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

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" ... 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."
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]
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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;
Gap Junctions:
Simulation Environment: NEURON;
Model Concept(s): Activity Patterns; Bursting; Action Potentials;
Implementer(s): Powers, Randy [rkpowers at];
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strdef startloc, codeloc, myfile
strdef start_dir
start_dir = getcwd()

// code location is 1 directory up, under the "code" directory
startloc = getcwd()
{sprint(codeloc, "%s../code", codeloc)}

type = unix_mac_pc()
{sprint(codeloc, "%s../code", startloc)}
if (type == 3) { // this is a mswin PC
    {sprint(myfile, "%s/nrnmech.dll", codeloc)}
} else { // this is a unix OS
    //    {sprint(myfile, "%s/i686/.libs/", codeloc)}
    {sprint(myfile, "%s/umac/.libs/", codeloc)}
// load the compiled dll

// Base code
{sprint(myfile, "%s/FRMotoneuronNaHH.hoc", codeloc)}

access dendrite
insert Gfluctdv
access soma
insert Gfluctdv