Electronic Thesis and Dissertation Repository

Thesis Format

Integrated Article

Degree

Doctor of Philosophy

Program

Neuroscience

Supervisor

Gribble, Paul L.

2nd Supervisor

Diedrichsen, Jörn

Co-Supervisor

Abstract

From typing to playing the piano, sequences of finger movements are essential in our everyday lives. To become skilled at any task, takes practice and determination. To remember and perform a sequence of movements, we form an abstract mental representation of it. To estimate our performance accuracy, we usually rely on sensory feedback from our environment. For instance, when playing piano, we pay close attention to the tone that is played. To improve performance, we adjust our mental representation by integrating this sensory feedback. The goal of this thesis was to elucidate how the mental representation and feedback control of finger movement sequences change with training. We first examined whether the mental representation of a movement sequence can be shaped early in training and how this modulation impacts performance long-term. To this end, we used a discrete sequence production task, in which participants performed sequences of finger presses on a keyboard-like device. We influenced participants’ initial representation to be either beneficial or detrimental to performance and estimated how these instructions impacted subsequent performance. Participants’ performance was continuously influenced by the instructions throughout a three-week training period. Only if participants abandoned the detrimental instruction could they improve their performance. Next, we investigated how feedback control changes across training. Using the same task, we probed feedback integration over four days by either delaying or advancing the time at which participants received the sensory feedback from the keypress. We found that the feedback perturbations consistently slowed or advanced participants’ performance on the perturbed press in accordance with the direction of the perturbation. Nevertheless, the amount of behavioural adjustment decreased with training, suggesting a reduction in feedback integration. In both studies, we could show that the mental representation of skilled movement sequences was hierarchically organized. In summary, this thesis provides novel insights into the change in representation and control of finger movement sequences with training.

Summary for Lay Audience

Sequences of movements are essential in our everyday life, from tying shoelaces to playing tennis. By combining simpler movements into longer actions, we can perform movements with sublime artistry such as playing a Beethoven symphony on the piano. To be able to learn and modify such sequences of movements, we need to hold and modify them in our mind. To do so, we represent them as an abstract organization in our brain, which is also termed a mental representation. One key question is how does practice change the mental representation of a movement sequence. One factor that might influence learning is the instructions we receive – through teachers, parents, or other types of media (e.g., YouTube). Such instructions are commonly thought to advance learning. Nevertheless, in some cases, instructions can hinder learning. In the first part of this thesis, we investigated whether providing beneficial or detrimental instructions during the early phase of learning can shape the mental representation and performance of a movement sequence long-term. We found that over a three-week training period, the instructions continuously impacted participants' mental representation and performance. Only if participants were able to abandon the detrimental instructions could they improve their performance. The second part of this thesis investigated how we use sensory feedback during movement execution. For example, when playing the piano, we pay close attention to the produced tone. If we hear a wrong tone, we adjust which key is pressed. This illustrates the importance of sensory feedback during movement sequence execution. While we rely heavily on sensory feedback early in training, it has been suggested that we use it less with practice. To test this, we modified the sensory feedback participants received upon a keypress by delaying or advancing it by a small amount of time. We found that while sensory feedback was indeed less used as learning progressed, the perturbation still significantly influenced participants’ performance, by slowing or speeding up their movement execution in accordance with the perturbation direction. Together, this thesis investigated how instructions shape the mental representation of sequences and how feedback is integrated during movement execution.

Download

Share

COinS