托福聽(tīng)力考試經(jīng)常出現(xiàn)加試題，通常這樣的情況下考試時(shí)間會(huì)延長(zhǎng)。雖然說(shuō)加試成績(jī)不計(jì)入總分，但是大家還是會(huì)很緊張，因?yàn)楫吘刮覀儾恢滥男┦羌釉囶}。如果可以事前知道哪些是加試題，我們就不用那么緊張了。
神經(jīng)元細(xì)胞
lecture神經(jīng)膠質(zhì)細(xì)胞研究。教授說(shuō)早期對(duì)人類(lèi)大腦的研究集中在神經(jīng)細(xì)胞neuron，讓一男生起來(lái)回答上節(jié)課的主要內(nèi)容，男生說(shuō)生物電生物電 bioelectricity 通過(guò)神經(jīng)細(xì)胞傳導(dǎo)，通過(guò)兩個(gè)神經(jīng)細(xì)胞的接觸點(diǎn)傳到下一個(gè)細(xì)胞，有趣的是。。說(shuō)到這里被教授打斷，說(shuō)他答得已經(jīng)很完整了(有題，問(wèn)教授打斷他的用意)。神經(jīng)膠質(zhì)細(xì)胞glial cells的作用在早期被忽視了，人們認(rèn)為膠質(zhì)細(xì)胞只有支持神經(jīng)細(xì)胞的作用。后來(lái)人們發(fā)現(xiàn)膠質(zhì)細(xì)胞也有傳導(dǎo)信息的作用，不是通過(guò)生物電，而是化學(xué)物質(zhì)傳導(dǎo)。于是總共有三種傳導(dǎo)方式，神經(jīng)細(xì)胞間，膠質(zhì)細(xì)胞間，神經(jīng)和膠質(zhì)細(xì)胞互相傳導(dǎo)。而且發(fā)現(xiàn)膠質(zhì)細(xì)胞的數(shù)量及其巨大，遠(yuǎn)多于神經(jīng)細(xì)胞。同時(shí)還可能有修復(fù)神經(jīng)細(xì)胞，決定哪些神經(jīng)長(zhǎng)的大[記得可能不準(zhǔn)]。教授又說(shuō)，膠質(zhì)細(xì)胞可能與智力有關(guān)，越多智商越高，但這不確定。教授說(shuō)對(duì)膠質(zhì)細(xì)胞的研究是一個(gè)很open up的領(lǐng)域，建議學(xué)生們可以考慮畢業(yè)后作深入研究(有題)。
重要：biology 講glial cell。以往人們對(duì)神經(jīng)傳導(dǎo)的研究?jī)H限于neuron(神經(jīng)元)，也叫nervecell。神經(jīng)傳導(dǎo)通過(guò)electrical communication從一個(gè)結(jié)點(diǎn)傳到另一個(gè)結(jié)點(diǎn)，神經(jīng)元被認(rèn)為起主要作用，glial cell研究的很少，一直被忽略，被看作help the growth of neurons
(出題)，起輔助作用。后來(lái)偶然發(fā)現(xiàn)大腦中g(shù)lial cell比neuron的數(shù)目多很多，glial cell引起了科學(xué)家的重視，開(kāi)始研究它究竟起什么作用(此處出題，問(wèn)glialcell怎么引起科學(xué)家注意的)。后來(lái)有一重大突破，
發(fā)現(xiàn)glial cell傳導(dǎo)信號(hào)不是用的electricalsignal，而是用chemical conductor(一說(shuō)chemical communication)(此處出題)。傳統(tǒng)觀點(diǎn)一直誤以為glial cell也像nervecell一樣用電信號(hào)。后來(lái)談到glial cell可能的作用：使人更intelligent。對(duì)glial cell的認(rèn)識(shí)目前十分有限，但相關(guān)研究已經(jīng)開(kāi)始流行，是大家畢業(yè)之后可選的研究課題(此處出題)
Glial cell isthought to help the growth of neurons. However, scientists accidentallydiscover that glial’s amount is much more than the neuron. So glial attractpeople’s attention. They use chemical conductor to communicate with others. Soglial to neuron, g to n, g to g, n to n are all available. In the past glialwas thought to support nerve cell.
Glial cells (神經(jīng)膠質(zhì)細(xì)胞)and Neurons (神經(jīng)細(xì)胞)
Glial cells,commonly called neuroglia or simply glia, are non-neuronal cellsthat provide support and nutrition, maintainhomeostasis,form myelin,and participate in signal transmission in the nervoussystem. In the human brain, glia are estimated to outnumberneurons by about 10 to 1.[1]
Glial cellsprovide support and protection for neurons, the other main type of cell in the central nervoussystem. They are thus known as the "glue"膠水 of the nervous system. The four main functions ofglial cells are to surround neurons and hold them in place固定, to supply nutrientsand oxygento neurons供養(yǎng), to insulate one neuron from another隔開(kāi), and to destroypathogensand remove dead neurons破壞病菌，轉(zhuǎn)移死N.
Glia wasdiscovered in 1856by the pathologist Rudolf Virchow in his search for a 'connectivetissue' in the brain大腦的連接組織.The human brain contains about ten timesmore glial cells than neurons. [1]Following its discovery in the late 19th century, this fact underwentsignificant media distortion, emerging as the famous myth claiming that"we are using only 10% of our brain". The role of glial cells asmanagers of communications in the synapse突觸 gap,thus modifying learning pace, has been discovered only very recently
In addition toneurons, the nervous system is populated with another category of cells, glialcells. Glial cells are approximately 10 times more plentiful than neurons, butsince they are approximately one-tenth the size, they take up equal size, gliais a Greek term meaning glue, researches originally believed that glial cellsserved as the putty that held the neurons together, recent research indicatesthat these cells provide very important contributions.
a neuron is thefunctioning unit of the nervous system, specialized to receive, integrate, andtransmit information, the flow of information moves in the following direction.
托福聽(tīng)力加試題的位置不固定，考生很難分辨哪一道是加試題，只能通過(guò)日常積累來(lái)判斷。大家盡量不要憑空揣測(cè)，以免影響自己的托福成績(jī)。