Solveig Vieluf

• Age-related differences in fine motor control are characterized by general slowing and higher variability. Little is known about the early stages of the deterioration of fine motor control. The main research question of my dissertation was how age and expertise influence fine motor control during the middle-aged lifespan with particular attention to possible effects of task characteristics, i.e. uni- or bimanual tasks, required various target profiles, speeds, and force levels. Three series of experiments have been conducted using uni- and bimanual tasks in different age groups (young, early middle-aged, and late middle-aged adults) and practice levels (novices and experts) collecting kinetic (force control and coordination) and neurophysiological (EEG) data. Performance deteriorated with increasing age. Age-related differences were higher in bi- than in unimanual tasks and in tasks requiring comparably high force production per time. Reduced attention allocation with increasing age was a decisive factor - deficits occurred during innervating both hands at the same time, integrating different coordination patterns of both hands, and integrating visual feedback. Additionally, middle-aged compared to younger adults initiated corrective movements more slowly. Experts outperformed novices in all tasks. This indicates positive plasticity. Fine motor control of experts was more efficient on a behavioral as well as a neurophysiological level. Age affects fine motor control already in middle-aged adults. The amount of remarkable age-related loss depends on task characteristics. Extensive and dexterous use of hands leads to maintenance or even improvement of fine motor control. Our results contribute to a better understanding of the underlying mechanisms of age- and expertise-related differences in fine motor control and they provide useful starting points to future research on bimanual coordination, learning, and neurophysiological correlates over the lifespan.