冬眠（Hibernation）是一些物种为了适应极端生存环境，趋同演化出的一种周期性的生理现象。
冬眠使熊和啮齿动物等哺乳动物能够在恶劣的天气条件或缺乏食物的情况下生存。在这种深度睡眠状态下，它们的新陈代谢处于最低水平，生理机能发生变化。它们的体温下降，心脏跳动频率降低，肌肉和骨骼进入休息状态，但仍然保持力量。
Hibernation enables mammals such as bears and rodents to survive adverse weather conditions or a lack of food. During this deep sleep state, their metabolism is at a minimum level and their physiology changes. Their body temperature drops, some organs shut down, the heart barely beats, while muscles and bones enter a resting state but maintain strength.
图源：视觉中国人工冬眠的想法长期以来一直吸引着科幻迷的想象力：从《星际迷航》到《2001：太空漫游》。在现实中，对冬眠的研究不是仅为了太空旅行者，这项技术还能使那些正在等待器官移植或面临侵袭性癌症的人受益。The idea of inducing hibernation in humans has long captured the imagination of science fiction fans – from the Grizzelas in the Star Trek movies to the passengers travelling to Jupiter in 2001: A Space Odyssey. In reality, research into hibernation is not just for space travellers – it could also benefit people who are waiting for organ transplants or facing aggressive cancers.有人希望在冬眠中飞往外太空，有人希望在冬眠中得到生命的延续。但是在现实世界，我们距离人工冬眠究竟还有多远呢？科幻小说迷狂喜：人工冬眠有发现来自中国科学院深圳先进技术研究院副研究员戴辑和他的团队已经发现，人体的寒冷防御机制可能是阻止人工冬眠的障碍。Researchers, neuroscientist Dai Ji and his team from the Shenzhen Institute of Advanced Technology, say they have identified a potential obstacle that could prevent humans from being put into a state of hibernation.
这项研究实现了世界首次对非人灵长类动物进行细胞级低温实验，研究小组激活了猕猴大脑中的特定神经元，而这些神经元恰好可以引发体温的轻微下降和对寒冷的强烈防御性反应。In the world’s first cell-level hypothermia experiment on primates, the team activated specific neurons in the brains of the monkeys that triggered just a slight drop in body temperature and a strong defensive response against the cold.在以前的研究中，在类似实验中转基因鼠类体温会下降约10℃，但研究人员发现，猴子体温只降了1℃左右。与此同时，这些猴子不停地走动，它们的心脏跳动得更快，而且还在发抖——这些都是为了对抗下降的体温。Similar experiments on mice and rats in previous studies have resulted in a decrease in body temperature of about 10 degrees Celsius. But the monkeys cooled down by just 1 degree or so. Meanwhile, the monkeys kept moving around, their hearts were beating much faster and they were shivering – all in an effort to combat the falling body temperature.
图源：视觉中国“我们的研究表明，如果人类要实现人工冬眠，一个主要的挑战将是抑制我们的寒冷防御机制。”戴辑表示。"Our study showed that if humans are to realise artificial hibernation, a primary challenge would be to suppress our cold defence mechanism," Dai said in an interview.“关于为什么许多哺乳动物会冬眠而人类不会冬眠已经有很多猜测。由于以前的研究都集中在啮齿类动物上，我们想尝试在身体大小和结构上与人类更相似的动物模型。”戴辑说。"There has been much speculation about why many mammals hibernate but humans dont," Dai said. "Since previous studies have focused on rodents, we wanted to try an animal model thats more similar to human beings in body size and structure."
图源：The Innovation研究人员在他们的研究中使用了三只猕猴。其中两只作为实验对象，一只作为对照。利用化学遗传学工具，展开神经调控体温研究。该团队发现，升高下丘脑视前区（preoptic area）一类进化保守的兴奋性神经元的活性，可以促进动物降低体温。The researchers used three macaques in their study – two as experimental subjects and one as control. With a technique known as chemogenetic activation, they turned on neurons in the so-called preoptic area — a nucleus deep down in the ventral part of the monkey brain.实验中发现，两只实验组猕猴的体温下降了大约0.4-0.5℃，它们也开始比对照组更剧烈地走动。研究人员在限制实验组的活动之后，它们的体温进一步下降0.7-0.9℃。As a result, the body temperature of the two monkeys dropped by about 0.4-0.5 degrees, but they also began to move around much more vigorously than the controlled one. The researchers restricted the monkeys’ movements, which led to a further decrease of 0.7-0.9 degrees in their body temperature.
激活猕猴下丘脑视前区神经元降低了体核温度。图源：中科院深圳先进院与小鼠存在显著差异的是，非人灵长类动物对体温的变化非常敏感。当体温降低约0.5℃的时候，动物已经通过加速心率、肌肉颤栗、收缩外周血管等自主神经机制产热，抵抗体温的降低。同时动物大幅增加运动量，通过运动产热，抵御体温的降低。由此可见，非人灵长类动物有着更强的御寒能力。后来，研究小组用核磁共振扫描发现整个猴子的大脑普遍激活。戴辑说：“一种可能的解释是，猴子有一种先天的寒冷防御机制，这种机制在啮齿类动物中是缺失的，能够以不到1℃的高精确度感知温度变化。”Later, the team found a general activation in the entire monkey brain using MRI scans. “One possible explanation is that monkeys have an innate cold defence mechanism which is missing in rodents, to perceive temperature changes with high accuracy of less than 1 degree Celsius,” he said.持续探索冬眠奥秘戴辑和他的团队现在研究体温降低如何影响灵长类动物的认知能力。他说：“我们的下一个实验将测试猴子的工作记忆和其他认知指标。这很重要，因为虽然宇航员在飞入深空时身体处于冬眠状态，但他们的大脑仍然需要工作。”Dai and his team now plan to look at how lowered body temperature might affect the cognitive abilities of primates. "Our next experiments will test working memory and other cognitive indicators in monkeys. This is important because while astronauts physically hibernate as they fly into deep space, their brain still needs to be working."
图源：视觉中国戴辑说，如果科学家能够找到“冬眠基因”，将会帮助人体科学研究进一步深入。一种理论认为，冬眠在人类基因中被编码，但这种拯救生命的技能因为不再需要而丢失。因此，能找到“冬眠基因”，科学家想出如何触发这一机制，那么这种能力就有可能被恢复。Dai said it would help if scientists could find the "hibernation gene". One theory is that hibernation is encoded in human genes, but that the life-saving skill was lost because it was no longer needed. So if it could be found, and if scientists could work out how to trigger it, then this ability could potentially be restored.编辑：朱迪齐实习生：侯琼来源：南华早报 中国科学院深圳先进技术研究院
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