title: Stochasticity in Ca2+ increase in spines enables robust and sensitive information coding.
abstract: A dendritic spine is a very small structure (∼0.1 µm3) of a neuron that processes input timing information. Why are spines so small? Here, we provide functional reasons; the size of spines is optimal for information coding. Spines code input timing information by the probability of Ca2+ increases, which makes robust and sensitive information coding possible. We created a stochastic simulation model of input timing-dependent Ca2+ increases in a cerebellar Purkinje cell's spine. Spines used probability coding of Ca2+ increases rather than amplitude coding for input timing detection via stochastic facilitation by utilizing the small number of molecules in a spine volume, where information per volume appeared optimal. Probability coding of Ca2+ increases in a spine volume was more robust against input fluctuation and more sensitive to input numbers than amplitude coding of Ca2+ increases in a cell volume. Thus, stochasticity is a strategy by which neurons robustly and sensitively code information.
authors.affiliation: Undergraduate Department of Bioinformatics and Systems Biology, University of Tokyo, Bunkyo-ku, Tokyo, Japan.
authors.forename: Takuya
authors.initials: T
authors.lastname: Koumura
authors.affiliation: Department of Biophysics and Biochemistry, Graduate School of Science, University of Tokyo, Bunkyo-ku, Tokyo, Japan.
authors.forename: Hidetoshi
authors.initials: H
authors.lastname: Urakubo
authors.affiliation: Department of Biophysics and Biochemistry, Graduate School of Science, University of Tokyo, Bunkyo-ku, Tokyo, Japan.
authors.forename: Kaoru
authors.initials: K
authors.lastname: Ohashi
authors.affiliation: Department of Biophysics and Biochemistry, Graduate School of Science, University of Tokyo, Bunkyo-ku, Tokyo, Japan.
authors.forename: Masashi
authors.initials: M
authors.lastname: Fujii
authors.affiliation: Undergraduate Department of Bioinformatics and Systems Biology, University of Tokyo, Bunkyo-ku, Tokyo, Japan; Department of Biophysics and Biochemistry, Graduate School of Science, University of Tokyo, Bunkyo-ku, Tokyo, Japan.
authors.forename: Shinya
authors.initials: S
authors.lastname: Kuroda
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D049229:Dendritic Spines / Q000502:physiology*; D054351:Electrical Synapses / Q000502:physiology; D008297:Male; D051379:Mice; D008959:Models, Neurological; D009474:Neurons; D011689:Purkinje Cells / Q000502:physiology*; D013269:Stochastic Processes
chemical_list: D002118:Calcium