Meet the World’s Most Advanced Brain Scanner The super-MRI used in the Human Connectome Project is the ultimate brain hacking machine. (via Meet the World’s Most Advanced Brain Scanner | DiscoverMagazine.com)

Are the orange circles in this picture (right) different sizes? Your answer can reveal the size of your brain.

Most people perceive the central circle to be smaller, an effect known as the Ebbinghaus illusion. Samuel Schwarzkopf and colleagues at University College London created a series of images in which the relative sizes of the two circles varied, and asked 30 volunteers to estimate which of the two was larger.

The team then scanned each volunteer’s brain using fMRI while they were shown a black dot in various points of their visual field. From the scans, they were able to assess the size of the visual cortex.

They found that people with a smaller visual cortex experienced the Ebbinghaus illusion more strongly.

Schwarzkopf suggests that this is because the circuits in the visual cortex responsible for the illusion are the same size in everyone, but cover a greater proportion of a smaller visual cortex, causing a stronger effect.

The team also found that people with a smaller visual cortex tended to have bigger brains overall, though it is not clear why.

Journal reference: Nature Neuroscience, DOI: 10.1038/nn.2706

Adventures in Neurohumanities

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At Stanford University in 2012, a young literature scholar named Natalie Phillips oversaw a big project: a new way of studying the nineteenth-century novelist Jane Austen. No surprise there—Austen, a superstar of English literature and the inspiration for an endless array of Hollywood and BBC productions based on her work, has been the subject of thousands of scholarly papers.

But the Stanford study was different. Phillips used a functional magnetic resonance imaging (fMRI) machine to track the blood flow of readers’ brains when they read Mansfield Park. The subjects—mostly graduate students—were asked to skim an excerpt and then read it closely. The results were part of a study on reading and distraction.

The “neuro novel” story was quickly picked up by the mainstream media, from NPR to The New York Times. But the Austen project wasn’t merely a clever one-off—the brainchild, so to speak, of one imaginatively interdisciplinary scholar. And it wasn’t just the result of ambitious academics crossing brain science with “the marriage plot” in unholy matrimony simply to grab headlines. The Stanford study reflects a real trend in the humanities. At Yale University, Lisa Zunshine, now a literature scholar at the University of Kentucky, was part of a research team that studied modernist authors using fMRI, also in order to better understand reading. Rather than a cramped office or library carrel, the researchers got to use the Haskins Laboratory in New Haven, with funding by the Teagle Foundation, to carry out their project, in which twelve participants were given texts with higher and lower levels of complexity and had their brains monitored. (via Adventures in Neurohumanities | The Nation)

Theodore Berger, a biomedical engineer and neuroscientist at the University of Southern California in Los Angeles, envisions a day in the not too distant future when a patient with severe memory loss can get help from an electronic implant. In people whose brains have suffered damage from Alzheimer’s, stroke, or injury, disrupted neuronal networks often prevent long-term memories from forming. For more than two decades, Berger has designed silicon chips to mimic the signal processing that those neurons do when they’re functioning properly—the work that allows us to recall experiences and knowledge for more than a minute. Ultimately, Berger wants to restore the ability to create long-term memories by implanting chips like these in the brain.

The idea is so audacious and so far outside the mainstream of neuroscience that many of his colleagues, says Berger, think of him as being just this side of crazy. “They told me I was nuts a long time ago,” he says with a laugh, sitting in a conference room that abuts one of his labs. But given the success of recent experiments carried out by his group and several close collaborators, Berger is shedding the loony label and increasingly taking on the role of a visionary pioneer.

Berger and his research partners have yet to conduct human tests of their neural prostheses, but their experiments show how a silicon chip externally connected to rat and monkey brains by electrodes can process information just like actual neurons. “We’re not putting individual memories back into the brain,” he says. “We’re putting in the capacity to generate memories.” In an impressive experiment published last fall, Berger and his coworkers demonstrated that they could also help monkeys retrieve long-term memories from a part of the brain that stores them. (via Brain Implants Could Help Alzheimer’s and Others with Severe Memory Damage | MIT Technology Review)

Neuroscience: Idle minds

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For volunteers, a brain-scanning experiment can be pretty demanding. Researchers generally ask participants to do something — solve mathematics problems, search a scene for faces or think about their favoured political leaders — while their brains are being imaged.

But over the past few years, some researchers have been adding a bit of down time to their study protocols. While subjects are still lying in the functional magnetic resonance imaging (fMRI) scanners, the researchers ask them to try to empty their minds. The aim is to find out what happens when the brain simply idles. And the answer is: quite a lot.

Some circuits must remain active; they control automatic functions such as breathing and heart rate. But much of the rest of the brain continues to chug away as the mind naturally wanders through grocery lists, rehashes conversations and just generally daydreams. This activity has been dubbed the resting state. And neuroscientists have seen evidence that the networks it engages look a lot like those that are active during tasks.

Resting-state activity is important, if the amount of energy devoted to it is any indication. Blood flow to the brain during rest is typically just 5–10% lower than during task-based experiments1. And studying the brain at rest should help to show how the active brain works. Research on resting-state networks is helping to map the brain’s intrinsic connections by showing, for example, which areas of the brain prefer to talk to which other areas, and how those patterns might differ in disease. (via Neuroscience: Idle minds : Nature News & Comment)

What is an itch? Scientists have speculated that it is a mild manifestation of pain or perhaps a malfunction of overly sensitive nerve endings stuck in a feedback loop. They have even wondered whether itching is mostly psychological (just think about bed bugs for a minute). Now a study rules out these possibilities by succeeding where past attempts have failed: a group of neuroscientists have finally isolated a unique type of nerve cell that makes us itch and only itch.

In previous research, neuroscientists Liang Han and Xinzhong Dong of Johns Hopkins University and their colleagues determined that some sensory neurons with nerve endings in the skin have a unique protein receptor on them called MrgprA3. They observed under a microscope that chemicals known to create itching caused these neurons to generate electrical signals but that painful stimuli such as hot water or capsaicin, the potent substance in hot peppers, did not. (via Scientists Identify Neurons That Register Itch: Scientific American)

Scientists say they have a new explanation for how the brain breaks experiences into “events,” or the related groups that help us mentally organize the day’s many situations.

They propose that the brain may actually work from subconscious mental categories it creates based on how it considers people, objects, and actions are related.

Specifically, these details are sorted by temporal relationship, which means that the brain recognizes that they tend to—or tend not to—pop up near one another at specific times.

Their explanation challenges the dominant concept known as prediction error that says our brain draws a line between the end of one event and the start of another when things take an unexpected turn.

Scientists say they have a new explanation for how the brain breaks experiences into “events,” or the related groups that help us mentally organize the day’s many situations.

They propose that the brain may actually work from subconscious mental categories it creates based on how it considers people, objects, and actions are related.

Specifically, these details are sorted by temporal relationship, which means that the brain recognizes that they tend to—or tend not to—pop up near one another at specific times.

Their explanation challenges the dominant concept known as prediction error that says our brain draws a line between the end of one event and the start of another when things take an unexpected turn

This new concept of “shared temporal context” works very much like the object categories our minds use to organize objects, explains Anna Schapiro, a doctoral student in Princeton’s psychology department and lead author of the study published in the journal Nature Neuroscience.

“We’re providing an account of how you come to treat a sequence of experiences as a coherent, meaningful event,” Schapiro says. “Events are like object categories. We associate robins and canaries because they share many attributes: They can fly, have feathers, and so on. These associations help us build a ‘bird’ category in our minds.

“Events are the same, except the attributes that help us form associations are temporal relationships.”