Peripheral-to-foveal cortico-collicular processing of visual information across eye movements

眼球运动过程中视觉信息的外周至中心凹皮质-丘脑处理

• 批准号: 520283985
• 负责人: Professor Dr. Ziad Hafed, Ph.D.
• 金额: --
• 依托单位: Werner Reichardt-Centrum für integrative Neurowissenschaften (CIN)
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/520283985?language=en
• 关键词: Peripheral; foveal; cortico; collicular; processing

Saccadic eye movements cause substantial visual uncertainty due to the rapidity with which they translate images of the environment across the retina. Moreover, because a large portion of the visual system is organized retinotopically, every time a saccade occurs, neurons representing the foveal retinal image region in multiple brain areas experience a different post-saccadic scene portion than the scene portion that they experience before eye movement onset. This, coupled with the fact that post-saccadic sensory input arrives well after eye movement onset (due to long afferent processing delays and strong motion blur caused by saccades), suggests a need for a mechanism to bridge trans-saccadic visual processing. Such bridging needs to happen both in time (across saccade duration) as well as in space (linking a retinotopically peripheral pre-saccadic image of the eye movement target to a foveal post-saccadic version of it). Trans-saccadic peripheral-to-foveal transfer of visual information between different retinotopically organized populations of neurons could be a means to realize exactly such a bridge, and perceptual evidence for this transfer exists. In this project, we will unravel the cortical and subcortical mechanisms associated with trans-saccadic peripheral-to-foveal transfer of visual information. We will demonstrate that there is a predictive remapping of peripheral visual feature information of a stable saccade target to foveal visual representations in both the superior colliculus (SC) and primary visual cortex (V1). We will also causally demonstrate that such remapping can be jumpstarted in the SC motor bursts themselves (which are known to drive eye movements via downstream projections to brainstem and cerebellar motor control nuclei). This jumpstarting happens via embedding a sensory-tuned signal in the SC motor bursts, meaning that saccade commands in the SC simultaneously also represent the visual appearance of peripheral saccade targets. We argue that endowing SC motor bursts with such a sensory tuning signal allows the SC to provide visual areas with a peripheral scene preview for bridging perception; that is, because SC motor bursts are temporally coincident with saccades, the scene preview embedded in them is available exactly when vision (via sensory afference) is most uncertain (intra-saccadically). Finally, because the SC has ascending feedback projections to the cortex, we will investigate whether the SC’s sensory-tuned motor burst activity is critical for trans-saccadic remapping of visual features to the fovea at the cortical level, or whether cortico-cortical interactions (perhaps via area V4) are sufficient. Our experiments will reveal highly novel mechanistic insights on peripheral-to-foveal cortico-collicular processing of visual information across eye movements.

跳跃性眼球运动由于在视网膜上快速转换环境图像而导致视觉上的不确定性。此外，由于视觉系统的很大一部分是视网膜位置组织的，每次扫视发生时，代表多个脑区的中央凹视网膜图像区域的神经元经历的扫视后场景部分与眼动开始前的场景部分不同。这一点，再加上眼动后感觉输入在眼动开始后才到达（由于长时间的传入处理延迟和眼动引起的强烈运动模糊），表明需要一种机制来连接跨眼动视觉处理。这种桥接既需要在时间上发生（跨越扫视持续时间），也需要在空间上发生（将眼球运动目标的视网膜外周扫视前图像与扫视后中央凹图像连接起来）。在不同的视网膜组织的神经元群之间，视觉信息的跨扫视外周到中央凹转移可能是实现这种桥梁的一种手段，并且存在这种转移的感知证据。在这个项目中，我们将揭示与视觉信息从外周到中央凹的跨跳跃传递相关的皮层和皮层下机制。我们将证明，在上丘（SC）和初级视觉皮层（V1）中，稳定的扫视目标的周边视觉特征信息与中央凹视觉表征之间存在预测性的重新映射。我们还将证明，这种重新映射可以在SC运动爆发本身中启动（众所周知，SC运动爆发通过下游投射到脑干和小脑运动控制核来驱动眼球运动）。这种快速启动是通过在SC运动爆发中嵌入一个感觉调谐信号来实现的，这意味着SC中的扫视指令同时也代表了周边扫视目标的视觉外观。我们认为，赋予SC运动脉冲这样的感官调谐信号允许SC提供视觉区域与桥接感知的外围场景预览；也就是说，由于SC运动爆发与扫视在时间上是一致的，因此嵌入其中的场景预览恰好在视觉（通过感觉传入）最不确定的时候（在扫视内）可用。最后，因为SC有上升的反馈投射到皮层，我们将研究SC的感觉调节运动爆发活动是否在皮层水平上对视觉特征的跨皮层重新映射到中央凹至关重要，或者皮质-皮质相互作用（可能通过V4区）是否足够。我们的实验将揭示通过眼动对视觉信息的外周-中央凹皮质-丘处理的高度新颖的机制见解。