Fish tale tells communication story

CORNELL (US) — The grunts and hoots that make up fish chatter offer a basic wiring diagram for how all vertebrates, including humans, communicate.

Just like walking or swimming, the brains of animals with a backbone need to use timing signals to carefully coordinate the right muscles in order to make sound.

In a study of midshipman fish published online in the journal Nature Communications, researchers identified two distinct groups of neurons, part of a central pattern generator, in the hindbrain that independently control the duration and the frequency of sounds used for calling.

Specifically, the pattern generator directly coordinates and synchronizes the actions of muscles of the midshipman’s swim bladder, where the sounds are produced; an action that is analogous to how the human larynx or avian syrinx works.

“If you can understand the simplest system, it provides a road map for understanding the fundamental working units in the central nervous system for how you build a vocal system,” says Andrew Bass, professor of neurobiology and behavior at Cornell University and senior author of the paper.

“It’s been relatively unknown how brains coordinate vocalization,” he says. “People think it’s different from walking,” in terms of patterning in the brain, “but it really works according to a similar set of rules.”

Researchers used standard methods to locate the hindbrain areas that contribute to vocalizations; tiny electrodes recorded the activity of nerve cells and revealed the brain’s electrical code. Computer software then allowed them to decipher the data and figure out the functions of the neurons.

In earlier research, Bass identified this same region of the brain in larval midshipman fish, showing how it is present in the brains of other animals, including primates, suggesting the vocal networks in all vertebrates evolved from an ancestrally shared brain area that originated in fishes.

“Studies like these allow us to trace the evolutionary history of the brain,” Bass says. “All animals, including humans, share many brain circuits for complex behaviors, including the use of sounds for social communication.”

Researchers at New York University contributed to the study that was funded by the Grass Foundation and the National Institutes of Health.

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