Posts tagged fMRI
Articles and news from the latest research reports.
Functional MRI provides support in operations on the brain
Researchers at the MedUni Vienna have proved in a so far unique multicenter study that clinical functional magnetic resonance tomography (fMRI), in the area in which the MedUni Vienna has a leading role internationally, is a safe method in brain surgery. With the aid of fMRI imaging can pinpoint to the millimetre where critical nerve fibres (e.g. vital for speech or hand function) lie and which have to be avoided – in operations on brain tumours for example.
"With the assistance of functional magnetic resonance tomography we are, if you like, drawing a red line for the surgeon so he knows where not to make an incision so as to avoid damage," says Roland Beisteiner from the University Department of Neurology at the MedUni Vienna. The neurologist and president of the Austrian Society for fMRI was playing a part in the development of fMRI as early as 1992, initiating its development in Austria. Since then this method has been developed and implemented at the University Department of Neurology and the High Field MRI Center of Excellence.
Now Beisteiner’s team have been able for the first time to demonstrate in a current paper in the top journal “Radiology" that functional magnetic resonance tomography provides diagnostic certainty in operations on the brain – no matter what the equipment is (whether a 7Tesla magnetic resonance tomograph as in Vienna or even only a 1.5Tesla), no matter in which location and also irrespective of who is operating it. The Medical Universities in Innsbruck and Salzburg, the Heinrich Heine University of Düsseldorf and the Stiftungsklinikum Koblenz (Koblenz Hospital Foundation) also took part in the study.
The “Imaging and Cognition Biology” Research Cluster of the MedUni and Vienna University
Likewise, with the help of functional magnetic resonance tomography, the teams of Beisteiner and Tecumseh Fitch (Faculty of Life Sciences of the University of Vienna) are investigating in a joint research cluster belonging to the MedUni Vienna and the University of Vienna whether the structural and syntactic processing of music takes place in similar areas of the brain as does the processing of speech. Says Beisteiner: “It is never exactly the same area of the brain; however, brain activities can overlap when talking or playing an instrument.”
The main focus of the research cluster is to determine precisely the common areas of the brain involved and to develop new treatments by activating them. These could perhaps then be used on people suffering from aphasia, which is a loss of language as the result of brain damage mostly to the left half of the brain.
According to Beisteiner there have been some astonishing results: “People, who could no longer speak because of their aphasia, have been able to sing the words they have learned to the matching tune.” From this one can conclude that it would seem to make sense to also practise music skills during speech therapy.
The “Imaging and Cognition Biology” research cluster is one of six joint clusters at the MedUni Vienna with the University of Vienna, which were set up in 2011. Further information: http://forschungscluster.meduniwien.ac.at/.
(Source: meduniwien.ac.at)
Similar connectivity profiles in humans and monkeys used to generate a Theory of Mind
The ability to infer emotion or intention in others from their outward appearance and behavior, has been called a “Theory of Mind” (TOM). While cognitive scientists have debated whether animals other than humans possess a TOM, many animals (like monkeys) clearly react to facial expression or body movements. One area of the human brain that has received considerable attention in discussions of TOM, is the temporo-parietal junction (TPJ). If each half of the brain is viewed as a boxing glove, the TPA corresponds to the junction between the “thumb” and body of the glove. To explore whether the TPJ regions of humans and monkeys have similar “functional connectivity” profiles, a group of Oxford researchers turned to high resolution at-rest fMRI. The researchers generated correlation maps between each time series obtained for specific voxel regions of interest. Their results, just published in PNAS, show that the most similar TPJ connectivity profiles correspond to areas that process, among other things, faces and social stimuli within the temporal cortex.
When the brain first begins to develop in the womb, the cortex is basically a smooth sheet. The most noticeable topological feature in the cortex of all higher vertebrates, the lateral or Sylvian fissure, begins to take shape as an invagination in the side that proceeds from front to back. This fold, with the TPA at its apex, remains as the primary feature of the cortex even as it grows increasingly convoluted. It is little wonder that many of the most interesting mental phenomena, and malady, are often attributed to this region. Stimulation of this area has produced effects as widespread as out of body experiences, impostor syndromes, and even phantom body doubles with precise geometrically offsets to the primary body position.
It is a bit of a paradox perhaps, that many studies which look for uniform or predictable features in the brain have instead hit upon the very region where any such pigeonholing is most labile. In other words, when the brain folds, the TPA is precisely the region where the most scrunching happens, with the result the mature structure typically shows the most variance. In animals like cats and many monkeys, the cortical gyri and sulci, have virtually the same pattern in each individual. In humans however, attempts to assign names to specific folds of the TPA region is like playing a game of pin the tail on the donkey. For example, the Angular gyrus, Wernicke’s area, Supramarginal gyrus, and Inferior parietal area, can all be variously designated as part of the TPA.
Recent attempts to define a default mode network (DMN) using fMRI have included this same region. In theory, the DMN can be used to distinguish sleep from arousal. It was noted that neurons which project out of the cortex in this region have, in effect, more options open to them than those virtually anywhere else in the brain. For example, directly under the angular gyrus is the area known as the temporo-parietal fiber association area. It includes at least seven long range white matter superhighways. That is not to say TPA neurons have free reign to board any tract they choose, (especially those like the optic radiations whose foundations are strongly and quickly set by myelin), but certainly the wide variance in behavioral correlates of these cells has an anatomical basis.
The Oxford study used Macaques, a monkey which has been on a separate evolutionary path from humans for around 30 million years. They note that the superior temporal (STS) region of the Macaque contains face cells that have been found to be more responsive to social cues rather than to identity. The researchers included the STS in their MRI meta-analysis, and also incorporated information from the BrainMap database, a large repository of neuroimaging data. While it is encouraging to see big data being put to use, it is often difficult to follow exactly how the data is processed to yield the so-called “activation likelihood estimation maps for activity elicited by theory of mind paradigms and by face discrimination or processing.”
As various federal projects begin to assemble connectomes for the human brain, functional connectivity studies that use highly processed MRI data, will need to be made as simple and straightforward as possible if they are to be put to widespread use. MRI tractography is a related technology that can assign physical connectivity by performing a meta-analysis on diffusion tensor data. Using scans and connectomes to generate theories to explain some of the strange mental phenomena generated secondary to stroke or by various kinds of electromagnetic stimulation are the best approaches we have at the moment. New technologies generated by the BRAIN Initiative will hopefully allow a finer-grained exploration of theory of mind.
Study charts exercise for stroke patients’ brains
A new study has found that stroke patients’ brains show strong cortical motor activity when observing others performing physical tasks — a finding that offers new insight into stroke rehabilitation.
Using functional magnetic resonance imaging (fMRI), a team of researchers from USC monitored the brains of 24 individuals — 12 who had suffered strokes and 12 age-matched people who had not — as they watched others performing actions made using the arm and hand that would be difficult for a person who can no longer use their arm due to stroke — actions such as lifting a pencil or flipping a card.
The researchers found that while the typical brain responded to the visual stimulus with activity in cortical motor regions that are generally activated when we watch others perform actions, in the stroke-affected brain, activity was strongest in these regions of the damaged hemisphere and strongest when stroke patients viewed actions they would have the most difficulty performing.
Activating regions near the damaged portion of the brain is like exercising it, building strength that can help it recover to a degree.
“Watching others perform physical tasks leads to activations in motor areas of the damaged hemisphere of the brain after stroke, which is exactly what we’re trying to do in therapy,” said Kathleen Garrison, lead author of a paper on the research. “If we can help drive plasticity in these brain regions, we may be able to help individuals with stroke recover more of the ability to move their arm and hand.”
Garrison, who completed the research while studying at USC and is currently a postdoctoral researcher at the Yale University School of Medicine, worked with Lisa Aziz-Zadeh of the USC Brain and Creativity Institute, based at the USC Dornsife College of Letters, Arts and Sciences, and the Division of Occupational Science and Occupational Therapy; Carolee Winstein, director of the Motor Behavior and Neurorehabilitation Laboratory in the Division of Biokinesiology and Physical Therapy; and former USC doctoral student Sook-Lei Liew and postdoctoral researcher Savio Wong.
Their research was posted online ahead of publication by the journal Stroke on June 6.
Using action-observation in stroke rehabilitation has shown promise in early studies, and this study is among the first to explain why it may be effective.
“It’s like you’re priming the pump,” Winstein said. “You’re getting these circuits engaged through the action-observation before they even attempt to move.”
The process is a kind of virtual exercise program for the brain that prepares you for the real exercise that includes the brain and body.
The study also offers support for expanding action-observation as a therapeutic technique, particularly for individuals who have been screened using fMRI and have shown a strong response to it.
“We could make videos of what patients will be doing in therapy and then have them watch it as homework,” Aziz-Zadeh said. “In some cases, it could pave the way for them to do better.”
Brain Imaging Study Eliminates Differences in Visual Function as a Cause of Dyslexia
A new brain imaging study of dyslexia shows that differences in the visual system do not cause the disorder, but instead are likely a consequence. The findings, published today in the journal Neuron, provide important insights into the cause of this common reading disorder and address a long-standing debate about the role of visual symptoms observed in developmental dyslexia.
Dyslexia is the most prevalent of all learning disabilities, affecting about 12 percent of the U.S. population. Beyond the primarily observed reading deficits, individuals with dyslexia often also exhibit subtle weaknesses in processing visual stimuli. Scientists have speculated whether these deficits represent the primary cause of dyslexia, with visual dysfunction directly impacting the ability to learn to read. The current study demonstrates that they do not.
“Our results do not discount the presence of this specific type of visual deficit,” says senior author Guinevere Eden, PhD, director for the Center for the Study of Learning at Georgetown University Medical Center (GUMC) and past-president of the International Dyslexia Association. “In fact our results confirm that differences do exist in the visual system of children with dyslexia, but these differences are the end-product of less reading, when compared with typical readers, and are not the cause of their struggles with reading.”
The current study follows a report published by Eden and colleagues in the journal Nature in 1996, the first study of dyslexia to employ functional Magnetic Resonance Imaging (fMRI). As in that study, the new study also shows less activity in a portion of the visual system that processes moving visual information in the dyslexics compared with typical readers of the same age.
This time, however, the research team also studied younger children without dyslexia, matched to the dyslexics on their reading level. “This group looked similar to the dyslexics in terms of brain activity, providing the first clue that the observed difference in the dyslexics relative to their peers may have more to do with reading ability than dyslexia per se,” Eden explains.
Next, the children with dyslexia received a reading intervention. Intensive tutoring of phonological and orthographic skills was provided, addressing the core deficit in dyslexia, which is widely believed to be a weakness in the phonological component of language. As expected, the children made significant gains in reading. In addition, activity in the visual system increased, suggesting it was mobilized by reading.
The researchers point out that these findings could have important implications for practice. “Early identification and treatment of dyslexia should not revolve around these deficits in visual processing,” says Olumide Olulade, PhD, the study’s lead author and post-doctoral fellow at GUMC. “While our study showed that there is a strong correlation between people’s reading ability and brain activity in the visual system, it does not mean that training the visual system will result in better reading. We think it is the other way around. Reading is a culturally imposed skill, and neuroscience research has shown that its acquisition results in a range of anatomical and functional changes in the brain.”
The researchers add that their research can be applied more broadly to other disorders. “Our study has important implications in understanding the etiology of dyslexia, but it also is relevant to other conditions where cause and consequence are difficult to pull apart because the brain changes in response to experience,” explains Eden.
(Source: explore.georgetown.edu)
Brain uses internal ‘average voice’ prototype to identify who is talking
The human brain is able to identify individuals’ voices by comparing them against an internal ‘average voice’ prototype, according to neuroscientists.
A study carried out by researchers at the University of Glasgow and reported in the journal Current Biology demonstrates that voice identity is coded in the brain by reference to two internal voice prototypes – one male, one female.
Voices that have the greatest difference from the prototype are perceived as more distinctive and produce greater neural activity than voices deemed very similar.
The researchers in the Institute of Neuroscience & Psychology conducted the study by generating a voice prototype through morphing 32 same-gender voices together resulting in a smooth, idealised voice with few irregularities.
They then generated different voices by altering the ‘distance-to-mean’ of the prototype voice – for example, changing the tone and pitch or morphing two or more voices together.
Using functional Magnetic Resonance Imaging (fMRI), the researchers were able to see increased neural activity the further from the prototype the voices were.
Professor Pascal Belin said: “Like faces, voices can be used to identify a person, yet the neural basis of this ability remains poorly understood. Here we provide the first evidence of a norm-based coding mechanism the brain uses to identify a speaker.
“The research indicates this is a similar process for the identification of faces, where the brain also uses an average face to compare against other faces it encounters in order to establish identity.
“So, rather than having to remember each single voice it hears every day for a lifetime, the brain facilitates the task of identification by remembering only the differences from the prototype it stores.
“It leads to a range of interesting and important questions, such as whether the prototypes are innate, stored templates or whether they are subject to environmental and cultural influences. Could the prototype consist of an average of all voices experiences during one’s life?”
(Image: Shutterstock)
Insomnia may cause dysfunction in emotional brain circuitry
A new study provides neurobiological evidence for dysfunction in the neural circuitry underlying emotion regulation in people with insomnia, which may have implications for the risk relationship between insomnia and depression.
“Insomnia has been consistently identified as a risk factor for depression,” said lead author Peter Franzen, PhD, an assistant professor of psychiatry at the University of Pittsburgh School of Medicine. “Alterations in the brain circuitry underlying emotion regulation may be involved in the pathway for depression, and these results suggest a mechanistic role for sleep disturbance in the development of psychiatric disorders.”
The study involved 14 individuals with chronic primary insomnia without other primary psychiatric disorders, as well as 30 good sleepers who served as a control group. Participants underwent an fMRI scan during an emotion regulation task in which they were shown negative or neutral pictures. They were asked to passively view the images or to decrease their emotional responses using cognitive reappraisal, a voluntary emotion regulation strategy in which you interpret the meaning depicted in the picture in order to feel less negative.
Results show that in the primary insomnia group, amygdala activity was significantly higher during reappraisal than during passive viewing. Located in the temporal lobe of the brain, the amygdala plays an important role in emotional processing and regulation.
In analysis between groups, amygdala activity during reappraisal trials was significantly greater in the primary insomnia group compared with good sleepers. The two groups did not significantly differ when passively viewing negative pictures.
“Previous studies have demonstrated that successful emotion regulation using reappraisal decreases amygdala response in healthy individuals, yet we were surprised that activity was even higher during reappraisal of, versus passive viewing of, pictures with negative emotional content in this sample of individuals with primary insomnia,” said Franzen.
The research abstract was published recently in an online supplement of the journal SLEEP, and Franzen will present the findings Wednesday, June 5, in Baltimore, Md., at SLEEP 2013, the 27th annual meeting of the Associated Professional Sleep Societies LLC.
The American Academy of Sleep Medicine reports that about 10 to 15 percent of adults have an insomnia disorder with distress or daytime impairment. According to the National Institute of Mental Health, 6.7 percent of the U.S. adult population suffers from major depressive disorder. Both insomnia and depression are more common in women than in men.
Study finds brain system for emotional self-control
Different brain areas are activated when we choose to suppress an emotion, compared to when we are instructed to inhibit an emotion, according a new study from the UCL Institute of Cognitive Neuroscience and Ghent University.
In this study, published in Brain Structure and Function, the researchers scanned the brains of healthy participants and found that key brain systems were activated when choosing for oneself to suppress an emotion. They had previously linked this brain area to deciding to inhibit movement.
"This result shows that emotional self-control involves a quite different brain system from simply being told how to respond emotionally," said lead author Dr Simone Kuhn (Ghent University).
In most previous studies, participants were instructed to feel or inhibit an emotional response. However, in everyday life we are rarely told to suppress our emotions, and usually have to decide ourselves whether to feel or control our emotions.
In this new study the researchers showed fifteen healthy women unpleasant or frightening pictures. The participants were given a choice to feel the emotion elicited by the image, or alternatively to inhibit the emotion, by distancing themselves through an act of self-control.
The researchers used functional magnetic resonance imaging (fMRI) to scan the brains of the participants. They compared this brain activity to another experiment where the participants were instructed to feel or inhibit their emotions, rather than choose for themselves.
Different parts of the brain were activated in the two situations. When participants decided for themselves to inhibit negative emotions, the scientists found activation in the dorso-medial prefrontal area of the brain. They had previously linked this brain area to deciding to inhibit movement.
In contrast, when participants were instructed by the experimenter to inhibit the emotion, a second, more lateral area was activated.
"We think controlling one’s emotions and controlling one’s behaviour involve overlapping mechanisms," said Dr Kuhn.
"We should distinguish between voluntary and instructed control of emotions, in the same way as we can distinguish between making up our own mind about what do, versus following instructions."
Regulating emotions is part of our daily life, and is important for our mental health. For example, many people have to conquer fear of speaking in public, while some professionals such as health-care workers and firemen have to maintain an emotional distance from unpleasant or distressing scenes that occur in their jobs.
Professor Patrick Haggard (UCL Institute of Cognitive Neuroscience) co-author of the paper said the brain mechanism identified in this study could be a potential target for therapies.
"The ability to manage one’s own emotions is affected in many mental health conditions, so identifying this mechanism opens interesting possibilities for future research.
"Most studies of emotion processing in the brain simply assume that people passively receive emotional stimuli, and automatically feel the corresponding emotion. In contrast, the area we have identified may contribute to some individuals’ ability to rise above particular emotional situations.
"This kind of self-control mechanism may have positive aspects, for example making people less vulnerable to excessive emotion. But altered function of this brain area could also potentially lead to difficulties in responding appropriately to emotional situations."
(Source: eurekalert.org)
Hit a 95 mph baseball? Scientists pinpoint how we see it coming
How does San Francisco Giants slugger Pablo Sandoval swat a 95 mph fastball, or tennis icon Venus Williams see the oncoming ball, let alone return her sister Serena’s 120 mph serves? For the first time, vision scientists at the University of California, Berkeley, have pinpointed how the brain tracks fast-moving objects.
The discovery advances our understanding of how humans predict the trajectory of moving objects when it can take one-tenth of a second for the brain to process what the eye sees.
That 100-millisecond holdup means that in real time, a tennis ball moving at 120 mph would have already advanced 15 feet before the brain registers the ball’s location. If our brains couldn’t make up for this visual processing delay, we’d be constantly hit by balls, cars and more.
Thankfully, the brain “pushes” forward moving objects so we perceive them as further along in their trajectory than the eye can see, researchers said.
“For the first time, we can see this sophisticated prediction mechanism at work in the human brain,” said Gerrit Maus, a postdoctoral fellow in psychology at UC Berkeley and lead author of the paper published today (May 8) in the journal, Neuron.
A clearer understanding of how the brain processes visual input – in this case life in motion – can eventually help in diagnosing and treating myriad disorders, including those that impair motion perception. People who cannot perceive motion cannot predict locations of objects and therefore cannot perform tasks as simple as pouring a cup of coffee or crossing a road, researchers said.
This study is also likely to have a major impact on other studies of the brain. Its findings come just as the Obama Administration initiates its push to create a Brain Activity Map Initiative, which will further pave the way for scientists to create a roadmap of human brain circuits, as was done for the Human Genome Project.
Using functional Magnetic Resonance Imaging (fMRI) Gerrit and fellow UC Berkeley researchers Jason Fischer and David Whitney located the part of the visual cortex that makes calculations to compensate for our sluggish visual processing abilities. They saw this prediction mechanism in action, and their findings suggest that the middle temporal region of the visual cortex known as V5 is computing where moving objects are most likely to end up.
For the experiment, six volunteers had their brains scanned, via fMRI, as they viewed the “flash-drag effect,”(a, b) a visual illusion in which we see brief flashes shifting in the direction of the motion.
“The brain interprets the flashes as part of the moving background, and therefore engages its prediction mechanism to compensate for processing delays,” Maus said.
The researchers found that the illusion – flashes perceived in their predicted locations against a moving background and flashes actually shown in their predicted location against a still background – created the same neural activity patterns in the V5 region of the brain. This established that V5 is where this prediction mechanism takes place, they said.
In a study published earlier this year, Maus and his fellow researchers pinpointed the V5 region of the brain as the most likely location of this motion prediction process by successfully using transcranial magnetic stimulation, a non-invasive brain stimulation technique, to interfere with neural activity in the V5 region of the brain, and disrupt this visual position-shifting mechanism.
“Now not only can we see the outcome of prediction in area V5,” Maus said. “But we can also show that it is causally involved in enabling us to see objects accurately in predicted positions.”
On a more evolutionary level, the latest findings reinforce that it is actually advantageous not to see everything exactly as it is. In fact, it’s necessary to our survival:
“The image that hits the eye and then is processed by the brain is not in sync with the real world, but the brain is clever enough to compensate for that,” Maus said. “What we perceive doesn’t necessarily have that much to do with the real world, but it is what we need to know to interact with the real world.”
(Source: newscenter.berkeley.edu)
Research determines how the brain computes tool use
With a goal of helping patients with spinal cord injuries, Jason Gallivan and a team of researchers at Queen’s University’s Department of Psychology and Centre for Neuroscience Studies are probing deep into the human brain to learn how it manages basic daily tasks.
The team’s most recent research, in collaboration with a group at Western University, investigated how the human brain supports tool use. The researchers were especially interested in determining the extent to which brain regions involved in planning actions with the hand alone would also be involved in planning actions with a tool. They found that although some brain regions were involved in planning actions with either the hand or tool alone, the vast majority were involved in planning both hand- and tool-related movements. In a subset of these latter brain areas the researchers further determined that the tool was in fact being represented as an extension of the hand.
“Tool use represents a defining characteristic of high-level cognition and behaviour across the animal kingdom but studying how the brain – and the human brain in particular – supports tool use remains a significant challenge for neuroscientists” says Dr. Gallivan. “This work is a considerable step forward in our understanding of how tool-related actions are planned in humans.”
Over the course of one year, human participants had their brain activity scanned using functional magnetic resonance imaging (fMRI) as they reached towards and grasped objects using either their hand or a set of plastic tongs. The tongs had been designed so they opened whenever participants closed their grip, requiring the participants to perform a different set of movements to use the tongs as opposed to when using their hand alone.
The team found that mere seconds before the action began, that the neural activity in some brain regions was predictive of the type of action to be performed upon the object, regardless of whether the hand or tool was to be used (and despite the different movements being required). By contrast, the predictive neural activity in other brain regions was shown to represent hand and tool actions separately. Specifically, some brain regions only coded actions with the hand whereas others only coded actions with the tool.
“Being able to decode desired tool use behaviours from brain signals takes us one step closer to using those signals to control those same types of actions with prosthetic limbs,” says Dr. Gallivan. “This work uncovers the brain organization underlying the planning of movements with the hand and hand-operated tools and this knowledge could help people suffering from spinal cord injuries.”
The research was recently published in eLife.
(Source: queensu.ca)
Food commercials excite teen brains
Watching TV commercials of people munching on hot, crispy French fries or sugar-laden cereal resonates more with teens than advertisements about cell phone plans or the latest car.
A new University of Michigan study found that regardless of body weight, teens had high brain activity during food commercials compared to nonfood commercials.
"It appears that food advertising is better at getting into the mind and memory of kids," said Ashley Gearhardt, U-M assistant professor of psychology and the study’s lead author. "This makes sense because our brains are hard-wired to get excited in response to delicious foods."
Children see thousands of commercials each year designed to increase their desire for foods high in sugar, fat and salt. Researchers from U-M, the Oregon Research Institute and Yale University analyzed how the advertising onslaught affects the brain.
Thirty teenagers (ages 14-17) ranging from normal weight to obese watched a television show with commercial breaks. Their brain activity was measured with a functional magnetic resonance imaging scanner.
The video showed 20 food commercials and 20 nonfood commercials featuring major brands such as McDonald’s, Cheerios, AT&T and Allstate Insurance. Study participants were asked to list five commercials they saw and to rate how much they liked the product or company featured in the ads.
Regions of the brain linked to attention, reward and taste were active for all participants, especially when food commercials aired. Overall, they recalled and liked food commercials better than nonfood commercials.
Teens whose weight was considered normal had greater reward-related brain activity when viewing the food commercials compared to obese adolescents. Gearhardt said this suggests that all teenagers, even those who are not currently overweight, are affected by food advertising and that exposure could lead to future weight gain in normal weight youth.
The study concluded that obese participants may attempt to control their response to food commercials, which might alter the way their brain responds. But if these teens are bombarded with frequent food cues, their self-control might falter—especially if they feel stressed, hungry or depressed.
Gearhardt said brain regions that are more responsive in lean adolescents during food commercials have been linked with future weight gain. These findings, which appear in the current issue of Social Cognitive and Affective Neuroscience, may inform the current debates about the impact of food advertising on minors.