Muscle spindle feedback circuit (Moraud et al, 2016)

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Accession:189786
Here, we developed a computational model of the muscle spindle feedback circuits of the rat ankle that predicts the interactions between Epidural Stimulation and spinal circuit dynamics during gait.
Reference:
1 . Moraud EM, Capogrosso M, Formento E, Wenger N, DiGiovanna J, Courtine G, Micera S (2016) Mechanisms Underlying the Neuromodulation of Spinal Circuits for Correcting Gait and Balance Deficits after Spinal Cord Injury. Neuron 89:814-28 [PubMed]
Model Information (Click on a link to find other models with that property)
Model Type: Realistic Network;
Brain Region(s)/Organism: Spinal motoneuron;
Cell Type(s): Spinal cord motor neuron slow twitch;
Channel(s): I K; I K,Ca; I Na,p; I Sodium;
Gap Junctions:
Receptor(s):
Gene(s):
Transmitter(s):
Simulation Environment: NEURON; Python;
Model Concept(s): Sensory processing; Neuromodulation;
Implementer(s): Capogrosso, Marco ; Formento, Emanuele ;
Search NeuronDB for information about:  I Na,p; I K; I K,Ca; I Sodium;
public is_art
public init, topol, basic_shape, subsets, geom, biophys, geom_nseg, biophys_inhomo
public synlist, x, y, z, position, connect2target, synapses
public soma, dendrite, inseg, node, paranode
public all

//Loading network parameters
{xopen("SetNetworkSize.hoc")}

nnode=41

{create soma[1.]}
{create dendrite[ndend]}
{create inseg[1.]}
{create node[nnode]}
{create paranode[nnode]}

objref synlist
objectvar stim

proc init() {
  //geom()
  synlist = new List()
  //synapses()
  x = y = z = 0 // only change via position
}


objref all
proc subsets() { local i
  objref all
  all = new SectionList()
    soma all.append()
    dendrite all.append()
}


objectvar D
objectvar file
objectvar Leq
objref r

proc geom() {
     r=new Random($1)
  xopen("MN_ballstick_axon.hoc")

forsec "soma" {
  cm=2
  Ra=200
  // insert motoneuron           // McIntyre
  insert motoneuron_5ht          // MN with 5HT drug effect -- Booth et al 1997
  }

forsec "dendrite" {
       Ra = 200
       cm = 2
       insert pas
       g_pas = 7.7e-6 //FLESHMAN ET AL 1988 - cells 35/4
       e_pas = -70.0
       }

for i=0, nnode-1 {
  node[i]{
       nseg=1
       Ra = 70
       cm = 2
       insert axnode
       gnapbar_axnode=0
  }
}
forsec "paranode" {
    nseg=5
    Ra = 70
    cm=0.1/(2*9.15*diam+2*30) //This is 0.1/2*nl where nl=9.15*D+30 is the number of myelin lamellae!!
    insert pas
    g_pas=0.001/(2*9.15*diam+2*30)
    e_pas=-85
}
}
obfunc connect2target() { localobj nc //$o1 target point process, optional $o2 returned NetCon
  node[nnode-1] nc = new NetCon(&v(1), $o1) // last axon node
  nc.threshold = -20
  if (numarg() == 2) { $o2 = nc } // for backward compatibility
  return nc
}


objref syn_
objref r
objref r1
objref file

proc synapses() {

  //Loading network parameters
  {xopen("SetNetworkSize.hoc")}

  //SYNAPSES
  r=new Random($1)
  r1=new Random($1)


  //EXCITATORY SYNAPSES
  mean =0
  for i=0,FromAll_IAf_ToOne_MN-1{
      //POISSON LIKE SPATIAL DISTRUBUTION OF SYNAPTIC BOUTONS

      // Since we have 5 synaptic bouton for fiber a is the mean of 5 random positioned synapses
      temp=r.poisson(4)
      for j=1,5{ // mean over 5 synapses
        temp = r.repick()
        a+=temp
      }
      a = int(a/5)-2
      if (a<0) {a=0}
      if (a>ndend) {a=ndend}

      mean+=a
      b=r1.uniform(0,1)


      dendrite[a] syn_ = new ExpSyn(b)  synlist.append(syn_) /* E */
      syn_.tau = 0.5
	   syn_.e=0
  }
  mean/=FromAll_IAf_ToOne_MN

  for i=0,FromAll_EXIN_ToOne_MN-1{
      //POISSON RANDOM SYNAPTIC POSITIONING
      a=r.poisson(4.2)
      while(a<2 || a>ndend){
              a=r.repick()
          }
      a=a-2  //SHIFTS FROM 0 TO NDEND
      b=r1.uniform(0,1)

      dendrite[int(a)] syn_ = new ExpSyn(b)  synlist.append(syn_) /* E */
      syn_.tau = 0.5
      syn_.e=0
  }
  //INHIBITORY SYNAPSES FROM IA (Int Fire)
  for i=0,FromAll_IAint_ToOne_MN-1{
    soma[0] syn_ = new Exp2Syn(0.5)  synlist.append(syn_)  /* I */
    syn_.tau1 = 1.5
    syn_.tau2 = 2
    syn_.e = -75
  }

  //EES EFFECT
  node[3] syn_ = new ExpSyn(0.5)  synlist.append(syn_)   /* E */
  syn_.tau = 0.1
  syn_.e= 50
}

func is_art() {
 return 0 }

proc position() {
    soma for i = 0, n3d()-1 {
        pt3dchange(i, $1+x3d(i), $2+y3d(i), $3+z3d(i), diam3d(i))
    }
}

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