Combined encephalography (OPM-EMEG project)



Fig 1. Scheme of source localization in case of combined EEG/MEG measurements

The OPM-EMEG project is devoted to the development of an encephalography system, based on a small number of optically pumped magnetometers (OPMs) combined with EEG. The aim is to develop a comparatively cheap EMEG system with the spatial resolution comparable to much more expensive conventional MEG-systems containing 100-500 sensors. The idea of the project is based on previously developed by the Skoltech’s group algorithms for processing the OPM-MEG and EEG data, including a set of methods for scalp-to-cortex extrapolation of the electric potential via a solution of the ill-posed Cauchy problem for the elliptic differential equation (see Fig. 4), and two-stage algorithm for the solution of the source localization problem for combined MEG/EEG measurements (see Fig.3).

Fig 2. Mapping the EEG data from scalp (left) to cortex (right)

1. Borna, A., Carter, T. R., Goldberg, J. D., Colombo, A. P., Jau, Y. Y., Berry, C., ... & Schwindt, P. D. (2017). A 20-channel magnetoencephalography system based on optically pumped magnetometers. Physics in Medicine & Biology, 62(23), 8909.
2. Boto, E., Holmes, N., Leggett, J., Roberts, G., Shah, V., Meyer, S. S., ... & Barnes, G. R. (2018). Moving magnetoencephalography towards real-world applications with a wearable system. Nature, 555(7698), 657-661.
3. Iivanainen J, Zetter R, Parkkonen L. Potential of on-scalp MEG: Robust detection of human visual gamma-band responses. Hum Brain Mapp. 2020;41:150–161.
4. Tierney, T. M., Holmes, N., Meyer, S. S., Boto, E., Roberts, G., Leggett, J., ... & Baldeweg, T. (2018). Cognitive neuroscience using wearable magnetometer arrays: Non-invasive assessment of language function. NeuroImage, 181, 513-520.
5. Lin, C. H., Tierney, T. M., Holmes, N., Boto, E., Leggett, J., Bestmann, S., ... & Miall, R. C. (2019). Using optically pumped magnetometers to measure magnetoencephalographic signals in the human cerebellum. The Journal of physiology, 597(16), 4309-4324.
6. R. Zetter et al. “Optical co-registration of MRI and on-scalp MEG, Scientific Reports (2019) 9:5490.
7. R.M. Hill et al. “Multi-Channel Whole-Head OPM-MEG: Helmet Design and a Comparison with a Conventional System, bioRxiv preprint posted March 13, 2020.
8. Jaufenthaler et al. “Quantitative 2D Magnetorelaxometry Imaging of Magnetic Nanoparticles Using Optically Pumped Magnetometers” Sensors 2019, 20, 753;
9. Borna et al. “Non-Invasive Functional-Brain-Imaging with an OPM-based Magnetoencephalography System” PLoS ONE (2020) 15 (1): e0227684
10. Razorenova A., Yavich N., Malovichko M., Fedorov M., Koshev N., Dylov D., Deep Learning for Cortical Potential Imaging, submitted to MICCAI 2020.
11. Koshev, Nikolay; Yavich, Nikolay; Malovichko, Mikhail; Skidchenko, Ekaterina; Fedorov, Maxim; FEM-based Scalp-to-Cortex EEG data mapping via the solution of the Cauchy problem,Journal of Inverse and Ill-posed Problems,1,ahead-of-print,,2020,De Gruyter