amanda liu :: 痞客邦 ::

Oct 29 Mon 2012 09:36
如何遺忘？

如何遺忘？當大腦受傷後造成記憶力變差時，人們通常認為這是腦中資訊喪失或資訊變得無法獲取的後果。但是現在，研究人員給出了一種替代性的解釋：並不是腦受傷患者在觀看熟悉物件時會將其當作新的物件，他們可能將新的物件看作是熟悉的物件，從而為他們自己製造了一種“虛假的記憶”。Stephanie McTighe及其同事在大鼠中做了一個試驗，在該實驗中，他們單獨地（而非同時地）給這些大鼠展示了一個熟悉的物件及一個新的物件（這是在大多數從前的記憶測試中所做的實驗），他們對健康及腦損傷大鼠是如何對待這兩種物件的進行了觀察。在正常情況下，健康大鼠會對熟悉的物件花較少的探索時間（證明其有某些記憶力），而對新物件花較多的探索時間。然而，這些研究人員說，那些大腦受傷的大鼠似乎將它們熟悉的及陌生的物件認作是相同的東西。當研究人員在這些大鼠探索這些物件之前和之後將這些大鼠放置在一個黑暗無光的環境之中（以此來帛琉限制對它們的視覺刺激），McTighe及其團隊注意到，大腦受傷的大鼠不再會將熟悉的物件與新的物件混淆起來。這一發現表明，持續性的視覺刺激（每當我們睜開眼睛的時候它們就會對我們進行大肆轟擊）具有影響我們腦中的還沒有充分發展成或固定下來的片斷記憶的能力。將這些結果與那些先前的研究相結合，McTighe和她的同事提示，腦中的特定區域會通過它們的專門的資訊處理功能來形成整體的記憶。他們不贊成腦中的某個特別的區域是作為專門的記憶系統的這一概念。在Howard Eichenbaum所撰寫的觀點欄目中，他將這些結果放在了一個範圍更廣的背景之中，他討論了它們是如何與我們對大腦處理記憶的不斷變化的理解相適應的。 Hierarchical View(The representational-hierarchical view.)How do we forget things?When brain damage results in poor memory it is usually considered to be a consequence of information in the brain 花蓮民宿being lost or rendered inaccessible. Now, however, researchers are offering an alternative explanation: Instead of viewing familiar objects as novel, brain damaged patients might be viewing novel objects as familiar, creating a kind of "false memory" for themselves. Stephanie McTighe and colleagues performed an experiment with rats in which they presented the rodents with a familiar object and a novel object separately—instead of simultaneously, which most previous tests of memory have done—and they observed how both healthy and brain-damaged rats treated those two objects. Normally, healthy rats spend less time investigating the familiar object, demonstrating some kind of remembrance, and more time investigating the novel object. However, these researchers seosay that their brain-damaged rats seemed to recognize both the familiar and the novel objects as if they were the same. When the researchers placed the rats in a dark, sightless environment (thereby limiting their visual stimuli) before and after the rodents investigated the objects, McTighe and her team noticed that the brain-damaged rats no longer confused familiar objects with novel ones. This finding implies that constant visual stimuli, which bombards us every time we open our eyes, has the power to influence fragmented memories in our brains that may not have fully developed or taken hold yet. Combining these results with those of previous studies, McTighe and her colleagues suggest that specific areas of the brain contribute to memory as a whole through 租房子their specialized information-processing functions. They argue against the notion of a particular region of the brain that acts as a dedicated memory system. A Perspective by Howard Eichenbaum places these results in a wider context, discussing how they fit into our changing understanding of how the brain processes memory. Why Do We Forget Things?The brain can store a vast number of memories, so why can't we find these memories when we need to? A new study provides insights into this question. Our brains are crammed with a massive amount of memories that we have formed over a lifetime of experiences. These memories range from the profound (who am I and how did I get here?) to the most trivial (the license plate of the car at a stoplight). Furthermore, our 借貸memories also vary considerably in their precision. Parents, for instance, often know the perils of a fuzzy memory when shopping for a birthday gift for their child: remembering that their son wanted the G.I. Joe with Kung Fu Grip rather than the regular G.I. Joe could make an enormous difference in how well the gift is received. Thus, the “fuzziness” of our memory can often be just as important in our daily lives as being able to remember lots and lots of information in the first place. Different Levels of Detail for Different Types of Memory?In the past several decades, cognitive psychologists have determined that there are two primary memory systems in the human mind: a short-term, or “working,” memory that temporarily holds information about just a few 住商房屋things that we are currently thinking about; and a long-lasting memory that can hold massive amounts of information gained through a lifetime of thoughts and experiences. These two memory systems are also thought to differ in the level of detail they provide: working memory provides sharp detail about the few things we are presently thinking about, whereas long-term memory provides a much fuzzier picture about lots of different things we have seen or experienced. That is, although we can hold lots of things in long-term memory, the details of the memory aren’t always crystal-clear and are often limited to just the gist of what we saw or what happened.A recently published study by Timothy F. Brady, a cognitive neuroscientist at the Massachusetts Institute of 新成屋Technology, and colleagues suggests that these long-term memories may not be nearly as fuzzy as once thought, however. In their work, the researchers asked subjects to try to remember 3,000 pictures of common objects—including items such as backpacks, remote controls and toasters—that were presented one at a time for just a few seconds each. At the end of this viewing phase, the researchers tested subjects’ memory for each object by showing them two objects and asking which one they had seen before. Not surprisingly, subjects were exceptionally good (more than 90 percent correct) even though there were thousands of objects to remember. This high success rate attests to the massive storage ability of long-term memory. What was most surprising, however, was the 結婚西裝amazing level of detail that the subjects had for all of these memories. The subjects were just as good at telling the difference between two pictures of the same object even when the objects differed in an extremely subtle manner, such as a pair of toasters with slightly different slices of bread.If It’s Not Fuzzy, Why Do We Still Forget Things?This new work provides compelling evidence that the enormous amount of information we hold in long-term memory is not so uncertain after all. It seems that we actually hold representations of things we’ve seen in a fairly detailed and precise form.Of course, this finding raises the obvious question: if our memories aren’t all that fuzzy, then why do we often forget the details of things we want to remember? One 房屋出租explanation is that, although the brain contains detailed representations of lots of different events and objects, we can’t always find that information when we want it. As this study reveals, if we’re shown an object, we can often be very accurate and precise at being able to say whether we’ve seen it before. If we’re in a toy store and trying to remember what it was that our son wanted for his birthday, however, we need to be able to voluntarily search our memory for the right answer—without being prompted by a visual reminder. It seems that it is this voluntary searching mechanism that’s prone to interference and forgetfulness. At least that’s our story when we come home without the Kung Fu Grip G.I. Joe. 九份民宿Souece:http://www.scientificamerican.com/article.cfm?id=why-do-we-forget-things

rf62zzahbx 發表在痞客邦留言(0) 人氣()

amanda liu

目前分類：未分類文章 (133)

站方公告

活動快報

我的好友

熱門文章

文章分類

最新文章

最新留言

動態訂閱

文章精選

文章搜尋

新聞交換(RSS)

誰來我家

參觀人氣

QR Code

POWERED BY