title: Small-Volume Effect Enables Robust, Sensitive, and Efficient Information Transfer in the Spine.
abstract: Why is the spine of a neuron so small that it can contain only small numbers of molecules and reactions inevitably become stochastic? We previously showed that, despite such noisy conditions, the spine exhibits robust, sensitive, and efficient features of information transfer using the probability of Ca2+increase; however, the mechanisms are unknown. In this study, we show that the small volume effect enables robust, sensitive, and efficient information transfer in the spine volume, but not in the cell volume. In the spine volume, the intrinsic noise in reactions becomes larger than the extrinsic noise of input, resulting in robust information transfer despite input fluctuation. In the spine volume, stochasticity makes the Ca2+increase occur with a lower intensity of input, causing higher sensitivity to lower intensity of input. The volume-dependency of information transfer increases its efficiency in the spine volume. Thus, we propose that the small-volume effect is the functional reason why the spine has to be so small.
authors.affiliation: Department of Biological Sciences, University of Tokyo, Bukyo-ku, Tokyo, Japan; Molecular Genetics Research Laboratory, Graduate School of Sciences, University of Tokyo, Bukyo-ku, Tokyo, Japan.
authors.forename: Masashi
authors.initials: M
authors.lastname: Fujii
authors.affiliation: Department of Biological Sciences, University of Tokyo, Bukyo-ku, Tokyo, Japan.
authors.forename: Kaoru
authors.initials: K
authors.lastname: Ohashi
authors.affiliation: Department of Neurosurgery, Graduate School of Medicine, University of Tokyo, Bukyo-ku, Tokyo, Japan.
authors.forename: Yasuaki
authors.initials: Y
authors.lastname: Karasawa
authors.affiliation: Department of Biological Sciences, University of Tokyo, Bukyo-ku, Tokyo, Japan.
authors.forename: Minori
authors.initials: M
authors.lastname: Hikichi
authors.affiliation: Department of Biological Sciences, University of Tokyo, Bukyo-ku, Tokyo, Japan; Molecular Genetics Research Laboratory, Graduate School of Sciences, University of Tokyo, Bukyo-ku, Tokyo, Japan; CREST, Japan Science and Technology Agency, Bunkyo-ku, Tokyo, Japan. Electronic address: skuroda@bs.s.u-tokyo.ac.jp.
authors.forename: Shinya
authors.initials: S
authors.lastname: Kuroda
mesh_terms: D002118:Calcium / Q000378:metabolism; D049229:Dendritic Spines / Q000378:metabolism*; D008959:Models, Neurological; D011689:Purkinje Cells / Q000166:cytology; D015398:Signal Transduction; D013269:Stochastic Processes
chemical_list: D002118:Calcium