Back in 2009, two researchers from the Department of Neurology at the Freiburg University Medical Centre were able to show during their research stay in the USA that the repeated stimulation of the brain with weak direct current increases the brain’s ability to acquire new complex motor skills. The researchers have now investigated the underlying mechanisms and published the results in the current issue of the renowned scientific journal Neuron.
The scientists used primary motor cortex (M1) slices of mice to show that the strength of synaptic transmission, i.e. the communication between nerve cells, increases considerably during a 15-minute charge-dependent stimulation with direct current (DCS). This effect continued for more than two hours after stimulation had ended. The long-lasting enhancement of synaptic potentiation of the brain is seen as the cellular correlate of motor skill learning and memory. In addition, the team showed that certain conditions had to be fulfilled in order for DCS to have an effect: amongst other things, the coupling of DCS with repetitive low-frequency synaptic activation of the nerve cells and the release of neurotrophic factors known as “brain-derived neurotrophic factors” (BDNF).Experiments involving healthy volunteers and mice showed that activity-dependent secretion of BDNF impairs motor skill acquisition: approximately one third of the human population have a point mutation in the BDNF gene, which results in a 30 per cent reduction of the activity-dependent secretion of BDNF. This can also be achieved in transgenic mice. The study published in Neuron shows that the mutation in the BDNF gene in both humans and mice considerably impedes the acquisition of motor skills. Fortunately, the charge-dependent DC stimulation had a positive effect on the success of learning as long as BDNF was present. The Freiburg researchers believe that their new findings on the mechanisms of motor skill acquisition and DCS can open up possibilities of developing targeted rehabilitative therapies for patients who have suffered strokes or who have other types of brain damage. The study entitled “Direct current stimulation promotes BDNF-dependent synaptic plasticity: Potential implications for motor learning” is available at www.neuron.org.
Contact:Dr. Brita Fritsch and Dr. Janine ReisDepartment of NeurologyFreiburg University Medical CentreTel.: +49 (0)761/270-5001E-mail: firstname.lastname@example.org oderjanine.reis(at)uniklinik-freiburg.de