Posts Tagged ‘brain scans’
Researchers Use Brain Scans to Translate Thoughts Into Words
If a picture is worth 1,000 words, how many words make up a thought?
Researchers at Princeton University looked at fMRI scans to identify brain regions that were activated when participants thought about certain objects, like a carrot or a house. Then the team generated a list of topics that were also associated with those words. They looked at the same fMRI scans to determine the brain activity that was shared by the words within each topic, as a puts it. For instance, thoughts about the idea of “furniture” shared similar patterns with words like “table,” “desk” and “chair.”
Once they could tell the fMRI activity that would be sparked by a particular topic, the researchers were able to look at the brain activity alone and extrapolate what the person was thinking about. If a scientist studying brain scans spotted the neural patterns corresponding to “chair,” he could tell that the person was thinking about furniture.
“Whatever subject matter is on someone's mind — not just topics or concepts, but also emotions, plans or socially oriented thoughts — is ultimately reflected in the pattern of activity across all areas of his or her brain," said the team’s senior researcher, Matthew Botvinick, an associate professor in Princeton's Department of Psychology and in the Princeton Neuroscience Institute.
The researchers started out with brain scans from a 2008 word association study, in which participants were shown a picture and a word of five objects in 12 categories. The participants had been asked to visualize the object for three seconds, and the fMRI recorded their neural activity. Then the Princeton researchers came up with a list of their own topics with which to characterize this fMRI data. They used a computer program to condense 3,500 Wikipedia articles about objects — like an airplane, heroin, birds and manual transmission. The program came up with 40 topics to which these things could relate — i.e. aviation, drugs, animals or machinery. (Their full paper is for those interested in the specific methods.)
They arranged the fMRI scans by subject matter, and were ultimately able to tell the general topic on a person’s mind. It was harder to pick out an individual object, however, the Princeton news office explains. The eventual goal is to translate brain activity patterns into the correct words to fully describe thoughts, the researchers say.
This could have applications for helping people with disabilities, for whom brain scans might be able to elucidate their thinking more effectively than pictures. The research appears in the journal Frontiers in Human Neuroscience.
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Wearable PET Scanner For Rats Enables Real-Time Monitoring of Awake, Moving Animals’ Brains
PET scan for pets
The RatCAP, for Rat Conscious Animal PET, is worn over a rat’s head like a crown. A system of springs and motion stabilizers help the rat hold its head high and walk around.
Positron emission tomography scans enable scientists to study the molecular processes of brain activity, both in animals and in humans. To use the scanners, a patient has to lie down with his or her head in a machine. But good luck telling a lab rat to sit still.
Usually, animals are immobilized or given anesthesia, although those methods make it impossible to study the correlation between neurochemistry and the animals’ behavior, , a physicist at Brookhaven National Laboratory. Scientists wanted a scanner that could correlate PET data with behavioral data.
They developed a tiny scanner that weighs 250 grams, and attaches to a rat’s head with a bracket that is screwed onto the skull.
The researchers wanted to test whether the wearable PET scanner could be used to correlate dopamine levels with the rats’ movement. They found that the more active the rats were, the lower the level of dopamine — a counterintuitive result, because dopamine increases are associated with excitability and reward.
The image at right shows the levels of a tracer chemical that binds to dopamine receptors located in the striatum.
The tests show the RatCAP can correlate brain chemistry measurements with behavioral observations, the researchers say.
The study included PET comparisons between the RatCAP subjects and rats that had been placed under anesthesia. The study is published in Nature Methods.
New Imaging Method Opens a Long-Term Porthole Into the Deep Brain
Whole-brain scans like functional magnetic resonance imaging allow scientists to watch brain activity unfold, but they don’t provide the level of detail you might need to watch degenerative diseases or cancer at work. Traditional light microscopes can only go so far, however, penetrating about 1/32 of an inch of tissue before it’s too dark to see. Scientists have been able to peer deeper by using micro-optics, but this is also just a snapshot of one moment in time, and it’s almost impossible to return to the same spot twice. What’s more, the act of taking a peek — shoving a micro-optical device deep into the brain — can cause injury or infection.
Mark Schnitzer, a Stanford biology and applied physics professor, outlines a new option in this week’s issue of Nature Medicine. It starts with implanting tiny glass tubes, about half the width of a grain of rice, into the deep brain of a mouse. Once the tubes are in place, the brain is protected from the outside environment, and scientists can stick a tiny endoscope inside. The glass tube has a window on the end through which scientists can image neurons and monitor them over time.
“It's a bit like looking through a porthole in a submarine,” Schnitzer said in a Stanford news release.
The technique allows researchers to monitor individual cells as well as changes in individual animals, by comparing healthy tissue to diseased tissue. It could help researchers better understand aggressive brain cancers, for instance, which are known to be more deadly when they start in the deep brain as opposed to the surface. The method could be used for deep-tissue imaging studies in other parts of the body, too, Schnitzer said.
“We’re bringing the power of the microscope to tissues that lie beneath the penetration of light into the brain,” he said.
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According to New Study, fMRI Brain Scans May Predict Your Behavior Better Than You Can
In a study published last week, they showed neural signals can predict future behavior more accurately than people's own best guesses. This has for everything from advertisers, who would very much like to anticipate what you'll do, to educators, who could predict how much knowledge students will actually retain.
The researchers studied brain activity of people who watched public-service announcements about the importance of wearing sunscreen. They focused on two brain regions, the medial prefrontal cortex and the precuneus, which are both associated with self-awareness. The subjects -- mostly UCLA students -- were asked how they felt about sunscreen and how likely they were to use it. The researchers gave the subjects sunscreen to be sure they'd have access to it.
A week later, the participants reported how much sunscreen they actually used. About half had been able to accurately predict their behavior.
The neuroscientists developed a model that compared the subjects' brain activity to their own predictions, and found the model was accurate 75 percent of the time. In other words, it was more accurate than the students' own ability to predict how they would act. The findings were published last week in the .
Matthew Lieberman, a UCLA psychology and psychiatry professor who led the study, said people are not very good judges of what they will actually do.
"Many people 'decide' to do things but then don't do them," he says.
The study involved a small sample size -- just 20 students -- and more work needs to be done to understand the disconnect between your intentions and your actions. But the study could pave the way for neurologically informed marketing, education and even public health campaigns, UCLA says.
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Brooklyn Lawyer to Enter Brain Scan as Court Evidence for Client’s Veracity
The case could represent a legal precedent for sorting out truth from falsehood in a court of law
The lawyer, David Levin, represents a woman who claims that she no longer received good assignments from a temp agency after she complained of sexual harassment at a job site. A coworker at the temp agency claimed he heard a supervisor say the woman should not be placed on jobs because of the complaint.
That prompted Levin to have the coworker undergo a functional magnetic-resonance imaging (fMRI) brain scan by the company Cephos, which claims to provide scientific validation of whether someone is telling the truth. Now the proposed evidence will test the New York standards for scientific evidence in courts -- known as the Frye standard -- which typically requires the evidence to be considered reliable among the broader scientific community.
Both Cephos and another company called No Lie MRI have marketed their brain scans as lie detectors since 2007. They report accuracy rates from 75 percent to 98 percent under lab conditions, but many neuroscientists remain skeptical of, or outright opposed to, using brain scan technology in court.
We reported earlier on a Cephos-funded fMRI study at the University of Texas Southwestern Medical Center, which tested people who participated in a mock crime within the experiment. The test caught guilty parties, but also who were telling the truth.
Last year, an Illinois court allowed an expert to describe the fMRI brain scan of man accused of murdering a 10-year-old-girl. But that was presented as evidence of the man's mental illness during the sentencing phase of the trial, whereas the new Brooklyn case would be a legal first for determining truth-telling.
We'll be sure to keep an eye on whether this battleground between science and the law translates into wider use of brain scans or not. If it does pass muster with the Frye standard, expect even more debate over the use of in the future.
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Brain Scans Predict Who Benefits from Electrode Implants in Their Heads
fMRI helps scientists see interconnected brain networks and understand why happiness is a warm electrode
A new fMRI study showed that deep brain stimulation treatments seem to work by affecting a whole networked array of brain regions. Scientists focused on the subgenual region of the brain that tends to become hyperactive in people suffering from depression.
Patients whose condition improved because of the electrodes in their heads seemed to have a connection between the subgenual region and a part of their prefrontal cortex. By contrast, patients who did not benefit from DBS treatment had a connection between the subgenual region and the amygdale -- a part of the brain related to fear and other emotions.
The study, conducted at Emory University in Atlanta, may do more than just offer treatment to more people -- it has helped further our relatively paltry understanding of some of the brain's most complex internal processes.
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