Midbrain Mechanisms of Sensory-Guided Oculomotor Choice

项目摘要/摘要 本项目的目标是研究上丘(SC)对 选择行为；具体地说，我们建议在紧急决策任务的背景下这样做，该任务允许 我们要将知觉和运动表现分离开来，具有前所未有的巨大有效性。神经学家 我对选择行为进行了深入的研究，在许多任务中，做出了感性的判断，并且 然后是一份汽车报告。虽然非常成功，但这种方法也有局限性。最值得注意的是，各种秘密 注意力、预期、动机或任务难度等因素可以相互交换，创造 不能通过标准心理物理指标解决的模糊性，即反应时间和选择准确度。 因此，关于选择时机的根本问题仍然知之甚少。需要多长时间才能到达 做一个感性的判断而不是执行一个运动动作来报告它？在什么时间点是一个主题 致力于某一特定选项？当成功率增加时，是因为刺激的处理效率更高- 是更快还是更快，还是因为有更多的时间用于他们的分析？此项目中的PI是最近开发的 一项紧迫的选择任务，这些问题--以及潜在的神经机制--可以用来测试 以直接、毫不含糊的方式表达。它产生了一种新的心理物理测量，即测速曲线，它 描述受试者在一段时间内独立于运动执行的知觉表现。私家侦探也有 构建了一个计算模型，将神经元反应与受试者的行为联系起来，具有很大的量化能力 假设的细节。在拟议的实验中，将记录训练过的猴子的SC中的神经元活动 来完成这项新颖的跳跃选择任务。将解决两个问题。第一，公务员事务局局长的参与 与SC在扫视执行中牢固确立的角色相比，知觉处理仍然较少 很好的特点。测速曲线的独特性质将被用来确定何时每一次。 概念信息通知SC活动，以及这与受试者的 在任务执行过程中感知(目标1)。此外，还将注入亚阈值微刺激电流 使用各种空间和时间配置进入SC以确定人工诱发的活动 影响知觉和运动性能(目标2)。第二个问题是当选择行为改变时 它是由多感官刺激驱动的，也就是说，由视觉和听觉提示的同时呈现。这个 众所周知，SC对这种刺激组合的反应最有效，但它们在选择行为中的影响- 还没有评估IOR。这项任务的多感官变量将被用来确定多感官 整合改变了知觉判断或眼跳运动计划的速度(目标3)。这部作品 将提供关于感知信息如何动态转化为运动输出的批判性见解，将 描述神经元水平上的多感官整合如何导致行为表现的增强，以及 将决定SC如何参与这些过程。

Project Summary/Abstract The goal of this project is to investigate the perceptual and motor contributions of the superior colliculus (SC) to choice behavior; specifically, we propose to do this in the context of an urgent decision-making task that allows us to dissociate perceptual and motor performance with great, unprecedented effectiveness. Neuroscientists have intensely studied choice behavior with numerous tasks in which a perceptual judgement is made and is followed by a motor report. While highly successful, this approach has limitations. Most notably, various covert factors such as attention, anticipation, motivation or task difficulty can be traded against each other, creating ambiguities that cannot be resolved via standard psychophysical metrics, i.e., reaction time and choice accuracy. Thus, fundamental questions about the timing of choices remain poorly understood. How long does it take to make a perceptual judgement versus executing a motor action to report it? At what point in time is a subject committed to a particular option? When the success rate increases, is it because stimuli are processed more effi- ciently, or faster, or because more time is dedicated to their analysis? The PIs in this project recently developed an urgent-choice task with which these questions - and the underlying neural mechanisms - can be exam- ined in a direct, unambiguous way. It produces a new psychophysical measure, the tachometric curve, which characterizes a subject's perceptual performance over time independently of motor execution. The PIs have also constructed a computational model that relates neuronal responses to the subjects' behavior with great quanti- tative detail. In the proposed experiments, neuronal activity in the SC will be recorded from monkeys trained to perform this novel saccadic-choice task. Two problems will be addressed. First, the participation of the SC in perceptual processing, which in contrast to the SC's firmly established role in saccade execution, remains less well characterized. The unique properties of the tachometric curve will be exploited to determine when per- ceptual information informs the SC activity, and how this correlates with the temporal evolution of the subject's percept during task performance (Aim 1). In addition, subthreshold microstimulation current will be injected into the SC using various spatial and temporal configurations to determine how the artificially evoked activity impacts perceptual and motor performance (Aim 2). The second problem is how choice behavior changes when it is driven by multisensory stimuli; that is, by the simultaneous presentation of visual and auditory cues. The SC is known to respond most effectively to such stimulus combinations, but their impact during choice behav- ior has not been assessed. A multisensory variant of the task will be used to determine whether multisensory integration alters the speed of the perceptual judgements or of the saccadic motor plans (Aim 3). This work will provide critical insight about how perceptual information is dynamically translated into motor output, will characterize how multisensory integration at the neuronal level leads to enhanced behavioral performance, and will determine how the SC participates in these processes.