Different trajectories of decline for global form and global motion processing in ageing, Mild Cognitive Impairment and Alzheimer’s disease

Publication date: Available online 14 March 2017
Source:Neurobiology of Aging
Author(s): Gillian Porter, John Wattam-Bell, Antony Bayer, Judy Haworth, Oliver Braddick, Janette Atkinson, Andrea Tales
The visual processing of complex motion is impaired in Alzheimer's disease (AD). However, it is unclear whether these impairments are biased towards 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 (MCI) and healthy ageing, 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 MCI 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.



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