Researchers look at cerebellum stimulation to aid walking

According to a statement, the findings suggest that cerebellar transcranial direct current stimulation (tDCS) may be a valuable therapy tool to aid people relearning how to walk following a stroke or other brain injury.

Previous studies in the lab of Amy Bastian, PhD, PT, director of the Motion Analysis Laboratory at Kennedy Krieger Institute, have shown that the cerebellum, a part of the brain involved in movement coordination, is essential for walking adaptation.

In this new study, Dr Bastian and her colleagues explored the impact of stimulation over the cerebellum on adaptive learning of a new walking pattern. Specifically, her team tested how anode (positive), cathode (negative) or sham (none) stimulation affected this learning process.

‘We’ve known that the cerebellum is essential to adaptive learning mechanisms such as reaching, walking, balance and eye movements,’ said Dr Bastian. ‘In this study, we wanted to examine the effects of direct stimulation of the cerebellum on locomotor learning utilising a split-belt treadmill that separately controls the legs.’

The study, published today in the Journal of Neurophysiology, found that by placing electrodes on the scalp over the cerebellum and applying very low levels of current, the rate of walking adaptation could be increased or decreased.

Dr Bastian’s team studied 53 healthy adults in a series of split-belt treadmill walking tests. Rather than a single belt, a split-belt treadmill consists of two belts that can move at different speeds. During split-belt walking, one leg is set to move faster than the other, initially disrupting coordination between the legs.

The main experiment consisted of a two-minute baseline period of walking with both belts at the same slow speed, followed by a 15-minute period with the belts at two separate speeds. While people were on the treadmill, researchers stimulated one side of the cerebellum to assess the impact on the rate of re-adjustment to a symmetric walking pattern.

Dr Bastian’s team found not only that cerebellar tDCS can change the rate of cerebellum-dependent locomotor learning but, specifically, that the anode speeds up learning and the cathode slows it down. It was also surprising that the side of the cerebellum that was stimulated mattered; only stimulation of the side that controls the leg walking on the faster treadmill belt changed adaptation rate.

‘It is important to demonstrate that we can make learning faster or slower, as it suggests that we are not merely interfering with brain function,’ said Dr Bastian. ‘Our findings also suggest that tDCS can be selectively used to assess and understand motor learning.’