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

Stefan Debener s.debener at uke.uni-hamburg.de
Fri Jul 1 01:04:49 PDT 2005

Dear Alexei,
ideally, you want to place the CRT/LCD outside the recording booth. Our 
booth window comes with an electrically conductive sheet glass 
(virtually perfect visibility) that is part of the Farraday cage of the 
booth, and allows to present high quality visual stimuli on a CRT placed 
outside the booth. In addition, the subject seat is about 2 m away from 
the CRT, the amplifiers we use are battery powered, the booth lighting 
is low volt DC, etc.... In combination with a very good (separate) 
grounding of the booth, all this together results in (technically) clean 
recordings. Often, neither line noise nor monitor frequency related 
power is detectable in the spectrum, that is, power is below amplifier 
noise. However, in my experience, EEG contamination with muscle activity 
seems more of a problem for gamma band analysis.

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,
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Dr. Stefan Debener  
Institute of Neurophysiology and Pathophysiology 
Center of Experimental Medicine 
University Hospital Eppendorf 
Hamburg University 
Martinistr. 52 
D-20246 Hamburg 
Phone: ++49-40-42803-7644  
Fax: ++49-40-42803-7752  
Email: s.debener at uke.uni-hamburg.de 
URL: www.uke.uni-hamburg.de, www.debener.de  

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