Scientists have recorded brainwaves of free-roaming octopuses for the first time. The data show some unexpected patterns, although it’s still too early to know how octopus brains control animal behavior, researchers report Feb. 23 in Current Biology.
“In the past, it was so difficult to record squid even when they were sedated,” says Robyn Crook, a neuroscientist at San Francisco State University who was not involved in the study. “Even when her arms aren’t moving, her whole body is very flexible,” which makes attaching recording devices difficult.
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Octopuses also tend to be feisty and smart. That means they don’t typically put up with the uncomfortable equipment typically used to record brainwaves in animals, says neuroethologist Tamar Gutnick of the University of Naples Federico II in Italy.
To circumvent these obstacles, Gutnick and colleagues adapted wearable data loggers typically used in birds and surgically inserted the devices into three octopuses. The researchers also placed recording electrodes in areas of the squid’s brain that deal with learning and memory. The team then recorded the squid for 12 hours while the cephalopods went about their daily lives – sleeping, swimming and self-care – in tanks.
Some brainwave patterns emerged in all three squids over the 12-hour period. For example, some waves resembled activity in the human hippocampus, which plays a crucial role in memory consolidation. Other brainwaves were similar to those that control sleep-wake cycles in other animals.
The researchers also recorded some brain waves that they say have never been seen in an animal before. The waves were unusually slow, alternating only two per second, or 2 hertz. They were also unusually strong, suggesting high levels of synchronization between neurons. Sometimes only one electrode picked up the strange waves; another time they showed up on widely spaced electrodes,
Observing these patterns is exciting, but it’s too early to tell if they’re linked to a specific behavior or type of cognition, Gutnick says. Experiments with repetitive tasks are needed to fully understand how these brain areas are activated during learning in octopuses.
The new research is exciting in that it offers future researchers a technique to monitor brain activity in awake and naturally behaving squid, Crook says. It could be used to study the brain activity behind the animals’ color-changing abilities, spectacular vision, sleeping patterns and dexterous arm control (SN: 01/29/16; SN: 03/25/21).
Octopuses are highly intelligent, so “by studying the creatures you can get a picture of what’s important for intelligence,” says Gutnick. “The problems that animals face are the same problems, but the solutions they find are sometimes similar and sometimes different, and all of these comparisons teach us something.”