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

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

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: Powers RK, Elbasiouny SM, Rymer WZ, Heckman CJ (2011) Contribution of Intrinsic Properties and Synaptic Inputs to Motoneuron Discharge Patterns: A Simulation Study. J Neurophysiol [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 motor neuron;
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 motor neuron;

Model files

Help downloading and running models

This is the README for the model associated with the paper

Powers RK, ElBasiouny SM, Rymer WZ and Heckman CJ. Contributions of
intrinsic properties and synaptic inputs to motoneuron discharge
patterns: a simulation study.  J Neurophys, 107:808-823, 2012.

These files were contributed by Randy Powers.

Usage: This archive contains all the files necessary to produce the
responses of a medium threshold motoneuron to the triangular
current-clamp, voltage-clamp and noisy conductance commands used in
Powers et al. 2012.  These simulations use and require that NEURON
(http://www.neuron.yale.edu)
is installed. The base code and mod files are in the subfolder "code".
The files for initiating the simulations and for specifying the
parameters for a medium threshold motoneuron are in the subfolder
"MN_hoc_and_output".

Either auto-launch from ModelDB or compile the mod files in the code
folder with mknrndll (MacOS and mswin) or by typing "nrnivmodl code"
(unix/linux).  You can start the simulation by with either the
mosinit.hoc file, init_synss.hoc, or init_gramp.hoc.  The former
allows you to select either of the latter by clicking a button.  The
file init_synss.hoc is used for current-clamp and voltage-clamp
simulations, whereas init_gramp.hoc is used for the simulating
responses to synaptic conductance commands.


Upon running init_synss.hoc, the NEURON Main Menu and a window
entitled "FR motoneuron control panel" will appear.  Click the pick a
file button and pick Medium_thresh_MN.hoc. Then click Exit on the file
chooser. Then click the "Choose analysis" button and pick either FI
for the current-clamp simulation or IV for the voltage-clamp
simulation.  If you click "GO" the "IV" simulation will generate
Fig. 1E:



and Fig. 1F:



After the simulation is finished an output text file is
generated that either lists injected current and spike time values
(for current-clamp) or voltage command and voltage-clamp current
values (for voltage clamp).  For the voltage-clamp simulation you have
the option of looking at the effects of tonic excitatory input, by
clicking the enable synaptic input button.

Upon running init_gramp.hoc you can record the responses to the
various mixtures of excitatory and inhibitory input used in Powers et
al. 2012 by executing the commands in the file gramp_commands.

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