The diffusional properties of dendrites depend on the density of dendritic spines

Authors

  • Fidel Santamaria,

    1. Biology Department and Neurosciences Institute, The University of Texas at San Antonio, One UTSA Circle, San Antonio, TX 78249, USA
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  • Stefan Wils,

    1. Computational Neuroscience Unit, Okinawa Institute of Science and Technology, Okinawa, Japan
    2. Laboratory of Theoretical Neurobiology, University of Antwerp, Antwerp, Belgium
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  • Erik De Schutter,

    1. Computational Neuroscience Unit, Okinawa Institute of Science and Technology, Okinawa, Japan
    2. Laboratory of Theoretical Neurobiology, University of Antwerp, Antwerp, Belgium
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  • George J. Augustine

    1. Center for Functional Connectomics, Korea Institute of Science and Technology, Seongbukgu, Seoul, Korea
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Fidel Santamaria, as above.
E-mail: fidel.santamaria@utsa.edu

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 (dw) 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 dw 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.

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