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Birds' brains reveal source of songs

Scientists have yearned to understand how the chirps and warbles of a young bird morph into the recognizable and very distinct melodies of its parents. Neuroscientists at the McGovern Institute for Brain Research at MIT now have come one step closer to understanding that process. They've shown for the first time how a particular brain region in birds serves as the source of vocal creativity.

"It's an extraordinary finding," says Sarah Bottjer of the University of Southern California. "Here's an organism that enables a direct investigation of how animals learn motor activities."

The songbird's creative, trial-and-error type of learning provides an ideal model for studying similar processes in humans, such as how a baby's babble takes on the conversational cadences and recognizable syllables of mama and papa. Likewise, the brain pathways involved in birdsong have a human counterpart, the poorly understood basal ganglia circuit, so birds may have something to teach us about our own brains and what we learn may eventually apply to human diseases that affect motor abilities, such as Parkinson's disease.

"The question we're trying to answer is how a young bird learns its song," says Professor Michale Fee of MIT's McGovern Institute about his recent study, which was published online in advance of the May issue of the free access journal, Public Library of Science Biology. "We've known there are several brain areas involved: a motor circuit for producing the song, and a learning circuit, called the AFP (for anterior forebrain pathway), that sends its output to the motor system."

Normally, the young zebra finch nursery resounds with ever-new, imperfect variations of the adult songs. Gradually, the youngsters' songs become less variable and more true to the old standards. Some years ago, Bottjer had observed that disabling a young finch's AFP circuit stopped the learning in midstream. The bird still sings, but never learns the right song. To explain this effect, scientists theorized that the AFP circuit helps the juvenile compare its immature efforts with its parent's (usually the father's) example. That hypothesis, however, did not explain how all the playful variability in the little bird's babble arose in the first place.

For years, nobody had followed up on that question.

"We framed the question in a different way," Fee says of his research with postdoctoral fellow Bence P. Ölveczky and graduate student Aaron Andalman. "We said, this young bird is being creative, exploring many different sounds through trial and error. We hypothesized that the AFP is the source of this creativity, generating the variations, rather than comparing them."

To test this theory, Fee's team studied finches that were just old enough to begin their vocal explorations. The researchers temporarily inactivated the part of the AFP connecting to the motor system used in producing songs. That inactivation shut down all the variability, temporarily stranding the young finch with an immature version of the song.

These results suggested that the AFP circuitry itself causes the juvenile bird's experimentation with various sounds and sequences, and that such explorations are essential to learning songs. Deactivating the AFP after a bird had already learned the correct song had no effect on its continued proficiency.

The researchers then learned that the AFP neurons produce random bursts of activity coinciding with new variations in the practice routine.

"We think the bursts of these neurons 'kick' the motor pathway that is producing a song, jarring it out of the routine and making it sing something new," Fee says. Then another, still unexplained, pathway compares that variation to the bird's memory of the father's song. Gradually, the bird gets it right more often and eventually sings only the songs of its elders.

Source: MIT
Источник: http://www.physorg.com/news3905.html

Коротко о сути:

Множество птиц умеют петь, при этом каждый вид различается своей "песней". Часто и запах и внешний вид разных птиц очень похожи, но птицы одного вида легко находят друг друга.
Проведенное исследование показало, что, не смотря на генетически заложеные основы пения, песням птицы учатся у родителей. Если птенца забрать у родителей - он скорее всего будет петь "неправильную" песню.
Связывают это со свойством молодежи к экспериментам. В процесе роста молодняк путем проб и ошибок пытается повторить песни своих родителей. С возрастом молодые птицы все чаще и чаще попадают "в унисон" и, в конце концов, поют только песню своих родителей.

Пишем "птицы", а думаем о людях :)

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Professors seeks to understand why birds sing

A better understanding of why birds sing has led David Rothenberg, PhD, a professor in the department of humanities at New Jersey Institute of Technology (NJIT), on a journey into the seemingly disparate worlds of science, poetry and music. The result is the publication this month of Why Birds Sing (Basic Books).

"My book is the first introduction to the world of bird song to combine science, music and poetry to make sense of why birds sing," Rothenberg said.

The book's idea originated with Rothenberg's experiences in 2000 when playing his clarinet along with birds in the National Aviary in Pittsburgh. To his surprise, one bird, a white-crested laughing thrush, responded to his music much more than he had expected. Soon, Rothenberg wanted to know why birds behaved the way they did. He embarked on a journey which led him from ancient writings to the cutting edge of neuroscience,

Why Birds Sing makes good use of Rothenberg's experience teaching courses in science, technology, and society at NJIT. These courses gave him a unique window on which to view his subject. For example, in the 19th century, poets were more accurate than scientists in noting down the rhythms of bird songs. Later, though, in the 20th century, sound recording and computers revolutionized the ability of researchers to print out bird songs and scrutinize the sounds on paper. For Rothenberg, thanks to his unusual teaching and research background, both these facts made sense and indeed were incorporated into the book.

More unusual tidbits abound. The text highlights a 200-page book about a three-note bird song, written in the 1940s. He details a bird that picks up African bird songs on its migratory route . Later this crooner sings the African tunes in the marshes of Europe when it returns in summer.

Examining the field of neuroscience, Rothenberg explains how researchers have discovered that when a canary learns a new song, new neurons appear in his brain.

So why do birds sing. "Because they can and because they must," said Rothenberg. "Songs are used to attract mates and defend territories, but the form is much more than function. Nature is full of beauty, and of music."

David Rothenberg is the author of Sudden Music: Improvisation, Art, Nature (University of Georgia Press, 2001) Blue Cliff Record: Zen Echoes (Codhill Press, New Paltz, NY, 2001), Hand's End: Technology and the Limits of Nature (University of California Press, Berkeley, 1993), Is It Painful to Think? Conversations with Arne Naess (University Press, University of Minnesota, 1992), and Always the Mountains (University of Georgia Press, 2002).

Rothenberg edited The Book of Music and Nature (Wesleyan University Press, 2001), and Parliament of Minds (SUNY Press, 1999) interviews with leading philosophers in conjunction with a public broadcasting television series of the same name, of which he was a co-producer.

Rothenberg is the editor of the Terra Nova book series, published by MIT Press, presenting environmental issues as culture, not only policy. His own writing has been anthologized in The Best Spiritual Writing 1999 edited by Philip Zaleski (Harper San Francisco) and The Soul of Nature: Visions of a Living Earth by M Tobias. His articles have appeared in Parabola, Orion, The Nation, Wired, and other publications.

Source: New Jersey Institute of Technology
Источник: http://www.physorg.com/news3849.html

Коротко о сути:
Проведенное David Rothenberg исследование открывает много новых интересных фактов о пении птиц.
Его невероятно заинтересовало, почему птицы так активно реагировали на его игру на кларнете. (Мой попугай тоже просто обожал слушать (и подпевать) музыку и телевизор :) ).
Еще в 19 веке люди начали подмечать, что в пении птиц присутствует своеобразная рифма, что удалось систематически исследовать только в 20 веке.
Интересно то, что некоторые перелетные птицы возвращаясь из Африки поют в соответствующем "африканском" стиле. Через некоторое же время привыкают к европейскому стилю.
Он утверждает, что птицы поют потому что "они могут и они должны петь". Не только с целью идентифицировать одна другую и свою территорию, но часто мы видим, что вся природа наполнена красотой и музыкой.

Классно :)