研究:电流刺激大脑可增强学习能力

　　Electrically stimulating the brain can help to speed up the process of learning, scientists have shown。

　　Applying a small current to specific parts of the brain can increase its activity, making learning easier。

　　Researchers from the University of Oxford have studied the changing structure of the brain in stroke patients and in healthy adults。

　　Prof Heidi Johansen-Berg presented their findings at the British Science Festival in Bradford。

　　The team at Oxford has been conducting research into how the structure of the brain changes in adulthood, and in particular what changes occur after a stroke。

　　They have used an approach called functional MRI to monitor activity in the brain as stroke patients re-learn motor skills that were lost as a result of their illness。

　　One of the major findings is that the brain is very flexible and can restructure itself, growing new connections and reassigning tasks to different areas, when damage occurs or a specific task is practised。

　　As part of this research, they investigated the possibility of using non-invasive electric brain stimulation to improve the recovery of these motor skills; the short-term improvement in stroke patients had already been noted。

　　But an unexpected result was found when the same brain stimulation was applied to healthy adults: their speed of learning was also significantly increased。

　　To observe this effect, the team devised an experiment whereby volunteers memorised a sequence of buttons to press "like playing a tune on a piano"。

　　While they were doing this, they were fitted with a "trans-cranial current stimulation" device, in which two electrodes are placed in a specific position on the head。

　　A very small current was passed between the electrodes in an arc through the brain and, depending on the direction of that current, either increased or decreased the activity of that part of the brain。

　　Prof Johansen-Berg explained that "an increase in activity of the brain cells makes them more susceptible to the kinds of changes that occur during learning"。

　　The results of the button-pressing experiments showed the positive effects of just 10 minutes of the brain stimulation on learning。

　　"While the stimulation didn't improve the participant's best performance, the speed at which they reached their best was significantly increased." said Prof Johansen-Berg。

　　In the treatment of stroke patients, the technique could be used in parallel with current physiotherapy treatments to improve overall outcomes, which tend to vary widely。