Neuroscientists Map Echolocation Systems in the Dolphin Brain
Neuroscientists have for the first time mapped the sensory and motor systems in the brains of dolphins, and shown that at least two areas of the dolphin brain are associated with the auditory system, unlike most mammals that primarily process sound in a single area.
The research is published in Proceedings of the Royal Society B with the title “Diffusion tensor imaging of dolphin brains reveals direct auditory pathway to temporal lobe.” The paper is freely available online.
Dolphins Are the Most Sophisticated Users of Biological Sonar
“Dolphins are incredibly intelligent, social animals and yet very little is known about how their brains function, so they have remained relatively mysterious,” says lead author Gregory Berns, a neuroscientist at Emory University. “We now have the first picture of the entire dolphin brain and all of the white matter connections inside of it.”
The researchers applied a recently developed technique called diffusion tensor imaging (DTI) on the preserved brains of two dolphins who died after stranding on a beach in North Carolina more than a decade ago. DTI focuses on the brain’s white matter, or the fiber pathways that connect neurons and different regions of the brain’s gray matter, and can detect the movement of water molecules along these fiber tracks. The data from the DTI scans allowed the researchers to map the wiring diagram for the dolphin brain, in high detail.
Based on the results, the scientists think that dolphins have more than one neural area associated with sound because they are using sound for different purposes. In fact dolphins, like bats, can perceive objects by echolocation – bouncing sound off surfaces. “Dolphins are the most sophisticated users of biological sonar in the animal kingdom,” says co-author Lori Marino, a neuroscientist specializing in the brains of dolphins, whales and other cetaceans.
“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,” adds Berns. “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.
Echolocation for People?
Echolocation sounds like a great thing to have. Is there a way for people to perceive objects by echolocation? In related news, scientists at University of California, Berkeley, have used graphene to build lightweight ultrasonic loudspeakers and microphones, enabling people to mimic the echolocation ability of bats and dolphins.
“Sea mammals and bats use high-frequency sound for echolocation and communication, but humans just haven’t fully exploited that before, in my opinion, because the technology has not been there,” said UC Berkeley physicist Alex Zettl. “Until now, we have not had good wideband ultrasound transmitters or receivers. These new devices are a technology opportunity.”
Images from Wikimedia Commons.