Abstract
Ageing is associated with pronounced changes in oculomotor control. However, there is still a lack of understanding of selective vulnerabilities. Dopaminergic modulation provides a key candidate neuronal correlate that might shape age-related functional differences. We investigated the link between individual differences in dopaminergic activity and age effects on oculomotor control. A large sample of 119 adults ranging in age from 20 to 80 years was genotyped for two well-documented polymorphisms, the COMT Val158Met polymorphism and the SLC6A3 3′-UTR-VNTR polymorphism, that are functional for dopamine signalling. We characterized oculomotor control using a battery of different eye movement tasks including saccade as well as smooth pursuit paradigms. Tasks involved varying cognitive demands, e.g. attentional control, working memory and anticipatory processes. We analysed age effects on oculomotor parameters and determined links to individual differences in the dopaminergic system. Our results corroborate the well-documented deterioration of processing speed with age, but at the same time suggest remarkably robust oculomotor capacities. However, performance patterns across the different eye movement tasks indicate that selective vulnerabilities of oculomotor control emerge from involved cognitive processes that are prone to decline and can interfere with efficient visual information use. Furthermore, we found that these specific functional age differences are magnified by dopaminergic polymorphisms. We conclude that age-related differences in oculomotor control are closely linked to cognitive control that is subject to dopaminergic modulation. Individual differences in dopamine neurotransmitter functioning provide a putative mechanism of oculomotor resilience in ageing.