Posts Tagged ‘ fMRI ’

Forget Me Not

Having trouble remembering where you left your keys? You can improve with a little practice, says a new study.

"I've forgotten more than you'll ever...wait, what was I saying?"

It’s an idea that had never occurred to me before, but one that seems weirdly obvious once you think about it: people who train their brains to recall the locations of objects for a few minutes each day show greatly improved ability to remember where they’ve left things.

No matter what age you are, you’ve probably had your share of “Alzheimer’s moments,” when you’ve walked into a room only to forget why you’re there, or set something down and immediately forgotten where you put it. Attention is a limited resource, and when you’re multitasking, there’s not always enough of it to go around.

For people with real Alzheimer’s disease, though, these little moments of forgetfulness can add up to a frustrating inability to complete even simple tasks from start to finish. This is known as mild cognitive impairment (MCI), and its symptoms can range from amnesia to problems with counting and logical reasoning.

That’s because all these tasks depend on memory – even if it’s just the working memory that holds our sense of the present moment together – and most of our memories are dependent on a brain structure called the hippocampus, which is one of the major areas attacked by Alzheimer’s.

What exactly the hippocampus does is still a hotly debated question, but it seems to help sync up neural activity when new memories are “written down” in the brain, as well as when they’re recalled (a process that rewrites the memory anew each time). So it makes sense that the more we associate a particular memory with other memories – and with strong emotions - the more easily even a damaged hippocampus will be able to help retrieve it.

But now, a team led by Benjamin Hampstead at the Emory University School of Medicine has made a significant breakthrough in rehabilitating people with impaired memories, the journal Hippocampus reports: the researchers have demonstrated that Alzheimer’s patients suffering from MCI can learn to remember better with practice.

The team took a group of volunteers with MCI and taught them a three-step memory-training strategy: 1) the subjects focused their attention on a visual feature of the room that was near the object they wanted to remember, 2) they memorized a short explanation for why the object was there, and 3) they imagined a mental picture that contained all that information.

Not only did the patients’ memory measurably improve after a few training sessions – fMRI scans showed that the training physically changed their brains:

Before training, MCI patients showed reduced hippocampal activity during both encoding and retrieval, relative to HEC. Following training, the MCI MS group demonstrated increased activity during both encoding and retrieval. There were significant differences between the MCI MS and MCI XP groups during retrieval, especially within the right hippocampus.

In other words, the hippocampus in these patients became much more active during memory storage and retrieval than it had been before the training.

Now, it’s important to point out that that finding doesn’t necessarily imply improvement – studies have shown that decreased neural activity is often more strongly correlated with mastery of a task than increased activity is – but it does show that these people’s brains were learning to work differently as their memories improved.

So next time you experience a memory slipup, think of it as an opportunity to learn something new. You’d be surprised what you can train your brain to do with a bit of practice.

That is, as long as you remember to practice.

Learning Expectations

Researchers have isolated a specific pathway our brains use when learning new beliefs about others’ motivations, a new study says.

"M'lord! 'Tis improper to influence the lady's anterior cingulate!"

Though this type of learning, like many others, depends heavily on the neurotransmitter chemical dopamine‘s influence in a set of ancient brain structures called the basal ganglia, it’s also influenced by the rostral anterior cingulate cortex (ACC) – a structure that helps us weigh certain emotional reactions against others – indicating that emotions like empathy also play crucial roles.

As we play competitively against other people, our brains get to work constructing mental models that aim to predict our opponents’ future actions. This means we’re not only learning from the consequences of our own actions, but figuring out the reasons behind others‘ actions as well. This ability is known as theory of mind, and it’s thought to be one of the major mental skills that separates the minds of humans – and of our closest primate cousins – from those of other animals.

Though plenty of studies have examined the neural correlates of straightforward cause-and-effect learning, the process by which we learn from the actions of other people still remains somewhat unclear – largely because complex emotions like empathy and regret seem to involve many areas of the brain, including parts of the temporal, parietal and prefrontal cortices, as well as more ancient structures like the basal ganglia and cingulate cortex.

That’s why a team led by the University of Illinois’ Kyle Mathewson set out to track exactly what happens in our brains as we learn new ideas about other’s motivations, the journal Proceedings of the National Academy of Sciences reports.

The team used functional magnetic resonance imaging (fMRI) to study activity deep within volunteers’ brains as they played a competitive betting game against one another – focusing especially on moments when players learned whether they’d won or lost a round, and how much their opponents had wagered.

The researchers then used a computational model to match up patterns of brain activity with patterns of play – and found that the volunteers’ brains learned others’ behaviors and motivations through a complex interplay of several regions:

We found that the reinforcement learning (RL) prediction error was correlated with activity in the ventral striatum.

In other words, the ventral striatum – an area of the basal ganglia – was crucial for learning by reinforcement, much as the researchers expected…

In contrast, activity in the ventral striatum, as well as the rostral anterior cingulate (rACC), was correlated with a previously uncharacterized belief-based prediction error. Furthermore, activity in rACC reflected individual differences in degree of engagement in belief learning.

…while the anterior cingulate, on the other hand, seemed to dictate how attentively players watched their opponents’ patterns of play, and how much thought they put into predicting those patterns.

Thus, it appears that theory of mind is built atop an ancient “substructure” of simple reinforcement learning, which supports layers of more emotionally complex attitudes and beliefs about others’ thoughts, feelings and motivations – many of which are influenced by our perceptions of our own internal feelings.

And that points back to an important aspect of subjective experience in general: Many of our perceptions of the external world are extrapolated from our perceptions of our internal states. When we say, “It’s hot,” we really mean, “I feel hot;” when we say, “It’s loud in here,” we really mean, “It sounds loud to me.” In fact, the great philosopher Bertrand Russell has gone so far as to suggest that instead of saying, “I think,” it’d be more accurate to say “It thinks in me,” the same way we say “It’s raining.”

Anyway, no matter how you choose to phrase it, the point is that thinking isn’t a single process, but a relationship of many processes to one another. Which means that no matter how much we think we know, there’s always plenty left to learn.

Sacred Values

Principles on which we refuse to change our stance are processed via separate neural pathways from those we’re more flexible on, says a new study.

Some of our values can be more flexible than others...

Our minds process many decisions in moral “gray areas” by weighing the risks and rewards involved – so if the risk is lessened or the reward increased, we’re sometimes willing to change our stance. However, some of our moral stances are tied to much more primal feelings – “gut reactions” that remind us of our most iron-clad principles: don’t hurt innocent children, don’t steal from the elderly, and so on.

These fundamental values – what the study calls “sacred” values (whether they’re inspired by religious views or not) – are processed heavily by the left temporoparietal junction (TPJ), which is involved in imagining others’ minds; and by the left ventrolateral prefrontal cortex (vlPFC), which is important for remembering rules. When especially strong sacred values are called into question, the amygdala – an ancient brain region crucial for processing negative “gut” reactions like disgust and fear – also shows high levels of activation.

These results provide some intriguing new wrinkles to age-old debates about how the human mind processes the concepts of right and wrong. See, in many ancient religions (and some modern ones) rightness and wrongness are believed to be self-evident rules, or declarations passed down from on high. Even schools that emphasized independent rational thought – such as Pythagoreanism in Greece and Buddhism in Asia – still had a tendency to codify their moral doctrines into lists of rules and precepts.

But as scientists and philosophers like Jeremy Bentham and David Hume began to turn more analytical eyes on these concepts, it became clear that exceptions could be found for many “absolute” moral principles – and that our decisions about rightness and wrongness are often based on our personal emotions about specific situations.

The epic battle between moral absolutism and moral relativism is still in full swing today. The absolutist arguments essentially boil down to the claim that without some bedrock set of unshakable rules, it’s impossible to know for certain whether any of our actions are right or wrong. The relativists, on the other hand, claim that without some room for practical exceptions, no moral system is adaptable enough for the complex realities of this universe.

But now, as the journal Philosophical Transactions of the Royal Society B: Biological Sciences reports, a team led by Emory University’s Gregory Berns has analysed moral decision-making from a neuroscientific perspective – and found that our minds rely on rule-based ethics in some situations, and practical ethics in others.

The team used fMRI scans to study patterns of brain activity in 32 volunteers as the subjects responded “yes” or “no” to various statements, ranging from the mundane (e.g., “You are a tea drinker”) to the incendiary (e.g., “You are pro-life.”).

At the end of the questionnaire, the volunteers were offered the option of changing their stances for cash rewards. As you can imagine, many people had no problem changing their stance on, say, tea drinking for a cash reward. But when they were pressed to change their stances on hot-button issues, something very different happened in their brains:

We found that values that people refused to sell (sacred values) were associated with increased activity in the left temporoparietal junction and ventrolateral prefrontal cortex, regions previously associated with semantic rule retrieval.

In other words, people have learned to process certain moral decisions by bypassing their risk/reward pathways and directly retrieving stored “hard and fast” rules.

This suggests that sacred values affect behaviour through the retrieval and processing of deontic rules and not through a utilitarian evaluation of costs and benefits.

Of course, this makes it much easier to understand why “there’s no reasoning” with some people about certain issues – because it wasn’t reason that brought them to their stance in the first place. You might as well try to argue a person out of feeling hungry.

That doesn’t mean, though, that there’s no hope for intelligent discourse about “sacred” topics – what it does mean is that instead of trying to change people’s stances on them through logical argument, we need to work to understand why these values are sacred to them.

For example, the necessity of slavery was considered a sacred value all across the world for thousands of years – but today slavery is illegal (and considered morally heinous) in almost every country on earth. What changed? Quite a few things, actually – industrialization made hard manual labor less necessary for daily survival; overseas slaving expeditions became less profitable; the idea of racial equality became more popular…the list could go on and on, but it all boils down to a central concept: over time, the needs slavery had been meeting were addressed in modern, creative ways – until at last, most people felt better not owning slaves than owning them.

My point is, if we want to make moral progress, we’ve got to start by putting ourselves in the other side’s shoes – and perhaps taking a more thoughtful look at out own sacred values while we’re at it.

I Know Kung Fu

New technology may soon enable us download knowledge directly into our brains, says a new study.

"OK so there's people and planes and OH GOD what the hell am I learning??"

By decoding activation patterns from fMRI scans and then reproducing them as direct input to a precise area of the brain, the new system may be able to “teach” neural networks by example – priming them to fire in a certain way until they learn to do it on their own.

This has led everyone from io9 to the National Science Foundation to make Matrix references – and it’s hard to blame them. After all, immersive virtual reality isn’t too hard to imagine – but learning kung-fu via download, like grabbing an mp3? Sounds like pure sci-fi – especially since we know that the way muscle pathways form memories is pretty different from how we remember facts and images.

The basic idea is this: when you learn to perform a physical action – say, riding a bike or shooting a basketball – your muscles learn to coordinate through repetition. This is called procedural memory, because your muscles (and parts of your brain) are learning by repeating a procedure – in other words, a sequence of electrochemical actions – and (hopefully) improving the precision of that procedure with each run-through.

In contrast to this, we have declarative memories – memories of, say, the color of your favorite shirt, or where you had lunch today. Though declarative memories can certainly improve with practice – think of the last time you studied for an exam – there’s typically not an “awkward” stage as your brain struggles to learn how to recreate these memories. In short, once a bit of information is “downloaded” into your conscious awareness, it’s pretty much instantly available (until you forget it, of course).

Now, I could give some examples that blur the lines between these two types of memory – reciting a long list of words, for instance, seems to involve both procedural and declarative memory – but my point here is that procedural memories tend to require practice.

So it’s pretty surprising to read, in the journal Science, that a team led by Kazuhisa Shibata at Boston’s Visual Science Laboratory may have found a way to bridge the gap between these two types of memory.

The team began by taking fMRI scans of the visual cortex as volunteers looked at particular visual images – objects rotated at various angles. Once the team had isolated a precise activation pattern corresponding to a particular angle of orientation, they turned around and directly induced that same activation pattern in the volunteers’ brains:

We induced activity patterns only in early visual cortex corresponding to an orientation without stimulus presentation or participants’ awareness of what was to be learned. The induced activation caused VPL specific to the orientation.

In other words, the researchers triggered brain activity patterns corresponding to specific angles of visual orientation without telling the volunteers what the stimulus was going to be.

Then, when the scientists asked the volunteers what they’d “learned,” the  volunteers had no idea. But when the researchers asked them to pick a “best guess” orientation that seemed “right” to them, a significant percentage chose the orientation their brains had been trained to remember.

This isn’t exactly downloadable kung-fu – but it provides some of the first conclusive evidence that not only do repeated visual stimuli help sculpt brain networks – direct stimulation can sculpt the way those networks learn about visual stimuli.

Could we use technology like this to teach people to feel less anxious or depressed? Or to understand concepts they have trouble grasping? And what might happen if we could harness this technology to our own mental output? What if we could literally dream our way to new skills, or more helpful beliefs?

We’re not quite there yet, but it may very well happen in our lifetime.

The Brain Lab Tour

This past weekend, I got to visit one of the coolest places I’ve ever seen: the UCLA Laboratory of Neuro Imaging (LONI). So just for today, I’m gonna take a break from news reporting, and tell you a little about what goes on inside an actual cutting-edge neuroscience lab. Sound good? OK, let’s go!

I'd be okay with just bringing a tent and camping out here.

I’m not sure quite what I was expecting to see as I stepped through the lab’s electronically locked door – certainly not the roomful of clean, open-walled work areas that greeted me. I might’ve been standing in a sleek law office, or an advertising agency – except that the flatscreens adorning the walls displayed colorful 3-D brain maps and reams of dense scientific data.

Imagine being five years old, celebrating Christmas morning at Disneyland - you get the idea.

But before I could start running around making googly-eyes at everything, it was time to meet my host – the delightful Eileen Luders, who’d offered to give me a tour of the lab when I’d gushed about my enthusiasm for her work. Eileen studies neural correlates of meditative states, and she’s also interested in isolating tiny structural variations that correspond to specific kinds of intelligence. More on this awesomeness shortly.

After introductions and a bit of happy chitchat, Eileen led me to a small screening room, whose entire front wall was an enormous wraparound high-resolution video screen. From the control booth, a lab technician dimmed the lights and played us a promo video that was ten minutes of pure heaven. We flew through huge, detailed 3-D brain atlases, watching neural pathways assemble and disassemble before our eyes. We plunged into the brains of schizophrenics and drug abusers and meditators, as data from fMRI and DTI and OTI exploded into multicolored digital sculptures of these brains’ structures and functions.

When it was over (all too soon), I asked Eileen what the lab normally uses this room for. “Mostly meetings,” she said with a chuckle.

As we strolled back to her office, she explained the principle on which this lab works: all the scans are processed by one huge supercomputer array housed in a well-locked room. All a team (or scientist) needs to perform a basic scan is the lab’s permission, about $600, and the time and technical know-how to program the scan they want and parse its results into meaningful data.

Researchers do most of this coding and data analysis from the comfort of the cubicle-esque work areas that fill most of the lab – and this non-centralization frees up more time on the scanners for other researchers, which keeps the lab more affordable and efficient for everyone.

And then we got to talking about some really cool stuff.

I asked Eileen what had gotten her so interested in the neuroscience of meditative states, and she told me she’s always been fascinated by the chasm between subjective experience (i.e., learning how to meditate) and objective science (i.e., what happens in our brains when we meditate). So, she’s been working to help narrow that gap – to study the brain activity of meditators as they meditate, give them feedback about the results – and essentially do her best to act as a fairly seamless translator between mind and machine (and vice versa).

I asked her what it was like having monks visit the lab. She told me two things: “They’re incredibly sharp; incredibly present,” she said. “And they were really excited to see if the bathroom was as cool as everything else.” In short, monks frickin’ rule.

Thinking about meditation, I wondered aloud whether singing and chanting might reflect an inherently different cognitive process from speech. There’s some (very preliminary) research suggesting that certain tones and vocalizations (such as chanting “aum” or humming a major scale) may help modulate patterns of neural activity far more directly than words can. Eileen mentioned that she’s done a bit of research on yogic chanting that might point in this direction. (Too bad we can’t time-travel back to 1968 and put these guys in one of her scanners.)

Anyway, it’s easy to see why Eileen’s also interested in finding neural correlates for specific kinds of intelligence. This got us talking about one of her other pet projects: looking for neural correlates of gender differences. She pointed out that women’s brains are, on average, a little smaller than men’s – “But when you adjust a male and female brain to equal size,” she said, “the differences aren’t nearly as obvious as they might appear at first glance.”  (A few days later, she sent me a published, peer-reviewed paper she’s written on this topic; I’m looking forward to diving into it.)

By this time, it was starting to get late, so Eileen offered me a quick tour of the lab before rushing off to do more Awesome Neuroscience Stuff. We peeked through the window of the supercomputer room, where multicolored lights flickered on rows of imposing black towers. We poked our heads into the wet lab, where neuroanatomists actually freeze and dissect brains. We stopped by a few workstations where technicians were busy designing scanning programs or analyzing their output. I wish I’d been able to take photos.

And then it was time to say goodbye. As Eileen and I shook hands at the doorway, I couldn’t help feeling that I wanted to give her a hug – to hug the whole lab, and everyone in it. It just made me so happy to think that there are other people like us – people filled with a deep yearning to understand what’s going on inside our heads, and just how it works – people driven to dedicate massive amounts of time and money to finding the pieces of this crazy puzzle, and starting to fit a few of those pieces together.

But most of all, I’m so glad that those people are kind, and friendly, and every bit as geeky as I am. Neuroscience FTW!

Psychopathic Anatomy

The brains of psychopaths have a significant physical difference from those of non-psychopaths, says a new study.

Inside the mind of a psychopath. (I was expecting it to be...scarier...somehow.)

In a psychopath’s brain, white matter (connective neural tissue) links between the ventromedial prefrontal cortex (vmPFC) and amygdala are unusually weak. This means a major brain area involved in anticipating risk (the vmPFC) is only weakly connected with an area crucial for processing fear and sadness.

Though the word “psychopath” gets thrown around a lot, it doesn’t necessarily refer to a maniacal killer. It’s simply a term used to characterize personality disorders in which a person has difficulty linking their actions with feelings like empathy, regret, and guilt.

Because many psychopathic individuals learn to mask their difficulty experiencing these linkages, they often don’t get the therapies they need – so many do, in fact, end up committing crimes; or at least making life tough for their friends and family. Even as we get better at understanding the symptoms of psychopathy, though, the causes have remained somewhat poorly understood.

But now, as the Journal of Neuroscience reports, a team of researchers from several institutions have joined forces to study the neuroanatomy of psychopathic prisoners in detail.

The University of Wisconsin’s Joseph Newman has spent years studying and working with psychopathic prisoners in the Wisconsin state correctional system. Newman teamed up with Kent Kiehl, a psychologist from the University of New Mexico, who brought a mobile fMRI scanner to a Wisconsin prison and took detailed scans of 20 psychopathic prisoners’ brains. The team also took diffusion MRI scans, which are useful for precisely mapping tiny anatomical structures deep within the brain.

When the team compared this data against equivalent scans of 20 non-psychopathic prisoners’ brains, they found that psychopathic prisoners’ brains showed some significant structural abnormalities:

Using diffusion tensor imaging, we show that psychopathy is associated with reduced structural integrity in the right uncinate fasciculus, the primary white matter connection between vmPFC and anterior temporal lobe.

In short, the white matter connecting the vmPFC to the amygdala isn’t particularly sturdy in psychopaths’ brains. This abnormality is also related to some major functional differences:

Using functional magnetic resonance imaging, we show that psychopathy is associated with reduced functional connectivity between vmPFC and amygdala as well as between vmPFC and medial parietal cortex.

In other words (as you might expect) the lack of healthy white matter connectivity means the vmPFC doesn’t communicate with the amygdala very well in psychopaths’ brains.

This study provides some of the first clear data on just what it is, in specific anatomical and physiological terms, that makes the brain of a psychopath different from yours or mine.

While these discoveries don’t let these prisoners off the hook for the crimes they committed, the data does provide encouragement that more targeted therapies could help prepare psychopathic individuals to lead healthy lives in the outside world. It also reminds us that “the criminal mind” may be as much a medical concern as it is a moral one.

And that, I think, is good news both for psychopathic individuals and for the rest of us.

Musical Matchups

Our brains process music via different sensory pathways depending on what we think its source is, a new study finds.

Let me stop ya right there - "Stairway to Heaven" is off-limits.

As our brains organize information from our senses into a coherent representation of the world around us, they’re constantly hard at work associating data from one sense – say, sight – with data from another – say, hearing.

A lot of the time, this process is pretty straightforward – for instance, if we see a man talking and hear a nearby male voice, it’s typically safe for our brains to assume the voice “goes with” the man’s lip movements. But it’s also not too hard for others to trick this association process – as anyone who’s watched a good ventriloquism act knows.

Now, as the journal Proceedings of the National Academy of Sciences (PNAS) reports, a team led by HweeLing Lee and Uta Noppeney at the Max Planck Institute for Biological Cybernetics has discovered a way in which musicians‘ brains are specially tuned to correlate information from different senses when their favorite instruments are involved.

Neuroscientists have known for years that the motor cortex in the brains of well-trained guitar and piano players devotes much more processing power to fingertip touch and finger movement than the same area of a non-musician’s brain does. But what this new study tells us is that the brains of pianists are also much more finely-tuned to detect whether a finger stroke is precisely synchronous with a sound produced by the touch of a piano key.

To figure this out, the team assembled 18 pianists – amateurs who practice on a regular basis – and compared their ability to tell synchronous piano tones and keystrokes from slightly asynchronous ones while they lay in an fMRI scanner (presumably by showing them this video). The researchers also tested the pianists’ ability to tell when lip movements were precisely synchronized with spoken sentences.

The team then compared the musicians’ test results against the results of equivalent tests taken by 19 non-musicians. What they found was pretty striking:

Behaviorally, musicians exhibited a narrower temporal integration window than non-musicians for music but not for speech. At the neural level, musicians showed increased audiovisual asynchrony responses and effective connectivity selectively for music in a superior temporal sulcus-premotor-cerebellar circuitry.

In short, pianists are much more sensitive to a slight asynchrony between a keystroke and a piano tone than non-musicians are – but this sensitivity doesn’t also apply to speech and lip movements. In other words, pianists’ brains are unusually sensitive to asynchrony only when it involves piano keystrokes.

Another important finding is that the researchers could predict how sensitive the musicians would be to asynchrony based on asynchronies the fMRI scanner detected in their motor cortex:

Our results suggest that piano practicing fine tunes an internal forward model mapping from action plans of piano playing onto visible finger movements and sounds.

This means there’s a direct link between inter-neural coordination and ear-eye coordination. I don’t know about you, but I think that’s pretty incredible.

The researchers hope that as they study similar data from musicians who work with other instruments, they’ll come to better understand how our brains learn to associate stimuli from one sense from information from another – and maybe even how they learn when and when not to “sync up” these stimuli in our subjective experience of reality.

It’s too bad we can’t hook up the brain of, say, Mozart or Hendrix to an fMRI scanner – who knows what amazing discoveries we might make. But even so, I’m sure you can think of some living musical geniuses whose brains you’d like to see in action.

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