Effects of saccade-like image shifts on retinal processing: Phenomena, mechanisms, and relation to visual processing in higher brain centers

在自然观看期间，视网膜上的图像流动主要由观察者的行为决定。主动视觉探索中的眼球运动在这方面尤其占主导地位，特别是因为它们每秒不间断地发生3-5次。尽管如此，过去对视网膜图像处理的研究往往是孤立的刺激，忽略了自然视觉的高动态方面。在这个项目中，我们将探索眼动诱导的图像运动对视网膜信号处理的影响。我们将详细描述视网膜中与眼跳相关的反应调节，并将视网膜输出中看到的影响与视网膜受体脑区中描述的现象相关联。重要的是，我们将研究视网膜跳动反应调制的细胞机制。根据初步数据，我们预计，与单独呈现的相同刺激的反应相比，在眼跳背景下呈现的“测试刺激”的视网膜反应将受到强烈的调制。此外，我们将展示眼跳在长达1秒的时间内散发出它们的调节效应，这表明眼动诱导效应在自然条件下具有高度相关的作用，并伴随着短暂的眼跳注视。重要的是，我们将展示与眼跳相关的视网膜调制严重依赖于在眼跳过程中存在的背景场景的统计特性、环境亮度水平以及特定的视网膜细胞类型。例如，眼跳后，非神经节细胞的反应可以被正向调节，但在神经节细胞上却不能。这表明视网膜内的不同通路在扫视调制特性方面是不同的。因此，已知的高级视觉区域调制的多样性可能至少部分是由视网膜中看到的不同调制引起的。这个项目的独特之处在于，它将研究自然视觉条件下的视网膜信号处理，同时综合观察从视网膜到大脑的视神经元由扫视启动的反应调制。

During natural viewing, image flow on the retina is determined primarily by the behavior of the observer. Eye movements during active visual exploration are particularly dominating in this regard, especially because they incessantly occur 3-5 times per second. Despite this, retinal image processing has in the past often been studied with isolated stimuli, ignoring the highly dynamic aspects of natural viewing.In this project, we will explore the effects of eye-movement induced image motion on signal processing in the retina. We will characterize saccade-related response modulations in the retina in great detail, and we will correlate the effects seen in the retinal output to well-described phenomena in retina-recipient brain areas. Importantly, we will investigate the cellular mechanisms underlying saccadic response modulation in the retina. Based on preliminary data, we anticipate that retinal responses to "test stimuli" presented in the context of saccades will be strongly modulated in comparison to responses to the same stimuli presented in isolation. Moreover, we will show that saccades exude their modulatory effects for up to 1 second, suggesting a highly relevant role of eye-movement induced effects under natural conditions with short inter-saccadic fixations. Importantly, we will show that saccade-related retinal modulation critically depends on the statistical properties of the background scene present during the saccade, on the ambient luminance level, and on the specific retinal cell type. For example, the responses of OFF ganglion cells, but not ON ganglion cells, can be positively modulated after saccades. This suggests that the different pathways within the retina are distinct with respect to the properties of saccadic modulation. Thus, the diversity of modulations known from higher visual areas might be, at least in part, caused by the diverse modulations seen in the retina.This project is unique in that it will investigate retinal signal processing under conditions of natural viewing, while taking an integrated look at the saccade-initiated response modulation of visual neurons from retina to brain.