Modelling reduced excitability in aged CA1 neurons as a Ca-dependent process (Markaki et al. 2005)

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Accession:119266
"We use a multi-compartmental model of a CA1 pyramidal cell to study changes in hippocampal excitability that result from aging-induced alterations in calcium-dependent membrane mechanisms. The model incorporates N- and L-type calcium channels which are respectively coupled to fast and slow afterhyperpolarization potassium channels. Model parameters are calibrated using physiological data. Computer simulations reproduce the decreased excitability of aged CA1 cells, which results from increased internal calcium accumulation, subsequently larger postburst slow afterhyperpolarization, and enhanced spike frequency adaptation. We find that aging-induced alterations in CA1 excitability can be modelled with simple coupling mechanisms that selectively link specific types of calcium channels to specific calcium-dependent potassium channels."
Reference:
1 . Markaki M, Orphanoudakis S, Poirazi P (2005) Modelling reduced excitability in aged CA1 neurons as a calcium-dependent process Neurocomputing 65-66:305-314
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: Hippocampus;
Cell Type(s): Hippocampus CA1 pyramidal cell;
Channel(s): I Na,p; I Na,t; I L high threshold; I N; I A; I K; I M; I K,Ca; I R;
Gap Junctions:
Receptor(s):
Gene(s):
Transmitter(s):
Simulation Environment: NEURON;
Model Concept(s): Activity Patterns; Aging/Alzheimer`s;
Implementer(s):
Search NeuronDB for information about:  Hippocampus CA1 pyramidal cell; I Na,p; I Na,t; I L high threshold; I N; I A; I K; I M; I K,Ca; I R;
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CA1_Aged
lib
basic_graphics.hoc *
basic-graphics.hoc *
choose-secs.hoc *
current-balance.hoc
cut-sections.hoc *
deduce-ratio.hoc *
find-gmax.hoc *
GABA_shiftsyn.hoc *
GABA_shiftsyn_bg.hoc *
ken.h *
map-segments-to-3d.hoc *
maxmin.hoc *
mod_func.c *
newshiftsyn *
newshiftsyn.c *
num-rec.h *
salloc.hoc *
shiftsyn-init_bg.hoc *
shiftsyn-initA.hoc *
spikecount.hoc *
tune-epsps.hoc *
vector-distance.hoc *
verbose-system.hoc *
                            
// Given a reference point (ie, soma), an apex point, and a point of
// interest, (POI), this function returns the distance from the reference point to
// the POI. These three points are vectors with x,y,z as their values
// written by Terrence Brannon, last modified by Yiota Poirazi, July 2001, poirazi@LNC.usc.edu

objref RP, POI, APEX

proc pvec() {
  printf("%s: \t", $s1)
  $o2.printf("%f ")
}

proc pvecs() {
  pvec("RP", RP)
  pvec("APEX",APEX)
  pvec("POI",POI)
}

proc clear_vecs() {
  RP=new Vector()
  APEX=new Vector()
  POI=new Vector()
}

objref vhold
vhold=new Vector()

func vector_distance() { local adjustment
//  print "func vector_distance() {"

  clear_vecs()
  
  RP=$o1.c
  APEX=$o2.c
  POI=$o3.c
  adjustment = $4

//  pvecs()

  // Subtract Psoma: Qapex = Papex - Psoma. Therefore Qsoma=0,0,0

  APEX.sub(RP)
  POI.sub(RP)
    RP.sub(RP)

//    pvecs()

  // Normalize Qapex, Creating Uapex

  vhold=APEX.c
  vhold.mul(vhold)
  APEX_BAR=sqrt(vhold.sum())

//  printf("APEX_BAR: %f\n", APEX_BAR)

  APEX.div(APEX_BAR)

//  pvec("UAPEX", APEX)

  // Find length of projection of Qdend onto Uapex

  H = POI.dot(APEX) + adjustment
  
  H=abs(H)

  return(H)
}

objref fvd_vec
strdef fvd_str
func find_vector_distance() {

  fvd_vec=new Vector()
  sprint(fvd_str, "access %s", $s1)
  execute1(fvd_str)
  
  vcreate2(fvd_vec,0)
  
  return(vector_distance(vRP,vAPEX,fvd_vec,adjustment))
}

func find_vector_distance_precise() {

  fvd_vec=new Vector()
  sprint(fvd_str, "access %s", $s1)
  execute1(fvd_str)
  
  vcreate3(fvd_vec,$2)
  
  return(vector_distance(vRP,vAPEX,fvd_vec,adjustment))
}

proc vcreate() {
  $o1.append(x3d(0))
  $o1.append(y3d(0))
  $o1.append(z3d(0))
}

proc vcreate2() {
  $o1.append(x3d($2))
  $o1.append(y3d($2))
  $o1.append(z3d($2))
}

proc vcreate3() {
  $o1.append(x_d3($2))
  $o1.append(y_d3($2))
  $o1.append(z_d3($2))
}

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