For the first time, scientists have recorded brain waves from freely moving octopuses. The data reveal some unexpected patterns, though it’s too early to know how octopus brains control the animals’ behavior, researchers report February 23 in Current Biology.
“Historically, it’s been so hard to do any recordings from octopuses, even if they’re sedated,” says neuroscientist Robyn Crook of San Francisco State University, who was not involved in the study. “Even when their arms are not moving, their whole body is very pliable,” making attaching recording equipment tricky.
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Octopuses also tend to be feisty and clever. That means they don’t usually put up with the uncomfortable equipment typically used to record brain waves in animals, says neuroethologist Tamar Gutnick of the University of Naples Federico II in Italy.
To work around these obstacles, Gutnick and colleagues adapted portable data loggers typically used on birds, and surgically inserted the devices into three octopuses. The researchers also placed recording electrodes inside areas of the octopus brain that deal with learning and memory. The team then recorded the octopuses for 12 hours while the cephalopods went about their daily lives — sleeping, swimming and self-grooming — in tanks.
Some brain wave patterns emerged across all three octopuses in the 12-hour period. For instance, some waves resembled activity in the human hippocampus, which plays a crucial role in memory consolidation. Other brain waves were similar to those controlling sleep-wake cycles in other animals.
The researchers also recorded some brain waves that they say have never been seen before in any animal. The waves were unusually slow, cycling just two per second, or 2 hertz. They were also unusually strong, suggesting a high level of synchronization between neurons. Sometimes just one electrode picked up the weird waves; other times, they showed up on electrodes placed far apart,
Observing these patterns is exciting, but it’s too early to tell whether they’re tied to a specific behavior or type of cognition, Gutnick says. Experiments with repetitive tasks are necessary to fully understand how these brain areas are activated in octopuses during learning.
The new research is exciting in that it provides a technique for future researchers to observe brain activity in awake and naturally behaving octopuses, Crook says. It could be used to explore brain activity behind the animals’ color-changing abilities, spectacular vision, sleep patterns and adept arm control (SN: 1/29/16; SN: 3/25/21).
Octopuses are highly intelligent, so by studying the creatures “you can get ideas about what is important for intelligence,” Gutnick says. “The problems that the animals face are the same problems, but the solutions that they find are sometimes similar and sometimes different and all of these comparisons teach us something.”