2014英语四级听力练习慢速(1)

　　英语四级听力练习：慢速 Study Finds Caffeine May Help Enhance Long-term Memory 点击收听

　　原文：

　　From Learning English, this is the Health Report.

　　Many people say they can not start their day without first having a cup of coffee or tea. People say these drinks help them think clearly and feel more awake. This is because of caffeine, a substance found in some plants.

　　Caffeine helps to give a jumpstart to the nervous system. Now a new report says it may also improve long-term memory. The report was published earlier this year in the journal Nature Neuroscience.

　　Michael Yassa is a neurobiology professor at the University of California, Irvine. He and other researchers wanted to know if caffeine could improve what they called memory consolidation. They asked a group of individuals to learn something new, then the same people were given caffeine, the active ingredient in coffee, tea and chocolate.

　　He and the other researchers worked with a group of 160 people who were caffeine free. On the first day, all the subjects were shown pictures of everyday objects. They were asked to identify whether the pictures could be found inside the house or outdoors. Some of the subjects were then given a caffeine pill, the others were given a placebo - a pill containing an inactive substance.

　　On the second day, all of the subjects were asked to look at more pictures. Some of the images were exactly like the ones they had seen 24 hours early. But other images were different. And a third group of pictures was similar to the first group but a little different. The participants had to decide whether the images they saw were the same or different from the ones on the first day.

　　Professor Yassa says their answers help to show the effects of caffeine on memory.

　　He says those who took the caffeine pills had a ten to twelve percent increase in their ability to remember the objects. The amount of caffeine the researchers used in the study was similar to one strong cup of coffee.

　　Professor Yassa says pills with a little more coffeine also increased memory, but resulted in some participants appearing more nervous.

　　And thats the Health Report from Learning English. For more stories about health, go to our website 51voa.com. Im Christopher Cruise.