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，通常需要经过一段时间的权衡和积累不确定的证据，然后才能采取行动。我们对负责这一证据积累过程的神经机制的大部分了解来自于对猴子进行的神经生理学研究，这些猴子执行要求苛刻的知觉决策任务。在一个特别研究得很好的模型中，猴子被训练来决定噪声视觉刺激的运动方向，并通过眼球运动来指示它们对位于感知到的运动方向上的目标的决定。这些研究表明，顶叶皮质外侧顶内区(LIP)的神经元在积累噪声运动证据以指导眼动反应方面发挥了作用。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编码关于运动方向的决定是否独立于运动动作，或者它是否反映了可以获取相关知觉信息的动眼运动选择过程？我们的中心假设是，LIP编码了一个眼动选择过程。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有关，而不是位置(红色代表向右运动，绿色代表向左运动)。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。关键的是，我们操纵了分配颜色的时间，并测量了对嘴唇中证据积累的表征的影响。当颜色分配发生在运动观看之前时，可以直接使用方向决定来选择适当的眼球运动响应，并且嘴唇可能被参与。当颜色分配发生在运动观看之后，在决策形成时，特定的眼球运动反应是未知的，并且嘴唇可能不参与。当颜色分配发生在运动观看时，嘴唇神经元可能能够动态地进入大脑其他地方正在进行的证据积累过程。这些结果将阐明LIP在知觉决策中的作用，并提供对支配行为环境如何影响大脑中决策等高级能力产生方式和位置的原则的更一般理解。 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，公众健康有望直接受益，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.