Posts Tagged ‘ autism ’

Musical Learning

A new study throws some light on how musical aptitude can offset one very specific aspect of the aging process.

The question of Why Those Young Men Always Sound So Angry remains ripe for investigation.

In research comparing older patients with musical training to those without, older people who’d spent time regularly practicing or teaching music consistently displayed much faster neural reaction times to certain kinds of sounds.

The idea that the human brain has a deep relationship with music is obviously nothing new – but lately, research has been demonstrating more and more ways in which music is a major ingredient in mental health. For example, a 2007 study found that the brain reacts to music by automatically heightening attention, and one in 2010 found that an ear for harmony was correlated with a better ability to distinguish speech from noise.

The therapeutic implications of all this haven’t gone unnoticed. The neuroscientist Michael Merzenich has cured patients of chronic tinnitus (ear-ringing) by prescribing them musical training – and he’s had remarkable success using it to improve the responsiveness of autistic children.

Inspired by Merzenich’s work, a team led by Northwestern University’s Nina Kraus made up an experiment: They decided to record the reaction times of musicians‘ brains when they heard certain sounds, and compare those against the reaction times of people with no musical training.

As the journal Neurobiology of Aging reports, the team inserted electrodes directly into the patients’ brains during surgery, like this (WARNING – the following image is a very cool but very bloody photo of brain surgery): here, and recorded exactly how quickly their auditory cortex reacted to a variety of speech sounds.

They found that older musicians’ brains seemed to keep their youthful reaction speeds; at least when it came to a certain kind of sound: The syllable “da” – one of the “hard” vowel sounds known as formant transitions in science slang:

Although younger and older musicians exhibited equivalent response timing for the formant transition, older nonmusicians demonstrated significantly later re-sponse timing relative to younger nonmusicians … The main effect of musicianship observed for the neural response to the onset and the transition was driven solely by group differences in the older participants.

In other words, a musicians’ brain responds to the “da” sound just as quickly as it did in youth – but a nonmusician’s response time slows down significantly as it ages.

The slowdown isn’t much – only a few milliseconds – but in brain time, that can be enough to cause problems. See, we’re not talking about conscious reaction time here – this is electrophysiological reaction time – the speed at which information travels in the brain.

Why does this matter? Because mental issues like autism, senile dementia and schizophrenia are all related to very slight timing errors in the brain’s elaborate communication patterns. An aging brain isn’t so much an old clock as an old city. Ever notice how the most ancient cities tend to be the ones with the weirdest cultures? Well, there ya go.

Just like old cities, though, autism and dementia and schizophrenia – and aging – can be scary sometimes, but they’re also the sources of great breakthroughs, and remarkable insights, and all sorts of conversations that couldn’t have happened otherwise.

What I’m saying is, the only measurable difference between a disorder and a gift is that one is helpful and the other isn’t. And in most cases, that difference really comes down to timing.

Autism & Reputation

People with autism process the concept of their social reputation in a fundamentally different way from non-autistic people, a new study finds.

"No animal shelter donations for you, Cratchet!"

Suppose I give you $100, and tell you you can donate some or all of it to the no-kill animal shelter across the street – or you can just pocket the whole wad and walk away. My guess is that a) you’d donate at least some of the money whether or not you really care about adorable puppies – and that b) the amount you donate would be higher if I’m standing right there watching you.

That, of course, is because whether or not I tell you explicitly to donate some of the money, you probably have no desire to behave like Ebenezer Scrooge in front of me. In short, your brain is wired to warn you that a public act of pointless selfishness is, socially, a non-starter.

But people with autism process this dynamic in a completely different way.

As the journal Proceedings of the National Academy of Sciences reports, a team led by Caltech’s Keise Izuma presented autistic volunteers with similar situations, and compared their behavior against that of a control group of non-autistic people. They found that when social reputation came into play, people with autism just didn’t seem to find it significant:

When asked to make real charitable donations in the presence or absence of an observer, matched healthy controls donated significantly more in the observer’s presence than absence… By contrast, people with high-functioning autism were not influenced by the presence of an observer at all in this task.

In other words, volunteers with autism consistently donated the same amount of money whether they were being watched or not. It’s not that they’re more selfish than anyone else – it’s that a reputation for altruism simply doesn’t factor into their thought process as they make those particular choices.

This groundbreaking work represents the first hard scientific evidence of a specific, quantifiable difference between the cognitive processes of autistic individuals and those without autism.

The research team confirmed their results by comparing how autistic people vs. control subjects performed on a simple math exam when they were being watched, as opposed to when they weren’t:

Both groups performed significantly better on a continuous performance task in the presence of an observer, suggesting intact general social facilitation in autism.

Thus, the team’s conclusion is that people with autism seem to lack – at least somewhat – a cognitive process that would allow them to intuitively take others’ moral opinions into account. Since autism spectrum disorders (ASD) are widely regarded as more developmental than strictly physiological, this study’s results help support the idea that our instincts about others’ opinions are learned, rather than inborn.

To understand exactly why the brains of autistic people work in such an fascinatingly unusual way, we’re going to need to do some diffusion and/or functional MRI scans of their brains as they make these choices.

But as for the rest of us, our minds are calibrated to flood us with reward chemicals when we perform generous acts – and evidently, those rewards are greater when we perform those acts in the presence of people whose opinions we care about.

So this holiday season, why not start a new tradition: gather all your friends together and go volunteering, or babysitting, or donating – or, hell, go save a kitten from a burning building. Whatever floats your happy little boat.

Autistic Development

Certain regions of the brains of autistic children develop much more slowly than in non-autistic brains, a new study reports.

Comparison of a control-group brain with an autistic one...in "PredatorVision."

As most of our brains mature throughout our adolescent years, our white matter – the tissue that connects separate brain regions and allows them to communicate with one another – undergoes vast amounts of growth, as areas like the parietal, temporal, and occipital lobes learn to work together more closely. In the brains of autistic adolescents, though, this white matter grows much more slowly.

Meanwhile, their gray matter – the tissue composed mostly of neurons’ cell bodies, where most intensive processing takes place – shows overgrowth in regions like the putamen and anterior cingulate cortex (ACC), which are heavily involved in social interaction. This study is one of the first to isolate such specific developmental differences in the brains of people with autism.

The term “autism” covers a wide spectrum of disorders, whose exact links and causes remain poorly understood – though people with autism tend to be united by certain symptoms, such as repetitive behaviors and difficulty developing social instincts. Autism disorders affect approximately one percent of the total U.S. population, and many researchers say that number is on the rise. Even so, scientists are only beginning to discover the neurological roots of many autism-related problems.

As the journal Human Brain Mapping reports, a team led by UCLA’s Jennifer Levitt set out to examine those roots by studying the brains of adolescent autistic boys under a T1-weighted MRI scan – a type of scan that yields especially clear images of white matter – and comparing those scans against equivalent ones of non-autistic boys’ brains.

Then, by re-scanning all those brains three weeks later, the researchers were able to track some intriguing changes, and discover some important developmental differences between autistic and non-autistic brains:

The typically developing boys demonstrated strong whole brain white matter growth during this period, but the autistic boys showed abnormally slowed white matter development, especially in the parietal, temporal, and occipital lobes. We also visualized abnormal overgrowth in autism in gray matter structures such as the putamen and anterior cingulate cortex.

In short, most lobes in the autistic boys’ brains showed abnormally low connectivity with other regions – while more primitive regions involved in reward, planning, empathy and emotion show abnormal overgrowth. These seem to be promising links between the neuroanatomy of autistic brains and some of the developmental hurdles faced by autistic children:

Our findings reveal aberrant growth rates in brain regions implicated in social impairment, communication deficits and repetitive behaviors in autism, suggesting that growth rate abnormalities persist into adolescence.

Still, it’s hard to say what exactly that overgrowth means. It’s possible that the putamen and ACC are more intra-connected than inter-connected in autistic brains, or it could be that their workloads are heavier for some reason – or it could be that they’re just developing differently in some way we don’t yet understand.

It also leaves another open question: what causes these developmental differences in the first place? Researchers have blamed everything from air pollution to white noise to genetics – but at this point, anyone who says they’re sure of a single cause is lying.

Though studies like this one may help teachers and parents tailor therapies to the autistic mind, we’ve still got a long way to go (or one hell of a major breakthrough) before we understand what exactly autism is – if it’s even one “thing” at all.

But I doubt that’ll prevent certain rude people from using self-diagnosed Asperger’s as an excuse.

Autistic Genetics

Some forms of autism seem to be linked with variations in certain genes, a new study says.

One of these chromosomes is not like the others (maybe).

The deletion of a certain cluster of 27 genes on the mammalian chromosome 16 – specifically a region known as 16p11.2 – causes autism-like features to develop in mouse brains. These mice exhibited hyperactivity, repetitive behaviors, and difficulty adjusting to new environments, much like human children with autism. (As I mention a lot on this blog, mouse brains provide pretty reliable models of certain human brain functions, which is why neuroscientists experiment on them.)

The idea that chromosome 16 might be linked to autism dates back to 2007, when Michael Wigler at Cold Spring Harbor Laboratory (CSHL) discovered that many children with autism had a deletion of a certain set of 27 genes in region 16p11.2.

Tired of acronyms yet? I sure hope not, because here come some more.

As the journal Proceedings of the National Academy of Sciences (PNAS) reports, a team led by Guy Horev at CSHL genetically engineered mice to manifest this same chromosomal copy number variation (CNV):

We used chromosome engineering to generate mice harboring deletion of the chromosomal region corresponding to 16p11.2, as well as mice harboring the reciprocal duplication. These 16p11.2 CNV models have dosage-dependent changes in gene expression, viability, brain architecture, and behavior. For each phenotype, the consequence of the deletion is more severe than that of the duplication.

In short, a deletion of those 27 genes produced autism-like symptoms, while mice with an extra copy of region 16p11.2 didn’t seem to be autistic at all.

Interestingly, half the mice with the deletion died soon after birth. The ones that survived to adulthood were physically healthy and fertile, but when the researchers studied their brains under MRI scans, they found a set of neurological symptoms that were all too recognizable:

[The mice] have alterations in the hypothalamus and exhibit a “behavior trap” phenotype—a specific behavior characteristic of rodents with lateral hypothalamic and nigrostriatal lesions.

The hypothalamus is a brain region involved in regulating our hormones, balancing our body temperature, and motivating us to perform semi-automatic tasks like eating, drinking, and sleeping. The nigrostriatal pathway connects the midbrain’s substantia nigra to the forebrain’s striatum; it’s a major dopamine pathway that’s involved in motivating movement. Abnormalities in all these regions have been linked with autism in previous studies.

The next step in this research will be to pinpoint which of the 27 genes in region 16p11.2 impact autistic development in what ways. The researchers hope future discoveries along those lines will help doctors diagnose autism early in a child’s life, or perhaps even predict its likelihood based on the genetics of the parents.

Like other predictive genetic tests, this could lead to some tough ethical dilemmas for would-be mothers and fathers – but it’s also likely to lead to more proactive treatments. And besides, even if you know your child will be born with autism, you never know if he or she might be the next Daniel Tammett or Temple Grandin.

Autism From the Inside

Have you ever wondered how reality feels to a mathematical savant? One person in particular would like to help you with that.

Daniel Tammet: Math Superhero.

Daniel Tammet is an unusual guy for several reasons: he’s a “high-functioning” autistic savant who can recite pi to more than 22,000 digits, he’s got a talent for translating his subjective experiences into words, and he’s dedicated to explaining his synethesic perception of numbers to lucky listeners and readers.

In this fascinating TED talk, he shares some insight on how his mind works:

In my books, I explore the nature of perception and how different kinds of perceiving create different kinds of knowing and understanding. … I believe our personal perceptions, you see, are at the heart of how we acquire knowledge. Aesthetic judgments, rather than abstract reasoning, guide and shape the process by which we all come to know what we know.

Tammet goes on to describe how numbers are far more than just abstract concepts to him – they have colors and shapes, and even personalities. In fact, he explains, he’s able to perform complex calculations in his head because they don’t feel like calculations at all – instead, he intuitively fits numbers’ shapes and colors together in a beautiful harmony, which “translates” back into the problem’s solution.1

In a way, this invites comparisons with the method computers use to perform calculations: by taking advantage of the physical properties of electricity, circuit boards turn electronic switches on and off, and the resulting binary sequence (i.e., sequence of “on/off” switches) can be translated into a number. By shuffling huge amounts of these numbers around, computers can check the spellings of words, or render beautiful pictures.

But what’s mind-blowing about Tammet’s brain is that he’s doing this in reverse: he uses his aesthetic sensibility to perform numeric calculations, and sense whether the results are accurate.

Tammet's rendering of a pi-landscape.

There on the left is a painting Tammet made of the first few digits of pi. The colors and shapes, he says, represent various numbers, and the landscape reflects the way they fit together in his mind. But if I understand him correctly, the image isn’t metaphorical – it’s a literal depiction of the way numbers look and feel to him.

As Tammet points out in his talk, though, this ability isn’t limited to those with autism – to some extent, most of us have some related talents. One example is phonemes, the sounds that compose words: most people seem to have an intuitive sense for what feelings or ideas certain sounds should correspond to.

Take, for instance, words for “butterfly.” In the Amharic language of Ethiopia, it’s “birrobirro.” In Icelandic, it’s “fífrildi.” In the Native American Sioux language, it’s “kimimi.” The list goes on and on – in hundreds of completely unrelated languages from all over the world, people choose sound-sequences that call to mind the light flapping of tiny wings.

Thus, in some sense, we’re all synesthetes, able to correlate one kind of pattern (sounds we make) with a totally different kind (visuals we see) – and to somehow feel that this matchup is “right.”

How exactly these sorts of intuition work on the neurophysiological level is a question that’s still wide-open for investigation. One promising set of avenues for research are the unusual functional connectivity preferences in the brains of autistic people: local connectivity is much higher, and distant connectivity much lower, than in non-autistic brains. Intriguingly, these are similar to functional connectivity patterns that emerge in non-autistic people when they focus intently on a task, such as memorizing or recalling a string of numbers.

As brain imaging technologies become more precise and feedback-oriented, the relationship between autistic functional connectivity and synesthesia – as well as other attributes of savantism, such as extraordinary memory – promises to yield some incredible insights not only into autism, but into the ways all of our connectomes form complex heterogeneous associations.

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1. As a complete side-note, this range of colors and feelings is very similar to the way I’ve always experienced phonemes and letters. Maybe that’s why I enjoy writing, reading, and learning new languages so much.

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