C A decline in memory as a result of ageing can be temporarily reversed using a harmless form of electrical brain stimulation, scientists have found. The study focused on a part of cognition called working memory, the brain system that holds information for short periods while we are making decisions or performing calculations. Working memory is crucial for a wide variety of tasks, such as recognising faces, doing arithmetic and navigating a new environment. Working memory is known to steadily decline with age. One factor in this decline is thought to be a disconnection between two brain networks. In the study, published in the journal Nature Neuroscience, 42 people aged 20-29 and 42 people aged 60-76 were assessed in a working memory task. The older group were slower and less accurate on the tests. The scientists then subjected them all to 25 minutes of non-invasive brain stimulation. This aimed to make the two target brain regions work together by passing gentle pulses of electricity through the scalp(头皮)and into the brain. After the treatment， working memory in the older adults improved to match the younger group and the effect appeared to last for 50 minutes after the stimulation. Those who had scored worst to start with showed the largest improvements. While these results were exciting and promising. Dardo Tomasi, a scientist at the National Institute on Alcohol Abuse and Alcoholism in Bethesda, who was not involved in the work said that larger studies would be needed to confirm the findings and assess how they might be applied clinically. D. James Picket e head of research at the Alzheimer's Society, said, “We can’t cure, prevent or even slow down dementia (痴呆 )，so it vital we explore all possible areas for treatments. Altering and correcting the circuitry of the brain with technology is a new exciting avenue of research for dementia. Deep-brain simulation a surgical procedure used in Parkinson’s, is proof of principle that this approach may one day be frui
A.To emphasize the importance of various tasks
B.To introduce the decisions of the brain system
C.To describe the connection of brain networks
D.To present the functions of working memory