Scientists have for the first time mapped the brains of dolphins.
Neuroscientists, writing in the Proceedings of the Royal Society B, found that at least two areas of the dolphin brain are associated with the auditory system. Most mammals process sound in a single area.
“Dolphins are incredibly intelligent, social animals and yet very little is known about how their brains function, so they have remained relatively mysterious,” says Gregory Berns, a neuroscientist at Emory University and lead author of the study.
“We now have the first picture of the entire dolphin brain and all of the white matter connections inside of it.”
The researchers worked on the preserved brains of two dolphins who died after stranding on a beach in North Carolina more than a decade ago.
The study focused on the dolphin auditory system, since dolphins use echolocation to sense their environments.
“We found that there are probably multiple areas in the dolphin brain associated with auditory information, and the neural pathways look similar to those of a bat,” Berns says.
“This is surprising because dolphins and bats are far apart on the evolutionary tree. They diverged tens of millions of years ago but their brains may have evolved similar mechanisms for using sound not just to hear, but to also create mental images.”
Previous investigations using magnetic resonance imaging (MRI) have revealed the complex anatomy of cetacean brains. But these capture only the brain’s basic structure.
The latest study used diffusion tensor imaging (DTI) which focuses on the brain’s white matter, or the fibre pathways which connect neurons and different regions. DTI can detect the movement of water molecules along these tracks.
Dolphins emit clicks, squawks, whistles and burst-pulse sounds to communicate, navigate and hunt. Echolocation allows them to perceive objects by bouncing sound off surfaces.
The researchers hope that their map of dolphin neural circuitry will help unlock secrets of the dolphin mind, including how they communicate and perceive their environment.