Midbrain Mechanisms of Sensory-Guided Oculomotor Choice

项目总结/摘要 本研究的目的是探讨上级丘（SC）对认知和运动的贡献， 选择行为;具体来说，我们建议在紧急决策任务的背景下这样做， 我们以前所未有的巨大有效性将知觉和运动表现分离开来。神经学家 我深入研究了选择行为，在许多任务中，做出了感性的判断， 然后是一个电机报告。虽然这种方法非常成功，但也有局限性。最值得注意的是， 注意力、预期、动机或任务难度等因素可以相互交换， 不能通过标准的心理物理度量来解决的模糊性，即，反应时间和选择准确性。 因此，关于选择时机的基本问题仍然知之甚少。要多长时间 做出知觉判断还是执行运动动作来报告？在什么时间点上一个对象 承诺一个特定的选择？当成功率增加时，是因为刺激被更有效地处理， 或者更快，或者因为更多的时间用于分析？该项目中的PI最近开发了 一个紧急选择任务，可以检查这些问题-以及潜在的神经机制- 以一种直接的，明确的方式。它产生了一种新的心理物理测量，转速曲线， 表征受试者随时间的感知表现，与运动执行无关。PI还 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， 细节在所提出的实验中，将从训练的猴子记录SC中的神经元活动。 来完成这个新颖的扫视选择任务。将讨论两个问题。第一，常设委员会参与 知觉处理，这与SC在眼跳执行中牢固确立的作用相反，仍然较少 很好的描述。转速曲线的独特属性将被利用，以确定何时每- 知觉信息告知SC活动，以及这如何与主体的时间演变相关。 在任务执行过程中保持清醒（目标1）。此外，将注入阈下微刺激电流 使用各种空间和时间配置进入SC，以确定人工诱发的活动如何 影响知觉和运动表现（目标2）。第二个问题是， 它是由多感官刺激驱动的;也就是说，通过视觉和听觉线索的同时呈现。的 已知SC对这种刺激组合的反应最有效，但它们在选择过程中的影响是不确定的。 尚未对高级督察进行评估。该任务的多感官变体将用于确定多感官 整合改变了感知判断或扫视运动计划的速度（目标3）。这项工作 将提供关于感知信息如何动态转化为运动输出的关键见解，将 表征神经元水平的多感觉整合如何导致增强的行为表现，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.