Molecular neurobiology of olfactory learning in the land slug

我们研究了个人计算机是否对嗅觉学习是必要的。在第一系列实验中，在双侧PC消融7天后，平均通过将植物气味与奎尼丁配对来调节鼻涕虫。与假手术的弹头相比，有PC损伤的弹头显示出显著的学习得分较低。在第二系列实验中，首先对鼻涕虫进行条件处理，然后在不同的时间点对PC进行消融。当在PC损伤后3天进行测试时，这些鼻涕虫也显示出严重的记忆障碍。这些结果表明，PC至少对厌恶气味记忆的保持或提取是必要的。然后，我们研究了鼻涕虫中的中央突触是否显示出突触可塑性。单次电刺激触角神经在前脑(PC)诱发一个至少有3个成分的电位，该刺激被用作测试刺激。高频刺激触角神经后，诱发电位的正向成分增加，这种增强作用持续两个多小时。在PC中发现的突触可塑性可能与嗅觉学习有关。我们还筛选了大脑中因神经活动而上调的基因。解剖大脑会导致神经活动的一过性上调，这会诱导几个基因的转录。利用72对引物进行差异显示分析，共扩增出约10,000条条带，其中28条出现了表达水平的重复性变化，其中10条被克隆用于进一步分析。

We examined whether the PC is necessary for olfactory learning. In the first series of experiments, slugs were aversively conditioned by pairing vegetable odor with quinidine 7 days after ablation of bilateral PCs. The slugs with PC lesions showed significantly lower scores of learning compared to sham-operated slugs. In the second series of experiments, slugs were first conditioned, and at various time points, the PCs were ablated. When tested 3 days after PC lesion, these slugs also showed severe impairment of memory. These results indicate that the PC is necessary at least for the retention or retrieval of aversive odor memories.We then investigated whether the central synapses in the slug display synaptic plasticity. A single electrical stimulation of the tentacle nerve evoked a potential in the procerebrum (PC) with at least 3 components, and this stimulus was used as the test stimulus. After a high frequency stimulation of the tentacle nerve, the positive component of the evoked potential increased, and this potentiation lasted for more than two hours. That synaptic plasticity found in the PC may be involved in olfactory learning. We also screened genes in the brain that are upregulated by neural activity. Dissecting the brain results in transient up-regulation of neural activity, and this induces transcription of several genes. By differential display analyses using 72 pairs of primers, approximately 10,000 bands were displayed and 28 showed reproducible changes in the expression levels, and 10 of these were cloned for further analysis.