query on coherence source analysis

Muthuraman Muthuraman muthuraman10 at HOTMAIL.COM
Tue May 2 11:02:06 CEST 2006


Thanks for the Previous suggestions

i would like to know whether there is prescribed algorithm in Fieldtrip
to calculate the coherent source analysis  between the EEG and EMG data

with regards

>From: Robert Oostenveld <r.oostenveld at FCDONDERS.RU.NL>
>Reply-To: FieldTrip discussion list <FIELDTRIP at NIC.SURFNET.NL>
>Subject: Re: [FIELDTRIP] query on coherence and layout
>Date: Mon, 3 Apr 2006 22:22:02 +0200
>Hi Muthuraman
>On 3 Apr 2006, at 11:00, Muthuraman Muthuraman wrote:
>>I have used freqdescriptives to calculate the coherence between EEG  and
>>the problem is i get a very less coherence value from 0.01 to 0.1
>>is there the range specified in the programs
>Coherence in the range from 0.01 to 0.1 in itself is not uncommon.  The
>values depend on the number of trials and tapers (since it is a  biassed
>measure). You should look at its spectral distribution and on  the scalp
>topography to see whether it makes sense.
>>and what is the method you use to calculate the coherence can you  give a
>>brief explanation
>Coherence is explained in books on signal processing, or you can do a
>google for it. In Matlab you can also type "help CSD".
>>i have also a problem with the layout
>>i would like to create my own layout if it is  possible
>>how it can be done
>>because in the the previous mail you have mentioned about the  elec1010
>>layout file
>>but it does not match my requirements
>>do i need the CTF software for this in all the layout files it is
>>mentioned to be CTF 151 and so on.
>You should open one of the layout files in a text editor as example.  The
>columns are
>   number, xpos, ypos, width, height, label
>You can manually make your own layout file in a text editor, or using  some
>custom matlab code if you already know within Matlab what your  electrode
>locations are.
>best regards,

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