// $Id: stim.hoc,v 1.5 2009/02/24 00:55:27 ted Exp ted $
/* The stimulus is constructed from a waveform template 
that is copied to a Vector.
For each section that has the xtra mechanism, this Vector 
is used to drive is_xtra.
The transfer resistance rx_xtra takes care of the 
amplitude and sign of the local extracellular field.
*/


// create basic stimulus waveform
// for this example use a simple rectangular pulse 

// default values
DEL = 1  // ms
DUR = 1
AMP = -0.05  // mA

// this works with fixed dt and adaptive integration
objref stim_amp, stim_time
stim_amp = new Vector()
stim_time = new Vector()

proc stim_waveform() {
  // this uses interpolated play
  // index    0  1    2    3        4        5
  // stim vec 0, 0,   1,   1,       0        0
  // time vec 0, DEL, DEL, DEL+DUR, DEL+DUR, DEL+DUR+1
  //  really  0, $1,  $1,  $1+$2,   $1+$2,   $1+$2+1
  // first the stim vector
  stim_amp.resize(6)
  stim_amp.fill(0)
  stim_amp.x[2]=1
  stim_amp.x[3]=1
  stim_amp.mul($3)
  // now the time vector
  stim_time.resize(6)
  stim_time.x[1]=$1
  stim_time.x[2]=$1
  stim_time.x[3]=$1+$2
  stim_time.x[4]=$1+$2
  stim_time.x[5]=$1+$2+1
}


ATTACHED__ = 0

proc attach_stim() {
// since is_xtra is GLOBAL, we only need to specify Vector.play()
// for one instance of xtra, i.e. at just one internal node
// of only one section that contains xtra
  forall {  // check each section to find one that has xtra
    if (ATTACHED__ == 0) {  // don't bother if stim is already attached to something
      if (ismembrane("xtra")) {
        stim_amp.play(&is_xtra, stim_time, 1) // "interpolated" play
        ATTACHED__ = 1
      }
    }
  }
}


proc setstim() {
  del = $1
  dur = $2
  amp = $3
  stim_waveform(del, dur, amp)
  attach_stim()
}


setstim(DEL, DUR, AMP)

print "Use setstim(del, dur, amp) to change latency (ms), duration (ms),"
print "and amplitude (mA) of extracellular stimulus current."

xpanel("Extracellular Stimulus Current", 0)
  xvalue("del (ms)", "DEL", 1, "setstim(DEL,DUR,AMP)", 0, 1)
  xvalue("dur (ms)", "DUR", 1, "setstim(DEL,DUR,AMP)", 0, 1)
  xvalue("amp (mA)", "AMP", 1, "setstim(DEL,DUR,AMP)", 0, 1)
xpanel(73,497)