Signal processing in magnetoencephalography.

@article{Vrba2001SignalPI,
  title={Signal processing in magnetoencephalography.},
  author={J. Vrba and S. Robinson},
  journal={Methods},
  year={2001},
  volume={25 2},
  pages={
          249-71
        }
}
The subject of this article is detection of brain magnetic fields, or magnetoencephalography (MEG). The brain fields are many orders of magnitude smaller than the environmental magnetic noise and their measurement represent a significant metrological challenge. The only detectors capable of resolving such small fields and at the same time handling the large dynamic range of the environmental noise are superconducting quantum interference devices (or SQUIDs). The SQUIDs are coupled to the brain… Expand
Tiny Signals from the Human Brain: Acquisition and Processing of Biomagnetic Fields in Magnetoencephalography
TLDR
The prospects of Fourier analysis and wavelet transform in MEG data analysis are referred to, and matching pursuit is suggested as a promising tool for signal decomposition and reconstruction with high resolution in time-frequency plane. Expand
Effective electromagnetic noise cancellation with beamformers and synthetic gradiometry in shielded and partly shielded environments
TLDR
This paper demonstrates that activation of primary somatosensory cortex can be accurately identified using SAM despite the presence of significant stimulus-related magnetic interference, and shows that in a reduced shielding environment the use of higher order synthetic gradiometry is sufficient to obtain signal-to-noise ratios that allow for accurate localisation of cortical sensory function. Expand
Instrumentation for Measuring MEG Signals
TLDR
In the later part of this chapter, atomic magnetometers for future non-cryogenic MEG systems, and brain magnetic resonance based on low-field nuclear magnetic resonance for visualizing brain functional activity are described. Expand
Applications and analysis strategies of magnetoencephalography imaging
TLDR
A new model for the M170 neural generators was developed through the analysis of four different MEG studies, and a novel technique was developed to extend the usage of MEG for magnetic nanoparticle imaging. Expand
Overview of MEG
TLDR
The mapping of spatiotemporal patterns of activity within networks of cortical areas can provide useful information about the functional architecture of the brain related to sensory and cognitive processing, including language, memory, attention, and perception. Expand
Applications of Blind Source Separation to the Magnetoencephalogram Background Activity in Alzheimer’s Disease
In this Doctoral Thesis, Magnetoencephalogram (MEG) background activity from 36 patients with a diagnosis of probable Alzheimer's Disease (AD) and 26 healthy elderly control subjects has beenExpand
A new generation of magnetoencephalography: Room temperature measurements using optically-pumped magnetometers
TLDR
Recording made using a single optically‐pumped magnetometer (OPM) in combination with a 3D‐printed head‐cast designed to accurately locate and orient the sensor relative to brain anatomy highlight the opportunity presented by OPMs to generate uncooled, potentially low‐cost, high SNR MEG systems. Expand
Noninvasive Neurophysiological Imaging with Magnetoencephalography
TLDR
The current chapter will provide a brief historical introduction to MEG and functional magnetic resonance imaging (fMRI), which is the most common method of functional brain imaging, and present some new applications for MEG-based functional brain Imaging. Expand
Novel Noise Reduction Methods
Magnetoencephalography (MEG) is a non-invasive neuroimaging tool that offers a combination of excellent temporal and good spatial resolution, provided that the acquired signals have a high enoughExpand
Novel imaging using a MEG scanner, and MRI homogeneity improvement techniques
The general aims of the work in this thesis are to locate and quantify magnetic dipoles using a Magnetoencephalography (MEG) system based on Superconducting Quantum Interference Device (SQUID)Expand
...
1
2
3
4
5
...

References

SHOWING 1-10 OF 86 REFERENCES
Magnetoencephalography: Detection of the Brain's Electrical Activity with a Superconducting Magnetometer
TLDR
The abnormal MEG, including a measurenment of the direct-current component, suggests that the MEG may yield some information which is new and different from that provided by the EEG. Expand
Squid Gradiometers in Real Environments
TLDR
Noise cancellation by high-order spatial gradiometers is examined in detail, and the gradiometer performance in shielded and unshielded environments is evaluated experimentally using a whole cortex MEG system. Expand
A 122-channel whole-cortex SQUID system for measuring the brain's magnetic fields
A 122-channel neuromagnetometer with a helmet-shaped detector array covering the entire head allows simultaneous recording of magnetic fields over the whole cortex. The instrument has 122 planarExpand
BASELINE OPTIMIZATION FOR NOISE CANCELLATION SYSTEMS
SQUID MEG systems are subjected to environmental noise even when they are operated within shielded rooms [l]. In practice, this noise is usually reduced by means of some noise cancellation method,Expand
Whole cortex, 64 channel SQUID biomagnetometer system
TLDR
Measurements of noise performance and human auditory evoked response in an unshielded industrial environment have largely validated the noise cancellation methods incorporated in the SQUID biomagnetometer system. Expand
Spatial discrimination in SQUID gradiometers and 3rd order gradiometer performance
A detailed description of SQUID gradiometers is presented with the aim of improving their near field detection response while operating in unshielded, magnetically harsh urban environments. SpatialExpand
Magnetoencephalography: Evidence of Magnetic Fields Produced by Alpha-Rhythm Currents
TLDR
Weak alternating magnetic fields outside the human scalp, produced by alpha-rhythm currents, are demonstrated and a course distribution shows left-right symmetry for the particular averaging technique used here. Expand
Advances in Biomagnetism
TLDR
By selecting this architecture, that includes both state-of-the-art hardware concepts and interactive real-time software, a system has been developed that offers the combination of high performance and easy modifiability to the experiment, a contribution to defining the necessary standards for data acquisition and processing in magnetoencephalography is offered. Expand
Localization of brain electrical activity via linearly constrained minimum variance spatial filtering
TLDR
This paper presents a development and analysis of the spatial filtering method for localizing sources of brain electrical activity from surface recordings and explores its sensitivity to deviations between actual and assumed data models. Expand
Functional localization of bilateral auditory cortices using an MRI-linked whole head magnetoencephalography (MEG) system.
TLDR
The whole head MEG is suitable to see small but significant differences of bilateral cerebral function, with exceptionally high spatial resolution, confirmed by the MRI-linked system. Expand
...
1
2
3
4
5
...