Posts tagged brain activity
Articles and news from the latest research reports.
Speech processing while unconscious: Sleep inhibits action but not preparation and meaning
In a team effort between the Medical Research Council Cognition and Brain Sciences Unit (Cambridge, UK) and the Laboratory of Cognitive and Psycholinguistics Sciences, Ecole Normale Superiore (Paris), part of what we are capable of while sleeping has been unravelled.
People were asked to classify words belonging to one of two categories – animals or objects – by pressing buttons with the left or the right hand, and continued to do so until they have fallen asleep. Their brain activity indicated that they were able to decode the meaning of the words and intended to act but the unconscious state during sleep prevented them from responding (no movement of the fingers).
This result indicates that once a rule (animals press left/objects press right) is established during wakefulness it can still be implemented even during sleep. This means that the decoding networks in the brain process the spoken words and that information (if it is an animal or an object for instance) is passed to a motor plan signaling the intention and subsequent action. During sleep that action is inhibited (we do not purposefully move during sleep) but this study has found that the meaning extraction and subsequent action preparation remained but was slower and lasted longer.
To confirm this result a second study tested whether people could classify word or nonwords (like boat or foat). A similar pattern emerged, showing appropriate brain preparation activity for left or right button presses even if responses were inhibited by the sleep mechanisms.
New Study Examines Impact of Violent Media on the Brain
With the longstanding debate over whether violent movies cause real world violence as a backstop, a study published today in PLOS One found that each person’s reaction to violent images depends on that individual’s brain circuitry, and on how aggressive they were to begin with.
The study, which was led by researchers at the Icahn School of Medicine at Mount Sinai and the NIH Intramural Program, featured brain scans which revealed that both watching and not watching violent images caused different brain activity in people with different aggression levels. The findings may have implications for intervention programs that seek to reduce aggressive behavior starting in childhood.
“Our aim was to investigate what is going on in the brains of people when they watch violent movies,” said lead investigator Nelly Alia-Klein, PhD, Associate Professor of Neuroscience and Psychiatry at the Friedman Brain Institute and Icahn School of Medicine at Mount Sinai. “We hypothesized that if people have aggressive traits to begin with, they will process violent media in a very different way as compared to non-aggressive people, a theory supported by these findings.”
After answering a questionnaire, a group of 54 men were split by the research team into two groups—one with individuals possessing aggressive traits, including a history of physical assault, and a second group without these tendencies. The participants’ brains were then scanned as they watched a succession of violent scenes (shootings and street fights) on day one, emotional, but non-violent scenes (people interacting during a natural disaster) on day two, and nothing on day three.
The scans measured the subjects’ brain metabolic activity, a marker of brain function. Participants also had their blood pressure taken every 5 minutes, and were asked how they were feeling at 15 minute intervals.
Investigators discovered that during mind wandering, when no movies were presented, the participants with aggressive traits had unusually high brain activity in a network of regions that are known to be active when not doing anything in particular. This suggests that participants with aggressive traits have a different brain function map than non-aggressive participants, researchers said.
Interestingly, while watching scenes from violent movies, the aggressive group had less brain activity than the non-aggressive group in the orbitofrontal cortex, a brain region associated by past studies with emotion-related decision making and self-control. The aggressive subjects described feeling more inspired and determined and less upset or nervous than non-aggressive participants when watching violent (day 1) versus just emotional (day 2) media. In line with these responses, while watching the violent media, aggressive participants’ blood pressure went down progressively with time while the non-aggressive participants experienced a rise in blood pressure.
“How an individual responds to their environment depends on the brain of the beholder,” said Dr. Alia-Klein. “Aggression is a trait that develops together with the nervous system over time starting from childhood; patterns of behavior become solidified and the nervous system prepares to continue the behavior patterns into adulthood when they become increasingly coached in personality. This could be at the root of the differences in people who are aggressive and not aggressive, and how media motivates them to do certain things. Hopefully these results will give educators an opportunity to identify children with aggressive traits and teach them to be more aware of how aggressive material activates them specifically.”
Study provides more evidence that sleep apnea is hurting your brain
Employing a measure rarely used in sleep apnea studies, researchers at the UCLA School of Nursing have uncovered evidence of what may be damaging the brain in people with the sleep disorder — weaker brain blood flow.
(Image caption: This brain scan shows that the brain blood flow in a subject with obstructive sleep apnea (left) is markedly lower compared to a subject without the sleep disorder. Credit: UCLA)
In the study, published Aug. 28 in the peer-reviewed journal PLOS ONE, researchers measured blood flow in the brain using a non-invasive MRI procedure: the global blood volume and oxygen dependent (BOLD) signal. This method is usually used to observe brain activity. Because previous research showed that poor regulation of blood in the brain might be a problem for people with sleep apnea, the researchers used the whole-brain BOLD signal to look at blood flow in individuals with and without obstructive sleep apnea (OSA).
“We know there is injury to the brain from sleep apnea, and we also know that the heart has problems pumping blood to the body, and potentially also to the brain,” said Paul Macey, associate dean for Information Technology and Innovations at the UCLA School of Nursing and lead researcher for the study. “By using this method, we were able to show changes in the amount of oxygenated blood across the whole brain, which could be one cause of the damage we see in people with sleep apnea.”
Obstructive sleep apnea is a serious disorder that occurs when a person’s breathing is repeatedly interrupted during sleep, hundreds of times a night. Each time breathing stops, the oxygen level in the blood drops, which damages many cells in the body. If left untreated, it can lead to high blood pressure, stroke, heart failure, diabetes, depression and other serious health problems. Approximately 10 percent of adults struggle with obstructive sleep apnea, which is accompanied by symptoms of brain dysfunction, including extreme daytime sleepiness, depression and anxiety, and memory problems.
In this study, men and women — both with and without obstructive sleep apnea had their BOLD signals measured during three physical tasks while they were awake:
- The Valsalva maneuver: participants forcefully breathe out through a very small tube, which raises the pressure in the chest.
- A hand-grip challenge: participants squeeze hard with their hand.
- A cold pressor challenge: A participants’s right foot is put in icy water for a minute.
“When we looked at the results, we didn’t see much difference between the participants with and without OSA in the Valsalva maneuver,” said Macey. “But for the hand-grip and cold-pressor challenges, people with OSA saw a much weaker brain blood flow response.”
The researchers believe that the reason there were differences in the sleep apnea patients during the hand-grip and cold pressor challenge was because the signals from the nerves in the arms and legs had to be processed through the high brain areas controlling sensation and muscle movement, which was slower due to the brain injury. On the other hand, the changes from the Valsalva are mainly driven by blood pressure signaling in the chest, and do not need the sensory or muscle-controlling parts of the brain.
“This study brings us closer to understanding what causes the problems in the brain of people with sleep apnea,” concluded Macey.
The study also found the problem is greater in women with sleep apnea, which may explain the worse apnea-related outcomes in females than males. Studies recently published by the UCLA School of Nursing have shown that brain injury from sleep apnea is much worse in women than men.
The researchers are now looking at whether treatment for obstructive sleep apnea can reverse the damaging effects.
(Source: newsroom.ucla.edu)
Brain mechanism underlying the recognition of hand gestures develops even when blind
Does a distinctive mechanism work in the brain of congenitally blind individuals when understanding and learning others’ gestures? Or does the same mechanism as with sighted individuals work? Japanese researchers figured out that activated brain regions of congenitally blind individuals and activated brain regions of sighted individuals share common regions when recognizing human hand gestures. They indicated that a region of the neural network that recognizes others’ hand gestures is formed in the same way even without visual information. The findings are discussed in The Journal of Neuroscience.
Our brain mechanism perceives human bodies from inanimate objects and shows a particular response. A part of a region of the “visual cortex” that processes visual information supports this mechanism. Since visual information is largely used in perception, this is reasonable, however, for perception using haptic information and also for the recognition of one’s own gestures, it has been recently learned that the same brain region is activated. It came to be considered that there is a mechanism that is formed regardless of the sensory modalities and recognizes human bodies.
Blind and sighted individuals participated in the study of the research group of Assistant Professor Ryo Kitada of the National Institute for Physiological Sciences, National Institutes of Natural Sciences. With their eyes closed, they were instructed to touch plastic casts of hands, teapots, and toy cars and identify the shape. As it turned out, sighted individuals and blind individuals could make an identification with the same accuracy. Through measuring the activated brain region using functional magnetic resonance imaging (fMRI), for plastic casts of hands and not for teapots or toy cars, the research group was able to pinpoint a common activated brain region regardless of visual experience. On another front, it also revealed a region showing signs of activity that is dependent on the duration of the visual experience and it was also learned that this region functions as a supplement when recognizing hand gestures.
As Assistant Professor Ryo Kitada notes, “Many individuals are active in many parts of the society even with the loss of their sight as a child. Developmental psychology has been advancing its doctrine based on sighted individuals. I wish this finding will help us grasp how blind individuals understand and learn about others and be seen as an important step in supporting the development of social skills for blind individuals.”
Visualising plastic changes to the brain
Painless therapy
Transcranial magnetic stimulation (TMS) is a painless, non-invasive stimulation method, where an electromagnetic coil held above the head is used to generate a strong magnetic field. This method is deployed to activate or inhibit specific brain regions. Even though the number of its medical applications is constantly on the increase, TMS’ precise neuronal mechanisms of action are not, as yet, very well understood. That is because imaging used for humans, such as fMRI (functional magnetic resonance imaging), do not possess the temporal resolution necessary for recording neural activities in milliseconds. More rapid measurement methods, such as EEG or MEG, on the other hand, are affected by the induced magnetic field, with the results that strong interferences are generated that cover important information regarding immediate TMS-based changes to brain activities.
Observing effect on neurons in real time
High-res images of TMS effects have now for the first time been successfully generated by RUB researchers in animal testing. The work group headed by PD Dr Dirk Jancke, Institut für Neuroinformatik, utilises voltage-sensitive dyes which, anchored in cell membranes, send out fluorescent light signals once neurons get activated or inhibited. By using light, the researchers avoided the problem of measurement of artefacts occurring due to magnetic fields. “We can now demonstrate in real time how one single TMS pulse suppresses brain activity across a considerable region, most likely through mass activation of inhibiting brain cells,” says Dr Jancke. With higher TMS frequencies, each additional TMS pulse generates an incremental increase in brain activity. “This results in a higher cortical activation state, which opens up a time window for plastic changes,” explains Dr Vladislav Kozyrev, the first author of the study.
Chances for patients
The increased neuronal excitability may be utilised to effect specific reorganisation of cell connections by means of targeted learning processes. For example, through visual training after TMS, the ability to identify image contours improves; moreover, a combination of these methods enhances contrast perception in patients with amblyopia - a disorder of sight acquired during child development. For many neurological diseases of the brain, such as epilepsy, depression and stroke, specific models have been developed. “Deployed in animal testing, our technology has delivered high spatiotemporal resolution imaging data of cortical activity changes,” says Dirk Jancke. “We are hoping that these data will enable us to optimise TMS parameters and learning processes in a targeted manner, which are going to be used in future to adapt this technology for medical treatment of humans.”
Nature or nurture? It’s all about the message
Were Albert Einstein and Leonardo da Vinci born brilliant or did they acquire their intelligence through effort?
No one knows for sure, but telling people the latter – that hard work trumps genes – causes instant changes in the brain and may make them more willing to strive for success, indicates a new study from Michigan State University.
The findings suggest the human brain is more receptive to the message that intelligence comes from the environment, regardless of whether it’s true. And this simple message, said lead investigator Hans Schroder, may ultimately prompt us to work harder.
“Giving people messages that encourage learning and motivation may promote more efficient performance,” said Schroder, a doctoral student in clinical psychology whose work is funded by the National Science Foundation. “In contrast, telling people that intelligence is genetically fixed may inadvertently hamper learning.”
In past research by Stanford University psychologist Carol Dweck, elementary students performing a task were either praised for their intelligence (“You’re so smart!”) or for their effort (“You worked really hard!”) after correct responses. As the task became harder, children in the first group performed worse after their mistakes compared to the group that had heard effort was important.
The MSU study, which appears online in the journal Biological Psychology, offers what could be the first physiological evidence to support those findings, in the form of a positive brain response. “These subtle messages seem to have a big impact, and now we can see they have an immediate impact on how the brain handles information about performance,” Schroder said.
For the study, two groups of participants read different articles. One article reported that intelligence is largely genetic, while the other said the brilliance of da Vinci and Einstein was “probably due to a challenging environment. Their genius had little to do with genetic structure.”
Participants were instructed to remember the main points of the article and completed a simple computer task while their brain activity was recorded. The findings, in a nutshell:
- The group that read intelligence was primarily genetic paid more attention to their responses, as if they were more concerned with their performance. This extra attention, however, did not relate to performance on trials after errors, suggesting a disconnect between brain and behavior.
- In contrast, those who had read that intelligence was due to a challenging environment showed a more efficient brain response after they made a mistake, possibly because they believed they could do better on the next trial. The more attention these participants paid to mistakes, the faster their responses were on the next trial.
The study does not weigh in on the age-old “nature vs. nurture” debate, Schroder noted. Rather, it investigates the messages about the nature of abilities people are exposed to on a regular basis, from a teacher comforting a student (“It’s OK, not everyone can be a math person.”) to the sports announcer commenting on a player’s skill (“Wow, what a natural!”). These messages are thought to contribute to the attitudes or “mindsets” people hold about their intelligence and abilities.
The research started as part of Schroder’s honors thesis as an undergraduate at MSU working in the Clinical Psychophysiology Lab directed by Jason Moser, MSU assistant professor. Moser co-authored the study along with Tim Moran, an MSU graduate student in cognitive psychology, and Brent Donnellan, a former MSU professor who now works at Texas A&M University.
As an undergraduate and graduate student, Schroder has already co-written nine papers that have appeared in academic journals, including five as lead author. His work is supported by a three-year grant from the NSF’s Graduate Research Fellowship Program.
Dyslexic Readers Have Disrupted Network Connections in the Brain
Dyslexia, the most commonly diagnosed learning disability in the United States, is a neurological reading disability that occurs when the regions of the brain that process written language don’t function normally.
The use of non-invasive functional neuroimaging tools has helped characterize how brain activity is disrupted in dyslexia. However, most prior work has focused on only a small number of brain regions, leaving a gap in our understanding of how multiple brain regions communicate with one another through networks, called functional connectivity, in persons with dyslexia.
This led neuroscience PhD student Emily Finn and her colleagues at the Yale University School of Medicine to conduct a whole-brain functional connectivity analysis of dyslexia using functional magnetic resonance imaging (fMRI). They report their findings in the current issue of Biological Psychiatry.
"In this study, we compared fMRI scans from a large number of both children and young adults with dyslexia to scans of typical readers in the same age groups. Rather than activity in isolated brain regions, we looked at functional connectivity, or coordinated fluctuations between pairs of brain regions over time," explained Finn.
In total, they recruited and scanned 75 children and 104 adults. Finn and her colleagues then compared the whole-brain connectivity profiles of the dyslexic readers to the non-impaired readers, which revealed widespread differences.
Dyslexic readers showed decreased connectivity within the visual pathway as well as between visual and prefrontal regions, increased right-hemisphere connectivity, reduced connectivity in the visual word-form area, and persistent connectivity to anterior language regions around the inferior frontal gyrus. This altered connectivity profile is consistent with dyslexia-related reading difficulties.
Dr. John Krystal, Editor of Biological Psychiatry, said, “This study elegantly illustrates the value of functional imaging to map circuits underlying problems with cognition and perception, in this case, dyslexia.”
"As far as we know, this is one of the first studies of dyslexia to examine differences in functional connectivity across the whole brain, shedding light on the brain networks that crucially support the complex task of reading," added Finn. "Compared to typical readers, dyslexic readers had weaker connections between areas that process visual information and areas that control attention, suggesting that individuals with dyslexia are less able to focus on printed words."
Additionally, young-adult dyslexic readers maintained high connectivity to brain regions involved in phonology, suggesting that they continue to rely on effortful “sounding out” strategies into adulthood rather than transitioning to more automatic, visual-based strategies for word recognition.
A better understanding of brain organization in dyslexia could potentially lead to better interventions to help struggling readers.
(Source: elsevier.com)
Researchers publish first study of brain activation in MS using fNIRS
Using functional near infrared spectroscopy (fNIRS), Kessler Foundation researchers have shown differential brain activation patterns between people with multiple sclerosis (MS) and healthy controls. This is the first MS study in which brain activation was studied using fNIRS while participants performed a cognitive task. The article, “Neuroimaging and cognition using functional near infrared spectroscopy (fNIRS) in multiple sclerosis,” was published online on June 11 by Brain Imaging and Behavior. Authors are Jelena Stojanovic-Radic, PhD, Glenn Wylie, DPhil, Gerald Voelbel, PhD, Nancy Chiaravalloti, PhD, and John DeLuca, PhD.
Researchers compared 13 individuals with MS with 12 controls for their performance on a working memory task with four levels of difficulty. Most such studies have employed functional magnetic resonance imaging (fMRI); fNIRS has been used infrequently in clinical populations, and has not been applied previously to neuroimaging research in MS. Studies comparing fMRI findings with those of fNIRS, however, show broad agreement in terms of activation patterns.
Results showed differences in activation between the groups that were dependent on task load. The MS group had an increase in activation at low task difficulty and a decrease in activation at high task difficulty. Conversely, in the control group, activation decreased with low task difficulty and increased with high task difficulty. Performance accuracy was lower in the MS group for low task load; there were no differences between the groups at the higher task loads.
“The data we obtained via fNIRS are consistent with fMRI data for clinical populations. We demonstrated that fNIRS is capable of detecting neuronal activation with a reasonable degree of detail,” noted Glenn Wylie, DPhil, associate director of Neuroscience and the Neuroimaging Center at Kessler Foundation. “We attribute the differences in brain activation patterns to the effort expended during the working memory task rather than to differences in speed of processing,” he added. “Because fNIRS is more portable and easier to use that fMRI, it may offer advantages in monitoring cognitive interventions that require frequent scans.”
In addition to working memory, future research in clinical populations should focus on processing speed and episodic memory, cognitive functions that are also affected in MS.
Neuroscientists watch imagination happening in the brain
“You may say I’m a dreamer, but I’m not the only one,” sang John Lennon in his 1971 song Imagine.
And thanks to the dreams of a BYU student, we now know more about where and how imagination happens in our brains.
Stefania Ashby and her faculty mentor devised experiments using MRI technology that would help them distinguish pure imagination from related processes like remembering.
“I was thinking a lot about planning for my own future and imagining myself in the future, and I started wondering how memory and imagination work together,” Ashby said. “I wondered if they were separate or if imagination is just taking past memories and combining them in different ways to form something I’ve never experienced before.”
There’s a bit of scientific debate over whether memory and imagination truly are distinct processes. So Ashby and her faculty mentor devised MRI experiments to put it to the test.
They asked study participants to provide 60 personal photographs for the “remember” section of the experiment. Participants also filled out a questionnaire beforehand to determine which scenarios would be unfamiliar to them and thus a better fit for the “imagine” section.
The researchers then showed people their own photographs during an MRI session to elicit brain activity that is strictly memory-based. A statistical analysis revealed distinctive patterns for memory and imagination.
“We were able to see the distinctions even in those small regions of the hippocampus,” Ashby said. “It’s really neat that we can see the difference between those two tasks in that small of a brain region.”
Ashby co-authored the study with BYU psychology and neuroscience professor Brock Kirwan for the journal Cognitive Neuroscience. Kirwan studies memory at Brigham Young University, and Ashby is one of many students that he has mentored.
“Stefania came in really excited about this project, she pitched it to me, and basically sold it to me right there,” Kirwan said. “It was really cool because it gave me a chance to become more immersed and really broaden my horizons.”
Stefania graduated in 2011 and is currently working as a research associate at UC Davis, where she uses neuroimaging to study individuals at risk of psychotic disorders such as schizophrenia. Her plan is to earn a Ph.D. in neuroscience and continue researching.
Electric Current to Brain Boosts Memory
Stimulating a particular region in the brain via non-invasive delivery of electrical current using magnetic pulses, called Transcranial Magnetic Stimulation, improves memory, reports a new Northwestern Medicine® study.
The discovery opens a new field of possibilities for treating memory impairments caused by conditions such as stroke, early-stage Alzheimer’s disease, traumatic brain injury, cardiac arrest and the memory problems that occur in healthy aging.
“We show for the first time that you can specifically change memory functions of the brain in adults without surgery or drugs, which have not proven effective,” said senior author Joel Voss, assistant professor of medical social sciences at Northwestern University Feinberg School of Medicine. “This noninvasive stimulation improves the ability to learn new things. It has tremendous potential for treating memory disorders.”
The study was published August 29 in Science.
The study also is the first to demonstrate that remembering events requires a collection of many brain regions to work in concert with a key memory structure called the hippocampus – similar to a symphony orchestra. The electrical stimulation is like giving the brain regions a more talented conductor so they play in closer synchrony.
“It’s like we replaced their normal conductor with Muti,” Voss said, referring to Riccardo Muti, the music director of the renowned Chicago Symphony Orchestra. “The brain regions played together better after the stimulation.”
The approach also has potential for treating mental disorders such as schizophrenia in which these brain regions and the hippocampus are out of sync with each other, affecting memory and cognition.
TMS Boosts Memory
The Northwestern study is the first to show TMS improves memory long after treatment. In the past, TMS has been used in a limited way to temporarily change brain function to improve performance during a test, for example, making someone push a button slightly faster while the brain is being stimulated. The study shows that TMS can be used to improve memory for events at least 24 hours after the stimulation is given.
Finding the Sweet Spot
It isn’t possible to directly stimulate the hippocampus with TMS because it’s too deep in the brain for the magnetic fields to penetrate. So, using an MRI scan, Voss and colleagues identified a superficial brain region a mere centimeter from the surface of the skull with high connectivity to the hippocampus. He wanted to see if directing the stimulation to this spot would in turn stimulate the hippocampus. It did.
“I was astonished to see that it worked so specifically,” Voss said.
When TMS was used to stimulate this spot, regions in the brain involved with the hippocampus became more synchronized with each other, as indicated by data taken while subjects were inside an MRI machine, which records the blood flow in the brain as an indirect measure of neuronal activity.
The more those regions worked together due to the stimulation, the better people were able to learn new information.
How the Study Worked
Scientists recruited 16 healthy adults ages 21 to 40. Each had a detailed anatomical image taken of his or her brain as well as 10 minutes of recording brain activity while lying quietly inside an MRI scanner. Doing this allowed the researchers to identify each person’s network of brain structures that are involved in memory and well connected to the hippocampus. The structures are slightly different in each person and may vary in location by as much as a few centimeters.
“To properly target the stimulation, we had to identify the structures in each person’s brain space because everyone’s brain is different,” Voss said.
Each participant then underwent a memory test, consisting of a set of arbitrary associations between faces and words that they were asked to learn and remember. After establishing their baseline ability to perform on this memory task, participants received brain stimulation 20 minutes a day for five consecutive days.
During the week they also received additional MRI scans and tests of their ability to remember new sets of arbitrary word and face parings to see how their memory changed as a result of the stimulation. Then, at least 24 hours after the final stimulation, they were tested again.
At least one week later, the same experiment was repeated but with a fake placebo stimulation. The order of real stimulation and placebo portions of the study was reversed for half of the participants, and they weren’t told which was which.
Both groups performed better on memory tests as a result of the brain stimulation. It took three days of stimulation before they improved.
“They remembered more face-word pairings after the stimulation than before, which means their learning ability improved,” Voss said. “That didn’t happen for the placebo condition or in another control experiment with additional subjects.”
In addition, the MRI showed the stimulation caused the brain regions to become more synchronized with each other and the hippocampus. The greater the improvement in the synchronicity or connectivity between specific parts of the network, the better the performance on the memory test. “The more certain brain regions worked together because of the stimulation, the more people were able to learn face-word pairings, “ Voss said.
Using TMS to stimulate memory has multiple advantages, noted first author Jane Wang, a postdoctoral fellow in Voss’s lab at Feinberg. “No medication could be as specific as TMS for these memory networks,” Wang said. “There are a lot of different targets and it’s not easy to come up with any one receptor that’s involved in memory.”
The Future
“This opens up a whole new area for treatment studies where we will try to see if we can improve function in people who really need it,“ Voss said.
His current study was with people who had normal memory, in whom he wouldn’t expect to see a big improvement because their brains are already working effectively.
“But for a person with brain damage or a memory disorder, those networks are disrupted so even a small change could translate into gains in their function,” Voss said.
In an upcoming trial, Voss will study the electrical stimulation’s effect on people with early-stage memory loss.
Voss cautioned that years of research are needed to determine whether this approach is safe or effective for patients with Alzheimer’s disease or similar disorders of memory.