Department of Psychology, Binghamton University, Binghamton NY, USA.
Front Integr Neurosci. 2012 May 31;6:27. doi: 10.3389/fnint.2012.00027. eCollection 2012.
Behavioral and electrophysiological studies suggest that rats can identify a taste stimulus with a single lick, in <200 ms. However, the conditions under which these conclusions were drawn varied widely across experiments. We designed a series of experiments to assess the effects of the number of licks of a tastant that are available, tastant concentration and prior learning experience on the speed with which a tastant can modify behavior. To accomplish this we tested exemplars of four basic taste qualities (quinine, 0.1 mM; NaCl, 100 mM; saccharin, 4 mM, or sucrose, 100 mM; citric acid, 10 mM) in rats that were conditioned to avoid quinine. Taste stimuli were available for one, two, or three licks on separate days. All tastants were presented in a randomized order interspersed with water rinse licks presented on a variable ratio schedule. A tastant-specific significant increase in the proportion of long pauses in licking following quinine presentation was defined as evidence of "behavioral identification." Rats with aversion training given three licks of all taste stimuli paused significantly more often after quinine by the fourth interlick interval, ~580 ms. Control rats showed no evidence of quinine (0.1 mM) identification. When rats in all conditioning groups were tested with a high concentration of quinine (10 mM), a single lick was sufficient to produce significant pausing after quinine, but not until the fourth interlick interval, i.e., ~580 ms. Testing rats with only two tastants rather than four in a session had no effect on the speed of quinine identification. Present data confirm that a single lick is sufficient for rats to identify a taste stimulus, but that additional licks occur before evidence of identification is apparent. Furthermore, learning, tastant concentration and motivation to drink can all modify the speed of behavioral identification.
行为和电生理研究表明，老鼠可以在<200 毫秒内通过单次舔舐识别一种味觉刺激。然而，这些结论的得出条件在不同实验中差异很大。我们设计了一系列实验，以评估味觉刺激物的可舔次数、味觉刺激物浓度和先前的学习经验对味觉刺激物改变行为速度的影响。为此，我们测试了四种基本味觉（奎宁，0.1 mM；NaCl，100 mM；糖精，4 mM 或蔗糖，100 mM；柠檬酸，10 mM）的样本，这些味觉样本是在对奎宁有回避条件反射的老鼠身上进行测试的。味觉刺激物可在单独的日子里舔舐一次、两次或三次。所有味觉刺激物都以随机顺序呈现，中间穿插着用可变比率程序呈现的水冲洗舔舐。在奎宁呈现后，舔舐中长时间停顿的比例有特定的、显著的增加，被定义为“行为识别”的证据。在所有味觉刺激物上给予三次舔舐回避训练的老鼠，在第四次舔舐间隔（约 580 毫秒）后，在奎宁呈现后明显更频繁地停顿。对照老鼠没有表现出对奎宁（0.1 mM）的识别。当所有训练组的老鼠都用高浓度的奎宁（10 mM）进行测试时，单次舔舐足以在奎宁后产生显著的停顿，但直到第四个舔舐间隔（即约 580 毫秒）。在一次实验中，让老鼠只测试两种而不是四种味觉刺激物，不会影响奎宁识别的速度。现有数据证实，老鼠只需单次舔舐就能识别一种味觉刺激物，但在明显出现识别迹象之前，还需要进行额外的舔舐。此外，学习、味觉刺激物浓度和饮水动机都可以改变行为识别的速度。
