[FieldTrip] Standard BEM or FEM models for use with 256-electrode EEG data recorded with EGI caps (Laith Hamid)

[RICHARDS, JOHN]

Laith:

I have a “neurodevelopmental MRI database” (Richards, Sanchez et al., 2015; see my www site) that has average MRI templates that could be used.  Each average has the whole head down to about the top of the neck.  I did these purposely since I use EEG recording and the MNI template did not even go down far enough for the EGI 128 channel net.  

The database has average MRI templates for head (T1, T2) and brain.  I also have FEM segmented heads for the entire head that could be used for this.  Additionally, I have BEM segmented heads (e.g., brain, csf, skull, scalp), but ironically, I cut these off about 10% below the EGI 128 channel electrodes.  However, you could use the three inner compartments for this and just add the rest of the head below the compartment—or use the whole-head FEM as is for a FEM-model, or use the segmented area below the skull for a whole-head BEM model.  I also have average 128-channel EGI electrodes for each template.

Additionally, the “developmental” part of the “neurodevelopmental MRI database” is that I have these for a wide range of ages (all ages?).  I have a average for young adults (20-24 yrs), and average templates and FEM/BEM models for groups from 3 months through adulthood, and into late adulthood. So if you have specific neuro-pediatric applications you might be interested in using an age appropriate MRI average template rather than an adult template.  

See my www site for journal article references re this, and http://jerlab.psych.sc.edu/NeurodevelopmentalMRIDatabase/

Finally…  I have been using these head models for FT-based FEM and BEM models.  Possibly some of the actually field trip models I have would be useful to you.  Some of the parts of the model do not use the electrodes (e.g., grid-dipoles, head-model) whereas the final models (leadfield) requires the electrode locations. The database also includes “virtual” electrodes for the 10-10 system, which might be used to generate the 256 channel locations by knowing the relation between the 10-10 system and the EGI system based on EGI ELP files for the 256 channels.

John

***********************************************
John E. Richards Carolina Distinguished Professor
Department of Psychology
University of South Carolina
Columbia, SC  29208
Dept Phone: 803 777 2079
Fax: 803 777 9558
Email: richards-john at sc.edu
HTTP: jerlab.psych.sc.edu
***********************************************




>----------------------------------------------------------------------
>
>Message: 1
>Date: Tue, 19 Jan 2016 15:35:00 +0100
>From: Laith Hamid <lah at pedneuro.uni-kiel.de>
>To: fieldtrip at science.ru.nl
>Subject: [FieldTrip] Standard BEM or FEM models for use with
>	256-electrode EEG data recorded with EGI caps
>Message-ID: <0c2e8c0fa08db25ba3bb87c130fe0d7f at mail.uni-kiel.de>
>Content-Type: text/plain; charset="us-ascii"
>
> 
>
>Dear community, 
>
>My name is Laith Hamid and I am working in the University Medical
>Complex of Schleswig-Holstein in Kiel on source analysis of epileptic
>spikes and seizures. Currently I am analysing an EEG data set that was
>recorded using a 256-channel EGI system and I wanted to ask whether you
>have a standard BEM or FEM head model that extends enough downwards to
>accomodate all 256 electrodes. The current standard BEM model in the
>template folder of Fieldtrip isn't appropriate for source analysis of
>256-channel EGI data. 
>
>Thank you very much in advance for your help! 
>
>Best, 
>
>Laith