The effects of motor task complexity on sensorimotor integration: implications for healthy and subclinical populations

Abstract

The central nervous system’s (CNS) plastic ability allows for adaptation to the various physiological changes and experiences we encounter. This occurs through dynamic shifts within the connections and strengths of neural networks, altering the way in which the CNS integrates sensory information; a process termed sensorimotor integration (SMI). Plasticity is the mechanism for development and learning. However, it can also be a mechanism for maladaptive changes such as the organizational changes seen in people with overuse injuries and chronic pain. These maladaptive changes are associated with debilitating symptoms which include the deterioration of learning and retention of skills. The prevalence of repetitive strain and overuse injuries is steadily increasing given the rise of repetitive movement occupations and sedentary lifestyles. Typically, the neuroplastic changes associated with these disorders are identified with the use of neuroimaging techniques. While such techniques provide accurate imaging of the organizational changes that occur, they are expensive to provide, have long wait times and are generally only performed once symptoms have become debilitating. The investigation of repetitive movement and its effects on SMI can be combined with electrophysiological techniques such as somatosensory evoked potentials (SEPs) which directly measure the electrical activity of neural areas involved in learning. Understanding the processes of repetitive activity and the neuromodulatory changes which occur is fundamental in order to understand conditions which may lead to maladaptive changes that may initiate chronic pain and overuse disorders. The studies in this thesis aimed to first investigate the changes which occur following a motor learning task in neural networks of a healthy population, with attention to the cortico-subcortical and cortico-cerebellar projections which play crucial roles in motor learning and SMI. This information was then applied to a low grade neck pain population, providing insight into the early maladaptive changes which occur before the condition becomes severely chronic. The studies indicated that following a complex motor training task, significant changes in activity occurred within those cortico-subortical and cortico-cerebellar projections, known to be critical for effective learning and reiterating the importance of these areas in learning and SMI. When applied and compared to participants with current and/or recurrent neck pain, marked differences in neural areas associated with learning and SMI were seen, which was corroborated by inferior performance on the motor task. This study provides evidence that SEPs can be used as a screening tool and potential marker of the early stages of maladaptivity and the need for preventative measures.