title: Spatial memory training induces morphological changes detected by manganese-enhanced MRI in the hippocampal CA3 mossy fiber terminal zone.
abstract: Hippocampal mossy fibers (MFs) can show plasticity of their axon terminal arbor consequent to learning a spatial memory task. Such plasticity is seen as translaminar sprouting from the stratum lucidum (SL) of CA3 into the stratum pyramidale (SP) and the stratum oriens (SO). However, the functional role of this presynaptic remodeling is still obscure. In vivo imaging that allows longitudinal observation of such remodeling could provide a deeper understanding of this presynaptic growth phenomenon as it occurs over time. Here we used manganese-enhanced magnetic resonance imaging (MEMRI), which shows a high-contrast area that co-localizes with the MFs. This technique was applied in the detection of learning-induced MF plasticity in two strains of rats. Quantitative analysis of a series of sections in the rostral dorsal hippocampus showed increases in the CA3a' area in MEMRI of trained Wistar rats consistent with the increased SO+SP area seen in the Timm's staining. MF plasticity was not seen in the trained Lister-Hooded rats in either MEMRI or in Timm's staining. This indicates the potential of MEMRI for revealing neuro-architectures and plasticity of the hippocampal MF system in vivo in longitudinal studies.
authors.affiliation: Department of Biological Sciences, National University of Singapore, Singapore.
authors.forename: Binbin
authors.initials: B
authors.lastname: Zhang
authors.affiliation: Magnetic Resonance Imaging Group, Singapore Bioimaging Consortium, A*STAR, Singapore; Department of Physiology, National University of Singapore, Singapore. Electronic address: kaichuang@gmail.com.
authors.forename: Kai-Hsiang
authors.initials: KH
authors.lastname: Chuang
authors.affiliation: Magnetic Resonance Imaging Group, Singapore Bioimaging Consortium, A*STAR, Singapore.
authors.forename: Ci'en
authors.initials: C
authors.lastname: Tjio
authors.affiliation: Magnetic Resonance Imaging Group, Singapore Bioimaging Consortium, A*STAR, Singapore.
authors.forename: Way Cherng
authors.initials: WC
authors.lastname: Chen
authors.affiliation: NUSNNI-Nanocore Institute, T-Lab Level 11, National University of Singapore, 5A Engineering Drive 1, Singapore.
authors.forename: Fwu-Shan
authors.initials: FS
authors.lastname: Sheu
authors.affiliation: Psychology, Neurobiology and Physiology, Northwestern University, Evanston, IL, USA; Physiology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA. Electronic address: aryeh@northwestern.edu.
authors.forename: Aryeh
authors.initials: A
authors.lastname: Routtenberg
mesh_terms: D000818:Animals; D001931:Brain Mapping / Q000379:methods*; D056654:CA3 Region, Hippocampal / Q000166:cytology* / Q000502:physiology; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008345:Manganese; D018782:Maze Learning / Q000502:physiology; D019599:Mossy Fibers, Hippocampal / Q000502:physiology / Q000648:ultrastructure*; D009473:Neuronal Plasticity / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D065852:Spatial Memory / Q000502:physiology*
chemical_list: D008345:Manganese
keywords: Hippocampal mossy fibers; MRI; Memory; Presynaptic plasticity; Spatial learning; Water maze