Dolphins and Bats: Similar Neural Pathways

Dolphins are not only super-smarties, but they use at least two pathways in their brains to process sound. This makes their neural pathways look surprisingly like a bat's. 

That's according to researchers at Emory University, who note that while dolphins and bats both use echolocation to sense their environments, most scientists wouldn't expect to find strong similarities between the two animals' brains. They recently reported their findings in the journal the Proceedings of the Royal Society B. 

"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," says Gregory Berns, a neuroscientist at Emory University and lead author of the study, in a release.

The scientists learned this when they used diffusion tensor imaging (DTI) on the preserved brains of two dolphins that stranded on a California beach more than 10 years ago. Using DTI on a non-living brain had only been tried previously on deceased humans, primates, and rats. The method was developed by study coauthors from the University of Oxford, says a release. 

Scanning the post-mortem, football-sized dolphin brains took longer--about 12 hours--than scanning a brain with more liquid in it. The preserved brains retained only small amounts of the water found in healthy tissue, the release said. 

With the data from the DTI scans, researchers mapped the white matter pathways, finding the wiring diagram for the dolphin brain, in high detail. The fact that dolphins use sound for different purposes--to communicate, navigate, and hunt--may be why the mammals have more than one neural area associated with sound, researchers noted in the release. 

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