2022年考博英语阅读篇章材料(29)

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　　When the Head Rules the Heart

　　Some heart attacks may be all in your head. Scientists in Canada have found

　　a region in the brain that may control the ac- tivity of the heart and blood

　　vessels. They say that abnormalities in this region could account for the

　　hundreds of thousands of otherwise unexplained cardiac arrests? that occur

　　every year.

　　Andrew King, David Cechetto and their colleagues at the University of

　　Western Ontario in London reported at the meeting that they asked five subjects

　　to carry out simple tasks that raise blood pressure. For instance, they were

　　told to squeeze a cylinder as tightly as possible, or hold their breath for

　　several seconds. As they did this, the researchers monitored the subjects' blood

　　pressure and heart rate throughout.

　　The team then asked all the subjects to repeat the tasks while in a

　　high-resolution functional magnetic resonance? brain scanner, and watched

　　which areas of the brain the tasks activated. It turned out that all the tasks

　　activated a spot in the insular cortex, which is tucked inside a fold in the

　　brain just above ear level.

　　The researchers suspect that the insular cortex controls the heart and

　　blood vessels. This theory would fit in with a study Cechetto carded out several

　　years ago, which showed that a region of cardiovascular control exists in rats'

　　brains. By elec- trically stimulating that region, he could alter the heart

　　rate, and even bring about lethal cardiac arrhythmia in the animals.

　　King and Cechetto believe that many unexplained heart at- tacks could be

　　due not simply to the traditional factors like poor diet and clogged arteries,

　　but to abnormalities in the brain's cardiovascular control center. “They may

　　have a neural basis,” King told New Scientist. “There are people who run all the

　　time, eat well, and yet they end up dying.”

　　The unexplained heart attacks include those that afflict about 6 per cent

　　of all stroke patients, even though they have no history of heart problems. King

　　speculates that the attacks arise because their strokes may have damaged the

　　brain's cardiovascu- lar site.

　　This is the first time that a higher brain region that controls internal

　　organs has been identified in humans. The researchers say they would like to

　　know what their new results say about the link between stress and heart disease.

　　It is well known that anger. and stress play a major role in sudden cardiac

　　death, ether- sclerosis, heart attacks and strokes, but exactly why this happens

　　is unclear.

　　The team says that their results might lead to ways of pre- venting many

　　heart attacks. They hope to find out if people whose heart rates and blood

　　pressure increase dramatically in response to stress also have more activation

　　in these brain areas—and whether heart attacks apparently caused by stress and

　　anger might be triggered in these regions. “There are definite clinical

　　applications.” says King.

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