신문지로, 파리채로 탁! 파리 잡기 성공률 떨어지는 이유 Do Flies Have Fear (Or Something Like It)?

美 캘리포니아공대,

“그림자 생기면 두려움 느끼고 날아가”

미 캘리포니아공대 연구팀이 사용한 실험장치. 검은 주걱 모양의 물체가 

움직이며 그림자를 만든다. - 미 캘리포니아공대 제공

출처 동아사이언스

edited by kcontents 

케이콘텐츠 편집

파리 한 마리가 벽에 앉은 것을 발견했다. 옆에 있던 신문지를 들고 살며시 파리 위에 놓고 내리치려는 순간, 파리는 훌쩍 날아가 버렸다. 최근 미국 캘리포니아공대(Caltech) 연구팀은 파리가 신문지나 손바닥의 위협을 미리 알아채고 도망갈 수 있는 비결을 밝혔다. 파리가 신문지나 손바닥이 가까워질 때 생기는 그림자를 감지한다는 것이다.   연구팀은 초파리를 통에 가둬두고 초파리 위로 그림자를 드리울 수 있는 실험 장치를 만들었다. 그리고 통 속에 사는 초파리의 행동을 녹화한 뒤 이를 분석했다.   그 결과 초파리는 그림자가 드리울 때 이상행동을 보였다. 평소보다 빨리 총총 뛰거나 그대로 얼어붙기도 했다. 음식을 먹고 있는 파리에게도 그림자를 드리우면 역시 이상 반응을 나타냈다. 원래 배고픈 파리는 음식을 그때그때 받아먹지만 그림자가 드리우면 순간 동작을 멈추고 얼어붙는 등 이상행동을 한 뒤 그림자가 없어진 뒤에야 음식을 먹었다.   초파리의 이상행동 중에서 얼어붙는 행위는 개구리를 비롯한 척추동물이 두려움을 느낄 때 나타내는 행동이다. 연구팀은 이를 토대로 그림자가 드리울 때 파리가 두려움을 느끼는 것 같다고 추정했다. 이 두려움은 사람의 공포심과 비슷한 감정이다.    연구팀은 이번 연구로 그동안 유전학에서 모델생물로 큰 활약을 한 초파리가 신경계 연구에서도 좋은 모델동물로 쓰일 수 있을 것으로 예상했다.   연구 결과는 ‘커런트 바이올로지’ 14일자에 실렸다. 동아사이언스 신선미 기자 vamie@donga.com

Do Flies Have Fear (Or Something Like It)?

When fruit flies respond to the threat of an overhead shadow, are they afraid? That's a hard question to answer, say researchers reporting in the Cell Press journal Current Biology on May 14. However, their studies do show that flies' response to visual threats includes many essential elements of what we humans call fear. David J. Anderson of the Howard Hughes Medical Institute and the California Institute of Technology and his colleagues say that their findings in flies are a step toward dissecting the fundamental neurochemistry, neuropeptides, and neural circuitry underlying fear and other emotion states. "No one will argue with you if you claim that flies have four fundamental drives just as humans do: feeding, fighting, fleeing, and mating," says William T. Gibson, a Caltech postdoctoral fellow and first author on the study. "Taking the question a step further--whether flies that flee a stimulus are actually afraid of that stimulus--is much more difficult." To ask the question in a different and less problematic way, the researchers dissected fear into its fundamental building blocks, which they refer to as "emotion primitives." First, fear is persistent, Gibson explains. If you hear the sound of a gun, the feeling of fear it provokes will continue for a period of time. Fear is also scalable; the more gunshots you hear, the more afraid you'll become. Fear is generalizable across different contexts, but it is also trans-situational. Once you're afraid, you're more likely to respond in fear to other triggers: the clang of a pan, for instance, or a loud knock at the door. The question then was this: In terms of these building blocks of emotions, does a fly's response to shadows resemble our response to the sound of a gun? Very much so, the new study shows. Anderson and colleagues came to that conclusion after enclosing flies in an arena where they were exposed repeatedly to an overhead shadow. In collaboration with Pietro Perona's computer vision group, also at Caltech, the team carefully analyzed the flies' behaviors as captured on video, which showed that shadows promoted graded and persistent increases in the flies' speed and hopping. Occasionally, the insects froze in place, a defensive behavior also observed in the fear responses of rodents. The shadows also caused hungry flies to leave a food source, suggesting that the experience was generally negative and generalized from one context to another. It took time before those flies would return to their food following their dispersal by the shadow, suggesting a slow decay of the insects' internal, defensive state. Importantly, the more shadows the flies were exposed to, the longer it took for them to "calm down" and return to the food. In other words, when flies flee in response to a shadow, it's more than a momentary escape. It's a lasting physiological state much like fear. And, if that's true, it means that flies could help us understand in a very fundamental way what fear and other emotions are made of. "The argument that this paper makes is that the Drosophila system may be an excellent model for emotion states due to the relative simplicity of its nervous system, combined simultaneously with the behavioral complexity it exhibits," Gibson says. "Such a simple system, leveraged with the power of neurogenetic screens, may make it possible to identify new molecular players involved in the control of emotion states." The next step, the researchers say, is to dissect the neural circuitry involved in the flies' shadow response. http://www.sciguru.org/newsitem/19054/do-flies-have-fear-or-something-it

edited by kcontents

"from past to future"

데일리건설뉴스 construction news

콘페이퍼 conpaper 

.