Effects of Altered Sensory Input from the Neck on Cerebellar Function, Body Schema and Sensorimotor Integration by Julianne Baarbé Submitted in Partial Fulfillment of the Requirements for the Degree Masters of Health Sciences at University of Ontario Institute of Technology, June 2015 Effects of Altered Sensory Input from the Neck on Cerebellar Function, Body Schema and Sensorimotor Integration by Julianne Baarbé Abstract Neck muscles have a high density of muscle spindle afferents and their input is critical for formulating the perception of head position relative to the body. Chronic alterations in afferent input from the neck may be studied in individuals with subclinical neck pain (SCNP), defined as non-severe recurrent neck pain lasting at least three months in the past year and testable on pain-free days so as to explore altered-afferent-input effects on cerebellar processing, upper extremity function and spatial awareness in the absence of pain. The first study tested participants with SCNP using transcranial magnetic stimulation to activate the cerebellar-thalamic-cortical circuit and produce cerebellar inhibition (CBI). SCNP participants were randomized to receive cervical manipulation or passive head movement (PHM), following which all participants completed a motor acquisition task. Healthy controls and SCNP participants who received manipulation showed significantly less CBI and improved motor performance whereas the SCNP group who received PHM showed no changes to CBI. The second study tested SCNP participants on upper extremity dart throwing. Three sets of ten darts were thrown at a slow-to-normal speed and three sets of ten darts were thrown at a fast speed. Compared to healthy participants, SCNP participants showed significantly greater elbow and forearm variability in motor selection, greater peak acceleration velocity of shoulder flexion-extension movement, and greater peak deceleration velocity of wrist movement. The third study looked at whether SCNP also impacted spatial awareness beyond an egocentric frame of reference, by measuring the response time to recognize objects which were rotated relative to their usual orientation. The SCNP group showed slower mental rotation at baseline and a smaller improvement when measured after four weeks (8.6%) in comparison to the healthy group (16.1%). These studies provide compelling evidence that chronic alterations in sensory input from the neck influences cerebellar integration leading to changes to upper extremity movement and spatial awareness of object orientation. Keywords: altered sensory input, subclinical neck pain (SCNP), sensorimotor integration, cerebellum, body schema Thesis supervisor: Professor Bernadette Murphy Title: Head of Kinesiology, Professor, Faculty of Health Sciences University of Ontario Institute of Technology ii Statement of Originality I hereby declare that this thesis is, to the best of my knowledge, original, except as acknowledged in the text, and that the material has not been previously submitted either in whole or in part, for a degree at this or any other University. iii Acknowledgements I would like to take this opportunity to express my gratitude to my supervisor Professor Bernadette Murphy who has always supported my endeavours. You have opened up a world of scientific discovery to me, and I am grateful for this. Thank you to Dr. Paul Yielder. Your knowledge of human neuroanatomy has formed the basis for much of my work. To Dr. Michael Holmes, thank you for helping me learn challenging biomechanics techniques and guiding this part of my thesis. To Dr. Heidi Haavik, Director of Research at New Zealand College of Chiropractic. Your work has sparked many discoveries, and I am grateful for all your contributions. To Julian Daligadu, previous student in the Human Neurophysiology and Rehabilitation Laboratory, thank you for helping me learn while I was still an undergraduate student. I truly believe your presence in the lab brought me to where I am today. To my colleagues Chad Larabie, Ryan Gilley, Joseph Guirguis, and Devon Jarrett. Your motivation has inspired me, and your dedication to help in any way possible including running experiments and analyzing of data has been instrumental. To all the students, colleagues and friends who participated in countless experiments. Thank you for coming to the school to participate even when you had exams, assignments, work, and other responsibilities. My thesis would not be possible without your dedicated support. Special gratitude to University of Ontario Institute of Technology for being nearby when I needed a place to go to. Thank you to Ontario Graduate Scholarships and Canadian Institutes of Health Research for gracious funding support that helped to bring me to where I am today. To the Australian Spinal Research Foundation, thank you for generously providing equipment which has aptly facilitated outcomes of my thesis. To the Natural Sciences and Engineering Research Council of Canada, thank you for generously supporting our research lab. To the Canadian Memorial Chiropractic College, thank you for generously providing software that I used to complete a large portion of data analysis for my thesis. I also have tremendous gratitude to my mom, my dad, my nana, my papa, my oma, and my opa who have always been there when I needed them. To my siblings Jeremy, Jasper, Josiah, Justin, Jennessa, Jannelle, Joel, Jethro and Joylynn, thanks for your kind gestures and for just being there. It always cheers me up to have one of you close by. Last, but not least, to my biggest supporter Hojjat, who is a talented researcher and friend. I hope we have a bright future together! iv v Table of Contents Chapter 1: Introduction ................................................................................................... 1 1.1 Introduction .......................................................................................................... 1 1.2 Altered Afferent Input .......................................................................................... 2 1.3 Challenges to Motor Skill .................................................................................... 6 1.4 Challenges to Spatial Awareness ......................................................................... 9 1.5 Challenges to Mental Rotation ........................................................................... 12 1.6 Cerebellar Functioning ....................................................................................... 13 1.7 Muscle Activation Patterns ................................................................................ 14 1.7.1 Muscle activity in neck pain disorders ........................................................ 14 1.7.2 Muscle activity in cerebellar disorders ....................................................... 16 1.8 Effects of Altered Afferent Input on Multimodal Processing ............................ 17 1.8.1 The central nervous system’s response to adjust for sensory mismatches . 18 1.8.2 Sensory mismatches between two or more senses ...................................... 20 1.9 Summary and Relevance to Thesis .................................................................... 21 1.10 References....................................................................................................... 22 Chapter 2: Technical Considerations for Thesis ........................................................... 26 2.1 Introduction to Chapter ...................................................................................... 26 2.2 Introduction and Theoretical Background .......................................................... 26 2.3 Relevance and Significance to Thesis ................................................................ 27 2.4 Neurophysiological Signals ................................................................................ 28 2.4.1 Transcranial Magnetic Stimulation ............................................................. 28 2.4.2 Signal Application within Research ............................................................ 29 2.4.3 Physiological Considerations ...................................................................... 30 2.4.4 Proposed Features and Use of Signal for Thesis ........................................ 31 2.4.5 Quality Assurance ....................................................................................... 32 2.5 Kinematic Signals .............................................................................................. 33 2.5.1 Motion analysis ........................................................................................... 33 2.5.2 Signal Generation ........................................................................................ 34 2.5.3 Essential Characteristics ............................................................................. 35 2.5.4 Physiological Considerations ...................................................................... 36 2.5.5 Signal Application within Research ............................................................ 37 2.5.6 Proposed Features and Use of Signal for Thesis ........................................ 39 2.5.7 Quality Assurance ....................................................................................... 40 vi 2.6 References .......................................................................................................... 41 Chapter 3: Neck Pain Alters the Response of the Cerebellum Following Motor Training 44 3.1 Introduction to