LGMD with 3D morphology and active dendrites (Dewell & Gabbiani 2018)

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Accession:195666
This is a model of the locust LGMD looming sensitive neuron from Dewell & Gabbiani 2018. The morphology was constructed based on 2-photon imaging, and active conductances throughout the neuron were based on sharp electrode recordings in vivo.
Reference:
1 . Dewell RB, Gabbiani F (2018) Biophysics of object segmentation in a collision-detecting neuron. Elife [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): Locust Lobula Giant Movement Detector (LGMD) neuron;
Channel(s): I M; I h; Ca pump; I K,Ca; I T low threshold; I_KD;
Gap Junctions:
Receptor(s):
Gene(s):
Transmitter(s):
Simulation Environment: NEURON;
Model Concept(s): Active Dendrites; Synaptic Integration; Spatio-temporal Activity Patterns; Vision;
Implementer(s): Dewell, Richard Burkett [dewell at bcm.edu]; Gabbiani, F;
Search NeuronDB for information about:  I T low threshold; I M; I h; I K,Ca; I_KD; Ca pump;

/* --- Set Global Simulation Parameters --- */
showGUI = 1		// whether to open gui windows
msplit = 1		// whether to split across multiple threads
nmt = 8			// number of parallel threads to use (ignored if msplit == 0)
verbosity = 2	// verbosity level (0-4)
synCa = 3		// excitatory synapses cause Ca influx
/*------ */


/* --- Import the geometry and build cell  --- */
load_file("LGMDreconstruction_NEURON.hoc")
if (verbosity > 2) printf("3D morphology loaded \n")

objref siz
objref Ctines,Chandle
objref FieldA, TineEnds

siz = new SectionList()
forsec "soma" {
	siz.append()
}
forsec "SIZ" {
	siz.append()
}

FieldA = new SectionList()
forsec "MainTrunk"{
	FieldA.append()
}
forsec "Tines" {
	FieldA.append()
}

Ctines = new SectionList()
Chandle = new SectionList()
for i=0,21 {
	FieldC[i] {Chandle.append()}
}
for i=22,454 {
	FieldC[i] {Ctines.append()}
}
/*------ */


/* --- Load init files and utility functions --- */
load_file("init.hoc")
load_file("guisetup.hoc")
load_file("parinit.hoc")
load_file("mview.hoc")
load_file("Utilities.hoc")
if (verbosity > 2) printf("SimUtilities loaded \n")
load_file("Injection_procs.hoc")
if (verbosity > 2) printf("Injection_procs loaded \n")
/*------ */


/* --- Set Membrane Parameters --- */
gl = 1.0e-5		// base leak conductance (some sections set higher below)
el = -68		// leak reversal potential
Cm = 0.80		// membrane capacitance µF
axial = 220		// base axial resistivity Ωcm (some section changed below)
EK = -77		// K+ reversal potential
ENa = 60		// Na+ reversal potential
ECa = 150		// initial Ca2+ reversal potential (changes with Ca2+ influx and eflux)
SIZNa = 0.45	// sodium channel density at siz
gKdr = 1.0e-2	// base Kdr channel density
SIZM = 5.5e-3	// M channel density at siz
gcat = 1.4e-2	// CaT channeldensity
gkca = 1.3e-2	// KCa channel density
gcal = 2e-3		// CaL channel density


forall {
	Ra = axial
	cm = Cm
	insert pas
	g_pas = gl
	e_pas = el
}
/*------ */

/* --- Adjust channel densities for each section --- */

/*--- Axon --- */
forsec "Axon" {
	Ra=35
	insert M
	insert Na
	insert HH_Kdr
	insert h
	g_pas=gl*5
	gmax_M = SIZM/35
	gmax_Na = SIZNa/30
	gmax_HH_Kdr = gKdr
	gmax_h = 5e-5
	ek = EK
	ena = ENa
}
/*------ */

/*--- SIZ --- */
forsec siz {
	Ra=220
	insert Na
	insert HH_Kdr
	insert M
	insert KCa
	insert CaT
	insert CaL
	insert CaInternal
	g_pas = gl*5
	gmax_Na = SIZNa
	gmax_HH_Kdr = gKdr/4
	gmax_M = SIZM
	gmax_KCa = gkca
	gmax_CaT = gcat
	gmax_CaL = gcal
	ek = EK
	eca = ECa
	ena = ENa
}

forsec "ASIZ" Ra=600
forsec "DSIZ" Ra=100
/*------ */

/*--- Handle --- */
forsec "Handle" {
	Ra=60
	insert Na
	insert HH_Kdr
	insert M
	gmax_Na = 1.5e-2
	gmax_HH_Kdr = gKdr
	gmax_M = SIZM/40
	ek = EK
	ena = ENa
}
	/*--- procedure to set decreasing M density in handle--- */
	proc handle_M_dist() { local D, Mhalf, MS, Mmax, Mmin	// 
		Mmax = SIZM
		Mmin = 8.0e-5
		Mhalf = 25
		MS = -50
	
		soma[0] {distance()}
		forsec "Handle" {
			D = distance(.5)
			gmax_M = 0.27*(Mmin + (Mmax-Mmin)/(1+exp((Mhalf-D)/MS)))
		}
	}
	/*------ */
	/*--- procedure to set decreasing Na density in handle--- */
	proc handle_Na_dist() { local D, d_half, Namax, S, Namin
		Namin = 1.0e-2
		Namax = SIZNa
		d_half = 40
		S = -90
	
		soma[0] {distance()}
		forsec "Handle" {
			D = distance(.5)
			gmax_Na = 0.7*(Namin + (Namax-Namin)/(1+exp((d_half-D)/S)))
		}
	}
	/*------ */
for i=0,30 {		// Insert Ca in half of handle near SIZ
	Handle[i] {
	insert KCa
	insert CaT
	insert CaL
	insert CaInternal
	gmax_KCa = gkca
	gmax_CaT = gcat
	gmax_CaL = gcal
	eca=ECa
	}
}
/*------ */

/* --- Set cai influx and eflux for SIZ and handle Parameters --- */
forall if (ismembrane("CaInternal")) {
	alpha_ca_CaInternal = 6.25e-4	// determines ICa : cai ratio
	ca_init_CaInternal = 1.2e-3		// initial cai
	tau_ca_CaInternal = 400			// time constant of eflux (ms)
}
tmax_CaL=0.1
minca_KCa= 9.0e-4
pwr_KCa = 4
kD_ca_KCa= 3.0e-4
tau_KCa = 2
ca_min_CaInternal=1e-5
/*------ */


/*--- Field A --- */
forsec "MainTrunk"{
	Ra=120
	insert Na
	gmax_Na = 5e-3
	ena = ENa
}

forsec FieldA {
	insert HH_Kdr
	insert M
	insert NaP
	insert cdp
	insert CN
	insert hcn
	insert KD_ca3
	gmax_hcn = 1.2e-4
	gmax_HH_Kdr = gKdr/2
	gmax_M = SIZM/140
	gmax_NaP = 1e-4
	gmax_KD_ca3 = 4.0e-2
	ena = ENa
	ek = EK
}

TineEnds = new SectionList()
FindEnds(TineEnds,"Tines")
forsec TineEnds Ra=30
{Handle[20] distance() forsec FieldA gmax_hcn=0.4*gmax_hcn*(distance(0.5)/450)^6}	// set increasing hcn density
Zratio_g( FieldA, "Handle[60]", "hcn", 0, 0, 1, 1.25, 0.01 )	// set increasing hcn density

forsec FieldA gmax_KD_ca3= 3e-3 + gmax_hcn*140	// set increasing KD density

	/* --- Set Ca pump parameters for Field A--- */
	TotalPump_cdp = 8.5e-13
	TotalBuffer_cdp=0.04
	k1_cdp = 2.0
	k3_cdp = 0.5
	eca=ECa
	/*------ */
/*------ */


/*--- Inhibitory Fields B,C --- */
forsec "Field"{
	Ra=100
	insert M
	insert KdrF
	g_pas=gl*2
	gmax_M = 5.0e-5
	gmax_KdrF = 3.0e-03
	ek=EK
}

Zratio_g(Ctines, "FieldC[19]", "M", 1.25e-5, 30, 1,2)	// set increasing M density
Zratio_g("FieldB", "Handle[35]", "M", 1.25e-5, 30,1,2)	// set increasing M density

forsec Chandle {
	Ra=40
	if (ismembrane("NaP")) uninsert NaP
	if (ismembrane("h")) uninsert h
	insert HH_Kdr
	insert Na
	g_pas = gl
	gmax_HH_Kdr = gKdr
	gmax_Na = 4.0e-3
}
/*------ */

/*--- Neurite connecting the soma --- */
forsec "CellBody"{
	Ra=300
	insert NaP
	insert Na
	insert HH_Kdr
	gmax_NaP = 5.0e-5
	gmax_Na = 1.5e-2
	gmax_HH_Kdr = gKdr*2
	ek = EK
}
/*------ */

/*------ */


if (msplit) {
	// impedance measures only work in with single thread, so start multithread at end
	startPar()
}

if (showGUI) RunControlWindow()