睡眠對於記憶的處理扮演著重要的角色,然而在連續學習不同類型但具有共同神經表徵的記憶測試後睡眠結構的變化,以及第一種測試成功學習導致的記憶固化對於第二類測試的學習所造成的影響,仍尚未明瞭,故為本研究之目的。我們所使用的記憶測試包含雙向迴避測試(TWAA)以及氣味-酬賞聯結測試(ORA)。大鼠被分為五個組別,第一個組別的大鼠在亮期開始前先學習TWAA,第二組的老鼠在亮期開始時學習ORA,第三個組的老鼠在暗期開始時學習ORA,第四個組的老鼠先在亮期開始時學習TWAA,兩天後在亮期開始時學習ORA,第五個組的老鼠同樣連續學習TWAA與ORA,但在第一天TWAA學習後在特定的睡眠窗內給予快速動眼睡眠剝奪。研究結果發現,在ORA的學習前給予TWAA的訓練會增加ORA學習的成功率,但是ORA學習的指標,包含習得、記憶保持和再度學習的能力並未受到先前TWAA學習的影響而提升,雖然有此傾向。本研究採用一個新的方法來界定睡眠窗所在的時間點,即為每隔一個小時分析一次不同長度的睡眠窗在訓練前的睡眠以及訓練後的睡眠之變化。睡眠結構分析之結果顯示,在學習ORA之前先學習TWAA,和只學習ORA相較之下睡眠結構之變化有所不同,而此差異可能和兩者之行為表現傾向有差異相關。雖然由目前的結果看來,迴避記憶和氣味-酬賞聯結記憶可能為獨立運作的記憶系統,但因學習過兩者後睡眠結構和單純學習一種者並不相同,我們並不能排除兩個記憶系統因為其中部分的神經表徵重疊,導致連續學習後兩系統具有互動之情形的可能。
Sleep plays an important role in memory processing, while how sleep architecture change after independent or sequentially learning of two memory tasks (two-way active avoidance (TWAA) and odor-reward association (ORA)) involving common neural substrates are not yet investigated. In this study, rats were divided into five groups and respectively trained for the following tasks at different time points: the TWAA before light onset, the ORA during light onset, the ORA during dark onset, the TWAA before light onset and the ORA during light onset, the TWAA before light onset with deprivation of TWAA-induced 1st-day REM sleep window and the ORA during the light onset. Increase in rate of success in ORA learning was found after TWAA training, compared with pure ORA learning groups. However, latencies of acquisition, retention and relearning were not changed after TWAA training, although there is a tendency of facilitation. Sleep windows were identified in a new way that successive time blocks of different durations were determined between post-training sleep and pre-training baselines. Consolidation of avoidance memory before ORA training changed the sleep architectures of post-ORA-training sleep, compared to the pure ORA training group. Although current results suggest the independent operation of these memory systems, the change in sleep architecture after sequential learning of two tasks make it impossible to exclude the possibility that they may interact during sleep.
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