Journal: medRxiv

Article Title: Interest of tri-axial rubidium and helium optically pumped magnetometers for on-scalp magnetoencephalography recording of interictal epileptiform discharges

doi: 10.1101/2023.10.02.23296348

Figure Lengend Snippet: Left . Map illustrating the placement of He-OPMs (blue), Rb-OPMs (green) and EEG electrodes (purple edges) with respect to a standard scalp EEG montage. The He-OPM marked with a cross was non-functional during the recording. Right . The OPMs were mounted on a dedicated helmet superimposed on scalp electrodes (not visible).

Article Snippet: The patient underwent 40-minutes of multimodal electrophysiological recording based on four MEG-compatible EEG electrodes (silver Gold EEG disc electrodes, SPES Medica; placed at C4-T4-F8-Cz), five He-OPM prototypes (as described in ( )) and four Rb-OPMs (Gen-3.0, QuSpin Inc.; tri-axial mode, gain 2.7 V/nT; ).

Techniques: Functional Assay

Journal: medRxiv

Article Title: Interest of tri-axial rubidium and helium optically pumped magnetometers for on-scalp magnetoencephalography recording of interictal epileptiform discharges

doi: 10.1101/2023.10.02.23296348

Figure Lengend Snippet: Butterfly plots of 10-second signals of each tangential component, radial component, and virtual component from 4 Rb-OPMs ( Top ) and He-OPMs ( Middle ), after rejection of 11 independent components free of IEDs from the 12-channel raw data. Bipolar plots of 10-second simultaneous signals between each couple of EEG electrodes (placed according to the 10-20 montage) ( Bottom ). All signals were band-pass filtered at 3–38 Hz. This illustrates IEDs that can be detected simultaneously in both kinds of OPM.

Article Snippet: The patient underwent 40-minutes of multimodal electrophysiological recording based on four MEG-compatible EEG electrodes (silver Gold EEG disc electrodes, SPES Medica; placed at C4-T4-F8-Cz), five He-OPM prototypes (as described in ( )) and four Rb-OPMs (Gen-3.0, QuSpin Inc.; tri-axial mode, gain 2.7 V/nT; ).

Techniques:

Journal: medRxiv

Article Title: Interest of tri-axial rubidium and helium optically pumped magnetometers for on-scalp magnetoencephalography recording of interictal epileptiform discharges

doi: 10.1101/2023.10.02.23296348

Figure Lengend Snippet: Top . IED amplitude across three axes, after ICA preprocessing. Tri-axial Rb-OPM with the highest IED amplitude (light grey, left ). Tri-axial He-OPM with the highest IED amplitude (dark grey, right ). Amplitudes correspond to the single ICA component that contained IED activity. Bar plots show mean ± SD across a sample of 102 simultaneous IEDs. The IED amplitude was significantly higher on one tangential axis for the Rb-OPM and on the radial axis for the He-OPM, with respect to the relative position of each kind of OPM to the epileptogenic zone. These differences depending on the measurement axis can be explained by a more optimal position of Rb OPM than He OPM relative to the presumed irritative zone, as supported by the previous clinical EEG data. Bottom . IED amplitude, background activity after ICA preprocessing in the optimal magnetic orientation (virtual sensor). Comparison of each IED amplitude ( left ), background activity from 100 ms to 50 ms before each selected IED peak ( right ) between Rb-OPMs and He-OPMs. All amplitudes correspond to the virtual sensor signal built from the single ICA component that isolated IED activity. The two OPM modalities show similar background noise levels. The higher IED amplitude in Rb-OPM likely reflect difference in OPM positions with respect to the presumed irritative zone localization.

Article Snippet: The patient underwent 40-minutes of multimodal electrophysiological recording based on four MEG-compatible EEG electrodes (silver Gold EEG disc electrodes, SPES Medica; placed at C4-T4-F8-Cz), five He-OPM prototypes (as described in ( )) and four Rb-OPMs (Gen-3.0, QuSpin Inc.; tri-axial mode, gain 2.7 V/nT; ).

Techniques: Activity Assay, Comparison, Isolation