Simons Jon S, Koutstaal Wilma, Prince Steve, Wagner Anthony D, Schacter Daniel L
Department of Psychology, Harvard University, Cambridge, MA 02138, USA.
Neuroimage. 2003 Jul;19(3):613-26. doi: 10.1016/s1053-8119(03)00096-x.
Previous functional imaging studies have shown that facilitated processing of a visual object on repeated, relative to initial, presentation (i.e., repetition priming) is associated with reductions in neural activity in multiple regions, including fusiform/lateral occipital cortex. Moreover, activity reductions have been found, at diminished levels, when a different exemplar of an object is presented on repetition. In one previous study, the magnitude of diminished priming across exemplars was greater in the right relative to the left fusiform, suggesting greater exemplar specificity in the right. Another previous study, however, observed fusiform lateralization modulated by object viewpoint, but not object exemplar. The present fMRI study sought to determine whether the result of differential fusiform responses for perceptually different exemplars could be replicated. Furthermore, the role of the left fusiform cortex in object recognition was investigated via the inclusion of a lexical/semantic manipulation. Right fusiform cortex showed a significantly greater effect of exemplar change than left fusiform, replicating the previous result of exemplar-specific fusiform lateralization. Right fusiform and lateral occipital cortex were not differentially engaged by the lexical/semantic manipulation, suggesting that their role in visual object recognition is predominantly in the visual discrimination of specific objects. Activation in left fusiform cortex, but not left lateral occipital cortex, was modulated by both exemplar change and lexical/semantic manipulation, with further analysis suggesting a posterior-to-anterior progression between regions involved in processing visuoperceptual and lexical/semantic information about objects. The results are consistent with the view that the right fusiform plays a greater role in processing specific visual form information about objects, whereas the left fusiform is also involved in lexical/semantic processing.
以往的功能成像研究表明，与初次呈现相比，视觉对象在重复呈现时（即重复启动）的加工过程更加顺畅，这与包括梭状回/枕叶外侧皮质在内的多个脑区神经活动的减少有关。此外，当重复呈现同一物体的不同示例时，也发现了神经活动的减少，但程度较轻。在之前的一项研究中，右侧梭状回相对于左侧梭状回，跨示例的启动减弱幅度更大，这表明右侧具有更高的示例特异性。然而，另一项先前的研究观察到梭状回的偏侧化受物体视角而非物体示例的调节。本功能磁共振成像（fMRI）研究旨在确定对于在感知上不同的示例，梭状回差异反应的结果是否能够被重复验证。此外，通过纳入词汇/语义操作，研究了左侧梭状回皮质在物体识别中的作用。右侧梭状回皮质显示出示例变化的影响显著大于左侧梭状回，重复了先前示例特异性梭状回偏侧化的结果。右侧梭状回和枕叶外侧皮质并未因词汇/语义操作而产生差异参与，这表明它们在视觉物体识别中的作用主要在于对特定物体的视觉辨别。左侧梭状回皮质而非左侧枕叶外侧皮质的激活受到示例变化和词汇/语义操作的调节，进一步分析表明，在处理有关物体的视觉感知和词汇/语义信息的脑区之间存在从后向前的进展。这些结果与以下观点一致，即右侧梭状回在处理有关物体的特定视觉形式信息方面发挥着更大的作用，而左侧梭状回也参与词汇/语义处理。
