功能核磁共振大腦掃描顯示圖
據(jù)物理學家組織網(wǎng)報道，加拿大不列顛哥倫比亞大學一項最新研究結果發(fā)現(xiàn),，人在走神時大腦的活動反而比科學家以前想象的更為活躍,。
這項研究發(fā)現(xiàn)，當我們心不在焉的時候,，大腦很多區(qū)域的活動都有所增強,。研究結果刊登在最新一期美國《國家科學院院刊》（PNAS）上。事實上，該研究表明,，一些同解決復雜問題有關的大腦區(qū)域在我們進行天馬行空的想象時高度活躍,，而科學家之前認為這些區(qū)域在我們走神時處于休眠狀態(tài)。
領導實施這項研究的不列顛哥倫比亞大學心理學教授卡琳娜·克里斯托夫（Kalina Christoff）表示：“思緒飄揚一般同懶散或精力不集中等負面事情有關,。但是，這項研究卻表明我們走神時大腦活動反而更為活躍,，活躍程度甚至超過我們專心從事一些日常工作的時候,。”
在研究中，志愿者躺在fMRI掃描儀里面,，當數(shù)字出現(xiàn)在屏幕上時進行按鍵等簡單活動,。研究人員可以通過大腦掃描、志愿者的主動報告以及追蹤志愿者的成績來調(diào)查他們的瞬間注意力,。研究結果發(fā)現(xiàn),，走神(最多可以占據(jù)我們清醒狀態(tài)下三分之一的時間)是一種重要的認知狀態(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，科學家認為大腦的“默認網(wǎng)絡”是走神時大腦中唯一活躍的區(qū)域,。大腦“默認網(wǎng)絡”同日常輕松的智力活動有關,，包括內(nèi)側前額葉皮質(zhì)、后扣帶回皮質(zhì)和顳頂聯(lián)合區(qū)(temporoparietal junction),。但是,，這項研究卻發(fā)現(xiàn)，大腦的“執(zhí)行網(wǎng)絡”在我們走神時也會被激活,。大腦“執(zhí)行網(wǎng)絡”負責解決高度復雜的問題,，由側面前額葉皮質(zhì)和背面后扣帶回皮質(zhì)構成。
克里斯托夫說：“這是一項驚人發(fā)現(xiàn),，兩個大腦網(wǎng)絡可以被同時激活,。在此之前，科學家一直認為它們在一個被激活時,，另一個處于休眠狀態(tài),。”志愿者越意識不到他們的思緒飄蕩，兩個大腦網(wǎng)絡越能被激活,。
大腦活動的數(shù)量和質(zhì)量表明,，嘗試解決復雜問題的人應該先停下來，轉(zhuǎn)而從事更為簡單的工作,，讓思緒自由飄蕩,。克里斯托夫說：“你在走神的時候，可能并沒有取得直接目標——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)展或個人關系。”（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.
