人類自從進(jìn)化為人類后,，不僅有所得亦有所失,。我們的認(rèn)知能力比其它動(dòng)物的都高，我們可以有意識(shí)地去改變命運(yùn),。但另一方面,，我們高度進(jìn)化的大腦更易發(fā)生嚴(yán)重故障，比如神經(jīng)系統(tǒng)疾病和癡呆（dementia）,。最近,，一支神經(jīng)科學(xué)研究小組發(fā)現(xiàn)這些“的”和“失”都發(fā)生于同一特定的神經(jīng)回路（neural circuits）。
1999年,，有文章報(bào)道人類大腦和大猩猩的大腦都含有特異的被拉長(zhǎng)的神經(jīng)細(xì)胞——紡錘體神經(jīng)元（spindle neurons）,。這些細(xì)胞也被稱作Von Economo神經(jīng)元(VENs),位于大腦皮層中與社會(huì)行為、意識(shí)和情感有關(guān)的兩個(gè)部分,。在其它靈長(zhǎng)類動(dòng)物中沒有找到紡錘體神經(jīng)元,，近來有報(bào)道說在一些鯨中有出現(xiàn)（ScienceNOW， 27 November）,。
加州大學(xué)神經(jīng)生物學(xué)家William Seeley及其同事研究VENs對(duì)額顳癡呆(frontotemporal dementia,FTD)的影響,。額顳癡呆患者有時(shí)出現(xiàn)不適當(dāng)?shù)臎_動(dòng)行為甚至入店搶劫等犯罪行為。研究人員對(duì)比7例FTD死亡患者的大腦（實(shí)驗(yàn)組）和7例非腦部原因死亡的患者的大腦（對(duì)照組）,，以及5名被確診為阿爾茨海莫氏癥（另一種癡呆，主要是影響記憶）的患者,。研究人員發(fā)現(xiàn)包含VENs的兩個(gè)大腦區(qū)域中的一個(gè)——前扣帶皮層（anterior cingulate cortex）在FTD患者中出現(xiàn)了變化：與對(duì)照組相比,，VENs的數(shù)量縮減了74％。相反,，阿爾茨海莫氏癥患者的前扣帶皮層變化較小,，統(tǒng)計(jì)學(xué)意義上可以忽略。研究結(jié)果刊登于12月22日《Annals of Neurology》,。
Seeley及其同事認(rèn)為,，VENs在人類進(jìn)化出社會(huì)行為中扮演重要角色，但同時(shí)也將人類推向神經(jīng)變性疾病的危險(xiǎn)邊緣,。亞特蘭大Emory大學(xué)神經(jīng)科學(xué)家Lary Walker不贊誠(chéng)將復(fù)雜的社會(huì)行為歸因于特定細(xì)胞的行為和部分腦區(qū)域,。
英文原文：
'Social Dementia' Decimates Special Neurons
Being human has its pluses and minuses. Our cognitive powers are superior to that of other animals, and we can act consciously to alter our destinies. On the other hand, our highly evolved brains are prone to serious malfunctions such as mental illness and dementia. Now a team of neuroscientists has found that some of these blessings and curses might be linked to the same specialized neural circuits.
In 1999, researchers discovered that the brains of humans and great apes such as chimpanzees and gorillas contain special elongated nerve cells called spindle neurons. These cells, also known as Von Economo neurons (VENs), are localized in two parts of the cerebral cortex known to be associated with social behavior, consciousness, and emotion. They are not found in other primates, although very recently they were discovered in some whales (ScienceNOW, 27 November).
William Seeley, a neurologist at the University of California, San Francisco, and colleagues set out to see whether VENs play a role in a type of dementia that causes people to lose inhibition in social situations. People with frontotemporal dementia (FTD) engage in inappropriate and impulsive behavior and sometimes even carry out criminal acts such as shoplifting. The team looked at the brains of 7 deceased patients with FTD and compared them to 7 controls who had died of causes unrelated to the brain, as well as 5 patients diagnosed with Alzheimer's disease, a very different type of dementia that mainly affects memory. The researchers found that one of the two brain areas that contain VENs, the anterior cingulate cortex, looked very different in FTD patients: There was a 74% reduction in the number of VENs compared to controls. In contrast, Alzheimer's patients had only a small and statistically insignificant reduction, they report online today in Annals of Neurology.
Seeley and his colleagues conclude that VENs may play a key role in making humans the social creatures that we are, but that they also expose us to a higher risk of degenerative neural diseases. Lary Walker, a neuroscientist at Emory University in Atlanta, Georgia, says that the authors make a "reasonably compelling case that the VENs are selectively vulnerable in FTD". Nevertheless, Walker cautions against ascribing complex behaviors to the action of specific cells or regions in the brain.
