title: Spatiotemporal dynamics of lesion-induced axonal sprouting and its relation to functional architecture of the cerebellum.
abstract: Neurodegenerative lesions induce sprouting of new collaterals from surviving axons, but the extent to which this form of axonal remodelling alters brain functional structure remains unclear. To understand how collateral sprouting proceeds in the adult brain, we imaged post-lesion sprouting of cerebellar climbing fibres (CFs) in mice using in vivo time-lapse microscopy. Here we show that newly sprouted CF collaterals innervate multiple Purkinje cells (PCs) over several months, with most innervations emerging at 3-4 weeks post lesion. Simultaneous imaging of cerebellar functional structure reveals that surviving CFs similarly innervate functionally relevant and non-relevant PCs, but have more synaptic area on PCs near the collateral origin than on distant PCs. These results suggest that newly sprouted axon collaterals do not preferentially innervate functionally relevant postsynaptic targets. Nonetheless, the spatial gradient of collateral innervation might help to loosely maintain functional synaptic circuits if functionally relevant neurons are clustered in the lesioned area.
authors.affiliation: Center for Learning and Memory, Department of Neuroscience, The University of Texas at Austin, 1 University Station Stop C7000, Austin, Texas 78712-0805, USA.
authors.forename: Matasha
authors.identifier: 0000-0003-1714-0424
authors.initials: M
authors.lastname: Dhar
authors.affiliation: Center for Learning and Memory, Department of Neuroscience, The University of Texas at Austin, 1 University Station Stop C7000, Austin, Texas 78712-0805, USA.
authors.forename: Joshua M
authors.initials: JM
authors.lastname: Brenner
authors.affiliation: Department of Cellular Neurobiology, Brain Research Institute, Niigata University, 1-757 Asahimachidori, Chuo-ku, Niigata 951-8585, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Sakimura
authors.affiliation: Department of Neurophysiology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Masanobu
authors.initials: M
authors.lastname: Kano
authors.affiliation: Center for Learning and Memory, Department of Neuroscience, The University of Texas at Austin, 1 University Station Stop C7000, Austin, Texas 78712-0805, USA.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Nishiyama
mesh_terms: D000818:Animals; D001369:Axons; D002531:Cerebellum / Q000166:cytology*; D008164:Luminescent Proteins / Q000378:metabolism; D051379:Mice; D008822:Mice, Transgenic; D009412:Nerve Fibers / Q000502:physiology; D009419:Nerve Tissue Proteins; D009473:Neuronal Plasticity; D009847:Olivary Nucleus / Q000166:cytology / Q000473:pathology; D062211:Spatio-Temporal Analysis
chemical_list: D008164:Luminescent Proteins; D009419:Nerve Tissue Proteins; C092565:zebrin I