The spatial resolution of magnetoencephalography (MEG) can be increased from that conventional SQUID-based systems by employing on-scalp sensor arrays e.g. optically-pumped magnetometers (OPMs). However, OPMs reach sufficient sensitivity for neuromagnetic measurements only when operated in a very low absolute magnetic field few nanoteslas or less, usually not reached typical magnetically shielded room constructed MEG. Moreover, drifts affect the calibration OPMs. Static and dynamic...

Electrophysiological signals recorded intracranially show rich frequency content spanning from near-DC to hundreds of hertz. Noninvasive electromagnetic measured with electroencephalography (EEG) or magnetoencephalography (MEG) typically contain less signal power in high frequencies than invasive recordings. Particularly, noninvasive detection gamma-band activity (>30 Hz) is challenging since coherently active source areas are small at such and the available imaging methods have limited...

Abstract To estimate the neural generators of magnetoencephalographic (MEG) signals, MEG data have to be co-registered with an anatomical image, typically MR image. Optically-pumped magnetometers (OPMs) enable construction on-scalp systems providing higher sensitivity and spatial resolution than conventional SQUID-based systems. We present a co-registration method that can applied systems, regardless number sensors. apply structured-light scanner create surface mesh subject’s head sensor...

Recent advances in magnetic sensing has made on-scalp magnetoencephalography (MEG) possible. In particular, optically-pumped magnetometers (OPMs) have reached sensitivity levels that enable their use MEG. contrast to the SQUID sensors used current MEG systems, OPMs do not require cryogenic cooling and can thus be placed within millimetres from head, enabling construction of sensor arrays conform shape an individual's head. To properly estimate location neural sources brain, one must...

We introduce two Convolutional Neural Network (CNN) classifiers optimized for inferring brain states from magnetoencephalographic (MEG) measurements. design follows a generative model of the electromagnetic (EEG and MEG) signals allowing explorative analysis neural sources informing classification. The proposed networks outperform traditional as well more complex when decoding evoked induced responses to different stimuli across subjects. Importantly, these models can successfully generalize...

Surface currents provide a general way to model static magnetic fields in source-free volumes. To facilitate the use of surface magneto-quasistatic problems, we have implemented set computational tools Python package named bfieldtools. In this work, describe physical and principles toolset. be able work with arbitrary shape, discretize on triangle meshes using piecewise-linear stream functions. We apply analytical discretizations integral equations obtain field potentials associated discrete...

We present a novel open-source Python software package, bfieldtools, for magneto-quasistatic calculations with current densities on surfaces of arbitrary shape. The core functionality the relies stream-function representation surface-current density and its discretization triangle mesh. Although this technique is well-known in certain fields, to date related implementations have not been published or limited specific applications. With we aimed produce general, easy-to-use well-documented...

Atomic spin sensors offer precision measurements using compact microfabricated packages, placing them in a competitive position for both market and research applications. The performance of these sensors, such as the dynamic range, may be enhanced through magnetic field control. In this work, we discuss design miniature coils three-dimensional localized control by direct placement around sensor, flexible alternative to global approaches used previously. Coils are designed on biplanar...

In this paper, we analyze spatial sampling of electro- (EEG) and magnetoencephalography (MEG), where the electric or magnetic field is typically sampled on a curved surface such as scalp. By simulating fields originating from representative adult-male head, study spatial-frequency content in EEG well on- off-scalp MEG. This analysis suggests that on-scalp MEG, MEG can benefit up to 280, 90 110 samples, respectively. addition, suggest new approach obtain sensor locations are optimal with...

In this paper, we propose a method to estimate the position, orientation, and gain of magnetic field sensor using set (large) electromagnetic coils. We apply for calibrating an array optically pumped magnetometers (OPMs) magnetoencephalography (MEG). first measure fields coils at multiple known positions well-calibrated triaxial magnetometer, model these discreetly sampled vector spherical harmonics (VSH) functions. then localize calibrate OPM by minimizing sum squared errors between signals...

The human prefrontal cortex (PFC) has been shown to be important for metacognition, the capacity monitor and control one's own cognitive processes. Here we dissected neural architecture of somatosensory metacognition using navigated single-pulse transcranial magnetic stimulation (TMS) modulate tactile working memory (WM) processing. We asked subjects perform WM tasks give a confidence rating their performance after each trial. circumvented challenge interindividual variability in functional...

Abstract The spatial resolution of magnetoencephalography (MEG) can be increased from that conventional SQUID-based systems by employing on-scalp sensor arrays e.g. optically-pumped magnetometers (OPMs). However, OPMs reach sufficient sensitivity for neuromagnetic measurements only when operated in a very low absolute magnetic field few nanoteslas or less, usually not reached typical magnetically shielded room constructed MEG. Moreover, drifts affect the calibration OPMs. Static and dynamic...

Thermal motion of charge carriers in a conducting object causes magnetic field noise that may interfere with sensitive measurements near the object. In this paper, we describe method to compute spectral properties thermal from arbitrarily shaped thin objects. The is based on modeling divergence-free currents surface using stream function and calculating magnetically independent noise-current modes. By doing this, obtain power density as well its spatial correlations frequency dependence. We...

In this paper, we analyze spatial sampling of electro- (EEG) magnetoencephalography (MEG), where the electric or magnetic field is typically sampled on a curved surface such as scalp. Using simulated measurements, study spatial-frequency content in EEG well on- and off-scalp MEG. The analysis suggests that on-scalp MEG would generally benefit from three times more samples than Based theory Gaussian processes experimental design, suggest an approach to obtain locations surfaces are optimal...

Abstract Electrophysiological signals recorded intracranially show rich frequency content spanning from near-DC to hundreds of hertz. Noninvasive electromagnetic measured with electroencephalography (EEG) or magnetoencephalography (MEG) typically contain less signal power in high frequencies than invasive recordings. Particularly, noninvasive detection gamma-band activity (> 30 Hz) is challenging since coherently active source areas are small at such and the available imaging methods have...

Abstract Recent advances in magnetic sensing has made on-scalp magnetoencephalography (MEG) possible. In particular, optically-pumped magnetometers (OPMs) have reached sensitivity levels that enable their use MEG. contrast to the SQUID sensors used current MEG systems, OPMs do not require cryogenic cooling and can thus be placed within millimetres from head, enabling construction of sensor arrays conform shape an individual’s head. To properly estimate location neural sources brain, one must...

Objective: To estimate the neural current distribution underlying magnetoencephalographic (MEG) signals and to link such estimates brain anatomy, MEG data have be co-registered with an anatomical image, typically MR image. Optically-pumped magnetometers (OPMs) enable construction of on-scalp systems providing higher sensitivity spatial resolution than conventional SQUID-based systems. Here, we present a co-registration method that can applied systems, regardless number channels. Methods: We...

We present a theoretical framework for analyzing spatial sampling of fields in three-dimensional space. The bridges Shannon's and information theory to Bayesian probabilistic inference experimental design. Based on the theory, we an approach optimal curved surfaces analyze EEG as well that on- off-scalp MEG. Our spatial-frequency analysis simulated measurements shows available degrees freedom electric potential are limited by smoothing due head tissues, while those magnetic field measurement...

We describe micro-fabricated rubidium vapor cells with integrated temperature-control functionality and demonstrate their suitability for use in miniaturized ultra-sensitive magnetometers. These functionalized (FVCs) embody a dual-chamber design low-conductivity silicon anti-permeation coatings micro-structured thin-film platinum surface traces as resistive heaters temperature sensors. Thermal tests show our ability to control alkali metal distribution within the FVCs, ensuring clean sensing...