大脑中究竟是哪一部分负责将词汇和事物联系起来这样复杂的概念学习过程呢？最近研究人员发现颞叶（temporal lobe）前缘部分负责概念学习。
曼彻斯特大学Matthew Lambon-Ralph 研究员在周三英国科学促进协会(British Association for the Advancement of Science)年会上发表演讲说：“人类关注大脑概念学习过程已经有150年历史了，我们相信能够找到这种机制。”
语义性失智（semantic dementia）是常见于65岁以下人群，紧次于阿尔茨海莫氏症的第二大失智症。语义性失智患者语义性失智的患者会失去理解言语的意义或日常物品的名称，但是大脑的其它功能不受影响。他们可以做一些机械性的活动，比如沏茶，但是日复一日地做相同的动作而不能将具体行为与精确的概念联系起来。一名患者可以照着面前的照片准确地画出一只鸭子，但是在起笔之前构思的一分钟里，她职能勾画出一只四肢腿的鸡或者猫一类不准确的草图。Lambon-Ralph说：“他们可以识别一般图像，但是对具体细节不能认知。”
以前科学家潜意识里一直认为大脑中负责处理概念问题的是远离颞叶的韦尼克氏区（Wernicke's area）但是对语义性失智患者大脑扫描发现，颞叶前缘可能更是关键部分。
目前，研究人员不仅对两片颞叶之间的关系不甚了解，而且也不清楚是否大脑其它部分也参与概念学习过程。只有这些关键问题都被解决了，才有可能找出治疗这些失智症的治疗措施。
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.
