Abstract:
:The aim of this study was to determine a current density threshold for exciting the motor cortex area of the brain. The current density threshold for excitation of nerve fibres (20 microm in diameter) found in the literature is approximately 1 A/m(2) at frequencies lower than 1 kHz. In consideration of a safety factor of 100, the International Commission on Non-Ionizing Radiation Protection (ICNIRP) recommends to restrict the exposure to 0.01 A/m(2). The electromagnetic stimulation of neurons in the motor cortex is used in the clinical diagnosis of nerve lesions and neuropathy by means of magnetic or electrical transcranial stimulation. Combining medical data from clinical studies and technical specifications of the Magstim Model 200 stimulator, we were able to compute the current density threshold for the excitation of the human motor cortex by means of the finite element method (FEM). A 3D-CAD head model was built on the basis of magnetic resonance imaging (MRI) slices and segmented into four anatomical structures (scalp, skull, brain, and ventricular system) with different conductivities. A current density threshold for the stimulation of the motor cortex area of the upper limbs of 6 and 2.5 A/m(2) at 2.44 kHz and 50 Hz, respectively, was calculated. As these values lie above the recommended ICNIRP values by two orders of magnitude there is no need for lower safety standards with regard to stimulation of the brain.
journal_name
Bioelectromagneticsjournal_title
Bioelectromagneticsauthors
Kowalski T,Silny J,Buchner Hdoi
10.1002/bem.10036subject
Has Abstractpub_date
2002-09-01 00:00:00pages
421-8issue
6eissn
0197-8462issn
1521-186Xjournal_volume
23pub_type
杂志文章abstract::Some numerical and analytical methods used to estimate the internal electric fields and current densities produced within human and animal models by low-frequency electric and magnetic fields are surveyed. A major goal of such modeling is the design of laboratory experiments on cellular systems or animal models to pro...
journal_title:Bioelectromagnetics
pub_type: 杂志文章,评审
doi:10.1002/bem.2250130705
更新日期:1992-01-01 00:00:00
abstract::Magnetic fields (60 Hz) of 1.5 and 80 microT caused a significant reduction in the weight of Drosophila melanogaster. Moreover, fruit flies in an 80 microT field showed lower developmental stability than either those in a 0 or 1.5 microT field. Developmental instability was measured by fluctuating asymmetry and freque...
journal_title:Bioelectromagnetics
pub_type: 杂志文章
doi:
更新日期:2000-09-01 00:00:00
abstract::The possible effects of repeated night-time exposure to an extremely low frequency magnetic field (ELF-MF) on melatonin were investigated in nine healthy male subjects aged 23-37 yr. The 16-week experiment consisted of 3 weeks of pre-exposure, 11 weeks of night-time exposure to MF generated from a nonheated electric s...
journal_title:Bioelectromagnetics
pub_type: 杂志文章
doi:10.1002/1521-186x(200102)22:2<138::aid-bem1017>3.0
更新日期:2001-02-01 00:00:00
abstract::An automated blood sampling system was developed for use with tethered baboons (Papio cynocephalus) during concurrent exposure to 60 Hz 30 kV/m electric fields and 0.1 mT (1.0 G) magnetic fields. The system was controlled by a FORTH-based microcomputer, which operated a pump, a fraction collector, and two pinch valves...
journal_title:Bioelectromagnetics
pub_type: 杂志文章
doi:10.1002/bem.2250160710
更新日期:1995-01-01 00:00:00
abstract::The MobilEe-study was the first cross-sectional population-based study to investigate possible health effects of mobile communication networks on children using personal dosimetry. Exposure was assessed every second resulting in 86,400 measurements over 24 h for each participant. Therefore, a functional approach to an...
journal_title:Bioelectromagnetics
pub_type: 杂志文章
doi:10.1002/bem.20477
更新日期:2009-05-01 00:00:00
abstract::In order to demonstrate possible specific effects of microwaves at the cellular level V-79 Chinese hamster cells were exposed to 2.45-GHz radiation at power levels of 20-200 mW/cm2 and at specific absorption rates of 10-100 mW/g. Intracellular cytoplasmic changes were observed by fluorescence polarization using a meth...
journal_title:Bioelectromagnetics
pub_type: 杂志文章
doi:10.1002/bem.2250050212
更新日期:1984-01-01 00:00:00
abstract::We have previously reported that the exposure to an abnormal magnetic field simulating the one encountered by the International Space Station (ISS) orbiting around the Earth may enhance autonomic response to emotional stimuli. Here we report the results of the second part of that study which tested whether this field ...
journal_title:Bioelectromagnetics
pub_type: 杂志文章
doi:10.1002/bem.20438
更新日期:2009-01-01 00:00:00
abstract::The extent of electromagnetic interference (EMI) from 16.7-Hz alternate current power lines in the human surface electrocardiogram (ECG) was evaluated. Results showed a direct linear correlation between mean EMI and magnetic induction of 5.8-21 microT on a railroad platform (electric field: 270 V/m). EMI inside a rail...
journal_title:Bioelectromagnetics
pub_type: 杂志文章
doi:10.1002/bem.20319
更新日期:2007-07-01 00:00:00
abstract::Blackman et al. [1994] describe an experiment that purports to show that weak 45 Hz magnetic fields inhibit the growth of neurites from PC-12 cells treated with a growth stimulation factor. I present a statistical analysis of the data in that paper that shows that the data were corrupted in some way; hence, the result...
journal_title:Bioelectromagnetics
pub_type: 评论,杂志文章
doi:10.1002/(SICI)1521-186X(1996)17:6<510::AID-BEM12>3
更新日期:1996-01-01 00:00:00
abstract::This study was undertaken to investigate whether power frequency magnetic fields can affect the kinetics of cell cycle progression in exposed human cells. To achieve this, cultures of normal human fibroblasts were synchronised in the G(0) phase of the cell cycle and exposed to 50 Hz magnetic fields at a range of flux ...
journal_title:Bioelectromagnetics
pub_type: 杂志文章
doi:
更新日期:1999-10-01 00:00:00
abstract::Several investigators have reported robust, statistically significant results that indicate that weak (approximately 1 microT) magnetic fields (MFs) increase the rate of morphological abnormalities in chick embryos. However, other investigators have reported that weak MFs do not appear to affect embryo morphology at a...
journal_title:Bioelectromagnetics
pub_type: 杂志文章
doi:10.1002/(sici)1521-186x(1997)18:6<431::aid-bem5>3.
更新日期:1997-01-01 00:00:00
abstract::Using a crossover experimental design, we evaluated our earlier findings that exposure to a 30 kV/m, 60 Hz electric field for 12 hours per day, 7 days per week for 6 weeks produced significant changes in the performance rates of social behaviors among young adult male baboons. In the crossover experiment, the former c...
journal_title:Bioelectromagnetics
pub_type: 杂志文章
doi:10.1002/bem.2250130506
更新日期:1992-01-01 00:00:00
abstract::An attempt has been made to understand whether 50 Hz electric and magnetic fields (EMFs) are involved in producing bioeffects by exposing human erythrocytes in vitro. The study evaluated some key glycolytic enzymes, glucose consumption, lactate production, energy charge, 2,3-diphosphoglycerate, and reduced glutathione...
journal_title:Bioelectromagnetics
pub_type: 杂志文章
doi:10.1002/bem.2250140410
更新日期:1993-01-01 00:00:00
abstract::Serial longitudinal and transverse sections were prepared from roots of Cucumis sativus and Cucurbita maxima that had been exposed/sham-exposed to 60-Hz electric fields for 0-2 days. Field exposures were selected to produce a 10-20% or a 70-80% growth inhibition in whole roots of both species. Cortical cell length and...
journal_title:Bioelectromagnetics
pub_type: 杂志文章
doi:10.1002/bem.2250080108
更新日期:1987-01-01 00:00:00
abstract::Magnetic resonance (MR)-based electrical impedance tomography (MREIT) is a widely used imaging technique that provides high-resolution conductivity images at DC or below the 1 kHz frequency range. Using an MR scanner, this technique injects imaging currents into the human body and measures induced internal magnetic fl...
journal_title:Bioelectromagnetics
pub_type: 杂志文章
doi:10.1002/bem.21852
更新日期:2014-07-01 00:00:00
abstract::Research conducted over the past 5 years has addressed the hypothesis that the reported association between residential magnetic fields and childhood leukemia may be explained by exposure to contact current. The use of multi-grounded neutrals in electrical distribution and residential electrical wiring systems in the ...
journal_title:Bioelectromagnetics
pub_type: 杂志文章,评审
doi:10.1002/bem.20126
更新日期:2005-01-01 00:00:00
abstract::We used exposure to microwaves from a global system for mobile communication (GSM) mobile phone (915 MHz, specific absorption rate (SAR) 37 mW/kg) and power frequency magnetic field (50 Hz, 15 muT peak value) to investigate the response of lymphocytes from healthy subjects and from persons reporting hypersensitivity t...
journal_title:Bioelectromagnetics
pub_type: 临床试验,杂志文章
doi:10.1002/bem.20103
更新日期:2005-04-01 00:00:00
abstract::Exposure systems that provide good magnetic field uniformity, minimum stray fields, and minimal heating, vibration, and hum, as well as capability for true sham exposure in which current flows in the coils, are needed to determine rigorously the biological effects of weak magnetic fields. Designs based on acrylic poly...
journal_title:Bioelectromagnetics
pub_type: 杂志文章
doi:10.1002/bem.2250150610
更新日期:1994-01-01 00:00:00
abstract::A new human head phantom has been proposed by CENELEC/IEEE, based on a large scale anthropometric survey. This phantom is compared to a homogeneous Generic Head Phantom and three high resolution anatomical head models with respect to specific absorption rate (SAR) assessment. The head phantoms are exposed to the radia...
journal_title:Bioelectromagnetics
pub_type: 杂志文章
doi:10.1002/bem.20088
更新日期:2005-02-01 00:00:00
abstract::In a previous investigation we reported that exposure to a moderate (300 mT) static magnetic field (SMF) causes transient DNA damage and promotes mitochondrial biogenesis in human umbilical vein endothelial cells (HUVECs). To better understand the response of HUVECs to the 300 mT SMF, a high-quality subtracted cDNA li...
journal_title:Bioelectromagnetics
pub_type: 杂志文章
doi:10.1002/bem.20686
更新日期:2012-01-01 00:00:00
abstract::This study examined the time dependence effects of exposure to radiofrequency radiation (RFR) emitted by standard GSM cellular phones on the cognitive functions of humans. A total of 48 healthy right-handed male subjects performed a spatial working memory task (that required either a left-hand or a right-hand response...
journal_title:Bioelectromagnetics
pub_type: 杂志文章
doi:10.1002/bem.20458
更新日期:2009-04-01 00:00:00
abstract::Cytostatic-induced polyneuropathy (CIPN) is a common and serious toxicity in tumor patients. Treatment and prophylactic measures are mainly ineffective. Therefore, there is an urgent need to establish a sufficient therapy for pPNP. Between July 2007 and August 2008, 20 patients were treated with low frequency (4-12 Hz...
journal_title:Bioelectromagnetics
pub_type: 信件
doi:10.1002/bem.21897
更新日期:2015-04-01 00:00:00
abstract::The present analysis was stimulated by previous findings on the possible influence of natural ultralow-frequency (ULF; 0.001-10 Hz) geomagnetic field variations on the cardiovascular system and indications of an effect of man-made ULF magnetic fields on the rate of myocardial infarction. In the present study, we consi...
journal_title:Bioelectromagnetics
pub_type: 杂志文章
doi:10.1002/(SICI)1521-186X(1996)17:6<436::AID-BEM2>3.
更新日期:1996-01-01 00:00:00
abstract::There is growing public concern that radio frequency electromagnetic fields may have adverse biological effects. In the present study eight healthy male students were tested to see whether or not radio frequency electromagnetic fields as used in modern digital wireless telecommunication (GSM standard) have noticeable ...
journal_title:Bioelectromagnetics
pub_type: 临床试验,杂志文章,随机对照试验
doi:10.1002/bem.51
更新日期:2001-05-01 00:00:00
abstract::The electromagnetic exposure of cell phone users depends on several parameters. One of the most dominant of these is the distance between the cell phone and the head tissue. The pinna can be regarded as a spacer between the top of the phone and the head tissue. The size of this spacer has not yet been systematically s...
journal_title:Bioelectromagnetics
pub_type: 杂志文章
doi:10.1002/bem.20575
更新日期:2010-07-01 00:00:00
abstract::Specific absorption rate (SAR) value is dependent on permittivity value. However, variability in the published permittivity values for human and animal tissue and the development of sophisticated 3-dimensional digital anatomical models to predict SAR values has resulted in the need to understand how model parameters (...
journal_title:Bioelectromagnetics
pub_type: 杂志文章
doi:10.1002/bem.66
更新日期:2001-09-01 00:00:00
abstract::Rat PC12 pheochromocytoma cells have been treated with nerve growth factor and then exposed to athermal levels of a packet-modulated radiofrequency field at 836.55 MHz. This signal was produced by a prototype time-domain multiple-access (TDMA) transmitter that conforms to the North American digital cellular telephone ...
journal_title:Bioelectromagnetics
pub_type: 杂志文章
doi:10.1002/(sici)1521-186x(1997)18:3<223::aid-bem4>3.
更新日期:1997-01-01 00:00:00
abstract::In this work we tested viability, proliferation, and vulnerability of neural cells, after continuous radiofrequency (RF) electromagnetic fields exposure (global system for mobile telecommunications (GSM) modulated 900 MHz signal at a specific absorption rate (SAR) of 1 W/kg and maximum duration 144 h) generated by tra...
journal_title:Bioelectromagnetics
pub_type: 杂志文章
doi:10.1002/bem.20507
更新日期:2009-10-01 00:00:00
abstract::Published and new data for grounded humans, swine, and rats exposed to vertical, 60-Hz electric fields are used to determine field strengths at the surfaces of the bodies and average components of induced-current density along the axes of the bodies. At the tops of the bodies, surface electric fields are increased (en...
journal_title:Bioelectromagnetics
pub_type: 杂志文章
doi:10.1002/bem.2250010203
更新日期:1980-01-01 00:00:00
abstract::The use of electronic article surveillance (EAS) systems has become popular in many public sites. As a consequence, concern has risen about infant exposure to magnetic fields (MFs) from this kind of device. To evaluate infant exposure to MFs of an EAS system (operating at 125 kHz and 13.56 MHz), we numerically compare...
journal_title:Bioelectromagnetics
pub_type: 杂志文章
doi:10.1002/bem.21901
更新日期:2015-04-01 00:00:00