title: Allocentric spatial learning and memory deficits in Down syndrome.
abstract: Studies have shown that persons with Down syndrome (DS) exhibit relatively poor language capacities, and impaired verbal and visuoperceptual memory, whereas their visuospatial memory capacities appear comparatively spared. Individuals with DS recall better where an object was previously seen than what object was previously seen. However, most of the evidence concerning preserved visuospatial memory comes from tabletop or computerized experiments which are biased toward testing egocentric (viewpoint-dependent) spatial representations. Accordingly, allocentric (viewpoint-independent) spatial learning and memory capacities may not be necessary to perform these tasks. Thus, in order to more fully characterize the spatial capacities of individuals with DS, allocentric processes underlying real-world navigation must also be investigated. We tested 20 participants with DS and 16 mental age-matched, typically developing (TD) children in a real-world, allocentric spatial (AS) memory task. During local cue (LC) trials, participants had to locate three rewards marked by local color cues, among 12 locations distributed in a 4 m × 4 m arena. During AS trials, participants had to locate the same three rewards, in absence of LCs, based on their relations to distal environmental cues. All TD participants chose rewarded locations in LC and AS trials at above chance level. In contrast, although all but one of the participants with DS exhibited a preference for the rewarded locations in LC trials, only 50% of participants with DS chose the rewarded locations at above chance level in AS trials. As a group, participants with DS performed worse than TD children on all measures of task performance. These findings demonstrate that individuals with DS are impaired at using an AS representation to learn and remember discrete locations in a controlled environment, suggesting persistent and pervasive deficits in hippocampus-dependent memory in DS.
authors.affiliation: Laboratory for Experimental Research on Behavior, Institute of Psychology, University of Lausanne Lausanne, Switzerland.
authors.forename: Pamela Banta
authors.initials: PB
authors.lastname: Lavenex
authors.affiliation: Laboratory for Experimental Research on Behavior, Institute of Psychology, University of Lausanne Lausanne, Switzerland.
authors.forename: Mathilde
authors.initials: M
authors.lastname: Bostelmann
authors.affiliation: Laboratory for Experimental Research on Behavior, Institute of Psychology, University of Lausanne Lausanne, Switzerland.
authors.forename: Catherine
authors.initials: C
authors.lastname: Brandner
authors.affiliation: Department of Neuroscience, Bambino Gesù Children's Hospital Rome, Italy.
authors.forename: Floriana
authors.initials: F
authors.lastname: Costanzo
authors.affiliation: Laboratory for Experimental Research on Behavior, Institute of Psychology, University of Lausanne Lausanne, Switzerland.
authors.forename: Emilie
authors.initials: E
authors.lastname: Fragnière
authors.affiliation: Laboratory for Experimental Research on Behavior, Institute of Psychology, University of Lausanne Lausanne, Switzerland.
authors.forename: Giuliana
authors.initials: G
authors.lastname: Klencklen
authors.affiliation: Laboratory for Experimental Research on Behavior, Institute of Psychology, University of Lausanne Lausanne, Switzerland.
authors.forename: Pierre
authors.initials: P
authors.lastname: Lavenex
authors.affiliation: Department of Neuroscience, Bambino Gesù Children's Hospital Rome, Italy.
authors.forename: Deny
authors.initials: D
authors.lastname: Menghini
authors.affiliation: Department of Neuroscience, Bambino Gesù Children's Hospital Rome, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Vicari
keywords: capacity; episodic; genetic disorder; hippocampus; memory; resolution