The ability to learn and retain new motor skills is pivotal for everyday life activities and motor rehabilitation after stroke. However, people show considerable individual differences in motor learning. Understanding the neurophysiological processes underlying these individual differences is of significant scientific and clinical importance. At a mechanistic level, oscillations in the beta frequency range (15–30 Hz), fundamental for motor control, reflect underlying cortical inhibitory and excitatory mechanisms. As such, they may provide appropriate biomarkers with which to bridge the gap between cellular and behavioural accounts of cortical plasticity in both healthy and diseased states. This thesis explores the interplay between cortical beta oscillations and individual differences in short-term motor learning within the context of healthy ageing and after stroke. First, I assess the test-retest reliability of resting and movement-related beta estimates in a group of healthy subjects across several weeks. By demonstrating that EEG-derived power measures of beta activity are highly reliable, I validate the notion that these measures reflect meaningful individual differences that can be utilized in basic research and in the clinic. Second, I probe the neurophysiological mechanisms underlying natural inter-individual differences in short-term motor learning. I demonstrate comparable motor learning ability between young and elderly individuals, despite age-related alterations in beta activity. Implementing a multivariate approach, I show that beta dynamics explain some of the individual differences in post-training tracking performance. Third, I extend this line of research by focusing on stroke-related inter-individual variations in motor learning. Employing the same tasks and analyses, I demonstrate preserved, albeit reduced motor learning ability and no aberrant beta activity after stroke. Beta dynamics explained some of the individual differences in stroke patients’ performance 24 hours after training, and may thus offer novel targets for therapeutic interventions
