Rice Nichola J, Valyear Kenneth F, Goodale Melvyn A, Milner A David, Culham Jody C
Volen Center for Complex Systems, Brandeis University, Waltham, MA, USA.
Neuroimage. 2007;36 Suppl 2:T87-93. doi: 10.1016/j.neuroimage.2007.03.032. Epub 2007 Mar 31.
It has been proposed that vision-for-perception and vision-for-action are subserved by distinct streams of visual processing, the ventral and dorsal stream, respectively [Milner, A. D., Goodale, M. A., 1995. The visual brain in action. Oxford University Press, Oxford]. Such a distinction has been supported by a recent functional magnetic resonance (fMR) adaptation study [Valyear, K. F., Culham, J. C., Sharif, N., Westwood, D., Goodale, M. A., 2006. A double dissociation between sensitivity to changes in object identity and object orientation in the ventral and dorsal visual streams: A human fMRI study. Neuropsychologia 44, 218-228], which demonstrated selectivity to object identity but not object orientation within the ventral stream, and selectivity to object orientation but not object identity within the dorsal stream. These results were interpreted as suggesting that changes to object identity (but not to orientation) would alter the representation of the stimulus in the perceptual/recognition system, whereas changes in object orientation (but not necessarily identity) would alter the coding of the stimulus within a visuomotor system concerned with behaviour such as grasping. If orientation sensitivity in the dorsal stream does reflect such a potential for action, then this sensitivity should be specific to graspable objects. Using an fMR adaptation paradigm, we presented participants with an image of either a graspable or non-graspable stimulus, followed by the same image in either the original orientation or its mirror image. One region within the dorsal stream, the lateral occipito-parietal junction (lOPJ), was shown to be sensitive to orientation changes for graspable stimuli; this region did not show orientation sensitivity for non-graspable stimuli. Thus, it appears that the sensitivity to orientation changes in this region is specific to graspable objects, presumably because such changes affect the affordances of graspable but not non-graspable objects.
有人提出，用于感知的视觉和用于行动的视觉分别由不同的视觉处理流，即腹侧流和背侧流来支持[米尔纳，A.D.，古德尔，M.A.，1995年。行动中的视觉大脑。牛津大学出版社，牛津]。最近一项功能磁共振（fMR）适应性研究[瓦尔耶尔，K.F.，卡尔汉姆，J.C.，沙里夫，N.，韦斯特伍德，D.，古德尔，M.A.，2006年。腹侧和背侧视觉流中对物体身份变化和物体方向变化的敏感性的双重分离：一项人类fMRI研究。神经心理学44，218 - 228]支持了这种区分，该研究表明腹侧流内对物体身份有选择性但对物体方向没有选择性，而背侧流内对物体方向有选择性但对物体身份没有选择性。这些结果被解释为表明物体身份的变化（而非方向的变化）会改变感知/识别系统中刺激的表征，而物体方向的变化（但不一定是身份的变化）会改变与诸如抓握等行为相关的视觉运动系统中刺激的编码。如果背侧流中的方向敏感性确实反映了这种行动潜力，那么这种敏感性应该特定于可抓握物体。使用fMR适应性范式，我们向参与者呈现可抓握或不可抓握刺激的图像，随后是相同图像的原始方向或其镜像。背侧流中的一个区域，即外侧枕顶交界区（lOPJ），被证明对可抓握刺激的方向变化敏感；该区域对不可抓握刺激没有显示出方向敏感性。因此，看来该区域对方向变化的敏感性特定于可抓握物体，大概是因为这种变化影响可抓握但不影响不可抓握物体的可供性。
