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Slixfeed · Sunday, 14 April - 13:00 edit
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Octopuses sleep—and possibly dream—just like humans
news.movim.eu / ArsTechnica · Thursday, 6 July, 2023 - 20:00 · 1 minute
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Re:Zero — Rem
Angelica · pubsub.movim.eu / anime · Monday, 24 October, 2022 - 18:57
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Jumping spiders may experience something like REM sleep
news.movim.eu / ArsTechnica · Monday, 8 August, 2022 - 22:42
Most creatures sleep, but until now, REM (rapid eye movement) sleep , the phase of sleep in which dreams occur, was thought to be exclusive to vertebrates. Octopuses appear to be the first invertebrates to show they are also capable of this
When it comes to neural function, studies have found these cephalopods are more like us than we think (pun somewhat intended). Having no spine hasn’t stopped them from evolving a complex nervous system. A 2022 study found that parts of their brains, the frontal and vertical lobes, work much like the hippocampus and limbic lobe in humans and other vertebrates. The hippocampus is critical to learning and memory, while the limbic lobe controls complex emotional reactions, such as the fight-or-flight response that is triggered by stress or fear.
Now it seems that octopuses have even more in common with us. In studying their sleep behavior, a team of researchers at the Okinawa Institute of Science and Technology observed both periods of quiet sleep, or NREM sleep (also known as slow wave sleep), and bursts of neural activity, during which the animals’ eyes and tentacles twitched while their skin changed color. Neural activities like these, which are similar to the waking state, only happen during REM sleep. Because they can transition between NREM and REM sleep, octopuses are the only known invertebrates that have two phases of sleep.
Our sleep is marked by cycles of distinct brain activity. The most well-known of these is probably rapid eye movement, or REM sleep, which is characterized by loss of muscle control leading to twitching and paralysis, along with its eponymous eye movements. REM sleep is widespread in vertebrates, appearing in many mammals and birds; similar periods have also been observed in lizards.
Figuring out what might be going on beyond vertebrates can get a bit challenging, however, as identifying what constitutes sleep isn't always clear, and many animals don't have eyes that move in the same way as those of vertebrates. (Flies, for example, must move their entire head to reorient their eyes.) But an international team of researchers identified a group of jumping spiders that can reorient internal portions of their eyes during what appears to be sleep.
And according to this team, the spiders experience all the hallmarks of REM sleep, with periods of rapid eye movements associated with muscle twitching.