大脑感觉区域发育过程与预想不同-凯发k8官网

大脑感觉区域发育过程与预想不同
文章来源:未知 文章作者:enread 发布时间:2013-06-24 06:19 字体: [ ] 
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scientists at the salk institute for biological studies have demonstrated that 1 regions in the brain develop in a fundamentally different way than 2 thought, a finding that may yield new insights into visual and 3 4. in a paper published june 7, in science, salk researcher dennis o'leary and his colleagues have shown that 5 alone do not determine how the 6 cortex grows into separate 7 areas. instead, they show that 8 from the thalamus(丘脑), the main switching station in the brain for sensory information, is crucially required.
 
o'leary has done pioneering studies in "arealization," the way in which the neo-cortex, the major region of cerebral cortex, develops specific areas 9 to particular functions. in a 10 paper published in science in 2000, he showed that two regulatory genes were critically responsible for the general pattern of the neo-cortex, and has since shown distinct roles for other genes in this process. in this new set of mouse experiments, his laboratory focused on the visual system, and discovered a new, unexpected twist to the story.
 
"in order to function properly, it is essential that cortical areas are mapped out correctly, and it is this architecture that was thought to be 11 pre-programmed," says o'leary, 12 of the vincent j. coates chair in 13 neurobiology at salk. "to our surprise, we discovered thalamic input plays an essential role far earlier in brain development."
 
vision is relayed from the outside world into processing areas within the brain. the relay starts when light hits the retina, a thin strip of cells at the back of the eye that detects color and light levels and encodes the information as electrical and chemical signals. through retinal ganglion cells, those signals are then sent into the 14 geniculate 15 (lgn), a structure in thalamus.
 
in the next important step in the relay, the lgn routes the signals into the primary visual area (v1) in the neo-cortex, a multi-layered structure that is divided into 16 and anatomically distinct areas. v1 begins the process of extracting visual information, which is further carried out by "higher order" visual areas in the neo-cortex that are vitally important to visual perception. like parts in a machine, the functions of these areas are both individual and integrated. damage in one tiny area can lead to strange visual disorders in which a person may be able to see a moving ball, and yet not perceive it is in motion.
 
current dogma holds that this basic architecture is 17 genetically 18, with environmental input only playing a role later in development. one of the most famous examples of this idea is the nobel prize-winning work of visual neuroscientists david hubel and torsten wiesel, which showed that there is a "critical period" of sensitivity in vision. their finding was commonly interpreted as a warning that without exposure to basic visual 19 early in life, even an individual with a healthy brain will be unable to see correctly.
 
later discoveries in neural plasticity more optimistically suggested that early 20 can be overcome, and the brain can even 21 new neurons in specific areas. nevertheless, this still reinforced the idea that environmental influences might modify neural architecture, but only genetics could establish how cortical areas would be laid out.


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1 azlwe     
adj.知觉的,感觉的,知觉器官的
参考例句:
  • human powers of sensory discrimination are limited.人类感官分辨能力有限。
  • the sensory system may undergo long-term adaptation in alien environments.感觉系统对陌生的环境可能经过长时期才能适应。
2 bkzzzc     
adv.以前,先前(地)
参考例句:
  • the bicycle tyre blew out at a previously damaged point.自行车胎在以前损坏过的地方又爆开了。
  • let me digress for a moment and explain what had happened previously.让我岔开一会儿,解释原先发生了什么。
3 dnxzft     
adj.神经的,神经系统的
参考例句:
  • the neural network can preferably solve the non- linear problem.利用神经网络建模可以较好地解决非线性问题。
  • the information transmission in neural system depends on neurotransmitters.信息传递的神经途径有赖于神经递质。
4 6e49dcafe3638183c823d3aa5b12b010     
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》
5 01914f8eac35d7e14afa065217edd8c0     
n.基因( gene的名词复数 )
参考例句:
  • you have good genes from your parents, so you should live a long time. 你从父母那儿获得优良的基因,所以能够活得很长。 来自《简明英汉词典》
  • differences will help to reveal the functions of the genes. 它们间的差异将会帮助我们揭开基因多种功能。 来自英汉非文学 - 生命科学 - 生物技术的世纪
6 oudyb     
adj.脑的,大脑的;有智力的,理智型的
参考例句:
  • your left cerebral hemisphere controls the right-hand side of your body.你的左半脑控制身体的右半身。
  • he is a precise,methodical,cerebral man who carefully chooses his words.他是一个一丝不苟、有条理和理智的人,措辞谨慎。
7 5hmxa     
adj.为实用而设计的,具备功能的,起作用的
参考例句:
  • the telephone was out of order,but is functional now.电话刚才坏了,但现在可以用了。
  • the furniture is not fancy,just functional.这些家具不是摆着好看的,只是为了实用。
8 x6lxm     
n.输入(物);投入;vt.把(数据等)输入计算机
参考例句:
  • i will forever be grateful for his considerable input.我将永远感激他的大量投入。
  • all this information had to be input onto the computer.所有这些信息都必须输入计算机。
9 duhzy2     
adj.一心一意的;献身的;热诚的
参考例句:
  • he dedicated his life to the cause of education.他献身于教育事业。
  • his whole energies are dedicated to improve the design.他的全部精力都放在改进这项设计上了。
10 j2dxg     
n.陆标,划时代的事,地界标
参考例句:
  • the russian revolution represents a landmark in world history.俄国革命是世界历史上的一个里程碑。
  • the tower was once a landmark for ships.这座塔曾是船只的陆标。
11 lgixo     
adv.遗传上
参考例句:
  • all the bees in the colony are genetically related. 同一群体的蜜蜂都有亲缘关系。
  • genetically modified foods have already arrived on american dinner tables. 经基因改造加工过的食物已端上了美国人的餐桌。 来自英汉非文学 - 生命科学 - 基因与食物
12 wc4xq     
n.持有者,占有者;(台,架等)支持物
参考例句:
  • the holder of the office of chairman is reponsible for arranging meetings.担任主席职位的人负责安排会议。
  • that runner is the holder of the world record for the hundred-yard dash.那位运动员是一百码赛跑世界纪录的保持者。
13 me9xh     
adj.分子的;克分子的
参考例句:
  • the research will provide direct insight into molecular mechanisms.这项研究将使人能够直接地了解分子的机理。
  • for the pressure to become zero, molecular bombardment must cease.当压强趋近于零时,分子的碰撞就停止了。
14 83ey7     
adj.侧面的,旁边的
参考例句:
  • an airfoil that controls lateral motion.能够控制横向飞行的机翼。
  • mr.dawson walked into the court from a lateral door.道森先生从一个侧面的门走进法庭。
15 avsyg     
n.核,核心,原子核
参考例句:
  • these young people formed the nucleus of the club.这些年轻人成了俱乐部的核心。
  • these councils would form the nucleus of a future regime.这些委员会将成为一个未来政权的核心。
16 07b8a8a682798862ca0c3d3a567f4c3d     
adv.机能上地,官能地
参考例句:
  • objective to explore occlusion reconstruction by computer aided design (cad) with functionally-generated pathway (fgp). 目的探索借助功能性?记录(functionally-generated pathway,fgp)技术进行口腔固定修复体计算机辅助设计(computer aided design,cad)生理性建?的方法。 来自互联网
  • in this respect, the proceeding was functionally similar to a comparative licensing adjudication. 在这一点上,手续在作用上即类似于比较许可证发放的裁断。 来自英汉非文学 - 行政法
17 entirely     
ad.全部地,完整地;完全地,彻底地
参考例句:
  • the fire was entirely caused by their neglect of duty. 那场火灾完全是由于他们失职而引起的。
  • his life was entirely given up to the educational work. 他的一生统统献给了教育工作。
18 duszmp     
adj.坚定的;有决心的
参考例句:
  • i have determined on going to tibet after graduation.我已决定毕业后去西藏。
  • he determined to view the rooms behind the office.他决定查看一下办公室后面的房间。
19 lubwm     
n.刺激(物)
参考例句:
  • it is necessary to curtail or alter normally coexisting stimuli.必需消除或改变正常时并存的刺激。
  • my sweat glands also respond to emotional stimuli.我的汗腺对情绪刺激也能产生反应。
20 e9uy7     
n.匮乏;丧失;夺去,贫困
参考例句:
  • many studies make it clear that sleep deprivation is dangerous.多实验都证实了睡眠被剥夺是危险的。
  • missing the holiday was a great deprivation.错过假日是极大的损失。
21 itizy     
n.芽,萌芽;vt.使发芽,摘去芽;vi.长芽,抽条
参考例句:
  • when do deer first sprout horns?鹿在多大的时候开始长出角?
  • it takes about a week for the seeds to sprout.这些种子大约要一周后才会发芽。
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