Helium optically pumped magnetometers can detect epileptic abnormalities as well as SQUIDs as shown by intracerebral recordings.

SQUID-based magnetoencephalography has been shown to improve the diagnosis and surgical treatment decision for presurgical evaluation of drug-resistant epilepsy. Still, its use remains limited due to several constraints such as cost, fixed helmet size and obligation of immobility. A new generation of sensors, the optically pumped magnetometers (OPMs), could overcome these limitations. In this study, we validate the ability of Helium-based OPM ( 4 He-OPM) sensors to record epileptic brain activity thanks to simultaneous recordings with intracerebral EEG (stereotactic EEG, SEEG). We recorded simultaneous SQUIDs-SEEG and 4He-OPM-SEEG signals in one patient during two sessions. We show that epileptic activities on intracerebral EEG can be recorded by OPMs with a better signal-to noise ratio than classical SQUIDs. The OPM sensors open new venues for the widespread application of magnetoencephalography in the management of epilepsy and other neurological diseases and fundamental neuroscience. Significance Statement We performed a simultaneous recording of Helium-based Optically Pumped Magnetometers (OPM) and intracerebral EEG and validate for the first time OPM results with signals recorded directly within the brain. We demonstrate that epileptic abnormalities seen on intracerebral electrodes are detected by OPMs with a better signal-to noise ratio than classical magnetoencephalography. This represents a significant step towards the validation of OPM-based recordings for epilepsy diagnosis and for clinical and neuroscience research.