The finding provides insights not only into the intricacies of songbird attraction and devotion but also into the way in which the brain develops and responds to social cues, in birds – and humans.
The study is reported in the March 18 issue of PLoS Biology by researchers at University of California, San Francisco.
The discovery paves the way, the researchers say, for studying how complex brain circuits recognize social cues, especially acoustic signals, and how they acquire this capacity -- questions of potential relevance to humans. Such findings could shed light, they say, both on normal development and on disabling disorders of social interactions, such as autism.
Scientists have known that male zebra finches adjust their tune when they have courtship – i.e., copulation – on their minds with either a prospective or lifelong mate. (They are monogamous.) The variation is extremely slight – not a shift in the identity or order of notes, but just in the length, tempo, and variability of presentation. The birds sing faster and produce syllables with less variability in pitch as they dance about the object of their affection. Scientists have chalked this up to evolutionary strategy, but they haven’t actually known if the females detect and discriminate between the tunes.
The current study, reveals that they do. In a set of social behavioral tests, female zebra finches strongly preferred the male zebra finches’ tailored, or “directed” song of courtship to the more variable “undirected” song that males sing when they are on their own.
The researchers also found that female finches have an ear for detail: the female birds were especially sensitive to the degree of variability in the pitch of notes, showing the strongest preferences for directed songs that were least variable in pitch. This finding is provocative, the researchers say, because recent evidence has shown that pitch variability in male song is controlled by a specialized forebrain-basal ganglia circuit known as the anterior forebrain pathway, which plays a role in vocal learning and is similar to forebrain-basal ganglia circuits found in all vertebrate, including humans.
“It is interesting that the neural circuit responsible for the learning of song in juveniles may also be responsible for making the adult male’s song more attractive, and allowing female birds’ preferences to shape the males’ vocal behavior over the course of evolution,” says Sarah C. Woolley, PhD, a postdoctoral fellow in the laboratory of senior author Allison J. Doupe, MD, PhD, a professor of psychiatry and physiology and a member of the Keck Center for Integrative Neuroscience at UCSF.
The results support the idea, Woolley says, that the more stereotyped production of the courtship song is a “performance” state; the bird switches to the more stereotyped directed song because the female finch prefers it.
The scientists carried out the study with two sets of adult female zebra finches – those who had been with a mate for months or even years and those who had been housed with other females once they’d matured. In a series of tests, each was placed in a cage with three chambers lined up in a row. At each end of the cage was a speaker airing a different set of male tunes. Females were allowed to move freely toward the songs they preferred and the scientists recorded the time they spent near speakers broadcasting different types of song. Both mated and non-mated females spent more time near the speaker broadcasting the courtship song.
Interestingly, notes Woolley, females particularly preferred directed song when the singer was familiar. The strongest response was from mated females responding to their mate’s directed song, suggesting, the researchers say, that preferences are further enhanced by experience. Females without partners show a weaker preference for the directed song of an unfamiliar male, suggesting that they have the same perceptual biases as paired females and that their living with a mate makes this fondness stronger. Though the researchers restricted their study to vocal signals, it may be, they say, that female songbirds assessing an unfamiliar male normally rely on cues in addition to song – courtship dancing or beak or feather color.
The researchers subsequently examined the birds’ brains, studying the expression of a gene product known as ZENK, which is associated with memory formation and plasticity. This data revealed that two higher-level auditory areas each responded to a different aspect of song. One brain area responded to whether songs were directed or undirected, while a second area responded to whether songs were familiar or unfamiliar.
“This finding suggests that neurons in this second higher-level auditory region are involved in a kind of social perception,” says Woolley.
Together, Woolley says, the social behavior and neurological data offer insight into a fundamental aspect of social communication – the way in which birdsong is produced and perceived, and the behavioral interplay that connects the two together.
The study was funded by the National Institutes of Health, NARSAD (National Alliance for Research on Schizophrenia and Depression), and the MacArthur-McDonnell Research Network on Early Experience and Brain Development.
UCSF is a leading university dedicated to promoting health worldwide through advanced biomedical research, graduate-level education in the life sciences and health professions, and excellence in patient care.
Jennifer O'Brien | EurekAlert!
Bare bones: Making bones transparent
27.04.2017 | California Institute of Technology
Link Discovered between Immune System, Brain Structure and Memory
26.04.2017 | Universität Basel
More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.
Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...
Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.
"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...
The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.
Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...
The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...
Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.
Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...
20.04.2017 | Event News
18.04.2017 | Event News
03.04.2017 | Event News
27.04.2017 | Life Sciences
27.04.2017 | Physics and Astronomy
27.04.2017 | Earth Sciences