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细节必须被整合，事后才能回想起来。

加州大学欧文分校的研究者们发现，一个人能回想起一件事细节的多少取决于是否大脑中某些部分被激活，将记忆进行“打包”。
这项研究可能有助于解释为什么发生撞车事故时，有时人们仅能想起片段，而有时却能想起每一个活生生的细节。

该试验中应用了功能性核磁成像技术（fMRI），这样科学家们可以观察到当受试者经历一件复杂连续细节事件时他们大脑内发生的变化。他们发现，能想起经历事件的每个方面、每个细节的受试者，调用了大脑中一个可以在事发同时将事件每个不同细节整合、打包的特殊区域。当这个区域未被激活来整合打包细节时，则只能回想起一些事情的片段。这一发现发表在最新一期的《神经元》杂志上。

欧文分校学习与记忆神经生物学中心主任，论文第一作者，Michael Rugg说：“这项研究为心理学家们一直所告诉我们的事实提供了神经学基础。你不能提取出你未曾储存过的记忆；如果你当时没有注意，后来就不可能回想起来。”

科学家们向23个受试者展示了一系列单词并同时进行功能性核磁成像技术（fMRI）扫描。这些单词有不同的颜色，它们可能出现在屏幕上四格表中的任意一格。然后受试者须判定单词是否有动画效果。一段时间后，这些单词再次向受试者展示，掺合一些以前没有见过的单词。再问他们以前是否见过那些单词，并判断单词的颜色及在四格表中的位置。

假如受试者后来能记住单词的颜色，那么他记忆时大脑内一个特殊的颜色处理相关区域就会特别兴奋；假如受试者后来可以记住单词的位置，空间处理相关区域就产生兴奋；如果受试者可以同时记住单词、颜色以及位置，兴奋就会出现在大脑的另一个重要区域。研究者观察到，大脑皮层顶叶顶内沟活动增强。这个区域可能负责将一个特定记忆的所有特征进行整合，这样连续的和一些更重要细节（如单词的判定）才能被回忆起来。

该研究的主要作者，研究生Melina Uncapher说：“我们知道，假如顶内沟受到损伤，那么一个人就不能顾全同一物体的多个方面，如它的大小、颜色。这项研究为这个区域对记忆中记忆成份在大脑中进行整合的重要性提供了证据。记忆不是各部分之和。对一件事的完整的记忆要求在它贮存前，这件事的特征在大脑整合、处理，形成一个总的表象。”

这项研究由国立精神卫生研究所和威康基金会赞助，伦敦大学Leun Otten教授参与合作。 

Memories: It's all in the packaging, scientists say

Details must be integrated when event occurs to be remembered later

Irvine, Calif., November 9, 2006
Researchers at UC Irvine have found that how much detail one remembers of an event depends on whether a certain portion of the brain is activated to “package” the memory.

The research may help to explain why sometimes people only recall parts of an experience such as a car accident, and yet vividly recall all of the details of a similar experience.

In experiments using functional magnetic resonance imaging (fMRI), the scientists were able to view what happened in the brains of subjects when they experienced an event made up of multiple contextual details. They found that participants who later remembered all aspects of the experience, including the details, used a particular part of the brain that bound the different details together as a package at the time the event occurred. When this brain region wasn’t activated to bind together the details, only some aspects of an event were recalled. The findings appear in the current issue of Neuron.

“This study provides a neurological basis for what psychologists have been telling us for years,” said Michael Rugg, director of UCI’s Center for the Neurobiology of Learning and Memory and senior author of the paper. “You can’t get out of memory what you didn’t put into it. It is not possible to remember things later if you didn’t pay attention to them in the first place.”

The scientists presented 23 research subjects with a list of words while they underwent an fMRI scan. The words were in different colors and would appear in one of four quadrants on a screen. The subjects had to decide whether the words represented an animate or inanimate object. Later, the participants were presented the words again, interspersed with words they had not seen before, and asked if they remembered seeing those words before. They were also asked if they remembered in what color the word had originally been and in which of the four quadrants it had originally appeared.

If the participant could later remember the color of the word, a particular area of the brain associated with color processing was especially active during learning. If the subject later remembered the location of the word, activity was seen in an area associated with spatial processing. But if the subject remembered the word, the color and the location, then another critical brain region became involved. The researchers observed enhanced activity in the intra-parietal sulcus, a part of the parietal cortex. It appears that this region is responsible for binding together all the features of a particular memory so that contextual details, as well as more central aspects of the event such as the identity of the word, can later be recalled.

“We know that if the intra-parietal sulcus is damaged, then someone cannot attend to multiple aspects of the same object, such as its size and color,” said Melina Uncapher, a graduate student researcher and lead author of the study. “This study provides empirical evidence for how critical this region is for bringing the constituents of a memory together in the brain.

“Memory is more than a sum of its parts. A complete memory of an event requires that the features of the event be brought together and processed by the brain as a common perceptual representation, before being stored.”

Leun Otten of University College London collaborated on the study. The research was funded by the National Institute of Mental Health and the Wellcome Trust.

http://www.today.uci.edu/news/release_detail.asp?key=1539

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