Neurophysiology of Saccade Adaptation: The Role of Superior Colliculus

描述（由申请人提供）：运动适应在发展过程中完善我们的运动，当我们试图获得新技能时调整它们，如果它们因受伤而受损，则修复它们。我们的长期目标是确定保持扫视眼球运动准确性的运动适应的神经机制。大多数（如果不是全部的话）关于扫视适应的神经生理学研究已经使用了响应于从中央凹脱落的目标的突然出现而进行的靶向（反应性）扫视，在此称为扫视的视网膜定位目标。对于目标扫视，视网膜定位目标和初始运动误差（目标和当前眼睛位置之间的差异[也称为期望扫视向量]）的向量是一致的。然而，扫视通常必须与其他扫视或其他类型的眼睛运动协调，这可能在执行对预期目标的扫视之前进行干预。这样的中断使要执行的扫视的向量与其视网膜定位目标分离，因此大脑必须执行空间更新以重新计算预期扫视的向量。我们使用双扫视任务（DST）的初步实验显示：（1）上级丘（SC）中扫视相关神经元的扫视爆发受到视网膜定位目标的调制，以及（2）出乎意料的是，靶向扫视的适应并不普遍化，即，转移到DST的第二次扫视，即使两次扫视具有相同的初始运动误差。这些发现使我们假设，SC使用不同的处理目标眼跳和眼跳，需要空间更新。我们将研究这种分离处理对眼跳适应的影响。 我们将使用三种方法来验证这一假设：1。行为实验，以推断目标眼跳和DST的第二眼跳的适应位点的基础上，每个适应的特点，并将其转移到其他类型的眼跳。2.单个单元记录，以揭示特定于两种不同扫视类型及其适应的SC活动的任何变化，以及3.微刺激和局灶失活，以测试SC地形活动的差异， 在这两个任务中执行扫视。 由于猿类与人类扫视性眼球运动行为的相似性，本项目的结果对扫视性眼球运动障碍患者的诊断、治疗和康复应该有相当大的相关性。我们提出的实验旨在提供行为和神经生理学的证据，适应眼跳相同的载体，但在不同的目标背景下产生的，不转移到对方，因此涉及不同的适应途径。了解不同情境下眼跳之间适应转移的局限性，可能有助于为眼跳障碍患者设计更具体的康复策略， 可能还有运动障碍

DESCRIPTION (provided by applicant): Motor adaptation refines our movements during development, adjusts them when we attempt to acquire a new skill, and repairs them if they are compromised by injury. Our long-term goal is to identify the neural mechanisms of the motor adaptation that maintains the accuracy of saccadic eye movements. Most, if not all, neurophysiological studies on saccade adaptation have used targeting (reactive) saccades made in response to the sudden appearance of a target that falls off the fovea, called here the retinotopic goal of the saccade. For targeting saccades, the vectors of the retinotopic goal and the initial motor error (the difference between the target and current eye positions [also called the desired saccade vector]) are congruent. However, saccades often must be coordinated with other saccades or other types of eye movement, which may intervene before a saccade to an intended goal is executed. Such interruptions dissociate the vector of the saccade to be executed and its retinotopic goal, so the brain must perform a spatial updating to re-compute the vector of the intended saccade. Our preliminary experiments using a double-saccade task (DST) revealed that (1) the saccadic burst of saccade-related neurons in the superior colliculus (SC) are modulated by the retinotopic goal, and (2) unexpectedly, adaptation of targeting saccades does not generalize i.e., transfer, to the second saccade of a DST, even when the two saccades have identical initial motor errors. These findings lead us to hypothesize that the SC uses different processing for targeting saccades and saccades that require spatial updating. We will examine the effect of this separate processing on saccade adaptation. We will use three approaches to test this hypothesis: 1. Behavioral experiments to infer the adaptation sites of targeting saccades and the second saccade of a DST on the basis of both the characteristics of each adaptation and its transfer to the other type of saccade. 2. single unit recording to reveal any changes in SC activity specific to the two different saccade types and their adaptations and 3. microstimulation and focal inactivation to test the difference of SC topographic activity during the execution of saccades in the two tasks . Because of the similarities of simian and human saccadic eye movement behavior, the results of this project should have considerable relevance in the diagnosis, treatment and rehabilitation of patients with saccadic eye movement disorders. Our proposed experiments aim to provide both behavioral and neurophysiological evidence that adaptation of saccades with the same vectors, but generated in different goal contexts, do not transfer to each other and hence involve different adaptation pathways. Understanding the limitation of the transfer of adaptation between saccades in different contexts may help to design a more specific repertoire of rehabilitation strategies for patients with saccade disorders, and perhaps general motor deficits.