title: Impairments in precision, rather than spatial strategy, characterize performance on the virtual Morris Water Maze: A case study.
abstract: Damage to the medial temporal lobes produces profound amnesia, greatly impairing the ability of patients to learn about new associations and events. While studies in rodents suggest a strong link between damage to the hippocampus and the ability to navigate using distal landmarks in a spatial environment, the connection between navigation and memory in humans remains less clear. Past studies on human navigation have provided mixed findings about whether patients with damage to the medial temporal lobes can successfully acquire and navigate new spatial environments, possibly due, in part, to issues related to patient demographics and characterization of medial temporal lobe damage. Here, we report findings from a young, high functioning patient who suffered severe medial temporal lobe damage. Although the patient is densely amnestic, her ability to acquire and utilize new, but coarse, spatial "maps" appears largely intact. Specifically, a novel computational analysis focused on the precision of her spatial search revealed a significant deficit in spatial precision rather than spatial search strategy. These findings argue that an intact hippocampus in humans is not necessary for representing multiple external landmarks during spatial navigation of new environments. We suggest instead that the human hippocampus may store and represent complex high-resolution bindings of features in the environment as part of a larger role in perception, memory, and navigation.
authors.affiliation: Department of Psychology, University of California, Davis, 1 Shields Ave, Davis, CA 95618, USA; Center for Neuroscience, University of California, Davis, 1 Shields Ave, Davis, CA 95618, USA.
authors.forename: Branden S
authors.initials: BS
authors.lastname: Kolarik
authors.affiliation: Department of Neurological Surgery, University of California, Davis, 4860 Y Street Suite 3740, Sacramento, CA 95817, USA.
authors.forename: Kiarash
authors.initials: K
authors.lastname: Shahlaie
authors.affiliation: Center for Neuroscience, University of California, Davis, 1 Shields Ave, Davis, CA 95618, USA.
authors.forename: Abdul
authors.initials: A
authors.lastname: Hassan
authors.affiliation: Department of Psychology, University of California, Davis, 1 Shields Ave, Davis, CA 95618, USA.
authors.forename: Alyssa A
authors.initials: AA
authors.lastname: Borders
authors.affiliation: Center for Neuroscience, University of California, Davis, 1 Shields Ave, Davis, CA 95618, USA.
authors.forename: Kyle C
authors.initials: KC
authors.lastname: Kaufman
authors.affiliation: Department of Neurological Surgery, University of California, Davis, 4860 Y Street Suite 3740, Sacramento, CA 95817, USA.
authors.forename: Gene
authors.initials: G
authors.lastname: Gurkoff
authors.affiliation: Department of Psychology, University of California, Davis, 1 Shields Ave, Davis, CA 95618, USA.
authors.forename: Andy P
authors.initials: AP
authors.lastname: Yonelinas
authors.affiliation: Department of Psychology, University of California, Davis, 1 Shields Ave, Davis, CA 95618, USA; Center for Neuroscience, University of California, Davis, 1 Shields Ave, Davis, CA 95618, USA. Electronic address: adekstrom@ucdavis.edu.
authors.forename: Arne D
authors.initials: AD
authors.lastname: Ekstrom
mesh_terms: D000328:Adult; D001930:Brain Injuries / Q000150:complications* / Q000473:pathology; D005260:Female; D006624:Hippocampus / Q000503:physiopathology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D018782:Maze Learning / Q000502:physiology*; D009483:Neuropsychological Tests; D010468:Perceptual Disorders / Q000209:etiology*; D011930:Reaction Time; D013028:Space Perception / Q000502:physiology*; D065854:Spatial Navigation / Q000502:physiology*; D014584:User-Computer Interface; D014706:Verbal Learning; D055815:Young Adult
keywords: Allocentric cognitive map; Hippocampus; MTL lesion; Memory; Morris Water Maze; Spatial memory