Different trajectories of decline for global form and global motion processing in aging, mild cognitive impairment and Alzheimer's disease

Abstract

The visual processing of complex motion is impaired in Alzheimer's disease (AD). However, it is unclear whether these impairments are biased toward the motion stream or part of a general disruption of global visual processing, given some reports of impaired static form processing in AD. Here, for the first time, we directly compared the relative preservation of motion and form systems in AD, mild cognitive impairment, and healthy aging, by measuring coherence thresholds for well-established global rotational motion and static form stimuli known to be of equivalent complexity. Our data confirm a marked motion-processing deficit specific to some AD patients, and greater than any form-processing deficit for this group. In parallel, we identified a more gradual decline in static form recognition, with thresholds raised in mild cognitive impairment patients and slightly further in the AD group compared with controls. We conclude that complex motion processing is more vulnerable to decline in dementia than complex form processing, perhaps owing to greater reliance on long-range neural connections heavily targeted by AD pathology.

Motion perception as a model for perceptual aging

“…Most studies indeed compared thresholds between just two age groups, i.e., between younger adults, typically aged between 18 and 30 years, and older adults, typically older than 60 years. Findings often show substantial age-related increase in coherence thresholds (Allen, Hutchinson, Ledgeway, & Gayle, 2010;Andersen & Atchley, 1995;Atchley & Andersen, 1998;Gilmore, Wenk, Naylor, & Stuve, 1992;Snowden & Kavanagh, 2006;Wojciechowski, Trick, & Steinman, 1995; but see also Porter et al, 2017). Moreover, speed discrimination (Genova & Bocheva, 2013;Norman, Ross, Hawkes, & Long, 2003) as well as motion direction discrimination (Ball & Sekuler, 1986;Bennett et al, 2007;Bocheva, Angelova, & Stefanova, 2013;Bogfjellmo et al, 2013) have been found to decline with increasing age.…”

“…The contribution of cognitive resources to these differences is still largely unexplored. Interestingly, there is some evidence from clinical studies that deficits scale across a continuum of age-related cognitive changes observed in healthy aging, mild cognitive impairment, and dementia (Porter et al, 2017). More research is needed in order to clarify to which extent cognitive resources can explain changes in motion perception during aging.…”

“…Although the notion of general age-related decline has also been considered for perceptual aging (e.g., Trick & Silverman, 1991), evidence from visual perception clearly supports highly specific age-related changes (for reviews see Andersen, 2012;Owsley, 2011). Similarly, age effects on motion perception have been found to be dissociated from other changes in visual perception (e.g., Porter et al, 2017;Shaqiri et al, 2015), and even within the domain of motion perception differential effects have been observed (e.g., Billino, Bremmer, & Gegenfurtner, 2008;. Most importantly, motion perception has been shown to be highly sensitive to gradual age-related changes across adulthood (Billino et al, 2008;Bogfjellmo, Bex, & Falkenberg, 2013;Tran, Silverman, Zimmerman, & Feldon, 1998;Trick & Silverman, 1991).…”

A Computerized Continuous-Recognition Task for Measurement of Episodic Memory

“…[70]. Several assessment approaches have been examined as screening tests for MCI; most focusing on memory testing [11,[71][72][73][74], as well as for making a diagnosis of MCI [7,23,[75][76][77]. However, the MCI diagnosis is crude and not well implemented clinically.…”

“…With progressively increasing attention to MCI, more precise assessment technologies are being developed for when an individual lies on the temporal trajectory from normal to dementia [55,76,78,79], and such improved approaches are being suggested for measuring the progressive decline of cognitive function associated with early AD as well as assessing the benefits of intervention trials [13-15, 75, 80].…”