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MAMONE, BERNADETT, M.ED. AUGUST 2013 BIOMEDICAL SCIENCESMOTOR IMAGERY TRAINING FACILITATES NEURAL ADAPTATIONS ASSOCIATED WITH MUSCLE STRENGTHENING IN AGING (208 PP.)Director of Thesis: Guang, H. YueBackground. Aging is accompanied by a decline in muscle strength. However, the underlying mechanism is not fully understood. Growing evidence indicates that voluntary muscle strength training paradigms enhance descending cortical drive and strengthen muscle output in the elderly. Motor Imagery Training (MIT) may improve strength, however, it is not known if MIT can reverses aging-related maladaptive changes and how the underpinnings differ from those of conventional strength training (CST). Using Transcranial Magnetic Stimulation (TMS) and Electroencephalography (EEG), we studied the relation between training-related motor cortical changes and muscle strengthening in the elderly. Methods. Thirty-two right-handed, healthy older adults (74.41±7.09 yrs) were randomly assigned to either an 8-week MIT (n=15) or CST (n=10) group for left elbow flexion (EF) strengthening. A non-training elderly control (n=7) and twenty non-training young (23±4.02 yrs) subjects were also included. We measured maximal left arm EF and elbow extension (EE) force before and after training using a computerized force transducer and electromyography (EMG) to detect changes in relative antagonist muscle EMG and co-contraction. TMS was used to test the excitability of corticospinal pathways, intra-cortical and inter-hemispheric connections. Central motor drive was assessed using EEG. Results. Before training, there were significant age-related effects. Elderly had significantly (p=0.044) lower strength, antagonist muscle EMG (p=0.001), inter-hemispheric inhibition (IHI; p=0.032), stronger brain activation in beta (13-30 Hz; p |
