Abstract
Spatial navigation is a cognitive skill fundamental to successful interaction with our environment, and aging is associated with weaknesses in this skill. Identifying mechanisms underlying individual differences in navigation ability in aged adults is important to understanding these age-related weaknesses. One understudied factor involved in spatial navigation is self-motion perception. Important to self-motion perception is optic flow–the global pattern of visual motion experienced while moving through our environment. A set of optic flow-sensitive (OF-sensitive) cortical regions was defined in a group of young (n = 29) and aged (n = 22) adults. Brain activity was measured in this set of OF-sensitive regions and control regions using functional magnetic resonance imaging while participants performed visual path integration (VPI) and turn counting (TC) tasks. Aged adults had stronger activity in RMT+ during both tasks compared to young adults. Stronger activity in the OF-sensitive regions LMT+ and RpVIP during VPI, not TC, was associated with greater VPI accuracy in aged adults. The activity strength in these two OF-sensitive regions measured during VPI explained 42% of the variance in VPI task performance in aged adults. The results of this study provide novel support for global motion processing as a mechanism underlying visual path integration in normal aging.
Highlights
Accepted: 2 February 2021Spatial navigation is a complex, multisensory, cognitive skill critical to successful interaction with our environment, and aging is associated with weaknesses in this skill [1].Fundamentally, navigating space, or traveling from one place to another, requires understanding and updating our location within our environment as we move through it
As our goal was to test whether OF-sensitive cortical regions are involved in performance on spatial orienting tasks requiring the use of visual self-motion information, we used an optic flow localizer to identify the location of OF-sensitive regions that responded more strongly to coherent radial motion patterns than scrambled motion patterns at the group level in our sample
We focused on OF-sensitive regions because of their implication in visual self-motion perception; this is central to our visual path integration (VPI) task and is present in our turn counting (TC) task, but it is not essential to TC task performance
Summary
Accepted: 2 February 2021Spatial navigation is a complex, multisensory, cognitive skill critical to successful interaction with our environment, and aging is associated with weaknesses in this skill [1].Fundamentally, navigating space, or traveling from one place to another, requires understanding and updating our location within our environment as we move through it. A number of sensory and environmental cues, component processes, and types of spatial knowledge or spatial representations might be employed to navigate to a desired location; the specific cues, processes, and representations used depend on the context as well as the individual who is navigating [2,3,4]. One cue that has been relatively understudied in the context of understanding individual differences in environmental spatial abilities and the mechanisms underlying weakened spatial abilities in aged adults is optic flow. Optic flow is the coherent, radial motion pattern experienced when moving forward in a stable environment with one’s head and eyes facing forward [5] This characteristic global motion pattern provides information about the direction and speed of our self-motion as we move through our environment
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