Development of the multisensory computations underlying flavor processing

摘要 食物是通过“味”的多感官特性来感知和享用的，它涉及到味觉 和气味，但不容易分解成它的成分。味觉对食物有很大的影响 因此，它与健康直接相关。然而，潜在的神经机制仍然是个谜。 以前在人类身上的研究表明，大脑主动结合味觉和嗅觉输入来创造我们的 味觉，这一过程在很大程度上取决于进食体验。然而，人类成像 技术缺乏空间和时间分辨率来提供对神经回路如何的机械理解 产生多感官的味道表现。此外，人们高度主观的进食史排除了 系统地了解经验如何推动风味加工的发展。要克服这些障碍 对于这些问题，本提案采用了一种独特的方法来研究风味。用清醒的、品尝的老鼠作为 动物模型允许我们直接访问细胞中潜在的味道处理的神经计算 水平，并完全控制个人的口味体验。提出的假设直接建立在 我们自己关于大鼠嗅觉皮质跨模式风味加工的最新发现，以及几十年来在 在其他多感觉系统的皮质和皮质下区域的多感觉计算的发展。 该项目包括一系列连贯的实验，系统地寻求提供机械性的 了解整合与味道相关的感觉信息的神经回路。具体地说，我们将回答 以下问题：1)嗅觉皮层回路整合味觉和 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的反应 清醒成年大鼠皮层神经元对味觉-嗅觉混合物及其单感成分的反应；2)如何 由特定味道的经验塑造的嗅觉皮层回路执行的多感官操作？ 为了解决这个问题，我们将实验性地操纵老鼠对特定味觉-嗅觉混合物的体验，并记录 嗅皮层神经元群对一致、不一致和未暴露的味觉的反应 混合物及其单一感觉成分；以及3)整合跨模式输入的能力如何 在整个生命周期内发育吗？为了解决这个问题，我们将跟踪嗅觉的单模式和跨模式反应 清醒大鼠在出生后早期发育的不同阶段的皮质；成功地实现这些 目标，我们独特的调查团队汇集了风味加工和清醒啮齿动物方面的专业知识 嗅皮层生理学(Pi Maier)，多感觉相互作用的计算基础(Co-I Rowland)，以及 多感官系统的发展(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).