Abstract
Aging is typically associated with substantial declines in motor functioning as well as robust changes in the functional organization of brain networks. Previous research has investigated the link between these 2 age-varying factors but examinations were predominantly limited to the functional organization within motor-related brain networks. Little is known about the relationship between age-related behavioral impairments and changes in functional organization at the whole brain (i.e., multiple network) level. This knowledge gap is surprising given that the decreased segregation of brain networks (i.e., increased internetwork connectivity) can be considered a hallmark of the aging process. Accordingly, we investigated the association between declines in motor performance across the adult lifespan (20-75 years) and age-related modulations of functional connectivity within and between resting state networks. Results indicated that stronger internetwork resting state connectivity observed as a function of age was significantly related to worse motor performance. Moreover, performance had a significantly stronger association with the strength of internetwork as compared with intranetwork connectivity, including connectivity within motor networks. These findings suggest that age-related declines in motor performance may be attributed to a breakdown in the functional organization of large-scale brain networks rather than simply age-related connectivity changes within motor-related networks.
Highlights
A substantial impediment to healthy living in older adults is the compromised functioning of the motor system
Results indicated that stronger internetwork resting state connectivity observed as a function of age was significantly related to worse motor performance
These findings are consistent with numerous earlier studies indicating agerelated degradations in motor functioning, including on bimanual coordination task (BCT) similar to that employed in the current study (Heuninckx et al 2008; Solesio-Jofre et al 2014; Serbruyns et al 2015)
Summary
A substantial impediment to healthy living in older adults is the compromised functioning of the motor system (for reviews, see Seidler et al 2010; King et al 2013; Maes et al 2017). It is well established that brain activity at rest in young adults is organized into predominantly segregated functional networks; regions within these different networks demonstrate spontaneous yet correlated fluctuations in activity that are interpreted to be functionally connected (Biswal et al 1995; Fox et al 2005; Damoiseaux et al 2006; Fox and Raichle 2007; van den Heuvel and Hulshoff Pol 2010) These networks are known to change substantially with age, with a decrease in connectivity within the default mode network being the most commonly reported finding (Andrews-Hanna et al 2007; Damoiseaux et al 2008; Tomasi and Volkow 2012; Ferreira and Busatto 2013; Geerligs et al 2015; Ferreira et al 2016). Investigations into age-related changes within motor resting state networks have revealed both increased and decreased connectivity, heterogeneous results that appear to be at least partially attributed to the specific brain regions included as part of the networks of interest (Wu, Zang, Wang, Long, Hallett, et al 2007; Wu, Zang, Wang, Long, Li, et al 2007; Tomasi and Volkow 2012; Bo et al 2014; Solesio-Jofre et al 2014; Song et al 2014; Geerligs et al 2015; Seidler et al 2015)
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