Multimodal flavor integration and retronasal olfaction in the rat

描述（由申请人提供）：多模态刺激如何整合是神经科学的一个基本问题。这个问题与味觉感知特别相关，在摄入过程中，触觉、温度、味觉和嗅觉的同时刺激总是发生的。人类的功能成像研究为多模态风味整合的神经基础提供了重要的见解，但不能解决需要更高分辨率或神经活动或风味体验的实验操作的问题。为了解决这些限制，本项目的目标是建立一个大鼠模型来研究风味整合的神经机制。为了确定大鼠的鼻后嗅觉是否会像人类一样发生，第一项研究将采用光学钙成像来测量嗅球中与清醒大鼠口服气味剂相关的各种行为所引起的时空模式。复古和正鼻气味之间的感知相似性将同时进行研究。为了确定风味整合是否发生在大鼠的感知中，第二项研究将调查条件性气味厌恶是否会泛化到味觉，以及条件性味觉厌恶是否会泛化到嗅觉。它也将检查是否先前的气味-味觉对经验是必要的泛化发生，以及泛化的特异性是否遵循这种习得的味道-气味质量一致性。另一项单独的研究将调查味道经验依赖于味觉对气味厌恶和气味对味道厌恶的增强。为了确定嗅球中是否发生多感觉整合，第三项研究将评估口腔刺激是否以及如何调节清醒和急性大鼠的光学成像嗅球中的气味反应。通过调节风味体验建立的刺激质量一致性和风味整合的时间一致性的重要性也将被评估。总之，这些研究的目的是提供从根本上新的知识，关于使用大鼠模型的味道感知的神经机制。公共卫生相关性：本项目研究风味感知的神经基础。由于风味在刺激食物摄入中起着核心作用，因此研究风味感知的神经机制对于理解导致饮食相关疾病（如肥胖、糖尿病和心血管疾病）的感官因素至关重要。

Description (provided by applicant): How multimodal stimuli become integrated is a fundamental question in neuroscience. This question is particularly relevant to flavor perception, in which simultaneous stimulation of touch, temperature, taste and olfaction invariably occurs during ingestion. Functional imaging studies in humans have provided important insights into the neural bases of multimodal flavor integration, yet cannot address issues requiring higher resolution or experimental manipulation of neural activity or of flavor experience. To address these limitations, the goal of the present project is to establish a rat model for investigating the neural mechanisms of flavor integration. To determine whether retronasal olfaction occurs in rats as it does in humans, a first study will employ optical calcium imaging to measure spatio-temporal patterns evoked in the olfactory bulb by various behaviors associated with the oral ingestion of odorants by awake rats. The perceptual similarities between retro- and orthonasal odorants will simultaneously be investigated. To determine whether flavor integration occurs perceptually in rats, a second study will investigate whether conditioned odor aversions generalize to tastants, and whether conditioned taste aversions generalize to odorants. It will also be examined whether prior odor-taste pair experience is necessary for generalization to occur and whether the specificity of the generalization follows this learned taste-odor quality congruence. A separate study will investigate the flavor experience-dependence of the potentiation of an odor aversion by taste and of a taste aversion by odor. To determine whether multi-sensory integration occurs in the olfactory bulb, the third study will evaluate whether and how oral stimuli can modulate odor responses in the optically-imaged olfactory bulb of awake and acute rats. The importance of both stimulus quality congruence, as established by modulating flavor experience, and temporal congruence for flavor integration will also be assessed. Together these studies are intended to provide fundamentally new knowledge about the neural mechanisms of flavor perception using a rat model. PUBLIC HEALTH RELEVANCE: This project investigates the neural basis of flavor perception. Because flavor plays a central role in motivating food intake, research on the neural mechanisms of flavor perception is essential for understanding the sensory factors that contribute to eating-related disorders such as obesity, diabetes and cardiovascular disease.