[Eeglablist] Using EEGlab to quantify individual frequencies at specific times

[Enrico Glerean]

Hi
Supposing that in theory you have no artifacts in the data, then you could
write a script in matlab that loads each EEG file (using the load functions
of EEGlab), then highpass filter the data so that you remove anything under
150Hz (e.g. with attenuation of -40db) and then compute the RMS as function
of time with a given sliding time window (e.g. 200ms). What you obtain is
the power signal in time foreach electrode for f>150Hz. Then you can
identify maxima and see if there is something significant in that frequency
band.

In a real life situation you have to consider that your data might have
artifacts and consider the SNR of your machine at the given frequency band.
I am no rat-expert so I have no idea what kind of powers are expected for
rats at f>150Hz, but if they are comparable to the electric background noise
of the machine, then you have to consider more sofisticated ways to clean
your data (neural network filtering, oversampling, etc etc)

I hope this helps!

best regards

Enrico Glerean

2009/6/12 Chris Holdgraf <choldgra at tulane.edu>

> I've got a large number of continuous EEG files from rats (about 15min
> each) and I want to sort through this data and quantify where there are
> bands of >=150Hz neural activity. I've looked through the manual but can't
> find anything that fits just what I need.  Does anyone know how this might
> be accomplished?  Basically, I just need to know A. If there is activity at
> or above 150Hz and B. When this activity is taking place (which electrode
> this occurs on would be nice as well).
> Thanks
> Chris
>
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