学生啦：课时作业（三）Unit 1SectionⅢExtended reading Project&Further study阅读理解AIn 2015,researchers from Australia's Deakin University published one of the first studiesmeasuring food's physical effect on the left hippocampus(海马体)，a seahorse-shaped brainregion crucial for memory,leaming,and decision making.It is also one of the first areas to shrinkin people with Alzheimer's disease and other forms of dementia ()255 people filled out dietsurveys and then underwent MRI(磁共振扫描成像)that measured their brains.Four years later,they returned for another scan in response to a request from the researchers.The study found that the left hippocampus was bigger and heavier in the healthy eaters thanin the unhealthy ones,regardless of age,sex,weight,exercise habits,or general health.Thatmeans eating the right foods and skipping the wrong stuff could help protect against declines inthinking and memory that lead to dementia.Healthy eating doesn't just prevent brain decline.Itraises scores on thinking and memory tests,according to a study published in March 2019 thattracked 2,621 American women and men for 30 years."Green leafy vegetables have goodeffects that may protect both females and males against cognitive (decline and dementia,"says lead researcher Claire McEvoy,RD,of the Centre for Public Health at Queen's UniversityBelfast in Northern Ireland.Even a little healthy food goes a long way.According to a 2018 Rush University study thattracked 960 people for 4.7 years,participants who ate just 1.3 extra servings of green leafyvegetables a day showed cognitive abilities similar to those of people 11 years younger.How are these power foods working with your brain cells?Animal and test-tube experimentssuggest that compounds in healthy diets help new cells make copies of DNA when they divide andmultiply.Meanwhile,high-fat,high-sugar processed foods harm brain cells.While food serves as an important brain protector,experts say brain supplements (aren't all that effective.Studies show that they don't make brain cells active in a significantlypositive way."Let the buyer be cautious,says David Hogan,MD,a specialist at theUniversity of Calgary.A study of nootropics (in the November 2019 Journal of theAmerican Medical Association revealed that the unapproved drug一piracetam(乙酰胺吡咯烷酮)was found in four out of five brands tested,at levels that could cause side effects such asdepression.1.Why did the researchers have the 255 people return for another MRI scan four years later?A.To test whether they had Alzheimer's disease.B.To see what effects diets had on the left hippocampus.C.To study how they kept healthy in the four years.D.To deepen their research into Alzheimer's disease.2.What can we infer from Paragraph 2?A.Healthy eating helps to reduce the risk of dementia.