Samson David R, Vining Alexander, Nunn Charles L
Department of Anthropology, University of Toronto, Mississauga, Canada.
Department of Evolutionary Anthropology, Duke University, Durham, USA.
Anim Cogn. 2019 Sep;22(5):697-706. doi: 10.1007/s10071-019-01266-1. Epub 2019 May 4.
Primates spend almost half their lives asleep, yet little is known about how sleep influences their waking cognition. We hypothesized that diurnal and cathemeral lemurs differ in their need for consistent, non-segmented sleep for next-day cognitive function-including long-term memory consolidation, self-control, foraging efficiency, and sociality. Specifically, we expected that strictly diurnal Propithecus is more reliant on uninterrupted sleep for cognitive performance, as compared to four other lemur species that are more flexibly active (i.e., cathemeral). We experimentally inhibited sleep and tested next-day performance in 30 individuals of 5 lemur species over 960 total nights at the Duke Lemur Center in Durham, North Carolina. Each set of pair-housed lemurs experienced a sleep restriction and/or deprivation protocol and was subsequently tested in a variety of fitness-relevant cognitive tasks. Within-subject comparisons of performance on these tasks were made by switching the pair from the experimental sleep inhibited condition to a normal sleep environment, thus ensuring cognitive equivalency among individuals. We validated effectiveness of the protocol via actigraphy and infrared videography. Our results suggest that 'normal' non-disrupted sleep improved memory consolidation for all lemurs. Additionally, on nights of normal sleep, diurnal lemurs performed better in foraging efficiency tasks than cathemeral lemurs. Social behaviors changed in species-specific ways after exposure to experimental conditions, and self-control was not significantly linked with sleep condition. Based on these findings, the links between sleep, learning, and memory consolidation appear to be evolutionarily conserved in primates.
灵长类动物一生中近一半的时间都在睡眠，但关于睡眠如何影响它们清醒时的认知，我们却知之甚少。我们假设，昼行性和晨昏性狐猴在对次日认知功能所需的持续、无分段睡眠方面存在差异，这些认知功能包括长期记忆巩固、自我控制、觅食效率和社交能力。具体而言，我们预计，与其他四种活动时间更灵活（即晨昏性）的狐猴物种相比，严格昼行性的冕狐猴在认知表现上更依赖不间断的睡眠。我们在北卡罗来纳州达勒姆的杜克狐猴中心，对5种狐猴的30只个体进行了960个夜晚的实验，通过抑制睡眠来测试次日的表现。每对圈养的狐猴都经历了睡眠限制和/或剥夺方案，随后在各种与适应性相关的认知任务中接受测试。通过将配对从实验性睡眠抑制条件切换到正常睡眠环境，对这些任务的表现进行个体内比较，从而确保个体之间的认知等效性。我们通过活动记录仪和红外摄像验证了该方案的有效性。我们的结果表明，“正常”的无干扰睡眠改善了所有狐猴的记忆巩固。此外，在正常睡眠的夜晚，昼行性狐猴在觅食效率任务中的表现优于晨昏性狐猴。暴露于实验条件后，社交行为以物种特异性的方式发生了变化，并且自我控制与睡眠条件没有显著关联。基于这些发现，睡眠、学习和记忆巩固之间的联系在灵长类动物中似乎在进化上是保守的。
