GUSTATORY AVERSIONS AND THE PARABRACHIAL NUCLEUS

描述：研究者声称， 味觉刺激是一个复杂的三个过程之间的相互作用， 新恐惧症，定义为对新口味的先天恐惧，胃肠道 不适，一种正常现象，发生在摄入 有毒物质，和学习，味觉之间的联想联系 和不适研究者选择了条件性味觉厌恶 (CTA)范式作为一个模型，现在提出调查的作用， 臂旁核（PBN）在CTA学习中的作用。PBN在战略上 在这个反应中很重要，因为它似乎是这两个问题的一部分。 通过脑干的上行和下行通路， 味觉和内脏传入系统。在以前的工作中， 研究人员复制和扩展了其他人的工作，表明 PBN病变破坏动物形成CTA的能力。重要的是他 还发现PBN病变似乎消除了味觉新恐惧症， 他认为，非新恐惧症动物不能形成CTA， 他们不认为新奇的口味有潜在的危险。因此他 假设PBN损伤的大鼠明显不能形成一个 CTA，而不是由于无法形成联想 味觉和有害事件之间的联系，实际上是由于 损伤引起的对促味剂的错误感知。在这方面， 建立了完整的动物不容易形成CTA以及熟悉 (i.e.,已知是安全的）促味剂。 拟议的实验将使用鹅膏蕈氨酸病变的选定地区， PBN来测试这个假设的各个方面。在一系列的 在实验中，将评估具有PBN病变的动物的新恐惧症， 包括几种促味剂在内的多种刺激物， 这种动物会有普遍的恐新症非 除了几种味剂之外，还将使用味觉刺激。换句 在实验中，PBNx动物感知味剂的能力将是 评估，以及他们适当反应的能力（即，到 表现出对促味剂的“警戒反应”）。 在另一系列 在实验中，PBN病变的动物将受到更多的 严格和更长的协议，开发CTA， 假设是，同样的努力将需要形成一个 在PBNx大鼠中厌恶一种新的促味剂，这是形成 对控制中熟悉的促味剂的厌恶。最后，调查员 受试者对不同味剂的相对熟悉程度 在试图条件厌恶，以最大限度地或 最小化PBNx和对照动物之间的差异。 在所有提出的实验和范例中，将有一个 评估两个主要司的相对贡献 PBN。内侧PBN是味觉部分，外侧PBN是味觉部分。 内脏传入部分因此，所有的实验都将在 同时，一只手臂研究内侧，另一只手臂研究内侧， 外侧PBN。对于大多数情况，研究者还将包括 两种急性（即， 15分钟）和24小时摄入量， 评估短期味觉和摄食后的影响。 在试点工作中，调查人员证明， 内侧PBNx大鼠的新恐惧症，以及它们（尽管减弱） 形成CTA。他还复制了其他人的影响， PBN的电解损伤，并获得了与 局部应用鹅膏蕈氨酸。他还提供了PBNx大鼠 可以区分促味剂，并且它们经历急性毒性， 氯化锂的影响。

DESCRIPTION: The investigator asserts that the ingestive reaction to taste stimuli is a complex interaction among three processes, taste neophobia, defined as an innate fear of novel tastes, gastrointestinal malaise, a normal phenomenon that occurs following ingestion of poisonous substances, and learning, the associative link between taste and malaise. The investigator has chosen the conditioned taste aversion (CTA) paradigm as a model and now proposes to investigate the role of the parabrachial nuclei (PBN) in CTA learning. The PBN is strategically important in this response because it appears to be part of both the ascending and the descending pathways through the brainstem involved in the gustatory and visceral afferent systems. In previous work, the investigator has replicated and extended the work of others showing that PBN lesions disrupt the ability of animals to form CTAs. Importantly, he has also found that PBN lesions appear to abolish taste neophobia, and he argues that non-neophobic animals are not able to form CTAs because they do not perceive novel tastes as potentially dangerous. He therefore hypothesizes that the apparent inability of PBN-lesioned rats to form a CTA, rather than being due to an inability to form associative connections between tastes and noxious events, is actually due to a lesion-induced misperception of the tastant. In this regard, it is well established that intact animals do not easily form CTAs well to familiar (i.e., known to be safe) tastants. Proposed experiments will use ibotenic acid lesions of selected areas of the PBN to test various aspects of this hypothesis. In one series of experiments, animals with PBN lesions will be assessed for neophobia to a variety of stimuli including several tastants, the hypothesis being that such animals will have a generalized neophobic deficit. Non- gustatory stimuli will be used in addition to several tastants. In other experiments, the ability of PBNx animals to perceive tastants will be assessed, as will their ability to react appropriately (i.e., to demonstrate an "alerting response") to the tastants. In another series of experiments, animals with PBN lesions will be subjected to more rigorous and more prolonged protocols for developing CTAs, the hypothesis being that the same effort will be required to form an aversion to a novel tastant in PBNx rats as is normally required to form an aversion to a familiar tastant in controls. Finally, the investigator will vary the relative familiarity of the subjects to various tastants prior to attempting to condition aversions in order to maximize or minimize the differences between PBNx and control animals. In all of the proposed experiments and paradigms, there will be an assessment of the relative contributions of the two major divisions of the PBN. The medial PBN is the gustatory portion and the lateral PBN is the visceral afferent portion. Therefore, all experiments will be run in parallel, with one arm investigating the medial and the other the lateral PBN. For most conditions the investigator will also include assessments of both acute (i.e., 15-minute) and 24-hour intakes to assess both short-term gustatory and post-ingestive influences. In pilot work, the investigator has demonstrated both the lack of neophobia in medial PBNx rats, and their (albeit lessened) ability to form a CTA. He has also replicated the effects of others with electrolytic lesions of the PBN and obtained comparable findings with locally applied ibotenic acid. He has also provided data that PBNx rats can discriminate tastants, and that they experience the acute toxic effects of lithium chloride.