The role of parietal cortex in multisensory decision-making

描述（由申请人提供）：关于视觉刺激的决定经常受到其他感官形式的输入的影响。该提案的目标是更深入地了解能够整合视觉和听觉输入进行决策的神经机制。行为实验已经证实，受试者可以整合各种感官形式的信息，从而做出更好的决策。此外，受试者按其可靠性的比例对每种感觉模态进行加权。实验者可以估计受试者的“知觉 通过向两种感觉模态呈现冲突的信息并检查决策偏向一种模态或另一种模态的程度来确定“权重”。尽管有大量关于多感官刺激的行为后果的数据，但关于潜在的神经机制仍有许多未知之处。通过收集电生理和行为数据，我们处于一个理想的位置，将多感官决策与其潜在的神经机制联系起来。我的中心假设是，神经元对多感官刺激的刺激驱动调制比对单感官刺激的刺激驱动调制更大，并且我们通过比较单感官和多感官反应来估计的“神经权重”对于可靠和不可靠的刺激是相似的。后顶叶皮层是支持大鼠多感觉改善的候选区域：它接收来自听觉/视觉区域的输入，并在运动规划中发挥作用。在目标1中，我们将估计人类和大鼠在一项新的决策任务中的“感知权重”，在这项任务中，受试者判断一系列“事件”的总体速率：即闪光，点击或两者兼而有之。在目标2中，我们将收集大鼠后顶叶皮质的电生理数据，而他们从事的任务，以建立反应反映决策相关的活动。在目标3中，我们将在不同的刺激可靠性水平下测量单感觉刺激与多感觉刺激的反应。对于每个可靠性水平，我们将估计“神经权重，描述听觉与视觉输入的刺激驱动调制程度。如果神经权重，像感知权重一样，随着可靠性而变化，这表明刺激可靠性是由单个神经元明确编码的。相反，如果神经权重对于高可靠性刺激与低可靠性刺激保持不变，这将表明可靠性是由群体响应自动编码的，当它具有较低的增益时，群体响应自然变得更加可变。后一种可能性预测的最佳决策模型。

DESCRIPTION (provided by applicant): Decisions about visual stimuli are frequently shaped by inputs from other sensory modalities. The goal of this proposal is to gain a deeper understanding of the neural mechanisms that enable integration of visual and auditory inputs for decision-making. Behavioral experiments have established that subjects can integrate information across sensory modalities to make better decisions. Further, subjects weight each sensory modality in proportion to its reliability. Experimenters can estimate subjects' "perceptual weights" by presenting conflicting information to two sensory modalities and examining the degree to which decisions are biased toward one modality or the other. Despite a wealth of data about the behavioral consequences of multisensory stimuli, much remains unknown about the underlying neural mechanisms. By collecting electrophysiological and behavioral data together, we are in an ideal position to connect multisensory decision-making to its underlying neural mechanism. My central hypothesis is that neurons will show greater stimulus-driven modulation for multisensory stimuli than for unisensory stimuli and that the "neural weights" that we estimate by comparing unisensory and multisensory responses will be similar for reliable and unreliable stimuli. The posterior parietal cortex is a candidate area for supporting multisensory improvements in rats: it receives inputs from auditory/visual areas and plays a role in motor planning. In Aim 1, we will estimate humans' and rats' "perceptual weights" on a novel decision-making task in which subjects judge the overall rate of a stream of "events": i.e. flashes, clicks or both together. In Aim 2, we will collect electrophysiological data from posterior parietal corte of rats while they are engaged in the task to establish that responses reflect decision-related activity. In Aim 3, we will measure responses for unisensory vs. multisensory stimuli at different levels of stimulus reliability. For each level of reliability, we will estimate the "neural weights that describe the degree of stimulus-driven modulation for auditory vs. visual inputs. If the neural weights, like the perceptual weights, change with reliability, this would suggest that stimulus reliability is explicitly encoded by single neurons. If, instead, the neural weights remain unchanged for high- vs. low-reliability stimuli, this would suggest that reliability is automaticaly encoded by a population response that naturally become more variable when it has a lower gain. The latter possibility is predicted by an optimal model of decision-making.