Abstract

The ventral pallidum (VP) is an important structure in processing reward. The VP may be the only brain structure where localized lesions in rats replace normal facial “liking” expressions to sweetness with excessive “disgust” reactions, such as gapes and chin rubs, that are normally reserved for unpalatable tastes. The posterior half of the VP (pVP) contains a hedonic hot spot where opioid or related neurochemical stimulations can amplify positive “liking” reactions to sweet taste. This is the same site where lesions or pharmacological inactivations replace positive hedonic reactions to sucrose with intense negative “disgust.” In the present study, we aimed to identify brain networks recruited by pVP inactivation to generate excessive “disgust,” using neuronal Fos expression as a marker of neurobiological activation. Microinjections in pVP of inhibitory GABA_A/B agonists (muscimol and baclofen) caused rats to exhibit excessive “disgust” reactions to sucrose. Excessive “disgust” was accompanied by recruitment of neural Fos activation in several subcortical structures, including the posterior medial shell of nucleus accumbens (which also contains another GABAergic “disgust”-inducing “hedonic cold spot”), the bed nucleus of stria terminalis, lateral habenula, hypothalamus, and midbrain ventral tegmentum. Fos suppression was found in cortical limbic regions, including previously identified hedonic hot spots in the anteromedial orbitofrontal cortex and posterior insula. Finally, in addition to inducing excessive “disgust,” pVP inactivation abolished motivational “wanting” to eat palatable food, reduced positive social interactions, and reordered sensorimotor relations. Our findings identify potential “disgust” generators in the brain that are released into excitation by pVP inhibition and may serve as targets for future research.

中文翻译：

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绘制大脑中过多的“恶心”图：腹苍白质失活会募集分布式电路，使甜味“恶心”。

摘要

腹侧苍白球（VP）是奖励过程中的重要结构。VP可能是唯一的大脑结构，其中大鼠的局部病变会通过过度的“恶心”反应（例如缝隙和下巴摩擦）将正常的面部“喜欢”表达替换为甜味，这些反应通常保留给难吃的味道。VP（pVP）的后半部分含有享乐性热点，阿片类药物或相关的神经化学刺激可在其中刺激对甜味的积极“喜欢”反应。在同一部位，病变或药理学失活会以强烈的负面“厌恶”取代对蔗糖的阳性享乐反应。在本研究中，我们旨在使用神经元Fos表达作为神经生物学激活的标志物，鉴定通过pVP失活招募的大脑网络，以产生过多的“厌恶感”。_{A / B}激动剂（麝香酚和巴氯芬）使大鼠对蔗糖表现出过度的“厌恶”反应。过度的“厌恶”伴随着在几个皮层下结构中神经Fos的募集，包括伏伏核的后内侧壳（也包含另一个GABA能的“厌恶”诱导的“享乐性冷点”），纹状体终末床核外侧ha，下丘脑和中脑腹盖。在皮质边缘区域发现了Fos抑制，包括先前在眶前额叶皮层和后岛中发现的享乐性热点。最后，除了引起过度的“厌恶”之外，pVP的失活还消除了动机性的“想要”去吃可口的食物，减少了积极的社会互动，并重新排列了感觉运动关系。