雖然我們能夠在工作視覺記憶中記住幾個不同目標(biāo),，但我們是怎樣記住每個目標(biāo)的特定細(xì)節(jié)及視覺特征的仍是一個謎。對工作記憶負(fù)責(zé)的高級區(qū)域中的神經(jīng)元似乎對視覺細(xì)節(jié)并沒有選擇性,，大腦皮層的早期視覺區(qū)域具有能夠處理來自眼睛的輸入視覺信號的獨特能力,，但過去人們認(rèn)為它不能執(zhí)行如記憶等高級認(rèn)知功能。
Stephanie Harrison 和 Frank Tong等人,，利用對來自功能性核磁共振成像(fMRI)的數(shù)據(jù)進(jìn)行解碼的一種新方法,，發(fā)現(xiàn)早期視覺區(qū)域能夠保持關(guān)于存放在工作記憶中的相關(guān)特征的特定信息。研究人員向志愿者出示了兩個不同取向的條紋圖案,，要他們在被fMRI掃描時記住其中一個取向,。從對掃描結(jié)果所做的分析，研究人員有可能預(yù)測,，在兩個取向的圖案中的哪一個中,，一個目標(biāo)在超過80%的測試中都會被保留,。（生物谷Bioon.com）
生物谷推薦原始出處：
Nature 458, 632-635 (2 April 2009) | doi:10.1038/nature07832
Decoding reveals the contents of visual working memory in early visual areas
Stephenie A. Harrison1 & Frank Tong1
Psychology Department and Vanderbilt Vision Research Center, Vanderbilt University, Nashville, Tennessee 37240, USA
Visual working memory provides an essential link between perception and higher cognitive functions, allowing for the active maintenance of information about stimuli no longer in view1, 2. Research suggests that sustained activity in higher-order prefrontal, parietal, inferotemporal and lateral occipital areas supports visual maintenance3, 4, 5, 6, 7, 8, 9, 10, 11, and may account for the limited capacity of working memory to hold up to 3–4 items9, 10, 11. Because higher-order areas lack the visual selectivity of early sensory areas, it has remained unclear how observers can remember specific visual features, such as the precise orientation of a grating, with minimal decay in performance over delays of many seconds12. One proposal is that sensory areas serve to maintain fine-tuned feature information13, but early visual areas show little to no sustained activity over prolonged delays14, 15, 16. Here we show that orientations held in working memory can be decoded from activity patterns in the human visual cortex, even when overall levels of activity are low. Using functional magnetic resonance imaging and pattern classification methods, we found that activity patterns in visual areas V1–V4 could predict which of two oriented gratings was held in memory with mean accuracy levels upwards of 80%, even in participants whose activity fell to baseline levels after a prolonged delay. These orientation-selective activity patterns were sustained throughout the delay period, evident in individual visual areas, and similar to the responses evoked by unattended, task-irrelevant gratings. Our results demonstrate that early visual areas can retain specific information about visual features held in working memory, over periods of many seconds when no physical stimulus is present.
