title: Aging, spatial learning, and total synapse number in the rat CA1 stratum radiatum.
abstract: The aim of this study was to determine whether spatial learning deficits in aged rats are associated with a loss of hippocampal synapses. The Morris water maze task was used to assess the spatial learning capacity of young and aged rats and to attribute aged animals to learning-impaired and learning-unimpaired groups. The number of axospinous synapses in the entire volume of the CA1 stratum radiatum was estimated with unbiased stereological techniques. The results show that the total number of all axospinous synapses and of their perforated and nonperforated subtypes remains constant in the CA1 stratum radiatum of aged learning-impaired rats as compared to aged learning-unimpaired rats and to young adults. Thus, neither age-related deficits in spatial learning nor advanced chronological age are associated with a loss of axospinous synapses from the rat CA1 stratum radiatum.
authors.affiliation: Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, 303 East Chicago Avenue, Chicago, IL 60611, USA. yurig@northwestern.edu
authors.forename: Y
authors.initials: Y
authors.lastname: Geinisman
authors.forename: O
authors.initials: O
authors.lastname: Ganeshina
authors.forename: R
authors.initials: R
authors.lastname: Yoshida
authors.forename: R W
authors.initials: RW
authors.lastname: Berry
authors.forename: J F
authors.initials: JF
authors.lastname: Disterhoft
authors.forename: M
authors.initials: M
authors.lastname: Gallagher
mesh_terms: D000375:Aging / Q000473:pathology*; D000818:Animals; D002452:Cell Count; D003712:Dendrites / Q000473:pathology / Q000648:ultrastructure; D006624:Hippocampus / Q000473:pathology* / Q000503:physiopathology / Q000648:ultrastructure; D007859:Learning Disabilities / Q000473:pathology / Q000503:physiopathology; D008297:Male; D018782:Maze Learning / Q000502:physiology; D008569:Memory Disorders / Q000473:pathology* / Q000503:physiopathology; D008854:Microscopy, Electron; D009434:Neural Pathways / Q000473:pathology* / Q000648:ultrastructure; D017729:Presynaptic Terminals / Q000473:pathology / Q000648:ultrastructure; D051381:Rats; D020318:Rats, Long-Evans; D013569:Synapses / Q000473:pathology* / Q000648:ultrastructure