title: Synaptic democracy and vesicular transport in axons.
abstract: Synaptic democracy concerns the general problem of how regions of an axon or dendrite far from the cell body (soma) of a neuron can play an effective role in neuronal function. For example, stimulated synapses far from the soma are unlikely to influence the firing of a neuron unless some sort of active dendritic processing occurs. Analogously, the motor-driven transport of newly synthesized proteins from the soma to presynaptic targets along the axon tends to favor the delivery of resources to proximal synapses. Both of these phenomena reflect fundamental limitations of transport processes based on a localized source. In this Letter, we show that a more democratic distribution of proteins along an axon can be achieved by making the transport process less efficient. This involves two components: bidirectional or "stop-and-go" motor transport (which can be modeled in terms of advection-diffusion), and reversible interactions between motor-cargo complexes and synaptic targets. Both of these features have recently been observed experimentally. Our model suggests that, just as in human societies, there needs to be a balance between "efficiency" and "equality".
authors.affiliation: Department of Mathematics, University of Utah, 155 South 1400 East, Salt Lake City, Utah 84112, USA.
authors.forename: Paul C
authors.initials: PC
authors.lastname: Bressloff
authors.affiliation: Department of Mathematics, University of Utah, 155 South 1400 East, Salt Lake City, Utah 84112, USA.
authors.forename: Ethan
authors.initials: E
authors.lastname: Levien
mesh_terms: D001369:Axons / Q000378:metabolism / Q000502:physiology*; D008959:Models, Neurological; D020409:Molecular Motor Proteins / Q000378:metabolism; D009474:Neurons / Q000378:metabolism / Q000502:physiology; D021381:Protein Transport; D013569:Synapses / Q000378:metabolism / Q000502:physiology*; D013572:Synaptic Vesicles / Q000378:metabolism*
chemical_list: D020409:Molecular Motor Proteins