// \$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(8) stim_amp.fill(0) stim_amp.x[2]=1 stim_amp.x[3]=1 stim_amp.x[4]=-1 stim_amp.x[5]=-1 stim_amp.x[6]=0 stim_amp.x[7]=0 stim_amp.mul(\$3) // now the time vector stim_time.resize(8) 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+\$2 stim_time.x[6]=\$1+\$2+\$2 stim_time.x[7]=\$1+\$2+\$2+\$2 } 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)