From: Terry W. Colvin (fortean1@mindspring.com)
Date: Wed May 22 2002 - 11:52:39 MDT
Note to MC, MCTECH, and EWAR list members: my comments regarding
Prof. McFadden's paper were based on a poorly written, misleading press
release. The original paper, which I learned today from McFadden is
available on the Net at
< http://www.surrey.ac.uk/qe/PDFs/cemi_theory_paper.pdf >, offers more
cogent support for his assertions and if very relevant to the concerns of
these lists.
If Adair (see below) and McFadden are right -- and we need to examine
their conclusions skeptically -- we need to rethink some basic premises,
since these scientists assert that there are much lower exogenous
(outside-the-brain) EM effects on neural processes than previously
assumed on these lists.
In a response (below) to my email, Prof. McFadden cites research (also
cited in the paper) that appears to support his (counterintuitive) assertion
that "skin, skull and cerebrospinal fluid shield us from external electric
fields (McFadden's comments are shown in red throughout my message
below):
"A 60 Hz electrical field of 1000 V/m (typical of a powerline) will
generate a tissue field of only 40 mV/m inside the head (Adair, 1991),
clearly much weaker than either the endogenous em field or the field
caused by thermal noise in cell membranes."
The key question here is the validity of Yale physics professor Robert
Adair's landmark paper ("Adair,R.K. (1991). Constraints on biological
effects of weak extremely-low-frequency electromagnetic fields.
Physical Review A 43, 1039-1048.), which dismisses health effects of
power lines and other sources of EM radiation.
Bioelectromagnetic Hygienist Marjorie Lundquist offers a rebuttal to
Adair in this paper:
< http://216.239.39.100/search?q=cache:eMbTwJkTXWwC:www.niehs.nih.gov/
emfrapid/html/EMF_DIR_RPT/Dir_Comments/CD_Files/VOL3/emf3_103.pdf
+adair+%22Physical+Review%22+%22Constraints+on+biological+effects%
22&hl=en&ie=UTF8 >
And Wired News cites some skeptical views by scientists regarding
McFadden's theory in Consciousness Based on Wireless?,
< http://wired.com/news/technology/0,1282,52674,00.html >
Here is Prof. McFadden's reply, unedited (his comments in red):
-----Original Message-----
From: Johnjoe McFadden [mailto:j.mcfadden@surrey.ac.uk]
Sent: Tuesday, May 21, 2002 6:40 AM
To: west; Mc@Topica. Com; mctech; Ewar@Topica. Com
Cc: press-office; s.pockett
Subj: Re: Our Conscious Mind Could Be An Electromagnetic Field
original message From: Wes Thomas
To: Mc@Topica. Com ; mctech@topica.com ; Ewar@Topica. Com
Cc: press-office@surrey.ac.uk ; s.pockett@auckland.ac.nz ;
j.mcfadden@surrey.ac.uk
Sent: Tuesday, May 21, 2002 6:52 AM
Subj: Our Conscious Mind Could Be An Electromagnetic Field
This sounds like an interesting and credible hypothesis ... until you get to
the following statement (below): "One of the objections to an
electromagnetic field theory of consciousness is, if our minds are
electromagnetic, then why don't we pass out when we walk under an
electrical cable or any other source of external electromagnetic fields?
The answer is that our skin, skull and cerebrospinal fluid shield us from
external electric fields."
This of course is complete nonsense. Electromagnetic radiation from 50
or 60 Hz electrical cables is predominantly from the magnetic
component, not the electric
*****
which is why the article specifies "external electric fields". if you read
the full paper publsihed in Journal of Consciousness Studies (available on
my website at < http://www.surrey.ac.uk/qe > ) you will see I deal with this
issue in some detail:
"The high conductivity of the cerebral fluid and fluid within the brain
ventricles creates an effective ‘Faraday cage’ that insulates the brain
from most natural exogenous electric fields. A constant external
electric field will thereby induce almost no field at all in the brain
(Adair, 1991). Alternating currents from technological devices (power
lines, mobile phones, etc.) will generate an alternating induced field, but
its magnitude will be very weak. For example, a 60 Hz electrical field of
1000 V/m (typical of a powerline) will generate a tissue field of only 40
mV/m inside the head (Adair, 1991), clearly much weaker than either the
endogenous em field or the field caused by thermal noise in cell
membranes. Magnetic fields do penetrate tissue much more readily than
electric fields but most naturally encountered magnetic fields, and also
those experienced during nuclear magnetic resonance (NMR) scanning,
are static (changing only the direction of moving charges) and are
thereby unlikely to have physiological effects. Changing magnetic fields
will penetrate the skull and induce electric currents in the brain.
However, there is abundant evidence (from e.g. TMS studies as outlined
above,) that these do modify brain activity. Indeed, repetitive TMS is
subject to strict safety guidelines to prevent inducing seizures in normal
subjects (Hallett, 2000) through field effects. "
-- magnetic fields cannot be blocked except by rare alloys, such as mu
metal; and even at high frequencies (where the electric component
predominates), EM radiation is only weakly attenuated by body tissues.
You expect that kind of nonsense from the psychobabble-prone Journal
of Consciousness Studies but not from the distinguished University of
Surrey.
This issue has been addressed by several researchers who have clearly
shown that external EM fields with specific pulse, power, and frequency
characteristics strongly affect the brain and consciousness. For
example: Allan Frey (Human Auditory System Response
To Modulated Electromagnetic Energy, J. Appl. Physiol. 17(4): 689-692. 1962,
< http://www.raven1.net/frey.htm >) and Michael Persinger (Richards, P.M.,
Persinger, M.A. and Koren, S.A. (1993). "Modification of activation and
evaluation properties of narratives by weak complex magnetic field
patterns that simulate limbic burst firing." International Journal of
Neuroscience, 71: 71-85; Richards, P.M., Koren, S.A. and Persinger, M.A.
(1992). "Experimental stimulation by burst-firing weak magnetic fields
over the right temporal lobe may facilitate apprehension in women."
Perceptual and Motor Skills, 75: 667-670; Gillis, C. and Persinger, M.A.
(1993). "Shifts in the Plutchik emotion profile indices following three
weekly treatments with pulsed vs. continuous cerebral magnetic fields."
Perceptual and Motor Skills, 76: 168-170; Persinger, M.A. (1993).
"Geophysical variables and behavior: LXXI. Differential contribution of
geomagnetic activity to paranormal experiences concerning death and
crisis; an alternative to the ESP hypothesis." Perceptual and Motor
Skills, 76: 555-562).
*********
Again, I deal with this much more fully in the paper:
"In humans, the strongest evidence for the sensitivity of the brain to
relatively weak em fields comes from the therapeutic use of
transcranial magnetic stimulation (TMS). In TMS, a current passing
through a coil placed on the scalp of subjects is used to generate a
time-varying magnetic field that penetrates the skull and induces an
electrical field in neuronal tissue. The precise mechanism by which TMS
modulates brain activity is currently unclear but is generally assumed to
be through electrical induction of local currents in brain tissue that
modulate nerve firing patterns. TMS has been shown to generate a
range of cognitive disturbances in subjects including: modification of
reaction time, induction of phosphenes, suppression of visual perception,
speech arrest, disturbances of eye movements and mood changes
(Hallett, 2000). Even single TMS pulses have been shown to induce
spreading changes to the brain’s electrical activity, that can be detected
by EEG or MEG and persists for many milliseconds after stimulation
(Ilmoniemi et al., 1997; Ilmoniemi et al., 1999), once again indicating that
neuronal firing patterns have been modulated. The field induced in
cortical tissue by TMS cannot be measured directly but may be
estimated from modelling studies. The evoked field depends critically on
the instrumentation, particularly the coil geometry and strength and
frequency of stimulating magnetic field. In one study where stimulation
utilised a set of four coils, the induced electrical field was estimated to
be in the range of 50 – 130 V/m (Epstein et al., 1990). Another modelling
study with a figure of eight coil estimated fields of 20 - 150 V/m
(Ruohonen et al., 2000). TMS voltages are thereby in the range of tens
of volts per metre, values that are typical for the endogenous fields
generated during normal and pathological brain activity (see above).
Therefore, since TMS induced modulations of the brain’s em field
affect brain function and behaviour, it follows that the brain’s
endogenous field must similarly influence neuronal computation.
The issue of the sensitivity of the human brain to weaker voltage
fluctuations is entangled with the powerline/mobile phone controversy,
which, despite many studies, remains contradictory and unresolved.
However, there is very solid in vitro evidence for very weak em fields
modulating neuronal function. Fields as weak as 10-20 V/m have been
shown to modulate neurone-firing patterns of Purkinje and stellate cells
in the isolated turtle cerebellum in vitro (Chan and Nicholson, 1986) or
the guinea-pig hippocampus (Jefferys, 1981). Electric field suppression
of epileptiform activity in rat hippocampal slices has been demonstrated
for fields as low as 5-10 V/m (Gluckman et al., 1996) and modulation of
hippocampal rhythmic slow activity in rats has been demonstrated in vivo
by weak extremely-low-frequency (ELF) magnetic fields (16.0 Hz; 28.9
mT) associated with induced electrical fields of only 100 mV/m (Jenrow
et al., 1998). A mollusc neurone has been shown to be capable of
responding to earth-strength (about 45 mT) magnetic fields (Lohmann et
al., 1991), associated with induced electrical fields of just 260 mV/m.
and later:
"it is perhaps significant that one of the few well-controlled studies of
the effects of microwave radiation on cognitive function in man
concluded that there was a small but significant effect on learning
(Preece et al., 1999) with a reduction in reaction times for repeated
tests in subjects exposed to the radiation."
Ironicly, this research supports Prof. McFadden's hypothesis: if there
are extracerebral effects on neuronal processes, then intracerebral EM
effects from signals generated by neurons themselves should also be
expected.
The correct answer to the objection to McFadden's hypothesis is
suggested by this statement by Prof. Persinger: "Consciousness is not a
continuous process but appears to be recreated transcerebrally every
approximately 20 msec to 25 msec (the 40 Hz binding factor). We
suspect that interfering with the end of one phase and the beginning of
another phase once every 20 to 25 msec may allow the brain access to
external information that typically it would never obtain." (Private
communication, Jan 11, 1999).
Professor McFadden
< http://www.surrey.ac.uk/SBS/ACADEMICS_homepage/mcfadden_johnjoe/pdfs
/McFadden%20cv.pdf >
should stick to his field, biochemistry and molecular genetics, and leave
biophysics to the biophysicists.
***************
If everyone remained in their home field, Pasteur would have continued
to study crystals and Francis Crick would have stuck to physics. Science
doesn't have boundaries.
[Touche' - WT]
johnjoe
Johnjoe McFadden, PhD
Professor of Molecular Genetics
School of Biomedical and Life Sciences
University of Surrey
Guildford,
Surrey, GU2 7XH, UK
tel: (44) 1483 686494
fax: (44) 1483 300374
email: j.mcfadden@surrey.ac.uk
--
Terry W. Colvin, Sierra Vista, [Cochise County] Arizona (USA)
Primary: < fortean1@mindspring.com >
Alternate: < terry_colvin@hotmail.com >
Home Page: < http://www.geocities.com/Area51/Stargate/8958/index.html >
Sites: * Fortean Times * Mystic's Haven * TLCB *
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