Pecoraro Norman, Dallman Mary F
Department of Physiology, University of California, San Francisco, CA 94143-0444, USA.
Behav Neurosci. 2005 Apr;119(2):366-87. doi: 10.1037/0735-7044.119.2.366.
Rats were used in a successive negative contrast procedure to determine which brain structures were activated by sucrose concentration downshifts, and on what day this occurred. Subjects were given preshift solutions for 12 days before being shifted to their postshift concentrations. Groups included 2 unshifted controls (32%-32% and 4%-4%) and 1 shifted group (32%-4%). Half of each group was killed 1 hr after the first exposure to the shifted solution (Shift 1), and half after the second exposure (Shift 2). Brains were processed for c-Fos-like immunoreactivity (FLI). Two major patterns emerged. Terminal drinking of 32% sucrose activated minimal brainstem regions involved in palatable taste, visceral feedback, and fluid homeostasis. In contrast, shifted subjects showed extensive cortical activation with selective activation in cerebral nuclei and brainstem. Robust FLI on Shift 1 was absent on Shift 2, consistent with evidence for rapid (1-trial) changes in all major motor outputs mediated by expectancy.
在连续负性对比实验中使用大鼠，以确定哪些脑结构会因蔗糖浓度下降而被激活，以及这一现象发生在哪一天。在将实验对象转移到转移后浓度之前，先给予它们12天的转移前溶液。实验组包括2个未转移对照组（32%-32%和4%-4%）和1个转移组（32%-4%）。每组的一半在首次接触转移后溶液1小时后处死（转移1），另一半在第二次接触后处死（转移2）。对大脑进行c-Fos样免疫反应（FLI）处理。出现了两种主要模式。饮用32%蔗糖的末期激活了参与美味味觉、内脏反馈和液体平衡的最小脑干区域。相比之下，转移组的实验对象表现出广泛的皮层激活，并在脑核和脑干中有选择性激活。转移1时的强烈FLI在转移2时消失，这与预期介导的所有主要运动输出快速（单次试验）变化的证据一致。
