Posts tagged neuroimaging
Articles and news from the latest research reports.
Study reveals information about the genetic architecture of brain’s grey matter
Findings may one day provide clues to understanding neuropsychiatric disorders
An international research team studying the structure and organization of the brain has found that different genetic factors may affect the thickness of different parts of the cortex of the brain.
The findings of this basic neuroscience study provide clues to better understanding the complex structure of the human brain. Ultimately, knowledge of genetic factors that underlie brain structure may help to identify individuals at risk for neuropsychiatric disorders, such as autism, schizophrenia or dementia. However, further research is necessary and the road to preventing or treating these conditions based on this work remains a long one.
The team was led by researchers at the University of California, San Diego, and included scientists from Virginia Commonwealth University, Boston University, Harvard Medical School and Massachusetts General Hospital, the University of Helsinki in Finland and the Veterans Affairs San Diego Healthcare System.
In the study, published online this week in the Proceedings of the National Academy of Sciences Online Early Edition, the team used MRI brain scan data collected from more than 200 pairs of twins between the ages of 55 and 65 and created a map based on genetic correlations between measures of thickness at different places on the cortex.
Using software developed by Michael Neale, Ph.D., professor of psychiatry and human genetics in the VCU School of Medicine, the team drew a genetic correlation map based on cortical thickness at thousands of points on the surface of the brain. These correlations were then analyzed to identify regions where the same genetic factors seem to have been operating. Twelve such regions in each hemisphere were identified, similar to an earlier study of measures of surface area.
“Our team has mapped genetic factors that influence the thickness of the cortex of the human brain,” said Neale who was a study contributor and co-author.
“Knowledge of the genetic organization of brain structures may guide the identification of risk factors for psychiatric disorders,” he said.
According to Neale, individuals differ in the thickness of these regions, and a twin study can help differentiate genetic from environmental factors that cause these differences at any one location. Twin studies also can estimate the degree to which the same versus different genetic factors affect two different characteristics.
Traditionally, maps of the human brain have been drawn using one of two types of information. The first is anatomical, such as the wrinkles on the surface, or cortex, of the brain. A second type of map, which may be called functional, is drawn from knowledge of how different parts of the brain are associated with particular functions. For example, Wernicke’s area on the left side of the brain is associated with the understanding of language.
The research builds on work published last year in Science by the same research team. That article reported on the initial development of the new software tool to study and explain how the brain works. It was considered the first map of the surface of the brain based on the basis of genetic information.
Next steps for this research will include correlating measures of these regions with outcomes, such as change in cognitive abilities since age 20, or lifetime cigarette smoking.
For nearly 30 years, Neale, an internationally known expert in statistical methodology, has developed and applied statistical models in genetic studies, primarily of twins and their relatives, with the goal of better understanding the brain and behavior.
Get the picture? New high-res images show brain activity like never before
In the middle of the human brain there is a tiny structure shaped like an elongated donut that plays a crucial role in managing how the body functions. Measuring just 10 millimeters in length and six millimeters in diameter, the hollow structure is involved in a complex array of behavioral, cognitive, and affective phenomena, such as the fight or flight response, pain regulation, and even sexual activity, according to Northeastern senior research scientist Ajay Satpute.
With a name longer than the structure itself, the “midbrain periaqueductal gray region,” or PAG, is extraordinarily difficult to investigate in humans because of its size and intricate structure, he said.
In research published online this week in the journal Proceedings of the National Academy of Science, Satpute and his colleagues at Northeastern’s Interdisciplinary Affective Science Laboratory explain how they hurdled these challenges by using state-of-the art imaging to capture this complex neural activity. The research could ultimately help scientists explore the grounds of human emotion like never before.
“The PAG’s functional properties occur at such small spatial scales that we need to capture its activity at very high resolution in order to understand it,” he explained.
Until recently, neuroimaging studies have been carried out on functional magnetic resonance imaging, or fMRI, instruments containing magnets of up to three Teslas, a measure of magnetic field strength. These instruments provide critical data for understanding how the brain’s different areas respond to different stimuli, but when those areas become sufficiently small and complicated, their resolution falls short.
In the case of the tiny PAG, this problem is paramount because the PAG wraps around a hollow core, or “aqueduct,” containing cerebrospinal fluid, Satpute said. Traditional fMRI instruments cannot distinguish neural activity occurring in the PAG from that occurring in the CS fluid. Even more difficult is identifying where within the PAG itself specific responses originate.
In collaboration with researchers at the Massachusetts General Hospital in Boston, Satpute and his colleagues used a high-tech fMRI instrument that contains a seven-Tesla magnet. The force of the instrument is so strong (albeit harmless) that one can feel its pull when simply walking by. Coupled with painstaking manual data analyses, Satpute was able to resolve activity in sub-regions of the PAG with more precision than ever before.
With their method in hand, the research team showed 11 human research subjects images of burn victims, gory injuries, and other content related to threat, harm, and loss while keeping tabs on the PAG’s activity. Researchers also showed the subjects neutral images such and then compared results between the two scenarios.
The proof-of-concept study showed emotion-related activity concentrated in particular areas of the PAG. While similar results have been demonstrated in animal models, nothing like it had previously been shown in human brains.
Using this methodology, the researchers said they would not only gain a better understanding of the PAG but also be able to investigate a range of brain-related research questions beyond this particular structure.
Seven-Tesla brain imaging provides an unprecedented view of regions like the PAG while they respond to stimuli, said Lisa Feldman Barrett, director of the Interdisciplinary Affective Science Laboratory. “Studies like this are a critical step forward in bridging human and nonhuman animal studies of emotion, because they offer a level of resolution in human brains that was previously possible only in studies of non-human animal,” she said.
Ballet dancers’ brains adapt to stop them feeling dizzy
Scientists have discovered differences in the brain structure of ballet dancers that may help them avoid feeling dizzy when they perform pirouettes.
The research suggests that years of training can enable dancers to suppress signals from the balance organs in the inner ear.
The findings, published in the journal Cerebral Cortex, could help to improve treatment for patients with chronic dizziness. Around one in four people experience this condition at some time in their lives.
Normally, the feeling of dizziness stems from the vestibular organs in the inner ear. These fluid-filled chambers sense rotation of the head through tiny hairs that sense the fluid moving. After turning around rapidly, the fluid continues to move, which can make you feel like you’re still spinning.
Ballet dancers can perform multiple pirouettes with little or no feeling of dizziness. The findings show that this feat isn’t just down to spotting, a technique dancers use that involves rapidly moving the head to fix their gaze on the same spot as much as possible.
Researchers at Imperial College London recruited 29 female ballet dancers and, as a comparison group, 20 female rowers whose age and fitness levels matched the dancers’.
The volunteers were spun around in a chair in a dark room. They were asked to turn a handle in time with how quickly they felt like they were still spinning after they had stopped. The researchers also measured eye reflexes triggered by input from the vestibular organs. Later, they examined the participants’ brain structure with MRI scans.
In dancers, both the eye reflexes and their perception of spinning lasted a shorter time than in the rowers.
Dr Barry Seemungal, from the Department of Medicine at Imperial, said: “Dizziness, which is the feeling that we are moving when in fact we are still, is a common problem. I see a lot of patients who have suffered from dizziness for a long time. Ballet dancers seem to be able to train themselves not to get dizzy, so we wondered whether we could use the same principles to help our patients.”
The brain scans revealed differences between the groups in two parts of the brain: an area in the cerebellum where sensory input from the vestibular organs is processed and in the cerebral cortex, which is responsible for the perception of dizziness.
The area in the cerebellum was smaller in dancers. Dr Seemungal thinks this is because dancers would be better off not using their vestibular systems, relying instead on highly co-ordinated pre-programmed movements.
“It’s not useful for a ballet dancer to feel dizzy or off balance. Their brains adapt over years of training to suppress that input. Consequently, the signal going to the brain areas responsible for perception of dizziness in the cerebral cortex is reduced, making dancers resistant to feeling dizzy.
“If we can target that same brain area or monitor it in patients with chronic dizziness, we can begin to understand how to treat them better.”
Another finding in the study may be important for how chronic dizzy patients are tested in the clinic. In the control group, the perception of spinning closely matched the eye reflexes triggered by vestibular signals, but in dancers, the two were uncoupled.
“This shows that the sensation of spinning is separate from the reflexes that make your eyes move back and forth,” Dr Seemungal said. “In many clinics, it’s common to only measure the reflexes, meaning that when these tests come back normal the patient is told that there is nothing wrong. But that’s only half the story. You need to look at tests that assess both reflex and sensation.”
Feelings forge stronger memories
Bad experiences enhance memory formation about places, scientists at The University of Queensland have found.
Dr Oliver Baumann from the Queensland Brain Institute found that associating negative imagery with specific locations activates a part of the brain responsible for forming memory of places during navigation – the parahippocampal cortex.
“This heightened recall occurs automatically, without people even being aware that the negative imagery is affecting their memories,” said Dr Baumann, who worked on the study in the QBI’s Mattingley lab.
“It could serve as a cue for avoiding potential threats,” Dr Baumann said.
“Our findings show that emotions can exert a powerful influence on spatial and navigational memory for places.
“In future we might be able to boost memory functions by triggering the positive side-effects of emotional arousal, while avoiding the need for negative experiences.”
For the research, Professor Jason Mattingley built a “virtual house” and staged events in each room unrelated to the subject navigating the house.
The events were designed to elicit an emotional response – positive, negative, or neutral, and varied in their rate of occurrence.
“The events were illustrated using images from the International Affective Picture System library and included dramatic scenes of attack and threat, as well as more pleasant imagery,” Dr Baumann said.
The day after navigating through the house, participants viewed static images of the house without the emotional imagery, while their neural activity was recorded using an MRI scanner.
“The results showed that emotional arousal exerted a powerful influence on memory by enhancing parahippocampal activity,” Dr Baumann said.
The study was published in the Journal of Cognitive Neuroscience.
(Source: uq.edu.au)
Getting an expected award music to the brain’s ears
Several studies have shown that expecting a reward or punishment can affect brain activity in areas responsible for processing different senses, including sight or touch. For example, research shows that these brain regions light up on brain scans when humans are expecting a treat. However, researchers know less about what happens when the reward is actually received—or an expected reward is denied. Insight on these scenarios can help researchers better understand how we learn in general.
To get a better grasp on how the brain behaves when people who are expecting a reward actually receive it, or conversely, are denied it, Tina Weis of Carl-von-Ossietzky University and her colleagues monitored the auditory cortex—the part of the brain that processes and interprets sounds—while volunteers solved a task in which they had a chance of winning 50 Euro cents with each round, signaled by a specific sound. Their findings show that the auditory cortex activity picked up both when participants were expecting a reward and received it, as well as when their expectation of receiving no reward was correct.
The article is entitled “Feedback that Confirms Reward Expectation Triggers Auditory Cortex Activity.” It appears in the Articles in Press section of the Journal of Neurophysiology, published by the American Physiological Society.
Methodology
The researchers worked with 105 healthy adult volunteers with normal hearing. While each volunteer received a functional MRI (fMRI)—a brain scan that measures brain activity during tasks—the researchers had them solve a task with sounds where they had the chance of winning money at the end of each round. At the beginning of a round participants heard a sound and had to learn if this sound signified that they could win a 50 Euro cents reward or not. They then saw a number on a screen and had to press a button to indicate whether the number was greater or smaller than 5. If the sound before indicated that they could receive a reward and they solved the number task quickly and correctly, an image of a 50 Euro cents coin appeared on the screen. The researchers monitored brain activity in the subjects’ auditory cortex throughout the task, paying special attention to what happened when they received the reward, or not, at the end of the round.
Results
The study authors found that when the volunteers were expecting and finally received a reward, then their auditory cortex was activated. Similarly, there was an increase in brain activity in this area when the subjects weren’t expecting a reward and didn’t get one. There was no additional activity when they were expecting a reward and didn’t get one.
Importance of the Findings
These findings add to accumulating evidence that the auditory cortex performs a role beyond just processing sound. Rather, this area of the brain appears to be activated during other activities that require learning and thought, such as confirming expectations of receiving a reward.
"Our findings thus support the view of a highly cognitive role of the auditory cortex," the study authors say.
(Source: eurekalert.org)
![Maths experts are “made, not born”
A new study of the brain of a maths supremo supports Darwin’s belief that intellectual excellence is largely due to “zeal and hard work” rather than inherent ability.
University of Sussex neuroscientists took fMRI scans of champion ‘mental calculator’ Yusnier Viera during arithmetical tasks that were either familiar or unfamiliar to him and found that his brain did not behave in an extraordinary or unusual way.
The paper, published this week (23 September 2013) in PLOS ONE, provides scientific evidence that some calculation abilities are a matter of practice. Co-author Dr Natasha Sigala says: “This is a message of hope for all of us. Experts are made, not born.”
Cuban-born Yusnier holds world records for being able to name the days of the week for any dates of the past 400 years, giving his answer in less than a second. This is the kind of ability sometimes found in those with autism, although Yusnier is not on the autistic spectrum. Unlike those with autism or the related condition Asperger’s, he is able to explain exactly how he calculates his answers – and even teaches his system and has written books on the subject.
The study, carried out at the Clinical Imaging Sciences Centre on the University of Sussex campus, suggests that Yusnier has honed his ability to create short cuts to his answers by storing information in the middle part of the brain specialised for long-term working memory (the hippocampus and surrounding cortex). This type of memory helps us carry out tasks in our area of expertise with speed and efficiency.
Although the left side of his brain was activated during mathematical problems – which is normal for all brains – the scientists observed that something slightly different happened when Yusnier was presented with unfamiliar problems.
The scans showed marked connectivity of the anterior parts of the brain (prefrontal cortex), which are involved in decision making, during the unfamiliar calculations. This supports Yusnier’s report that he was building in an extra step to his mental processes to turn an unfamiliar problem into a familiar one. His answers to the unfamiliar questions had an 80 per cent degree of accuracy (compared with more than 90 per cent for familiar questions) and his responses were slightly slower.
Dr Sigala explains: “Although this kind of ability is seen among some people with autism, it is much rarer in those not on that spectrum. Brain scans of those with autism tend to show a variety of activity patterns, and autistic people are not able to explain how they reach their answer.
“With Yusnier, however, it is clear that his expertise is a result of long-term practice – and motivation.”
She adds: “It was beyond the scope of our paper to discuss the debate on deliberate practice vs. innate ability. But our study does not provide evidence for specific innate ability for mental calculations. As put by Charles Darwin to Francis Galton: ‘ […] I have always maintained that, excepting fools, men did not differ much in intellect, only in zeal and hard work; I still think this an eminently important difference.’”](http://40.media.tumblr.com/749a98eac0fa21f91c01da24b2bf7089/tumblr_mtqmqtOttT1rog5d1o1_500.png)
Maths experts are “made, not born”
A new study of the brain of a maths supremo supports Darwin’s belief that intellectual excellence is largely due to “zeal and hard work” rather than inherent ability.
University of Sussex neuroscientists took fMRI scans of champion ‘mental calculator’ Yusnier Viera during arithmetical tasks that were either familiar or unfamiliar to him and found that his brain did not behave in an extraordinary or unusual way.
The paper, published this week (23 September 2013) in PLOS ONE, provides scientific evidence that some calculation abilities are a matter of practice. Co-author Dr Natasha Sigala says: “This is a message of hope for all of us. Experts are made, not born.”
Cuban-born Yusnier holds world records for being able to name the days of the week for any dates of the past 400 years, giving his answer in less than a second. This is the kind of ability sometimes found in those with autism, although Yusnier is not on the autistic spectrum. Unlike those with autism or the related condition Asperger’s, he is able to explain exactly how he calculates his answers – and even teaches his system and has written books on the subject.
The study, carried out at the Clinical Imaging Sciences Centre on the University of Sussex campus, suggests that Yusnier has honed his ability to create short cuts to his answers by storing information in the middle part of the brain specialised for long-term working memory (the hippocampus and surrounding cortex). This type of memory helps us carry out tasks in our area of expertise with speed and efficiency.
Although the left side of his brain was activated during mathematical problems – which is normal for all brains – the scientists observed that something slightly different happened when Yusnier was presented with unfamiliar problems.
The scans showed marked connectivity of the anterior parts of the brain (prefrontal cortex), which are involved in decision making, during the unfamiliar calculations. This supports Yusnier’s report that he was building in an extra step to his mental processes to turn an unfamiliar problem into a familiar one. His answers to the unfamiliar questions had an 80 per cent degree of accuracy (compared with more than 90 per cent for familiar questions) and his responses were slightly slower.
Dr Sigala explains: “Although this kind of ability is seen among some people with autism, it is much rarer in those not on that spectrum. Brain scans of those with autism tend to show a variety of activity patterns, and autistic people are not able to explain how they reach their answer.
“With Yusnier, however, it is clear that his expertise is a result of long-term practice – and motivation.”
She adds: “It was beyond the scope of our paper to discuss the debate on deliberate practice vs. innate ability. But our study does not provide evidence for specific innate ability for mental calculations. As put by Charles Darwin to Francis Galton: ‘ […] I have always maintained that, excepting fools, men did not differ much in intellect, only in zeal and hard work; I still think this an eminently important difference.’”
A shot of anxiety and the world stinks
In evolutionary terms, smell is among the oldest of the senses. In animals ranging from invertebrates to humans, olfaction exerts a primal influence as the brain continuously and subconsciously processes the steady stream of scent molecules that waft under our noses.
And while odors — whether the aroma of stinky socks or the sweet smell of baking bread — are known to stir the emotions, how they exert their influence biologically on the emotional centers of the human brain, evoking passion or disgust, has been a black box.
Now, however, researchers using powerful new brain imaging technologies are peeling back some of the mystery, revealing how anxiety or stress can rewire the brain, linking centers of emotion and olfactory processing, to make typically benign smells malodorous.
Writing today (Sept. 24, 2013) in the Journal of Neuroscience, a team led by Wen Li, a professor of psychology at the UW-Madison Waisman Center, reports that the brains of human subjects experience anxiety induced by disturbing pictures and text of things like car crashes and war transform neutral odors to distasteful ones, fueling a feedback loop that could heighten distress and lead to clinical issues like anxiety and depression.
The finding is important because it may help scientists understand the dynamic nature of smell perception and the biology of anxiety as the brain rewires itself under stressful circumstances and reinforces negative sensations and feelings.
"After anxiety induction, neutral smells become clearly negative," explains Li, who conducted the study with UW-Madison colleagues Elizabeth Krusemark and Lucas Novak, and Darren Gitelman of Northwestern University’s Feinberg School of Medicine. "People experiencing an increase in anxiety show a decrease in the perceived pleasantness of odors. It becomes more negative as anxiety increases."
Using behavioral techniques and functional magnetic resonance imaging (fMRI), Li’s group looked at the brains of a dozen human subjects with induced anxiety as they processed known neutral odors.
Functional MRI is a technology that enables clinicians and researchers to observe the working brain in action. Before entering the MRI where screens cycle through a series of disturbing pictures and text, subjects were exposed to and rated a panel of neutral smells.
In the course of the experiment, the Wisconsin team observed that two distinct and typically independent circuits of the brain — one dedicated to olfactory processing, the other to emotion — become intimately intertwined under conditions of anxiety. Subsequent to anxiety induction and the imaging process, subjects were asked again to rate the panel of neutral smells, most assigning negative responses to smells they previously rated as neutral.
"In typical odor processing, it is usually just the olfactory system that gets activated," says Li. "But when a person becomes anxious, the emotional system becomes part of the olfactory processing stream."
Although those two systems of the brain are right next to each other, under normal circumstances there is limited crosstalk between the two. However, under conditions of induced anxiety, the Wisconsin team observed the emergence of a unified network cutting across the two systems.
The results may have clinical implications in the sense that it begins to uncover the biological mechanisms at play during periods of anxiety. “We encounter anxiety and as a result we experience the world more negatively. The environment smells bad in the context of anxiety. It can become a vicious cycle, making one more susceptible to a clinical state of anxiety as the effects accumulate. It can potentially lead to a higher level of emotional disturbances with rising ambient sensory stress.”
Breakthrough Offers First Direct Measurement of Spinal Cord Myelin in Multiple Sclerosis
Real-time Imaging Technique Provides Essential Molecular Picture of Protective Nerve Sheath
Researchers have made an exciting breakthrough – developing a first-of-its-kind imaging tool to examine myelin damage in multiple sclerosis (MS). An extremely difficult disease to diagnose, the tool will help physicians diagnose patients earlier, monitor the disease’s progression, and evaluate therapy efficacy.
Case Western Reserve University School of Medicine scientists have developed a novel molecular probe detectable by positron emission tomography (PET) imaging. The new molecular marker, MeDAS, offers the first non-invasive visualization of myelin integrity of the entire spinal cord at the same time, as published today in an article in the Annals of Neurology.
“While MS originates in the immune system, the damage occurs to the myelin structure of the central nervous system. Our discovery brings new hope to clinicians who may be able to make an accurate diagnosis and prognosis in as little as a few hours compared to months or even years,” said Yanming Wang, PhD, senior author of study and associate professor of radiology at Case Western Reserve University School of Medicine. “Because of its shape and size, it is particularly difficult to directly detect myelin damage in the spinal cord; this is the first time we have been able to image its function at the molecular level.”
As the most common acquired autoimmune disease currently affecting more than two million people worldwide, MS is characterized by destruction of myelin, the membrane that protects nerves. Once damaged, it inhibits the nerves’ ability to transmit electrical impulses, causing cognitive impairment and mobility dysfunction. So far, there is no cure for MS, therapies are only available that modify the symptoms.
In addition to its role in monitoring the effects of myelin-repair drugs currently under development, the new imaging tool offers a real-time quantitative clinical diagnosis of MS. A long lag exists between the onset of disease, physical symptoms in the patient and diagnosis via behavioral testing and magnetic resonance imaging (MRI). The lesions, or plaques, as detected by a MRI in the brain and spinal cord are not myelin specific and thus poorly associated with a patient’s disease severity or progression. There is an urgent need to find a new imaging marker that correlates with a patient’s pathology.
“This discovery has open the door to develop new drugs that can truly restore nerve function, not just modify the symptoms,” said Robert Miller, PhD, co-author on the study, vice president for research for Case Western Reserve and the Allen C. Holmes Professor of Neurological Diseases at the School of Medicine. “A cure for MS requires both repairing myelin and a tool to measure the mechanism.”
For the past 20 years, Miller’s lab has been working tirelessly to create new myelin-repair therapies that would restore nerve function. Successful translation of new drugs from animal studies to human clinical trials is contingent upon researchers’ ability to measure and evaluate the effectiveness of a therapy.
Created by Wang’s laboratory, the MeDAS molecular probe works like a homing device. Injected into the body intravenously, it is programmed to seek out and bind only to myelin in the central nervous system, i.e., the brain, spinal cord and optic nerves. A positron-emitting radioisotope label on the molecule allows a PET scanner to detect the targets and quantify their intensity and location. The data can then be reconstructed into an image as shown in the article: http://onlinelibrary.wiley.com/doi/10.1002/ana.23965/abstract.
“This is an indispensable tool to help find a new way to treat MS down the road” said Chunying Wu, PhD, first author of the study and instructor of radiology at Case Western Reserve. “It can also be used as a platform technology to unlock the mysteries of other myelin related diseases such as spinal cord injury.”
(Source: casemed.case.edu)
First evidence that fear memories can be reduced during sleep
A fear memory was reduced in people by exposing them to the memory over and over again while they slept. It’s the first time that emotional memory has been manipulated in humans during sleep, report Northwestern Medicine® scientists.
The finding potentially offers a new way to enhance the typical daytime treatment of phobias through exposure therapy by adding a nighttime component. Exposure therapy is a common treatment for phobia and involves a gradual exposure to the feared object or situation until the fear is extinguished.
"It’s a novel finding," said Katherina Hauner, a postdoctoral fellow in neurology at Northwestern University Feinberg School of Medicine. "We showed a small but significant decrease in fear. If it can be extended to pre-existing fear, the bigger picture is that, perhaps, the treatment of phobias can be enhanced during sleep."
Hauner did the research in the lab of Jay Gottfried, associate professor of neurology at Feinberg and senior author of the paper.
The study will be published Sept. 22 in the journal Nature Neuroscience.
Previous projects have shown that spatial learning and motor sequence learning can be enhanced during sleep. It wasn’t previously known that emotions could be manipulated during sleep, Northwestern investigators said.
In the study, 15 healthy human subjects received mild electric shocks while seeing two different faces. They also smelled a specific odorant while viewing each face and being shocked, so the face and the odorant both were associated with fear. Subjects received different odorants to smell with each face such as woody, clove, new sneaker, lemon or mint.
Then, when a subject was asleep, one of the two odorants was re-presented, but in the absence of the associated faces and shocks. This occurred during slow wave sleep when memory consolidation is thought to occur. Sleep is very important for strengthening new memories, noted Hauner, also a research scientist at the Rehabilitation Institute of Chicago.
"While this particular odorant was being presented during sleep, it was reactivating the memory of that face over and over again which is similar to the process of fear extinction during exposure therapy," Hauner said.
When the subjects woke up, they were exposed to both faces. When they saw the face linked to the smell they had been exposed to during sleep, their fear reactions were lower than their fear reactions to the other face.
Fear was measured in two ways: through small amounts of sweat in the skin, similar to a lie detector test, and through neuroimaging with fMRI (functional magnetic resonance imaging). The fMRI results showed changes in regions associated with memory, such as the hippocampus, and changes in patterns of brain activity in regions associated with emotion, such as the amygdala. These brain changes reflected a decrease in reactivity that was specific to the targeted face image associated with the odorant presented during sleep.
Covert operations: Your brain digitally remastered for clarity of thought
Neurofeedback can enhance the signal-to-noise ratio in thought, enabling a sharper focus on tasks—and a better understanding of brain-computer interfaces.
The sweep of a needle across the grooves of a worn vinyl record carries distinct sounds: hisses, scratches, even the echo of skips. For many years, though, those yearning to hear Frank Sinatra sing “Fly Me to the Moon” have been able to listen to his light baritone with technical clarity, courtesy of the increased signal-to-noise ratio of digital remasterings.
Now, with advances in neurofeedback techniques, the signal-to-noise ratio of the brain activity underlying our thoughts can be remastered as well, according to the recent discovery of a research team led by Stephen LaConte, an assistant professor at the Virginia Tech Carilion Research Institute.
LaConte and his colleagues specialize in real-time functional magnetic resonance imaging, a relatively new technology that can convert thought into action by transferring noninvasive measurements of human brain activity into control signals that drive physical devices and computer displays in real time. Crucially, for the ultimate goal of treating disorders of the brain, this rudimentary form of mind reading enables neurofeedback.
“Our brains control overt actions that allow us to interact directly with our environments, whether by swinging an arm or singing an aria,” LaConte said. “Covert mental activities, on the other hand—such as visual imagery, inner language, or recollections of the past—can’t be observed by others and don’t necessarily translate into action in the outside world.”
But, LaConte added, brain–computer interfaces now enable us to eavesdrop on previously undetectable mental activities.
In the recent study, the scientists used whole-brain, classifier-based real-time functional magnetic resonance imaging to understand the neural underpinnings of brain–computer interface control. The research team asked two dozen subjects to control a visual interface by silently counting numbers at fast and slow rates. For half the tasks, the subjects were told to use their thoughts to control the movement of the needle on the device they were observing; for the other tasks, they simply watched the needle.
The scientists discovered a feedback effect that LaConte said he had long suspected existed but had found elusive: the subjects who were in control of the needle achieved a better whole-brain signal-to-noise ratio than those who simply watched the needle move. “When the subjects were performing the counting task without feedback, they did a pretty good job,” LaConte said. “But when they were doing it with feedback, we saw increases in the signal-to-noise ratio of the entire brain. This improved clarity could mean that the signal was sharpening, the noise was dropping, or both. I suspect the brain was becoming less noisy, allowing the subject to concentrate on the task at hand.”
The scientists also found that the act of controlling the computer–brain interface led to an increased classification accuracy, which corresponded with improvements in the whole-brain signal-to-noise ratio.
This enhanced signal-to-noise ratio, LaConte added, carries implications for brain rehabilitation. “When people undergoing real-time brain scans get feedback on their own brain activity patterns, they can devise ways to exert greater control of their mental processes,” LaConte said. “This, in turn, gives them the opportunity to aid in their own healing. Ultimately, we want to use this effect to find better ways to treat brain injuries and psychiatric and neurological disorders.”
“Dr. LaConte’s discovery represents a milestone in the development of noninvasive brain imaging approaches with potential for neurorehabilitation,” said Michael Friedlander, executive director of the Virginia Tech Carilion Research Institute and a neuroscientist who specializes in brain plasticity. “This research carries implications for people whose brains have been damaged, such as through traumatic injury or stroke, in ways that affect the motor system—how they walk, move an arm, or speak, for example. Dr. LaConte’s innovations with real-time functional brain imaging are helping to set the stage for the future, for capturing covert brain activity and creating better computer interfaces that can help people retrain their own brains.”