【作者】 申林；

【导师】 谢鹏；

【作者基本信息】 重庆医科大学 ， 神经病学， 2008， 硕士

【摘要】 双稳态图形(如Necker立方体)是近年研究视觉意识常用的模型。当持续注视Necker立方体时,大脑会觉知到两种相互竞争的知觉,特定时刻只能觉知到一种知觉,并持续数秒,随即被另一种知觉所替代,这一过程称之为知觉翻转或内源性知觉翻转。在这一过程中,刺激物(Nekcer立方体)的物理属性没有发生任何改变,因此这一过程的神经生理就是视知觉意识的神经生理过程。目前的资料显示额顶叶皮质参与了双稳态图形的知觉翻转过程,并发挥一般性作用。我们使用功能磁共振方法验证这一观点,并尝试寻找是否存在其它皮质对双稳态图形知觉翻转过程有贡献及与额顶叶皮质功能的关系。使用修订后的不连续的刺激呈现序列,采集并比较知觉翻转过程的功能磁共振信号。功能磁共振结果显示(1)相对于内源性知觉稳定过程,内源性翻转过程除了激活额顶叶皮质以外,颞叶也有相同程度的激活(2)并且相对于外源性翻转过程,在内源性翻转过程时,右侧颞叶表现出更高的激活,而额顶叶皮质的激活程度却没有差异。双稳态图形的知觉翻转过程是有多个皮质脑区(包括额顶叶皮质,颞叶皮质)共同参与完成的,额顶叶对于双稳态图形的知觉翻转过程是必要的,贡献一般性的作用。右侧中间颞叶(并非双侧颞叶)对于双稳态图形的知觉翻转可能更为重要,并可能在多个皮质部位功能整合过程中发挥作用。更多还原

【Abstract】 Ambiguous figures (such as the Necker cube and Rubins face/vase) produce a type of bistable percepts that has been used for studying visual consciousness. When human observers prolong view ambiguous figures, two percepts mutually compete for perceptual dominance so that each percept is aware for a few seconds while the other is suppressed. The process is well known as perceptual reversal or endogenous reversal. As the alternation occurs in the absence of any changes in the stimulus itself, variation in brain activity can be directly related to conscious perception. These recent results indicated a general role for fronto-parietal areas in mediating the perceptual transitions experienced during bistable figures.We examine the hypothesis by using functional magnetic resonance imaging (fMRI) and try to explore‘extra’brain area possibly related to the process of perceptual reversal. The fMRI reveal that (1) in contrast to endogenous stability, event-related response were observed in fronto-parietal areas as well as temporal gyrus in endogenous reversal. However, (2) in contrast to exogenous reversal, response at higher level were observed in right temporal gyrus rather than in bilateral temporal gyrus and fronto-parietal cortex in endogenous reversal.The neural process of perceptual reversal of bistable figures is systematic interactions among fronto-parietal areas and temporal gyrus which bind functionally information together. A fronto-parietal network is required and subserves more genersal aspects in bistable visual perception. Moreover, right middle temporal gyrus may participate systemetic binding process as a key nod and contribute a important role to bistable visual perception.更多还原