Posts tagged brain mapping
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.
Well-connected hemispheres of Einstein’s brain may have sparked brilliance
The left and right hemispheres of Albert Einstein’s brain were unusually well connected to each other and may have contributed to his brilliance, according to a new study conducted in part by Florida State University evolutionary anthropologist Dean Falk.
"This study, more than any other to date, really gets at the ‘inside’ of Einstein’s brain," Falk said. "It provides new information that helps make sense of what is known about the surface of Einstein’s brain."
The study, “The Corpus Callosum of Albert Einstein’s Brain: Another Clue to His High Intelligence,” was published in the journal Brain. Lead author Weiwei Men of East China Normal University’s Department of Physics developed a new technique to conduct the study, which is the first to detail Einstein’s corpus callosum, the brain’s largest bundle of fibers that connects the two cerebral hemispheres and facilitates interhemispheric communication.
"This technique should be of interest to other researchers who study the brain’s all-important internal connectivity," Falk said.
Men’s technique measures and color-codes the varying thicknesses of subdivisions of the corpus callosum along its length, where nerves cross from one side of the brain to the other. These thicknesses indicate the number of nerves that cross and therefore how “connected” the two sides of the brain are in particular regions, which facilitate different functions depending on where the fibers cross along the length. For example, movement of the hands is represented toward the front and mental arithmetic along the back.
In particular, this new technique permitted registration and comparison of Einstein’s measurements with those of two samples — one of 15 elderly men and one of 52 men Einstein’s age in 1905. During his so-called “miracle year” at 26 years old, Einstein published four articles that contributed substantially to the foundation of modern physics and changed the world’s views about space, time, mass and energy.
The research team’s findings show that Einstein had more extensive connections between certain parts of his cerebral hemispheres compared to both younger and older control groups.
The research of Einstein’s corpus callosum was initiated by Men, who requested the high-resolution photographs that Falk and other researchers published in 2012 of the inside surfaces of the two halves of Einstein’s brain. In addition to Men, the current research team included Falk, who served as second author; Tao Sun of the Washington University School of Medicine; and, from East China Normal University’s Department of Physics, Weibo Chen, Jianqi Li, Dazhi Yin, Lili Zang and Mingxia Fan.
(Image: National Museum of Health and Medicine)
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.
Researchers identify the neural circuits that modulate REM sleep
A team of scientists led by Dr. Antoine Adamantidis, a researcher at the Douglas Mental Health University Institute and an assistant professor at McGill University, has released the findings from their latest study, which will appear in the October issue of the prestigious scientific journal Nature Neuroscience.
(Image: iStockphoto)
Previous studies had established an association between the activity of certain types of neurons and the phase of sleep known as REM (rapid eye movement). Researchers on the team of Dr. Antoine Adamantidis identified, for the first time, a precise causal link between neuronal activity in the lateral hypothalamus (LH) and the state of REM sleep. Using optogenetics, they were able to induce REM sleep in mice and modulate the duration of this sleep phase by activating the neuronal network in this area of the brain.
This achievement is an important contribution to the understanding of sleep mechanisms in the brains of mammals, as well as the underlying neuronal network, which is still not well understood despite recent breakthroughs in neuroscience.
Better understanding how sleep is modulated to reduce sleep disorders
“These research findings could help us better grasp how the brain controls sleep and better understand the role of sleep in humans. These results could also lead to new therapeutic strategies to treat sleep disorders along with associated neuropsychiatric problems,” stated Dr. Antoine Adamantidis, who is also the Canada Research Chair in Neural Circuits and Optogenetics.
What is REM (rapid eye movement) sleep?
There are two types of sleep: REM and non-REM sleep. In humans, non-REM sleep has four stages. REM sleep, or deep sleep, is generally associated with dreaming and is a phase when the brain is very active, even though people are in a heavy sleep, their eyes move rapidly (hence the name), and their bodies have an almost total loss of muscle tonus.
Although our understanding of the mechanisms that control the wake and sleep cycle has progressed in recent years, many frontiers remain unexplored. However, we do know that a disruption in sleep can lead to adverse effects on physical and mental health in humans.
Optogenetics, a revolutionary technology
In 2010 in the journal Nature, optogenetics was recognized as one of the coming decade’s most promising techniques to better understand brain function. This new field of research and application integrates optics and genetics methodologies to modulate the activity of neural circuits. Optogenetics involves controlling neuronal activity with light. This technique is therefore used to manipulate a specific type of cell without affecting neighbouring cells. A researcher who uses optogenetics is therefore like a conductor who decides to change the sheet music for an instrument to observe the effects, however insignificant they may seem, on the orchestra’s entire performance.
(Source: douglas.qc.ca)
Decoding Sounds’ Source: Researchers Unravel Part of Mystery
As Baby Boomers age, many experience difficulty in hearing and understanding conversations in noisy environments such as restaurants. People who are hearing-impaired and who wear hearing aids or cochlear implants are even more severely impacted. Researchers know that the ability to locate the source of a sound with ease is vital to hear well in these types of situations, but much more information is needed to understand how hearing works to be able to design devices that work better in noisy environment.
Researchers from the Eaton-Peabody Laboratories of the Massachusetts Eye and Ear, Harvard Medical School, and Research Laboratory of Electronics, Massachusetts Institute of Technology have gained new insight into how localized hearing works in the brain. Their research is published in the Oct. 2, 2013 issue of the Journal of Neuroscience.
“Most people are able to locate the source of a sound with ease, for example, a snapping twig on the left, or a honking horn on the right. However this is actually a difficult problem for the brain to solve,” said Mitchell L. Day, Ph.D., investigator in the Eaton-Peabody Laboratories at Mass. Eye and Ear and instructor of Otology and Laryngology at Harvard Medical School “The higher levels of the brain that decide the direction a sound is coming from do not have access to the actual sound, but only the representation of that sound in the electrical activity of neurons at lower levels in the brain. How higher levels of the brain use information contained in the electrical activity of these lower-level neurons to create the perception of sound location is not known.”
In the experiment, researchers recorded the electrical activity of individual neurons in an essential lower-level auditory brain area called the inferior colliculus (IC) while an animal listened to sounds coming from different directions. They found that the location of a sound source could be accurately predicted from the pattern of activation across a population of less than 100 IC neurons – i.e., a particular pattern of IC activation indicated a particular location in space. Researchers further found that the pattern of IC activation could correctly distinguish whether there was a single sound source present or two sources coming from different directions – i.e., the pattern of IC activation could segregate concurrent sources.
“Our results show that higher levels of the brain may be able to accurately segregate and localize sound sources based on the detection of patterns in a relatively small population of IC neurons,” said Dr. Day. “We hope to learn more so that someday we can design devices that work better in noisy environments.”
(Source: masseyeandear.org)
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)
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.”
Building the best brain: U-M researchers show how brain cell connections get cemented early in life
Research on synapse stabilization could aid understanding of autism, schizophrenia, intellectual disability
When we’re born, our brains aren’t very organized. Every brain cell talks to lots of other nearby cells, sending and receiving signals across connections called synapses.
But as we grow and learn, things get a bit more stable. The brain pathways that will serve us our whole lives start to organize, and less-active, inefficient synapses shut down.
But why and how does this happen? And what happens when it doesn’t go normally? New research from the University of Michigan Medical School may help explain.
In a new paper in Nature Neuroscience, a team of U-M neuroscientists reports important findings about how brain cells called neurons keep their most active connections with other cells, while letting other synapses lapse.
Specifically, they show that SIRP alpha, a protein found on the surface of various cells throughout the body, appears to play a key role in the process of cementing the most active synaptic connections between brain cells. The research, done in mouse brains, was funded by the National Institutes of Health and several foundations.
The findings boost understanding of basic brain development – and may aid research on conditions like autism, schizophrenia, epilepsy and intellectual disability, all of which have some basis in abnormal synapse function.
“For the brain to be really functional, we need to keep the most active and most efficient connections,” says senior author Hisashi Umemori, M.D., Ph.D., a research assistant professor at U-M’s Molecular and Behavioral Neuroscience Institute and assistant professor of biological chemistry in the Medical School. “So, during development it’s crucial to establish efficient connections, and to eliminate inactive ones. We have identified a key molecular mechanism that the brain uses to stabilize and maturate the most active connections.”
Umemori says the new findings on SIRP alpha grew directly out of previous work on competition between neurons, which enables the most active ones to become part of pathways and circuits. (Read more on this research)
The team suspected that there must be some sort of signal between the two cells on either side of each synapse — something that causes the most active synapses to stabilize. So they set out to find out what it was.
SIRP-rise findings
The group had previously shown that SIRP-alpha was involved in some way in a neuron’s ability to form a presynaptic nerve terminal – an extension of the cell that reaches out toward a neighboring cell, and can send the chemical signals that brain cells use to talk to one another.
SIRP-alpha is also already known to serve an important function in the rest of the body – essentially, helping normal cells tell the immune system not to attack them. It may also help cancer cells evade detection by the immune system’s watchdogs.
In the new study, the team studied SIRP alpha function in the brain – and started to understand its role in synapse stabilization. They focused on the hippocampus, a region of the brain very important to learning and memory.
Through a range of experiments, they showed that when a brain cell receives signals from a neighboring cell across a synapse, it actually releases SIRP-alpha into the space between the cells. It does this through the action of molecules inside the cell – called CaMK and MMP – that act like molecular scissors, cutting a SIRP-alpha protein in half so that it can float freely away from the cell.
The part of the SIRP-alpha protein that floats into the synapse “gap” latches on to a receptor on the other side, called a CD47 receptor. This binding, in turn, appears to tell the cell that the signal it sent earlier was indeed received – and that the synapse is a good one. So, the cell brings more chemical signaling molecules down that way, and releases them into the synapse.
As more and more nerve messages travel between the “sending” and “receiving” cells on either side of that synapse, more SIRP-alpha gets cleaved, released into the synapse, and bound to CD47.
The researchers believe this repeated process is what helps the cells determine which synapses to keep – and which to let wither.
Umemori says the team next wants to look at what happens when SIRP-alpha doesn’t get cleaved as it should – and at what’s happening in cells when a synapse gets eliminated.
“This step of shedding SIRP-alpha must be critical to developing a functional neural network,” he says. “And if it’s not done well, disease or disorders may result. Perhaps we can use this knowledge to treat diseases caused by defects in synapse formation.”
He notes that the gene for the CD47 receptor is found in the same general area of our DNA as several genes that are suspected to be involved in schizophrenia.
Ten-Year Project Redraws the Map of Bird Brains
Gene expression analysis shows bird brain an even better model for research.
Explorers need good maps, which they often end up drawing themselves.
Pursuing their interests in using the brains of birds as a model for the human brain, an international team of researchers led by Duke neuroscientist Erich Jarvis and his collaborators Chun-Chun Chen and Kazuhiro Wada have just completed a mapping of the bird brain based on a 10-year exploration of the tiny cerebrums of eight species of birds.
In a special issue appearing online in the Journal of Comparative Neurology, two papers (1, 2) from the Jarvis group propose a dramatic redrawing of some boundaries and functional areas based on a computational analysis of the activity of 52 genes across 23 areas of the bird brain.
Jarvis, who is a professor of neurobiology at Duke, member of the Duke Institute for Brain Sciences, and a Howard Hughes Medical Institute investigator, said the most important takeaway from the new map is that the brains of all vertebrates, a group that includes birds as well as humans, have some important similarities that can be useful to research.
Most significantly, the new map argues for and supports the existence of columnar organization in the bird brain. “Columnar organization is a rule, rather than an exception found only in mammals,” Jarvis said. “One way I visualize this view is that the avian brain is one big, giant gyrus folding around a ventricle space, functioning like what you’d find in the mammalian brain,” he said.
To create different patterns of gene expression for the analysis, the birds were exposed to various environmental factors such as darkness or light, silence or bird song, hopping on a treadmill, and in the case of migratory warblers, a magnetic field that stimulated their navigational circuits.
The new map follows up on a 2004 model, proposed by an Avian Brain Nomenclature Consortium, also lead by Jarvis and colleagues, which officially changed a century-old view on the prevailing model that the avian brain contained mostly primitive regions. They argued instead that the avian brain has a cortical-like area and other forebrain regions similar to mammals, but organized differently.
"The change in terminology is small this time, but the change in concept is big," Jarvis said. For this special issue, the of Journal of Comparative Neurology commissioned a commentary by Juan Montiel and Zoltan Molnar, experts in brain evolution, to summarize the large amount of data presented in the studies by the Jarvis group.
One of the major findings is that two populations of cells on either side of a void called the ventricle are actually the same cell types with similar patterns of gene expression. Earlier investigators had thought of the ventricle as a physical barrier separating cell types, but in development studies led by Jarvis’ post doctoral fellow Chun-chun Chen, the Duke researchers showed how dividing cells spread in a sheet and flow around the ventricle as they multiply.
The new map simplifies the bird cortex, called pallium, from seven populations of cells down to four major populations. Humans have five populations of cells in six layers.
Part of this refinement is simply that the tools are getting better, says Harvey Karten, a professor of neurosciences at the University of California-San Diego who proposed a dramatic re-thinking of bird cortical organization in the late 1960s. The best tools in that era were microscopes, specific cell stains and electrophysiology. Karten and colleagues are authors of a fourth paper in the special issue which announces a database of gene expression profiles of the avian brain containing some of the data that the Jarvis group used.
Jarvis said having a more specific map is necessary for properly sampling cell populations for gene expression analysis to do even more functional analysis of how the brain operates. As a next step, his team is considering doing an even more detailed bird map with “several hundred” genes rather than the 52 used to make this map.
Jarvis and colleagues are working now on a similar mapping of the crocodile brain with the ultimate goal of being able to say something about how dinosaur brains were organized, since both birds and crocs are descended from them. At a Society for Neuroscience conference in November, they’ll be presenting some early findings from that project.
Though the specifics of this newest map may only be of interest within the bird research community, Jarvis said, it builds the awareness that birds can be a useful model for many questions about the human brain.
"Where does the mammalian brain come from?" Karten asks. "And what’s the origin of these structures at the cellular and molecular level?" Some neuroscientists have argued that the mammalian cortex — the one we have — is something apart from the brains of other vertebrates. Jarvis and Karten now think vertebrate brains have more commonalities than differences.
That awareness is making birds an ever more useful model for questions about the human brain. “There are very few animal models where you can learn — at the molecular level — what’s going on in vocal learning,” Karten said. Birds are also being used as models for research on Parkinson’s, Huntington’s, deafness and other degenerative conditions in humans.
(Source: today.duke.edu)
Image: Eleven areas of the brain are showing differential activity levels in a Dartmouth study using functional MRI to measure how humans manipulate mental imagery. Credited to Alex Schlegel, Dartmouth College
Researchers discover how and where imagination occurs in human brains
New insights into ‘mental workspace’ may help advance artificial intelligence
Philosophers and scientists have long puzzled over where human imagination comes from. In other words, what makes humans able to create art, invent tools, think scientifically and perform other incredibly diverse behaviors?
The answer, Dartmouth researchers conclude in a new study, lies in a widespread neural network — the brain’s “mental workspace” — that consciously manipulates images, symbols, ideas and theories and gives humans the laser-like mental focus needed to solve complex problems and come up with new ideas.
Their findings, titled “Network structure and dynamics of the mental workspace,” appear the week of Sept. 16 in the Proceedings of the National Academy of Sciences.
"Our findings move us closer to understanding how the organization of our brains sets us apart from other species and provides such a rich internal playground for us to think freely and creatively," says lead author Alex Schlegel, a graduate student in the Department of Psychological and Brain Sciences. "Understanding these differences will give us insight into where human creativity comes from and possibly allow us to recreate those same creative processes in machines."
Scholars theorize that human imagination requires a widespread neural network in the brain, but evidence for such a “mental workspace” has been difficult to produce with techniques that mainly study brain activity in isolation. Dartmouth researchers addressed the issue by asking: How does the brain allow us to manipulate mental imagery? For instance, imagining a bumblebee with the head of a bull, a seemingly effortless task but one that requires the brain to construct a totally new image and make it appear in our mind’s eye.
In the study, 15 participants were asked to imagine specific abstract visual shapes and then to mentally combine them into new more complex figures or to mentally dismantle them into their separate parts. Researchers measured the participants’ brain activity with functional MRI and found a cortical and subcortical network over a large part of the brain was responsible for their imagery manipulations. The network closely resembles the “mental workspace” that scholars have theorized might be responsible for much of human conscious experience and for the flexible cognitive abilities that humans have evolved.