睡眠是否能鞏固陳述性記憶目前尚無定論。過去研究一致較支持睡眠能增進相關字詞配對的學習，但睡眠是否能增進無關字詞配對的學習，目前仍存在不一致的發現。造成該差異的原因可能是：過去研究多採用的行為測量指標，或許無法充分反映出睡眠促進記憶新聯結（new association）產生的效果。事件關聯電位（Event-related potential, ERP）的N400反映出語意記憶系統內每個字詞彼此的相關程度，因此本研究使用N400來探討睡眠強化無關字詞配對形成新聯結的電生理歷程。30名健康受試者（15位男性與15位女性，平均年齡為20.7歲） 隨機分派至睡眠組或清醒組，第一晚在學習80組無關字詞配對後，接受第一次再認記憶測驗，同時進行ERP的記錄。隨後睡眠組接受睡眠記錄（PSG），清醒組則接受整晚的睡眠剝奪，兩組受試者皆在第二晚給予8小時的躺床時間，使他們有機會充足睡眠以恢復精神，於第三天早上接受第二次再認記憶測驗及ERP記錄。在記憶測驗時，無關字詞配對分別組成促發字（prime）與目標字（target）先後出現，受試者需判斷先後出現的字詞是否為先前學過的完整配對，在測試階段同時記錄腦電波訊號。行為測量結果顯示睡眠過後，再認表現的正確率顯著提高且反應時間明顯縮短，但在睡眠剝奪後則顯示相反的結果。電生理測量發現睡眠組的N400振幅在睡眠過後較清醒組明顯降低。另外，睡眠組較清醒組有較高的正確率與較短的反應時間。睡眠組再認測驗的進步量與慢波睡眠呈現負相關，而慢波睡眠與第一次再認測驗的正確率呈現正相關，根據二階段睡眠記憶鞏固理論，慢波睡眠涉及重新組織記憶的歷程（系統性固化），因此學習表現較佳的受試者出現較多的深度睡眠，可能反應其經歷系統性固化。本研究結果顯示睡眠對於產生新聯結有明顯的增強效果，而且慢波睡眠可能參與了記憶表徵重新分配的歷程。 / The effect of sleep on declarative memory remains contradictory. Prior studies show that sleep benefits the learning of related word pairs consistently, while the learning of unrelated word pairs, however, show mixed results. It is possible that the behavioral measures used in previous studies are not sensitive enough to reveal subtle effects of sleep on new associations. N400, an event-related potential (ERP) component reflecting relatedness among words in semantic memory, was used in the present study to investigate the effect of sleep on the physiological process underlying new associations of unrelated word pairs. Participants were randomly assigned to either a Sleep group or a Wakefulness group. In the learning phase, participants were asked to memorize 80 visually presented unrelated word-pairs, followed by a pre-test phase with a recognition task. The participants then underwent either a night of nocturnal sleep (Sleep group) or sleep deprivation (Wakefulness group). A post-test was conducted after subjects had one night of recovery sleep. During both pre-test and post-test sessions, prime and target words were presented successively for the subjects to judge whether they were among the original pairs or new pairs. ERPs were recorded during both test phases. The behavioral data show that differences in improvement of recognition and decreases in reaction time from pre-test to post-test are significant between Sleep and Wakefulness groups. N400 peak amplitude attenuated significantly after sleep but not after wakefulness. The improvement of recognition negatively correlates with slow wave sleep (SWS). The number of word-pairs acquired in the learning phase, however, correlates positively with SWS. According to the two-stage memory consolidation theory of sleep, SWS involves in redistribution of memory (systematic consolidation). Therefore, that the participants with high performance showed more SWS may reflect the process of systematic consolidation. These results suggest that the sleep has an enhancing effect on the formation of novel association, and SWS may be involved in the process of redistributing memory representations.
| Identifer | oai:union.ndltd.org:CHENGCHI/G0957520021 |
| Creators | 林俊成, Lin, Chun Cheng |
| Publisher | 國立政治大學 |
| Source Sets | National Chengchi University Libraries |
| Language | 英文 |
| Detected Language | English |
| Type | text |
| Rights | Copyright © nccu library on behalf of the copyright holders |
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