Brain-reading electrodes in a free-ranging octopus.

Ars Technica reports on an underwater electronic neurological breakthrough. A group of researchers from Naples, Okinawa, and further afield who have used implanted recording electrodes to monitor three captive but free-moving octopuses, and found some very interesting things about the way they think:

Using recording electrodes, the researchers found a type of brain wave never before seen, along with brain waves that may be similar to some seen in human brains, possibly providing hints about the evolution of intelligence.

“The enormous difference between octopuses and us stems from over 550 million years of independent evolution,” explained Dr. Michael Kuba, the OIST project leader for the 2023 octopus brainwave study who now works at Naples University. “Our closest common ancestor probably resembled a flatworm.” Yet Kuba and his team are looking at the few similarities to learn more about the evolution of mental abilities.

“Since the octopuses have eight ultra-flexible arms that can reach any part of their body and have a soft body with no skull to anchor the recording equipment, the challenge of this project was to realize a new equipment that was out of reach,” said Dr. Anna Di Cosmo, a professor at the University of Naples and a researcher involved in the 2023 study.

Reach matters because the animal often removes or plays with the recording equipment. Kuba, Di Cosmo, and others decided to take a new approach by implanting their recording devices inside the octopus’s brain, far out of reach.

When the team looked at an octopus’s brain waves for the first time, the results were shocking. As Di Cosmo explained, these signatures were “long-lasting, slow oscillations that have not been described before.” As far as we know, these signatures appear to be unique to the octopuses.

Perhaps even more surprising was that several brain wave signatures mimicked those in humans and other mammals. “We now had an opportunity to observe memory formation in the octopus and compare it to mammals, to identify common motifs or distinct idiosyncrasies in brains that have developed completely independently,” explained Dr. Tamar Gutnick, the paper’s first author and a visiting scientist at the University of Naples. This project “gave us the chance to study brains with complex behaviors and cognition that are evolutionarily separated from vertebrates by at least 500 million years,” Kuba added. “This gives us a chance to see general principles on how brains need to work [to be considered intelligent].”

You can read more about the octopus findings here, in Current Biology.