MEG is a functional neuroimaging method that allows us to directly measure neural signaling with millisecond precision by recording the weak magnetic fields generated by neural currents in the brain. Similar to EEG, it allows us to not only localize neural activity but also to tease apart their temporal dynamics (Hari and Parkkonen, 2015). 

Recent sensor developments have led to the emergence of on-scalp MEG. On-scalp MEG uses novel sensors called optically pumped magnetometers or OPMs that operate at less extreme temperatures. As a result, they require significantly less thermal insulation leading to smaller, lighter sensors that can be placed closer to the participant’s head – and the neural sources therein. By recording closer, to the head on-scalp MEG can achieve higher sensitivity and spatial precision (Iivanainen et al., 2017). The small size and weight of the sensors also brings new possibilities in how to record. Unlike the fixed, one-size-fits-all sensor array in conventional MEG, on-scalp MEG sensor arrays can be adjusted to the head of the individual participant or even worn on the head like EEG electrodes to allow head movement (Boto et al., 2018). Being able to adjust the size is especially promising for developmental studies. The same scanner can be used to measure children and adults without compromising sensitivity (Hill et al., 2019).

Location

SUBIC seminar room or Zoom 

MEG recordings at NatMEG in a conventional MEG scanner (top) and a next-gen on-scalp MEG scanner (bottom) (Image source: natmeg.se)

References

1. Boto, E., Holmes, N., Leggett, J., Roberts, G., Shah, V., Meyer, S.S., Muñoz, L.D., Mullinger, K.J., Tierney, T.M., Bestmann, S., Barnes, G.R., Bowtell, R., Brookes, M.J., 2018. Moving magnetoencephalography towards real-world applications with a wearable system. Nature 555, 657–661. https://doi.org/10.1038/nature26147
2. Hari, R., Parkkonen, L., 2015. The brain timewise: how timing shapes and supports brain function. Philos. Trans. R. Soc. B Biol. Sci. 370, 20140170. https://doi.org/10.1098/rstb.2014.0170
3. Hill, R.M., Boto, E., Holmes, N., Hartley, C., Seedat, Z.A., Leggett, J., Roberts, G., Shah, V., Tierney, T.M., Woolrich, M.W., Stagg, C.J., Barnes, G.R., Bowtell, R., Slater, R., Brookes, M.J., 2019. A tool for functional brain imaging with lifespan compliance. Nat. Commun. 10, 4785. https://doi.org/10.1038/s41467-019-12486-x
4. Iivanainen, J., Stenroos, M., Parkkonen, L., 2017. Measuring MEG closer to the brain: Performance of on-scalp sensor arrays. NeuroImage 147, 542–553. https://doi.org/10.1016/j.neuroimage.2016.12.048