Researchers have long known that the brain links kinds of new facts, related or not, when they are learned about the same time. Just as the taste of a cookie and tea can start a cascade1 of childhood memories, so a recalled bit of history homework can bring to mind a math problem.

    For the first time, scientists have recorded traces in the brain of that kind of contextual2 memory, the kaleidoscope3 of thoughts and emotions that surrounds every piece of newly learned information. The recordings, taken from the brains of people awaiting surgery for epilepsy4, suggest that new memories of even abstract facts are encoded5 in a brain-cell sequence that also contains information about what else was happening during and just before the memory was formed.

    The new study suggests that memory is like a streaming video6 that is bookmarked7, both consciously and subconsciously8, by facts, characters and thoughts. Experts cautioned that the new report falls short of1 revealing how contextual memory and different cues interact; some words might throw the mind into a vivid reverie2, while others do not.

    “It’s a demonstration of this very cool idea that you have remnants3 of previous thoughts still rattling around4 in your head, and you bind5 the representation of what’s happening now to the embers6 of those old thoughts,” said Ken Norman who did not participate in the study. “I think they have very good evidence that this process is crucial to recording your memories.”

    In the new study, doctors from the University of Pennsylvania and Vanderbilt University took recordings from tiny electrodes7 implanted8 in the brains of 69 people with severe epilepsy. The implants allow doctors to pinpoint9 the location of the flash10 floods11 of brain activity that cause epileptic12 seizures13.

    The patients performed a simple memory task. They watched a series of nouns appear on a computer screen, and after a brief distraction14 recalled as many of the words as they could, in any order. Repeated trials, with different lists of words, showed a predictable effect: The participants tended to remember the words in groups, beginning with one and recalling those that were just before or after.

    This pattern, which scientists call the contiguity15 effect16, is similar to what often happens in the card game concentration, in which players try to identify pairs in a grid17 of cards lying face-down. Pairs overturned close are often remembered together.

    Recording from the electrodes, the researchers looked for a neural18 pattern that had a very distinct signature19 — it updated continually. They found a strong signal in the temporal lobe20 of the brain. When participants recalled a word — “cat,” for example — the pattern in this region looked identical to when “cat” was originally seen on the computer screen.

[FS:PAGE]    “Here we have shown that the word before ‘cat’ has influenced the encoding for ‘cat,’ just as ‘cat’ has influenced the encoding of the next word,” said Michael J. Kahana, an author of the paper.

    The way the process works, the authors say, is something like reconstructing a night’s activities after a hangover1: remembering a fact (a broken table) recalls a scene (dancing), which in turn brings to mind more facts — like the other people who were there. Sure enough, the people in the study whose neural updating signals were strongest showed the most striking2 pattern of remembering words in groups.

    “When you activate one memory, you are reactivating a little bit of what was happening around the time the memory was formed,” Dr. Kahana said, “and this process is what gives you that feeling of time travel.” (593 words)

    1 cascade n. 大量涌現的東西;接踵而至的東西

    2 contextual adj. 根據上下文的;有來龍去脈的

    3 kaleidoscope n. 千變萬化;瞬息萬變。如：The bazaar was a kaleidoscope of strange sights and impressions.(集市的景象光怪陸離，紛然雜陳。)

    4 epileps y n. 癲癇;羊角風

    5 encode v. 編碼

    6 streaming video：流式視頻

    7 bookmark v. 保存;儲存

    8 subconsciously adv. 下意識地;潛意識地

    9 fall short of: 不符合;達不到(目標)

    10 reverie n. 幻想;空想;遐想

    11 remnants n.(常作復數)剩余的小部分;余下的數量

    12 rattling around: 在(大而空蕩蕩的)房屋里住或工作(該詞組在本文中引申為思想在腦中“縈繞”。)

    13 bind…to…：將……與……結合

    14 ember n.(通常作復數)余燼

    15 electrode n. 電極

    16 implant v. 在身體某部植入、 埋置、 嵌入(組織等);移植

    17 pinpoint v. 找出(某物)的確切位置

    18 flash adj. 突然的;突發的或迅速發生的

    19 floods of sth: 大批;大量

    20 epileptic adj. 癲癇的

    21 seizures n.(中風等的)發作

    22 distraction n. 思想不集中;分心;注意力分散的行為或狀態

    23 contiguity n. 接觸;相鄰;鄰近

    24 contiguity effect: 接近效應，需要相互間建立聯系的觀念，應該以空間和時間上接近的方式呈現。 例如，在多媒體呈現的材料中，對圖、表的文字說明，應該至于圖、表的附近。

    25 grid /grId/ n. 網格;(尤指)方格。如：a grid of tree-lined streets (樹木成行的棋盤式街道)

    26 neural adj. 神經的

    27 signature n. 識別標志;鮮明特征

    28 temporal lobe：顳葉，每側大腦半腦后下方位于枕葉的前方的腦葉，其中有大腦的聽覺中心。