Electronic Thesis and Dissertation Repository

Degree

Master of Science

Program

Psychology

Supervisor

Dr.Adrian Owen

Abstract

Periodic Limb Movement Disorder (PLMD) is a neurodegenerative disease characterized by dysfunction of the striatum and brief, repetitive limb movements during sleep. PLMD can severely disrupt non-rapid eye movement (NREM) sleep. Motor skills learning and memory consolidation are dependent on striatal activation, the latter enhanced by NREM sleep. Therefore, we investigated whether individuals with PLMD had learning and sleep-related memory deficits, and whether this putative deficit was related to sleep quality or symptom severity. 14 adults with a PLM index >15/hr underwent two nights (baseline, training) of polysomnographic recording. 15 age-matched healthy controls underwent three nights (baseline, undisturbed training and disturbed training) of polysomnographic recording. On the training nights, participants learned an explicit motor sequence learning (MSL) task and paired associates (PA) task at 8PM and were retested the following morning at 8AM. The healthy controls were then trained on a new sequence and a new word list and were retested at 8PM. Sleep quality was significantly worse at baseline in the PLMD group compared to controls (e.g. sleep efficiency, awakenings, etc.). Training night sleep for the PLMD group was less fragmented and the quality did not differ from the undisturbed night of controls despite the presence of elevated PLMs. The PLMD group's MSL performance was significantly impaired compared to the control group during the training session, but the overnight performance gains between two conditions did not differ. The results suggest that despite sleep disturbances and striatal dysfunction, the PLMs group still yields overnight benefit to motor skill memory consolidation.

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