Effects of age on sleep and consolidation of motor learning

Thesis

Background: Our ability to consolidate what we learn changes with age. However, little is known about the neurophysiological underpinnings of consolidation of motor learning in ageing. This is largely because studies have repeatedly demonstrated a deficit in sleep-dependent consolidation of motor learning in older adults. This thesis aims to reassess commonly held assumptions about consolidation in ageing, as well as to examine the neurophysiological and neurochemical mechanisms that support the learning and consolidation processes.

Methods: Most of the studies in this thesis are based on the design of a novel whole-hand task for use in older adults, which reduces dependency on fine motor skill. This thesis adopts a number of converging measures to examine learning and memory including electroencephalograhy (EEG), magnetic resonance spectroscopy (MRS), actigraphy recordings, as well as behavioural and self-reported measures of sleep.

Results: Findings show significant improvements in learning with the adapted motor task in older adults. Importantly, this task reveals significant sleep- dependent enhancements in older adults, which are comparable to those seen in younger controls. Functional changes in sleep architecture with ageing show overall decline in slow wave sleep. Sleep-dependent improvements were specifically associated with activity in stage 3 slow wave sleep and increased hemispheric differences regardless of age. Changes in GABA concentrations with learning on a visuomotor tracking task showed marked variability across participants, and no clear associations were found between GABA and consolidation.

Conclusion: The evidence presented in this thesis highlight the complex dynamics underlying sleep consolidation, and challenges a commonly held assumption about consolidation in older adults. Specifically, the studies presented here show that observed declines in motor consolidation with ageing may be contaminated by age-related deficits fine motor skill. By removing such kinematic constraints, it was possible to detect marked improvements in motor performance also in older adults despite age-related changes in sleep architecture.

Authors: Gudberg, C

• Publication date: 2013
• DOI: 10.5287/ora-noxnvynpr
• Type of award: DPhil
• Level of award: Doctoral
• Awarding institution: Oxford University, UK
• Language: English
• Keywords: sleep; consolidation; learning; ageing; memory
• Subjects: Neuroscience; Medical Sciences