Concurrent spinal and brain imaging with optically pumped magnetometers

Abstract

The spinal cord and its interactions with the brain are fundamental for movement control and somatosensation. However, brain and spinal cord electrophysiology in humans have largely been treated as distinct enterprises, in part due to the relative inaccessibility of the spinal cord. Consequently, there is a dearth of knowledge on human spinal electrophysiology, including the multiple pathologies of the central nervous system that affect the spinal cord as well as the brain. Here we exploit recent advances in the development of wearable optically pumped magnetometers (OPMs) which can be flexibly arranged to provide coverage of both the spinal cord and the brain concurrently in unconstrained environments. Our system for magnetospinoencephalography (MSEG) measures both spinal and cortical signals simultaneously by employing a custom-made spinal scanning cast. We evidence the utility of such a system by recording simultaneous spinal and cortical evoked responses to median nerve stimulation, demonstrating the novel ability for concurrent non-invasive millisecond imaging of brain and spinal cord.

Magnetoencephalography with optically pumped magnetometers (OPM-MEG): the next generation of functional neuroimaging

“…Arrays can be designed to target specific brain regions with high sensor density, for example, if high spatial resolution is desired in a specific area (recently published examples include the language network [19], hippocampus [20], and cerebellum [21]). It is also becoming apparent that OPM use is not limited to the brain, with arrays also having been used to measure electrophysiological signals in the muscles [22], peripheral nerves [23], spinal cord [24], retina [25], and the foetus [26]. Another advantage is that, whereas SQUIDs typically measure the magnetic field in one orientation (usually radial to the A participant sits with their head in a static helmet (see inset photo, adapted from [16]), containing an array of field sensors (blue circles).…”

Recent developments and future avenues for human corticospinal neuroimaging

“…Additionally, we firmly believe that open science practices (i.e., data sharing, code sharing) will foster the development of corticospinal fMRI methods and analysis. Crucially, while we have focused on fMRI in this review, there are other non-invasive neuroimaging techniques such as magnetospinography (MSG) ( Curio et al, 1991 ; Sumiya et al, 2017 ; Sakaki et al, 2020 ; Akaza et al, 2021 ; Hashimoto et al, 2022 ; Mardell et al, 2022 ) based on super-conducting quantum interference devices (SQUIDs) and non-invasive electrospinography (ESG) ( Liberson et al, 1966 ; Cracco, 1972 , 1973 ; Matthews et al, 1974 ; Jones, 1977 ). Similar to corticospinal fMRI, MSG is technically demanding.…”

Combining Magnetoencephalography with Telemetric Streaming of Intracranial Recordings and Deep Brain Stimulation – a Feasibility Study

“…Using OPMs for study of monopolar DBS effects could be particularly promising, particularly when one is interested in a limited frequency range and can render this range artefact-free by adjusting the stimulation frequency and the sampling rate. OPM systems are also currently being refined for recordings during naturalistic movement and flexible sensor placement to access areas which are challenging for cryogenic MEG such as hippocampus ( Tierney, Levy, et al, 2021), cerebellum ( Lin et al, 2019), and spinal cord ( Mardell et al, 2022). Moreover, new types of OPM sensors are still being developed which might have even better properties in terms of noise floor, bandwidth, and resilience to external interference ( Gutteling et al, 2023;Kowalczyk et al, 2021).…”