北京師范大學(xué)認(rèn)知神經(jīng)科學(xué)與學(xué)習(xí)國家重點實驗室李武老師及其博士生張恩二人在PNAS雜志上發(fā)表重要學(xué)術(shù)文章,。李武老師及其博士生張恩二人在2010年9月7日出版的PNAS雜志上發(fā)表了重要學(xué)術(shù)文章,。
視覺信息的加工在很大程度上依賴于視網(wǎng)膜坐標(biāo)系，可是在表征外界刺激的空間位置時,，視覺系統(tǒng)需要獨立于視網(wǎng)膜坐標(biāo)的編碼機(jī)制,，這對于多種感覺信息的整合以及感覺-運動整合至關(guān)重要；此外,，眼動和頭動會導(dǎo)致圖像在視網(wǎng)膜上變動,，而非網(wǎng)膜坐標(biāo)系下的加工機(jī)制可以確保視知覺的穩(wěn)定。因而,，視覺信息的非網(wǎng)膜坐標(biāo)表征一直是視覺研究的熱點。但是，目前還沒有研究者探討過非網(wǎng)膜坐標(biāo)下的視覺表征是否具有經(jīng)驗依賴性,。然而,，人的視覺檢測和分辨能力會隨著訓(xùn)練而逐漸提高。這種知覺學(xué)習(xí)現(xiàn)象通常特異于訓(xùn)練過的視網(wǎng)膜（或視野）位置,，也即,，學(xué)習(xí)的效果不能從訓(xùn)練過的位置遷移到?jīng)]有訓(xùn)練過的位置。但是,，傳統(tǒng)的知覺學(xué)習(xí)研究往往是在眼睛注視方向不變的情況下進(jìn)行,，不能區(qū)分知覺學(xué)習(xí)是單純視網(wǎng)膜位置特異的，還是依賴于刺激的非網(wǎng)膜位置,。
李武與其合作者的最新研究通過巧妙的實驗設(shè)計,，獨立改變刺激的視網(wǎng)膜和空間位置，探討了知覺學(xué)習(xí)位置特異性的參考坐標(biāo)系,。研究發(fā)現(xiàn),，除網(wǎng)膜特異性之外，知覺學(xué)習(xí)也是空間坐標(biāo)特異的,，依賴于訓(xùn)練刺激在空間坐標(biāo)系下的相對位置,，但并不受限于刺激的絕對空間位置。這一發(fā)現(xiàn)表明,，訓(xùn)練不僅能改變基于視網(wǎng)膜坐標(biāo)的編碼機(jī)制,，而且能特異地改變基于非網(wǎng)膜坐標(biāo)的信息加工。
這一研究大大加深了人類對知覺學(xué)習(xí),、視覺系統(tǒng)的可塑性,、以及非網(wǎng)膜坐標(biāo)系下動態(tài)視覺信息加工的理解和認(rèn)識。（生物谷Bioon.com）
生物谷推薦英文摘要：
PNAS doi: 10.1073/pnas.1003547107
Perceptual learning beyond retinotopic reference frame
En Zhang and Wu Li1
Repetitive experience with the same visual stimulus and task can remarkably improve behavioral performance on the task. This well-known perceptual-learning phenomenon is usually specific to the trained retinal- or visual-field location, which is taken as an indication of plastic changes in retinotopic visual areas. In previous studies of perceptual learning, however, a change in stimulus location on the retina is accompanied by positional changes of the stimulus in nonretinotopic frames of reference, such as relative to the head and other objects. It is unclear, therefore, whether the putative location specificity is exclusively retinotopic or if it could also depend on nonretinotopic representation of the stimulus, which is particularly important for multisensory and sensorimotor integration as well as for maintenance of stable visual percepts. Here, by manipulating subjects’ gaze direction to control spatial and retinal locations of stimuli independently, we found that, when the stimulated retinal regions were held constant, the improvement with training in motion-direction discrimination of two successively displayed stimuli was restricted to the relative spatial position of the stimuli but independent of their absolute locations in head- and world-centered frame. These findings indicate location specificity of perceptual learning beyond retinotopic frame of reference, suggesting a pliable spatiotopic mechanism that can be specifically shaped by experience for better spatiotemporal integration of the learned stimuli.
