Department of Neural and Behavioral Sciences, College of Medicine, The Pennsylvania State University, Hershey, PA 17033, USA.
Physiol Behav. 2012 Jan 18;105(2):576-88. doi: 10.1016/j.physbeh.2011.06.010. Epub 2011 Jun 16.
The reward strength of orosensory sucrose and corn oil was measured using fixed and progressive ratio operant schedules. Because the orosensory effects of the stimuli were of interest, Experiment 1 compared operant responses for sucrose in sham and real feeding rats. The results demonstrated that rats would work for sucrose solutions without the accompanying postingestive effects. Furthermore, the break points for high concentrations of sucrose (1.0 M or 2.0 M) were significantly higher in sham feeding rats than in real feeding controls. Experiment 2 investigated the role of the parabrachial nucleus (PBN) and of the thalamic orosensory area (TOA) in sucrose and corn oil reward. During free access, rats with PBN lesions (PBNx) licked significantly less sucrose solution than their controls, but both groups ingested a similar volume of corn oil emulsion. When an operant was imposed, these same PBNx rats failed to respond for sucrose and continued only modestly for corn oil. In contrast, the TOA lesioned rats (TOAx) showed no impairment in responding for sucrose or corn oil during either the free access or operant sessions. Furthermore, rats with TOA lesions demonstrated significantly higher break points for sucrose than did their controls. Together, the data imply that the PBN but not the TOA is critical for the perception of, or responding to the reward value of sucrose and corn oil.
使用固定比率和渐进比率操作条件反射程序来测量味觉蔗糖和玉米油的奖赏强度。由于刺激的味觉效应是研究的重点，实验 1 比较了假饲和真饲大鼠对蔗糖的操作反应。结果表明，大鼠可以为没有伴随的摄入后效应的蔗糖溶液工作。此外，在假饲大鼠中，高浓度蔗糖（1.0 M 或 2.0 M）的断点明显高于真饲对照组。实验 2 研究了臂旁核（PBN）和丘脑味觉区（TOA）在蔗糖和玉米油奖赏中的作用。在自由摄取期间，PBN 损伤（PBNx）大鼠舔食的蔗糖溶液明显少于对照组，但两组大鼠摄入的玉米油乳剂体积相似。当施加操作条件时，这些相同的 PBNx 大鼠不再对蔗糖做出反应，只是适度地对玉米油做出反应。相比之下，TOA 损伤（TOAx）大鼠在自由摄取或操作期间对蔗糖或玉米油的反应均未受损。此外，与对照组相比，TOA 损伤大鼠的蔗糖断点明显升高。总之，这些数据表明 PBN 而不是 TOA 对蔗糖和玉米油的感知或对其奖赏价值的反应至关重要。
