Monkeys “understand” rules underlying language musicality

Many of us have mixed feelings when remembering painful lessons in German or Latin grammar in school. Languages feature a large number of complex rules and patterns: using them correctly makes the difference between something which “sounds good”, and something which does not. However, cognitive biologists at the University of Vienna have shown that sensitivity to very simple structural and melodic patterns does not require much learning, or even being human: South American squirrel monkeys can do it, too.

Language and music are structured systems, featuring particular relationships between syllables, words and musical notes. For instance, implicit knowledge of the musical and grammatical patterns of our language makes us notice right away whether a speaker is native or not. Similarly, the perceived musicality of some languages results from dependency relations between vowels within a word. In Turkish, for example, the last syllable in words like “kaplanlar” or “güller” must “harmonize” with the previous vowels. (Try it yourself: “güllar” requires more movement and does not sound as good as “güller”.)

Similar “dependencies” between words, syllables or musical notes can be found in languages and musical cultures around the world. The biological question is whether the ability to process dependencies evolved in human cognition along with human language, or is rather a more general skill, also present in other animal species who lack language.

Andrea Ravignani, a PhD candidate at the Department of Cognitive Biology at the University of Vienna, and his colleagues looked for this “dependency detection” ability in squirrel monkeys, small arboreal primates living in Central and South America. Inspired by the monkeys’ natural calls and hearing predispositions, the researchers designed a sort of “musical system” for monkeys. These “musical patterns” had overall acoustic features similar to monkeys’ calls, while their structural features mimicked syntactic or phonological patterns like those found in Turkish and many human languages.

Monkeys were first presented with “phrases” containing structural dependencies, and later tested using stimuli either with or without dependencies. Their reactions were measured using the “violation of expectations” paradigm. “Show up at work in your pyjamas, people will turn around and stare at you, while at a slumber party nobody will notice”, explains Ravignani: In other words, one looks longer at something that breaks the “standard” pattern. “This is not about absolute perception, rather how something is categorized and contrasted within a broader system.” Using this paradigm, the scientists found that monkeys reacted more to the “ungrammatical” patterns, demonstrating perception of dependencies. “This kind of experiment is usually done by presenting monkeys with human speech: Designing species-specific, music-like stimuli may have helped the squirrel monkeys’ perception”, argues primatologist and co-author Ruth Sonnweber.

"Our ancestors may have already acquired this simple dependency-detection ability some 30 million years ago, and modern humans would thus share it with many other living primates. Mastering basic phonological patterns and syntactic rules is not an issue for squirrel monkeys: the bar for human uniqueness has to be raised", says Ravignani: "This is only a tiny step: we will keep working hard to unveil the evolutionary origins and potential connections between language and music".

Menstrual Cycle Influences Concussion Outcomes

Researchers found that women injured during the two weeks leading up to their period (the premenstrual phase) had a slower recovery and poorer health one month after injury compared to women injured during the two weeks directly after their period or women taking birth control pills.

The University of Rochester study was published today in the Journal of Head Trauma Rehabilitation. If confirmed in subsequent research, the findings could alter the treatment and prognosis of women who suffer head injuries from sports, falls, car accidents or combat.

Several recent studies have confirmed what women and their physicians anecdotally have known for years: Women experience greater cognitive decline, poorer reaction times, more headaches, extended periods of depression, longer hospital stays and delayed return-to-work compared to men following head injury. Such results are particularly pronounced in women of childbearing age; girls who have not started their period and post-menopausal women have outcomes similar to men.

Few studies have explored why such differences occur, but senior author Jeffrey J. Bazarian, M.D., M.P.H. says it stands to reason that sex hormones such as estrogen and progesterone, which are highest in women of childbearing age, may play a role.

“I don’t think doctors consider menstrual history when evaluating a patient after a concussion, but maybe we should,” noted Bazarian, associate professor of Emergency Medicine at the University of Rochester School of Medicine and Dentistry who treats patients and conducts research on traumatic brain injury and long-term outcomes among athletes. “By taking into account the stage of their cycle at the time of injury we could better identify patients who might need more aggressive monitoring or treatment. It would also allow us to counsel women that they’re more – or less – likely to feel poorly because of their menstrual phase.”

Although media coverage tends to focus on concussions in male professional athletes, studies suggest that women have a higher incidence of head injuries than men playing sports with similar rules, such as ice hockey, soccer and basketball. Bazarian estimates that 70 percent of the patients he treats in the URMC Sport Concussion Clinic are young women. He believes the number is so high because they often need more follow-up care. In his experience, soccer is the most common sport leading to head injuries in women, but lacrosse, field hockey, cheerleading, volleyball and basketball can lead to injuries as well.

Sex hormone levels often change after a head injury, as women who have suffered a concussion and subsequently missed one or more periods can attest. According to Kathleen M. Hoeger, M.D., M.P.H., study co-author and professor of Obstetrics and Gynecology at the University of Rochester School of Medicine and Dentistry, any stressful event, like a hit to the head, can shut down the pituitary gland in the brain, which is the body’s hormone generator. If the pituitary doesn’t work, the level of estrogen and progesterone would drop quickly.  

According to Bazarian, progesterone is known to have a calming effect on the brain and on mood. Knowing this, his team came up with the “withdrawal hypothesis”: If a woman suffers a concussion in the premenstrual phase when progesterone levels are naturally high, an abrupt drop in progesterone after injury produces a kind of withdrawal which either contributes to or worsens post concussive symptoms like headache, nausea, dizziness and trouble concentrating. This may be why women recover differently than men, who have low pre-injury levels of the hormone.     

Hoeger and Bazarian tested their theory by recruiting144 women ages 18 to 60 who arrived within four hours of a head hit at five emergency departments in upstate New York and one in Pennsylvania. Participants gave blood within six hours of injury and progesterone level determined the menstrual cycle phase at the time of injury. Based on the results, participants fell into three groups: 37 in the premenstrual/high progesterone group; 72 in the low progesterone group (progesterone is low in the two weeks directly after a period); and 35 in the birth control group based on self-reported use.

One month later, women in the premenstrual/high progesterone group were twice as likely to score in a worse percentile on standardized tests that measure concussion recovery and quality of life – as defined by mobility, self-care, usual activity, pain and emotional health – compared to women in the low progesterone group. Women in the premenstrual/high progesterone group also scored the lowest (average 65) on a health rating scale that went from 0, being the worst health imaginable, to 100, being the best. Women in the birth control group had the highest scores (average 77).

“If you get hit when progesterone is high and you experience a steep drop in the hormone, this is what makes you feel lousy and causes symptoms to linger,” said Bazarian. “But, if you are injured when progesterone is already low, a hit to the head can’t lower it any further, so there is less change in the way you feel.”

The team suspected that women taking birth control pills, which contain synthetic hormones that mimic the action of progesterone, would have similar outcomes to women injured in the low progesterone phase of their cycle. As expected, there was no clear difference between these groups, as women taking birth control pills have a constant stream of sex hormones and don’t experience a drop following a head hit, so long as they continue to take the pill.    

“Women who are very athletic get several benefits from the pill; it protects their bones and keeps their periods predictable,” noted Hoeger. “If larger studies confirm our data, this could be one more way in which the pill is helpful in athletic women, especially women who participate in sports like soccer that present lots of opportunities for head injuries.”

In addition to determining menstrual cycle phase at the time of injury, Bazarian plans to scrutinize a woman’s cycles after injury to make sure they are not disrupted. If they are, the woman should make an appointment with her gynecologist to discuss the change.

Literacy depends on nurture, not nature

A University at Buffalo education professor has sided with the environment in the timeless “nurture vs. nature” debate after his research found that a child’s ability to read depends mostly on where that child is born, rather than on his or her individual qualities.

“Individual characteristics explain only 9 percent of the differences in children who can read versus those who cannot,” says Ming Ming Chiu, lead author of an international study that explains this connection and a professor in the Department of Learning and Instruction in UB’s Graduate School of Education. 

“In contrast, country differences account for 61 percent and school differences account for 30 percent,” Chiu says.

Therefore, he concludes, the country in which a child is born largely determines whether he or she will have at least basic reading skills. It’s clearly a case where “nurture” — the environment and surroundings of the child — is more important than “nature” — the child’s inherited, individual qualities, according to Chiu.

More than 99 percent of fourth-graders in the Netherlands can read, but only 19 percent of fourth-graders in South Africa can read, Chiu notes.

“Although the richest countries typically have high literacy rates exceeding 97 percent,” he says, “some rich countries, such as Qatar and Kuwait, have low literacy rates — 33 percent and 28 percent, respectively.”

The study, “Ecological, Psychological and Cognitive Components of Reading Difficulties: Testing the Component Model of Reading in Fourth-graders Across 38 Countries,” analyzed reading test scores of 186,725 fourth-graders from 38 countries, including more than 4,000 children from the U.S. Chiu and co-authors Catherine McBride-Chang of the Chinese University of Hong Kong and Dan Lin of the Hong Kong Institute of Education published the study in the winter 2013 issue of the Journal of Learning Disabilities.

The educators used data from the Organization for Economic Cooperation and Development’s Program for International Student Assessment.

Besides showing that the country of origin was a better predictor of reading skills than individual traits, the study also showed that other attributes at the child, school and country levels were all related to reading.

First, girls were more likely than boys to have basic reading skills, Chiu says. Children with greater early-literacy skills, better attitudes about reading or greater self-confidence in their reading ability also were more likely to have strong basic reading skills.

“Children were more likely to have basic reading skills if they were from privileged families, as measured through socioeconomic status, number of books at home and parent attitudes about reading,” says Chiu. “Also, children attending schools with better school climate and more resources were more likely to have basic reading skills.

“Our U.S. culture values ‘can-do’ individualism, but we forget how much depends on being lucky enough to be born in the right place,” he says.

Your Brain Sees Things You Don’t

University of Arizona doctoral degree candidate Jay Sanguinetti has authored a new study, published online in the journal Psychological Science, that indicates that the brain processes and understands visual input that we may never consciously perceive.

The finding challenges currently accepted models about how the brain processes visual information.

A doctoral candidate in the UA’s Department of Psychology in the College of Science, Sanguinetti showed study participants a series of black silhouettes, some of which contained meaningful, real-world objects hidden in the white spaces on the outsides.

Saguinetti worked with his adviser Mary Peterson, a professor of psychology and director of the UA’s Cognitive Science Program, and with John Allen, a UA Distinguished Professor of psychology, cognitive science and neuroscience, to monitor subjects’ brainwaves with an electroencephalogram, or EEG, while they viewed the objects.

"We were asking the question of whether the brain was processing the meaning of the objects that are on the outside of these silhouettes," Sanguinetti said. "The specific question was, ‘Does the brain process those hidden shapes to the level of meaning, even when the subject doesn’t consciously see them?"

The answer, Sanguinetti’s data indicates, is yes.

Study participants’ brainwaves indicated that even if a person never consciously recognized the shapes on the outside of the image, their brains still processed those shapes to the level of understanding their meaning.

"There’s a brain signature for meaningful processing," Sanguinetti said. A peak in the averaged brainwaves called N400 indicates that the brain has recognized an object and associated it with a particular meaning.

"It happens about 400 milliseconds after the image is shown, less than a half a second," said Peterson. "As one looks at brainwaves, they’re undulating above a baseline axis and below that axis. The negative ones below the axis are called N and positive ones above the axis are called P, so N400 means it’s a negative waveform that happens approximately 400 milliseconds after the image is shown."

The presence of the N400 peak indicates that subjects’ brains recognize the meaning of the shapes on the outside of the figure.

"The participants in our experiments don’t see those shapes on the outside; nonetheless, the brain signature tells us that they have processed the meaning of those shapes," said Peterson. "But the brain rejects them as interpretations, and if it rejects the shapes from conscious perception, then you won’t have any awareness of them."

"We also have novel silhouettes as experimental controls," Sanguinetti said. "These are novel black shapes in the middle and nothing meaningful on the outside."

The N400 waveform does not appear on the EEG of subjects when they are seeing truly novel silhouettes, without images of any real-world objects, indicating that the brain does not recognize a meaningful object in the image.

"This is huge," Peterson said. "We have neural evidence that the brain is processing the shape and its meaning of the hidden images in the silhouettes we showed to participants in our study."

The finding leads to the question of why the brain would process the meaning of a shape when a person is ultimately not going to perceive it, Sanguinetti said.

"The traditional opinion in vision research is that this would be wasteful in terms of resources," he explained. "If you’re not going to ultimately see the object on the outside why would the brain waste all these processing resources and process that image up to the level of meaning?"

"Many, many theorists assume that because it takes a lot of energy for brain processing, that the brain is only going to spend time processing what you’re ultimately going to perceive," added Peterson. "But in fact the brain is deciding what you’re going to perceive, and it’s processing all of the information and then it’s determining what’s the best interpretation."

"This is a window into what the brain is doing all the time," Peterson said. "It’s always sifting through a variety of possibilities and finding the best interpretation for what’s out there. And the best interpretation may vary with the situation."

Our brains may have evolved to sift through the barrage of visual input in our eyes and identify those things that are most important for us to consciously perceive, such as a threat or resources such as food, Peterson suggested.

In the future, Peterson and Sanguinetti plan to look for the specific regions in the brain where the processing of meaning occurs.

"We’re trying to look at exactly what brain regions are involved," said Peterson. "The EEG tells us this processing is happening and it tells us when it’s happening, but it doesn’t tell us where it’s occurring in the brain."

"We want to look inside the brain to understand where and how this meaning is processed," said Peterson.

Images were shown to Sanguinetti’s study participants for only 170 milliseconds, yet their brains were able to complete the complex processes necessary to interpret the meaning of the hidden objects.

"There are a lot of processes that happen in the brain to help us interpret all the complexity that hits our eyeballs," Sanguinetti said. "The brain is able to process and interpret this information very quickly."

Sanguinetti’s study indicates that in our everyday life, as we walk down the street, for example, our brains may recognize many meaningful objects in the visual scene, but ultimately we are aware of only a handful of those objects.

The brain is working to provide us with the best, most useful possible interpretation of the visual world, Sanguinetti said, an interpretation that does not necessarily include all the information in the visual input.

What are you scared of?

What do bullies and sex have in common? Based on work by scientists at the European Molecular Biology Laboratory (EMBL) in Monterotondo, Italy, it seems that the same part of the brain reacts to both. In a study published today in Nature Neuroscience, the researchers found that – at least in mice – different types of fear are processed by different groups of neurons, even if the animals act out those fears in the same way. The findings could have implications for addressing phobias and panic attacks in humans.

“We found that there seems to be a circuit for handling fear of predators – which has been described anatomically as a kind of defence circuit – but fear of members of the same species uses the reproductive circuit instead,” says Bianca Silva, who carried out the work, “and fear of pain goes through yet another part of the brain.” 

Working in the lab of Cornelius Gross at EMBL, Silva exposed mice to three threats: another mouse (chosen for being particularly aggressive), a rat (the mouse’s natural predator) or a mild electric shock to the feet. The mice showed the same typical fearful behaviours – running away, freezing – in response to all threats, but their brains painted a different picture. When the scientists mapped the brain activity of mice exposed to the aggressive mouse and the rat, they saw that different parts of a region called the ventromedial hypothalamus (VMH) ‘lit up’ depending on the threat. Fear of the mouse seemed to activate the bottom and sides of the VMH, while fear of the rat seemed to be processed by the VMH’s central and upper areas. This was confirmed when the scientists used drugs to block only the neurons in those ‘rat fear’ areas: mice were no longer afraid of the rat, but were still afraid of the mouse, showing that mice need this brain circuit specifically to process fear of predators.

The human brain has similar circuits, and we too experience different kinds of fear, so the results hint at the possibility of developing more efficient treatments for specific phobias or panic attacks, by targeting only the relevant region of the brain.

For their part, the EMBL scientists plan to probe these fears further. 

“What we’re interested in, in the long-run, is if these results represent a kind of mental state,” says Cornelius Gross, who led the work. “If so, mice should be able to be in that state without expressing it in their behaviour – do they re-live that fear, for example? These are not easy questions to ask in the mouse, but we’re looking into them.”

Gross’s lab are also looking at how these different fears – and the neural circuits that process them – may have evolved. Working with Detlev Arendt’s group at EMBL Heidelberg, they have discovered a similar brain region in a marine worm thought to closely resemble our ancestors from 600 million years ago. Now the team is exploring the possibility that this represents an ancestral core fear circuit that those ancestors handed down to us all, from worms to man.

A longitudinal study of grapheme-color synaesthesia in childhood

What colour is H? Is 4 brighter than 9? For most people these questions might seem baffling, but not for people with grapheme-color synesthesia.

In the first long-term childhood study on grapheme-color synesthesia, researchers followed 80 children to determine when and how associations between graphemes and colors develop. The latest results are published in the open-access journal Frontiers in Human Neuroscience.

Grapheme-color synesthesia is a harmless, alternative form of perception caused by subtle differences in the brain – possibly, stronger connections between centers for language and color – that give letters and numbers their phantom colors. It is passed down from parent to child in around 1 to 2% of the population.

In the present study, a group of synesthete children was tested three times between 6 and 10 years old. Each child was presented with 36 graphemes – the letters A to Z and digits 0 to 9 – and asked to choose the ‘best’ of 13 colors for each.

Children with grapheme-color synesthesia had already developed strong associations for around 30% of graphemes at 6 years old. At 7 years old, the same children had associations for around 50% of graphemes, and this increased to 70% of graphemes at 10 years old. The synesthete children were consistent in their choices over this 4-year period. Three children who were synesthetes at ages 6 to 7 were no longer so at 10 years old, indicating that the condition spontaneously disappears in some children as they grow older.

"This repeated testing of child synesthetes in real time allowed us to see for the first time that synesthetic colours emerge slowly during childhood, building up an incremental inventory of colorful letters and numbers," says Dr. Simner, a cognitive neuropsychologist who specializes in synesthesia, from the University of Edinburgh, UK.

The researchers’ next challenge is to determine how changes in the intensity of synesthesia - as strengthening or loss with increasing age - can be explained from changes in the organization of the brain.

(Image: Shutterstock)