A model of slow motor unit (Kim, 2017)

 Download zip file   Auto-launch 
Help downloading and running models
Accession:235769
Cav1.3 channels in motoneuron dendrites are actively involved during normal motor activities. To investigate the effects of the activation of motoneuron Cav1.3 channels on force production, a model motor unit was built based on best-available data. The simulation results suggest that force potentiation induced by Cav1.3 channel activation is strongly modulated not only by firing history of the motoneuron but also by length variation of the muscle as well as neuromodulation inputs from the brainstem.
Reference:
1 . Kim H (2017) Muscle length-dependent contribution of motoneuron Cav1.3 channels to force production in model slow motor unit. J Appl Physiol (1985) 123:88-105 [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): Spinal cord lumbar motor neuron alpha ACh cell; Skeletal muscle cell;
Channel(s): I Calcium; I Potassium; I Sodium; I_AHP;
Gap Junctions:
Receptor(s):
Gene(s): Cav1.3 CACNA1D;
Transmitter(s):
Simulation Environment: NEURON;
Model Concept(s): Active Dendrites;
Implementer(s): Kim, Hojeong [hojeong.kim03 at gmail.com];
Search NeuronDB for information about:  Spinal cord lumbar motor neuron alpha ACh cell; I Sodium; I Calcium; I Potassium; I_AHP;
/
Kim2017
fig5
Ca_conc.mod *
CaL.mod *
CaN.mod *
KCa.mod *
KDr.mod *
module1_2.mod *
module3.mod *
mStepSyn.mod
Naf.mod *
Nap.mod *
Xm.mod *
add_hil_is.hoc *
add_muscle_unit.hoc *
add_pics_syns.hoc
CaL_PICs.hoc *
fig5.ses
fixnseg.hoc *
mem_mechanism_acti.hoc *
mem_mechanism_muscle.hoc *
mem_mechanism_pass.hoc *
motor_unit.hoc
v_e_moto6_export.hoc *
Xm.hoc *
                            
TITLE Modified Hill-Mashima muscle model
 
UNITS {}

NEURON {
    SUFFIX fHill
    RANGE a0, b0, c0, d0
	RANGE p0, g1, g2, g3
	RANGE Kse, A, Fc, F
	RANGE xm_init, xm, xce_init, xce
	USEION mg READ mgi VALENCE 2
	USEION cl READ cli
}

PARAMETER {
	a0 = 2.35		:[N]
	b0 = 24.35		:[mm*s-1]
	c0 = -7.4		:[N]
	d0 = 30.3		:[mm*s-1]
	p0 = 23			:[N]
	g1 = -8			:[mm]
	g2 = 21.4		:[mm]
	xm_init = -8	:[mm]
	xce_init = -8	:[mm]
	Kse = 0.4		:[mm-1]
}

STATE {
	A
	xce
	xm
}

ASSIGNED {
	F
	Fc
	mgi		
	cli		
}

BREAKPOINT { LOCAL d_xm, d_xce, d_se
	A = mgi	
	xm = cli	

	SOLVE state_hill METHOD cnexp
		
	F = p0*Kse*xse(xm, xce)
}

DERIVATIVE state_hill {
	Fc = p0*g(xm)*A
	xce' = dxdt (F, Fc)
}

FUNCTION xse (x, y) { LOCAL d_xm, d_xce, d_se
	d_xm = xm - xm_init
	d_xce = xce - xce_init
	d_se = d_xm - d_xce
	
	if (d_se <= 0) {xse = 0} 
	else {xse = d_se}
}

FUNCTION g (x) { 
	g = exp(-((x-g1)/g2)^2)
}

FUNCTION dxdt (x, xc) {LOCAL gain_length 
	if (x <= xc) {
		dxdt = (10^-3)*(-b0*(xc-x))/(x+a0*xc/p0)
	} else {
		gain_length = (-d0*(xc-x))/(2*xc-x+c0*xc/p0)
		if (gain_length <= 0) {dxdt = (10^-3)*1e5}
		else {dxdt = (10^-3)*gain_length}
	}
}

INITIAL {
	A = 0
	xm = xm_init
	xce = xce_init
	F=1e-5     
}

Loading data, please wait...