From: Moritz Dannhauer <moritz@sci.utah.edu>

Subject: Re: Again regarding scirun 5 and brain stimulator

Date: September 1, 2015 3:21:15 PM MDT

To: G Abouelseoud <la.ilah.illa.allah@yandex.com>

Cc: Ayla Khan <ayla@sci.utah.edu>, Dana Brooks <brooks@ece.neu.edu>, Rob MacLeod <macleod@sci.utah.edu>

Dear G. Abouelseoud, thank you for your email.

1. In the brain stimulator data set (released with scirun 5), why is the truncation from below classified as scalp (see attached figure from paraview threshold filter)?

This data set / segmentation is based on the original released Colin27 data set. Its used in many parts of  neuroscience and most of those applications are focused on imaging the brain rather than the entire head. We have not decided when we will release another model (0.5 mm voxelsize) but that one will contain the neck.  

2. How is this truncation from below compensated for in simulation (do you apply certain absorbing boundary condition, for example)?

Boundary conditions: There is only current going in the volume at the electrodes - everything else (volume boundary) is electrical isolated.

3. In the net with scirun 4.7 SCIRUN_TDCS_simulation.srn: the current is calculated as sigma*grad(phi), shouldn't be -sigma*grad(phi) ?(I am just pointing it out because in some applications, the direction of current density matters not just magnitude and because I want to sure I am not missing something)

Yes, the current direction matters very much. Its just very simple to visualize the magnitude. You can change the network as you like or we can do it for you.

Thank you for your time, support and patience and once again God bless you all.

Thank you for your request and hope it helps!

Best,
Moritz