A kinetic model unifying presynaptic short-term facilitation and depression (Lee et al. 2009)

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"... Here, we propose a unified theory of synaptic short-term plasticity based on realistic yet tractable and testable model descriptions of the underlying intracellular biochemical processes. Analysis of the model equations leads to a closed-form solution of the resonance frequency, a function of several critical biophysical parameters, as the single key indicator of the propensity for synaptic facilitation or depression under repetitive stimuli. This integrative model is supported by a broad range of transient and frequency response experimental data including those from facilitating, depressing or mixed-mode synapses. ... the model provides the reasons behind the switching behavior between facilitation and depression observed in experiments. ..."
1 . Lee CC, Anton M, Poon CS, McRae GJ (2009) A kinetic model unifying presynaptic short-term facilitation and depression. J Comput Neurosci 26:459-73 [PubMed]
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Model Information (Click on a link to find other models with that property)
Model Type: Synapse;
Brain Region(s)/Organism:
Cell Type(s): Hippocampus CA1 pyramidal GLU cell; Cerebellum Purkinje GABA cell; Auditory nerve;
Channel(s): I Calcium;
Gap Junctions:
Receptor(s): AMPA;
Transmitter(s): Glutamate;
Simulation Environment: MATLAB; Simulink;
Model Concept(s): Synaptic Plasticity; Facilitation; Depression; Calcium dynamics;
Implementer(s): Lee, Chuang-Chung [chchlee at alum.mit.edu]; Anton, Mihai [mianton at mit.edu]; Poon, Chi-Sang [cpoon at mit.edu]; McRae, Gregory [mcrae at mit.edu];
Search NeuronDB for information about:  Hippocampus CA1 pyramidal GLU cell; Cerebellum Purkinje GABA cell; AMPA; I Calcium; Glutamate;
function [sys,x0] = mixture_presyn(time,x,u,flag,xinit)
%  This function transforms calcium currents into the flux of glutamate
%  It be used in a Simulink model as the component of an S Function block
%  Set the S Function name to mixture_presyn
%  The input vector is the calcium current (ICa)
%  The output vector consists of  
%  1  concentration of bound calcium (Ca)  as well as 
%  2  releasable vesicle ratio (Rrel) 
%  3  release probability (Prel)
%  4  the flux of neurotransmitter (dGlu/dt)

% Supplemental materials of "A Synaptic Model of Short Term Depression and 
% Facilitation"
% 10 Aug 2006 by Chuang-Chung Lee

% model parameters
zstates = 2;
zoutput = 4;
zinput = 1;

% reaction parameters with fixed values
Ca0=0.075e2; % calcium dynamics
krecov0=0.75E-2; % recovery rate constants
Prelmax=1; % release probability

if (abs(flag) == 1),  %return state derivates
  sys = zeros(zstates, 1);
  Ca = x(1); % conc. of bound calcium
  Rrel = x(2); % releasable vesicle ratio
  %species equations
  sys(1) = (1/TauCa)*(-Ca+Ca0+KCa*u); % conc. of bound calcium
  Prel = Prelmax*Ca^4/(Ca^4+Krel^4); % release probability
  krecov = krecov0+(krecovmax-krecov0)*Ca/(Ca+Krecov); % recovery rate
  sys(2) = krecov*(1-Rrel)- (Prel*Rrel*u); % releasable vesicle ratio

elseif flag == 3,	% return system outputs
  sys(1:2) = x;
  Ca = x(1); % conc. of bound calcium
  Rrel = x(2); % releasable vesicle ratio
  Prel = Prelmax*Ca^4/(Ca^4+Krel^4); % release probability
  sys(3)= Prel;
  sys(4) = (Rrel*Prel*u)*9.5e6;  %dGlu/dt
elseif flag == 0,	% initial conditions, etc
  sys = [zstates, 0, zoutput, zinput, 0, 1];
  if nargin < 5
    x0(1) = 0.075e2;
    x0(2) = 1;
    x0 = xinit;