Ramirez I
Monell Chemical Senses Center, Philadelphia, PA 19104-3308, USA.
Physiol Behav. 1996 Aug;60(2):595-610. doi: 10.1016/s0031-9384(96)80037-0.
Infusing rats with 6% carbohydrate whenever they drank a test fluid stimulated their intake of 0.03-0.3% saccharin, 0.9% sodium chloride, and 0.5% oligosaccharide solutions within 1 to 3 days, but did not greatly increase intake of cherry-flavored water, 2% saccharin, 0.45% sodium chloride, monosodium glutamate, 0.025% sucrose octaacetate, or 0.4% maltodextrin, when food was available adlib. In general, it was more difficult to detect an effect with aversive stimuli, but it was possible to detect a significant effect with one such aversive flavor by either increasing the number of animals to permit detection of a small effect, or by using a preference test. For most stimuli, however, rats that had been trained with food available and then tested when food deprived showed significant increases in fluid intake, compared to rats that had been given the same flavor without carbohydrate infusions, even when plain water was infused in all rats during the food deprivation test. The following forms of evidence indicate that the increased intake is due to a form of Pavlovian conditioning. It tends to increase over repeated trials and to persist for a day after the carbohydrate infusions have been discontinued. Indeed, in one experiment, increased intake even persisted for a day when the infusion conditions were reversed, such that control rats were infused with carbohydrate and experimental rats were infused with water. Increased ingestion is attenuated by preexposure to the infusion in the absence of an appropriate taste solution. Increased ingestion is attenuated by preexposure to the taste solution in the absence of infusions (i.e., latent inhibition). Although increased intake is a form of associative conditioning, it is unlike malaise-conditioned taste aversions because taste aversions were conditioned to monosodium glutamate, cherry flavor, and saccharin with equal ease. The ease with which infusion increased intake is influenced by at least three different factors, degree of aversiveness, stimulus intensity, and rats' innate predisposition to acquire certain stimulus-response relationships more readily than others.
每当大鼠饮用测试液时给它们输注6%的碳水化合物，在1至3天内会刺激它们摄入0.03 - 0.3%的糖精、0.9%的氯化钠和0.5%的低聚糖溶液，但在自由进食时，并不会大幅增加它们对樱桃味水、2%糖精、0.45%氯化钠、味精、0.025%蔗糖八乙酸酯或0.4%麦芽糊精的摄入量。一般来说，用厌恶刺激检测效果更困难，但通过增加动物数量以检测小的效果，或者使用偏好测试，有可能检测到一种这样的厌恶味道的显著效果。然而，对于大多数刺激物，与未进行碳水化合物输注而给予相同味道的大鼠相比，在自由进食时接受训练然后在食物剥夺时进行测试的大鼠，即使在食物剥夺测试期间所有大鼠都输注了清水，其液体摄入量也显著增加。以下形式的证据表明摄入量的增加是由于一种巴甫洛夫式条件作用。它往往会在重复试验中增加，并在碳水化合物输注停止后持续一天。事实上，在一项实验中，当输注条件颠倒时，即对照大鼠输注碳水化合物而实验大鼠输注水，摄入量的增加甚至持续了一天。在没有合适的味觉溶液的情况下预先接触输注会减弱摄入量的增加。在没有输注的情况下预先接触味觉溶液（即潜伏抑制）会减弱摄入量的增加。虽然摄入量的增加是一种联想性条件作用，但它与不适条件性味觉厌恶不同，因为味觉厌恶对味精、樱桃味和糖精的形成同样容易。输注增加摄入量的容易程度至少受三个不同因素影响，厌恶程度、刺激强度以及大鼠天生更容易获得某些刺激 - 反应关系的倾向。
