title: Visuo-spatial memory deficits following medial temporal lobe damage: A comparison of three patient groups.
abstract: The contributions of the hippocampal formation and adjacent regions of the medial temporal lobe (MTL) to memory are still a matter of debate. It is currently unclear, to what extent discrepancies between previous human lesion studies may have been caused by the choice of distinct patient models of MTL dysfunction, as disorders affecting this region differ in selectivity, laterality and mechanisms of post-lesional compensation. Here, we investigated the performance of three distinct patient groups with lesions to the MTL with a battery of visuo-spatial short-term memory tasks. Thirty-one subjects with either unilateral damage to the MTL (postsurgical lesions following resection of a benign brain tumor, 6 right-sided lesions, 5 left) or bilateral damage (10 post-encephalitic lesions, 10 post-anoxic lesions) performed a series of tasks requiring short-term memory of colors, locations or color-location associations. We have shown previously that performance in the association task critically depends on hippocampal integrity. Patients with postsurgical damage of the MTL showed deficient performance in the association task, but performed normally in color and location tasks. Patients with left-sided lesions were almost as impaired as patients with right-sided lesions. Patients with bilateral post-encephalitic lesions showed comparable damage to MTL sub-regions and performed similarly to patients with postsurgical lesions in the association task. However, post-encephalitic patients showed additional impairments in the non-associative color and location tasks. A strikingly similar pattern of deficits was observed in post-anoxic patients. These results suggest a distinct cerebral organization of associative and non-associative short-term memory that was differentially affected in the three patient groups. Thus, while all patient groups may provide appropriate models of medial temporal lobe dysfunction in associative visuo-spatial short-term memory, additional deficits in non-associative memory tasks likely reflect damage of regions outside the MTL. Importantly, the choice of a patient model in human lesion studies of the MTL significantly influences overall performance patterns in visuo-spatial memory tasks.
authors.affiliation: Department of Neurology, Charité - Universitätsmedizin Berlin, Berlin, Germany.
authors.forename: Nazli
authors.initials: N
authors.lastname: Esfahani-Bayerl
authors.affiliation: Department of Neurology, Charité - Universitätsmedizin Berlin, Berlin, Germany; Berlin School of Mind and Brain, Humboldt-Universität, Berlin, Germany.
authors.forename: Carsten
authors.initials: C
authors.lastname: Finke
authors.affiliation: Department of Neurology, Charité - Universitätsmedizin Berlin, Berlin, Germany.
authors.forename: Mischa
authors.initials: M
authors.lastname: Braun
authors.affiliation: Institute of Cognitive Neurology and Dementia Research, Otto-von-Guericke University Magdeburg, Magdeburg, Germany; German Center for Neurodegenerative Diseases (DZNE) Site, Magdeburg, Germany; Institute of Cognitive Neuroscience, University College London, London, United Kingdom.
authors.forename: Emrah
authors.initials: E
authors.lastname: Düzel
authors.affiliation: Department of Education and Psychology, Freie Universität Berlin, Berlin, Germany; Cluster of Excellence "Languages of Emotion", Freie Universität Berlin, Berlin, Germany.
authors.forename: Hauke R
authors.initials: HR
authors.lastname: Heekeren
authors.affiliation: Department of Neurology, Charité - Universitätsmedizin Berlin, Berlin, Germany; Epilepsy-Center Berlin-Brandenburg, Evangelisches Krankenhaus Königin Elisabeth Herzberge, Berlin, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Holtkamp
authors.affiliation: Department of Nephrology and Medical Intensive Care Medicine, Charité - Universitätsmedizin Berlin, Berlin, Germany.
authors.forename: Dietrich
authors.initials: D
authors.lastname: Hasper
authors.affiliation: Department of Nephrology and Medical Intensive Care Medicine, Charité - Universitätsmedizin Berlin, Berlin, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Storm
authors.affiliation: Department of Neurology, Charité - Universitätsmedizin Berlin, Berlin, Germany. Electronic address: christoph.ploner@charite.de.
authors.forename: Christoph J
authors.initials: CJ
authors.lastname: Ploner
mesh_terms: D000328:Adult; D000368:Aged; D001930:Brain Injuries / Q000150:complications* / Q000209:etiology / Q000473:pathology*; D002648:Child; D003118:Color Perception / Q000502:physiology; D020803:Encephalitis, Herpes Simplex / Q000150:complications; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D002534:Hypoxia, Brain / Q000150:complications; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008569:Memory Disorders / Q000209:etiology*; D008570:Memory, Short-Term / Q000502:physiology; D008875:Middle Aged; D009483:Neuropsychological Tests; D010775:Photic Stimulation; D012720:Severity of Illness Index; D013702:Temporal Lobe / Q000473:pathology*; D055815:Young Adult
keywords: Hippocampus; Lesion; Medial temporal lobe; Visuo-spatial memory