Posts tagged science
Articles and news from the latest research reports.
Enigmatic Neurons Help Flies Get Oriented
Neurons deep in the fly’s brain tune in to some of the same basic visual features that neurons in bigger animals such as humans pick out in their surroundings. The new research is an important milestone toward understanding how the fly brain extracts relevant information about a visual scene to guide behavior.
As a tiny fruit fly navigates through its environment, it relies on visual landmarks to orient itself. Now, researchers at the Howard Hughes Medical Institute’s Janelia Farm Research Campus have identified neurons deep in the fly’s brain that tune in to some of the same basic visual features that neurons in bigger animals such as humans pick out in their surroundings. The new research is an important milestone toward understanding how the fly brain extracts relevant information about a visual scene to guide behavior.
In Vivek Jayaraman’s lab at Janelia, researchers are studying fly neural circuits with the goal of understanding fundamental principles of information processing. “Our hope is that over time we will get a clear picture of the neural transformations and algorithms involved in creating actions from sensory and motor information,” Vivek says. In a study published October 9, 2013, in the journal Nature, Vivek and postdoctoral researcher Johannes Seelig report on visual representations in a region of the fly brain thought to be important for visual learning.
Researchers have gathered compelling evidence that fruit flies recognize and remember visual features in their environment. Flies can use that information to seek out safe spaces or to avoid uncomfortable ones. Genetic studies have indicated that a region deep in the fly brain called the central complex is critical for these behaviors.
The central complex is found in the brains of insects and some crustaceans. “It’s not purely involved in visual learning, and is quite likely to be broadly important for sensory-motor integration in all these critters,” Vivek says, noting that in butterflies and locusts, the central complex may facilitate the use of polarized light for navigation during migration. Also, studies in cockroaches have found that it is important for turning in response to antennal touch. But in flies, no one had yet examined the activity of the neurons in the central complex to characterize their role. “It really was quite a mystery what was going on in this part of the fly brain,” Seelig says, adding that this study is only one step on a long road.
Technical limitations had prevented researchers from measuring neuronal activity in the fly’s central complex, where neurons are far smaller than they are in larger insects. Available techniques required flies to be immobilized, so scientists were limited to studying parts of the nervous system that detected sensory information, rather than those that processed that information or converted it into motor activity. But in 2010, Seelig and colleagues in Vivek’s lab at Janelia developed a method that enabled them to peer into the interior of a fly’s brain with a two-photon microscope, while the insect maintained the freedom to walk and move its wings. The microscope can detect genetically encoded proteins that light up when a nerve cell fires, due to the surge of calcium ions that accompanies a nerve impulse. “Once we had these tools, we really wanted to apply them to this central brain area,” Seelig says.
Using genetically modified strains of flies, Vivek and Seelig focused their experiments on specific classes of neurons and collected more comprehensive data about the activity of those populations than had been done in other species. They chose to zero in on a class of neurons known as ring neurons, on which the dendrites—the branching structures that connect to neighboring cells—were densely concentrated in specific spots within a region neighboring the central complex.
To test the ring neurons’ response to visual stimuli, Seelig placed the flies into a small virtual reality arena in which the flies could be presented with simple patterns of light. By monitoring the calcium-indicating dyes in the cells, Seelig could visualize nerve activity as each fly was exposed to different stimuli.
The researchers found that each neuron responded to visual stimuli in specific regions of the fly’s field of view. “Each cell seemed to have its receptive field in a slightly different area of that space,” Vivek explains. Further, they found that the orientation of the patterns that they projected onto the walls of the arena influenced the ring cells’ response: for example, vertical bars elicited a stronger response than horizontal bars for most cells.
Flies have an innate tendency to walk or fly toward vertically-oriented stimuli, but Vivek and Seelig were nonetheless surprised by the ring neurons’ strong bias towards detecting such patterns. Further, Seelig says, this preference for specific orientations parallels what others have found in larger animals. Neurons in the primary visual cortex of mammalian brains known as simple cells function similarly—identifying basic visual patterns and being tuned to their orientation. “A wide range of visual animals seem to use the same basic feature set when they break down the visual scene,” Vivek says, explaining that in humans, such simple features are combined by later brain regions into increasingly complex ones to eventually produce representations for faces.
He says it is not clear whether fruit flies reassemble the features in their visual field in the same way, or whether basic representations are instead converted directly into guidance for actions. “It’s an open question how complex a shape a fly needs to recognize and respond to,” he says.
The scientists also found that the ring neurons responded similarly to the visual environment regardless of whether the flies were stationary or walking. Flying diminished the response somewhat, but overall, Seelig says, visual patterns influenced the neurons’ activity far more than the insects’ behavior. “These particular neurons seem to filter out visual features, then send that information to other parts of the central complex that may transform that information into a behavioral signal. So this may be one of the major entry points for visual information to the region,” says Seelig.
Determining what happens next to the information received by ring neurons is an important question for Vivek and Seelig, who say they will expand their studies by testing the activity of other neurons in the central complex. “By marching through these networks, we hope to begin to understand how sensory information is integrated to make motor decisions,” Vivek explains.
Studying the social side of carnivores
The part of the brain that makes humans and primates social creatures may play a similar role in carnivores, according to a growing body of research by a Michigan State University neuroscientist.
In studying spotted hyenas, lions and, most recently, the raccoon family, Sharleen Sakai has found a correlation between the size of the animals’ frontal cortex and their social nature.
In her latest study, Sakai examined the digitally recreated brains of three species in the Procyonid family – the raccoon, the coatimundi and the kinkajou – and found the coatimundi had the largest frontal cortex. The frontal cortex is thought to regulate social interaction, and the coatimundi is by far the most social of the three animals, often living in bands of 20 or more.
The study, funded by the National Science Foundation, is published in the research journal Brain, Behavior and Evolution.
“Most neuroscience research that looks at how brains evolve has focused primarily on primates, so nobody really knows what the frontal cortex in a carnivore does,” said Sakai, professor of psychology. “These findings suggest the frontal cortex is processing social information in carnivores perhaps similar to what we’ve seen in monkeys and humans.”
Sakai did the most recent study in her neuroscience lab with Bradley Arsznov, a former MSU doctoral student who’s now an assistant professor of psychology at Minnesota State University. Sakai is one of myriad MSU faculty members who help make the university’s brain research portfolio one of the most diverse in the nation.
Her latest study was based on the findings from 45 adult Procyonid skulls acquired from university museum collections (17 coatimundis, 14 raccoons and 14 kinkajous). The researchers used computed tomography, or CT scans, and sophisticated software to digitally “fill in” the areas where the brains would have been.
When they analyzed into the findings, they discovered the female coatimundi had the largest anterior cerebrum volume consisting mainly of the frontal cortex, which regulates social activity in primates. This makes sense, Sakai said, since the female coatimundi is highly social while the male coatimundi, once grown, typically lives on its own or with another male. Also known as the Brazilian aardvark, the coatimundi – or coati – is native to Central and South America.
Raccoons, the most solitary of the three animals, had the smallest frontal cortex. However, raccoons had the largest posterior cerebrum, which contains the sensory area related to forepaw sensation and dexterity – and the raccoon’s forepaws are extremely dexterous and highly sensitive.
The rainforest-dwelling kinkajou had the largest cerebellum and brain stem, areas that regulate motor coordination. This skill is crucial for animals like the kinkajou that live in trees.
Brain size variations in this small family of carnivores appear to be related to differences in behavior including social interaction, Sakai said.
Two genes linked to increased risk for eating disorders
Eating disorders like anorexia nervosa and bulimia often run in families, but identifying specific genes that increase a person’s risk for these complex disorders has proved difficult.
Now scientists from the University of Iowa and University of Texas Southwestern Medical Center have discovered—by studying the genetics of two families severely affected by eating disorders—two gene mutations, one in each family, that are associated with increased risk of developing eating disorders.
Moreover, the new study shows that the two genes interact in the same signaling pathway in the brain, and that the two mutations produce the same biological effect. The findings suggest that this pathway might represent a new target for understanding and potentially treating eating disorders.
"If you’re considering two randomly discovered genes, the chance that they will interact is small. But, what really sealed the deal for us that the association was real was that the mutations have the same effect," says Michael Lutter, UI assistant professor of psychiatry and senior author of the study.
Overall, the study, published Oct. 8 in the Journal of Clinical Investigation, suggests that mutations that decrease the activity of a transcription factor—a protein that turns on the expression of other genes—called estrogen-related receptor alpha (ESRRA) increase the risk of eating disorders.
The challenge of finding genes for complex diseases
Anorexia nervosa and bulimia nervosa are fairly common, especially among women. They affect between 1 and 3 percent of women. They also are among the most lethal of all psychiatric diseases; about 1 in 1,000 women will die from anorexia.
Finding genes associated with complex diseases like eating disorders is challenging. Scientists can analyze the genetics of thousands of people and use statistics to find common, low-risk gene variations, the accumulation of which causes complex disorders from psychiatric conditions like eating disorders to conditions like heart disease or obesity.
On the other end of the spectrum are very rare gene variants, which confer an almost 100 percent risk of getting the disease. To track down these variants, researchers turn to large families that are severely affected by an illness.
Lutter and his colleagues were able to work with two such families to identify the two new genes associated with eating disorders.
"It’s basically a matter of finding out what the people with the disorder share in common that people without the disease don’t have," Lutter explains. "From a theoretical perspective, it’s straightforward. But the difficulty comes in having a large enough group to find these rare genes. You have to have large families to get the statistical power."
In the new study, 20 members from three generations of one family (10 affected individuals and 10 unaffected), and eight members of a second family (six affected and two unaffected) were analyzed.
Two genes, one pathway
The gene discovered in the larger family was ESRRA, a transcription factor that turns on the expression of other genes. The mutation associated with eating disorders decreases ESSRA activity.
The gene found in the second family is a transcriptional repressor called histone deacetylase 4 (HDAC4), which turns off transcription factors, including ESRRA. This mutation is unusual in the sense that it increases the gene’s activity—most mutations decrease or destroy a gene’s activity.
Importantly, the team also found that the two affected proteins interacted with one another; HDAC4 binds to ESRRA and inhibits it.
"The fact that the HDAC4 mutation happens to increase the gene activity and happens to increase its ability to repress the ESSRA protein we found in the other family was just beyond coincidence," Lutter says.
The two genes are already known to be involved in metabolic pathways in muscle and fat tissue. They also are both regulated by exercise.
In the brain, HDAC4 is very important for regulating genes that form connections between neurons. However, there’s almost nothing known about ESRRA in the brain, although it is expressed in many brain regions that are disrupted in anorexia.
Lutter and his colleagues plan to study the role of these genes in mice and in cultured neurons to find out exactly what they are doing in the brain. They will also look for ways to modify the genes’ activity, with the long-term goal of finding small molecules that might be developed into therapies for eating disorders.
They also plan to study patients with eating disorders and see if other genes associated with the ESSRA/HDAC4 brain pathway are affected in humans.
(Source: medicine.uiowa.edu)
Everything in moderation: excessive nerve cell pruning leads to disease
Scientists at the Montreal Neurological Institute and Hospital-The Neuro, McGill University, have made important discoveries about a cellular process that occurs during normal brain development and may play an important role in neurodegenerative diseases. The study’s findings, published in Cell Reports, a leading scientific journal, point to new pathways and targets for novel therapies for Alzheimer’s, Parkinson’s, ALS and other neurodegenerative diseases that affect millions of people world-wide.
Research into neurodegenerative disease has traditionally concentrated on the death of nerve cell bodies. However, it is now certain that in most cases that nerve cell body death represents the final event of an extended disease process. Studies have shown that protecting cell bodies from death has no impact on disease progression whereas blocking preceding axon breakdown has a significant benefit. The new study by researchers at The Neuro shifts the focus to the loss or degeneration of axons, the nerve-cell ‘branches’ that receive and distribute neurochemical signals among neurons.
During early development, axons are pruned to ensure normal growth of the nervous system. Emerging evidence suggests that this pruning process becomes reactivated in neurodegenerative disease, leading to the aberrant loss of axons and dendrites. Axonal pruning in development is significantly influenced by proteins called caspases. “The idea that caspases are even involved in axonal degeneration during development is very recent” said Dr. Philip Barker, a principal investigator at The Neuro and senior author of the study.
Dr. Barker and his colleagues show that the activity of certain ’executioner’ caspases (caspase-3 and caspase-9) induce axonal degeneration and that their action is suppressed by a protein termed XIAP (X-linked inhibitor of apoptosis). “We found that caspase-3- and -9 play crucial roles in axonal degeneration and that their activities are regulated by XIAP. XIAP acts as a brake on caspase activity and must be removed for degeneration to proceed” added Dr. Barker.
This balancing act between caspases and XIAP ensure that caspases do not cause unnecessary or excessive destruction. However, this balance may shift during neurodegenerative disease. “If we understand the pathways that regulate XIAP levels, we may be able to develop therapies that reduce caspase-dependent degeneration during neurodegenerative disease”.
(Source: mcgill.ca)
Brain anatomy and language in young children
Language ability is usually located in the left side of the brain. Researchers studying brain development in young children who were acquiring language expected to see increasing levels of myelin, a nerve fiber insulator, on the left side. They didn’t: The larger myelin structure was already there. Their study underscores the importance of environment in language development.
Researchers from Brown University and King’s College London have gained surprising new insights into how brain anatomy influences language acquisition in young children.
Their study, published in the Journal of Neuroscience, found that the explosion of language acquisition that typically occurs in children between 2 and 4 years old is not reflected in substantial changes in brain asymmetry. Structures that support language ability tend to be localized on the left side of the brain. For that reason, the researchers expected to see more myelin — the fatty material that insulates nerve fibers and helps electrical signals zip around the brain — developing on the left side in children entering the critical period of language acquisition. But that is not what the research showed.
“What we actually saw was that the asymmetry of myelin was there right from the beginning, even in the youngest children in the study, around the age of 1,” said the study’s lead author, Jonathan O’Muircheartaigh, the Sir Henry Wellcome Postdoctoral Fellow at King’s College London. “Rather than increasing, those asymmetries remained pretty constant over time.”
That finding, the researchers say, underscores the importance of environment during this critical period for language.
O’Muircheartaigh is currently working in Brown University’s Advanced Baby Imaging Lab. The lab uses a specialized MRI technique to look at the formation of myelin in babies and toddlers. Babies are born with little myelin, but its growth accelerates rapidly in the first few years of life.
The researchers imaged the brains of 108 children between ages 1 and 6, looking for myelin growth in and around areas of the brain known to support language.
While asymmetry in myelin remained constant over time, the relationship between specific asymmetries and language ability did change, the study found. To investigate that relationship, the researchers compared the brain scans to a battery of language tests given to each child in the study. The comparison showed that asymmetries in different parts of the brain appear to predict language ability at different ages.
“Regions of the brain that weren’t important to successful language in toddlers became more important in older children, about the time they start school,” O’Muircheartaigh said. “As language becomes more complex and children become more proficient, it seems as if they use different regions of the brain to support it.”
Interestingly, the association between asymmetry and language was generally weakest during the critical language period.
“We found that between the ages of 2 and 4, myelin asymmetry doesn’t predict language very well,” O’Muircheartaigh said. “So if it’s not a child’s brain anatomy predicting their language skills, it suggests their environment might be more influential.”
The researchers hope this study will provide a helpful baseline for future research aimed at pinpointing brain structures that might predict developmental disorders.
“Disorders like autism, dyslexia, and ADHD all have specific deficits in language ability,” O’Muircheartaigh said. “Before we do studies looking at abnormalities we need to know how typical children develop. That’s what this study is about.”
“This work is important, as it is the first to investigate the relationship between brain structure and language across early childhood and demonstrate how this relationship changes with age,” said Sean Deoni, assistant professor of engineering, who oversees the Advanced Baby Imaging Lab. “The study highlights the advantage of collaborative work, combining expertise in pediatric imaging at Brown and neuropsychology from the King’s College London Institute of Psychiatry, making this work possible.”
Primate brain development follows a predictable pattern
In a breakthrough for understanding brain evolution, neuroscientists have shown that differences between primate brains - from the tiny marmoset to human – can be largely explained as consequences of the same genetic program.
In research published in the Journal of Neuroscience, Professor Marcello Rosa and his team at Monash University’s School of Biomedical Sciences and colleagues at Universidade Federal do Rio de Janeiro, in Brazil, used computer modelling to demonstrate that the substantial enlargement of some areas of the human brain, vital to advanced cognition, reflected a consistent pattern that is seen across primate species of all sizes.
This finding suggests how the neural circuits responsible for traits that we consider uniquely human – such as the ability to plan, make complex decisions and speak – could have emerged simply as a natural consequence of the evolution of larger brains.
“We have known for a long time that certain areas of the human brain are much larger than one would expect based on how monkey brains are organised,” Professor Rosa said.
“What no one had realised is that this selective enlargement is part of a trend that has been present since the dawn of primates.”
Using publicly available brain maps, MRI imaging data and modelling software, the neuroscientists compared the sizes of different brain areasin humans and three monkey species: marmosets, capuchins and macaques. They found that two regions, the lateral prefrontal cortex and the temporal parietal junction, expand disproportionally to the rest of the brain.
The prefrontal cortex is related to long term planning, personality expression, decision-making, and behaviour modification. The temporal parietal junction is related to self-awareness and self-other distinction.
Lead author Tristan Chaplin, from the Department of Physiology will commence his PhD next year. He said the findings showed that those areas of the brain grew disproportionately in a predictable way.
“We found that the larger the brain is, the larger these areas get,” Tristan said.
“When you go from a small to big monkey - the marmoset to macaque - the prefrontal cortex and temporal parietal junction get larger relative to the rest of the cortex, and we see the same thing again when you compare macaques to humans.”
“This trend argues against the view that specific human mutations gave us these larger areas and advanced cognition and behaviour, but are a consequence of what happens in development when you grow a larger brain,” Tristan said.
Professor Rosa said the pattern held for primate species that evolved completely separately.
"If you compare the capuchin of South America and the macaque of Asia, their brains are almost identical, although they developed on opposite sides of the world. They both reflect the genetic plan of how a primate brain grows," Professor Rosa said.
This is the first computational comparative study conducted across several primate species. Tristan now hopes, in collaboration with zoos, to check if our closest primate relatives, the chimpanzees and gorillas, also have brain areas organised as his theory predicts.
(Source: monash.edu.au)
How Infections in Newborns are Linked to Later Behavior Problems
In animal study, inflammation stops cells from accessing iron needed for brain development
Researchers exploring the link between newborn infections and later behavior and movement problems have found that inflammation in the brain keeps cells from accessing iron that they need to perform a critical role in brain development.
Specific cells in the brain need iron to produce the white matter that ensures efficient communication among cells in the central nervous system. White matter refers to white-colored bundles of myelin, a protective coating on the axons that project from the main body of a brain cell.
The scientists induced a mild E. coli infection in 3-day-old mice. This caused a transient inflammatory response in their brains that was resolved within 72 hours. This brain inflammation, though fleeting, interfered with storage and release of iron, temporarily resulting in reduced iron availability in the brain. When the iron was needed most, it was unavailable, researchers say.
“What’s important is that the timing of the inflammation during brain development switches the brain’s gears from development to trying to deal with inflammation,” said Jonathan Godbout, associate professor of neuroscience at The Ohio State University and senior author of the study. “The consequence of that is this abnormal iron storage by neurons that limits access of iron to the rest of the brain.”
The research is published in the Oct. 9, 2013, issue of The Journal of Neuroscience.
The cells that need iron during this critical period of development are called oligodendrocytes, which produce myelin and wrap it around axons. In the current study, neonatal infection caused neurons to increase their storage of iron, which deprived iron from oligodendrocytes.
In other mice, the scientists confirmed that neonatal E. coli infection was associated with motor coordination problems and hyperactivity two months later – the equivalent to young adulthood in humans. The brains of these same mice contained lower levels of myelin and fewer oligodendrocytes, suggesting that brief reductions in brain-iron availability during early development have long-lasting effects on brain myelination.
The timing of infection in newborn mice generally coincides with the late stages of the third trimester of pregnancy in humans. The myelination process begins during fetal development and continues after birth.
Though other researchers have observed links between newborn infections and effects on myelin and behavior, scientists had not figured out why those associations exist. Godbout’s group focuses on understanding how immune system activation can trigger unexpected interactions between the central nervous system and other parts of the body.
“We’re not the first to show early inflammatory events can change the brain and behavior, but we’re the first to propose a detailed mechanism connecting neonatal inflammation to physiological changes in the central nervous system,” said Daniel McKim, a lead author on the paper and a student in Ohio State’s Neuroscience Graduate Studies Program.
The neonatal infection caused several changes in brain physiology. For example, infected mice had increased inflammatory markers, altered neuronal iron storage, and reduced oligodendrocytes and myelin in their brains. Importantly, the impairments in brain myelination corresponded with behavioral and motor impairments two months after infection.
Though it’s unknown if these movement problems would last a lifetime, McKim noted that “since these impairments lasted into what would be young adulthood in humans, it seems likely to be relatively permanent.”
The reduced myelination linked to movement and behavior issues in this study has also been associated with schizophrenia and autism spectrum disorders in previous work by other scientists, said Godbout, also an investigator in Ohio State’s Institute for Behavioral Medicine Research (IBMR).
“More research in this area could confirm that human behavioral complications can arise from inflammation changing the myelin pattern. Schizophrenia and autism disorders are part of that,” he said.
This current study did not identify potential interventions to prevent these effects of early-life infection. Godbout and colleagues theorize that maternal nutrition – a diet high in antioxidants, for example – might help lower the inflammation in the brain that follows a neonatal infection.
“The prenatal and neonatal period is such an active time of development,” Godbout said. “That’s really the key – these inflammatory challenges during critical points in development seem to have profound effects. We might just want to think more about that clinically.”
Definitive imaging study finds no link between venous narrowing and multiple sclerosis
A study led by Dr. Anthony Traboulsee of the University of British Columbia and Vancouver Coastal Health to see whether narrowing of the veins from the brain to the heart could be a cause of multiple sclerosis has found that the condition is just as prevalent in people without the disease.
The results, published in the U.K. medical journal The Lancet, call into question a controversial theory that MS is associated with a disorder proponents call chronic cerebrospinal venous insufficiency (CCSVI).
The study used both ultrasound and catheter venography (an x-ray of the vein after injecting it with a dye) to examine the veins of people with MS, their unrelated siblings and unrelated healthy volunteers. Catheter venography is considered the most accurate, “gold standard” technology for revealing the size and shape of veins, says Traboulsee, an associate professor of Neurology at UBC and director of the MS Clinic at UBC Hospital of Vancouver Coastal Health.
By comparing the width of veins between the brain and the heart with a normal reference point taken from below the jaw, the researchers showed that at least two-thirds of each of the groups had narrowing of the extracranial veins that was greater than 50 per cent. Differences in rates of venous narrowing between the groups were not statistically significant.
“Our results confirm that venous narrowing is a frequent finding in the general population, and is not a unique anatomical feature associated with multiple sclerosis,” Traboulsee says. “This is the first study to find high rates of venous narrowing in a healthy control group, as well as the first to show that the ultrasound criteria usually used to ‘diagnose’ CCSVI are unreliable. The connection between venous narrowing and MS remains unknown, and it would certainly appear to be much more complicated than current theories suggest.”
Facial Recognition is More Accurate in Photos Showing Whole Person
Subtle body cues allow people to identify others with surprising accuracy when faces are difficult to differentiate. This skill may help researchers improve person-recognition software and expand their understanding of how humans recognize each other.
A study published in Psychological Science by researchers at The University of Texas at Dallas demonstrates that humans rely on non-facial cues, such as body shape and build, to identify people in challenging viewing conditions, such as poor lighting.
“Psychologists and computer scientists have concentrated almost exclusively on the role of the face in person recognition,” explains lead researcher Allyson Rice. “Our results show that the body can also provide important and sometimes sufficient identity information for person recognition.”
During several experiments, researchers asked college-age participants to look at images of two people side-by-side and identify whether the images showed the same person. Some pairs looked similar despite showing different people, while other image pairs showed the same person with a different appearance. The researchers used computer face recognition systems to find pairs of pictures in which facial characteristics were difficult to use for identity.
Overall, participants accurately discerned whether the images showed the same person when they were provided complete images that showed both the face and body. Participants were just as accurate in identifying people in the image pairs when the faces were blocked out and only the bodies were shown. But, similarly to the computer-based face recognition system, participants had trouble identifying images of the subjects’ faces without their bodies.
Image: Above are pairs of photographs that face-recognition software failed to identify correctly. The top two photos are of the same person, while the bottom two photos are of different people
When asked, participants thought they were using primarily facial features to identify the subjects. To unravel the paradox, the researchers used eye-tracking equipment to determine where participants were actually looking. They found participants spent more time looking at the body whenever the face did not provide enough information to identify the subjects.
“People’s recognition strategies were inaccessible to their conscious awareness,” Rice said. “This provides a cautionary tale in ascribing credibility to people’s subjective reports of how they came to an identity decision.”
Dr. Alice O’Toole, Aage and Margareta Møller Professor in the School of Behavioral and Brain Sciences, has worked on facial recognition for over 15 years and supervised the project.
“Given the widespread use of face recognition systems in security settings, it is important for these systems to make use of all potentially helpful information,” O’Toole said. “Our work shows that the body can be surprisingly useful for identification, especially when the face fails to provide the necessary identity information.”
(Source: utdallas.edu)
What evolved first - a dexterous hand or an agile foot?
Resolving a long-standing mystery in human evolution, new research from the RIKEN Brain Science Institute indicates that early hominids developed finger dexterity and tool use ability before the development of bipedal locomotion.
Combining monkey and human behavior, brain imaging, and fossil evidence, a research team led by neurobiologist Dr. Atsushi Iriki and including Dr. Gen Suwa, an anthropologist from the University of Tokyo Museum, have overturned the common assumption that manual dexterity evolved after the development of bipedal locomotion freed hominid hands to use fingers for tool manipulation.
In a study published today in Philosophical Transactions of the Royal Society B, the researchers employed functional magnetic resonance imaging in humans and electrical recording from monkeys to locate the brain areas responsible for touch awareness in individual fingers and toes, called somatotopic maps. With these maps, the researchers confirmed previous studies showing that single digits in the hand and foot have discrete neural locations in both humans and monkeys.
However, the researchers found new evidence that monkey toes are combined into a single map, while human toes are also fused into a single map, but with the prominent exception of the big toe, which has its own map not seen in monkeys. These findings suggest that early hominids evolved dexterous fingers when they were still quadrupeds. Manual dexterity was not further expanded in monkeys, but humans gained fine finger control and a big toe to aid bipedal locomotion.
“In early quadruped hominids, finger control and tool use were feasible, while an independent adaptation involving the use of the big toe for functions like balance and walking occurred with bipedality,” the authors explained.
The brain study was supported by analysis of the well-preserved hand and feet bones of a 4.4 million year-old skeleton of the quadruped hominid Ardipithecus ramidus, a species with hand dexterity that preceded the human-monkey lineage split.
The findings suggest that the parallel evolution of two-legged locomotion and manual dexterity in hands and fingers in the human lineage were a consequence of adaptive pressures on ancestral quadrupeds for balance control by foot digits while retaining the critical capability for fine finger specialization.
“Evolution is not usually thought of as being accessible to study in the laboratory”, stated Dr. Iriki, “but our new method of using comparative brain physiology to decipher ancestral traces of adaptation may allow us to re-examine Darwin’s theories”.