VOA健康报道2024--Study: How the Brain Cleans Itself

From VOA Learning English, this is the Health & Lifestyle report.

A rare look inside the human brain might help to explain how it clears away waste. Scientists say the failure to clear away such waste can lead to Alzheimer's disease and other brain disorders².

Brain cells use a lot of nutrients³. This means they produce a lot of waste. Scientists believe the brain has special structures to take out this "cellular⁴ trash," especially during sleep. They have reported observing this process happening in mice. But they had no clear evidence that this happens in humans.

Recently published research appears to have identified a system, or network, of very small waste-clearing channels in the brains of living humans. The researchers used a special kind of imaging technology to study the network.

One of the researchers was Dr. Juan Piantino of Oregon Health & Science University. Piantino said the new research was important evidence. "We needed this piece to say this happens in humans, too," he said.

His team recently published its findings in Proceedings⁵ of the National Academy of Sciences.

The brain is very active during sleep. During sleeping hours, the brain appears to clean itself.

That idea has gotten the attention of researchers. Losing a good night's sleep can cause people's thinking to be unclear. But a continuous lack of sleep is believed to increase the risk of the brain disorder¹ dementia.

How does the brain clean itself?

Over 12 years ago, scientists at the University of Rochester first reported finding a network they named the "glymphatic system." Fluid from the brain, called cerebrospinal fluid, travels through channels surrounding blood vessels⁷ to carry waste out of the brain.

Beta-amyloids are substances linked to problems in the brain including Alzheimer's disease. When scientists injected mice with beta-amyloids, the substance left the brain faster when the animals were sleeping.

It is not clear exactly how the system works. However, some research has shown that the movement of blood vessels might help move the waste-clearing fluid where it needs to go.

Finding the system in humans is not easy. Regular MRI scans can show some of the fluid-filled channels. But Piantino said the scans do not show their purpose.

To find out more, his team at Oregon Health & Science University injected a substance called a tracer into five patients. The tracer "lit up" during MRI scans. Twenty-four to 48 hours later, the tracer material was seen moving through the brain using the channels as in the earlier research on mice.

Rochester's Dr. Maiken Nedergaard predicts that the study will increase interest in how brain waste clearance⁸ connects to people's health.

But to test if better sleep or other treatments might really increase waste clearance and improve health, researchers "have to be able to measure glymphatic function in people," said Dr. Jeff Iliff. He is with the University of Washington and has helped lead waste-clearance research. The question is whether the new study might point to ways of measuring the process.

Sleep is not the only question. For example, animal studies show that a blood pressure drug now used to treat the stress disorder called PTSD might improve glymphatic clearing. Iliff and Dr. Elaine Peskind plan to study this drug in a group of patients.

Larger studies in healthy people are also needed.

In addition, Piantino, who used tracer chemicals in people, wants to find an easier, noninvasive test to follow the waste clearance.

"We cannot study all the questions by injecting people," he said.

Words in This Story

trash -n. waste materials, especially household waste

network -n. an interconnected group of pathways, wires or links

channel -n. a pathway for fluid

blood vessel⁶ -n. any of a group of tubes made from tissue that carry blood throughout the body

MRI scan (magnetic resonance⁹ imaging) -n. a technology that uses electromagnetism to create images of tissue inside the body

tracer -n. a substance that has a chemical or radioactive property that permits it to be observed inside the body of a living thing

noninvasive -n. a way of looking inside the body without using a medical operation or placing a device in the body

1 disorder   

n.紊乱，混乱；骚动，骚乱；疾病，失调

参考例句：

• When returning back,he discovered the room to be in disorder.回家后，他发现屋子里乱七八糟。
• It contained a vast number of letters in great disorder.里面七零八落地装着许多信件。

2 disorders   

n.混乱( disorder的名词复数 )；凌乱；骚乱；（身心、机能）失调

参考例句：

• Reports of anorexia and other eating disorders are on the increase. 据报告，厌食症和其他饮食方面的功能紊乱发生率正在不断增长。 来自《简明英汉词典》
• The announcement led to violent civil disorders. 这项宣布引起剧烈的骚乱。 来自《简明英汉词典》

3 nutrients   

n.（食品或化学品）营养物，营养品( nutrient的名词复数 )

参考例句：

• a lack of essential nutrients 基本营养的缺乏
• Nutrients are absorbed into the bloodstream. 营养素被吸收进血液。 来自《简明英汉词典》

4 cellular   

adj.移动的；细胞的，由细胞组成的

参考例句：

• She has a cellular telephone in her car.她的汽车里有一部无线通讯电话机。
• Many people use cellular materials as sensitive elements in hygrometers.很多人用蜂窝状的材料作为测量温度的传感元件。

5 proceedings   

n.进程，过程，议程；诉讼(程序)；公报

参考例句：

• He was released on bail pending committal proceedings. 他交保获释正在候审。
• to initiate legal proceedings against sb 对某人提起诉讼

6 vessel   

n.船舶；容器，器皿；管，导管，血管

参考例句：

• The vessel is fully loaded with cargo for Shanghai.这艘船满载货物驶往上海。
• You should put the water into a vessel.你应该把水装入容器中。

7 vessels   

n.血管( vessel的名词复数 )；船；容器；（具有特殊品质或接受特殊品质的）人

参考例句：

• The river is navigable by vessels of up to 90 tons. 90 吨以下的船只可以从这条河通过。 来自《简明英汉词典》
• All modern vessels of any size are fitted with radar installations. 所有现代化船只都有雷达装置。 来自《现代汉英综合大词典》

8 clearance   

n.净空；许可(证)；清算；清除，清理

参考例句：

• There was a clearance of only ten centimetres between the two walls.两堵墙之间只有十厘米的空隙。
• The ship sailed as soon as it got clearance. 那艘船一办好离港手续立刻启航了。

9 resonance   

n.洪亮；共鸣；共振

参考例句：

• Playing the piano sets up resonance in those glass ornaments.一弹钢琴那些玻璃饰物就会产生共振。
• The areas under the two resonance envelopes are unequal.两个共振峰下面的面积是不相等的。