Axon-somatic back-propagation in a detailed model of cat spinal motoneuron (Balbi et al, 2015)

 Download zip file   Auto-launch 
Help downloading and running models
Morphologically detailed conductance-based models of cat spinal alpha motoneurons have been developed, with the aim to reproduce and clarify some aspects of the electrophysiological behavior of the antidromic axon-somatic spike propagation. Fourteen 3D morphologically detailed somata and dendrites of cat spinal alpha motoneurons have been imported from an open-access web-based database of neuronal morphologies,, and instantiated in neurocomputational models.
1 . Balbi P, Martinoia S, Massobrio P (2015) Axon-somatic back-propagation in detailed models of spinal alpha motoneurons Front. Comput. Neurosci. 9:15
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: Spinal motoneuron;
Cell Type(s): Spinal cord motor neuron;
Channel(s): I Na,p; I Na,t; I K; I h; I K,Ca; I Calcium;
Gap Junctions:
Simulation Environment: NEURON;
Model Concept(s):
Implementer(s): Balbi, Pietro [piero.balbi at];
Search NeuronDB for information about:  Spinal cord motor neuron; I Na,p; I Na,t; I K; I h; I K,Ca; I Calcium;
Readme file

The present files complement the paper:

Balbi P, Martinoia S and Massobrio P (2015) Axon-somatic
back-propagation in detailed models of spinal alpha
motoneurons. Front. Comput. Neurosci. 9:15. doi:

Pietro Balbi, december 2014

A morphologically detailed model of cat spinal alpha-motoneuron.  The
present implementation takes advantage of the somato-dendritic
morphologically detailed 3D reconstructions available on-line at  The present simulation also extensively adopts, with
few changes:

a) the channels mechanisms by "Powers RK, ElBasiouny SM, Rymer WZ,
Heckman CJ. Contribution of intrinsic properties and synaptic inputs
to motoneuron discharge patterns: a simulation study. J Neurophysiol
(2012) 107: 808-823";

b) a model of myelinated motor axon by "McIntyre CC, Richardson AG,
Grill WM. Modeling the excitability of Mammalian nerve fibers:
influence of afterpotentials on the recovery cycle. J Neurophysiol
(2002) 87:995-1006".  Both these models are available at ModelDB,
accession numbers 143671 and 3810, respectively.

'1_mosinit.hoc' initializes the simulation and displays the panel for
choosing amongst 14 detailed motoneurons. When a choice is made, the
corresponding 3D morphologically detailed reconstructions are
implemented into the model. The file also loads a previously saved
steady-state (300 ms without stimuli, to stabilize the resting
potential across the cell membrane). If a steady-state is not desired,
please set flag_svstate=1 from the interpreter.

'2_complete_cell.hoc' loads the 3_ to 7_ files in sequence.

'3_ins_ch.hoc' inserts the ionic channels at the appropriate locations
(see paper for details) onto soma and dendrites, then sets the
relative conductances.

'4_AHIS.hoc' creates an axon hillock and an axonal initial segment,
joins them to the soma, inserts the ionic channel and the relative
conductances onto them.

'5_axon.hoc' creates the myelinated axon with the corresponding
geometric and biophysical features, and attaches it to the distal end
of the initial segment.

'6_ax_term.hoc' creates the unmyelinated ending of the axon.

'7_morphometry' displays on the default output some morphometric
values of the model (in Italian).

The directory 'channels' contains the .mod files to instantiate the
mechanisms of passive and active channels.

The directory 'cat_spinal_mn' contains the 3D data imported from

The directory 'States' contains the saved steady-states of each neuron.

Use of the model: load the mosinit.hoc file to start (in the channels

To replicate the simulations in the paper, after choosing the
preferred motoneuron a stimulating electrode should be inserted in a
distal node (node[15], for example), and the recording ones both in a
proximal node (only avoid node[0], because it is deleted during the
neuron 3D construction), the axonal initial segment and the soma, thus
detecting the voltage attenuation of the antidromic wave.  Changing
the geometric and sodium conductance parameters of the initial segment
affects the voltage attenuation at a point when the antidromic spike
invasion of the soma can happen.  It is convenient to change the
geometric and conductance parameters from the .hoc file (4_AHIS.hoc),
to be sure that the axon hillock parameters consistently change.  To
speed up the simulations, the VariableStepControl can be set on.  The
model also carries the extracellular mechanism.

The model only represents a first, coarse approximation of a spinal
alpha-motoneuron. In particular, the electrophysiological behaviour of
the dendritic part has not been extensively tested.

P.S.: apologize for multiple untranslated comments in Italian inside
the .hoc files.

Balbi P, Martinoia S, Massobrio P (2015) Axon-somatic back-propagation in detailed models of spinal alpha motoneurons Front. Comput. Neurosci. 9:15

References and models cited by this paper

References and models that cite this paper

Alvarez FJ, Pearson JC, Harrington D, Dewey D, Torbeck L, Fyffe RE (1998) Distribution of 5-hydroxytryptamine-immunoreactive boutons on alpha-motoneurons in the lumbar spinal cord of adult cats. J Comp Neurol 393:69-83 [PubMed]

   [24 reconstructed morphologies on NeuroMorpho.Org]

ARAKI T, TERZUOLO CA (1962) Membrane currents in spinal motoneurons associated with the action potential and synaptic activity. J Neurophysiol 25:772-89 [Journal] [PubMed]

Ascoli GA, Donohue DE, Halavi M (2007) NeuroMorpho.Org: a central resource for neuronal morphologies. J Neurosci 27:9247-51 [Journal] [PubMed]

Balbi P, Martinoia S, Colombo R, Massobrio P (2014) Modelling recurrent discharge in the spinal a-motoneuron: Reappraisal of the F wave Clin Neurophysiol 125(2):427-9 [Journal] [PubMed]

   Recurrent discharge in a reduced model of cat spinal motoneuron (Balbi et al, 2013) [Model]

Barrett EF, Barrett JN, Crill WE (1980) Voltage-sensitive outward currents in cat motoneurones. J Physiol 304:251-76 [PubMed]

Barrett JN, Crill WE (1974) Specific membrane properties of cat motoneurones. J Physiol 239:301-24 [PubMed]

Barrett JN, Crill WE (1980) Voltage clamp of cat motoneurone somata: properties of the fast inward current. J Physiol 304:231-49 [PubMed]

Berthold CH, Nilsson I, Rydmark M (1983) Axon diameter and myelin sheath thickness in nerve fibres of the ventral spinal root of the seventh lumbar nerve of the adult and developing cat. J Anat 136 (Pt 3):483-508 [PubMed]

Berthold CH, Rydmark M (1983) Electrophysiology and morphology of myelinated nerve fibers. VI. Anatomy of the paranode-node-paranode region in the cat. Experientia 39:964-76 [PubMed]

Booth V, Rinzel J, Kiehn O (1997) Compartmental model of vertebrate motoneurons for Ca2+-dependent spiking and plateau potentials under pharmacological treatment. J Neurophysiol 78:3371-85 [Journal] [PubMed]

BROCK LG, COOMBS JS, ECCLES JC (1953) Intracellular recording from antidromically activated motoneurones. J Physiol 122:429-61 [PubMed]

Burbidge SA, Dale TJ, Powell AJ, Whitaker WR, Xie XM, Romanos MA, Clare JJ (2002) Molecular cloning, distribution and functional analysis of the NA(V)1.6. Voltage-gated sodium channel from human brain. Brain Res Mol Brain Res 103:80-90

Burke RE, Strick PL, Kanda K, Kim CC, Walmsley B (1977) Anatomy of medial gastrocnemius and soleus motor nuclei in cat spinal cord. J Neurophysiol 40:667-80 [PubMed]

Carnevale NT, Hines ML (2006) The NEURON Book

Carnevale NT, Tsai KY, Claiborne BJ, Brown TH (1995) The electrotonic transformation: a tool for relating neuronal form to function Advances In Neural Information Processing Systems, Tesauro G:Touretzky DS:Leen TK, ed. pp.69

Catterall WA, Goldin AL, Andwaxman SG (2014) Voltage-Gated Sodium Channels,Introduction 82:2014

Cisi RR, Kohn AF (2008) Simulation system of spinal cord motor nuclei and associated nerves and muscles, in a Web-based architecture. J Comput Neurosci 25:520-42 [Journal] [PubMed]

   Simulation system of spinal cord motor nuclei and assoc. nerves and muscles (Cisi and Kohn 2008) [Model]

Clark BD, Goldberg EM, Rudy B (2009) Electrogenic tuning of the axon initial segment. Neuroscientist 15:651-68 [PubMed]

Clements JD, Redman SJ (1989) Cable properties of cat spinal motoneurones measured by combining voltage clamp, current clamp and intracellular staining. J Physiol 409:63-87 [PubMed]

Conradi S (1969) Observations on the ultrastructure of the axon hillock and initial axon segment of lumbosacral motoneurons in the cat. Acta Physiol Scand Suppl 332:65-84 [PubMed]

Cullheim S, Fleshman JW, Glenn LL, Burke RE (1987) Membrane area and dendritic structure in type-identified triceps surae alpha motoneurons. J Comp Neurol 255:68-81 [PubMed]

   [6 reconstructed morphologies on NeuroMorpho.Org]

Cullheim S, Kellerth JO (1978) A morphological study of the axons and recurrent axon collaterals of cat sciatic alpha-motoneurons after intracellular staining with horseradish peroxidase. J Comp Neurol 178:537-57 [PubMed]

Diwakar S, Magistretti J, Goldfarb M, Naldi G, D`Angelo E (2009) Axonal Na+ channels ensure fast spike activation and back-propagation in cerebellar granule cells J Neurophysiol 101(2):519-32 [Journal] [PubMed]

   Multicompartmental cerebellar granule cell model (Diwakar et al. 2009) [Model]

Dodge FA, Cooley JW (1973) Action Potential of the Motorneuron. IBM J Res Dev 17:219-29 [Journal]

   Spinal Motor Neuron (Dodge, Cooley 1973) [Model]

Duflocq A, Chareyre F, Giovannini M, Couraud F, Davenne M (2011) Characterization of the axon initial segment (AIS) of motor neurons and identification of a para-AIS and a juxtapara-AIS, organized by protein 4.1B. BMC Biol 9:66

ECCLES JC (1955) The central action of antidromic impulses in motor nerve fibres. Pflugers Arch 260:385-415 [PubMed]

Elbasiouny SM, Bennett DJ, Mushahwar VK (2005) Simulation of dendritic CaV1.3 channels in cat lumbar motoneurons: spatial distribution. J Neurophysiol 94:3961-74 [Journal] [PubMed]

Fleshman JW, Segev I, Burke RB (1988) Electrotonic architecture of type-identified alpha-motoneurons in the cat spinal cord. J Neurophysiol 60:60-85 [Journal] [PubMed]

Gentet LJ, Stuart GJ, Clements JD (2000) Direct measurement of specific membrane capacitance in neurons. Biophys J 79:314-20 [PubMed]

Goldstein SS, Rall W (1974) Changes of action potential shape and velocity for changing core conductor geometry. Biophys J 14:731-57 [PubMed]

Hay E, Hill S, Schurmann F, Markram H, Segev I (2011) Models of neocortical layer 5b pyramidal cells capturing a wide range of dendritic and perisomatic active properties. PLoS Comput Biol 7:e1002107 [Journal] [PubMed]

   [3 reconstructed morphologies on NeuroMorpho.Org]
   Cortical Layer 5b pyr. cell with [Na+]i mechanisms, from Hay et al 2011 (Zylbertal et al 2017) [Model]
   L5b PC model constrained for BAC firing and perisomatic current step firing (Hay et al., 2011) [Model]

Hendrickson EB, Edgerton JR, Jaeger D (2011) The capabilities and limitations of conductance-based compartmental neuron models with reduced branched or unbranched morphologies and active dendrites. J. Comp. Neurosci. 30(2):301-321 [Journal] [PubMed]

   Comparison of full and reduced globus pallidus models (Hendrickson 2010) [Model]

Hodgkin AL, Huxley AF (1952) A quantitative description of membrane current and its application to conduction and excitation in nerve. J Physiol 117:500-44 [Journal] [PubMed]

   Squid axon (Hodgkin, Huxley 1952) (LabAXON) [Model]
   Squid axon (Hodgkin, Huxley 1952) (NEURON) [Model]
   Squid axon (Hodgkin, Huxley 1952) (SNNAP) [Model]
   Squid axon (Hodgkin, Huxley 1952) used in (Chen et al 2010) (R language) [Model]
   Squid axon (Hodgkin, Huxley 1952) (SBML, XPP, other) [Model]

Hu W, Tian C, Li T, Yang M, Hou H, Shu Y (2009) Distinct contributions of Na(v)1.6 and Na(v)1.2 in action potential initiation and backpropagation. Nat Neurosci 12:996-1002 [Journal] [PubMed]

   Action Potential initiation and backpropagation in Neocortical L5 Pyramidal Neuron (Hu et al. 2009) [Model]

Joyner RW, Westerfield M, Moore JW (1980) Effects of cellular geometry on current flow during a propagated action potential. Biophys J 31:183-94 [PubMed]

   Current flow during PAP in squid axon at diameter change (Joyner et al 1980) [Model]

Kernell D (1966) Input resistance, electrical excitability, and size of ventral horn cells in cat spinal cord. Science 152:1637-40 [PubMed]

Kole MH, Ilschner SU, Kampa BM, Williams SR, Ruben PC, Stuart GJ (2008) Action potential generation requires a high sodium channel density in the axon initial segment. Nat Neurosci 11:178-86 [Journal] [PubMed]

   [1 reconstructed morphology on NeuroMorpho.Org]
   Na+ channel dependence of AP initiation in cortical pyramidal neuron (Kole et al. 2008) [Model]

Kuo CC, Bean BP (1994) Na+ channels must deactivate to recover from inactivation. Neuron 12:819-29 [PubMed]

López-Aguado L, Ibarz JM, Varona P, Herreras O (2002) Structural inhomogeneities differentially modulate action currents and population spikes initiated in the axon or dendrites. J Neurophysiol 88:2809-20 [PubMed]

Liu RH, Yamuy J, Xi MC, Morales FR, Chase MH (1995) Changes in the electrophysiological properties of cat spinal motoneurons following the intramuscular injection of adriamycin compared with changes in the properties of motoneurons in aged cats. J Neurophysiol 74:1972-81 [PubMed]

Luscher HR, Larkum ME (1998) Modeling action potential initiation and back-propagation in dendrites of cultured rat motoneurons. J Neurophysiol 80:715-29 [Journal] [PubMed]

McIntyre CC, Grill WM (2002) Extracellular stimulation of central neurons: influence of stimulus waveform and frequency on neuronal output. J Neurophysiol 88:1592-604 [Journal] [PubMed]

McIntyre CC, Richardson AG, Grill WM (2002) Modeling the excitability of Mammalian nerve fibers: influence of afterpotentials on the recovery cycle. J Neurophysiol 87:995-1006 [Journal] [PubMed]

   Spinal Motor Neuron (McIntyre et al 2002) [Model]

Moore JW, Stockbridge N, Westerfield M (1983) On the site of impulse initiation in a neurone. J Physiol 336:301-11 [PubMed]

   Site of impulse initiation in a neuron (Moore et al 1983) [Model]

Morales FR, Boxer PA, Fung SJ, Chase MH (1987) Basic electrophysiological properties of spinal cord motoneurons during old age in the cat. J Neurophysiol 58:180-94

Nilsson I, Berthold CH (1988) Axon classes and internodal growth in the ventral spinal root L7 of adult and developing cats. J Anat 156:71-96 [PubMed]

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(3):808-23 [Journal] [PubMed]

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

(47 refs)