Richardson R, Paxinos G, Lee J
School of Psychology, Faculty of Life Sciences, University of New South Wales, Sydney, Australia.
Behav Neurosci. 2000 Dec;114(6):1167-73.
During development, conditioned responses usually occur first to olfactory, then to auditory, and finally to visual cues. The authors of the present study report that fear potentiation of startle to an olfactory conditioned stimulus emerges relatively late in development (i.e., at 23 days of age; Experiments 1 and 2). The failure to observe conditioned odor potentiation of startle (OPS) in younger rats was not due to a failure to either acquire or remember the odor-shock association (Experiment 3). Surprisingly, the authors also found that rats trained at 16 but tested at 23 days of age failed to exhibit the OPS effect even though they did exhibit pronounced odor avoidance (Experiment 4). The results are discussed in terms of (a) sensory-specific sequential emergence of learned fear, (b) the neural circuit involved in fear potentiation of startle, and (c) the concept that conditioned responding is appropriate to the animal's age at the time of training rather than its age at testing.
在发育过程中，条件反应通常首先出现在嗅觉方面，然后是听觉，最后是视觉线索。本研究的作者报告称，对嗅觉条件刺激的惊吓恐惧增强在发育过程中出现得相对较晚（即23日龄；实验1和2）。在较年幼的大鼠中未能观察到惊吓的条件性气味增强（OPS），并非由于未能习得或记住气味-电击关联（实验3）。令人惊讶的是，作者还发现，在16日龄接受训练但在23日龄进行测试的大鼠，即使表现出明显的气味回避，也未能表现出OPS效应（实验4）。研究结果从以下几个方面进行了讨论：（a）习得性恐惧的感官特异性顺序出现；（b）惊吓恐惧增强所涉及的神经回路；（c）条件反应与训练时动物年龄而非测试时动物年龄相适应的概念。
