Labyrinthectomy abolishes the behavioral and neural response of rats to a high-strength static magnetic field
Cason AM, Kwon B, Smith JC, Houpt TA.
Department of Biological Science, Program in Neuroscience, The Florida
State University, Tallahassee, Florida 32306-4340, United States.
Vertigo is a commonly-reported side effect of exposure to the high
magnetic fields found in magnetic resonance imaging machines. Although
it has been hypothesized that high magnetic fields interact with the
vestibular apparatus of the inner ear, there has been no direct evidence
establishing its role in magnet-induced vertigo. Our laboratory has
shown that following exposure to high magnetic fields, rats walk in
circles, acquire a conditioned taste aversion (CTA), and express c-Fos
in vestibular and visceral relays of the brainstem, consistent with
vestibular stimulation and vertigo or motion sickness. To determine if
the inner ear is required for these effects, rats were chemically
labyrinthectomized with sodium arsanilate and tested for locomotor
circling, CTA acquisition, and c-Fos induction after exposure within a
14.1 T magnet. Intact rats circled counterclockwise after 30-min
exposure to 14.1 T, but labyrinthectomized rats showed no increase in
circling after magnetic field exposure. After 3 pairings of 0.125%
saccharin with 30-min exposure at 14.1 T, intact rats acquired a
profound CTA that persisted for 14 days of extinction testing;
labyrinthectomized rats, however, did not acquire a CTA and showed a
high preference for saccharin similar to sham-exposed rats. Finally,
significant c-Fos was induced in the brainstem of intact rats by 30-min
exposure to 14.1 T, but magnetic field exposure did not elevate c-Fos in
labyrinthectomized rats above sham-exposed levels. These results
demonstrate that an intact inner ear is necessary for all the observed
effects of exposure to high magnetic fields in rats.
Cason AM, Kwon B, Smith JC, Houpt TA (April 2009). "Labyrinthectomy
abolishes the behavioral and neural response of rats to a high-strength
static magnetic field." Physiology & Behavior 97(1):36-43. PMID: 19419674
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The use of slow-frequency transcranial magnetic stimulation in the
treatment of depression at Brasilia University Hospital: preliminary
Brasil-Neto JP, Boechat-Barros R, da Mota-Silveira DA.
Laboratorio de Neurobiologia, Departamento de Ciencias Fisiologicas, Universidade de Brasilia, Brasilia, DF, Brasil.
This paper reports the use of slow frequency transcranial magnetic
stimulation of the right pre-frontal cortex in three patients with a
diagnosis of major depressive episode according to the DSM-IV
classification. There was a significant improvement in two patients,
with a decrease of over 50% in the Hamilton Scale scores- 17 items.
Possible indications and limitations of this therapeutic tool are
discussed, as well as socio-economic aspects of this new treatment.
Arq Neuropsiquiatr. 2003 Mar;61(1):83-6. Epub 2003 Apr 16.
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Transcranial magnetic stimulation as therapy for depression and other disorders.
Kirkcaldie MT, Pridmore SA, Pascual-Leone A.
Department of Anatomy and Physiology, University of Tasmania, Hobart, Australia.
OBJECTIVE: To provide an overview of the progress and prospects of
transcranial magnetic stimulation as a psychiatric therapy for
METHOD: Published and unpublished studies of the usefulness of
transcranial magnetic stimulation as a therapy for depression were
assessed, and characterised in terms of a consistent measure of dosage.
Additional information was obtained through correspondence, personal
meetings and visits to facilities.
RESULTS: Transcranial magnetic stimulation, a means for inducing
small regional currents in the brain, has been used in clinical
neurology for some time, and can be used on conscious subjects with
minimal side-effects. Early researchers noticed transient mood effects
on people receiving this treatment, which prompted several inconclusive
investigations of its effects on depressed patients. More recently,
knowledge of functional abnormalities associated with depression has led
to trials using repetitive transcranial magnetic stimulation to
stimulate underactive left prefrontal regions, an approach which has
produced short-term benefits for some subjects. The higher dosage
delivered by high-frequency repetitive transcranial magnetic stimulation
appears to produce greater benefits; scope exists for more conclusive
studies based on extended treatment periods.
CONCLUSIONS: Repetitive transcranial magnetic stimulation is a
promising technology. The reviewed evidence indicates that it may be
useful in the treatment of depression, and perhaps other disorders which
are associated with regional hypometabolism. Should repetitive
transcranial magnetic stimulation prove an effective, non-invasive,
drug-free treatment for depression, a range of disorders could be
Aust N Z J Psychiatry. 1997 Apr;31(2):264-72.
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Low-field magnetic stimulation in bipolar depression using an MRI-based stimulator.
Rohan M, Parow A, Stoll AL, Demopulos C, Friedman S, Dager S, Hennen J, Cohen BM, Renshaw PF.
Brain Imaging Center, McLean Hospital, Belmont, MA 02478, USA. email@example.com
OBJECTIVE: Anecdotal reports have suggested mood improvement in
patients with bipolar disorder immediately after they underwent an
echo-planar magnetic resonance spectroscopic imaging (EP-MRSI) procedure
that can be performed within clinical MR system limits. This study
evaluated possible mood improvement associated with this procedure.
METHOD: The mood states of subjects in an ongoing EP-MRSI study of
bipolar disorder were assessed by using the Brief Affect Scale, a
structured mood rating scale, immediately before and after an EP-MRSI
session. Sham EP-MRSI was administered to a comparison group of subjects
with bipolar disorder, and actual EP-MRSI was administered to a
comparison group of healthy subjects. The characteristics of the
electric fields generated by the EP-MRSI scan were analyzed.
RESULTS: Mood improvement was reported by 23 of 30 bipolar disorder
subjects who received the actual EP-MRSI examination, by three of 10
bipolar disorder subjects who received sham EP-MRSI, and by four of 14
healthy comparison subjects who received actual EP-MRSI. Significant
differences in mood improvement were found between the bipolar disorder
subjects who received actual EP-MRSI and those who received sham
EP-MRSI, and, among subjects who received actual EP-MRSI, between the
healthy subjects and the bipolar disorder subjects and to a lesser
extent between the unmedicated bipolar disorder subjects and the bipolar
disorder subjects who were taking medication. The electric fields
generated by the EP-MRSI scan were smaller (0.7 V/m) than fields used in
repetitive transcranial magnetic stimulation (rTMS) treatment of
depression (1-500 V/m) and also extended uniformly throughout the head,
unlike the highly nonuniform fields used in rTMS. The EP-MRSI waveform, a
1-kHz train of monophasic trapezoidal gradient pulses, differed from
that used in rTMS.
CONCLUSIONS: These preliminary data suggest that the EP-MRSI scan
induces electric fields that are associated with reported mood
improvement in subjects with bipolar disorder. The findings are similar
to those for rTMS depression treatments, although the waveform used in
EP-MRSI differs from that used in rTMS. Further investigation of the
mechanism of EP-MRSI is warranted.
Am J Psychiatry. 2004 Jan;161(1):93-8.
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Magnetic fields mimic the behavioral effects of REM sleep deprivation in humans.
Sandyk R, Tsagas N, Anninos PA, Derpapas K.
Democrition University of Thrace, Department of Medical Physics, Greece.
The discovery of rapid eye movement (REM) sleep by Aserinsky and
Kleitman in 1953 initiated the impetus for sleep research and
specifically the investigations of the effects of REM sleep deprivation
(RSD) on animal and human behavior. The behavioral effects of RSD
include the enhancement of motivational and "drive"-related behaviors.
In laboratory animals, RSD has been reported to increase appetite,
sexual behavior, aggressiveness, and locomotor activity. Moreover, RSD
reportedly improves mood in patients with endogenous depression and
heightens appetite and sexual interest in normal subjects. Since
"drive"-related behaviors are thought to involve activation of limbic
dopaminergic reward sites, RSD may enhance motivational behaviors
through an action on limbic dopaminergic functions. In the present
communication, we present two patients (one with multiple sclerosis and
the other with Parkinson's disease) in whom treatment with magnetic
fields produced behavioral effects which paralleled those observed in
REM-sleep-deprived animals and humans. We propose, therefore, that the
behavioral and mental effects of treatment with magnetic fields may be
mediated via RSD and, by inference, involve activation of limbic
dopaminergic reward sites.
Int J Neurosci. 1992 Jul-Aug;65(1-4):61-8.
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Chronic exposure to 2.9 mT, 40 Hz magnetic field reduces melatonin concentrations in humans.
Karasek M, Woldanska-Okonska M, Czernicki J, Zylinska K, Swietoslawski J.
Laboratory of Electron Microscopy, Medical University of Lodz, Poland. Micha.firstname.lastname@example.org
Diurnal rhythm of serum melatonin concentrations was estimated in 12
men with low back pain syndrome before and after exposure to a very
low-frequency magnetic field (2.9 mT, 40 Hz, square wave, bipolar).
Patients were exposed to the magnetic field for 3 weeks (20 min per day,
5 days per week) either in the morning (at 10:00 hr) or in the late
afternoon (at 18:00 hr). Significant depression in nocturnal melatonin
rise was observed regardless of the time of exposure. This phenomenon
was characteristic for all the subjects, although the percent of
inhibition of melatonin secretion varied among the studied individuals.
J Pineal Res. 1998 Dec;25(4):240-4.
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Improvement of right hemispheric functions in a child with Gilles de la Tourette's syndrome by weak electromagnetic fields.
NeuroCommunication Research Laboratories, Danbury, CT 06811, USA.
Gilles de la Tourette's syndrome (GTS) is a chronic, familial
neuropsychiatric disorder of unknown etiology characterized clinically
by the occurrence of motor and vocal tics and by the presence of a
variety of neurobehavioral and neurocognitive abnormalities including
hyperactivity, self-multilatory behavior, obsessive-compulsive behavior,
learning disabilities, and conduct disorder. On the basis of
neuropsychological assessments it has been suggested that GTS is
associated with greater right than left hemispheric dysfunction which
accounts for decrements in visuospatial, visuoconstructional and
visuomotor skills in these patients. Recent case studies have
demonstrated that extracranial application of electromagnetic fields
(EMFs) in the picotesla (pT) range intensity improves visuospatial and
visuoperceptive functions in patients with neurodegenerative disorders
including Parkinson's disease, multiple sclerosis and Alzheimer's
disease. I now present a 6 1/2 year old boy with GTS in whom this
treatment modality produced, in addition to symptomatic behavioral
improvement, also improvement in visuoconstructional and visuomotor
skills as evidenced on various drawing tasks particularly copy of the
Rey-Osterrieth Complex Figure, a task which is especially vulnerable to
right hemispheric functions. These findings suggest that pT range EMFs
may be useful for the treatment of GTS and related disorders and also
reverse some of the cognitive impairments associated with the disease
which are related to right hemispheric dysfunction and which contribute
to learning disabilities in these patients.
Int J Neurosci. 1995 Apr;81(3-4):199-213.
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Effects of magnetic field exposure on open field behaviour and nociceptive responses in mice.
Del Seppia C, Mezzasalma L, Choleris E, Luschi P, Ghione S.
Institute of Clinical Physiology, CNR, via Moruzzi 1, 56124 Pisa, Italy. email@example.com
Results of previous studies have shown that nociceptive sensitivity
in male C57 mice is enhanced by exposure to a regular 37 Hz or an
irregularly varying (<1 Hz) electromagnetic field. In order to test
whether these fields affect more generally mouse behaviour, we placed
Swiss CD-1 mice in a novel environment (open field test) and exposed
them for 2 h to these two different magnetic field conditions. Hence, we
analysed how duration and time course of various behavioural patterns
(i.e. exploration, rear, edge chew, self-groom, sit, walk and sleep) and
nociceptive sensitivity had been affected by such exposure. Nociceptive
sensitivity was significantly greater in magnetically treated mice than
in controls. The overall time spent in exploratory activities was
significantly shorter in both magnetically treated groups (< 1 Hz,
33% and 37 Hz, 29% of total time), than in controls (42%). Conversely,
the time spent in sleeping was markedly longer in the treated groups
(both 27% of total time) than in controls (11%). These results suggest
that exposure to altered magnetic fields induce a more rapid habituation
to a novel environment.
Behav Brain Res. 2003 Sep 15;144(1-2):1-9.
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Biomagnetics: Considerations Relevant to Manned Space Flight, NASA Contract Report CR-889.
Research by Halpern, M. as reported by Busby, D.E.
National Aeronautics and Space Administration, Washington, D.C.
Magnetic field reduction. In an early study to investigate the possible effects of reduced magnetic fields on astronauts as a result of space travel, mice
were kept in mu-metal containers which greatly reduced exposure to the
earth's magnetic field. "In contrast to the normally thriving control[s]
... the mice in the mu-metal cylinders have presented a characteristic,
rather bizarre, picture." "At an early age, large numbers of mu-metal mice have become docile and inactive. Many mice exhibited the highly unusual behavior of lying on their back for prolonged periods of time."
NASA Contract Rep NASA CR. 1967 Nov;:1-57.
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A detailed ethological analysis of the mouse open field test:
effects of diazepam, chlordiazepoxide and an extremely low frequency
pulsed magnetic field.
Choleris E, Thomas AW, Kavaliers M, Prato FS.
Room 9222D, Department of Psychology, Social Science Center,
University of Western Ontario, London, Ontario, Canada N6A 5C2.
The open field test (OFT) is a widely used procedure for examining
the behavioral effects of drugs and anxiety. Detailed ethological
assessments of animal behavior are lacking. Here we present a detailed
ethological assessment of the effects of acute treatment with the
benzodiazepines, diazepam (DZ, 1.5mg/kg) and chlordiazepoxide (CDP, 5.0
and 10.0mg/kg), as well as exposure to a non-pharmacological agent, a
specific pulsed extremely low frequency magnetic field (MAG) on open
field behavior. We examined the duration, frequency and time course of
various behaviors (i.e. exploration, walk, rear, stretch attend, return,
groom, sit, spin turn, jump and sleep) exhibited by male mice in
different regions of a novel open field. Both DZ and CDP consistently
reduced the typical anxiety-like behaviors of stretch attend and
wall-following (thigmotaxis), along with that of an additional new
measure: 'returns', without producing any overall effects on total
locomotion. The drugs also differed in their effects. CDP elicited a
shift in the locomotor pattern from a 'high explore' to a 'high walk',
while DZ mainly elicited alterations in sit and groom. The MAG treatment
was repeated twice with both exposures reducing horizontal and vertical
(rearing) activity and increasing grooming and spin turns. However, the
anxiety-like behaviors of stretch attend and return were marginally
reduced by only the first exposure. We conclude that a detailed
ethological analysis of the OFT allows not only the detection of
specific effects of drugs and non-pharmacological agents (i.e. pulsed
magnetic field) on anxiety-like behaviors, but also permits the
examination of non-specific effects, in particular those on general
Neurosci Biobehav Rev. 2001 May;25(3):235-60.
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A subterranean mammal uses the magnetic compass for path integration
Kimchi T, Etienne AS, Terkel J.
*Department of Zoology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel.
Path integration allows animals to navigate without landmarks by
continuously processing signals generated through locomotion. Insects
such as bees and ants have evolved an accurate path integration system,
assessing and coding rotations with the help of a general directional
reference, the sun azimuth. In mammals, by contrast, this process can
take place through purely idiothetic (mainly proprioceptive and
vestibular) signals. However, without any stable external reference for
measuring direction, path integration is highly affected by cumulative
errors and thus has been considered so far as valid only for
short-distance navigation. Here we show through two path integration
experiments (homing and shortcut finding) that the blind mole rat
assesses direction both through internal signals and by estimating its
heading in relation to the earth's magnetic field. Further, it is shown
that the greater the circumvolution and length of the traveled path, the
more the animal relies on the geomagnetic field. This path integration
system strongly reduces the accumulation of errors due to inaccuracies
in the estimation of rotations and thus allows the mole rat to navigate
efficiently in darkness, without the help of any landmark, over both
short and long distances.
Proc Natl Acad Sci U S A. 2004 Jan 19.
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Rapporteur report: weak field interactions in the central nervous system.
National Radiological Protection Board, Chilton, Didcot, Oxfordshire, UK. firstname.lastname@example.org
Experimental evidence was presented of the interaction of extremely
low frequency (ELF) physiologically weak electric fields (that is,
internal fields of around 1-1000 mV m(-1)) with tissues of the central
nervous system and the consequences of this for visual and cognitive
function. These internal fields are higher than those induced in the
body by exposure to environmental EMFs, but are small compared to nerve
excitation thresholds. Two papers considered the effect of weak electric
fields directly applied to hippocampal tissue in vitro on neuronal
excitability assessed from evoked responses and on the modulation of
neural network activity involving large numbers of individual neurons. A
review was presented of the effects on electrical measures of
perceptual and cognitive processes and on the performance of various
behavioural tasks in volunteers exposed to electromagnetic fields.
Finally, two papers addressed the visual perception of flickering
light--phosphenes--in volunteers exposed to ELF magnetic fields. The
first examined possible physiological origins of this phenomenon and the
second assessed the induced electric fields and currents in the retina,
using complex dosimetric modelling. These papers were discussed in
several plenary sessions and in one breakout group, all of which are
briefly summarized in this report.
Radiat Prot Dosimetry. 2003; 106(4): 357-61.
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Experimental facilitation of the sensed presence: possible
intercalation between the hemispheres induced by complex magnetic
Persinger MA, Healey F.
Behavioral Neuroscience Program, Department of Psychology, Laurentian University, Sudbury, Ontario P3E 2C6.
This experiment was designed to test the hypothesis that the sensed
presence, the feeling of a proximal sentient being, can be evoked within
the laboratory. Under double-blind conditions, 48 university men and
women were exposed to weak (100 nT to 1 muT), complex, pulsed magnetic
fields that were applied primarily over the right temporoparietal
region, primarily over the left temporoparietal region, or equally
across both hemispheres (one treatment per group) for 20 minutes while
wearing opaque goggles in a very quiet room. A fourth group was exposed
to a sham-field condition. Subjects who received greater stimulation
over the right hemisphere or equal stimulation across both hemispheres
reported more frequent incidences of presences, fears, and odd smells
than did the subjects who received greater stimulation over the left
hemisphere or who were exposed to the sham-field condition. The results
suggest that the sensed presence is subject to experimental
manipulation. This experimental procedure could be employed to explore
the idea that the experience of a sensed presence is a resident property
of the human brain and may be the fundamental source for phenomena
attributed to visitations by gods, spirits, and other ephemeral
J Nerv Ment Dis. 2002 Aug;190(8):533-41.
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Electromagnetic field of mobile phones affects visual event related potential in patients with narcolepsy.
Jech R, Sonka K, Ruzicka E, Nebuzelsky A, Bohm J, Juklickova M, Nevsimalova S.
Department of Neurology, 1st Medical Faculty, Charles University, Prague, Czech Republic. email@example.com
The effects of the mobile phone (MP) electromagnetic fields on
electroencephalography (EEG) and event-related potentials (ERP) were
examined. With regard to the reported effects of MP on sleep, 22
patients with narcolepsy-cataplexy were exposed or sham exposed for 45
min to the MP (900 MHz, specific absorption rate 0.06 W/kg) placed close
to the right ear in a double blind study. There were no changes of the
EEG recorded after the MP exposure. A subgroup of 17 patients was
studied on visual ERP recorded during the MP exposure. Using an adapted
"odd-ball" paradigm, each patient was instructed to strike a key
whenever rare target stimuli were presented. There were three variants
of target stimuli (horizontal stripes in (i) left, (ii) right hemifields
or (iii) whole field of the screen). The exposure enhanced the
positivity of the ERP endogenous complex solely in response to target
stimuli in the right hemifield of the screen (P < 0.01). The reaction
time was shortened by 20 ms in response to all target stimuli (P <
0.05). In conclusion, the electromagnetic field of MP may suppress the
excessive sleepiness and improve performance while solving a monotonous
cognitive task requiring sustained attention and vigilance. Copyright
2001 Wiley-Liss, Inc.
Bioelectromagnetics. 2001 Oct;22(7):519-28.
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Changes in brain memory functions as affected by a constant magnetic field.
Konovalov VF, Serikov IS.
Institute of Cell Biophysics, Russian Academy of Sciences, Pushchino.
Effects of CMF on memory processes in adult volunteers (non-sleep vs
hypnotic condition) has been studied at laboratory and clinical
conditions. The results point out that CMF changes the interhemispheric
relations and result in memory malfunction. The malfunction of memory
activity in volunteers after action of CMF was influenced by two
factors: magnetic field position under different brain areas and
functional status of volunteers: awake or hypnotic.
Radiats Biol Radioecol. 1998 Sep-Oct;38(5):769-74.
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