Motoneuron pool input-output function (Powers & Heckman 2017)

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Accession:239582
"Although motoneurons have often been considered to be fairly linear transducers of synaptic input, recent evidence suggests that strong persistent inward currents (PICs) in motoneurons allow neuromodulatory and inhibitory synaptic inputs to induce large nonlinearities in the relation between the level of excitatory input and motor output. To try to estimate the possible extent of this nonlinearity, we developed a pool of model motoneurons designed to replicate the characteristics of motoneuron input-output properties measured in medial gastrocnemius motoneurons in the decerebrate cat with voltage- clamp and current-clamp techniques. We drove the model pool with a range of synaptic inputs consisting of various mixtures of excitation, inhibition, and neuromodulation. We then looked at the relation between excitatory drive and total pool output. Our results revealed that the PICs not only enhance gain but also induce a strong nonlinearity in the relation between the average firing rate of the motoneuron pool and the level of excitatory input. The relation between the total simulated force output and input was somewhat more linear because of higher force outputs in later-recruited units. ..."
Reference:
1 . Powers RK, Heckman CJ (2017) Synaptic control of the shape of the motoneuron pool input-output function. J Neurophysiol 117:1171-1184 [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;
Channel(s):
Gap Junctions:
Receptor(s):
Gene(s):
Transmitter(s):
Simulation Environment: NEURON;
Model Concept(s):
Implementer(s): Powers, Randy [rkpowers at u.washington.edu];
Search NeuronDB for information about:  Spinal cord lumbar motor neuron alpha ACh cell;
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RPCH_JNP17
FivecompthTAlw
FivecompthTAlw_0
FivecompthTAlw_0.hoc
                            
//uses dpath of 700 from M1   alternative atten fact for ht (more atten)
//modified from hTA to make parameters for last MN same as previous MN_14
soma.diam = 22.0
soma.L = 2952.0
soma.g_pas = 8.109e-05
soma.e_pas = -71.0
soma.gbar_na3rp = 0.01
soma.gbar_naps = 2.6e-05
soma.sh_na3rp = 1.0
soma.sh_naps = 5.0
soma.ar_na3rp = 1.0
soma.ar_naps = 1.0
soma.gMax_kdrRL = 0.015
soma.gcamax_mAHP = 6.4e-06
soma.gkcamax_mAHP = 0.00045
soma.taur_mAHP = 90.0
soma.ek = -80.0
soma.Ra = 0.001
soma.cm = 1.35546
soma.ghbar_gh = 3e-05
soma.half_gh = -77.0
forsec dend{
L = 1794.13
diam = 8.73071
g_pas = 7.93445e-05
e_pas = -71.0
gcabar_L_Ca_inact = 9.5e-05
Ra = 51.038
cm = 0.867781
ghbar_gh = 3e-05
half_gh = -77.0
}
d1.gcabar_L_Ca_inact = 8.5e-05
d2.gcabar_L_Ca_inact = 9.5e-05
d3.gcabar_L_Ca_inact = 0.0001
d4.gcabar_L_Ca_inact = 0.000115
qinf_na3rp = 8.0
thinf_na3rp = -50.0
vslope_naps = 5.0
asvh_naps = -90.0
bsvh_naps = -22.0
mvhalfca_mAHP = -20.0
mtauca_mAHP = 2.0
celsius = 37.0
theta_m_L_Ca_inact = -42.0
tau_m_L_Ca_inact = 40.0
theta_h_L_Ca_inact = 10.0
tau_h_L_Ca_inact = 2500.0
kappa_h_L_Ca_inact = 5.0
htau_gh = 30.0
mVh_kdrRL = -21.0
tmin_kdrRL = 0.8
taumax_kdrRL = 20.0
V0 = -15.0