They are highly intelligent, although they are not even remotely related to us. How does the strange yet powerful octopus brain work? Clever technology can now provide insights: Researchers have implanted electrodes in the brains of octopuses and housed a recording device for neuronal activity in their bodies. In connection with video recordings of the freely moving animals, they were able to gain initial indications of special brain activity patterns. Above all, there is now potential for further research, say the scientists.
Eight squirming arms with suction cups, three hearts, blue blood… Many features of the octopus are downright alien-like. The reason for this is that the lineage of cephalopods separated from that of our ancestors early in evolutionary history. The octopuses are assigned to the molluscs – they are therefore related to mussels or snails. Surprisingly, however, they still have one characteristic that connects them to the highly developed representatives of mammals: octopuses are amazingly clever – they can learn, solve tricky tasks and even use tools. One thing is clear: their intelligence is based on a complex brain, which has apparently also been able to produce great performance over the course of evolutionary history.
However, it is not yet clear how the specially constructed nerve structure works – for example, how it controls or “thinks” the eight arms. In humans and vertebrates, brain functions can be examined by measuring brain waves and linked to behavior. So far, however, this has hardly seemed possible with the octopuses. Hardly anything can be attached to the slippery and wobbly molluscs. In addition, they would immediately tear off any foreign objects on their body surface. “With their eight strong and extremely flexible arms, they can reach any part of their body,” says lead author Tamar Gutnick of the Okinawa Institute of Science and Technology. “So we needed a way to get the devices completely out of reach. That’s why we built them into the animals,” says the researcher.
Implanted instead of attached
The team adapted small and lightweight data loggers originally developed for monitoring brain activity in birds during flight. The team waterproofed these devices without greatly enlarging them and equipped them with special batteries that allowed continuous recording for up to 12 hours. The researchers chose the relatively large octopus species Octopus cyanea as a model animal in order to be able to accommodate the system well. They stunned three specimens and inserted the recording device into a cavity in the muscular wall of their mantle. It was connected to fine electrodes implanted in an area of the octopus’ brain called the vertical lobe and median superior frontal lobe.
After the surgery was completed and the opening sealed, the octopuses were returned to their home tank and awoke from the anesthesia. They were then monitored by video cameras for twelve hours. The device then recorded the patterns of brain activity in parallel with their behaviors such as sleeping, eating and moving. The loggers and electrodes were then surgically removed from the test animals and the researchers were able to read out the data and synchronize it with the video recordings.
Promising proof of concept
As the team reports, they noticed several different patterns of brain activity, some of which resembled those found in mammals. However, they also found special, very long-lasting and slow oscillation patterns that had not previously been described. Concrete conclusions about connections with certain behaviors are not yet possible, say the researchers. However, as they emphasize, their study is primarily a proof of concept intended to illustrate the potential of the process.
They now plan to use the system while the animals solve special tasks. “The focus should be on the area associated with learning and memory. We hope to be able to do that very soon,” says Gutnick. According to the researchers, the method could be used with different representatives of cephalopods and thus help to gain insights into the basis of their special cognitive abilities. Like how they interact or control the movement of their bodies and their many arms. “This is an important study – but only the first step,” says senior author Michael Kuba of the University of Naples Federico II. “Squids are so clever, but we know so little about how their brains work. With this technique, we now have the ability to look inside these organs as they perform specific tasks. It’s really exciting and thrilling,” says the scientist.
Source: Okinawa Institute of Science and Technology (OIST) Graduate University, professional article: Current Biology, doi: 10.2139/ssrn.4309084