Issues with stim provided through vtx files

Question

Hello,

I am stimulating a mesh with 2 stimuli specified as under:
 

    stim = [

            '-num_stim'                , 2,

            '-stim[0].crct.type'       , 0,

            '-stim[0].pulse.strength'  , 60.0,

            '-stim[0].ptcl.duration'   , 1.0,

            '-stim[0].ptcl.start'      , 7,

            '-stim[0].ptcl.npls'       , 1,

            '-stim[0].name'            , "S1",

            '-stim[0].elec.vtx_file'   , "S1.vtx",

            '-stim[1].crct.type'       , 0,

            '-stim[1].pulse.strength'  , 60.0,

            '-stim[1].ptcl.duration'   , 1.0,

            '-stim[1].ptcl.start'      , 15,

            '-stim[1].ptcl.npls'       , 1,

            '-stim[1].name'            , "S2",

            '-stim[1].elec.vtx_file'   , "S2.vtx", ]

The two stimuli are provided 7 and 15ms after the start. When I apply this example to slab with "stimulus" option, it works fine, but with external VTX files, the simulation seems to show that S1 initiates fine and by the time it reaches 15ms S2 does not "add" to S1 but rather replaces it - as S1 shows no activity any more..

Any guesses what I could be doing wrong?

Here is a sample S1.vtx

2
extra
9
10 

Many thanks
~anoop

Answer 1

Hi!

Given that you expected the currents to add up, I am assuming that S1.vtx and S2.vtx are overlapping. Your observation is correct. openCARP does not support boundary conditions with overlapping electrodes.

Best, Aurel

Comments

Yes that was it. Thank you.

~anoop