A model of closed-loop motor unit including muscle spindle feedback (Kim, 2020)

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Accession:266732
Persistent inward current generating ion channels are located over spinal motoneurons and actively recruited during normal behaviors. Constructing a realistic computational model of closed-loop motor unit, a motoneuron and muscle fibers that it innervates including muscle spindle afferents, the study reveals functional linkage between persistent inward current location, motoneuron discharge pattern and muscle force output at various muscle lengths. This systematic analysis may provide useful insights into interplay of spinal and muscular mechanisms in control of movements.
Reference:
1 . Kim H (2020) Linking Motoneuron PIC Location to Motor Function in Closed-Loop Motor Unit System Including Afferent Feedback: A Computational Investigation. eNeuro [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: Spinal motoneuron;
Cell Type(s):
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): Motor control;
Implementer(s): Kim, Hojeong [hojeong.kim03 at gmail.com];
Search NeuronDB for information about:  I Sodium; I Calcium; I Potassium; I_AHP;
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Kim2020
fig9
Ca_conc.mod *
CaL.mod *
CaN.mod *
KCa.mod *
KDr.mod *
module1_2.mod *
module3.mod *
mStepIClamp.mod
Naf.mod *
Nap.mod *
syn_Ia_sinewave.mod
Xm.mod *
add_hil_is.hoc *
add_muscle_unit.hoc *
add_pics_istim.hoc
Ca_conc.o *
CaL.o *
CaN.o *
fig.ses
fixnseg.hoc *
group_Ia_sinewave.hoc
KCa.o *
KDr.o *
mem_mechanism_acti.hoc *
mem_mechanism_muscle.hoc *
mem_mechanism_pass.hoc *
mod_func.c
mod_func.o
module1_2.o *
module3.o *
motor_unit.hoc
mStepIClamp.o
Naf.o *
Nap.o *
nrnmech.dll
syn_Ia_sinewave.o
v_e_moto6_export.hoc *
Xm.hoc *
Xm.o *
                            
TITLE Persistent Sodium Channel

NEURON {
	SUFFIX Nap
	USEION na READ ena WRITE ina
	RANGE gnapbar, ina, g, i
}

UNITS {
	(mA) = (milliamp)
	(mV) = (millivolt)
	(S)  = (siemens)
}

PARAMETER {
	gnapbar	=0.0008 	(mho/cm2) <0,1e9>
}

ASSIGNED {
	v (mV)
	ena (mv)
	ina (mA/cm2)
	i (mA/cm2)
	g (S/cm2)
	minf mtau
}

STATE {
	m
}

BREAKPOINT {
	SOLVE states METHOD cnexp
	g = gnapbar * m * m * m
	i = g * (v - ena)
	ina = i
}

INITIAL { :Assume v has been constant for a long time
	rates(v)
	m = minf
}

DERIVATIVE states { :Computes state variable m and h at present v & t
	rates(v)
	m' = (minf - m)/mtau
}

PROCEDURE rates(v(mV)) {LOCAL a, b
	a = (-0.0353*(v+21.4))/(exp(-(v+21.4)/5)-1)
	b = (0.000883*(v+25.7))/(exp((v+25.7)/5)-1)
	mtau = 1/(a + b)
	minf = a/(a + b)
}

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