Department of Psychology and Program in Neuroscience, Florida State University, Tallahassee, Florida 32311, USA.
J Neurosci. 2012 Jul 18;32(29):10086-92. doi: 10.1523/JNEUROSCI.6036-11.2012.
Several methods exist for reliably determining the motivational valence of a taste stimulus in animals, but few to determine its perceptual quality independent of its apparent affective properties. Individual differences in taste preference and acceptability could result from variance in the perceptual qualities of the stimulus leading to different hedonic evaluations. Alternatively, taste perception might be identical across subjects, but the processing of the sensory signals in reward circuits could differ. Using an operant-based taste cue discrimination/generalization task involving a gustometer, we trained male Long-Evans rats to report the degree to which a test stimulus resembled the taste quality of either sucrose or quinine regardless of its intensity. The rats, grouped by a characteristic bimodal phenotypic difference in their preference for sucralose, treated this artificial sweetener as qualitatively different-compared to sucralose-avoiding rats, the sucralose-preferring rats found the stimulus much more perceptually similar to sucrose. Although the possibility that stimulus palatability may have served as a discriminative cue cannot entirely be ruled out, the profile of results suggests otherwise. Subsequent brief-access licking tests revealed that affective licking responses of the same sucralose-avoiding and -preferring rats differed across concentration in a manner approximately similar to that found in the stimulus generalization task. Thus, the perceived taste quality of sucralose alone may be sufficient to drive the observed behavioral avoidance of the compound. By virtue of its potential ability to dissociate the sensory and motivational consequences of a given experimental manipulation on taste-related behavior, this approach could be interpretively valuable.
有几种方法可以可靠地确定动物的味觉刺激的动机效价,但很少有方法可以确定其感知质量而不考虑其明显的情感属性。味觉偏好和可接受性的个体差异可能是由于刺激的感知质量的差异导致不同的愉悦评价。或者,味觉感知可能在不同的个体中是相同的,但是在奖励回路中对感觉信号的处理可能不同。使用涉及味觉计的基于操作的味觉线索辨别/概括任务,我们训练雄性长耳大鼠报告测试刺激与蔗糖或奎宁的味觉质量相似的程度,无论其强度如何。这些大鼠根据其对三氯蔗糖的偏好表现出特征性的双峰表型差异进行分组,与避免三氯蔗糖的大鼠相比,它们将这种人工甜味剂视为与三氯蔗糖不同的物质,与蔗糖相比,喜欢三氯蔗糖的大鼠发现刺激更具感知相似性。虽然不能完全排除刺激的美味可能作为辨别线索的可能性,但结果的概况表明并非如此。随后的短暂舔舐测试表明,同样避免三氯蔗糖和喜欢三氯蔗糖的大鼠的舔舐反应在情感上因浓度而异,这与刺激概括任务中发现的方式大致相似。因此,三氯蔗糖的感知味觉质量本身可能足以导致对该化合物的观察到的行为回避。由于其能够将与味觉相关的行为的给定实验操作的感官和动机后果分开,因此这种方法可能具有解释价值。