最近,，一篇發(fā)表于Proceedings of the National Academy of Sciences USA雜志的研究報(bào)告中,，西安大略大學(xué)的視覺神經(jīng)學(xué)專家Chris Striemer等人解開了一個(gè)謎團(tuán)：大腦是如何控制肢體避開障礙并準(zhǔn)確地取到想要的事物,。
在這項(xiàng)研究中,，研究對(duì)象是一位因大腦主要視覺區(qū)域中風(fēng),，導(dǎo)致左眼視力完全喪失但右眼正常的患者，研究人員要求其避開各種障礙獲取其右視覺區(qū)的目標(biāo)物,。顯然，他能成功地完成該測(cè)試,。但令人吃驚地是,，當(dāng)障礙物轉(zhuǎn)移到他的左邊盲區(qū)，他依然能夠避開障礙物。該患者的行為表明,，他在完全不知道障礙物的情況下,，對(duì)障礙物的位置也非常敏感。
這項(xiàng)發(fā)現(xiàn)證實(shí)了避障能力(obstacle avoidance)能繞開大腦內(nèi)主要的視覺區(qū)域而依賴于大腦內(nèi)原始的視覺通路,。因此,，即使我們大腦的視覺中心部分損傷，大腦的其他部分仍能保持有限的能力來利用眼睛獲得的視覺信息來控制肢體的運(yùn)動(dòng),。
此外,，研究人員還通過試驗(yàn)表明，這些原始的視覺通路僅能發(fā)揮功能是即時(shí)(real-time)的,，并不能進(jìn)入記憶系統(tǒng),。例如，在患者的盲區(qū)設(shè)置一個(gè)障礙物,，但時(shí)間是在他拿到之前兩秒鐘,，即使是在這么短的時(shí)間內(nèi)，患者的行為表明他已對(duì)物體的位置不具有敏感性,。（生物谷Bioon.com）
生物谷推薦原始出處：
PNAS September 2, 2009, doi: 10.1073/pnas.0905549106
“Real-time” obstacle avoidance in the absence of primary visual cortex
Christopher L. Striemer, Craig S. Chapman and Melvyn A. Goodale,1
Canadian Institutes of Health Research (CIHR) Group on Action and Perception, Centre for Brain and Mind, Department of Psychology, Social Sciences Centre, The University of Western Ontario, London, Ontario, Canada N6A 5C2
When we reach toward objects, we easily avoid potential obstacles located in the workspace. Previous studies suggest that obstacle avoidance relies on mechanisms in the dorsal visual stream in the posterior parietal cortex. One fundamental question that remains unanswered is where the visual inputs to these dorsal-stream mechanisms are coming from. Here, we provide compelling evidence that these mechanisms can operate in “real-time” without direct input from primary visual cortex (V1). In our first experiment, we used a reaching task to demonstrate that an individual with a dense left visual field hemianopia after damage to V1 remained strikingly sensitive to the position of unseen static obstacles placed in his blind field. Importantly, in a second experiment, we showed that his sensitivity to the same obstacles in his blind field was abolished when a short 2-s delay (without vision) was introduced before reach onset. These findings have far-reaching implications, not only for our understanding of the time constraints under which different visual pathways operate, but also in relation to how these seemingly “primitive” subcortical visual pathways can control complex everyday behavior without recourse to conscious vision.
