion, cc-by-nc-nd)
- PubMed (publishedVersion)
- PubMed Central (acceptedVersion)
- Aaltodoc (Aalto University) (submittedVersion, cc-by-nc-nd)
- Funders
- National Institute of Neurological Disorders and Stroke
- Seventh Framework Programme (600730)
- National Institutes of Health (R01NS094604)
- Topics
- Physical Sciences › Physics and Astronomy › Atomic and Molecular Physics, and Optics › Atomic and Subatomic Physics Research
- Physical Sciences › Engineering › Electrical and Electronic Engineering › Magnetic Field Sensors Techniques
- Life Sciences › Neuroscience › Cognitive Neuroscience › EEG and Brain-Computer Interfaces
- Keywords
- magnetoencephalography, optically pumped magnetometers, SQUID magnetometer, planar gradiometer, forward modeling, boundary element model, dipole source localization, point spread function, information capacity, volume currents, signal-to-noise ratio
- MeSH terms
- Adult, Brain, Female, Humans, Male, Models, Theoretical, Scalp, Signal Processing, Computer-Assisted, Magnetoencephalography
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