Year: 2019
Type: dissertation
Abstract: This thesis investigated whether the strength of primary motor cortex (M1) short-interval Intracortical inhibition (SICI) can predict an individual’s ability to stop prepotent actions. Experiments involved measuring SICI at rest (i.e. during relaxed muscle activity) or during a stop signal task. Chapter 3 showed that stronger resting-state SICI predicted more efficient stopping. Chapter 4 showed that more efficient stopping was associated with stronger SICI during action stopping. Chapter 5 showed that SICI in left and right M1 uniquely predicted stopping ability of the contralateral hand but not the ipsilateral hand, suggesting there is a hemisphere-specific influence of SICI over stopping ability. This was further supported by Chapter 6, which showed that left M1 SICI was stronger when the contralateral (right) hand vs. ipsilateral (left) hand was selected to stop. Chapter 6 also showed that subjects trained in the stop signal task either within one session and across multiple sessions, displayed increases in resting-state SICI strength and increased SICI strength during action stopping. These findings demonstrate a strong link between stopping ability and SICI measured outside of and during task context, with a stronger influence of SICI over the stopping ability in contralateral actions. This thesis also had an applied question, which was to investigate whether SICI is altered in gamblers, a population associated with impaired stopping ability. Chapter 2 consisted of a meta-analysis which showed that gambling disorder is associated with impairments in action stopping. Chapter 3 showed that those classified as problem gamblers exhibited reduced SICI and increased glutamate-mediated Intracortical facilitation relative to controls. This suggests intracortical circuits within M1 altered in problem gamblers, which may be functionally implicated in the inability to stop gambling urges. This thesis makes contributions to our understanding of the mechanisms of action stopping, and the aetiology of gambling problems.
Author: Nahian S. Chowdhury
Language: English
Subfield: Neurology
Field: Neuroscience
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W3011734266