據(jù)physorg網(wǎng)站2006年8月2日報道,，畫家訓練過的眼神可以區(qū)別常人無法區(qū)別的差別；音樂家可以辨別出細微的跑調(diào)。大腦研究人員將這種能力稱之為感性學習能力,。
在研究中獲得一次意外發(fā)現(xiàn)后,，美國麻省理工學院皮庫爾學習和記憶研究所研究員和他們研究伙伴們共同合作破解了這一現(xiàn)象的機理。該研究發(fā)現(xiàn)將刊登在8月3日出版的《神經(jīng)元》期刊上,。
他們最初是想研究視力喪失對大腦的影響,。但是實驗中老鼠視力喪失之前，研究人員使用基線測量法進行測量的儀器屏幕上卻出現(xiàn)了一種斑紋圖案,。非常令人感到意外的是,，研究人員發(fā)現(xiàn)盡管這個圖案在觀察期沒有什么變化，但是在過了僅僅12小時后,，老鼠視力越發(fā)與這種圖案相“協(xié)調(diào)”,。在經(jīng)過幾個觀察期后，老鼠大腦中斑紋的反應增強,，當老鼠的視力超出正常時斑紋反應達到最強,。研究人員將這種變化稱之為“刺激選擇性反應增強(SRP)”。
皮庫爾研究所神經(jīng)系統(tǒng)科學教授和此項研究的參與者之一馬克·比爾說,，“刺激選擇性反應增強的特性與一些人類感性學習模式有著驚人的相似”,。因此，此種類型感性學習的研究非常重要,，因為它可以破解內(nèi)隱記憶形式的機理,，可能應用于促進大腦損傷后的恢復。詳細了解大腦化學變化的形式可能會幫助創(chuàng)造出新的大腦藥理和行為療法,，從而促進大腦中的這些化學變化,。
同時還在麻省理工學院大腦和認知科學系任職的比爾說，“大腦研究人員已經(jīng)對感性學習進行了很長時間的研究,，但是直到現(xiàn)在,，還沒有任何研究觸及到感性學習背后的機理”。
研究人員已經(jīng)確定發(fā)現(xiàn)了位于大腦視覺皮層,，負責神經(jīng)鍵之間的傳輸,，連接神經(jīng)元和引發(fā)刺激選擇性反應增強的新型神經(jīng)傳遞素受體。由學習引發(fā)的大腦變化能增強神經(jīng)鍵,。
在麻省理工學院進行的此項研究中,，年青和成年老鼠大腦中均出現(xiàn)感性學習表明年齡增長不會導致敏銳感覺器官理解能力的喪失。
此項研究小組成員除了比爾還包括皮庫爾研究所博士后邁克黑爾·弗倫克爾,、俄勒岡衛(wèi)生科學大學的納撒尼爾·索特爾,、里約聯(lián)邦大學的安東尼婭·西尼拉·迪沃果、皮庫爾研究所博士后邦瓊·尤恩和麥克林醫(yī)院的拉恰爾·勒維,。
英文原文：
Researchers uncover basis for perceptual learning
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The artist's trained eye can detect distinctions others can't; musicians pick up subtle changes in tone lost on the nonmusical. Brain researchers call these abilities perceptual learning.
Following up on an accidental finding, MIT researchers at the Picower Institute for Learning and Memory and colleagues have uncovered a mechanism for this phenomenon. The study will appear in the Aug. 3 issue of Neuron.
The original idea was to look at how visual deprivation affects the brain. But before mice in the experiment were deprived of vision, researchers recorded baseline measurements by showing them a striped pattern on a video screen.
Unexpectedly, the researchers found that although no change showed up during the viewing session, as few as 12 hours later the mice were more visually "tuned" to the pattern they had seen. Over several sessions, the mice's brain responses to the stripes increased, with the biggest responses occurring to stripes the mice saw more often. The researchers dubbed this change "stimulus selective response potentiation" or SRP.
"The properties of SRP are strikingly similar to those described for some forms of human perceptual learning," said Mark Bear, Picower Professor of Neuroscience and co-author of the study. As a result, "understanding this type of perceptual learning is important because it can reveal mechanisms of implicit memory formation and might be exploited to promote rehabilitation after brain damage. Detailed knowledge of how practice changes brain chemistry is likely to suggest new pharmacological and behavioral therapies to facilitate these changes.
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"Brain researchers have studied perceptual learning for a long time, but until now, there has never been any insight into the mechanism behind it," said Bear, who also holds an appointment in MIT's Department of Brain and Cognitive Sciences.
The researchers specifically discovered that new neurotransmitter receptors are delivered to synapses, the connections among neurons, in the brain's visual cortex, leading to SRP. Changes in the brain triggered by learning strengthen the synapses.
In the MIT study, perceptual learning occurred in both young and adult mice, implying that the ability to sharpen sensory perception is not lost with aging.
In addition to Bear, authors include Mikhail Y. Frenkel, Picower Institute postdoctoral associate; Nathaniel B. Sawtell of Oregon Health and Sciences University; Antonia Cinira M. Diogo of the Universidade Federal do Rio de Janeiro; Picower Institute postdoctoral associate Bongjune Yoon; and Rachael L. Neve of McLean Hospital.
