UCSF Team Reveals How the Brain Recognizes Speech Sounds

UC San Francisco researchers are reporting a detailed account of how speech sounds are identified by the human brain, offering an unprecedented insight into the basis of human language.

The finding, they said, may add to our understanding of language disorders, including dyslexia.

Scientists have known for some time the location in the brain where speech sounds are interpreted, but little has been discovered about how this process works.

Now, in the Jan. 30 edition of Science Express, the fast-tracked online version of the journal Science, the UCSF team reports that the brain does not respond to the individual sound segments known as phonemes – such as the b sound in “boy” – but is instead exquisitely tuned to detect simpler elements, which are known to linguists as “features.”

This organization may give listeners an important advantage in interpreting speech, the researchers said, since the articulation of phonemes varies considerably across speakers, and even in individual speakers over time.

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Head first: reshaping how traumatic brain injury is treated

Traumatic brain injury affects 10 million people a year worldwide and is the leading cause of death and disability in children and young adults. A new study will identify how to match treatments to patients, to achieve the best possible outcome for recovery.

The iPod in the head: How the brain processes musical hallucinations

Sufferers persistently perceive music, as if they were hearing it with their ears, when no music is actually being played. Initially they often mistake the experience for actual music playing and while musical hallucinations can occasionally be a symptom of a neurological or psychiatric disorder, it is usually caused by hearing loss in people who are in normal physical and mental health.

Dr Sukhbinder Kumar from the Institute of Neuroscience at Newcastle University, lead author of the paper published in Cortex said: “We found that a network of brain areas, that are usually involved in processing of melodies and retrieval of memory of music, were particularly active during hallucinations of music in the absence of any sound or music being played externally.”

Nearly one in ten people suffer from tinnitus which is technically an auditory hallucination, in which tones or buzzing noises are heard following hearing loss. However in a small number of people with hearing loss these hallucinations take the form of music, but until now the brain mechanisms underlying this process were poorly understood.

This study by researchers at Newcastle University and University College London and funded by the Wellcome Trust has looked in depth at one sufferer of the condition and pinpointed the regions of the brain involved in producing the hallucinations. These findings could lead to a better understanding of the condition and possibly treatments in the future.

Musical hallucination

Sylvia, 69, a maths teacher who is also a musician with perfect pitch, started to go deaf about 20 years ago after a viral infection. Then about eleven years later she experienced a sudden acute hearing loss and severe tinnitus and her musical hallucinations developed after this. Due to her musical knowledge Sylvia was able to notate what she was hearing.

Initially the condition was irritating and affected Sylvia’s sleep, but she learnt to live with it. “I did everything I could to get rid of them but they persisted, always in a minor key and therefore a bit depressing,” she said.

“Eventually the number of notes increased until they seemed to be parts of tunes. One day I recognized something and, once I had done so, more and more phrases from classical music appeared in my brain.”

Among the pieces of music that Sylvia was hearing in her hallucinations was Gilbert and Sullivan’s HMS Pinafore, as well as music by Bach. Amazingly Sylvia found that by playing music herself, she was able to alter the music in her hallucinations.

“I can change the hallucination playing in my head to the music I am practising. This is particularly the case with the music of Bach - the hallucination will pause and then a whole page will start to play in my head, gradually curtailing itself until just a phrase remains and is repeated.  That might then repeat a thousand times a day. It is as if I have my own internal ipod.”

Sylvia’s experience is fairly typical, though the condition occurs just as often in non-musicians, and sometimes starts abruptly rather than slowly developing as in her case.

How we hear

As Sylvia’s hallucinations could be manipulated by playing an external piece of music that allowed the researchers to understand what was happening in her brain during hallucinations. They first identified pieces of music that suppressed her hallucinations and these pieces were then played to her while her brain activity was being monitored using magnetoencephalography MEG), which measures magnetic fields around the scalp as the brain processes information.

During normal perception of music what we actually ‘hear’ is a complex interplay of the sound entering the ear and our brain’s interpretations and predictions. Normally the strength and quality of the input from the ear is so high that it dominates what we actually perceive however the brain fills in the gaps when the ears do not provide enough input.

“With hearing loss, as in Sylvia’s case, the signal from the ear becomes weak and noisy, like a poorly-tuned radio. The brain’s predictive mechanisms therefore have to work very hard to make sense of what we are hearing. What we have found is that these processes sometimes end up running away with themselves to cause hallucinations,” said author Dr William Sedley also of Newcastle University.

Dr Kumar added: “This also explains why listening to an external piece of music suppresses hallucinations. When external music is playing the signal entering her brain is much stronger and more reliable, which constrains the aberrant communication going on in the brain areas during hallucinations.”

This new understanding of musical hallucinations may provide better treatment in the future as Newcastle University’s Professor Tim Griffiths, professor of Cognitive Neurology who lead the study explained: “It might be possible to disrupt the abnormal communication between the brain areas using brain stimulation, or to use pharmacological treatments to disrupt chemical transmitters that drive communication between them.

“Better hearing aids also appear to help suppress hallucinations, so we would advise people experiencing musical hallucinations to seek medical attention, if for nothing more than to ensure they have the best available hearing aids.”

Dr John Williams, Head of Neuroscience and Mental Health at the Wellcome Trust, says: “This case is extremely fascinating, but the condition is relatively rare. However, it is unusual cases such as this that can give us profound insights into how the brain works and, one hopes, lead to potential new treatments to improve the patient’s life.”

Study Examines the Development of Children’s Prelife Reasoning

Most people, regardless of race, religion or culture, believe they are immortal. That is, people believe that part of themselves–some indelible core, soul or essence–will transcend the body’s death and live forever.  But what is this essence?  Why do we believe it survives?  And why is this belief so unshakable?

A new Boston University study led by postdoctoral fellow Natalie Emmons and published in the January 16, 2014 online edition of Child Development sheds light on these profound questions by examining children’s ideas about “prelife,” the time before conception. By interviewing 283 children from two distinct cultures in Ecuador, Emmons’s research suggests that our bias toward immortality is a part of human intuition that naturally emerges early in life. And the part of us that is eternal, we believe, is not our skills or ability to reason, but rather our hopes, desires and emotions. We are, in fact, what we feel.

Emmons’ study fits into a growing body of work examining the cognitive roots of religion. Although religion is a dominant force across cultures, science has made little headway in examining whether religious belief–such as the human tendency to believe in a creator–may actually be hard-wired into our brains.

“This work shows that it’s possible for science to study religious belief,” said Deborah Kelemen, an Associate Professor of Psychology at Boston University and co-author of the paper. “At the same time, it helps us understand some universal aspects of human cognition and the structure of the mind.”

Most studies on immortality or “eternalist” beliefs have focused on people’s views of the afterlife. Studies have found that both children and adults believe that bodily needs, such as hunger and thirst, end when people die, but mental capacities, such as thinking or feeling sad, continue in some form.  But these afterlife studies leave one critical question unanswered: where do these beliefs come from? Researchers have long suspected that people develop ideas about the afterlife through cultural exposure, like television or movies, or through religious instruction. But perhaps, thought Emmons, these ideas of immortality actually emerge from our intuition.  Just as children learn to talk without formal instruction, maybe they also intuit that part of their mind could exist apart from their body.

Emmons tackled this question by focusing on “prelife,” the period before conception, since few cultures have beliefs or views on the subject. “By focusing on prelife, we could see if culture causes these beliefs to appear, or if they appear spontaneously,” said Emmons.

“I think it’s a brilliant idea,” said Paul Bloom, a Professor of Psychology and Cognitive Science at Yale who was not involved with the study. “One persistent belief is that children learn these ideas through school or church. That’s what makes the prelife research so cool. It’s a very clever way to get at children’s beliefs on a topic where they aren’t given answers ahead of time.”

Emmons interviewed children from an indigenous Shuar village in the Amazon Basin of Ecuador. She chose the group because they have no cultural prelife beliefs, and she suspected that indigenous children, who have regular exposure to birth and death through hunting and farming, would have a more rational, biologically-based view of the time before they were conceived. For comparison, she also interviewed children from an urban area near Quito, Ecuador. Most of the urban children were Roman Catholic, a religion that teaches that life begins only at conception. If cultural influences were paramount, reasoned Emmons, both urban and indigenous children should reject the idea of life before birth.

Emmons showed the children drawings of a baby, a young woman, and the same woman while pregnant, then asked a series of questions about the child’s abilities, thoughts and emotions during each period: as babies, in the womb, and before conception.

The results were surprising.  Both groups gave remarkably similar answers, despite their radically different cultures. The children reasoned that their bodies didn’t exist before birth, and that they didn’t have the ability to think or remember. However, both groups also said that their emotions and desires existed before they were born. For example, while children generally reported that they didn’t have eyes and couldn’t see things before birth, they often reported being happy that they would soon meet their mother, or sad that they were apart from their family.

“They didn’t even realize they were contradicting themselves,” said Emmons. “Even kids who had biological knowledge about reproduction still seemed to think that they had existed in some sort of eternal form.  And that form really seemed to be about emotions and desires.”

Why would humans have evolved this seemingly universal belief in the eternal existence of our emotions? Emmons said that this human trait might be a by-product of our highly developed social reasoning. “We’re really good at figuring out what people are thinking, what their emotions are, what their desires are,” she said. We tend to see people as the sum of their mental states, and desires and emotions may be particularly helpful when predicting their behavior. Because this ability is so useful and so powerful, it flows over into other parts of our thinking. We sometimes see connections where potentially none exist, we hope there’s a master plan for the universe, we see purpose when there is none, and we imagine that a soul survives without a body.

These ideas, while nonscientific, are natural and deep-seated. “I study these things for a living but even find myself defaulting to them. I know that my mind is a product of my brain but I still like to think of myself as something independent of my body,” said Emmons.

“We have the ability to reflect and reason scientifically, and we have the ability to reason based on our gut and intuition,” she added. “And depending on the situation, one may be more useful than the other.”

Honesty beats dishonesty for making you feel good

A University of Toronto report based on two neural imaging studies that monitored brain activity has found a reward given for telling the truth gives people greater satisfaction than the same reward given for deceit.

These studies were published recently in the neuroscience journals Neuropsychologia and NeuroImage.

"Our findings together show that people typically find truth-telling to be more rewarding than lying in different types of deceptive situations,” said Professor Kang Lee,whose research is funded in part by the Social Sciences and Humanities Research Council.

The findings are based on two studies of Chinese participants using a new neuroimaging method called near-infrared spectroscopy. The studies are among the first to address the question of whether lying makes people feel better or worse than telling the truth.

The studies explored two different types of deception. In first-order deception, the recipient does not know the deceiver is lying. In second-order deception, the deceivers are fully aware that the recipient knows their intention, such as bluffing in poker.

The researchers were surprised to find that a liar’s cortical reward system was more active when a reward was gained through truth-telling than lying. This was true in both types of deception.

Researchers also found that in both types of deception, telling a lie produced greater brain activations than telling the truth in the frontal lobe, suggesting lying is cognitively more taxing than truth-telling and uses more neural resources.

The researchers hope this study will advance understanding of the neural mechanisms underlying lying, a ubiquitous and frequent human behaviour, and help to diagnose pathological liars who may have different neural responses when lying or telling the truth.

‘Love hormone’ oxytocin carries unexpected side effect

The love hormone, the monogamy hormone, the cuddle hormone, the trust-me drug: oxytocin has many nicknames. That’s because this naturally occurring human hormone has recently been shown to help people with autism and schizophrenia overcome social deficits.

As a result, certain psychologists prescribe oxytocin off-label, to treat mild social unease in patients who don’t suffer from a diagnosed disorder. But that’s not such a good idea, according to researchers at Concordia’s Centre for Research in Human Development. Their recent study — published in Emotion, a journal of the American Psychological Association — shows that in healthy young adults, too much oxytocin can actually result in oversensitivity to the emotions of others.

With the help of psychology professor Mark Ellenbogen, PhD candidates Christopher Cardoso and Anne-Marie Linnen recruited 82 healthy young adults who showed no signs of schizophrenia, autism or related disorders. Half of the participants were given measured doses of oxytocin, while the rest were offered a placebo.

The participants then completed an emotion identification accuracy test in which they compared different facial expressions showing various emotional states. As expected, the test subjects who had taken oxytocin saw greater emotional intensity in the faces they were rating.

“For some, typical situations like dinner parties or job interviews can be a source of major social anxiety,” says Cardoso, the study’s lead author. “Many psychologists initially thought that oxytocin could be an easy fix in overcoming these worries. Our study proves that the hormone ramps up innate social reasoning skills, resulting in an emotional oversensitivity that can be detrimental in those who don’t have any serious social deficiencies.”

As Cardoso explains, “If your potential boss grimaces because she’s uncomfortable in her chair and you think she’s reacting negatively to what you’re saying, or if the guy you’re talking to at a party smiles to be friendly and you think he’s coming on to you, it can lead you to overreact — and that can be a real problem. That’s why we’re cautioning against giving oxytocin to people who don’t really need it.”

Ultimately, however, oxytocin does have the potential to help people with diagnosed disorders like autism to overcome social deficits.

But, says Cardoso, “The potential social benefits of oxytocin in most people may be countered by unintended negative consequences, like being too sensitive to emotional cues in everyday life.”

Forget about forgetting – The elderly know more and use it better

What happens to our cognitive abilities as we age? If your think our brains go into a steady decline, research reported this week in the Journal Topics in Cognitive Science may make you think again. The work, headed by Dr. Michael Ramscar of Tübingen University, takes a critical look at the measures usually thought to show that our cognitive abilities decline across adulthood. Instead of finding evidence of decline, the team discovered that most standard cognitive measures, which date back to the early twentieth century, are flawed. “The human brain works slower in old age,” says Ramscar, “but only because we have stored more information over time.”

Computers were trained, like humans, to read a certain amount each day, and to learn new things. When the researchers let a computer “read” only so much, its performance on cognitive tests resembled that of a young adult. But if the same computer was exposed to the experiences we might encounter over a lifetime – with reading simulated over decades – its performance now looked like that of an older adult. Often it was slower, but not because its processing capacity had declined. Rather, increased “experience” had caused the computer’s database to grow, giving it more data to process – which takes time.

Technology now allows researchers to make quantitative estimates of the number of words an adult can be expected to learn across a lifetime, enabling the Tübingen team to separate the challenge that increasing knowledge poses to memory from the actual performance of memory itself. “Imagine someone who knows two people’s birthdays and can recall them almost perfectly. Would you really want to say that person has a better memory than a person who knows the birthdays of 2000 people, but can ‘only’ match the right person to the right birthday nine times out of ten?” asks Ramscar.

The answer appears to be “no.” When Ramscar’s team trained their computer models on huge linguistic datasets, they found that standardized vocabulary tests, which are used to take account of the growth of knowledge in studies of ageing, massively underestimate the size of adult vocabularies. It takes computers longer to search databases of words as their sizes grow, which is hardly surprising but may have important implications for our understanding of age-related slowdowns. The researchers found that to get their computers to replicate human performance in word recognition tests across adulthood, they had to keep their capacities the same. “Forget about forgetting,” explained Tübingen researcher Peter Hendrix, “if I wanted to get the computer to look like an older adult, I had to keep all the words it learned in memory and let them compete for attention.”

The research shows that studies of the problems older people have with recalling names suffer from a similar blind spot: there is a far greater variety of given names today than there were two generations ago. This cultural shift toward greater name diversity means the number of different names anyone learns over their lifetime has increased dramatically. The work shows how this makes locating a name in memory far harder than it used to be. Even for computers.

Ramscar and his colleagues’ work provides more than an explanation of why, in the light of all the extra information they have to process, we might expect older brains to seem slower and more forgetful than younger brains. Their work also shows how changes in test performance that have been taken as evidence for declining cognitive abilities in fact demonstrates older adults’ greater mastery of the knowledge they have acquired.

Take “paired-associate learning,” a commonly used cognitive test that involves learning to connect words like “up” to “down” or “necktie” to “cracker” in memory. Using Big Data sets to quantify how often different words appear together in English, the Tuebingen team show that younger adults do better when asked to learn to pair “up” with “down” than “necktie” and “cracker” because “up” and “down” appear in close proximity to one another more frequently. However, whereas older adults also understand which words don’t usually go together, young adults notice this less. When the researchers examined performance on this test across a range of word pairs that go together more and less in English, they found older adult’s scores to be far more closely attuned to the actual information in hundreds of millions of words of English than their younger counterparts.

As Prof. Harald Baayen, who heads the Alexander von Humboldt Quantitative Linguistics research group where the work was carried out puts it, “If you think linguistic skill involves something like being able to choose one word given another, younger adults seem to do better in this task. But, of course, proper understanding of language involves more than this. You have also to not put plausible but wrong pairs of words together. The fact that older adults find nonsense pairs – but not connected pairs – harder to learn than young adults simply demonstrates older adults’ much better understanding of language. They have to make more of an effort to learn unrelated word pairs because, unlike the youngsters, they know a lot about which words don’t belong together.”

The Tübingen research conclude that we need different tests for the cognitive abilities of older people – taking into account the nature and amount of information our brains process. “The brains of older people do not get weak,” says Michael Ramscar. “On the contrary, they simply know more.”