Non-Invasive Functional-Brain-Imaging with an OPM-based Magnetoencephalography System.

Amir Borna,Julia M Stephen,Michael Weisend,Jim Mckay,Peter D D Schwindt,Samu Taulu,Anthony P Colombo,Tony R Carter,Yuan-Yu Jau,Christos Papadelis

doi:10.1371/journal.pone.0227684

Abstract

A non-invasive functional-brain-imaging system based on optically-pumped-magnetometers (OPM) is presented. The OPM-based magnetoencephalography (MEG) system features 20 OPM channels conforming to the subject’s scalp. We have conducted two MEG experiments on three subjects: assessment of somatosensory evoked magnetic field (SEF) and auditory evoked magnetic field (AEF) using our OPM-based MEG system and a commercial MEG system based on superconducting quantum interference devices (SQUIDs). We cross validated the robustness of our system by calculating the distance between the location of the equivalent current dipole (ECD) yielded by our OPM-based MEG system and the ECD location calculated by the commercial SQUID-based MEG system. We achieved sub-centimeter accuracy for both SEF and AEF responses in all three subjects. Due to the proximity (12 mm) of the OPM channels to the scalp, it is anticipated that future OPM-based MEG systems will offer enhanced spatial resolution as they will capture finer spatial features compared to traditional MEG systems employing SQUIDs.

Highlights

Direct, non-invasive measurement of the human brain relies on sensing either the electric potential, electroencephalography (EEG), or magnetic field, magnetoencephalography (MEG) [1], or a combination of both [2]
We report on the development of a 20-channel Optically pumped magnetometers (OPMs)-based magnetoencephalography system to study complex neural circuits, non-invasively, in human subjects
The MEG experiments were conducted with the same protocols using a 306-channel Elekta-Neuromag superconducting quantum interference devices (SQUIDs) system (Elekta, Sweden) located in a magnetically shielded room (MSR) at the Mind Research Network (Albuquerque, NM)

Summary

Introduction

Non-invasive measurement of the human brain relies on sensing either the electric potential, electroencephalography (EEG), or magnetic field, magnetoencephalography (MEG) [1], or a combination of both [2]. These electromagnetic fields are mainly caused by neuronal current sources in the cerebral cortex [1, 3], and finding the precise location, orientation, and strength of these neuronal current sources with high spatiotemporal resolution remains a high priority for non-invasive functional brain imaging. Dr Michael Weisend, currently with StimScience, has decades of experience in electrophysiological data analysis and system design. Dr Weisend has conducted MEG data analysis of SQUID-based MEG system

Methods

Results

Discussion

Conclusion