Music in Our Ears: The Biological Bases of Musical Timbre Perception

Timbre is the attribute of sound that allows humans and other animals to distinguish among different sound sources. Studies based on psychophysical judgments of musical timbre, ecological analyses of sound’s physical characteristics as well as machine learning approaches have all suggested that timbre is a multifaceted attribute that invokes both spectral and temporal sound features. Here, we explored the neural underpinnings of musical timbre. We used a neuro-computational framework based on spectro-temporal receptive fields, recorded from over a thousand neurons in the mammalian primary auditory cortex as well as from simulated cortical neurons, augmented with a nonlinear classifier. The model was able to perform robust instrument classification irrespective of pitch and playing style, with an accuracy of 98.7%. Using the same front end, the model was also able to reproduce perceptual distance judgments between timbres as perceived by human listeners. The study demonstrates that joint spectro-temporal features, such as those observed in the mammalian primary auditory cortex, are critical to provide the rich-enough representation necessary to account for perceptual judgments of timbre by human listeners, as well as recognition of musical instruments.

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Rethinking reading: UI study breaks new ground in reading development research

Many educators have long believed that when words differ on only one sound, early readers can learn the rules of phonics by focusing on what is different between the words. This is thought to be a critical gateway to reading words and sentences.

But scientists at the University of Iowa are turning that thinking on its head. A recent study published in Developmental Psychology shows certain kinds of variation in words may help early readers learn better. When children see the same phonics regularities, embedded in words with more variation, they may learn these crucial early reading skills better. What might appear to make learning a more difficult task—learning about letter-sound relationships from words with more variation—actually leads to better learning.

Doctoral student Keith Apfelbaum and associate professors Bob McMurray and Eliot Hazeltine of the Department of Psychology in the UI College of Liberal Arts and Sciences (CLAS) studied 224 first-grade students in the West Des Moines, Iowa school system over a period of three months. The group used a version of an online supplementary curriculum called Access Code.

Access Code was developed by Foundations in Learning, a company founded by Carolyn Brown and Jerry Zimmermann. Brown and Zimmermann earned their doctorates from and are now adjunct faculty in the Department of Communication Sciences and Disorders, also in CLAS. Based on the Varied Practice Model, which helps children master early reading skills like phonics, the research team used Access Code to conduct the study directly in the classroom.

Testosterone regulates solo song of tropical birds

Experiment in females uncovers male hormonal mechanism

In male songbirds of the temperate zone, the concentration of sex hormones is rising in spring, which leads to an increase in song activity during the breeding season. In the tropics, there has been little evidence so far about such a clear relationship between hormonal action and behaviour, which is partly due to a lower degree of seasonal changes of the environment. Researchers of the Max Planck Institute for Ornithology in Seewiesen have now discovered that in duetting African white-browed sparrow weavers, the solo song of dominant males is linked to elevated levels of testosterone. What is more, the male-typical solo song could be activated via testosterone treatment in female birds. The study thus shows a complex relationship between song behaviour and hormone concentration also in a tropical bird species.

'Tree of life' constructed for all living bird species

Scientists have mapped the evolutionary relationships among all 9,993 of the world’s known living bird species. The study, published today in Nature, is an ambitious project that uses DNA-sequence data to create a phylogenetic tree — a branching map of evolutionary relationships among species — that also links global bird speciation rates across space and time.

“This is the first dated tree of life for a class of species this size to be put on a global map,” says study co-author Walter Jetz, an evolutionary biologist at Yale University in New Haven, Connecticut.

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UC Santa Barbara Scientists Learn How to Unlock the Destiny of a Cell: A Gift for the Tin Man?

Scientists have discovered that breaking a biological signaling system in an embryo allows them to change the destiny of a cell. The findings could lead to new ways of making replacement organs.

The discovery was made in the laboratory of Joel H. Rothman, a professor in the Department of Molecular, Cellular, and Developmental Biology at UC Santa Barbara. The studies were reported in the interdisciplinary journal Genes and Development, and were carried out by Ph.D student Nareg Djabrayan, in collaboration with Rothman and two other members of the laboratory, Ph.D student Erica Sommermann and postdoctoral fellow Nathaniel Dudley.

"At some point along the way toward becoming part of a complete individual, cells become destined to choose a particular identity and long-term profession," Rothman noted. "Once a cell chooses who it will be, it locks onto that identity for the remainder of its life."

A cell that is destined to become a heart cell functions exclusively in the heart until it dies, and never chooses later to change jobs by becoming, for example, a brain cell. “If Oz’s wizard possessed the powers he claimed, and had a spare brain lying around, he could switch it to a heart as a gift for the Tin Man. And he could reverse the trick for the Scarecrow,” Rothman said.

Similarly, the researchers have found a way to unlock cells’ destinies and lead them to take on a new profession.

An elephant that speaks Korean

An Asian elephant named Koshik can imitate human speech, speaking words in Korean that can be readily understood by those who know the language. The elephant accomplishes this in a most unusual way: he vocalizes with his trunk in his mouth.

The elephant’s vocabulary consists of exactly five words, researchers report on November 1 in Current Biology, a Cell Press publication. Those include “annyong” (“hello”), “anja” (“sit down”), “aniya” (“no”), “nuo” (“lie down”), and “choah” (“good”). Ultimately, Koshik’s language skills may provide important insights into the biology and evolution of complex vocal learning, an ability that is critical for human speech and music, the researchers say.

"Human speech basically has two important aspects, pitch and timbre," says Angela Stoeger of the University of Vienna. "Intriguingly, the elephant Koshik is capable of matching both pitch and timbre patterns: he accurately imitates human formants as well as the voice pitch of his trainers. This is remarkable considering the huge size, the long vocal tract, and other anatomical differences between an elephant and a human."

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Virtual reality ‘beaming’ technology transforms human-animal interaction

Using cutting-edge virtual reality technology, researchers have ‘beamed’ a person into a rat facility allowing the rat and human to interact with each other on the same scale.

Published in PLOS ONE, the research enables the rat to interact with a rat-sized robot controlled by a human participant in a different location. At the same time, the human participant (who is in a virtual environment) interacts with a human-sized avatar that is controlled by the movements of the distant rat. The authors hope the new technology will be used to study animal behaviour in a completely new way.

Computer scientists at UCL and the University of Barcelona have been working on the idea of ‘beaming’ for some time now, having last year digitally beamed a scientist in Barcelona to London to be interviewed by a journalist.

The researchers define ‘beaming’ as digitally transporting a representation of yourself to a distant place, where you can interact with the people there as if you were there. This is achieved through a combination of virtual reality and teleoperator systems. The visitor to the remote place (the destination) is represented there ideally by a physical robot.

Caffeine’s effect on the brain’s adenosine receptors visualized for the first time

Scans allow researchers to study the link between caffeine and neurodegenerative disorders.

Molecular imaging with positron emission tomography (PET) has enabled scientists for the first time to visualize binding sites of caffeine in the living human brain to explore possible positive and negative effects of caffeine consumption. According to research published in the November issue of The Journal of Nuclear Medicine, PET imaging with F-18-8-cyclopentyl-3-(3-fluoropropyl)-1-propylxanthine (F-18-CPFPX) shows that repeated intake of caffeinated beverages throughout a day results in up to 50 percent occupancy of the brain’s A1 adenosine receptors.

"The effects of caffeine to the human body are generally attributed to the cerebral adenosine receptors. In the human brain the A1 adenosine receptor is the most abundant," said David Elmenhorst, MD, lead author of "Caffeine Occupancy of Human Cerebral A1 Adenosine Receptors: In Vivo Quantification with F-18-CPFPX and PET." "In vitro studies have shown that commonly consumed quantities of caffeine have led to a high A1 adenosine occupancy. Our study aimed to measure the A1 adenosine receptor occupancy with in vivo imaging."

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This is your brain on politics

With the U.S. presidential election just days away, new research from the University of South Carolina provides fresh evidence that choosing a candidate may depend more on our biological make-up than a careful analysis of issues.

That’s because the brains of self-identified Democrats and Republicans are hard-wired differently and may be naturally inclined to hold varying, if not opposing, perceptions and values. The USC study, which analyzed MRI scans of 24 USC students, builds on existing research in the emerging field of political neuroscience.

“The differences are significant and real,” said lead researcher Roger D. Newman-Norlund, an assistant professor of exercise science in the Arnold School of Public Health and the director of USC’s new Brain Simulation Laboratory.

The study focused on the mirror neuron system, a network of brain areas linked to a host of social and emotional abilities. After declaring their political affiliation, The subjects were given questionnaires designed to gauge their attitudes on a range of select political issues. Next, they were given “resting state” MRIs which made it possible to analyze the strength of connections within the mirror neuron system in both the left and right hemispheres of their brains; specifically the inferior frontal gyrus, supramarginal gyrus and angular gyrus.

The results found more neural activity in areas believed to be linked with broad social connectedness in Democrats (friends, the world at-large) and more activity in areas linked with tight social connectedness in the Republicans (family, country). In some ways the study confirms a stereotype about members of the two parties — Democrats tend to be more global and Republicans more America-centric — but it actually runs counter to other recent research indicating Democrats enjoyed a virtual lock on caring for others.