[Eeglablist] What type of monitor gives less noise in the neuropsychology experiment?

Campbell, Tom tom.campbell at helsinki.fi
Fri Jul 1 01:16:31 PDT 2005


There is a literature on how radiation from mobile phones interferes with 
brain activity, mostly in a journal called Bioelectromagnetics. I'd be 
interested if anyone comes across some investigations that look at 
different types of monitor radiation in a similar way.

See also:
Title: Cellular phone electromagnetic field effects on bioelectric 
activity of human brain 
Author(s): Lebedeva NN, Sulimov AV, Sulimova OP, Kotrovskaya TI, Gailus T 
Source: CRITICAL REVIEWS IN BIOMEDICAL ENGINEERING 28 (1-2): 323-337 2000 

There is an interesting article on investigations with rabbits:

Title: Nonlinear changes in brain electrical activity due to cell phone 
radiation 
Author(s): Marino AA, Nilsen E, Frilot C 
Source: BIOELECTROMAGNETICS 24 (5): 339-346 JUL 2003 
Document Type: Article 
Language: English 
Cited References: 32      Times Cited: 2        
Abstract: We studied the effect of an electromagnetic field from a 
cellular telephone on brain electrical activity, using a novel analytical 
method based on a nonlinear model. The electroencephalogram (EEG) from 
rabbits was embedded in phase space and local recurrence plots were 
calculated and quantified using recurrence quantitation analysis to permit 
statistical comparisons between filtered segments of exposed and control 
epochs from individual rabbits. When the rabbits were exposed to the 
radiation from a standard cellular telephone (800 MHz band, 600 mW maximum 
radiated power) under conditions that simulated normal human use, the EEG 
was significantly affected in nine of ten animals studied. The effect 
occurred beginning about 100 ms after initiation of application of the 
field and lasted similar to300 ms. In each case, the fields increased the 
randomness in the EEG. A control procedure ruled out the possibility that 
the observations were a product of the method of analysis. No differences 
were found between exposed and control epochs in any animal when the 
experiment was repeated after the rabbits had been sacrificed, indicating 
that absorption of radiation by the EEG electrodes could not account for 
the observed effect. No effect was seen when deposition of energy in the 
brain was minimized by repositioning the radiating antenna from the head 
to the chest, showing that the type of tissue that absorbed the energy 
determined the observed changes in the EEG. We conclude that, in normal 
use, the fields from a standard cellular telephone can alter brain 
function as a consequence of absorption of energy by the brain. (C) 2003 


So, it would seem a good idea to keep mobiles well out of the lab, not 
least because they produce sounds that can influence brain processes in a 
way unrelated to the experiment. 
-- 
best regards,
________________________________________________________________________
Tom Campbell                             e-mail:tom.campbell at helsinki.fi
Helsinki Collegium for Advanced Studies  tel: +358-9 191 23256
University of Helsinki, Finland          fax: +358-9 191 22924
P.O.Box 4 (Fabianinkatu 24)              home: +358-4 154 09764 
FIN-00014 University of Helsinki
Finland
________________________________________________________________________



Quoting GWMobile <geopilot at mindspring.com>:

> CRT's give out TERRIBLE NOISE IN THE 60 and 30 HTZ RANGE. IF YOU DO ANY 
> LOW LEVEL RECORDING WITH THE MONITER ON IT WILL INTRODUCE SUCH A HUM 
> INTO ANY AMPLIFIED ELECTROMAGNETIC INPUT (including even microphones) AS
> 
> TO MAKE IT UNUSEABLE.
> 
> 
> I have found I must turn the crt's off beofre recording and then back on
> 
> when finished.
> 
> Additionaly some cellphones such as sidekicks and blue tooth devices 
> give off loud intermittent bursts of signals. Balckberrys treo and 
> sidekicks if within 2 feet of a car radio with actually be easily heard 
> in the car radio.
> 
> I think lcds are much lower however best is to eleimate all equipment 
> 20ft from the area and turn off what you can't eliminate.
> 
> 
> On Thu, 30 Jun 2005 9:57 am, Alexei A. Morozov wrote:
> > Dear colleagues,
> >
> > Could you please give me an advice.
> > I am going to automate a neuropsychology experiment.
> > The visual stimulus will be demonstrated on the computer monitor.
> > So, the question is what type of computer monitor
> > produces less noise - LCD of CRT?
> > I have read that TFT (LCD) monitor produces less noise, but it has
> > the vertical scanning frequency 56 - 75 Hz, that intersects with
> > the Gamma frequencies that we want to measure.
> > Well, could anybody tell me please what type of monitor
> > gives less noise in the neuropsychology experiment?
> > Have anybody compared various types of computer monitors?
> >
> > Thank you,
> >
> > Alexei
> >  
> >
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> Typed from my mobile phone. Please excuse the typos!
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