- Associated Press - Wednesday, December 14, 2016

LARAMIE, Wyo. (AP) - A neuroscience laboratory at the University of Wyoming is working to better understand the mechanisms that allow for communication and decision-making.

The research subjects in Jonathan Prather’s lab are about 4 inches long and weigh less than an ounce, and they definitely like to make noise, reported the Laramie Boomerang (https://bit.ly/2hr9pPv).

In fact, the songs and vocalizations of Bengalese finches are the subject of Prather’s research because the birds acquire their distinctive songs in a manner similar to human speech development.

Prather, a UW associate professor in the Department of Zoology and Physiology, talked about his research at a recent meeting of the Laramie Audubon Society, together with Ph.D. students Karagh Murphy and Jeff Dunning. Prather arrived at UW in 2010.

As Murphy explained, the learning of human speech happens first as infants listen to adult speech as a model. In time, they begin trying to imitate that speech, gradually acquiring and then mastering the ability to vocalize.

Songbirds follow a similar pattern. Male Bengalese finches are able to sing, while females are not. Young male finches, during their first month of life, listen to the songs of adult males around them. Then, they gradually start attempting their own songs, which Murphy compared to babies making babbling sounds.

“It doesn’t really sound like much of anything,” she said.

After a few months, though, the young males refine their songs so they sound like those of their adult mentors.

A dedicated circuit in the brain enables this learning to occur and is the subject of her research. One recent experiment involved observing neurons in an area of the brain that serves as a hub for channels for auditory input, learning and vocalizing.

“We have a method to eavesdrop on the neurons there,” she said.

Using an electrode the thickness of a human hair, Murphy recorded the firing of a neuron in this hub region. The electrode was attached while still allowing the bird to move freely and behave naturally, she said.

Using a microphone to record the bird’s song, she discovered the neuron fired in pattern with the singing.

“It fires every time he vocalizes a learned element of the song,” she said.

When she replayed the song for the bird, she found that the neuron also fired as the bird listened. Thus the cell’s firing corresponded both with motor output and auditory feedback.

“It’s a possible place of sensory motor correspondence,” she said.

While the male Bengalese finches are busy singing, the females are listening, choosing mates based on the quality of their song.

Their evaluations, also learned from their elders, differ from bird to bird. Understanding that process of deciding what makes a good song could give insight into human decision-making, Prather said.

Females don’t have the same brain features that Murphy has been studying in the males, but Dunning has been tracking the neural pathways they use in their evaluations.

One of his experiments involved optogenetics, which is the use of light-sensitive proteins found in algae to activate neurons in the finch brain. When the specialized protein is present in specific regions of the brain, a light can be used to activate those cells.

Dunning found that activating a region of the brain involved in song preference caused a female bird to double the number of calls she made in response to a song, even though the song was initially her least favorite among a group.

“We can activate circuits to increase calls,” he said.

Prather recently conducted an experiment designed to isolate the features of a song that are preferred by females. By placing a bird in a chamber with a camera, observers could watch a bird’s behavior in response to a song played through a microphone. The more calls the female made while listening, the more she favored the song.

Generally, Bengalese finch females prefer singing that shows both rapid frequency as well as large tonal sweeps - think of a person clapping both loudly and quickly, he said.

“That’s an honest signal of quality,” he said.

After isolating a female’s favorite song, researchers then tweaked that song by either changing the tempo or the frequency, but not both at once.

Prather said he expected that frequency would matter more, as the pitch of a song can indicate the size of the singer.

“Pitch had no impact on their preferences,” he said.

He did find that tempo mattered, but some birds liked a faster tempo while others liked a slower tempo.

“There’s no global right answer,” he said. “These birds disagree on what sexy is.”

Prather’s lab is a busy place, as it provides training for a host of undergraduate and graduate students.

Prather, Murphy and Dunning said their research, funded by agencies including National Science Foundation, NASA and National Institutes of Health, will continue as their research leads to new questions.

“These are studies that are still in progress,” Prather said.


Information from: Laramie Boomerang, https://www.laramieboomerang.com

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