大腦中究竟是哪一部分負(fù)責(zé)將詞匯和事物聯(lián)系起來這樣復(fù)雜的概念學(xué)習(xí)過程呢？最近研究人員發(fā)現(xiàn)顳葉（temporal lobe）前緣部分負(fù)責(zé)概念學(xué)習(xí),。
曼徹斯特大學(xué)Matthew Lambon-Ralph 研究員在周三英國(guó)科學(xué)促進(jìn)協(xié)會(huì)(British Association for the Advancement of Science)年會(huì)上發(fā)表演講說：“人類關(guān)注大腦概念學(xué)習(xí)過程已經(jīng)有150年歷史了，我們相信能夠找到這種機(jī)制,。”
語義性失智（semantic dementia）是常見于65歲以下人群，緊次于阿爾茨海莫氏癥的第二大失智癥,。語義性失智患者語義性失智的患者會(huì)失去理解言語的意義或日常物品的名稱,，但是大腦的其它功能不受影響。他們可以做一些機(jī)械性的活動(dòng),，比如沏茶,，但是日復(fù)一日地做相同的動(dòng)作而不能將具體行為與精確的概念聯(lián)系起來。一名患者可以照著面前的照片準(zhǔn)確地畫出一只鴨子,，但是在起筆之前構(gòu)思的一分鐘里,，她職能勾畫出一只四肢腿的雞或者貓一類不準(zhǔn)確的草圖。Lambon-Ralph說：“他們可以識(shí)別一般圖像,，但是對(duì)具體細(xì)節(jié)不能認(rèn)知,。”
以前科學(xué)家潛意識(shí)里一直認(rèn)為大腦中負(fù)責(zé)處理概念問題的是遠(yuǎn)離顳葉的韋尼克氏區(qū)（Wernicke's area）但是對(duì)語義性失智患者大腦掃描發(fā)現(xiàn)，顳葉前緣可能更是關(guān)鍵部分,。
目前,，研究人員不僅對(duì)兩片顳葉之間的關(guān)系不甚了解，而且也不清楚是否大腦其它部分也參與概念學(xué)習(xí)過程,。只有這些關(guān)鍵問題都被解決了,，才有可能找出治療這些失智癥的治療措施。
英文原文：
Semantic memory pinpointed in the brain
The part of the brain responsible for the way we understand words, meanings and concepts has been revealed as the anterior temporal lobe – a region just in front of the ears.
In a novel experiment, neuroscientists pinpointed the exact region of the brain that is responsible for encoding semantic memory, which is disrupted in certain forms of dementia.
Semantic dementia is the second most common form of dementia in under-65s and is associated with significant loss of brain tissue in the temporal lobe. Patients are able to generate speech fluently but lose their knowledge of objects, people and abstract concepts.
Conceptual loss
For example, when shown a picture of a camel, they may understand that it is an animal but will not be able to give its name, and they lose the idea of associated concepts, such as deserts and palm trees.
Matthew Lambon-Ralph and colleagues at the University of Manchester in the UK used transcranial magnetic stimulation (TMS) on 12 healthy volunteers in an attempt to detect which area of the brain is responsible for encoding this type of memory.
In some positions, TMS caused the participants to experience a temporary version of the same type of memory loss seen in patients with semantic dementia, he found.
"Tired" neurons
TMS uses a figure-of-eight coil to send a magnetic pulse to stimulate and temporarily "tire out" neurons in specific areas of the brain. When TMS was performed over the temporal lobe, volunteers were unable to associate conceptual ideas to objects: and effect similar to semantic dementia. Within 5 to 10 minutes, brain function returned to normal.
The data allowed Lambon-Ralph and his team to locate semantic memory specifically to the frontal pole of the temporal lobe, an area just in front of the ear. “Conventional neurology thought this memory was associated with Wernick’s area, further back in the temporal lobe. Our new TMS data allows us to provide confirmation that the temporal pole gets involved in encoding a conceptual database,” says Lambon-Ralph.
The findings may one day help researchers treat dementia by targeting gene therapy or administering drugs directly into the brain region responsible for specific types of memory loss, says Clea Warburton, a neuroscientist at the University of Bristol, UK.
The research was announced at the British Association for the Advancement of Science Festival in Norwich, UK.
