title: The diffusional properties of dendrites depend on the density of dendritic spines.
abstract: We combined computational modeling and experimental measurements to determine the influence of dendritic structure on the diffusion of intracellular chemical signals in mouse cerebellar Purkinje cells and hippocamal CA1 pyramidal cells. Modeling predicts that molecular trapping by dendritic spines causes diffusion along spiny dendrites to be anomalous and that the value of the anomalous exponent (d(w) ) is proportional to spine density in both cell types. To test these predictions we combined the local photorelease of an inert dye, rhodamine dextran, with two-photon fluorescence imaging to track diffusion along dendrites. Our results show that anomalous diffusion is present in spiny dendrites of both cell types. Further, the anomalous exponent is linearly related to the density of spines in pyramidal cells and d(w) in Purkinje cells is consistent with such a relationship. We conclude that anomalous diffusion occurs in the dendrites of multiple types of neurons. Because spine density is dynamic and depends on neuronal activity, the degree of anomalous diffusion induced by spines can dynamically regulate the movement of molecules along dendrites.
authors.affiliation: Biology Department and Neurosciences Institute, The University of Texas at San Antonio, One UTSA Circle, San Antonio, TX 78249, USA. fidel.santamaria@utsa.edu
authors.forename: Fidel
authors.initials: F
authors.lastname: Santamaria
authors.forename: Stefan
authors.initials: S
authors.lastname: Wils
authors.forename: Erik
authors.initials: E
authors.lastname: De Schutter
authors.forename: George J
authors.initials: GJ
authors.lastname: Augustine
mesh_terms: D000818:Animals; D003198:Computer Simulation; D003712:Dendrites / Q000737:chemistry / Q000378:metabolism; D049229:Dendritic Spines / Q000737:chemistry* / Q000378:metabolism; D004058:Diffusion; D006624:Hippocampus / Q000378:metabolism; D051379:Mice; D008958:Models, Molecular; D008959:Models, Neurological; D018408:Patch-Clamp Techniques; D011689:Purkinje Cells / Q000737:chemistry* / Q000378:metabolism; D017966:Pyramidal Cells / Q000737:chemistry* / Q000378:metabolism; D015398:Signal Transduction