Magneto-encefalografie

1996 ◽  
Vol 8 (3) ◽  
pp. 64-70
Author(s):  
M.J. Peters ◽  
F. Reinders
Keyword(s):  
Magnetic Field ◽  
Epileptic Focus ◽  
Current Dipole ◽  
Non Invasive ◽  
Active Population ◽  
Presurgical Mapping ◽  
The Brain ◽  
Weak Fields ◽  
The Magnetic Field ◽  
Realistic Shape

SummaryA magnetoencephalogram (MEG) is the registration of the magnetic field in points near the head. Because MEG's are weak fields, they have to be measured by means of superconducting sensors. The electric active population of neurons can be computed from the distribution of the magnetic field at a certain instant of time. This is called the inverse problem. In order to solve this probem, both the generators and the head have to be modelled. Usually, a patch of active neurons is modelled as a current dipole. Commonly, the head is described by three compartments, representing the brain, the skull and the scalp. The compartments may have the shape of spheres or they may have a realistic shape. Integration of EEG and MEG with MRI leads to a technique for functional imaging of the brain with a time resolution of one millisecond and a spatial resolution of one centimetre. Clinical applications are the non-invasive localization of an epileptic focus or the presurgical mapping of the sensorimotor cortex.

scholarly journals Less Is Enough: Assessment of the Random Sampling Method for the Analysis of Magnetoencephalography (MEG) Data

2019 ◽  
Vol 24 (4) ◽  
pp. 98
Author(s):  
Cristina Campi ◽  
Annalisa Pascarella ◽  
Francesca Pitolli
Keyword(s):  
Magnetic Field ◽  
Random Sampling ◽  
Sampling Method ◽  
Brain Activity ◽  
Memory Storage ◽  
Non Invasive ◽  
Regularization Techniques ◽  
Ill Posed ◽  
The Brain ◽  
The Magnetic Field

Magnetoencephalography (MEG) aims at reconstructing the unknown neuroelectric activity in the brain from non-invasive measurements of the magnetic field induced by neural sources. The solution of this ill-posed, ill-conditioned inverse problem is usually dealt with using regularization techniques that are often time-consuming, and computationally and memory storage demanding. In this paper we analyze how a slimmer procedure, random sampling, affects the estimation of the brain activity generated by both synthetic and real sources.

scholarly journals MEG as a Medical Diagnostic Tool in the Greek Population

2015 ◽  
Vol 58 (3) ◽  
pp. 71-78 ◽  
Author(s):  
Photios Anninos ◽  
Adam Adamopoulos ◽  
Athanasia Kotini
Keyword(s):  
Research Work ◽  
Research Field ◽  
Greek Population ◽  
Brain Disorders ◽  
Important Research ◽  
Non Invasive ◽  
Medical Diagnostic ◽  
Invasive Method ◽  
The Brain ◽  
The Magnetic Field

Magnetoencephalography (MEG) is the recording of the magnetic field produced by the flowing of ions in the brain. This article reports our experience in the application of MEG in patients and healthy volunteers in the Greek population. We provide a brief description of our research work. The MEG data were recorded in a magnetically shielded room with a whole-head 122 channel or an one-channel biomagnetometer. Our results lead us to believe that the MEG is an important research field which is evolving quickly with a number of interesting findings with respect to normal and abnormal functions of the human brain. It could provide clinical practice with an easy to perform non invasive method, which could be adjunct to conventional methods for the evaluation of brain disorders.

Two Realizations of the Wearable PPG Sensor Working in Reflectance Mode for Measurement in Weak Magnetic Field

2021 ◽  
Vol 10 (1) ◽  
pp. 55
Author(s):  
Jiří Přibil ◽  
Anna Přibilová ◽  
Ivan Frollo
Keyword(s):  
Magnetic Field ◽  
Weak Magnetic Field ◽  
Wearable Sensors ◽  
Control Device ◽  
Wireless Transmission ◽  
Electromagnetic Disturbance ◽  
Non Invasive ◽  
Field Environment ◽  
Scanning Area ◽  
The Magnetic Field

The paper describes and compares properties of two realizations of wearable sensors based on the photoplethysmography (PPG) principle for non-invasive acquisition of the human heart rate. The designed sensors enable measurement of the PPG signal in the magnetic field environment with the inherent radiofrequency and electromagnetic disturbance. They can monitor the stress of a tested person during examination in the scanning area of the open-air magnetic resonance tomograph. The performed auxiliary experiments verify the practical functionality of both developed sensors including real-time wireless transmission of the measured PPG signal samples to the control device for further analysis and processing.

scholarly journals The Effect of The Shape of Magnetic Field on the Viability of Endothelial Cells

2021 ◽  
Author(s):  
Akram Mahna ◽  
Saeed Solali ◽  
Fateme Akbarbeiglou
Keyword(s):  
Magnetic Field ◽  
Endothelial Cells ◽  
Magnetic Fields ◽  
Chronic Exposure ◽  
Umbilical Vein ◽  
Non Invasive ◽  
Effective Factor ◽  
Umbilical Vein Endothelial Cells ◽  
Acute And Chronic Exposure ◽  
The Magnetic Field

Purpose: Magnetic field is one of the effective and non-invasive modalities on biology and angiogenesis. Studies on the effects of magnetic fields on angiogenesis showed that the shape of the magnetic field could potentially affect angiogenesis. Therefore, this study aimed to control the frequency, intensity, and duration of exposure of magnetic field while investigating the effect of the shape of the magnetic field on the viability of Human Umbilical Vein Endothelial Cells (HUVECs). Materials and Methods: The HUVECs were exposed to various shapes of 50 and 60 Hz magnetic fields with intensities of 0.5 and 1 mT in acute and chronic exposure regimes. The viability of HUVECs was assessed via MTT assay. Results: Results showed that the sin type 50 and 60 Hz magnetic fields are more effective in decreasing the viability. The rectified 100 and 120 Hz with 1 and 0.5 mT could increase and decrease the viability compared with 50 and 60 Hz, respectively. Conclusion: It can be concluded that the shape of the magnetic field can be an effective factor in biology and must be controlled to have a reliable response.

The Influence Of The Torso On The Magnetic Field Of A Current Dipole

Biomagnetism ◽  
1981 ◽  
pp. 337-342
Author(s):  
Maria J. Peters ◽  
A.P. van de Graaf ◽  
A. van Oosterom
Keyword(s):  
Magnetic Field ◽  
Current Dipole ◽  
The Magnetic Field ◽  
A Current

scholarly journals Effects of Moderate Static Magnetic Field on Neural Systems Is a Non-invasive Mechanical Stimulation of the Brain Possible Theoretically?

2020 ◽  
Vol 14 ◽  
Author(s):  
Antonio Hernando ◽  
Fernando Galvez ◽  
Miguel A. García ◽  
Vanesa Soto-León ◽  
Carlos Alonso-Bonilla ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Static Magnetic Field ◽  
Mechanical Stimulation ◽  
Neural Systems ◽  
Non Invasive ◽  
The Brain ◽  
Stimulation Of

scholarly journals BIOFEEDBACK IN THE MAGNETIC FIELD (ON STEREOTOPOGRAPHY OF COGNITIVE FUNCTIONS)

2013 ◽  
Vol 12 (2) ◽  
pp. 7-20 ◽  
Author(s):  
K. G. Mazhirina ◽  
M. A. Pokrovskiy ◽  
M. V. Rezakova ◽  
A. A. Savelov ◽  
A. A. Sokolov ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Self Regulation ◽  
Imitation Game ◽  
Middle Temporal ◽  
The Real ◽  
Cortical Areas ◽  
On Line ◽  
The Brain ◽  
The Magnetic Field ◽  
Qualitative Characteristics

The brain was mapped on-line using fMRI technology in the process of the development of self-regulation skills. We studied the dynamics of new neural networks being created in the real and simulated biofeedback models. It was shown that immersion in a virtual story brings about the large involvement of cortical areas, which are characterized by high values of voxels in the middle-temporal, occipital and frontal regions. We discuss the qualitative characteristics of the real and the imitation game periods.

Magnetography: A novel Characterization Tool for Li-Ion-Batteries

2013 ◽  
Vol 1544 ◽  
Author(s):  
Timm Bergholz ◽  
Theodor Nuñez ◽  
Jürgen Wackerl ◽  
Carsten Korte ◽  
Detlef Stolten
Keyword(s):  
Magnetic Field ◽  
Normal Operation ◽  
Additional Parameter ◽  
Battery Management ◽  
Li Ion Batteries ◽  
Non Invasive ◽  
Spatially Resolved ◽  
Standardized Measurement ◽  
Li Ion ◽  
The Magnetic Field

ABSTRACTThe application of magnetography as a novel method to determine the state of charge (SoC) of commercial Li-ion Batteries is reported. The method is non-invasive and nondestructive and suitable to be applied during normal operation. It is based on spatially resolved measurement of the magnetic field B, induced by the changing current flow during cycling. A standardized measurement setup and procedure for conventional AMR-sensors has been developed, offering high reproducibility (∼0.1%) and the chance to characterize the different spatial components of the magnetic field (Bx, By, Bz). The percentage deviation of the B-distributions for different SoCs for a given current load reveals significant differences. A change of B of up to 20% between SoCs of 90% and 10% is found. The influence of current density at different SoC reveals a constant magnetic susceptibility χ at low SoC and a field dependent χ at high SoC. Both effects are attributed to the change of the magnetic properties upon varying the amount of intercalated lithium in the transition metal (LixNi1/3Co1/3Mn1/3O2) based intercalation cathode. The method can be used to provide an additional parameter for SoCestimation to battery management systems.

scholarly journals Self-Propelled Janus Microdimer Swimmers under a Rotating Magnetic Field

Nanomaterials ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1672 ◽  
Author(s):  
Shimin Yu ◽  
Ningze Ma ◽  
Hao Yu ◽  
Haoran Sun ◽  
Xiaocong Chang ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Rotating Magnetic Field ◽  
Robotic Systems ◽  
Maximum Speed ◽  
Complex Environments ◽  
Field Frequency ◽  
Practical Applications ◽  
Non Invasive ◽  
Remote Actuation ◽  
The Magnetic Field

Recent strides in micro- and nanofabrication technology have enabled researchers to design and develop new micro- and nanorobots for biomedicine and environmental monitoring. Due to its non-invasive remote actuation and convenient navigation abilities, magnetic propulsion has been widely used in micro- and nanoscale robotic systems. In this article, a highly efficient Janus microdimer swimmer propelled by a rotating uniform magnetic field was investigated experimentally and numerically. The velocity of the Janus microdimer swimmer can be modulated by adjusting the magnetic field frequency with a maximum speed of 133 μm·s−1 (≈13.3 body length s−1) at the frequency of 32 Hz. Fast and accurate navigation of these Janus microdimer swimmers in complex environments and near obstacles was also demonstrated. This efficient propulsion behavior of the new Janus microdimer swimmer holds considerable promise for diverse future practical applications ranging from nanoscale manipulation and assembly to nanomedicine.

Sign in / Sign up

Export Citation Format

Share Document