Re: [Openeeg-list] help needed for initial readings using Olimex Modular EEG

[Niels S. <nie...@gm...>]

Hi Roberto, I've provided some answers below.
Op 11 mrt. 2012 00:31 schreef "Roberto Mir" <rm...@pu...> het volgende:
>
> Hi there,
> Thank you very much for all the information you have provided in the
openeeg project. I am getting very excited about projects involving EEG.
>
> I don't have any experience with EEG, but based on the information I've
found here, I bought an Olimex Modular EEG with 4 active electrodes and 1
passive electrode.
>
> I already set up the EEG in Windows XP to use with BrainBay software,
with a simple readout of the signal in both channels using an oscilloscope
in BrainBay.  I used a rubber band to place the electrodes in my head
(without any preparation): in FP1, FP2, O1 and O2. However, I haven't been
able to display any readout as the examples you have posted. It's more like
a random signal and it's very different from time to time.
>
> The signal from channel FP is like random signal, without any correlation
from time to time, and no change when I blink. The O signal is like random
noise.
>
> So I would really appreciate if any would answer or comment me about the
following questions:
>
> 1. Do active electrodes (from Olimex) require some preparation of the
scalp? Or can be placed directly to the skin or hair by using a rubber band
(or a cap)? What about the passive electrode that should be placed on the
ear?
>  I've also bought the modeeg Smt last week and setting it up was quite a
challenge. First, you can't connect these electrodes on areas covered with
hair. This results in a useless signal which will have impact on the other
channel as well. I guess it's the same as leaving one channel floating.  So
far I can only get a reliable signal when all four electrodes are connected
on the forehead. Attaching the DRL to that area or holding it between the
fingers is ok too. Doesn't have to be the earlobe. Also make sure to unplug
the powercord if you're using a laptop. Otherwise the signal will drown in
mains hum. At least that's what I've experienced with several different
laptops. I have not done any skin preparation so far but Olimex already
told me that this should improve the signal quality.

> 2. Is BrainBay and Windows a reliable mix for acquiring and visualising
EEG using Olimex modular EEG? Do you suggest other software or platform?
> Brainbay has been a great alternative to the expensive software out
there. It's very reliable. Updated frequently and working good with win7
also.
> 3. What´s the difference between modular eeg P2 and modular eeg P3?
BrainBay shows these 2 devices for configuration of the acquisition.
> Somebody else should fill you in on this one but I believe it is best to
use the standard (p2?) protocol for modeeg.

> 4. Should EEG measuring be done with the person quiet? Are there robust
methods for portable EEG acquisition during activities such as walking?

I think measuring brainactivity is done best with the person quiet becausd
otherwise you create too much artifacts in the signal due to movement.
Guess moving in a controlled pace with the head and electrodes remaining
very stationary could be maybe be done also.
>
> Any other guidance or suggestion would be very welcome, as I have no
prior experience with EEG acquisition and processing.
>
> Regards,
> Niels
>
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