[Eeglablist] laplacian in subdural

[Luis Garcia Dominguez]

Dear Arnaud,
Thank you for your answer. I just read also about a new "reference free" 
method that calculates the new potentials as subtracted from an 
electrode placed at infinity. (Dezhong Yao /et al/ 2005 /Physiol. Meas./ 
*26* 173-184). The method involves the calculation of lead-field 
matrices assuming an equivalent source distribution. This seems to be an 
interesting approach for everyone who use bivariate measures that can be 
greatly affected by referential montages. I hope it will be incorporated 
into EEGLab in the near future. Thanks again,
Luis

Arnaud Delorme wrote:
> Dear Luis,
>
> no you do not need to provide the original montage (just the location 
> file that correspond to the electrode location but the reference does 
> not need to be specified). It seems the laplacian is indeed be 
> reference free because it is unaffected by any offset common to all 
> channels.
>
> Best,
>
> Arno
>
> Luis Garcia Dominguez wrote:
>> Hi everybody,
>> I want to use the laplacian montage in subdural recordings (to make 
>> it reference free) using the function del2map. It seems to me that 
>> the only requirement is to provide the data and the proper location 
>> file. Is there any need to specify the original montage?  I guess not 
>> but I want to hear it from you. Any advice for my specific case? Thanks,
>> Luis
>
>
>