如果你是一個(gè)老年嬰兒潮，你或許已經(jīng)注意到自己在某些方面的困難,，比如開(kāi)車(chē)到陌生的地點(diǎn)或在超市挑選新品牌的橄欖油,，你可以認(rèn)為你大腦中的腦白質(zhì)負(fù)主要責(zé)任。
一項(xiàng)有關(guān)大腦圖譜的最新研究發(fā)表在4月11日的Journal of Neuroscience雜志上,，研究人員發(fā)現(xiàn)人在新的環(huán)境下做決定的能力,，隨著年齡的增長(zhǎng)而減弱，并其這一減弱與連接大腦皮層中稱(chēng)為內(nèi)側(cè)前額葉皮質(zhì)區(qū)域與大腦深處其他兩塊區(qū)域的兩條特定的白質(zhì)通路的完整性有關(guān),。
灰質(zhì)是大腦的一部分,，腦、脊髓內(nèi)神經(jīng)元集中的地方,，色澤灰暗,，所以稱(chēng)為灰質(zhì)?；屹|(zhì)內(nèi)功能相同的神經(jīng)細(xì)胞體集合一起稱(chēng)為神經(jīng)核,。在過(guò)去，大多數(shù)腦成像的研究集中于灰質(zhì),。然而最近,，神經(jīng)學(xué)家已經(jīng)開(kāi)始更多關(guān)注白質(zhì)研究。白質(zhì)鏈接與大腦的處理速度和注意力等有關(guān),，這項(xiàng)研究是首次探討了學(xué)習(xí)和決策與腦白質(zhì)之間的聯(lián)系,。
大腦掃描圖
影像科學(xué)范德比爾特的心理學(xué)系和研究所博士后研究員Gregory R. Samanez-Larkin說(shuō)：決策能力的下降與白質(zhì)的完整性的證據(jù)表明，有可能將來(lái)會(huì)有有效的方式介入這一過(guò)程,。一些研究表明白質(zhì)的連接可以通過(guò)加強(qiáng)認(rèn)知訓(xùn)練等具體形式來(lái)提高,。
這項(xiàng)研究涉及了25名從21到85歲不等的成年人。他們被要求完成貨幣政策的學(xué)習(xí)任務(wù),，任務(wù)的目的是引發(fā)這些人心理學(xué)家所說(shuō)的概率性獎(jiǎng)勵(lì)學(xué)習(xí),。Samanez-Larkin說(shuō)：根據(jù)以往的經(jīng)驗(yàn)和結(jié)果的不確定性，每當(dāng)我們嘗試選擇最佳替代決定是,，我們都是靠概率性獎(jiǎng)勵(lì)性學(xué)習(xí)來(lái)實(shí)現(xiàn)的,。
在同一天，研究人員利用磁共振成像技術(shù)對(duì)參與者的大腦進(jìn)行掃描,。實(shí)驗(yàn)發(fā)現(xiàn)丘腦中關(guān)鍵性白質(zhì)連接存在于與決策有關(guān)的大腦區(qū)域（內(nèi)側(cè)前額葉皮質(zhì)）,、與情緒和動(dòng)機(jī)方面有關(guān)的內(nèi)側(cè)前額葉皮層腹側(cè)紋狀體,。（生物谷：Bioon.com）
doi:10.1523/JNEUROSCI.5756-11.2012
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PMID:
Frontostriatal White Matter Integrity Mediates Adult Age Differences in Probabilistic Reward Learning
Gregory R. Samanez-Larkin, Sara M. Levens, Lee M. Perry, Robert F. Dougherty, and Brian Knutson
Frontostriatal circuits have been implicated in reward learning, and emerging findings suggest that frontal white matter structural integrity and probabilistic reward learning are reduced in older age. This cross-sectional study examined whether age differences in frontostriatal white matter integrity could account for age differences in reward learning in a community life span sample of human adults. By combining diffusion tensor imaging with a probabilistic reward learning task, we found that older age was associated with decreased reward learning and decreased white matter integrity in specific pathways running from the thalamus to the medial prefrontal cortex and from the medial prefrontal cortex to the ventral striatum. Further, white matter integrity in these thalamocorticostriatal paths could statistically account for age differences in learning. These findings suggest that the integrity of frontostriatal white matter pathways critically supports reward learning. The findings also raise the possibility that interventions that bolster frontostriatal integrity might improve reward learning and decision making.
