Putting mice into hibernation causes a major loss of synapses
摘要
将小鼠诱导进入类冬眠状态后，其大脑中超过一半的突触连接被“抹除”，但小鼠的记忆似乎并未丢失。该研究通过激活下丘脑中的Q神经元实现这一状态，旨在探究记忆如何在不断变化的神经连接中长期保存。结果显示，尽管突触状态发生剧烈改变，记忆仍得以维持，为记忆存储机制提供了新线索。
Our leading hypothesis for how our memories are stored is that when you learn something, the connections among neurons involved get stronger and physically larger, and that constitutes the memory. The trouble is that these connections significantly change over time—they’re plastic.
“If you compare the arrangement of these connections on day one with the same on day four or five, it's very, very different," says Kazumasa Tanaka, a neuroscientist at the Okinawa Institute of Science and Technology Graduate University in Japan. To learn how a memory that can last for years can sit on hardware that shifts every few days, Tanaka’s team made the shift a bit more dramatic. In a recent Science study, they induced a hibernation-like state in mice, which basically erased the state of more than half of their synapses. And yet the mice apparently have kept their memories.
Hibernation on demand
Hibernation is a specialty of squirrels, hamsters, and bears, but the neural circuit that triggers it is conserved across mammals, and is present in species that never hibernate in the wild—like mice. In June 2020, a team of researchers led by Takeshi Sakurai, a neuroscientist at the University of Tsukuba and a collaborator on Tanaka’s study, developed a technique to artificially activate this hibernation circuit. This can be done by activating a population called Q neurons in a region of the hypothalamus.
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