Study: Cell Phones 'Excite' the Brain, Discovery News

Blootstelling aan de straling van een GSM telefoon (45 minuten) geeft tot een uur na de blootstelling een sterk activerend effect op de hersenschors (cortex). Er is dus een effect, maar de wetenschappers zijn er niet over uit of dit een potentieel schadelijk of misschien zelfs gunstig effect is. Na placeboblootstelling (nepmobieltje) was er geen enkel effect te zien in de hersenschors. Hieronder volgt het artikel van Discovery News:

By Rossella Lorenzi, Discovery News
dsc.discovery.com/news/briefs/20060522/cellphonesexcite_hea.html

May 25, 2006— Cell phone exposure stirs the brain, according to an Italian study which investigated the effects of mobile phone emissions on the motor cortex.

The study, accepted for publication in the Annals of Neurology, proved that the electromagnetic fields generated by cell phones produce an increase in excitability within the brain's cortex.

The cortex is the largest part of the human brain, associated with higher brain function.

''We still do not know whether this effect is neutral or potentially dangerous or beneficial to brain functioning,'' Paolo Maria Rossini, a neurologist with the Fatebenefratelli IRCCS Research Center of Brescia, told Discovery News.

Rossini and colleagues used a technique called paired-pulse transcranial magnetic stimulation to investigate cortical excitability in 15 healthy young male volunteers. Each volunteer was exposed to emissions from phones using the Global System for Mobile Communications, or GSM.

The researchers mounted a common GSM phone to the left side of the subject's head by using a modified helmet that assured a constant distance of 15 mm between phone and ear.

An identical phone, without battery, was positioned on the right side of the head.

''In order to mimic conditions associated with normal use during exposure, the subjects were allowed to move around the experiment room and to chat with the experimenters,'' wrote the researchers.

The volunteers underwent two sessions, one week apart. One session featured a 45-minute cell phone exposure, while the other was a ''sham''— a 45-minute session in which no phone was turned on, although subjects were told the opposite.

The researchers performed the paired-pulse procedure three times during each session —before, immediately after exposure and an hour after the phone was turned off.

The results were ''surprising,'' Rossini said. In the sham sessions and just before the phones were turned on, both hemispheres showed no excitability changes.

But when the researchers looked at the brain during phone emissions, they found ''an excitability increase in the exposed left hemisphere'' as compared to the non-exposed side of the head and the sham exposure.

The effect lasted up to one hour after the end of exposure.

While further studies are now necessary to establish whether intense use of cellular phones is harmful, there may be a way to actually harness the effect for therapeutic purposes.

A small, preliminary trial last year led by Eman M. Khedr, from Assiut University Hospital in Egypt suggested that exposure to intermittent magnetic fields may facilitate recovery after stroke.

''Exposure to GSM-type electromagnetic fields may theoretically provide a new, non-invasive method to treat subjects suffering from neurological diseases with reduced cortical excitability, such as strokes and Alzheimer's disease,'' Rossini said.



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