Is it possible to permanently change your memories? A group of scientists think so. And their new techniques for altering memories are raising possibilities of one day treating people who suffer from phobias, post-traumatic stressdisorder and other anxiety-related conditions.

Some researchers are working with combatveterans, car-accident survivors and rape victims to replace their memories with less fear-filled ones using a familiar hypertension drug. Other scientists are studying whether behavioral therapy can one day be used to modify memories of people who react with fear to common anxiety-producing events. A person bitten by a dog as a child, for instance, might be able to overcome a canine phobia if the old memory can be replaced with a less scary one.

The goal of the research isn't to erase memory outright, as depicted in popular movies over the years. That would raise ethical issues and questions of what would happen to associated memories, scientists say. Instead, 'reducing or eliminating the fear accompanying the memory . . . that would be the ideal scenario,' says Roger Pitman, a psychiatry professor at Harvard Medical School who has done extensive work in this area.

The latest research is based on a radical rethinking of how memories are stored in the brain. Scientists used to believe memories are like snapshots on which the details are fixed once they're recorded. Now, many experts accept the view that memories are stored like individual files on a shelf; each time they are pulled down for viewing, they can be altered before being put back into storage. Altering a memory during the time it is off the shelf can create an updated memory that can be saved in place of the old one, scientists believe.

Sometimes a traumatic incident can trigger an enduringresponse of fear whenever the incident is recalled, even indirectly. A car backfiring, for instance, can set off an emotionalresponse in a combatveteran if the loud noise becomes associated in his mind with a wartime experience.

A common therapy currently for trauma and phobias is called exposuretreatment. It involves repetitive exposure in a nonthreatening way to help patients confront their fears and gradually weaken the fear response, a process known as extinction. But with extinction, the fearful memories don't disappear or get altered, and relapse is common, says Edna Foa, an expert on post-traumatic stressdisorder at the University of Pennsylvania School of Medicine. If extinction could be enhanced, that could mean more efficienttreatment with less relapse, she says.

Researchers are hoping new techniques will weaken the fear response for a longer period, or perhaps permanently. The trick, they say, is to administer the treatment after the original memory has been retrieved from storage so the updated memory will be saved. One way of doing this is to have the subject write a detailed account of the original incident and reread it at the start of each treatment session.

Shirley S. Wang

• stress [stres] n.强调；压力 vt.强调 (初中英语单词)
• working [´wə:kiŋ] a.工人的；劳动的 (初中英语单词)
• replace [ri´pleis] vt.放回；复置；取代 (初中英语单词)
• instance [´instəns] n.例子，实例，例证 (初中英语单词)
• overcome [,əuvə´kʌm] vt.战胜，克服 (初中英语单词)
• research [ri´sə:tʃ] n.&vi.调查；探究；研究 (初中英语单词)
• medical [´medikəl] a.医学的；医疗的 (初中英语单词)
• extensive [ik´stensiv] a.广阔的；大量的 (初中英语单词)
• incident [´insidənt] n.小事件；事变 (初中英语单词)
• whenever [wen´evə] conj.&ad.无论何时 (初中英语单词)
• emotional [i´məuʃənəl] a.易动感情的；情感的 (初中英语单词)
• treatment [´tri:tmənt] n.待遇；对待；治疗 (初中英语单词)
• fearful [´fiəfəl] a.可怕的；担心的 (初中英语单词)
• expert [´ekspə:t] n.&a.专家；内行 (初中英语单词)
• account [ə´kaunt] vi.说明 vt.认为 n.帐目 (初中英语单词)
• disorder [dis´ɔ:də] n.杂乱 vt.扰乱 (高中英语单词)
• combat [´kɔmbæt] v.&n.斗争；战斗；争斗 (高中英语单词)
• harvard [´hɑ:vəd] n.哈佛大学 (高中英语单词)
• radical [´rædikəl] a.根本的；主要的 (高中英语单词)
• storage [´stɔ:ridʒ] n.贮存；存储器 (高中英语单词)
• response [ri´spɔns] n.回答；响应 (高中英语单词)
• veteran [´vetərən] n.老兵 a.老练的 (高中英语单词)
• exposure [ik´spəuʒə] n.暴露；曝光(时间) (高中英语单词)
• confront [kən´frʌnt] vt.(使)面对；正视 (高中英语单词)
• weaken [´wi:kən] v.(使)弱化；衰弱；稀薄 (高中英语单词)
• efficient [i´fiʃənt] a.有效的，有能力的 (高中英语单词)
• administer [əd´ministə] vt.管理；支配；执行 (高中英语单词)
• permanently [´pə:mənəntli] ad.永久地；持久地 (英语四级单词)
• bitten [´bitn] bite的过去分词 (英语四级单词)
• trigger [´trigə] n.扳机 vt.触发，启动 (英语六级单词)
• enduring [in´djuəriŋ] a.持久的 (英语六级单词)
• indirectly [,indi´rektli] a.间接地；迂回地 (英语六级单词)