Thalamic reticular neurons: the role of Ca currents (Destexhe et al 1996)

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Accession:17663
The experiments and modeling reported in this paper show how intrinsic bursting properties of RE cells may be explained by dendritic calcium currents.
Reference:
1 . Destexhe A, Contreras D, Steriade M, Sejnowski TJ, Huguenard JR (1996) In vivo, in vitro, and computational analysis of dendritic calcium currents in thalamic reticular neurons. J Neurosci 16:169-85 [PubMed]
Citations  Citation Browser
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 reticular nucleus GABA cell;
Channel(s): I Na,t; I T low threshold; I K; I Sodium; I Calcium; I Potassium;
Gap Junctions:
Receptor(s):
Gene(s):
Transmitter(s):
Simulation Environment: NEURON;
Model Concept(s): Action Potential Initiation; Dendritic Action Potentials; Bursting; Simplified Models; Active Dendrites; Influence of Dendritic Geometry; Detailed Neuronal Models; Action Potentials; Calcium dynamics;
Implementer(s): Destexhe, Alain [Destexhe at iaf.cnrs-gif.fr];
Search NeuronDB for information about:  Thalamus reticular nucleus GABA cell; I Na,t; I T low threshold; I K; I Sodium; I Calcium; I Potassium;
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dendre
cells
README
capump.mod *
HH2.mod *
IT2.mod
VClamp.mod *
El.oc *
leak.oc *
loc3.oc *
loc80.oc *
locD.oc *
mosinit.hoc *
re1_cc.oc
re3_cc.oc
re3_vc.oc
re80_cc.oc
re80_vc.oc
reD_cc.oc
reD_vc.oc
rundemo.hoc *
                            
/*----------------------------------------------------------------------------

	VOLTAGE-CLAMP SIMULATIONS OF RE CELLS
	=====================================

	- passive and structural parameters estimated from SimFit
	- electrode with adjustable series resistance
	- simulations at 24 degC
	- special run procedure for calculating the peak current
	- calcium diffusion
	- Q10=2.5


	  ** voltage-clamp in reconstructed RE cell with 80 compartment **


  For more details, see:

  Destexhe, A., Contreras, D., Steriade, M., Sejnowski, T.J. and Huguenard,
  J.R.  In vivo, in vitro and computational analysis of dendritic calcium
  currents in thalamic reticular neurons.  J. Neurosci. 16: 169-185, 1996.

  See also:

  http://www.cnl.salk.edu/~alain
  http://cns.fmed.ulaval.ca

----------------------------------------------------------------------------*/



//----------------------------------------------------------------------------
//  load and define general graphical procedures
//----------------------------------------------------------------------------

// xopen("$(NEURONHOME)/lib/hoc/stdrun.hoc")
load_file("nrngui.hoc")

objectvar g[20]			// max 20 graphs
ngraph = 0

proc addgraph() { local ii	// define subroutine to add a new graph
				// addgraph("variable", minvalue, maxvalue)
	ngraph = ngraph+1
	ii = ngraph-1
	g[ii] = new Graph()
	g[ii].size(tstart,tstop,$2,$3)
	g[ii].xaxis()
	g[ii].yaxis()
	g[ii].addvar($s1,1,0)
	g[ii].save_name("graphList[0].")
	g[ii].exec_menu("Keep Lines")
	graphList[0].append(g[ii])
}

if(ismenu==0) {
  nrnmainmenu()			// create main menu
  nrncontrolmenu()		// create control menu
}




//----------------------------------------------------------------------------
//  transient time
//----------------------------------------------------------------------------

trans = 1000

print " "
print ">> Transient time of ",trans," ms"
print " "





//----------------------------------------------------------------------------
//  create multi-compartment geometry and insert currents
//----------------------------------------------------------------------------

xopen("cells/re80.geo")	// read geometry file

corrD = 1			// dendritic surface correction

forall { 			// insert passive current everywhere
	insert pas
	g_pas = 5e-5 * corrD	// (from simfit)
	e_pas = -72.843		// (from simfit)
	cm = 1 * corrD		// (from simfit)
	Ra = 260		// (from simfit)
	L = L
}

soma {
	g_pas = 5e-5		// (from simfit)
	cm = 1			// (from simfit)
}


forall {
	insert it2		// T-current everywhere
	cai = 2.4e-4 
	cao = 2 
	eca = 120 
	shift_it2 = 0		// no shift of ITs
	gcabar_it2 = corrD * 0.0002
	qm_it2 = 2.5		// low q10
	qh_it2 = 2.5

	insert cad		// calcium diffusion everywhere
	depth_cad = corrD	// NEED TO BE RESCALED
	kt_cad = 0		// no pump
	kd_cad = 1e-4
	taur_cad = 5
	cainf_cad = 2.4e-4	
}



xopen("loc80.oc")	// load procedure for localizing T-current


localize(4.5e-5, 4.5e-5, 4.5e-5) 	// initial distribution of T-current



	




//----------------------------------------------------------------------------
//  insert electrode in the soma
//----------------------------------------------------------------------------

// note load_file command only executed if not executed yet for that file in current session
load_file("El.oc")		// Electrode with series resistance

access soma
objectvar El			// insert electrode
El = new Electrode()
electrodes_present=1

//
// VOLTAGE-CLAMP MODE
//

	forall { g_pas = 0 }		// remove passive current everywhere

	soma El.vc.loc(0.5)		// put electrode in voltage-clamp mode
	El.vc.dur[0] = trans-20
	El.vc.dur[1] = 10
	El.vc.dur[2] = 1000
	El.vc.amp[0] = -110
	El.vc.amp[1] = -110
	El.vc.amp[2] = -30
	El.vc.rs = 5	 		// series resistance
					// 49.79 megohm from simfit


//----------------------------------------------------------------------------
//  setup simulation parameters
//----------------------------------------------------------------------------

Dt = 0.2
npoints = 2000

objectvar Sim			// create vector of simulation points
Sim = new Vector(npoints)

dt = 0.1			// must be submultiple of Dt
tstart = trans-100
tstop = trans + npoints * Dt
runStopAt = tstop
steps_per_ms = 1/Dt
celsius = 24
v_init = -70





//----------------------------------------------------------------------------
//  procedures for voltage-clamp protocol
//----------------------------------------------------------------------------

proc run2() {				// new run procedure
	run()
	peak_current = Sim.min()
	print "Peak current = ",peak_current
}


proc init() {				// initialization procedure
	finitialize(v_init)
	fcurrent()
	index = 0			// add definition of an index
	peak_current = 0		// define peak current
}


proc step() {local i			// advance-one-step (Dt) procedure
	Plot()
	if(t >= trans) {
		Sim.set(index,El.vc.i)	// memorize data only after trans
		index = index + 1
	}
	for i=1,nstep_steprun {
		advance()
	}
}

vmin = -110				// values of protocol
vmax = -40
vstep = 5

proc run_vc() {				// general procedure for v-clamp
	for(vhold=vmin; vhold<vmax+vstep; vhold=vhold+vstep) {
		El.vc.amp[0] = vhold
		run2()
	}
}

proc make_VCpanel() {			// make panel
	xpanel("VC")
	xpvalue("Start holding potential",&vmin)
	xpvalue("End holding potential",&vmax)
	xpvalue("Step potential",&vstep)
	xbutton("Start protocol","run_vc()")
	xpanel()
}

make_VCpanel()



//----------------------------------------------------------------------------
//  add graphs
//----------------------------------------------------------------------------

addgraph("El.vc.i",-0.5,0.0001)
addgraph("soma.v(0.5)",-120,0)
//addgraph("dend1[3].v(0.5)",-120,40)  	// for dissociated cell
//addgraph("dend1[3].v(0.5)",-120,40)	// for intact cell
//addgraph("dend1[8].v(0.5)",-120,40)	// for intact cell
addgraph("dend1[12].v(0.5)",-120,40)	// for intact cell