Development of the multisensory computations underlying flavor processing

总结 食物是通过“味道”的多感官质量来感知和享受的，这涉及到味觉 和气味，但不容易分解成其组成部分。风味感知对食物有重要影响 选择，因此与健康直接相关。然而，潜在的神经机制仍然是神秘的。 以前对人类的研究表明，大脑积极地将味觉和嗅觉输入结合起来，以创造我们的视觉。 味道的感觉，这个过程在很大程度上取决于饮食经验。然而，人类成像 技术缺乏空间和时间分辨率，无法提供对神经回路如何 产生多感官风味表征。此外，人们高度主观的饮食史排除了一个 系统地了解经验如何推动风味加工的发展。克服这些 问题，本提案采取了独特的方法来研究风味。用清醒的，品尝的老鼠作为一个 动物模型使我们能够直接进入神经计算的基础上的味道处理在细胞 水平，并完全控制个人的风味体验。提出的假设直接建立在 我们最近在大鼠嗅觉皮层中跨通道风味加工方面的发现，以及几十年来在 在其他多感觉系统的皮层和皮层下区域发展多感觉计算。 该项目包括一系列连贯的实验，系统地寻求提供机械 了解整合与味道相关的感官信息的神经回路。具体来说，我们将回答 以下问题：1）嗅觉皮层回路整合味觉和味觉的指导原则是什么？ 嗅觉输入？为了解决这个问题，我们将使用电生理技术来记录嗅觉反应， 皮层神经元对味觉-嗅觉混合物及其单一感觉成分的反应; 2）皮层神经元对味觉-嗅觉混合物及其单一感觉成分的反应是如何进行的？ 嗅觉皮层回路执行的多感官操作是由特定口味的经验塑造的？ 为了解决这个问题，我们将实验性地操纵大鼠对特定味道-气味混合物的体验，并记录 嗅皮层神经元对一致、不一致和未暴露的味觉-嗅觉反应 混合物以及它们的unisensory成分;以及3）如何整合跨模态输入的能力 在整个生命周期中发展？为了解决这个问题，我们将跟踪嗅觉的单通道和跨通道反应， 大脑皮层在清醒的大鼠在不同阶段的早期出生后的发展;为了成功地实现这些 目标，我们独特的研究团队汇集了风味加工和唤醒啮齿动物的专业知识， 嗅觉皮质生理学（PI Maier）、多感觉交互的计算基础（Co-I Rowland），以及 多感觉系统的发展（Co-I Stein）。

SUMMARY Food is perceived and enjoyed through the multisensory quality of “flavor”, which involves the senses of taste and smell, but is not easily dissociated into its components. Flavor perception has a major influence on food choice and is thus directly linked to health. However, the underlying neural mechanisms remain mysterious. Previous work in humans has suggested that the brain actively combines taste and smell inputs to create our sense of flavor, and that this process depends heavily on eating experience. However, human imaging techniques lack spatial and temporal resolution to provide a mechanistic understanding of how neural circuits produce multisensory flavor representations. Moreover, people’s highly subjective eating history precludes a systematic understanding of how experience drives the development of flavor processing. To overcome these issues, the present proposal takes a unique approach to the study of flavor. Using the awake, tasting rat as an animal model allows us to directly access to the neural computations underlying flavor processing at the cellular level, and complete control over the individual’s flavor experience. The proposed hypotheses build directly on our own recent findings on cross-modal flavor processing in rat olfactory cortex, as well as decades of work on the development of multisensory computations in cortical and subcortical regions of other multisensory systems. The project comprises a coherent series of experiments that systematically seeks to provide mechanistic understanding of the neural circuits that integrate flavor-related sensory information. Specifically, we will answer the following questions: 1) What are the guiding principles by which olfactory cortical circuits integrate taste and smell inputs? To address this, we will use electrophysiological techniques to record responses from olfactory cortical neurons to taste-smell mixtures as well as their unisensory components in awake adult rats; 2) How are the multisensory operations performed by olfactory cortical circuits shaped by experience with specific flavors? To address this, we will experimentally manipulate rats’ experience with specific taste-smell mixtures, and record responses from ensembles of olfactory cortical neurons to congruent, incongruent and unexposed taste-smell mixtures as well as their unisensory components; and 3) How does the ability to integrate cross-modal inputs develop across the lifespan? To address this, we will track uni- and cross-modal responsiveness of olfactory cortex in awake rats across different stages of early postnatal development; To successfully achieve these objectives, our unique team of investigators brings together expertise in flavor processing and awake rodent olfactory cortex physiology (PI Maier), the computational basis of multisensory interactions (Co-I Rowland), and the development of multisensory systems (Co-I Stein).