Stable perception of external stimuli over time: oculo-motor and visual processing mechanisms

6亿年前，当生活在海底的动物开始活动时，它们面临着一个重要的进化挑战：一方面，自我运动具有明显的优势：例如，寻找新的食物来源和躲避捕食者。另一方面，它引入了关于感觉输入来源的模棱两可。当你过马路时，你需要区分一个动作是由汽车的移动引起的(需要避免)，还是由你过马路引起的被动运动(可以忽略)。任何未能正确识别感官刺激来源的动物都会面临进化上的劣势，造成毁灭性的后果。成功解决这个问题的物种通过跟踪它们的运动命令并通知感官系统即将到来的运动来解决这个问题。眼球运动是由运动系统引起的特定感觉变化的一个范例。如果我们要准确地感知眼前的世界，视觉场景就会看起来是一系列频繁而巨大的跳跃，使得它们之间不可能有任何匹配的尝试。对于视觉系统来说，能够区分由于扫视而引起的跳跃，而不是外部世界的变化，这是至关重要的。据认为，运动系统为感觉系统提供即将到来的运动的警告，中枢神经系统对此做出补偿机制。来自猴子神经生理学的证据表明，几个大脑位置特别涉及眼动系统和视觉之间的相互作用，即：猴额叶皮质的额叶和辅助眼区，顶叶皮质的几个部分和运动敏感区。我们对猴子新皮质这些区域的精细组织原理有大致的了解，但到目前为止，同样的原理还没有在人类皮质的同源区进行测试。这反映了标准人类神经成像技术固有的局限性。在标准的人类神经成像研究中，空间分辨率太粗糙，无法描述猴子神经生理学中通常观察到的详细空间组织。超高场成像(7特斯拉)有助于克服这些技术限制，提供比标准神经成像采集更好、更详细的信号。这些优势允许进行更详细的研究，这是在较低的视野(1.5特斯拉和3特斯拉)下无法成像的，从而打开了在人体体内测试猴子神经生理学中描述的精细眼球运动处理原理的可能性。

When the animals populating the floor of the ocean started moving 600 million years ago, they faced an important evolutionary challenge: on one hand self-motion carry clear advantages: for example, finding new sources of food and escaping predators. On the other hand, it introduces ambiguity about the source of a sensory input. When you are crossing the street, you need to differentiate whether a motion is caused by a movement of a car (that need to be avoided), or a passive movement caused by you crossing the street (which can be ignored).Any animal that failed to correctly recognize the source of a sensory stimulation would have faced an evolutionary disadvantage, with devastating consequences.The species that successfully solved this problem did so by keeping track of their movement commands and informing the sensory system about forthcoming movements. Eye movements are a paradigmatic example of a specific sensory change, induced by the motor system. If we were to perceive the world exactly as it is displayed if front of our eyes, the visual scene would seem a sequence of frequent and large jumps, making any matching attempts between them impossible. It is crucial for the visual system to be able to distinguish 'jumps' that are due to saccades as opposed to changes in the external world. It is believed that the motor system provides the sensory system with a warning of an upcoming movement, to which the central nervous system responds with a compensatory mechanism.Evidence from monkey neurophysiology shows that several brain locations are particularly involved in the interaction between the oculo-motor system and vision, namely: the frontal and supplementary eye fields in monkey frontal cortex, several portions of the parietal cortex and motion sensitive areas.We have a general understanding of the fine organizational principles of these areas in monkey neocortex, but the same principles have not been tested in homologue areas of human cortex, so far.This reflects limitations intrinsic to standard human neuroimaging techniques. The spatial resolution in standard human neuroimaging studies is too coarse to characterize the detailed spatial organization typically observed in monkey neurophysiology. Ultra-high field imaging (7Tesla) helps overcoming these technical limitations, providing better and more detailed signal than standard neuroimaging acquisition. These advantages allow for a more detailed investigation that is not possible to image at lower fields (1.5 and 3Tesla), opening the possibility to test in humans, in vivo, the fine oculomotor-processing principles described in monkey neurophysiology.