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Professor Shimamura identified a number of areas in which mental function may change.
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Scientists now understand why people's mental faculties decline at different rates.
Professor Arthur Shimamura, of the University of California at Berkeley, says there are three main ways in which mental function changes. The first is mental speed, for example how quickly you can react to fast-moving incidents on the road. Drivers in their late teens react quickly but tend to drive too fast, while the over sixties are more cautious but react more slowly. The near-inevitable slowing with age also partly explains why soccer players are seen as old in their thirties, while golf professionals are still in their prime at that age. This type of mental slowing results from a reduction in the efficiency with which the brain's neurons work.
The fact that adults find it harder to learn musical instruments than children points to a second type of mental loss with age—a reduction in learning capacity. The parts of the brain known as the temporal lobes control new learning, and are particularly vulnerable to the effects of aging. This means that, as we get older, we take longer to learn a new language, are slower to master new routines and technologies at work, and we have to rely more on diaries and other mental aids.
'Working memory' is the third brain system which is vulnerable to the effects of aging. Working memory is the brain's 'blackboard', where we juggle from moment to moment the things we have to keep in mind when solving problems, planning tasks and generally organizing our day-to-day life. Absent-mindedness occurs at all ages because of imperfections in the working memory system—so, for instance, you may continually lose your glasses, or find yourself walking into a room of your house only to find that you cannot remember what you came for.
Such absent-mindedness tends to creep up on us as we age and occurs because our plans and intentions, which are chalked up on the mental blackboard, are easily wiped out by stray thoughts and other distractions. Stress and preoccupation can also cause such absent-mindedness, in addition to age-related changes in the brain. The frontal lobes of the brain—located behind the forehead and above the eyes are where the working memory system is located. Like the temporal lobes, which handle new learning, the frontal lobes are more vulnerable to the aging process than other parts of the brain.
The news, however, is not all bleak. Although neurons reduce in number with age, the remaining neurons send out new and longer connecting fibres(dendrites) to maintain connections and allow us to function reasonably well with only relatively small drops in ability.
This and other evidence suggests that the principle 'use it or lose it' might apply to the aging brain. Professor Shimamura studied a group of university professors who were still intellectually active, and compared their performance on neuropsychological tests with that of others of their age group, as well as with younger people. He found that on several tests of memory, the mentally active professors in their sixties and early Seventies were superior to their contemporaries, and as good as the younger people.
Research on animals provides even stronger evidence of the effects of stimulation on the brain structure. Professor Bryan Kolb, of the University of Lethbridge in Canada, has shown that animals kept in stimulating environments show sprouting(生长) and lengthening of the connecting nerve fibres in their brains, in comparison With animals kept in unstimulating environments.
The beneficial effects of continued mental activity are shown by the fact that older contestants in quiz shows are just as fast and accurate in resp
Research indicates that physical training can help to improve memory.
No matter how large or notable(著名的) the U.S. travel industry is or may become, it will always be members of a broader world society. The charge facing all of us is to appropriately engage poverty. Poverty is certainly not new but the means at our disposal to address poverty are improving by the day. Fortunately, the $3.3 trillion world travel industry is uniquely suited to address poverty in regions where it is most entrenched. In the course of making a case for harnessing travel and tourism for poverty reduction, the travel and tourism industry already exists in every region of the globe and is a proven job producer and sustainer of native culture.
That travel and tourism creates good jobs is indisputable. In the U.S., the industrial Age economy is in transition(过渡) to a service economy, and travel and tourism is responsible for one in every seven workers in the U.S. civilian workforce, directly or indirectly. But by no means is this phenomenon limited to the U.S. The World Travel and Tourism Council reports tourism employs almost 200 million people worldwide—1 in every 13 jobs worldwide today.
There are many important differences between building an industrial based economy and one that relies largely on tourism. One of the historical barriers to industrialization has been a shortage of capital to build an industrial infrastructure or a lack of industrial-specific facilities such as deep-water ports. But we don't need to build factories for tourism. Nor do we need the traditional resources of the Industrial Age to build new tourism economies. The essential raw materials for our industry include rich cultures, unique natural environments and willing hosts. And those raw materials exist already in abundance(丰富) in every nation.
Only travel brings us face to face with. people from different cities, different nations, and different outlooks. CNN can take us on a virtual world tour. We can be touched by images we see in the media but it is only when we shake hands with people from other nations and other cultures that we learn how things really are. And despite the many wonders of technology, we only truly touch one another when we travel and embrace one another's culture, stature, and dreams.
From the first paragraph we learn that the travel industry ______.
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