title: Spine formation pattern of adult-born neurons is differentially modulated by the induction timing and location of hippocampal plasticity.
abstract: In the adult hippocampus dentate gyrus (DG), newly born neurons are functionally integrated into existing circuits and play important roles in hippocampus-dependent memory. However, it remains unclear how neural plasticity regulates the integration pattern of new neurons into preexisting circuits. Because dendritic spines are major postsynaptic sites for excitatory inputs, spines of new neurons were visualized by retrovirus-mediated labeling to evaluate integration. Long-term potentiation (LTP) was induced at 12, 16, or 21 days postinfection (dpi), at which time new neurons have no, few, or many spines, respectively. The spine expression patterns were investigated at one or two weeks after LTP induction. Induction at 12 dpi increased later spinogenesis, although the new neurons at 12 dpi didn't respond to the stimulus for LTP induction. Induction at 21 dpi transiently mediated spine enlargement. Surprisingly, LTP induction at 16 dpi reduced the spine density of new neurons. All LTP-mediated changes specifically appeared within the LTP-induced layer. Therefore, neural plasticity differentially regulates the integration of new neurons into the activated circuit, dependent on their developmental stage. Consequently, new neurons at different developmental stages may play distinct roles in processing the acquired information by modulating the connectivity of activated circuits via their integration.
authors.affiliation: Department of Biochemistry, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Sugitani, Toyama, Japan.
authors.forename: Noriaki
authors.initials: N
authors.lastname: Ohkawa
authors.forename: Yoshito
authors.initials: Y
authors.lastname: Saitoh
authors.forename: Eri
authors.initials: E
authors.lastname: Tokunaga
authors.forename: Itsuko
authors.initials: I
authors.lastname: Nihonmatsu
authors.forename: Fumiko
authors.initials: F
authors.lastname: Ozawa
authors.forename: Akiko
authors.initials: A
authors.lastname: Murayama
authors.forename: Fumi
authors.initials: F
authors.lastname: Shibata
authors.forename: Toshio
authors.initials: T
authors.lastname: Kitamura
authors.forename: Kaoru
authors.initials: K
authors.lastname: Inokuchi
mesh_terms: D000818:Animals; D049229:Dendritic Spines / Q000378:metabolism / Q000648:ultrastructure*; D018891:Dentate Gyrus / Q000502:physiology; D006624:Hippocampus / Q000502:physiology*; D017774:Long-Term Potentiation; D008297:Male; D009473:Neuronal Plasticity / Q000502:physiology*; D009474:Neurons / Q000166:cytology* / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D016194:Receptors, N-Methyl-D-Aspartate / Q000378:metabolism
chemical_list: D016194:Receptors, N-Methyl-D-Aspartate