中文摘要
果蠅在經過一個循環的氣味-電擊連結學習後，只能形成無法超過一天的不穩定記憶。若要形成穩定的長期嗅覺嫌惡記憶，則需要多次循環的連結訓練以及新的蛋白質合成。有趣的是，當我們抑制果蠅的學習記憶中樞-蕈狀體中新的蛋白質合成時，長期記憶卻不會受到損害。因此，我們想了解在學習之後，蕈狀體中是否有新的蛋白質合成，若是有，這些新合成蛋白質的功能是甚麼? 藉由專一地在蕈狀體中表達對溫度敏感的核醣體去活化毒素，我們發現：一、在訓練後抑制蕈狀體中的蛋白質合成會使得三小時的記憶分數增加。二、增加的記憶具有抗昏迷的特性，但是卻不會受到會使依賴radish的抗昏迷記憶受損的血清素合成抑制劑影響。三、增加的記憶是由昏迷敏感的記憶衍生而來的，卻可以維持一天以上。根據這些發現，我們認為訓練後蕈狀體中新合成蛋白質的主要功能是阻止未成熟的記憶固化成可維持長期的穩定記憶，而抑制訓練後蕈狀體中的蛋白質合成則促使僅經過一個循環訓練後生成的不穩定記憶提早固化為具抗昏迷特性的長期穩定記憶。

Abstract
In Drosophila, a single training session of odor-shock association can only produce labile form memory which cannot last over one day. To form aversive long-term memory (LTM), multiple training sessions and de novo protein synthesis are required. Interestingly, inhibiting de novo protein synthesis in mushroom body (MB), a well-known neuroanatomical site involved in learning and memory, does not impair LTM. Here, we ask whether there is de novo protein synthesis in MB after training, and if so, what is the function of these proteins? By specifically expressing a temperature-sensitive ribosome-inactivating toxin in MB, we found that (i) inhibition of MB protein-synthesis after training enhances three-hour memory retention score. (ii) The enhanced memory is resistant to anesthesia but insensitive to serotonin synthesis inhibition which impairs radish-dependent anesthesia-resistant memory (ARM). (iii) The enhanced memory is derived from anesthesia-sensitive memory but is able to last over one day. Based on these findings, we propose that the main function of post-training-synthesized proteins in MB is to prevent premature memory from consolidating into long-lasting form, and inhibition of MB protein-synthesis after training allows early-consolidation of labile memory into anesthesia-resistant, long-lasting memory after only one single session of training.

Table of Contents
中文摘要----------------------------------------------------------------------------1
Abstract -----------------------------------------------------------------------------2
1. Introduction -------------------------------------------------------------------3
2. Materials and Methods ------------------------------------------------------6
　　3. Results -------------------------------------------------------------------------9
4. Discussion --------------------------------------------------------------------12
5. Figures-------------------------------------------------------------------------15
6. Appendix Figures ------------------------------------------------------------21
7. References --------------------------------------------------------------------24

7. References
1. Tully, T., and Quinn, W. (1985). Classical conditioning and retention in normal and mutant Drosophila melanogaster. Journal of Comparative Physiology 157, 263-277.
2. Tully, T., Preat, T., Boynton, S.C., and Del Vecchio, M. (1994). Genetic dissection of consolidated memory in Drosophila. Cell 79, 35-47.
3. Folkers, E., Drain, P., and Quinn, W.G. (1993). Radish, a Drosophila mutant deficient in consolidated memory. Proceedings of the National Academy of Sciences of the United States of America 90, 8123-8127.
4. Endo, Y., Mitsui, K., Motizuki, M., and Tsurugi, K. (1987). The mechanism of action of ricin and related toxic lectins on eukaryotic ribosomes. The site and the characteristics of the modification in 28 S ribosomal RNA caused by the toxins. Journal of Biological Chemistry 262, 5908-5912.
5. Endo, Y., and Tsurugi, K. (1987). RNA N-glycosidase activity of ricin A-chain. Mechanism of action of the toxic lectin ricin on eukaryotic ribosomes. Journal of Biological Chemistry 262, 8128-8130.
6. Chen, C.C., Wu, J.K., Lin, H.W., Pai, T.P., Fu, T.F., Wu, C.L., Tully, T., and Chiang, A.S. (2012). Visualizing long-term memory formation in two neurons of the Drosophila brain. Science 335, 678-685.
7. Lee, P.T., Lin, H.W., Chang, Y.H., Fu, T.F., Dubnau, J., Hirsh, J., Lee, T., and Chiang, A.S. (2011). Serotonin-mushroom body circuit modulating the formation of anesthesia-resistant memory in Drosophila. Proceedings of the National Academy of Sciences of the United States of America 108, 13794-13799.
8. Mao, Z., Roman, G., Zong, L., and Davis, R.L. (2004). Pharmacogenetic rescue in time and space of the rutabaga memory impairment by using Gene-Switch. Proceedings of the National Academy of Sciences of the United States of America 101, 198-203.
9. Quinn, W.G., and Dudai, Y. (1976). Memory phases in Drosophila. Nature 262, 576-577.
10. Margulies, C., Tully, T., and Dubnau, J. (2005). Deconstructing memory in Drosophila. Current Biology 15, R700-R713.
11. Shuai, Y., Lu, B., Hu, Y., Wang, L., Sun, K., and Zhong, Y. (2010). Forgetting is regulated through Rac activity in Drosophila. Cell 140, 579-589.
12. Plaçais, P.-Y., and Preat, T. (2013). To favor survival under food shortage, the brain disables costly memory. Science 339, 440-442.