T-type Ca current in thalamic neurons (Wang et al 1991)

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Accession:53893
A model of the transient, low-threshold voltage-dependent (T-type) Ca2+ current is constructed using whole-cell voltage-clamp data from enzymatically isolated rat thalamocortical relay neurons. The T-type Ca2+ current is described according to the Hodgkin-Huxley scheme, using the m3h format, with rate constants determined from the experimental data.
Reference:
1 . Wang XJ, Rinzel J, Rogawski MA (1991) A model of the T-type calcium current and the low-threshold spike in thalamic neurons. J Neurophysiol 66:839-50 [PubMed]
Model Information (Click on a link to find other models with that property)
Model Type: Neuron or other electrically excitable cell;
Brain Region(s)/Organism:
Cell Type(s): Thalamus geniculate nucleus/lateral principal GLU cell;
Channel(s): I T low threshold;
Gap Junctions:
Receptor(s):
Gene(s):
Transmitter(s):
Simulation Environment: NEURON;
Model Concept(s): Activity Patterns; Ion Channel Kinetics; Oscillations;
Implementer(s): Morse, Tom [Tom.Morse at Yale.edu];
Search NeuronDB for information about:  Thalamus geniculate nucleus/lateral principal GLU cell; I T low threshold;
/
ca_t_lva
readme.txt
lva.mod
fig3.hoc
fig3.ses
mosinit.hoc
                            
// fig3.hoc creates fig3 p843 from Wang et al 1991

load_file("nrngui.hoc")
load_file("fig3.ses") // session of gui created windows for testing manually further
 
// First create some vectors for the voltage clamps for fig3A and fig3B
 
objref VC3A, VC3B
save_dt = dt
save_steps_per_ms = steps_per_ms

// steps_per_ms = 10
// dt = 0.1

// note: obj = new Vector(size, filled_initial_value) and num_of_time_points = tstop/dt + 1
 
VC3A = new Vector( 150/dt + 1, -42 )
VC3B = new Vector( 600/dt + 1, -42 )
 
// additionally add regions of -92 to VC3B
// note: vsrcdest.fill(value, start, end) places "value" into vec between indicies
VC3B.fill( -92, 0, 10/dt )                       // first 5ms is -92 mV
VC3B.fill( -92, 210/dt + 1, 260/dt + 1 )        // a later 50ms duration is -92

strdef tmpstr

objref fig3graphs, fig3Atop, fig3Abottom
objref fig3Btop, fig3Bmiddle, fig3Bbottom, fig3graph[5]

// vectors to be graphed
objref tmpxvec, tmpyvec
objref m, d, h


tmpxvec=new Vector()	// holds quantites to be graphed
tmpyvec=new Vector()	// holds quantites to be graphed

tmpxvec.record(&t)

proc graphmaker() {
// ($1 graphnumber, $2 tstop, $3 steps_per_ms, $4 dt, $5 startx, $6 stopx, $7 starty, $8 stopy)
fig3graph[$1] = new Graph()
fig3graph[$1].size($5, $6, $7, $8)

{tstop =$2 steps_per_ms=$3 dt=$4 init() run()}

}

fig3graphs = new VBox()
fig3graphs.intercept(1)

// graphmaker arguments:
// ($1 graphnumber, $2 tstop, $3 steps_per_ms, $4 dt, $5 startx, $6 stopx, $7 starty, $8 stopy)

  tmpyvec.record(&soma.i_lva(0.5))
 
  tstop = 150
  xpanel("")
  xlabel("Fig 3A  Wang et al 1991")
  xpanel()
  VC3A.play(&OClamp[0].vc, dt)
  graphmaker(0,        150,        steps_per_ms,dt,      0,      150,         -0.025, 0)
  tmpyvec.line(fig3graph[0], tmpxvec)
  fig3graph[0].label(.85,.7,"I_T")

  tstop = 600
  objref VC3A
  VC3B.play(&OClamp[0].vc, dt)

// for this next graph record the m, d, and h states

  m = new Vector(tstop/dt +1)
  d = m.c
  h = m.c
  m.record(&soma.m_lva(0.5))
  d.record(&soma.d_lva(0.5))
  h.record(&soma.h_lva(0.5))
  graphmaker(1,         150,          steps_per_ms,dt,      0,       150,         0, 1)
  m.line(fig3graph[1], tmpxvec, 2, 0)
  d.line(fig3graph[1], tmpxvec, 3, 0)
  h.line(fig3graph[1], tmpxvec, 4, 0)
  fig3graph[1].label(.5,.8,"m")
  fig3graph[1].label(.3,.6,"d")
  fig3graph[1].label(.6,.3,"h")

  xpanel("")
  xlabel("Fig 3B")
  xpanel()

// ($1 graphnumber, $2 tstop, $3 steps_per_ms, $4 dt, $5 startx, $6 stopx, $7 starty, $8 stopy)
  graphmaker(2,        600 ,         steps_per_ms,dt,       0,       600,         -0.025, 0)
  tmpyvec.line(fig3graph[2],tmpxvec)
  fig3graph[2].label(.85,.7,"I_T")
  
  graphmaker(3,        600 ,         steps_per_ms,dt,       0,       600,             0, 1)
  m.line(fig3graph[3], tmpxvec, 2, 0)
  d.line(fig3graph[3], tmpxvec, 3, 0)
  h.line(fig3graph[3], tmpxvec, 4, 0)
  fig3graph[3].label(.2,.8,"m")
  fig3graph[3].label(.7,.7,"d")
  fig3graph[3].label(.8,.2,"h")

  fig3graph[4] = new Graph()
  fig3graph[4].size(0,       600,         -100, -30)

  VC3B.line(fig3graph[4], tmpxvec)
  fig3graph[4].label(.9,.5, "V")

fig3graphs.intercept(0)
fig3graphs.map("fig 3 Wang et al 1991", 550, 20, 350, 800)

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