Even able-bodied people initially find it quite difficult to learn precisely linked small movements. The brain of a child attempting to raise a cup of tea or juice to his or her mouth to take a drink needs to integrate different types of information: for example feedback from the hand and arm muscles and visual information about the temporary position of the cup. Nerve cells have to learn to fire in a precisely defined pattern and new connections have to be created. Feedback loops will gradually develop to mediate the smooth succession of individual movements. Stroke patients experience far greater difficulties. Extensive parts of these feedback loops may be damaged and therefore need to be re-established. This is difficult because the brain tissue of adults is no longer as plastic as that of children. Dr. Janine Reis from the Department of Neurology at the Freiburg Medical School works with both healthy and sick people and is trying to jog their memory in a rather unconventional way, namely using electrical stimulation.

“I have recently returned from living in the USA where I did a scientific project on this topic,” said Reis. Janine Reis, who was born in Haan (North Rhine-Westphalia) in 1977, studied medicine at the University of Marburg and did her doctorate on epileptic disorders where she first became interested in neuroscientific research. Her doctoral thesis focused on how anti-epileptic drugs affect the excitability of the brain. Reis used non-invasive stimulation methods, which means that she manipulated the electrical impulses in the brain of probands with a magnetic field whilst at the same time preventing the field from entering the brain and damaging the tissue. She continued her work at the National Institute for Neurological Disorders and Stroke (NINDS) near Washington D.C., using electrodes attached to the brain skin. Her two-year stay at the NINDS was made possible thanks to an Alexander von Humboldt Foundation grant which she received during her residence in Marburg; a visiting fellow award from the National Institutes of Health (NIH) covered another nine months of her stay in the USA.

Reis was attempting to find out whether people acquire motor skills more effectively when their brain is stimulated electrically during learning. "Several papers had been published on the subject," said Reis. "But unfortunately no long-term studies were available." She then designed experiments where current was applied during the learning period aimed at finding out whether the tasks could be recalled three months later.

She used what is known as anodal transcranial direct current stimulation (tDCS) in which DC generated by an anode excites the motor area of the cortex. Over five consecutive days, volunteers were asked to move a cursor over a computer screen and change its direction by pressing a power transmitter. "This is not a trivial task," said Reis. "It requires the input of the eyes and then the muscles. We measured the visuomotoric capabilities of the subjects on a daily basis." Further tests over a period of three months were carried out to find out how well the volunteers recalled the acquired capabilities after a longer period of time.

People whose motor cortex was stimulated with an electrode during the experiments, were quicker in learning the tasks and more exact than the control group who were treated with sham tDCS. “The paradox was that the subjects did not learn best at the actual moment they were doing the tasks,” explained Reis. “The learning effect was generated at night as it was shown that the electrode subjects forgot far less of what they had acquired than those who had not been electrically stimulated.” Electrical stimulation thus contributed to consolidating the acquired motor skills. Long-term studies showed that the subjects who were exposed to electrical current during learning were quicker and more exact in performing the acquired tasks than the control group. Although both groups forgot the motor skills they had acquired very rapidly after 3 months had passed, the recall of volunteers exposed to tDCS was better and their overall performance was a lot higher than the subjects who had been exposed to sham tDCS.

Reis has been assistant doctor in the Department of Neurology at the Freiburg Medical School for five months now and hopes to finish her medical specialist training soon. She is also very excited about her future research projects. “Freiburg is not just an exciting city, but also one of the major imaging centres in Germany,” said Reis. “In addition, Freiburg is home to a large number of experts, which is exactly what is needed to undertake interdisciplinary projects.” Reis and her colleague, Dr. Brita Fritsch, are planning to carry out cell biology animal experiments to find out why tDCS leads to a better acquisition of motor skills. In addition, Reis also plans to use imaging methods to find out what happens in the brain of human volunteers during stimulation. She has already commenced investigations involving stroke patients because for her, the greatest potential of the non-invasive stimulation method lies in clinical applications. “We are currently testing whether the stimulation of stroke patients has similar effects. Maybe we will be able to use our method to treat patients in about five to ten years’ time,” said Reis.

Further information:
Dr. Janine Reis
Department of Neurology
Freiburg Medical School
Breisacher Str. 64
Tel.: +49 (0)761/270-5154
E-mail: janine.reis@uniklinik-freiburg.de