The effect of old age on motor control: performance and learning

A decrease in motor ability can have a profound impact on a person’s capacity to maintain independence. Motor skill levels decline with age and this can create difficulties for older adults as they attempt to maintain independent lives. The fact that people in today’s society are living for much longer means that robust methods for examining movement in older adults, must be developed. These methods will increase our understanding of how movement deteriorates with age and inform approaches to rehabilitation in cases where movement is lost (e.g. motor paresis after stroke.

Accordingly, this doctoral research used sophisticated kinematic technology to create a series of computerised visuomotor tasks designed to achieve the following primary aims (i) to examine specific questions regarding age differences in motor performance; (ii) to create an experimental task to measure and infer potential causes of age-related changes in motor learning; and (iii) use the motor learning task to assess the outcomes of tDCS in healthy younger and older adults. A secondary aim was to produce tests that have the potential for use in rehabilitative settings, where more sensitive methods of assessment are required.

Chapter 1 reviews previous research on the topics of ageing, motor control, and rehabilitation, and identifies needs for further empirical investigation. Age differences in motor performance are examined in the experimental work of Chapters 2 and 3, which suggests that older people compensate for motor decline by making spatial and temporal adjustments to their movements in order to meet task demands – a finding that generalised between two different motor tasks. Chapter 4 considers performance differences between the preferred and non-preferred hand, and includes findings of a tracing study where manual asymmetries were reduced in older adults. The problems that can arise when measuring differences between the hands are, however, highlighted in the experimental work of Chapter 5. The research in Chapters 6 and 7 focuses on motor learning. In Chapter 6 a motor sequence learning task is developed, which was used to examine the relationship between motor performance and learning. This task paradigm was used again in Chapter 7, which begins by reviewing previous studies that have applied Transcranial Direct Current Stimulation (tDCS) to modify movement in healthy people and in stroke populations, and ends with two experiments that found no beneficial effects of tDCS on motor sequence learning in younger and older adults. Finally, Chapter 8 summarises the findings of each experimental chapter and considers future applications of the motor tasks designed throughout this doctoral work.