健忘癥患者總是在拼命回憶自己的過去,。然而根據(jù)一項(xiàng)新的研究,，他們可能還在費(fèi)力地設(shè)想自己的未來,。研究人員發(fā)現(xiàn),，因海馬狀突起（海馬區(qū)）——與記憶密切相關(guān)的大腦區(qū)域——受損而患上記憶缺失的病人,，很難想象新的經(jīng)歷,。
在這項(xiàng)研究中,，英國(guó)倫敦大學(xué)學(xué)院的認(rèn)知神經(jīng)學(xué)家Eleanor Maguire和同事對(duì)5名健忘癥患者進(jìn)行了監(jiān)測(cè)。所有這些患者都是由于大腦海馬狀突起受損而導(dǎo)致嚴(yán)重的記憶障礙——他們很難形成新的記憶,，并且無法記住大腦受傷后發(fā)生的事情,。有10名與這些健忘癥患者的年齡和受教育水平相仿的正常人作為對(duì)照組參與了此項(xiàng)研究。這項(xiàng)研究成果發(fā)表于本周的美國(guó)《國(guó)家科學(xué)院院刊》網(wǎng)絡(luò)版上,。
Maguire的研究小組要求每一名受試者想象并描述他們?cè)谖磥碛锌赡苡龅降膸讉€(gè)普通場(chǎng)景,，例如碰見一個(gè)朋友或是去海濱游玩、去酒吧喝酒,、去超市購物,。健康的受試者均給出了豐富的描述，例如他們談到海岸的曲線,、海浪拍打岸邊的聲音以及腳踩炙熱沙灘的感覺,。而健忘癥患者雖然能夠按照研究人員的意圖去做，但他們的描述卻要生澀得多,。與健康的志愿者相比,，健忘癥患者只提及了較少的事物和感覺細(xì)節(jié)，例如聲音和氣味,，以及較少的因想象的場(chǎng)景而產(chǎn)生的想法和情緒,。通過健忘癥患者完成的一份調(diào)查問卷，研究人員發(fā)現(xiàn),，他們所想象的都是一些景象的碎片而非一幅完成的畫面,。
美國(guó)圖森市亞利桑那大學(xué)的認(rèn)知神經(jīng)學(xué)家Lynn Nadel表示，這一發(fā)現(xiàn)對(duì)傳統(tǒng)的教科書形成了挑戰(zhàn),，前者將海馬狀突起的主要功能描述為編碼新的記憶,。Nadel指出：“這項(xiàng)研究成果表明，我們能夠利用相同的系統(tǒng)回憶過去并構(gòu)建可能的未來,。”加拿大多倫多大學(xué)的認(rèn)知神經(jīng)學(xué)家Morris Moscovitch表示,，Maguire的工作同時(shí)也印證了其他科學(xué)家最近取得的研究成果——海馬狀突起能夠?qū)⒁恍﹫?chǎng)景的要素結(jié)合在一起，從而在腦海中形成一幅連貫的畫面,。Moscovitch指出：“如果想要生動(dòng)地構(gòu)建過去,、未來或者想象的事物，那你絕對(duì)離不開海馬狀突起,。”
英文原文：
Stuck in the Present
People with amnesia struggle to remember their past. They may also struggle to envision their future, according to a new study. Researchers have found that people with amnesia caused by damage to the hippocampus, a brain region intimately tied to memory, have difficulty imagining new experiences.
In the new study, published online this week by the Proceedings of the National Academy of Sciences, cognitive neuroscientist Eleanor Maguire at University College London and colleagues examined five amnesic patients. All of them had severe memory deficits caused by damage to the hippocampus; they had great difficulty forming new memories and recalling events that occurred after their injuries. Ten healthy individuals who matched the patients' ages and education levels participated in the study as controls.
Maguire's team asked each subject to imagine and describe several commonplace scenarios they might reasonably expect to encounter in the future, such as meeting a friend or visiting a beach, a pub, or a market. The healthy subjects provided rich descriptions, remarking for example on the curve of a beach, the sound of waves hitting the shore, and the feel of burning hot sand. The amnesic patients were able to follow the researchers' instructions, but their descriptions were far less vivid. Compared to healthy subjects, the patients described fewer objects, fewer sensory details such as sounds and smells, and fewer thoughts or emotions that might be evoked in the imagined scenario. The patients' responses on a questionnaire indicated that what they saw in their mind's eye were fragmented collections of images rather than coherent scenes.
The findings challenge the traditional textbook view that the main job of the hippocampus is to encode new memories, says Lynn Nadel, a cognitive neuroscientist at the University of Arizona in Tucson. "The claim here is that the same system we use to remember the past we also use to construct possible futures," he says. Maguire's study fits with other recent work suggesting that the hippocampus binds together the elements of a scene to create a coherent mental picture, says Morris Moscovitch, a cognitive neuroscientist at the University of Toronto in Canada. "In order to have vivid constructions of the past, the future, or of imaginary events, you always need the hippocampus," he says.
