Department of Psychology, University of Toronto, Toronto ON, Canada.
Department of Behavioral Sciences, University of Michigan-Dearborn, Dearborn MI, USA.
Neuroimage. 2022 Oct 15;260:119497. doi: 10.1016/j.neuroimage.2022.119497. Epub 2022 Jul 20.
Scene construction is a key component of memory recall, navigation, and future imagining, and relies on the medial temporal lobes (MTL). A parallel body of work suggests that eye movements may enable the imagination and construction of scenes, even in the absence of external visual input. There are vast structural and functional connections between regions of the MTL and those of the oculomotor system. However, the directionality of connections between the MTL and oculomotor control regions, and how it relates to scene construction, has not been studied directly in human neuroimaging. In the current study, we used dynamic causal modeling (DCM) to interrogate effective connectivity between the MTL and oculomotor regions using a scene construction task in which participants' eye movements were either restricted (fixed-viewing) or unrestricted (free-viewing). By omitting external visual input, and by contrasting free- versus fixed- viewing, the directionality of neural connectivity during scene construction could be determined. As opposed to when eye movements were restricted, allowing free-viewing during construction of scenes strengthened top-down connections from the MTL to the frontal eye fields, and to lower-level cortical visual processing regions, suppressed bottom-up connections along the visual stream, and enhanced vividness of the constructed scenes. Taken together, these findings provide novel, non-invasive evidence for the underlying, directional, connectivity between the MTL memory system and oculomotor system associated with constructing vivid mental representations of scenes.
场景构建是记忆回忆、导航和未来想象的关键组成部分，依赖于内侧颞叶（MTL）。平行的研究表明，即使没有外部视觉输入，眼球运动也可以实现场景的想象和构建。MTL 和眼球运动系统的区域之间存在广泛的结构和功能连接。然而，MTL 和眼球运动控制区域之间的连接方向以及它与场景构建的关系尚未在人类神经影像学中直接研究。在当前的研究中，我们使用动态因果建模（DCM）来研究场景构建任务中 MTL 和眼球运动区域之间的有效连接，在该任务中，参与者的眼球运动受到限制（固定观察）或不受限制（自由观察）。通过排除外部视觉输入，并通过对比自由观察与固定观察，我们可以确定场景构建过程中神经连接的方向性。与眼球运动受到限制时相比，在构建场景时允许自由观察会增强从 MTL 到额眼区的自上而下的连接，并增强视觉流中的下向连接，从而增强构建场景的生动性。总的来说，这些发现为 MTL 记忆系统和与构建生动心理表象相关的眼球运动系统之间的潜在、定向连接提供了新颖的、非侵入性证据。
