Physical regulation of dendritic spines
Various physical mechanisms regulate the strength of the synapse. The strength of a synaps is controlled by the concentration of membrane bound glutamate receptors at the synapse. The concentration of these receptors is balanced by active deposition in the head region, anchoring to scaffold proteins and lateral diffusion through the neck. Our theoretical study seeks to quantify the physical processes that are at heart of this synaptic strength regulation. We find that at the one hand, geometrical confinement and crowding, on the diffusion side, help sustain gradients in concentrations of receptors for very long times. At the other hand, an increased geometrical confinement requires an increased number of molecular motors to transport the receptor containing vesicles through the neck.
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References:
Barriers in the brain: resolving dendritic spine morphology and compartmentalization; M. Adrian, R. Kusters, C. Wierenga, C. Storm, C. Hoogenraad, L. Kapitein; Frontiers in Neuroanatomy, vol. 8, 142
Shape-induced asymmetric diffusion in dendritic spines allows efficient synaptic AMPA receptor trapping; R. Kusters, L. Kapitein, C. Hoogenraad, C. Storm; Biophysical Journal, vol. 105, 2743-2750
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Modeling the growth of dendritic spines
We model the early formation and maturation of dendritic spine and present a general framework that details the precise role of actin in directing the transitions between the various spine shapes. In the early stages of spine formation, the interplay between the elastic properties of the spine membrane and the protrusive forces generated in the actin cytoskeleton propels the incipient spine. In the maturation stage, actin remodeling in the form of the combined dynamics of branched and bundled actin is required to form mature, mushroom-like spines. We invoke Canham Helfrich formalism to provides us insights into the fundamental role of actin remodeling and polymerization forces during spine formation and maturation.
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Reference:
Actin remodeling and polymerization forces control dendritic spine morphology; C.A. Miermans, R. Kusters, C.C. Hoogenraad, C. Storm; Arxiv:1507.05071 (2015)
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