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Age-related differences in the neural bases of landmark versus geometric spatial cue processing
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Edité par CCSD -
International audience. Orienting oneself in the environment requires the processing of visual spatial cues. The neural network implicated in the processing of spatial information is affected by ageing, which leads to prominent navigational impairments. Research is hinting at age-related changes in the use of geometric cues (e.g., the shape of the environment) and landmarks (e.g., discrete objects in the environment). However, the neural correlates of such age-related differences in visual cue reliance remain elusive. To address this issue, the present functional magnetic resonance imaging (fMRI) study aimed at investigating the brain activity associated with landmark-and geometrybased navigation. Twenty-five young adults and twenty-two older adults performed a virtual navigation task in the scanner. Participants explored a Y-maze and had to learn the location of a hidden goal. Subjects were then asked to navigate to the goal from different starting positions throughout the maze in two separate conditions: a landmark condition, in which reorientation required the processing of three differently-shaped objects; and a geometry condition, in which reorientation required the processing of the environment's shape. Young adults performed similarly in both conditions. However, at the cortical level, two distinct cerebral networks were found to mediate landmark-and geometry-based reorientation. Reorienting based on landmark information was associated with a greater occipital, hippocampal, and cerebellum involvement, as well as a specific activation of the perirhinal cortex. In contrast, reliance on the geometric shape of the environment elicited activity in the anterior cingulate and frontal cortices. In the older adult group, our preliminary analyses suggest specific deficits in the landmark condition associated with a decreased neural activity in the perirhinal cortex. Understanding age-related changes in visual spatial cue processing is essential to the design of appropriate spatial layouts that could enhance older adults' autonomy.
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