title: The hippocampus is involved in mental navigation for a recently learned, but not a highly familiar environment: a longitudinal fMRI study.
abstract: Functional magnetic resonance imaging (MRI) was used to investigate the hypothesis that memory for a large-scale environment is initially dependent on the hippocampus but is later supported by extra-hippocampal structures (e.g., precuneus, posterior parahippocampal cortex, and lingual gyrus) once the environment is well-learned. Participants were scanned during mental navigation tasks initially when they were newly arrived to the city of Toronto, and later after having lived and navigated within the city for 1 yr. In the first session, activation was observed in the right hippocampus, left precuneus, and postcentral gyrus. The second session revealed activation in the caudate and lateral temporal cortex, but not in the right hippocampus; additional activation was instead observed in the posterior parahippocampal cortex, lingual gyrus, and precuneus. These findings suggest that the right hippocampus is required for the acquisition of new spatial information but is not needed to represent this information when the environment is highly familiar.
authors.affiliation: Department of Psychology, University of Toronto, Toronto, Ontario, Canada. marnie.hirshhorn@utoronto.ca
authors.forename: Marnie
authors.initials: M
authors.lastname: Hirshhorn
authors.forename: Cheryl
authors.initials: C
authors.lastname: Grady
authors.forename: R Shayna
authors.initials: RS
authors.lastname: Rosenbaum
authors.forename: Gordon
authors.initials: G
authors.lastname: Winocur
authors.forename: Morris
authors.initials: M
authors.lastname: Moscovitch
mesh_terms: D000328:Adult; D001931:Brain Mapping; D005260:Female; D006624:Hippocampus / Q000502:physiology*; D006801:Humans; D007361:Intelligence Tests; D007858:Learning / Q000502:physiology*; D008137:Longitudinal Studies; D008279:Magnetic Resonance Imaging; D008297:Male; D008568:Memory / Q000502:physiology; D019579:Neocortex / Q000502:physiology; D013028:Space Perception / Q000502:physiology; D013647:Task Performance and Analysis; D013702:Temporal Lobe / Q000502:physiology; D055815:Young Adult