BIOPHYSICAL THEORY AND MODELING |
Modeling synaptic dynamics driven by receptor lateral
diffusion
David Holcman 1* and Antoine Triller 2
1 Weizmann Institute of Science
2 Ecole Normale Superieure
* To whom correspondence should be addressed. E-mail: david.holcman{at}weizmann.ac.il.
Submitted on January 28, 2006
Revised on April 6, 2006
Accepted on 16 June 2006
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Abstract |
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The synaptic weight between a pre- and a postsynaptic neuron depends in part on the number of postsynaptic receptors. On the surface of neurons, receptors traffic by random motion in and out from a microstructure called the Postsynaptic Density (PSD). In the PSD, receptors can be stabilized at the membrane when they bind to scaffolding proteins. We propose a mathematical model to compute the postsynaptic counterpart of the synaptic weight based on receptor trafficking. We take into account the receptor fluxes at the PSD, which can be regulated by neuronal activity and the interactions of receptors with the scaffolding molecules. Using a Markovian approach, we estimate the mean and the fluctuations of the number of bound receptors. When the number of receptors is large, a deterministic system is also derived. These equations can be used to fit FRAP experiments to determine in living neurons, the chemical binding constants of receptors to scaffolding molecules at synapses.
Key Words:
Markov chain, diffusion, mathematical modeling, receptors, synapses, trafficking
