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]
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_18
FivecompthTAlw_18.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 = 25.898312354570635
soma.L = 3299.4371099168975
soma.g_pas = 0.0002251219113573407
soma.e_pas = -71.4872565096953
soma.gbar_na3rp = 0.01584725761772853
soma.gbar_naps = 2.307626349030471e-05
soma.sh_na3rp = 1.0
soma.sh_naps = 5.0
soma.ar_na3rp = 1.0
soma.ar_naps = 1.0
soma.gMax_kdrRL = 0.017436444099722993
soma.gcamax_mAHP = 7.3735474610538585e-06
soma.gkcamax_mAHP = 0.0005230570637119113
soma.taur_mAHP = 60.7626528531856
soma.ek = -80.0
soma.Ra = 0.001
soma.cm = 1.6103429916897507
soma.ghbar_gh = 0.0001274575844875346
soma.half_gh = -77.0
forsec dend{
L = 2005.018970304709
diam = 10.277751662049862
g_pas = 0.0001260000512465374
e_pas = -71.4872565096953
gcabar_L_Ca_inact = 0.00011010504155124654
Ra = 46.027206271468145
cm = 0.8739334099722992
ghbar_gh = 0.0001274575844875346
half_gh = -77.0
}
d1.gcabar_L_Ca_inact = 0.00010108332409972299
d2.gcabar_L_Ca_inact = 0.00011108332409972299
d3.gcabar_L_Ca_inact = 0.00011851556786703601
d4.gcabar_L_Ca_inact = 0.000133515567867036
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 = -40.538131745152356
tau_m_L_Ca_inact = 40.0
theta_h_L_Ca_inact = 0.2542415512465386
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 = 0.9119002770083071

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