Led by James Goodson, associate professor of psychology and neuroscience, and detailed in this week's early online edition of the Proceedings of the National Academy of Sciences, the research demonstrates that vasotocin neurons in the medial extended amygdala respond differently to social cues in birds that live in colonies compared to their more solitary cousins.
Vasotocin neurons appear, according to the study, to selectively promote positive affiliation. The gregarious species also have greater numbers of the neurons and their baseline activity is about twice as high, putting the birds in a kind of perpetual "social mood."
"These findings," Goodson said, "address the fundamental question of sociality: Why are some animal species highly social while others seem to have little or no tolerance for others?
"And while the observations were made in birds, they should apply to many other animals, including humans, since the cells are present in almost all vertebrates and the brain circuits that regulate the basic forms of social behavior are strikingly similar," he said.
Goodson worked with birds because, with more than 9,200 species and "a dazzling array of social structures," they offer opportunities to study groups of species that differ only in one aspect of social behavior, making it possible to attribute that dimension – in this case, sociality – to differences in a particular brain function.
Traveling as far as South Africa to collect the appropriate birds, Goodson focused on five species of closely related waxbills and finches: the melba finch, the violet-eared waxbill, the Angolan blue waxbill, the spice finch and the zebra finch. All the birds live in similar habitats, are monogamous pair bonders, exhibit biparental care and breed depending on rainfall, but where the melba finch and the violet-eared waxbill are territorial and live in male-female pairs, the spice and zebra finch establish colonies of about 100. The Angolan blue waxbill is an intermediate species, whose groups range from 8 to 40.
Goodson and lab assistant Yiwei Wang stained and examined the birds' brain tissue for a protein known as "Fos" (a cellular marker of brain activity commonly used in neuroscience) specifically within neurons that produce vasotocin. Vasotocin and its equivalent in mammals, vasopressin, are neurochemicals that are known to be involved in a variety of social behaviors, from social recognition to monogamous pair-bonding.
After the birds had viewed a same-sex member of their own species through a wire barrier, the researchers found that activity within one group of vasotocin neurons, in the medial extended amygdala, had increased significantly in the gregarious species. In the asocial species, however, it had decreased.
Goodson and Wang wondered if the results of the same-sex exposure pointed to a specialization of the vasotocin neurons – such that their activity increases in response to positive social situations that normally promote affiliation in a given species rather than those that provoke avoidance or attack. To test the idea, they conducted two additional experiments.
In the first, territorial violet-eared waxbills were exposed to their pair bond partner. As predicted, and in contrast to the response seen after exposure to a bird of the same sex (a negative situation for a territorial, asocial species), the activity of vasotocin neurons increased dramatically in response to this positive scenario.
In the second experiment, highly social zebra finches were placed in a mate-competition situation. Subjects were either allowed to court or were prevented from doing so by a bully. Activity in the vasotocin neurons went up after the positive experience but not after the negative experience of being bullied, supporting the idea that the cells are selectively sensitive.
"In sum," Goodson said, "these vasotocin neurons increase their activity in response to positive social stimuli, and the neurons appear to have evolved in relation to sociality, so that the gregarious species have more vasotocin neurons with higher baseline levels of activity than do the asocial species."
Vasotocin neurons may account for "personality" differences between individuals as well. In related work that has yet to be published, Goodson said, he has observed differences in the number and activity of the neurons in zebra finches that are either duds or studs when it comes to courtship behavior.
Goodson also suspects that the neurons play an analogous role in human social behavior – though we are long way from being able to apply the findings and turn a misanthrope into a party animal.
Inga Kiderra | EurekAlert!
Multi-institutional collaboration uncovers how molecular machines assemble
02.12.2016 | Salk Institute
Fertilized egg cells trigger and monitor loss of sperm’s epigenetic memory
02.12.2016 | IMBA - Institut für Molekulare Biotechnologie der Österreichischen Akademie der Wissenschaften GmbH
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.
The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...
Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water
In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...
The efficiency of power electronic systems is not solely dependent on electrical efficiency but also on weight, for example, in mobile systems. When the weight of relevant components and devices in airplanes, for instance, is reduced, fuel savings can be achieved and correspondingly greenhouse gas emissions decreased. New materials and components based on gallium nitride (GaN) can help to reduce weight and increase the efficiency. With these new materials, power electronic switches can be operated at higher switching frequency, resulting in higher power density and lower material costs.
Researchers at the Fraunhofer Institute for Solar Energy Systems ISE together with partners have investigated how these materials can be used to make power...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
02.12.2016 | Medical Engineering
02.12.2016 | Agricultural and Forestry Science
02.12.2016 | Physics and Astronomy