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.

Differential Brain, Cognitive and Motor Profiles Associated with Partial Trisomy. Modeling Down Syndrome in Mice

“…It is difficult to identify the HSA21 genes with their triple copy being associated with ID because of the small number of segmental trisomies (Higurashi et al 1990 ;Poissonnier et al 1976 ). Another difficulty is the heterogeneity of the cognitive profile as some cognitive processes are strongly impacted while others are less impaired (Chapman and Hesketh 2001 ;Lavenex et al 2015 ;Patterson et al 2013 ;Vicari and Carlesimo 2006 ). This heterogeneity and the lack of validity of certain cognitive measures can explain discrepancies between studies (Delabar et al 1993 ;Korenberg et al 1994 ;Lyle et al 2009 ).…”

Using learning flexibly and remembering after a delay: understanding cognitive dysfunction in adults with Down syndrome

“…For instance, Courbois et al (2013) reported that, although individuals with DS could learn specific spatial routes in a virtual environment, albeit more slowly than MA-matched controls, they were unable to find a novel shortcut between two learned locations, suggesting difficulty with using spatial memory flexibly. Extending on this research using a real-world, spatial memory task, Banta Lavenex et al (2015) showed that individuals with DS learned and remembered associations between an object and its location similarly to MAmatched controls, but only when the location of the hidden object was cued by a colour. That is, memory was not impaired when participants could use a visual landmark to facilitate their memory for the hidden object.…”

“…(), this condition requires participants to form a flexible spatial representation of the area (Banta Lavenex et al . ). Both of these studies suggest that people with DS demonstrate particular impairments in linking individual details of an event into a flexible, relational framework.…”

“…Extending on this research using a real‐world, spatial memory task, Banta Lavenex et al . () showed that individuals with DS learned and remembered associations between an object and its location similarly to MA‐matched controls, but only when the location of the hidden object was cued by a colour. That is, memory was not impaired when participants could use a visual landmark to facilitate their memory for the hidden object.…”

“…In addition to encoding and retention, one aspect of episodic memory requiring further attention is how individuals with DS use learned information flexibly. Emerging findings on memory flexibility in people with DS come from work using spatial memory tasks (Courbois et al 2013;Banta Lavenex et al 2015;Farran et al 2015). For instance, Courbois et al (2013) reported that, although individuals with DS could learn specific spatial routes in a virtual environment, albeit more slowly than MA-matched controls, they were unable to find a novel shortcut between two learned locations, suggesting difficulty with using spatial memory flexibly.…”