Differential brain activity in visuo-perceptual regions during landmark-based navigation in young and healthy older adults

Abstract

14Older adults exhibit prominent impairments in their capacity to navigate, reorient in 15 unfamiliar environments or update their path when faced with obstacles. This decline in 16 navigational capabilities has traditionally been ascribed to memory impairments and 17 dysexecutive function whereas the impact of visual aging has often been overlooked. The 18 ability to perceive visuo-spatial information such as salient landmarks is essential to navigate 19 in space efficiently. To date, the functional and neurobiological factors underpinning 20 landmark processing in aging remain insufficiently characterized. To address this issue, this 21 study used functional magnetic resonance imaging (fMRI) to investigate the brain activity 22 associated with landmark-based navigation in young and healthy older participants. Twenty-23 five young adults (µ=25.4 years, σ=4.7; 7F) and twenty-one older adults (µ=73.0 years, 24 σ=3.9; 10F) performed a virtual navigation task in the scanner in which they could only orient 25 using salient landmarks. The underlying whole-brain patterns of activity as well as the 26 functional roles of scene-selective regions, the parahippocampal place area (PPA), the 27 occipital place area (OPA), and the retrosplenial cortex (RSC) were analyzed. We found that 28 older adults' navigational abilities were diminished compared to young adults' and that the 29 two age groups relied on distinct navigational strategies to solve the task. Better performance 30 during landmark-based navigation was found to be associated with increased neural activity in 31 an extended neural network comprising several cortical and cerebellar regions. Direct 32 comparisons between age groups further revealed that young participants had enhanced 33 anterior temporal activity. In addition, young adults only were found to recruit occipital areas 34 corresponding to the cortical projection of the central visual field during landmark-based 35 navigation. The region-of-interest analysis revealed increased OPA activation in older adult 36 participants. There were no significant between-group differences in PPA and RSC 37 activations. These results hint at the possibility that aging diminishes fine-grained information 38 processing in occipital and temporal regions thus hindering the capacity to use landmarks 39 adequately for navigation. This work helps towards a better comprehension of the neural 40 dynamics subtending landmark-based navigation and it provides new insights on the impact 41 of age-related visuo-spatial processing changes on navigation capabilities. 42 65 place-based strategy involves the formation of mental map-like representations of the absolute 66 spatial position of the goal in relation to various stimuli within the environment. A response-67 based strategy refers to the process whereby an association between a specific stimulus and 68 the goal location is formed. The choice of a navigation strategy critically depends on the 69 visual information present in the environment (Foo et al., 2005; Ratli...

Differential Brain Activity in Regions Linked to Visuospatial Processing During Landmark-Based Navigation in Young and Healthy Older Adults

“…We thank Konogan Baranton and Isabelle Poulain (Essilor International) for the manufacturing of MRI-compatible glasses. A preliminary version of this manuscript has been released as a pre-print on bioRxiv (Ramanoël et al, 2020 ).…”

Selective neural coding of object, feature, and geometry spatial cues in humans

“…These results have important implications. Extensive literature points to prominent navigational impairments in healthy aging associated with changes in a vast neural network [88][89][90][91]. We revealed that while objects and features can be used equally well to orient in space, object-based navigation is subtended by a more widespread pattern of temporal and occipital activations.…”

“…Spatial frequency content, contrast amplitude, angular size, and position in the visual field may constitute interesting research avenues. Recent studies have revealed that age-related impairments in navigational abilities could be partially explained by the decline of information processing in early visual regions [91,114]. Therefore, specific modulations of these basic visual properties could stabilize or even improve navigation performance ultimately facilitating mobility in normal and pathological aging.…”

“…Notably, the object and control conditions were also analyzed and included as control data in a study on healthy aging [91].…”