嬰兒自出生開(kāi)始的早期發(fā)育階段，會(huì)經(jīng)歷各種重要的轉(zhuǎn)變,。如嬰兒從偏好學(xué)習(xí)(preference learning)向厭惡性學(xué)習(xí)(aversion learning)轉(zhuǎn)變,。但這種轉(zhuǎn)變所包含的生物學(xué)機(jī)一直是神經(jīng)生物學(xué)家無(wú)法解釋的難題,。最近，紐約大學(xué)的神經(jīng)生物學(xué)家在9月27日Nature Neuroscience雜志上發(fā)表了一篇研究報(bào)告,，他們對(duì)剛出生大鼠的大腦功能的分子機(jī)制進(jìn)行探索,。
在該研究中，研究人員對(duì)大鼠大腦中一種神經(jīng)遞質(zhì)——多巴胺(dopamine)進(jìn)行研究，他們使幼鼠處于某種氣味中,，并同時(shí)提供一種消極的條件刺激——弱電擊(mild electric shock),。成年大鼠在這種弱電擊刺激下，皮質(zhì)酮(corticosterone)激素上升,，進(jìn)而導(dǎo)致大腦內(nèi)負(fù)責(zé)學(xué)習(xí)的杏仁核(amygdala)的神經(jīng)遞質(zhì)多巴胺的水平上升,。研究人員利用微陣列芯片（用于檢測(cè)多巴胺相關(guān)基因表達(dá)情況）和微透析技術(shù)（用于衡量多巴胺的水平），證實(shí)大腦內(nèi)多巴胺的水平與學(xué)習(xí)方式有關(guān),。
研究人員發(fā)現(xiàn)幼鼠在出生后第十天,，開(kāi)始從偏好學(xué)習(xí)向厭惡性學(xué)習(xí)轉(zhuǎn)變?；谏鲜銎べ|(zhì)酮和多巴胺之間的聯(lián)系,，研究人員成功的通過(guò)控制多巴胺來(lái)控制這種轉(zhuǎn)變發(fā)生的時(shí)間。研究人員給出生八天的幼鼠注射皮質(zhì)酮激素,，結(jié)果發(fā)現(xiàn)8天大的幼鼠的學(xué)習(xí)行為提前出現(xiàn)——幼鼠學(xué)會(huì)了回避與厭惡刺激(電刺激)相關(guān)的氣味,。而對(duì)照組的幼鼠未出現(xiàn)這種回避行為。研究人員給出生8天的幼鼠杏仁核直接注射多巴胺得到了相似的結(jié)果,。（生物谷Bioon.com）
相關(guān)研究：
PNAS：多巴胺調(diào)控的遺傳學(xué)習(xí)優(yōu)勢(shì)
Nature Neurosci.：大腦中情感和學(xué)習(xí)相關(guān)區(qū)域存在協(xié)同作用
NLM：松鼠皮質(zhì)醇水平影響其學(xué)習(xí)適應(yīng)能力
Neuron：首次證實(shí)大腦具潛意識(shí)學(xué)習(xí)能力
生物谷推薦原始出處：
Nature Neuroscience 12, 1367 - 1369 (2009)27 September 2009 | doi:10.1038/nn.2403
Transitions in infant learning are modulated by dopamine in the amygdala
Gordon A Barr1,2, Stephanie Moriceau3,4,5, Kiseko Shionoya3, Kyle Muzny3, Puhong Gao2, Shaoning Wang1,2 & Regina M Sullivan3,4,5
Behavioral transitions characterize development. Young infant rats paradoxically prefer odors that are paired with shock, but older pups learn aversions. This transition is amygdala and corticosterone dependent. Using microarrays and microdialysis, we found downregulated dopaminergic presynaptic function in the amygdala with preference learning. Corticosterone-injected 8-d-old pups and untreated 12-d-old pups learned aversions and had dopaminergic upregulation in the amygdala. Dopamine injection into the amygdala changed preferences to aversions, whereas dopamine antagonism reinstated preference learning.
1 Department of Anesthesiology and Critical Care Medicine, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA.
2 Department of Developmental Neuroscience, New York State Psychiatric Institute, New York, New York, USA.
3 Department of Zoology, University of Oklahoma, Norman, Oklahoma, USA.
4 Emotional Brain Institute, Nathan Kline Institute, Orangeburg, New York, USA.
5 Child and Adolescent Psychiatry, New York University Langone Medical Center, New York, New York, USA.
