Visuomotor integration and perceptual decision-making in monkey parietal cortex

描述（由申请人提供）：决策是一种重要的认知能力，通常需要在采取行动之前权衡和积累不确定的证据。我们对负责这一证据积累过程的神经机制的理解，大部分来自对猴子执行要求苛刻的知觉决策任务的神经生理学研究。在一个特别研究的模型中，猴子被训练来决定嘈杂视觉刺激的运动方向，并通过眼睛移动到位于感知运动方向上的目标来指示它们的决定。这些研究表明，顶叶皮层外侧顶内区（LIP）的神经元在积累用于指导眼反应的噪声运动证据中发挥作用。然而，在这项任务中，方向决定的形成和适当的眼动反应的选择之间的密切关系使得很难确定LIP的确切作用。特别是，LIP编码的运动方向的决定独立于运动行为，或者它反映了一个眼选择过程，可以访问相关的感知信息？我们的中心假设是，LIP编码的眼选择过程。为了验证这一假设，我们将使用一种创新的任务设计来训练猴子，在这种任务设计中，猴子对运动方向的决定与选择目标的颜色而不是位置相关联（红色代表快速运动，绿色代表快速运动）。对于给定的会话，两个目标的位置是固定的，但我们随机为它们分配两种颜色。关键是，我们操纵的时间时，颜色被分配和测量的影响，在LIP的证据积累的代表性。当颜色分配发生在运动观看之前时，方向决定可以直接用于选择适当的眼动响应，并且LIP可能被占用。当在运动观看之后发生颜色分配时，在形成决策时不知道特定的眼动响应，并且LIP可能不参与。当颜色分配发生在运动观察过程中时，LIP神经元可能能够动态访问大脑其他地方正在进行的证据积累过程。研究结果将阐明LIP在感知决策中的作用，并提供对行为环境如何影响大脑中决策等高阶能力产生的方式和位置的原理的更普遍的理解。 公共卫生相关性：拟议的工作是基础研究，旨在为健康的神经系统如何评估证据以形成决策提供新的见解。因此，从长远来看，对公共卫生的直接好处预计将到来，因为这些新的见解可以用来设计新的方法来诊断和治疗影响感知和判断的疾病。

DESCRIPTION (provided by applicant): Decision-making is an important cognitive ability that often requires uncertain evidence to be weighed and accumulated over time before committing to a course of action. Much of our understanding of the neural mechanisms responsible for this process of evidence accumulation comes from neurophysiological studies in monkeys performing demanding perceptual decision- making tasks. In one particularly well-studied model, monkeys are trained to decide the direction of motion of a noisy visual stimulus and indicate their decision with an eye movement to a target located in the perceived direction of motion. These studies suggest that neurons in the lateral intraparietal area (LIP) of parietal cortex play a role in accumulating noisy motion evidence used to instruct the oculomotor response. However, in this task the close relationship between formation of the direction decision and selection of the appropriate oculomotor response makes it difficult to identify the exact role of LIP. In particular, does LIP encode the decision about motion direction independent of the motor act, or does it reflect an oculomotor selection process that can access relevant perceptual information? Our central hypothesis is that LIP encodes an oculomotor selection process. To test this hypothesis we will train monkeys using an innovative task design in which their decision about the direction of motion is associated with the color, instead of the location, of the choice target (red for rightward motion, green for leftward). For a given session the locations of the two targets are fixed, but we randomly assign to them the two colors. Critically, we manipulate the time when the colors are assigned and measure the effects on the representation of evidence accumulation in LIP. When the color assignment occurs before motion viewing, the direction decision can be used directly to select the appropriate oculomotor response and LIP is likely to be engaged. When the color assignment occurs after motion viewing, the specific oculomotor response is not known while the decision is formed and LIP might not be engaged. When the color assignment occurs during motion viewing, LIP neurons might be able to gain dynamic access to a process of evidence accumulation that is being carried out elsewhere in the brain. The results will clarify the role of LIP in perceptual decision-making and provide a more general understanding of the principles that govern how behavioral context can influence how and where in the brain high-order abilities like decision-making are generated. PUBLIC HEALTH RELEVANCE: The proposed work is basic research, designed to provide new insights into how a healthy nervous system evaluates evidence to form a decision. Thus, direct benefits to public health are expected to come in the longer term, as these new insights can be used to design new ways to diagnose and treat disorders that affect perception and judgment.