M.Sc Thesis

M.Sc StudentKamara Gill
SubjectFinger Movement Generalization across Directions and Hands:
A Comparison between Musicians and Non-Musicians
DepartmentDepartment of Biomedical Engineering
Supervisor DR. Firas Mawase


Playing piano, or simply tying shoelaces, requires precise coordination of multiple fingers, some active in flexion direction, others in the extension and/or other directions, and some stay immobile. This extraordinary behavior is fundamental in human daily life and is particularly manifested by the way we generate and use specific patterns of muscles activity of multiple fingers when learning complex motor tasks and further when we generalize what has been learned in one context to other contexts. The coexistence of control signals of flexion and extension movements raises the question of whether the control processes of these actions interact and potentially generalize between each other, and across hands. We aim to determine whether generalization can be obtained across directions (i.e., flexion to extension) as well as across hands. Additionally, we will examine the effect of prior training history on the learning and generalization patterns. To do so, we recruited participants with intensive musical backgrounds (training >5 years). A total of 26 naive participants, randomly assigned to either a Flexor group (n=13) or an Extensor group (n=13), and Musicians (n=13) were recruited and underwent a week-long trial. On the first day, multiple dexterity measures were extracted from the force profiles of the ten digits, including finger Individuation Index (II), reaction time, and synchronization between active fingers. Following a 3-day training period which included performing single-finger and chord-like movements, the baseline assessments were performed again. Our data show that motor learning is generalized both across directions and across hands, but the extent of generalization can differ based on the type of motion that is trained. Additionally, musicians have improved generalization abilities compared to the general population. Our findings suggest interactive direction-dependent learning and generalization of multi-finger dexterous movements. Flexor direction seems to be more represented in the sensorimotor system than extensor direction. This ability, however, is modular as it depends on the history of prior training. Furthermore, our results have also potential clinical implications for motor rehabilitation in stroke survivors who often show profound disability in extensor finger movement.