Ganel Tzvi, Gonzalez Claudia L R, Valyear Kenneth F, Culham Jody C, Goodale Melvyn A, Köhler Stefan
Department of Psychology and CIHR Group on Action and Perception, University of Western Ontario, London, Ontario, Canada N6A 5C2.
Neuroimage. 2006 Sep;32(3):1432-40. doi: 10.1016/j.neuroimage.2006.05.039. Epub 2006 Jul 18.
Neuroimaging investigations of the cortically defined fMRI adaptation effect and of the behaviorally defined repetition priming effect have provided useful insights into how visual information is perceived and stored in the brain. Yet, although both phenomena are typically associated with reduced activation in visually responsive brain regions as a result of stimulus repetition, it is presently unknown whether they rely on common or dissociable neural mechanisms. In an event-related fMRI experiment, we manipulated fMRI adaptation and repetition priming orthogonally. Subjects made comparative size judgments for pairs of stimuli that depicted either the same or different objects; some of the pairs presented during scanning had been shown previously and others were new. This design allowed us to examine whether object-selective regions in occipital and temporal cortex were sensitive to adaptation, priming, or both. Critically, it also allowed us to test whether any region showing sensitivity to both manipulations displayed interactive or additive effects. Only a partial overlap was found between areas that were sensitive to fMRI adaptation and those sensitive to repetition priming. Moreover, in most of the object-selective regions that showed both effects, the reduced activation associated with the two phenomena were additive rather than interactive. Together, these findings suggest that fMRI adaptation and repetition priming can be dissociated from one another in terms of their neural mechanisms.
对皮层定义的功能磁共振成像适应效应和行为定义的重复启动效应进行的神经影像学研究，为视觉信息在大脑中如何被感知和存储提供了有益的见解。然而，尽管这两种现象通常都与由于刺激重复导致视觉反应性脑区激活减少有关，但目前尚不清楚它们是否依赖于共同的或可分离的神经机制。在一项事件相关功能磁共振成像实验中，我们正交地操纵了功能磁共振成像适应和重复启动。受试者对描绘相同或不同物体的刺激对进行比较大小判断；扫描过程中呈现的一些刺激对之前已经展示过，其他的则是新的。这种设计使我们能够检查枕叶和颞叶皮层中的物体选择性区域对适应、启动或两者是否敏感。至关重要的是，它还使我们能够测试任何对两种操纵都敏感的区域是否显示出交互或相加效应。在对功能磁共振成像适应敏感的区域和对重复启动敏感的区域之间仅发现了部分重叠。此外，在大多数显示出两种效应的物体选择性区域中，与这两种现象相关的激活减少是相加的而非交互的。总之，这些发现表明，功能磁共振成像适应和重复启动在神经机制方面可以相互分离。
