Palchykova Svitlana, Winsky-Sommerer Raphaëlle, Tobler Irene
Institute of Pharmacology and Toxicology, University of Zurich, Switzerland.
Chronobiol Int. 2009 May;26(4):682-96. doi: 10.1080/07420520902926025.
There is increasing evidence that sleep facilitates memory acquisition and consolidation. Moreover, the sleep-wake history preceding memory acquisition and retention as well as circadian timing may be important. We showed previously that sleep deprivation (SD) following learning in OF1 mice impaired their performance on an object recognition task. The learning task was scheduled at the end of the 12 h dark period and the test 24 h later. To investigate the influence of the prominent circadian sleep-wake distribution typical for rodents, we now scheduled the learning task at the beginning of the dark period. Wakefulness following immediately after the learning task was attained either by gentle interference (SD; n = 20) or by spontaneous wheel running (RW; n = 20). Two control groups were used: one had no RW throughout the experiment (n = 23), while the other group's wheel was blocked immediately after acquisition (n = 16), thereby preventing its use until testing. Recognition memory, defined as the difference in exploration of a novel and of familiar objects, was assessed 24 h later during the test phase. Motor activity and RW use were continuously recorded. Remarkably, performance on the object recognition task was not influenced by the protocols; the waking period following acquisition did not impair memory, independent of the method inducing wakefulness (i.e., sleep deprivation or spontaneous running). Thus, all groups explored the novel object significantly longer than the familiar ones during the test phase. Interestingly, neither the amount of rest lost during the SD interventions nor the amount of rest preceding acquisition influenced performance. However, the total amount of rest obtained by the control and SD mice subjected to acquisition at "dark offset" correlated positively (r = 0.66) with memory at test, while no such relationship occurred in the corresponding groups tested at dark onset. Neither the amount of running nor intermediate rest correlated with performance at test in the RW group. We conclude that interfering with sleep during the dark period does not affect object recognition memory consolidation.
越来越多的证据表明，睡眠有助于记忆的获取和巩固。此外，记忆获取和保留之前的睡眠-觉醒历史以及昼夜节律时间可能也很重要。我们之前发现，在OF1小鼠学习后进行睡眠剥夺（SD）会损害它们在物体识别任务中的表现。学习任务安排在12小时黑暗期结束时，测试在24小时后进行。为了研究啮齿动物典型的显著昼夜睡眠-觉醒分布的影响，我们现在将学习任务安排在黑暗期开始时。学习任务后立即通过轻度干扰（SD；n = 20）或自发轮转跑步（RW；n = 20）来实现觉醒。使用了两个对照组：一组在整个实验过程中没有进行轮转跑步（n = 23），而另一组在获取后立即阻塞转轮（n = 16），从而在测试前阻止其使用。在测试阶段24小时后评估识别记忆，定义为对新物体和熟悉物体探索的差异。持续记录运动活动和轮转跑步的使用情况。值得注意的是，物体识别任务的表现不受这些方案的影响；获取后的清醒期不会损害记忆，与诱导觉醒的方法无关（即睡眠剥夺或自发跑步）。因此，在测试阶段，所有组对新物体的探索时间都显著长于对熟悉物体的探索时间。有趣的是，SD干预期间失去的休息量以及获取前的休息量都不会影响表现。然而，在黑暗期结束时进行获取的对照组和SD小鼠获得的总休息量与测试时的记忆呈正相关（r = 0.66），而在黑暗期开始时测试的相应组中没有这种关系。在RW组中，跑步量和中间休息都与测试时的表现无关。我们得出结论，在黑暗期干扰睡眠不会影响物体识别记忆的巩固。
