Neuroscientists compared brains from coyotes and three pinniped species to find why some mammals are vocally flexible. The work, published in Science, was led by Emory University and New College of Florida. The study used diffusion magnetic resonance imaging on postmortem brains to trace neural pathways.
The sample included four California sea lions, four harbor seals, three northern elephant seals and four coyotes. All brains came from wild animals that died naturally at rehabilitation centers or were euthanized for injuries, and some coyotes were euthanized at a United States Department of Agriculture facility in Utah. The diffusion MRI method for non-living brains was developed by Karla Miller at the University of Oxford. Gregory Berns and Peter Cook applied the method to map 15 brain regions involved in vocal control.
Results showed a major wiring difference. In coyotes the mid-brain links to brainstem cells that drive vocal muscles. In the pinnipeds the vocal motor cortex has a direct pathway to the brainstem, bypassing the mid-brain. Elephant and harbor seals also showed strong auditory–vocal connections, and harbor seals had especially strong links between the thalamus and vocal motor cortex. The team suggests this bypass evolved as pinnipeds developed precise breath and swallowing control for life underwater, and they plan studies in whales, dolphins and porpoises.
Difficult words
- postmortem — after an animal or person has died
- neural pathway — nerve connection between brain areasneural pathways
- brainstem — lower part of brain controlling basic functions
- vocal motor cortex — brain area that controls voice muscles
- euthanize — humanely end the life of an animaleuthanized
- bypass — a path that avoids a normal routebypassing
- thalamus — brain region that relays sensory information
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Discussion questions
- How might direct pathways from cortex to brainstem help pinnipeds produce sounds underwater?
- Do you think studying postmortem brains gives reliable information about living animals? Why or why not?
- Which result in the article surprised you most, and why?
