scholarly journals Recording brain activities in unshielded Earth’s field with optically pumped atomic magnetometers

2020 ◽  
Vol 6 (24) ◽  
pp. eaba8792 ◽  
Author(s):  
Rui Zhang ◽  
Wei Xiao ◽  
Yudong Ding ◽  
Yulong Feng ◽  
Xiang Peng ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Medical Diagnosis ◽  
Alpha Rhythm ◽  
Brain Activity ◽  
High Sensitivity ◽  
Noninvasive Method ◽  
Optically Pumped ◽  
Field Noise ◽  
The Relationship ◽  
The Brain

Understanding the relationship between brain activity and specific mental function is important for medical diagnosis of brain symptoms, such as epilepsy. Magnetoencephalography (MEG), which uses an array of high-sensitivity magnetometers to record magnetic field signals generated from neural currents occurring naturally in the brain, is a noninvasive method for locating the brain activities. The MEG is normally performed in a magnetically shielded room. Here, we introduce an unshielded MEG system based on optically pumped atomic magnetometers. We build an atomic magnetic gradiometer, together with feedback methods, to reduce the environment magnetic field noise. We successfully observe the alpha rhythm signals related to closed eyes and clear auditory evoked field signals in unshielded Earth’s field. Combined with improvements in the miniaturization of the atomic magnetometer, our method is promising to realize a practical wearable and movable unshielded MEG system and bring new insights into medical diagnosis of brain symptoms.

Neurodevelopment in the first three years: implications for child development, professional practice and policy

2014 ◽  
Vol 9 (2) ◽  
pp. 154-164 ◽  
Author(s):  
Danya Glaser
Keyword(s):  
Brain Development ◽  
Brain Activity ◽  
Brain Maturation ◽  
Policy And Practice ◽  
Content Type ◽  
Key Issues ◽  
And Function ◽  
The Relationship ◽  
The Brain ◽  
Brain Connections

Purpose – The purpose of this paper is to outline brain structure and development, the relationship between environment and brain development and implications for practice. Design/methodology/approach – The paper is based on a selected review of the literature and clinical experience. Findings – While genetics determine the sequence of brain maturation, the nature of brain development and functioning is determined by the young child's caregiving environment, to which the developing brain constantly adapts. The absence of input during sensitive periods may lead to later reduced functioning. There is an undoubted immediate equivalence between every mind function – emotion, cognition, behaviour and brain activity, although the precise location of this in the brain is only very partially determinable, since brain connections and function are extremely complex. Originality/value – This paper provides an overview of key issues in neurodevelopment relating to the development of young children, and implications for policy and practice.

Mortal Body, Immortal Mind

2012 ◽  
Vol 17 (1) ◽  
pp. 5-26
Author(s):  
Hans Goller
Keyword(s):  
Brain Activity ◽  
The Body ◽  
Activity Data ◽  
Brain Functions ◽  
Body Experiences ◽  
Research Findings ◽  
The Relationship ◽  
Near Death Experiences ◽  
The Brain ◽  
Alternative Theories

Neuroscientists keep telling us that the brain produces consciousness and consciousness does not survive brain death because it ceases when brain activity ceases. Research findings on near-death-experiences during cardiac arrest contradict this widely held conviction. They raise perplexing questions with regard to our current understanding of the relationship between consciousness and brain functions. Reports on veridical perceptions during out-of-body experiences suggest that consciousness may be experienced independently of a functioning brain and that self-consciousness may continue even after the termination of brain activity. Data on studies of near-death-experiences could be an incentive to develop alternative theories of the body-mind relation as seen in contemporary neuroscience.

scholarly journals Estimation of the Directions of Alpha Rhythm Elementary Sources Using the Method of Human Brain Functional Tomography Based On the Magnetic Encephalography Data

2018 ◽  
Vol 13 (2) ◽  
pp. 426-436 ◽  
Author(s):  
M.N. Ustinin ◽  
S.D. Rykunov ◽  
A.I. Boyko ◽  
O.A. Maslova ◽  
K.D. Walton ◽  
...  
Keyword(s):  
Inverse Problem ◽  
Time Series ◽  
Human Brain ◽  
Alpha Rhythm ◽  
Brain Activity ◽  
Problem Solution ◽  
New York University ◽  
Magnetic Encephalography ◽  
The Brain ◽  
Calculation Grid

New method for the magnetic encephalography data analysis was proposed. The method transforms multichannel time series into the spatial structure of the human brain activity. In this paper we further develop this method to determine the dominant direction of the electrical sources of brain activity at each node of the calculation grid. We have considered the experimental data, obtained with three 275-channel magnetic encephalographs in New York University, McGill University and Montreal University. The human alpha rhythm phenomenon was selected as a model object. Magnetic encephalograms of the brain spontaneous activity were registered for 5-7 minutes in magnetically shielded room. Detailed multichannel spectra were obtained by the Fourier transform of the whole time series. For all spectral components, the inverse problem was solved in elementary current dipole model and the functional structure of the brain activity was calculated in the frequency band 8-12 Hz. In order to estimate the local activity direction, at the each node of calculation grid the vector of the inverse problem solution was selected, having the maximal spectral power. So, the 3D-map of the brain activity vector field was produced – the directional functional tomogram. Such maps were generated for 15 subjects and some common patterns were revealed in the directions of the alpha rhythm elementary sources. The proposed method can be used to study the local properties of the brain activity in any spectral band and in any brain compartment.

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 No Detectable Electroencephalographic Activity After Clinical Declaration of Death Among Tibetan Buddhist Meditators in Apparent Tukdam, a Putative Postmortem Meditation State

2021 ◽  
Vol 11 ◽  
Author(s):  
Dylan T. Lott ◽  
Tenzin Yeshi ◽  
N. Norchung ◽  
Sonam Dolma ◽  
Nyima Tsering ◽  
...  
Keyword(s):  
Brain Activity ◽  
Auditory Brainstem ◽  
Tibetan Buddhist ◽  
University Of Wisconsin ◽  
Brainstem Response ◽  
The University ◽  
Electroencephalographic Activity ◽  
The Relationship ◽  
The Brain ◽  
Early Postmortem

Recent EEG studies on the early postmortem interval that suggest the persistence of electrophysiological coherence and connectivity in the brain of animals and humans reinforce the need for further investigation of the relationship between the brain’s activity and the dying process. Neuroscience is now in a position to empirically evaluate the extended process of dying and, more specifically, to investigate the possibility of brain activity following the cessation of cardiac and respiratory function. Under the direction of the Center for Healthy Minds at the University of Wisconsin-Madison, research was conducted in India on a postmortem meditative state cultivated by some Tibetan Buddhist practitioners in which decomposition is putatively delayed. For all healthy baseline (HB) and postmortem (PM) subjects presented here, we collected resting state electroencephalographic data, mismatch negativity (MMN), and auditory brainstem response (ABR). In this study, we present HB data to demonstrate the feasibility of a sparse electrode EEG configuration to capture well-defined ERP waveforms from living subjects under very challenging field conditions. While living subjects displayed well-defined MMN and ABR responses, no recognizable EEG waveforms were discernable in any of the tukdam cases.

HTc dc SQUID Magnetometers

2000 ◽  
Vol 14 (25n27) ◽  
pp. 3086-3091
Author(s):  
E. SARNELLI ◽  
G. TESTA ◽  
C. CAMERLINGO ◽  
M. RUSSO ◽  
S. PAGANO
Keyword(s):  
Magnetic Field ◽  
High Sensitivity ◽  
Corner Frequency ◽  
Junction Type ◽  
Field Noise ◽  
Field Modulation ◽  
Readout Scheme ◽  
Geometrical Dimensions ◽  
Good Agreement ◽  
Squid Magnetometers

High sensitivity HTc dc-SQUID magnetometers, of bicrystal junction type, have been designed, fabricated and characterized. The magnetometers are characterized by a direct-coupling planar design and their parameters and geometrical dimensions have been optimized in order to achieve the lowest possible noise level. The IV characteristics are RSJ-like and show no excess current. The measured SQUID normalized inductances and magnetic field modulation periods are in good agreement with the expected values. The magnetic field noise spectral densities, measured with a flux locked loop electronic setup, exhibit typical white noise levels of about 150 fT/Hz 1/2 at frequencies above 2 KHz. At lower frequencies a 1/f noise is observed. By employing a bias-reversal electronic readout scheme, the 1/f corner frequency can be reduced to values less than 100 Hz.

Induced Theta Activity as a Biomarker for a Morbid Effect of Alcoholism on the Brain in Long-Term Abstinent Alcoholics

2013 ◽  
Vol 27 (2) ◽  
pp. 76-83 ◽  
Author(s):  
Casey S. Gilmore ◽  
George Fein
Keyword(s):  
Brain Function ◽  
Target Stimulus ◽  
Brain Activity ◽  
Theta Activity ◽  
Theta Oscillations ◽  
Time Frequency ◽  
Related Information ◽  
The Relationship ◽  
The Brain

Event-related, target stimulus-phase-locked (evoked) brain activity in both the time and time-frequency (TF) domains (the P3b ERP; evoked theta oscillations) has been shown to be reduced in alcoholics. Recently, studies have suggested that there is alcohol-related information in the non-stimulus-phase-locked (induced) theta TF activity. We applied TF analysis to target stimulus event-related EEG recorded during an oddball task from 41 long-term abstinent alcoholics (LTAA) and 74 nonalcoholic controls (NAC) to investigate the relationship between P3b, evoked theta, and induced theta activity. Results showed that an event-related synchronization (ERS) of induced theta (1) was larger in LTAA compared to NAC, and (2) was sensitive to differences between LTAA and NAC groups that was independent of the differences accounted for by P3b amplitude or evoked theta. These findings suggest that increased induced theta ERS may likely be a biomarker for a morbid effect of alcohol abuse on brain function.

Magnetic Field Mapping and Biaxial Vector Operation for Biomagnetic Applications Using High-Sensitivity Optically Pumped Atomic Magnetometers

2011 ◽  
Vol 50 ◽  
pp. 116604 ◽  
Author(s):  
Shuji Taue ◽  
Yasuyuki Sugihara ◽  
Tetsuo Kobayashi ◽  
Kiyoshi Ishikawa ◽  
Keigo Kamada
Keyword(s):  
Magnetic Field ◽  
High Sensitivity ◽  
Optically Pumped ◽  
Field Mapping ◽  
Vector Operation ◽  
Magnetic Field Mapping

Non‐oriented cesium sensors for airborne magnetometry and gradiometry

Geophysics ◽  
1984 ◽  
Vol 49 (11) ◽  
pp. 2024-2031 ◽  
Author(s):  
C. D. Hardwick
Keyword(s):  
Magnetic Field ◽  
National Research Council ◽  
Larmor Frequency ◽  
High Sensitivity ◽  
Field Vector ◽  
Error Characteristic ◽  
Optically Pumped ◽  
Optimal Angle ◽  
Multiple Sensor ◽  
The Magnetic Field

Optically pumped magnetometers are characterized by an optimal angle between their optical axes and the direction of the magnetic field they are sensing. Departure from the optimal angle causes a shift in the Larmor frequency with a corresponding error in the scalar value of the magnetic field being measured. To minimize this error, magnetometers are conventionally either mounted in multiple sensor clusters such that the errors tend to cancel, or they are mechanically oriented to maintain the optimal angle with respect to the magnetic field vector. Recent cesium vapor magnetometers using a split‐beam technique have a sufficiently flat error characteristic that they can be flown in a non‐oriented or “strap‐down” configuration. This configuration has advantages with respect to conventional methods in terms of reduced size and weight and of greatly reduced cost. This paper describes two fixed orientations for a particular split‐beam magnetometer and calculates the allowable maneuver envelope for all dip angles from 0 to 90 degrees. It is shown that the residual orientation errors can best be handled by the conventional type of magnetic interference compensation model that must, in any case, be implemented in digital form for high‐sensitivity magnetometry or for any type of gradiometry. The National Aeronautical Establishment (NAE) of the National Research Council of Canada has flown strap‐down magnetometers in a three‐axis gradiometer array in a Convair 580 for several years. Results for the entire normal maneuver envelope of the aircraft, including 30 degree bank turns, have equalled or surpassed those obtained with oriented magnetometers. Several typical maneuver compensation results are presented that gave root‐mean‐square (rms) (one‐sigma) residual errors as low as 0.03 gammas (γ) for total field and 3.5 mgammas/m (mγ/m) for lateral gradient.

scholarly journals High Sensitivity Optically Pumped Quantum Magnetometer

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Valentina Tiporlini ◽  
Kamal Alameh
Keyword(s):  
Magnetic Field ◽  
Pump Power ◽  
Optimal Design ◽  
Optical Pumping ◽  
High Sensitivity ◽  
Optically Pumped ◽  
Optical Pump ◽  
Operation Temperature ◽  
Quantum Magnetometer ◽  
Sinusoidal Magnetic Field

Quantum magnetometers based on optical pumping can achieve sensitivity as high as what SQUID-based devices can attain. In this paper, we discuss the principle of operation and the optimal design of an optically pumped quantum magnetometer. The ultimate intrinsic sensitivity is calculated showing that optimal performance of the magnetometer is attained with an optical pump power of 20 μW and an operation temperature of 48°C. Results show that the ultimate intrinsic sensitivity of the quantum magnetometer that can be achieved is 327 fT/Hz1/2over a bandwidth of 26 Hz and that this sensitivity drops to 130 pT/Hz1/2in the presence of environmental noise. The quantum magnetometer is shown to be capable of detecting a sinusoidal magnetic field of amplitude as low as 15 pT oscillating at 25 Hz.

Sign in / Sign up

Export Citation Format

Share Document