title: Map reading, navigating from maps, and the medial temporal lobe.
abstract: We administered map-reading tasks in which participants navigated an array of marks on the floor by following paths on hand-held maps that made up to nine turns. The burden on memory was minimal because the map was always available. Nevertheless, because the map was held in a fixed position in relation to the body, spatial computations were continually needed to transform map coordinates into geographical coordinates as participants followed the maps. Patients with lesions limited to the hippocampus (n = 5) performed similar to controls at all path lengths (experiment 1). They were also intact at executing single moves to an adjacent location, even when trials began by facing in a direction that put the map coordinates and geographical coordinates into conflict (experiment 2). By contrast, one patient with large medial temporal lobe (MTL) lesions performed poorly overall in experiment 1 and poorly in experiment 2 when trials began by facing in the direction that placed the map coordinates and geographical coordinates in maximal conflict. Directly after testing, all patients were impaired at remembering factual details about the task. The findings suggest that the hippocampus is not needed to carry out the spatial computations needed for map reading and navigating from maps. The impairment in map reading associated with large MTL lesions may depend on damage in or near the parahippocampal cortex.
authors.affiliation: Veterans Affairs San Diego Healthcare System, San Diego, CA 92161.|Department of Psychiatry, University of California, San Diego, La Jolla, CA 92093.
authors.forename: Zhisen J
authors.initials: ZJ
authors.lastname: Urgolites
authors.affiliation: Department of Neurobiology and Behavior, University of California, Irvine, CA 92697.
authors.forename: Soyun
authors.initials: S
authors.lastname: Kim
authors.affiliation: Department of Psychology, Brigham Young University, Provo, UT 84143.|Neuroscience Center, Brigham Young University, Provo, UT 84143.|Department of Medicine, Pulmonary and Critical Care Division, Intermountain Medical Center, Murray, UT 84143.
authors.forename: Ramona O
authors.initials: RO
authors.lastname: Hopkins
authors.affiliation: Veterans Affairs San Diego Healthcare System, San Diego, CA 92161; lsquire@ucsd.edu.|Department of Psychiatry, University of California, San Diego, La Jolla, CA 92093.|Department of Neurosciences, University of California, San Diego, La Jolla, CA 92093.|Department of Psychology, University of California, San Diego, La Jolla, CA 92093.
authors.forename: Larry R
authors.initials: LR
authors.lastname: Squire
mesh_terms: D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D005260:Female; D006624:Hippocampus / Q000473:pathology / Q000503:physiopathology; D006801:Humans; D008297:Male; D008377:Maps as Topic; D008568:Memory; D008569:Memory Disorders / Q000473:pathology / Q000503:physiopathology* / Q000523:psychology*; D008875:Middle Aged; D009483:Neuropsychological Tests; D011932:Reading; D065854:Spatial Navigation / Q000502:physiology*; D013647:Task Performance and Analysis; D013702:Temporal Lobe / Q000473:pathology / Q000503:physiopathology*
keywords: hippocampus; memory; spatial navigation