title: The influence of synaptic size on AMPA receptor activation: a Monte Carlo model.
abstract: Physiological and electron microscope studies have shown that synapses are functionally and morphologically heterogeneous and that variations in size of synaptic junctions are related to characteristics such as release probability and density of postsynaptic AMPA receptors. The present article focuses on how these morphological variations impact synaptic transmission. We based our study on Monte Carlo computational simulations of simplified model synapses whose morphological features have been extracted from hundreds of actual synaptic junctions reconstructed by three-dimensional electron microscopy. We have examined the effects that parameters such as synaptic size or density of AMPA receptors have on the number of receptors that open after release of a single synaptic vesicle. Our results indicate that the maximum number of receptors that will open after the release of a single synaptic vesicle may show a ten-fold variation in the whole population of synapses. When individual synapses are considered, there is also a stochastical variability that is maximal in small synapses with low numbers of receptors. The number of postsynaptic receptors and the size of the synaptic junction are the most influential parameters, while the packing density of receptors or the concentration of extrasynaptic transporters have little or no influence on the opening of AMPA receptors.
authors.affiliation: Departamento de Arquitectura y Tecnología de Sistemas Informáticos, Facultad de Informatica, Universidad Politecnica de Madrid, Madrid, Spain.
authors.forename: Jesus
authors.initials: J
authors.lastname: Montes
authors.affiliation: Departamento de Arquitectura y Tecnología de Sistemas Informáticos, Facultad de Informatica, Universidad Politecnica de Madrid, Madrid, Spain.
authors.forename: Jose M
authors.initials: JM
authors.lastname: Peña
authors.affiliation: Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, Madrid, Spain; Instituto Cajal, Consejo Superior de Investigaciones Científicas, Madrid, Spain.
authors.forename: Javier
authors.initials: J
authors.lastname: DeFelipe
authors.affiliation: Instituto Cajal, Consejo Superior de Investigaciones Científicas, Madrid, Spain.
authors.forename: Oscar
authors.initials: O
authors.lastname: Herreras
authors.affiliation: Departamento de Arquitectura y Tecnología de Sistemas Informáticos, Facultad de Informatica, Universidad Politecnica de Madrid, Madrid, Spain; Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, Madrid, Spain.
authors.forename: Angel
authors.initials: A
authors.lastname: Merchan-Perez
mesh_terms: D003198:Computer Simulation; D006801:Humans; D021621:Imaging, Three-Dimensional; D008854:Microscopy, Electron; D009010:Monte Carlo Method; D011336:Probability; D018091:Receptors, AMPA / Q000378:metabolism*; D012044:Regression Analysis; D015398:Signal Transduction; D013569:Synapses / Q000378:metabolism*; D009435:Synaptic Transmission; D013572:Synaptic Vesicles / Q000378:metabolism*
chemical_list: D018091:Receptors, AMPA