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自分が読んで興味深く感じた英文記事を中心に取り上げる予定です

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英検長文問題対策〜記憶をめぐって〜(1)

 
英検というタイトルは釣りにすぎませんが、評価が定まっていないトピックは英検でもよく出ますので、今回紹介するような記事をじっくり考えながら読むことは間接的ながらも役立つに違いありません。

以前このブログで紹介させていただいた雑誌ScienceのMITの利根川進先生の研究が今週のNatureでも取り上げられていました。この記事では脳研究の倫理的な問題を扱っています。

US brain project puts focus on ethics
Unsettling research advances bring neuroethics to the fore.
Helen Shen
14 August 2013

The false mouse memories made the ethicists uneasy. By stimulating certain neurons in the hippocampus, Susumu Tonegawa and his colleagues caused mice to recall receiving foot shocks in a setting in which none had occurred1. Tonegawa, a neuroscientist at the Massachusetts Institute of Technology in Cambridge, says that he has no plans to ever implant false memories into humans — the study, published last month, was designed just to offer insight into memory formation.

But the experiment has nonetheless alarmed some neuroethicists. “That was a bell-ringer, the idea that you can manipulate the brain to control the mind,” says James Giordano, chief of neuroethics studies at Georgetown University in Washington DC. He says that the study is one of many raising ethical concerns, and more are sure to come as an ambitious, multi-year US effort to parse the human brain gets under way.

来週の火曜日に大統領主催の生命倫理の諮問会議が開かれることもあり、記事になっているようです。こういう問題の線引きは難しそうですよね。

On 20 August, US President Barack Obama’s commission on bioethics will hold a meeting in Philadelphia, Pennsylvania, to begin to craft a set of ethics standards to guide the BRAIN project. There is already one major mechanism for ethical oversight in US research: institutional review boards, which must approve any studies involving human subjects. But many ethicists say that as neuroscience discoveries creep beyond laboratory walls into the marketplace and the courtroom, more comprehensive oversight is needed. “The long-term consequences of more brain knowledge — whether it’s good for an ethnic group or threatens your personal identity — there’s sort of no one in charge of that,” says Arthur Caplan, director of medical ethics at New York University’s Langone Medical Center.

今回のNatureの記事のおかげで、利根川先生の実験の重要性をようやく理解できた気がします。重要性の評価は門外漢には難しい者ですね。

Science 26 July 2013:
Vol. 341 no. 6144 pp. 387-391
DOI: 10.1126/science.1239073
• REPORT
Creating a False Memory in the Hippocampus

Memories can be unreliable. We created a false memory in mice by optogenetically manipulating memory engram–bearing cells in the hippocampus. Dentate gyrus (DG) or CA1 neurons activated by exposure to a particular context were labeled with channelrhodopsin-2. These neurons were later optically reactivated during fear conditioning in a different context. The DG experimental group showed increased freezing in the original context, in which a foot shock was never delivered. The recall of this false memory was context-specific, activated similar downstream regions engaged during natural fear memory recall, and was also capable of driving an active fear response. Our data demonstrate that it is possible to generate an internally represented and behaviorally expressed fear memory via artificial means.

利根川先生のPodcastを改めて聞いてみると、単に記憶を研究室レベルで捉えているのではなく、謝った記憶を基に判決が決まってしまうことがあるという実践的な問題意識があるのが分かります。

スクリプト
Memory is usually a good guide for our current decisions, but under certain conditions, it could mislead us terribly. But 70% of defendants who have been found guilty primarily based on witnesses and the victim’s testimony were subsequently acquitted on the basis of a DNA test after serving many years in prison. However, studies on brain mechanism for false memory has been hampered because of the lack of an animal model. So in this study, we believe for the first time, succeeded in, we call this incepting or implanting

(中略)

I can give you one extraordinary example of a false memory. You know, there was a person apparently, I did not know him, but someone called Donald Thompson who is a psychiatrist and he had a TV show. A woman was watching this program, and all of a sudden a man broke in and raped her. After that terrible incident, she claimed it was this Donald Thompson who raped her even after she was told that Thompson was in the studio, but she was not convinced. Because in other words, she had real false memory of associating this guy Thompson with this terrible event of raping. In other words, her brain network made, just like this mouse, artificially associated two things that are not related. She liked this program. She was thinking about this program, and therefore, when she was thinking about it, the rape occurred and these two things got associated. So there are conditions which influence the relative strengths of our false and genuine memory, and we do not know very much about what parameters will influence how whole memory formation versus whole genuine memory formation. So we can study this, because we have a mouse model now.

判決における記憶の問題についてもNatureは記事にしていたので次の記事でご紹介します。
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