Posts Tagged ‘ imaging ’

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.

Podcast 1: Our Interview With Joshua Vogelstein

Here it is – the first Connectome podcast!


Click here to subscribe in iTunes.

Join us as we talk with Joshua Vogelstein, a leading connectomics researcher, about the Open Connectome Project, an international venture to make data on neural connectivity available to everyone, all over the world. It’s like Google Maps for your brain.

Here’s a direct link to download the mp3.

We’ve learned a lot while working on this first episode, and future ones will be much cleaner and higher-fi.

Anyway, enjoy!

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.

Clarke’s Third Law

Today I want to take a break from breaking news and tell you about the new love of my life: my Emotiv EPOC neuroheadset.

Love at first sight.

This thing costs $299, and it is worth every penny. It uses 14 sensors positioned around my scalp to create a wireless EEG interface between my brain and my computer. I can move objects onscreen by thinking about it. I can click the mouse by thinking “click.” I can watch real-time video maps of my brain activity as I think about different ideas. I can summon specific feelings to navigate through photo albums sorted by emotion.

In short, the future is here, and it is awesome.

Brain-machine interfaces aren’t exactly earth-shaking news anymore, I know. I’ve written here about thought-controlled cursors, and here about sensory feedback systems that allow monkeys to control virtual hands and literally feel virtual textures. But this device makes this technology available and (relatively) affordable for me – and for you.

And we can do anything we want with it.

Are ya with me here?

Anything.

For instance, I spent most of last night watching waves of neural communication coruscate across my brain as I meditated, imagined, planned, observed, understood, realized, believed and calculated. I watched my left and right hemispheres signal to one another, like two great whales exchanging songs across an ocean, as they worked together to complete tasks. I watched tsunamis of synchronized activation blaze across the screen as disparate thoughts coalesced into dawning realizations. I watched congeries of light dance in the darkness as I thought, “I believe” or “I trust” or “I love.”

And that was just our first night together.

This is what I was talking about when I said we need devices that create real-time feedback loops between our brains and our computers, so we can watch the patterns our thoughts generate as we’re thinking them - the most intimate link ever between human consciousness and technology. We’re hurtling toward the culmination of a process that began millions of years ago in Africa; when one ape, a little smarter than his cousins, looked down at a rock and thought, “I want to use that for something.”

So, guess what this device is being used for right now. Well, for one thing, it’s providing easy computer access to people with physical disabilities, which is fantastic – but other than that, it’s mainly being marketed as a new gimmick for controlling video games.

Come on, people – we can dream so much bigger than this.

By way of inspiration, here’s my all-time favorite short sci-fi story, Exhalation by Ted Chiang. It’ll tell you everything you want to know about my aspirations.

And here’s a little song to set the mood.

Welcome to the Age of Technosophy. Let’s see where our imaginations take us.

Neuron Holograms

A new technique will allow us to watch hundreds of neurons in 3D, in real time, at a resolution that’s 50 times greater than before.

"Hey, what the... you're not a neuron!"

The technology, known as digital holographic microscopy (DHM), was imported into neuroscience from materials science. It measures differences in the wavelengths of harmless lasers as they travel through a certain region of the brain – and this allows a computer system to construct precise 3D models of neurons at work.

Since individual neurons are transparent, scientists used to use various kinds of chemical stains in order to study them.  The cells have to be extracted and placed in a Petri dish before being stained, which causes all kinds of hangups: it takes time, it changes the chemical composition of the cells, and (obviously) it physically damages them.

Patch clamps and other electrodes allow scientists to study the electrochemical activity of neurons without removing them, but even these techniques tend to be damaging – and they’re really only helpful for studying small groups of neurons.

But DHM blasts all these problems away – with lasers.

DHM [images cells] with a laser beam, by pointing a single wavelength at an object, collecting the distorted wave on the other side, and comparing it to a reference beam. A computer then numerically reconstructs a 3D image of the object — in this case, neurons — using an algorithm developed by the authors. In addition, the laser beam travels through the transparent cells and important information about their internal composition is obtained.

And all this happens without chemically disrupting the cells, physically damaging them, or even moving them at all. Even cooler, it can record high-resolution images of hundreds of neurons at a time – giving us a much clearer picture of the brain’s patterns of chemical and electrical activity, and the relationships between the two.

In fact, the Journal of Neuroscience reports, a team led by Pierre Magistretti of Switzerland’s Brain Mind Institute showed off DHM’s awesomeness by using it to track some neurotransmitter chemicals in real-time 3D:

In a recent study, we showed that the quantitative monitoring of the phase signal by DHM was a simple label-free method to study the effects of glutamate on neuronal optical responses … DHM is the first imaging technique able to monitor dynamically and in situ the activity of these cotransporters [a certain kind of neurotransmitters] during physiological and/or pathological neuronal conditions.

A genuine Real Genius moment for neuroscience.

The team hope this new technology will lead to quicker and more accurate diagnoses of neurodegenerative diseases like Alzheimer’s and Parkinson’s – and even to the development of more precisely targeted drugs to combat the exact kinds of damage those diseases cause:

What normally would take 12 hours in the lab can now be done in 15 to 30 minutes, greatly decreasing the time it takes for researchers to know if a drug is effective or not.

It’s also exciting to think about the potential of integrating DHM data with information gathered in fMRI scans – it could give us a much more detailed understanding of how larger activation patterns in the brain are created by the interactions between individual neurons. In short, this could be a major boost for connectomics research.

Sometimes, you’ve got to take a step back and think, “You know, we’re actually using lasers and holograms for real scientific purposes.” Living in the future’s pretty cool, isn’t it?

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