Motor Skills Learning Plus Brain Stimulation for Stroke

Functional MRI was used to explore neural substrates.

A combination of motor skills learning and transcranial direct current stimulation may enhance recovery from a paralyzed limb for patients with stroke, according to a new study.

Motor skill learning is one of the key components of motor function recovery after stroke, it was noted. Transcranial direct current stimulation can enhance neurorehabilitation and motor skill learning in patients.

“Dual transcranial direct current stimulation applied during motor skill learning with a paretic upper limb resulted in prolonged shaping of brain activation,” stated the authors, led by Stéphanie Lefebvre of the Institute of Neuroscience in Brussels.

Pilot studies have shown that transcranial direct current stimulation, a noninvasive, painless cerebral stimulation method, modulates cerebral activity and increases the motor performances of patients with stroke. Low-voltage electric currents are applied to the patient’s head by means of electrodes for short periods.

The researchers used functional MRI (fMRI) to explore the neural substrates underlying differential patterns during motor skill learning.

The double-blind, cross-over randomized, sham-controlled study included 19 patients who had chronic hemiparetic stroke. The study consisted of 2 sessions. In an intervention session, dual transcranial direct current stimulation or sham was applied during motor skill learning with the paretic upper limb. In an imaging session 1 week later, the patients performed the learned motor skill. The motor skill learning task, called the “circuit game,” consisted of moving a pointer controlled by a computer mouse along a complex circuit as quickly and accurately as possible.

The patients with stroke learned the motor task with the paretic hand in the supine position to match their position in the MRI scanner 1 week later. The following week, they performed the learned motor task in the MRI scanner and their brain activity was recorded with fMRI.

“Compared to the sham series, dual transcranial direct current stimulation applied bilaterally over the primary motor cortex during motor skill learning with the paretic upper limb enhanced online motor skill learning,” the authors stated. The brain activation was more diffuse and less well organized 1 week after placebo stimulation, but it was much more focused 1 week after real stimulation, suggesting it was more efficient.

“The 1-week retention’s enhancement driven by the intervention was associated with a trend toward normalization of the brain activation pattern during performance of the learned motor skill relative to the sham series,” the researchers stated.

A similar trend toward normalization was observed during performance of a simple, untrained task without a speed/accuracy constraint, despite a lack of behavioral difference between the dual transcranial direct current stimulation and sham series.

The investigators noted that dual transcranial direct current stimulation applied during the first session enhanced continued learning with the paretic limb 1 week later, relative to the sham series. “This lasting behavioral enhancement was associated with more efficient recruitment of the motor skill learning network, that is, focused activation on the motor-premotor areas in the damaged hemisphere, especially on the dorsal premotor cortex,” they stated.

The researchers published their results online on December 9, 2014 in the journal Brain.