Mathematical Biology Seminar
Paul Bressloff
Department of Mathematics, University of Utah
Wednesday November 15, 2006
3:05pm in LCB 215
``Protein receptor trafficking
across multiple synapses''
We present a mathematical model of AMPA receptor
trafficking between multiple dendritic spines distributed along the
surface of a dendrite. Receptors undergo lateral diffusion within
the dendritic surface membrane, with each spine acting as a
spatially-localized trap where receptors can bind to scaffolding
proteins or be internalized through endocytosis. We demonstrate
that
the lateral diffusion of AMPA receptors within the dendritic
membrane generates a form of heterosynaptic competition whose
strength depends on spine geometry and membrane diffusivity. We also
show how lateral diffusion provides a mechanism for synaptic scaling,
which is thought to be important in the homeostatic control of
synaptic
plasticity. Finally, we
explore the consequences of assuming that receptor exocytosis
occurs
only at the soma, which is a topic of some controversy between
experimentalists. In particular, we show that somatic exocytosis
can supply distal synapses with receptors only when the properties
of the spines/synapses vary with distance from the soma, and that
the mean time required for receptors leaving the soma to reach even
a few hundred micrometers from the soma is several orders of
magnitude
longer than the estimated metabolic half-life of an AMPA receptor.
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Mathematical Biology Program
Department of Mathematics
University of Utah
155 South 1400 East Room 233
Salt Lake City, UT 84112
rasmusse@math.utah.edu
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