Fig. 4

Simulated MEG helmet designs for a 2-year-old. Main figures show normalised representation of measurable signal across the brain. (Specifically a 1 nAm source dipole has been simulated at all cortical locations and we measured the Frobenius norm of the resulting sensor-level field pattern. These values were normalised by the average Frobenius norm when sensors are placed on the scalp surface—i.e. the values, which mostly scale between 0 and 1, represent signal quality relative to the bespoke helmet). Inset figures show the location of simulated MEG sensors. a Bespoke helmet. b Helmet to fit 95% of 2-year-olds. c Modified bike helmet. d Cryogenic MEG system. e Distribution of measurable signal values, across all dipole locations for each helmet type