The Environmental Control of Ingestion: The Roles of Associations and Signals

当一种特殊风味的食物或饮料引起肠胃不适时，类似风味的食物随后就会被避免。这种现象通常被称为“品味厌恶学习”。厌恶味道的学习发生在各种物种中，包括人类、非人类灵长类动物、啮齿动物和鸟类。这种学问的特点在于它的力量。例如，一种味道与疾病的配对通常足以形成对味道的持久厌恶，而当味道与疾病分开几分钟甚至几小时时，通常可以形成实质性的厌恶。贝斯特博士的实验研究了厌恶味道的学习与它发生的环境背景之间的关系。例如，他发现，在发生了味觉厌恶条件反射的环境中，老鼠不会喝它们熟悉的液体——它们在其他情况下很容易喝的液体。这表明环境和独特的味道与疾病有关。此外，贝斯特博士还发现，环境背景可以提供一些信息，告诉我们在不将环境本身与疾病联系起来的情况下，在哪些地方应该避免某种独特的味道。也就是说，在一种环境中测试的食物与疾病有关，但在另一种“安全”环境中食用的食物只有在“危险”的情况下才会被避免。此外，在这个过程中，在危险的背景下唯一避免的味道是与疾病相伴的味道。这表明，根据具体情况，环境可以与摄入的不良后果联系在一起，也可以简单地指示应该避免某种味道的位置。贝斯特博士新实验的主要重点是确定区分这两种现象的因素。这两种现象以及产生它们的过程都对人类健康产生重大影响。了解这些基本调节过程的作用，将有助于了解化疗和放疗对癌症患者的一些副作用。这些人中的许多人对这种治疗方案感到恶心，随后对治疗进行的环境产生厌恶。贝斯特博士的研究既可以阐明这些环境厌恶背后的过程，也可以为减少它们的发生提供替代方案。

When a disinctively flavored food or drink is followed by gastrointestinal distress, similarly flavored edibles are subsequently avoided. This phenomenon is generally known as taste-aversion learning. Taste-aversion learning occurs in a variety of species, including humans, nonhuman primates, rodents, and birds. Such learning is distinguished by its strength. For example, one pairing of a taste with illness is often sufficient to condition a lasting aversion to the taste, and substantial aversions usually can be conditioned when the taste and illness are separated by minutes or even hours. Dr. Best's experiments investigate how taste-aversion learning is related to the environmental context in which it occurs. He has found, for example, that rats will not drink familiar fluids-- fluids they would readily consume in other contexts--in an environment in which taste-aversion conditioning has occurred. This indicates that environments as well as distinctive flavors become associated with illness. In addition, Dr. Best has found that an environmental context can provide information about where a distinctive taste should be avoided without the context itself being associated with illness. That is, edibles tested in one environment correlated with illness but also consumed in another "safe" environment will be avoided only in the "dangerous" context. Moreover, in this procedure the only taste avoided in the dangerous context is the one paired with illness there. This indicates that, depending on the circumstances, environments can be associated with the aversive consequences of ingestion or simply signal the location in which a taste should be avoided. The primary focus of Dr. Best's new experiments is to determine the factors distinguishing these two phenomena. Both of these phenomena, as well as the processes producing them, have significant implications for human health. Understanding the role of the basic conditioning processes underlying each should provide insight into some side effects of chemo- and radio-therapy in cancer patients. Many of these people become nauseous from such therapy regimens and subsequently develop aversions to the environments in which the treatments took place. Dr. Best's research can both elucidate the processes underlying these environmental aversions and provide alternatives for reducing their occurrence.