Simulations of motor unit discharge patterns (Powers et al. 2011)

 Download zip file   Auto-launch 
Help downloading and running models
Accession:143671
" ... To estimate the potential contributions of PIC (Persistent Inward Current) activation and synaptic input patterns to motor unit discharge patterns, we examined the responses of a set of cable motoneuron models to different patterns of excitatory and inhibitory inputs. The models were first tuned to approximate the current- and voltage-clamp responses of low- and medium-threshold spinal motoneurons studied in decerebrate cats and then driven with different patterns of excitatory and inhibitory inputs. The responses of the models to excitatory inputs reproduced a number of features of human motor unit discharge. However, the pattern of rate modulation was strongly influenced by the temporal and spatial pattern of concurrent inhibitory inputs. Thus, even though PIC activation is likely to exert a strong influence on firing rate modulation, PIC activation in combination with different patterns of excitatory and inhibitory synaptic inputs can produce a wide variety of motor unit discharge patterns."
Reference:
1 . Powers RK, Elbasiouny SM, Rymer WZ, Heckman CJ (2012) Contribution of intrinsic properties and synaptic inputs to motoneuron discharge patterns: a simulation study. J Neurophysiol 107:808-23 [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;
Channel(s):
Gap Junctions:
Receptor(s):
Gene(s):
Transmitter(s):
Simulation Environment: NEURON;
Model Concept(s): Activity Patterns; Bursting; Action Potentials;
Implementer(s): Powers, Randy [rkpowers at u.washington.edu];
Search NeuronDB for information about:  Spinal cord lumbar motor neuron alpha ACh cell;
/
PowersEtAl2012
code
Gfluctdv.mod *
ghchan.mod *
kca2.mod *
kdrRL.mod *
L_Ca.mod *
mAHP.mod *
na3rp.mod *
naps.mod *
synss.mod
ana_FI.hoc
ana_G.hoc
ana_passive.hoc
ana_vc.hoc
ana_vc_synss.hoc
AP_AHP.ses
FIgraph.hoc
FRcablepas.hoc
FRmnrampcc.ses
FRmnrampvc_synss.ses
FRMotoneuronNaHH.hoc
gramp.ses
GUI_FR_analysis.hoc
inhibdist
makebiramp.hoc *
passive.ses
RecActive.hoc
re-init.hoc
SetConductances.hoc
test.hoc
twobirampsdel.hoc *
vramp
vrampdel
vrampdel.hoc
                            
// Cat FR motoneuron model (reduced morphology)
//
// This file constructs the equivalent cylinder of the 3D dendritic morphology of cat FR MN (cell 43/5 in Cullheim et al., 1987)
// The reduced model reproduce the passive properties of the full morphology faithfully
// Reduced model passive properties:    Rin = 1.38 MOhm, tau(0)=6.8 ms,  tau(1) = 1.5 ms (graphical peeling method)
// Experimental data of same MN:        Rin = 1.4 MOhm,  tau(0)=6.82 ms, tau(1) = 1.57 ms
//
// Sherif Elbasiouny
// 07/01/2009
//////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

//load_file("nrngui.hoc")					// Load Neuron

create soma, is, dendrite, axonhillock
access soma


// connect model sections
connect is(1), axonhillock(0)
connect axonhillock(1), soma(0)
connect soma(1), dendrite(0)



// Define anatomical and biophysical properties of each section

soma {
	nseg = 1		      // 1 compartment
	L = 48.8	            // [um] length
	diam = 48.8	            // [um] diameter

 	insert pas	            // standard passive current
	g_pas = 1/225	      // [S/cm^2] conductance for leak current
	e_pas = -70.0	      // [mV] equilibrium potential for leak
}


is {
	nseg = 5		      // 5 compartment (changed by RP for better behavior)
	L = 30			// [um] length
	diam = 3.3		      // [um] diameter

	insert pas	            // standard passive current
	g_pas = 1/1000   // [S/cm^2] conductance for leak current; changed from 225 by RP
	e_pas = -70			// [mV] equilibrium potential for leak
}


axonhillock {
	nseg = 11		      // 11 compartments
	L = 15			// [um] length; changed by RP to reflect Conradi
	diam(0:1) = 3.3:13		// [um] diameter increase

	insert pas	            // standard passive current
	g_pas = 1/1000    // [S/cm^2] conductance for leak current; changed from 225 by RP
	e_pas = -70			// [mV] equilibrium potential for leak
}


dendrite {
	nseg = 19		      // 19 compartments
	L = 6675		      // [um] total length of the equivalent dendrite
	diam = 40		      // [um] diameter of the stem
	diam(0.3:1) = 40:1      // [um] tapering of the distal dendrite

	insert pas         	// standard passive current
	g_pas = 1/11000	     	// [S/cm^2] conductance for leak current
	e_pas = -70		      // [mV] equilibrium potential for leak
}

forall {
	Ra = 70          		// [ohm.cm]
	cm = 1          		// [uf/cm2]
}

Loading data, please wait...