功能核磁共振大腦掃描顯示圖
據(jù)物理學(xué)家組織網(wǎng)報(bào)道,，加拿大不列顛哥倫比亞大學(xué)一項(xiàng)最新研究結(jié)果發(fā)現(xiàn),，人在走神時(shí)大腦的活動(dòng)反而比科學(xué)家以前想象的更為活躍。
這項(xiàng)研究發(fā)現(xiàn),，當(dāng)我們心不在焉的時(shí)候,，大腦很多區(qū)域的活動(dòng)都有所增強(qiáng)。研究結(jié)果刊登在最新一期美國(guó)《國(guó)家科學(xué)院院刊》（PNAS）上,。事實(shí)上,，該研究表明，一些同解決復(fù)雜問題有關(guān)的大腦區(qū)域在我們進(jìn)行天馬行空的想象時(shí)高度活躍,，而科學(xué)家之前認(rèn)為這些區(qū)域在我們走神時(shí)處于休眠狀態(tài),。
領(lǐng)導(dǎo)實(shí)施這項(xiàng)研究的不列顛哥倫比亞大學(xué)心理學(xué)教授卡琳娜·克里斯托夫（Kalina Christoff）表示：“思緒飄揚(yáng)一般同懶散或精力不集中等負(fù)面事情有關(guān),。但是，這項(xiàng)研究卻表明我們走神時(shí)大腦活動(dòng)反而更為活躍,，活躍程度甚至超過我們專心從事一些日常工作的時(shí)候,。”
在研究中，志愿者躺在fMRI掃描儀里面,，當(dāng)數(shù)字出現(xiàn)在屏幕上時(shí)進(jìn)行按鍵等簡(jiǎn)單活動(dòng),。研究人員可以通過大腦掃描、志愿者的主動(dòng)報(bào)告以及追蹤志愿者的成績(jī)來調(diào)查他們的瞬間注意力,。研究結(jié)果發(fā)現(xiàn),，走神(最多可以占據(jù)我們清醒狀態(tài)下三分之一的時(shí)間)是一種重要的認(rèn)知狀態(tài)，在這種狀態(tài)下,，我們可能在不知不覺中將注意力從當(dāng)前的工作轉(zhuǎn)向梳理日常生活中的重要問題,。
在此之前，科學(xué)家認(rèn)為大腦的“默認(rèn)網(wǎng)絡(luò)”是走神時(shí)大腦中唯一活躍的區(qū)域,。大腦“默認(rèn)網(wǎng)絡(luò)”同日常輕松的智力活動(dòng)有關(guān)，包括內(nèi)側(cè)前額葉皮質(zhì),、后扣帶回皮質(zhì)和顳頂聯(lián)合區(qū)(temporoparietal junction),。但是，這項(xiàng)研究卻發(fā)現(xiàn),，大腦的“執(zhí)行網(wǎng)絡(luò)”在我們走神時(shí)也會(huì)被激活,。大腦“執(zhí)行網(wǎng)絡(luò)”負(fù)責(zé)解決高度復(fù)雜的問題，由側(cè)面前額葉皮質(zhì)和背面后扣帶回皮質(zhì)構(gòu)成,。
克里斯托夫說：“這是一項(xiàng)驚人發(fā)現(xiàn),，兩個(gè)大腦網(wǎng)絡(luò)可以被同時(shí)激活。在此之前,，科學(xué)家一直認(rèn)為它們?cè)谝粋€(gè)被激活時(shí),，另一個(gè)處于休眠狀態(tài)。”志愿者越意識(shí)不到他們的思緒飄蕩,，兩個(gè)大腦網(wǎng)絡(luò)越能被激活,。
大腦活動(dòng)的數(shù)量和質(zhì)量表明，嘗試解決復(fù)雜問題的人應(yīng)該先停下來,，轉(zhuǎn)而從事更為簡(jiǎn)單的工作,，讓思緒自由飄蕩?？死锼雇蟹蛘f：“你在走神的時(shí)候,，可能并沒有取得直接目標(biāo)——比如在課堂上讀書或集中注意力聽講，但思緒可能利用這一時(shí)間去解決你人生中更為重要的問題,，比如事業(yè)發(fā)展或個(gè)人關(guān)系,。”（生物谷Bioon.com）
生物谷推薦原始出處：
PNAS May 11, 2009, doi: 10.1073/pnas.0900234106
Experience sampling during fMRI reveals default network and executive system contributions to mind wandering
Kalina Christoffa,1, Alan M. Gordonb, Jonathan Smallwoodc, Rachelle Smitha and Jonathan W. Schoolerc
Although mind wandering occupies a large proportion of our waking life, its neural basis and relation to ongoing behavior remain controversial. We report an fMRI study that used experience sampling to provide an online measure of mind wandering during a concurrent task. Analyses focused on the interval of time immediately preceding experience sampling probes demonstrate activation of default network regions during mind wandering, a finding consistent with theoretical accounts of default network functions. Activation in medial prefrontal default network regions was observed both in association with subjective self-reports of mind wandering and an independent behavioral measure (performance errors on the concurrent task). In addition to default network activation, mind wandering was associated with executive network recruitment, a finding predicted by behavioral theories of off-task thought and its relation to executive resources. Finally, neural recruitment in both default and executive network regions was strongest when subjects were unaware of their own mind wandering, suggesting that mind wandering is most pronounced when it lacks meta-awareness. The observed parallel recruitment of executive and default network regions—two brain systems that so far have been assumed to work in opposition—suggests that mind wandering may evoke a unique mental state that may allow otherwise opposing networks to work in cooperation. The ability of this study to reveal a number of crucial aspects of the neural recruitment associated with mind wandering underscores the value of combining subjective self-reports with online measures of brain function for advancing our understanding of the neurophenomenology of subjective experience.
