News Release

Vocal neurons encode evolution of frog calls

Ancient circuits may have enabled evolution of vocal patterns in bats, primates

Peer-Reviewed Publication

Society for Neuroscience

Divergent Vocalizations

image: A vocal CPG underlies divergent vocalizations in X. laevis and X. petersii (A) Schematic representation of the known hindbrain vocal central pattern generator nuclei. The vocal motor nucleus (n.) IX-X contains vocal motor neurons. These neurons send their axons via the vocal (laryngeal) nerve to the larynx, the vocal effector organ. Fictive calling can be recorded from the vocal nerve using a suction electrode. Premotor neurons in the Xenopus parabrachial area (PBX) project monosynaptically to the vocal motor nucleus. In PBX, whole cell electrodes can record activity associated with fictive calling. (B) Representative example of X. laevis fictive calling, consisting of a series of long, fast rate CAP trills (~60 Hz; blue box, Nerve) and a simultaneously recorded premotor vocal neuron (Neuron). Temporally expanded recording (dashed box) of a single X. laevis call with introductory trill (grey box) and fast trill (blue box) and corresponding premotor neuron activity (right). view more 

Credit: Barkan et al., <i>JNeurosci</i> (2018)

A study of two closely-related frog species reveals a population of neurons that give rise to the unique mating calls of each species. Published in JNeurosci, the findings suggest that changes in the properties of these cells over the course of evolution may have shaped vocal patterns in vertebrates including bats and primates.

Clawed frog (Xenopus) species are distinguished by the vocalizations that males use to attract females. To investigate what contributes to these differences, Erik Zornik and colleagues compared the activity of premotor vocal neurons in dissected brains from two species, X. laevis and X. petersii, which diverged from a common ancestor about 8.5 million years ago.

Applying the neurotransmitter serotonin to the premotor parabrachial area of the isolated brains to produce fictive calls, the researchers identified two groups of cells in these closely-related species that are active during calls. They found that while the properties of Early Vocal Neurons were similar between the species, those of Fast Trill Neurons were unique and corresponded to the calls characteristic of each species. The parabrachial area is involved in the control of breathing across vertebrates, suggesting that these ancient circuits may have enabled the evolution of vocal patterns.


Article: Premotor neuron divergence reflects vocal evolution


Corresponding author: Erik Zornik (Reed College, Portland, OR, USA),

About JNeurosci

JNeurosci, the Society for Neuroscience's first journal, was launched in 1981 as a means to communicate the findings of the highest quality neuroscience research to the growing field. Today, the journal remains committed to publishing cutting-edge neuroscience that will have an immediate and lasting scientific impact, while responding to authors' changing publishing needs, representing breadth of the field and diversity in authorship.

About The Society for Neuroscience

The Society for Neuroscience is the world's largest organization of scientists and physicians devoted to understanding the brain and nervous system. The nonprofit organization, founded in 1969, now has nearly 37,000 members in more than 90 countries and over 130 chapters worldwide.

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