Decoding brain signals for spatial orientation from optically-pumped magnetometers

This PhD project aims to leverage Optically Pumped Magnetometers (OPMs), held in a novel lightweight and wearable helmet, to study the neural mechanisms of spatial navigation. Current brain imaging techniques for non-invasive electric signal detection rely on superconducting quantum interference devices (SQUIDs) for magnetoencephalography (MEG), which require a large cryogenic cooling system requiring complete participant stillness. Instead, OPMs offer recording of similar or superior spatiotemporal resolution by utilizing the quantum principles of alkali atoms enabling on-scalp sensor placement and thus increased sensitivity and unprecedented movement during imaging. Therefore we will employ experimental paradigms with an unprecedented degree of real movement during neuroimaging. The goal of this PhD is to identify the neural signatures of the processing of bodily orientation and movement through space, including the representation of movement direction, as dissociated from the well-known representation of head direction. This will include the design and realization of experiments that implement OPMs that facilitate the isolation of the so far hypothesized body direction signals in humans, and bring innovative ways to decode their location in the human brain, in the field of computational neuroscience. Because the representation of allocentric (world-centered) travel direction has not yet been observed in mammals, its magnetoencephalographic profile is unknown, so a novel convolutional neural network (CNN) decoding approach will be implemented, and innovative computational tools will be developed to find the signatures. Because the architecture of CNNs employs generative models of brain signal, it will provide insight into the spatiotemporal features of where specifically in the brain allocentric and egocentric (body-centered) directional information is represented. Because spatial navigation is one of the earliest cognitive functions impaired in Alzheimer's disease, and navigation-related brain regions show the earliest signs of tau neuropathology, a non-invasive OPMs readout of navigational processing could contribute to future non-invasive disease diagnosis and monitoring. This project will therefore bring such innovative quantum technology to the area of clinical diagnosis and non-invasive brain imaging, in particular to the study of the hippocampus, and will bring such technology to low and middle-income countries, by performing experiments that don't require a magnetically shielded room.