Dept. Behavioural Biology, Bielefeld University, PO Box 100131, 33501 Bielefeld, Germany.
Neurobiol Learn Mem. 2010 Mar;93(3):322-9. doi: 10.1016/j.nlm.2009.11.006. Epub 2009 Nov 26.
Zebra finches (Taeniopygia guttata) are able to learn the position of food by orienting on spatial cues in a 'dry water maze'. In the course of spatial learning, the hippocampus shows high expression of the immediate early genes (IEGs) Zenk and c-Fos, indicating high activation of this area during learning. In contrast, the IEG activity is nearly absent if the birds do not have to rely on spatial cues. In the present experiment it was investigated whether hippocampal activation can also be observed if the learned spatial task is recalled. For this purpose, the hippocampal Zenk and c-Fos activation of birds in an early learning stage was compared with that of others having well reached their maximal performance. The results show that the avian hippocampus is also active during recall of a learned spatial task, but the activation is significantly lower than in animals learning actually. As in previous experiments, hippocampal IEG expression showed strong variation not only in the position of the active patches of neurons, but also in size and cell density. The observed difference contributes to the view that immediate early genes may not be indicators of activation alone, but may be due to a combination of activation and plastic changes.
斑马雀（Taeniopygia guttata）能够通过在“干水迷宫”中定向空间线索来学习食物的位置。在空间学习过程中，海马体表现出即时早期基因（IEGs）Zenk 和 c-Fos 的高表达，表明该区域在学习过程中高度活跃。相比之下，如果鸟类不必依赖空间线索，IEG 活性几乎不存在。在本实验中，研究了如果回忆起所学的空间任务，是否也可以观察到海马体的激活。为此，比较了早期学习阶段鸟类的海马 Zenk 和 c-Fos 激活与已经达到最佳表现的鸟类的激活。结果表明，鸟类的海马体在回忆已学过的空间任务时也很活跃，但激活程度明显低于正在学习的动物。与以前的实验一样，海马体 IEG 表达不仅在神经元活跃斑块的位置上表现出强烈的变化，而且在大小和细胞密度上也表现出强烈的变化。观察到的差异表明，即时早期基因可能不仅仅是激活的指标，而是可能由于激活和可塑性变化的结合。
