生物谷：今天的人類已經(jīng)高度社會(huì)化，但是每次形成新的社會(huì)關(guān)系的時(shí)候,，人們都會(huì)在心里給對(duì)方的可信度打分。美國科學(xué)家7月27日在《美國自然人類學(xué)雜志》（American Journal of Physical Anthropology）網(wǎng)絡(luò)版上發(fā)表論文稱，這種行為是由大腦的類扁桃體結(jié)構(gòu)（amygdala）進(jìn)化重組造成的,。
科學(xué)家早已知道，大腦類扁桃體在感受恐懼方面起著關(guān)鍵作用,。最近研究又發(fā)現(xiàn),，孤獨(dú)癥患者的大腦類扁桃體含有更少的神經(jīng)細(xì)胞，特別是在外側(cè)核（lateral nucleus）區(qū)域,。
為了弄清不同靈長(zhǎng)類動(dòng)物大腦類扁桃體的差別,，在最新的研究中，美國加州大學(xué)圣地亞哥分校的人類學(xué)家Katerina Semendeferi領(lǐng)導(dǎo)研究小組測(cè)量了12具猿和人體標(biāo)本的大腦類扁桃體尺寸,，他們發(fā)現(xiàn),，人類大腦類扁桃體比猿的要大得多，并且人類大腦中外側(cè)核在類扁桃體中所占的比例也比猿的高,。研究人員表示,，雖然外側(cè)核的具體功能尚不清楚，但是它比類扁桃體其它區(qū)域與大腦顳葉（temporal lobe）有著更直接的聯(lián)系,，而大腦顳葉則與處理情緒和社交行為有關(guān),。
研究小組推測(cè)，自從人和猿在進(jìn)化路上“分道揚(yáng)鑣”后,，類扁桃體外側(cè)核便開始變大,，而這種變大可能正反映了生活在人類大族群里的社會(huì)壓力。
美國埃默里大學(xué)的人類學(xué)家James Rilling表示,，該項(xiàng)研究包括了大量的猿類標(biāo)本,，成果顯著。但是要想得到確切的結(jié)論,，即外側(cè)核與高度社會(huì)化有關(guān),，還需要做更多的研究。下一步的工作就是采用腦成像技術(shù)來確認(rèn)外側(cè)核與顳葉之間的聯(lián)系,。（科學(xué)網(wǎng) 梅進(jìn)/編譯）
原始出處:
Research Article
A comparative volumetric analysis of the amygdaloid complex and basolateral division in the human and ape brain
Nicole Barger 1, Lisa Stefanacci 2, Katerina Semendeferi 1 *
1Department of Anthropology, University of California, San Diego, La Jolla, CA 92023
2Salk Institute for Biological Studies, La Jolla, CA 92037
email: Katerina Semendeferi ([email protected])
*Correspondence to Katerina Semendeferi, Katerina Semendeferi, Department of Anthropology, University of California, San Diego, 9500 Gilman Drive, 0532, La Jolla, CA 92093-0532
Funded by:
Busch Gardens Zoo (Tampa Bay, FL)
Gladys Porter Zoo (Brownsville, TX)
Oregon Zoo (Portland, OR)
Henry Doorly Zoo (Omaha, NE)
Milwaukee County Zoo (Milwaukee, MI)
Yerkes National Primate Research Center (Atlanta, GA)
Chancellor's Interdisciplinary Collaboratory Scholarship
Kavli Institute for Brain and Mind at the University of California at San Diego
Keywords
brain evolution ?orangutan ?limbic ?comparative neuroanatomy ?morphometry
Abstract
The amygdaloid complex functions to facilitate effective appraisal of the social environment and is an essential component of the neural systems subserving social behavior. Despite its critical role in mediating social interaction, the amygdaloid complex has not attracted the same attention as the isocortex in most evolutionary analyses. We performed a comparative analysis of the amygdaloid complex in the hominoids to address the lack of comparative information available for this structure in the hominoid brain. We demarcated the amygdaloid complex and the three nuclei constituting its basolateral division, the lateral, basal, and accessory basal nuclei, in 12 histological series representing all six hominoid species. The volumes obtained for these areas were subjected to allometric analyses to determine whether any species deviated from expected values based on the other hominoids. Differences between groups were addressed using nonparametric comparisons of means. The human lateral nucleus was larger than predicted for an ape of human brain size and occupied the majority of the basolateral division, whereas the basal nucleus was the largest of the basolateral nuclei in all ape species. In orangutans the amygdala and basolateral division were smaller than in the African apes. While the gorilla had a smaller than predicted lateral nucleus, its basal and accessory basal nuclei were larger than predicted. These differences may reflect volumetric changes occurring in interconnected cortical areas, specifically the temporal lobe and orbitofrontal cortex, which also subserve social behavior and cognition, suggesting that this system may be acted upon in hominoid and hominid evolution. Am J Phys Anthropol, 2007. © 2007 Wiley-Liss, Inc.
