Neural Correlates of Microsaccadic Suppression in the Primate Brain

人们经常惊讶地发现，他们的眼睛从不停止移动，即使他们盯着某样东西看。更令人惊讶的是，如果我们的眼睛停止移动，我们就会对静止的物体视而不见，这是由于大脑中一种被称为“神经适应”的过程。这就产生了视觉神经科学中的一个核心悖论：当我们凝视时，我们每秒会产生几次小的眼球运动，我们对此并不察觉，但如果没有这些运动，我们就会错过眼前的很多东西。此外，由于我们大约80%的时间都在注视着我们的视线，所以注视性眼球运动负责驱动我们大部分的视觉体验。因此，眼动的生理和感知对于理解克服神经适应和维持视觉意识的神经机制至关重要。鉴于这些运动足够大，我们应该很容易注意到它们，为什么视觉世界在注视期间保持感知稳定是一个谜。从我们的感知中消除这种位移的过程被称为“微眼球抑制”。（扫视是眼睛位置的大幅度移动。）然而，我们目前还不知道微跳是为了视觉还是为了运动系统的需要。在美国国家科学基金会的支持下，巴罗神经学研究所的苏珊娜·马丁内斯-康德博士及其同事将通过记录受试者观看各种视觉刺激时大脑视觉区域的神经活动来解决这一知识空白。为了确定运动系统输入在微眼跳抑制中的作用，该项目将比较微眼跳引起的神经活动与模拟微眼跳的刺激运动引起的神经活动。该项目还将研究在视觉错觉中发生的神经活动，在这种错觉中，微眼球抑制被挫败，称为“视觉抖动”。由于我们的许多视觉体验都发生在注视过程中，因此确定运动眼睛产生稳定感知的机制是一个基本问题，它将影响我们对整个视觉过程的理解。该研究将确定视觉和运动机制在微眼球抑制中的作用，并将其作用定位在视觉层次上。这项申请的资金将用于支持巴罗神经学研究所的一个新研究小组，该小组可以为本科生、研究生和博士后研究人员提供神经科学方面的培训机会。它将通过出版物向科学和非专业受众广泛传播研究成果，从而提高公众对科学的理解。

People are often surprised to learn that their eyes never stop moving, even when they fixate on something. It is even more surprising that if our eyes did stop moving, we would become blind to stationary objects due to a brain process called "neural adaptation". This gives rise to a central paradox in visual neuroscience: When we fix our gaze, we produce small eye movements several times each second, of which we are unaware, but without which we would miss much of what is right in front of our face. Further, since we fixate our gaze about 80% of the time, fixational eye movements are responsible for driving most of our visual experience. The physiology and perception of fixational eye movements are therefore critical to understanding the neural mechanisms that overcome neural adaptation and maintain visual awareness. Given that these movements are large enough that we should easily notice them, it is a mystery why the visual world remains perceptually stable during fixation. The process that removes such displacements from our perception is called "microsaccadic suppression". (A saccade is a large shift in eye position.) However, we don't currently know whether the microsaccades are present for the purposes of vision or for the needs of the motor system. With support from the National Science Foundation, Dr. Susana Martinez-Conde and colleagues at the Barrow Neurological Institute will address this gap in knowledge by recording the neural activity in visual brain areas, while subjects view various visual stimuli. To determine the role of motor system inputs in microsaccadic suppression, the project will compare the neural activity caused by microsaccades to the activity induced by stimulus motions that mimic microsaccades. The project will also examine the neural activity that occurs during a visual illusion in which microsaccadic suppression is foiled, called "visual jitter".Because much of our visual experience occurs during fixation, defining the mechanisms responsible for producing stable perception from a moving eye is a basic issue that will affect our understanding of the entire visual process. The proposed research will identify the contributions of visual versus motor mechanisms in microsaccadic suppression and localize their effects along the visual hierarchy. The funding from this application will be used to support a new research group at the Barrow Neurological Institute which can provide training opportunities in neuroscience for undergraduate, graduate and post-doctoral researchers. It will broadly disseminate results through publications to scientific as well as lay audiences, thus enhancing scientific understanding by the public.