Moving magnetoencephalography towards real-world applications with a wearable system

Abstract

SummaryImaging human brain function with techniques such as magnetoencephalography1 (MEG) typically requires a subject to perform tasks whilst their head remains still within a restrictive scanner. This artificial environment makes the technique inaccessible to many people, and limits the experimental questions that can be addressed. For example, it has been difficult to apply neuroimaging to investigation of the neural substrates of cognitive development in babies and children, or in adult studies that require unconstrained head movement (e.g. spatial navigation). Here, we develop a new type of MEG system that can be worn like a helmet, allowing free and natural movement during scanning. This is possible due to the integration of new quantum sensors2,3 that do not rely on superconducting technology, with a novel system for nulling background magnetic fields. We demonstrate human electrophysiological measurement at millisecond resolution whilst subjects make natural movements, including head nodding, stretching, drinking and playing a ball game. Results compare well to the current state-of-the-art, even when subjects make large head movements. The system opens up new possibilities for scanning any subject or patient group, with myriad applications such as characterisation of the neurodevelopmental connectome, imaging subjects moving naturally in a virtual environment, and understanding the pathophysiology of movement disorders.

Using optically pumped magnetometers to measure magnetoencephalographic signals in the human cerebellum

“…By applying this method, the dominant components of the static field and field gradient can be diminished by factors of 46 and 13, respectively, in a volume of 40 × 40 × 40 cm 3 encapsulating the head (Boto et al . ; Holmes et al . ).…”

“…The OP‐MEG system has been previously described in detail (Boto et al . , ; Holmes et al . ; Tierney et al .…”

“…We have recently built such a wearable OP‐MEG system, placing the sensors close to the scalp by mounting them in a 3D printed cast based on the individual's head MR imaging (Boto et al . , ). The use of a 3D‐printed cast can accurately inform sensor positions and orientations with respect to the brain anatomy, thus facilitating accurate source imaging.…”

“…Besides, this system is less susceptible to muscle artefacts compared to EEG (Boto et al . ). These characteristics combined allow non‐invasive mapping of human electrophysiology when subjects interact with the real world and even move freely (Boto et al .…”

“…These characteristics combined allow non‐invasive mapping of human electrophysiology when subjects interact with the real world and even move freely (Boto et al . ), thus making OP‐MEG an ideal candidate for the study of cerebellar electrophysiology of both motor and non‐motor tasks.…”