2008年4月的愛思唯爾期刊《青春期健康雜志》（Journal of Adolescent Health）刊登了美國國立精神衛(wèi)生研究所的一項最新研究,。研究中采用核磁共振成像對青春期腦部的的變化做了描述,，同時研究了腦部的變化如何影響這個時期青少年認(rèn)知,，情感和行為,。
大腦是中樞神經(jīng)系統(tǒng)的最高級部分,，也是腦的主要部分,。它分為左右兩個半球,，二者由神經(jīng)纖維構(gòu)成的胼胝體相連,。被覆在大腦半球表面的灰質(zhì)叫大腦皮層。研究人員利用核磁共振成像技術(shù)對人類大腦進(jìn)行了掃描,，研究顯示大腦皮層的灰質(zhì)數(shù)量在十幾歲前會一直增長,，隨后會逐漸降低，直到晚年,。
研究人員發(fā)現(xiàn)青春期大腦有三個主要變化,。首先是信息綜合處理和連貫性上，腦部的功能性和結(jié)構(gòu)性增加變得更為一體化,。形象的比喻就是此時腦部功能不是認(rèn)識新的字母,，而是將已認(rèn)識的字母連成字，組成句,，最后成段,。接下來是大腦構(gòu)造的巨大變化，大腦總體積在3至15歲基本無變化,，某些區(qū)域的大腦物質(zhì)會一年內(nèi)增長近一倍,，但由于此后的清除無用細(xì)胞和大腦持續(xù)重組，大量的組織又迅速消失,。顳葉（語言處理和長時記憶）和頂葉（空間位置）在此時期也生長迅速,。大腦中發(fā)育最晚的是前額皮層，這部分負(fù)責(zé)計劃,、確定重點,、抑制沖動和權(quán)衡后果行為,，在青春期仍然處于成長階段。正因如此,，這個時期青少年行為上表現(xiàn)出易沖動,。
研究人員認(rèn)為，青春期的很多行為都與大腦結(jié)構(gòu)變化有著密切的關(guān)系,。
生物谷推薦原始出處：
Journal of Adolescent Health,，doi:10.1016/j.jadohealth.2008.01.007，Jay N. Giedd
The Teen Brain: Insights from Neuroimaging
Jay N. Giedd M.D., a,
Abstract
Few parents of a teenager are surprised to hear that the brain of a 16-year-old is different from the brain of an 8-year-old. Yet to pin down these differences in a rigorous scientific way has been elusive. Magnetic resonance imaging, with the capacity to provide exquisitely accurate quantifications of brain anatomy and physiology without the use of ionizing radiation, has launched a new era of adolescent neuroscience. Longitudinal studies of subjects from ages 3–30 years demonstrate a general pattern of childhood peaks of gray matter followed by adolescent declines, functional and structural increases in connectivity and integrative processing, and a changing balance between limbic/subcortical and frontal lobe functions, extending well into young adulthood. Although overinterpretation and premature application of neuroimaging findings for diagnostic purposes remains a risk, converging data from multiple imaging modalities is beginning to elucidate the implications of these brain changes on cognition, emotion, and behavior.
