生物體活動都會受到生物鐘的影響,，蟑螂也不例外,。美國科學家近日研究發(fā)現(xiàn)，蟑螂的學習能力在早晚相差巨大,。這是首例獲得證實的關于昆蟲學習能力會受到生物鐘影響的研究報告,，無疑將對人們深入研究生物鐘的作用產(chǎn)生幫助,。相關論文9月24日在線發(fā)表于《美國國家科學院院刊》（PNAS）上。
領導該項研究的是美國范德比爾特大學的生物學家Terry L. Page,。他和研究小組訓練蟑螂將它們討厭的薄荷油味和喜歡的香草味聯(lián)系起來，并在一天24小時內(nèi)不同的時間段進行訓練,，以測試它們能記住這種聯(lián)系的時間長度,。結果發(fā)現(xiàn)，在傍晚訓練,，蟑螂能記住這種聯(lián)系數(shù)天,；在夜間訓練，效果也不錯,；而在早晨訓練,，蟑螂根本就不能形成新的記憶,。
Page說，早晨造成的缺陷如此顯著,，真是讓人非常吃驚,。那么蟑螂為什么不愿意在這個時間段學習新東西？Page表示目前尚無準確答案,。
之前關于生物鐘的研究關注的大多都是視覺系統(tǒng)，此次研究則有很大不同,。Page表示,，此次研究包括了嗅覺系統(tǒng),，這表明生物鐘會影響為數(shù)眾多的感覺器官。
此次實驗有助于人們對生物鐘和記憶,、學習等之間的聯(lián)系展開更深入的研究,。Page說：“此次研究表明,，至少從某些情況來說,，一天之中特定的時刻具有深遠的影響,。通過研究生物鐘調(diào)節(jié)學習和記憶的方式，我們能夠更深入地了解這些過程發(fā)生的機制,，以及哪些因素能對它們產(chǎn)生影響。”（科學網(wǎng) 梅進/編譯）
原始出處:
Published online before print September 24, 2007
Proc. Natl. Acad. Sci. USA, 10.1073/pnas.0702082104
( biological rhythms | cockroach | differential conditioning | memory )
Susan Decker, Shannon McConnaughey, and Terry L. Page *
Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235
Edited by Leslie C. Griffith, Brandeis University, Waltham, MA, and accepted by the Editorial Board August 10, 2007 (received for review March 6, 2007)
Olfactory learning in insects has been used extensively for studies on the neurobiology, genetics, and molecular biology of learning and memory. We show here that the ability of the cockroach Leucophaea maderae to acquire olfactory memories is regulated by the circadian system. We investigated the effect of training and testing at different circadian phases on performance in an odor-discrimination test administered 30 min after training (short-term memory) or 48 h after training (long-term memory). When odor preference was tested by allowing animals to choose between two odors (peppermint and vanilla), untrained cockroaches showed a clear preference for vanilla at all circadian phases, indicating that there was no circadian modulation of initial odor preference or ability to discriminate between odors. After differential conditioning, in which peppermint odor was associated with a positive unconditioned stimulus of sucrose solution and vanilla odor was associated with a negative unconditioned stimulus of saline solution, cockroaches conditioned in the early subjective night showed a strong preference for peppermint and retained the memory for at least 2 days. Animals trained and tested at other circadian phases showed significant deficits in performance for both short- and long-term memory. Performance depended on the circadian time (CT) of training, not the CT of testing, and results indicate that memory acquisition rather than retention or recall is modulated by the circadian system. The data suggest that the circadian system can have profound effects on olfactory learning in insects.
全文下載：Circadian regulation of insect olfactory learning
