A master thesis from Aalborg University
Changes in excitability of cortical projections to the tibialis anterior induced by concurrent motor imagination and peripheral electrical stimulation
Author(s)
Term
4. term
Publication year
2009
Submitted on
2009-06-04
Pages
41 pages
Abstract
Plasticity of the human motor cortex may play an important role in functional recovery after stroke. This study investigated a novel approach for changing excitability of the cortical projections to the tibialis anterior (TA), consisting of concurrent motor imagination and peripheral stimulation. It is hypothesized that changes in cortical excitability depend on when stimulation arrives during the cognitive process of movement. The movement-related cortical potential (MRCP) for each participating subject was measured. In three separate intervention sessions, repetitive pairings of an electrical stimulation applied to the common peroneal nerve was timed to arrive at the cortical level during an imaginary dorsiflexion in the preparation phase (INT1), in the execution phase (INT2) or after the execution phase (INT3) in relation to the individual MRCP. Motorevoked potentials (MEPs) were elicited in the TA before and after each intervention, and the TA MEP size was extracted. Across subjects, the largest increase in the MEP size was observed in INT1 (143%), while the increase was less in INT2 (118%) and further reduced in INT3 (107%). This supports the hypothesis that the arrival of the stimulation depends on the cognitive state, although the variability in the data was large. Changes in the TA MEPs appeared not to be caused by spinal mechanisms. In addition, no significant changes in the antagonist MEP size were observed. The present results indicate that the rationale behind the approach is sound, opening opportunities for new rehabilitation strategies. However, further research on additional subjects is required to validate the hypothesis.
Keywords
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