Abstract
Healthy ageing is characterised by deterioration of motor performance. In normal circumstances motor adaptation corrects for movements’ inaccuracies and as such, it is critical in maintaining optimal motor control. However, motor adaptation performance is also known to decline with age. Anodal transcranial direct current stimulation (TDCS) of the cerebellum and the primary motor cortex (M1) have been found to improve visuomotor adaptation in healthy young and older adults. However, no study has directly compared the effect of TDCS on motor adaptation between the two age populations. The aim of our study was to investigate whether the application of anodal TDCS over the lateral cerebellum and M1 affected motor adaptation in young and older adults similarly. Young and older participants performed a visuomotor rotation task and concurrently received TDCS over the left M1, the right cerebellum or received sham stimulation. Our results replicated the finding that older adults are impaired compared to the young adults in visuomotor adaptation. At the end of the adaptation session, older adults displayed a larger error (−17 deg) than the young adults (−10 deg). The stimulation of the lateral cerebellum did not change the adaptation in both age groups. In contrast, anodal TDCS over M1 improved initial adaptation in both age groups by around 30% compared to sham and this improvement lasted up to 40 min after the end of the stimulation. These results demonstrate that TDCS of M1 can enhance visuomotor adaptation, via mechanisms that remain available in the ageing population.
Highlights
When tested with sensitive laboratory-based behavioural tests, healthy ageing has been shown to be associated with a general reduction in motor performance, characterised by decreases in accuracy, coordination and movement speed and increases in movement duration and variability (Seidler et al 2002, 2010; Krampe, 2002; Sarlegna, 2006; Heuninckx et al 2008; Dutta et al 2013)
These contrasts were far from being significant (Bonferroni post hoc tests for older primary motor cortex (M1) vs. older sham: P = 0.26; for older M1 vs. older cerebellum: P = 0.23; for young cerebellum vs. young sham: P = 0.11; for young M1 vs. young sham: P = 1). This result suggests that transcranial direct current stimulation (TDCS) over M1 or the cerebellum did not modify the initial motor performance in this joystick task
The main finding of this study is that anodal TDCS over M1 improved the acquisition of motor adaptation in both young and older adults
Summary
When tested with sensitive laboratory-based behavioural tests, healthy ageing has been shown to be associated with a general reduction in motor performance, characterised by decreases in accuracy, coordination and movement speed and increases in movement duration and variability (Seidler et al 2002, 2010; Krampe, 2002; Sarlegna, 2006; Heuninckx et al 2008; Dutta et al 2013) These impairments are linked to change in brain structure such as regional cortical thinning, decreases in the volume of subcortical structures, concordant ventricular enlargement and changes in white matter integrity (Salat et al 2004; Walhovd et al 2005, 2011; Fjell et al 2009; Hafkemeijer et al 2014; Sexton et al 2014). Several studies have reported that motor adaptation is impaired in older adults and as such may play a role in the general decline of motor performance in the ageing population (Buch et al 2003; Bock & Girgenrath, 2006; Seidler, 2006; Anguera et al 2010; Heuer & Hegele, 2011; Langan & Seidler, 2011; Huang & Ahmed, 2014)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
