Hippocampal Involvement in Processing of Indistinct Visual Motion Stimuli
Hippocampal Involvement in Processing of Indistinct Visual Motion Stimuli
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DOI：
10.1162/jocn_a_00226
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发表时间：
2012-06-01
影响因子：
3.2
通讯作者：
Glasauer, Stefan
中科院分区：
文献类型：
--
作者：
Fraedrich, Eva M.;Flanagin, Virginia L.;Glasauer, Stefan
对已知模式的感知是当前感觉输入与现有内部表征相互作用的结果。当视觉输入是动态的和结构化的，以至于无法立即识别明显的对象和形式时，知觉和助记过程如何相互作用尚不清楚。在fMRI实验中，参与者在执行光流任务时，呈现了通过虚拟隧道描述运动的有意义的视觉运动刺激，以及通过对相同刺激进行相位加扰而获得的模糊的、无意义的视觉运动刺激。我们发现，我们模糊的视觉运动刺激会引起海马区的激活，而相应的有意义的刺激则不会。使用独立成分分析，我们能够证明海马体和早期视觉区域之间的功能连接，对模糊刺激的活动增加。在第二个实验中，我们使用相同的刺激来测试我们的结果是否取决于参与者的任务。我们发现任务无关的双侧海马区激活对模糊的运动刺激做出反应。在这两个实验中，心理生理交互作用分析显示，在观看模糊刺激时，从海马体后部到背侧视觉空间和腹侧视觉对象处理区域存在耦合。这些结果表明，依赖刺激的知觉过程和记忆过程之间存在着密切的功能联系。在没有外显记忆任务的情况下，观察到的海马区功能连接的模式表明，当视觉刺激在时间上不确定且不立即显示明确含义时，皮质-海马区网络被招募。
Perception of known patterns results from the interaction of current sensory input with existing internal representations. It is unclear how perceptual and mnemonic processes interact when visual input is dynamic and structured such that it does not allow immediate recognition of obvious objects and forms. In an fMRI experiment, meaningful visual motion stimuli depicting movement through a virtual tunnel and indistinct, meaningless visual motion stimuli, achieved through phase scrambling of the same stimuli, were presented while participants performed an optic flow task. We found that our indistinct visual motion stimuli evoked hippocampal activation, whereas the corresponding meaningful stimuli did not. Using independent component analysis, we were able to demonstrate a functional connectivity between the hippocampus and early visual areas, with increased activity for indistinct stimuli. In a second experiment, we used the same stimuli to test whether our results depended on the participants' task. We found task-independent bilateral hippocampal activation in response to indistinct motion stimuli. For both experiments, psychophysiological interaction analysis revealed a coupling from posterior hippocampus to dorsal visuospatial and ventral visual object processing areas when viewing indistinct stimuli. These results indicate a close functional link between stimulus-dependent perceptual and mnemonic processes. The observed pattern of hippocampal functional connectivity, in the absence of an explicit memory task, suggests that cortical-hippocampal networks are recruited when visual stimuli are temporally uncertain and do not immediately reveal a clear meaning.