Abstract
We provide direct electrophysiological
evidence that mirror therapy (MT) can change brain activity
and aid in the recovery of motor function after stroke. In this
longitudinal single-case study, the subject was a 58-yr-old man with
right-hand hemiplegia due to ischemic stroke. Over a 9-mo period we
treated him with MT twice a week and measured electroencephalograms
(EEG) before, during, and after each therapy session. Using
advanced signal processing methods, we identified five distinct movement-
related oscillatory EEG components: one slow component designated
as mu rhythm and four faster components designated as
sensorimotor rhythms. Results show that MT produced long-term
changes of two oscillatory EEG components including the mu rhythm,
which is a well-documented correlate of voluntary movement in the
frequency range of 7.5-12 Hz. Specifically, MT was significantly
associated with an increase in the power of mu rhythm recorded over
both hemispheres and a decrease in the power of one sensorimotor
component recorded over the affected hemisphere. To obtain robust,
repeatable individual measures of EEG components suitable for longitudinal
study, we used irregular-resampling autospectral analysis to
separate fractal and oscillatory components in the EEG power spectrum
and three-way parallel factor analysis to isolate oscillatory EEG
components and track their activations over time. The rhythms were
identified over individual days of MT training and were clearly related
to the periods of event-related desynchronization and synchronization
(rest, observe, and move) during MT. Our results are consistent with
a model in which MT promotes recovery of motor function by altering
neural activity associated with voluntary movement.
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