Social Competition May Be Reason For Bigger Brain

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ScienceDaily (June 23, 2009) — For the past 2 million years, the size of the human brain has tripled, growing much faster than other mammals. Examining the reasons for human brain expansion, University of Missouri researchers studied three common hypotheses for brain growth: climate change, ecological demands and social competition. The team found that social competition is the major cause of increased cranial capacity.

To test the three hypotheses, MU researchers collected data from 153 hominid (humans and our ancestors) skulls from the past 2 million years. Examining the locations and global climate changes at the time the fossil was dated, the number of parasites in the region and estimated population density in the areas where the skulls were found, the researchers discovered that population density had the biggest effect on skull size and thus cranial capacity.
"Our findings suggest brain size increases the most in areas with larger populations and this almost certainly increased the intensity of social competition," said David Geary, Curator's Professor and Thomas Jefferson Professor of Psychosocial Sciences in the MU College of Arts and Science. "When humans had to compete for necessities and social status, which allowed better access to these necessities, bigger brains provided an advantage."
The researchers also found some credibility to the climate-change hypothesis, which assumes that global climate change and migrations away from the equator resulted in humans becoming better at coping with climate change. But the importance of coping with climate was much smaller than the importance of coping with other people.
"Brains are metabolically expensive, meaning they take lots of time and energy to develop and maintain, making it so important to understand why our brains continued to evolve faster than other animals," said Drew Bailey, MU graduate student and co-author of the study. "Our research tells us that competition, whether healthy or not, sets the stage for brain evolution."
Journal reference:
David Geary and Drew Bailey. Hominid Brain Evolution. Human Nature, (in press)
Adapted from materials provided by University of Missouri-Columbia.

Brain Detects Happiness More Quickly Than Sadness

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ScienceDaily (June 21, 2009) — Our brains get a first impression of people's overriding social signals after seeing their faces for only 100 milliseconds (0.1 seconds). Whether this impression is correct, however, is another question. Now an international group of experts has carried out an in-depth study into how we process emotional expressions, looking at the pattern of cerebral asymmetry in the perception of positive and negative facial signals.

The researchers worked with 80 psychology students (65 women and 15 men) to analyze the differences between their cerebral hemispheres using the "divided visual field" technique, which is based on the anatomical properties of the visual system.
"What is new about this study is that working in this way ensures that the information is focused on one cerebral hemisphere or the other", J. Antonio Aznar-Casanova, one of the authors of the study and a researcher at the University of Barcelona (UB), tells SINC.
The results, published in the latest issue of the journal Laterality, show that the right hemisphere performs better in processing emotions. "However, this advantage appears to be more evident when it comes to processing happy and surprised faces than sad or frightened ones", the researcher points out.
"Positive expressions, or expressions of approach, are perceived more quickly and more precisely than negative, or withdrawal, ones. So happiness and surprise are processed faster than sadness and fear", explains Aznar-Casanova.
The two faces of the brain
This research study adds to previous ones, which had revealed asymmetries in the way the brain processes emotions, and enriches the international debate in cognitive-emotional neuroscience in terms of how to define the exact way in which human beings process these facial expressions.
People make deductions from the expressions on people's faces. "These inferences can strongly influence election results or the sentences given in trials, and have been studied before in fields such as criminology and the pseudoscience of physiognomy", the neuroscientist tells SINC.
Two theories are currently "competing" to explain the pattern of cerebral asymmetry in processing emotions. The older one postulates the dominance of the right hemisphere in the processing of emotions, while the second is based on the approach-withdrawal hypothesis, which holds that the pattern of cerebral asymmetry depends upon the emotion in question, in other words that each hemisphere is better at processing particular emotions (the right, withdrawal, and the left, approach).
"Today there is scientific evidence in favour of both these theories, but there is a certain consensus in favour of the lateralisation of emotional processing predicted by the approach-withdrawal hypothesis", concludes Aznar-Casanova.
Journal reference:
Alves et al. Patterns of brain asymmetry in the perception of positive and negative facial expressions. Laterality Asymmetries of Body Brain and Cognition, 2008; 14 (3): 256 DOI: 10.1080/13576500802362927
Adapted from materials provided by Plataforma SINC.

First Image Of Memories Being Made

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ScienceDaily (June 19, 2009) — The ability to learn and to establish new memories is essential to our daily existence and identity; enabling us to navigate through the world. A new study by researchers at the Montreal Neurological Institute and Hospital (The Neuro), McGill University and University of California, Los Angeles has captured an image for the first time of a mechanism, specifically protein translation, which underlies long-term memory formation.

The finding provides the first visual evidence that when a new memory is formed new proteins are made locally at the synapse - the connection between nerve cells - increasing the strength of the synaptic connection and reinforcing the memory. The study published in Science, is important for understanding how memory traces are created and the ability to monitor it in real time will allow a detailed understanding of how memories are formed.
When considering what might be going on in the brain at a molecular level two essential properties of memory need to be taken into account. First, because a lot of information needs to be maintained over a long time there has to be some degree of stability. Second, to allow for learning and adaptation the system also needs to be highly flexible.
For this reason, research has focused on synapses which are the main site of exchange and storage in the brain. They form a vast but also constantly fluctuating network of connections whose ability to change and adapt, called synaptic plasticity, may be the fundamental basis of learning and memory.
"But, if this network is constantly changing, the question is how do memories stay put, how are they formed? It has been known for some time that an important step in long-term memory formation is "translation", or the production, of new proteins locally at the synapse, strengthening the synaptic connection in the reinforcement of a memory, which until now has never been imaged," says Dr. Wayne Sossin, neuroscientist at The Neuro and co-investigator in the study. "Using a translational reporter, a fluorescent protein that can be easily detected and tracked, we directly visualized the increased local translation, or protein synthesis, during memory formation. Importantly, this translation was synapse-specific and it required activation of the post-synaptic cell, showing that this step required cooperation between the pre and post-synaptic compartments, the parts of the two neurons that meet at the synapse. Thus highly regulated local translation occurs at synapses during long-term plasticity and requires trans-synaptic signals."
Long-term memory and synaptic plasticity require changes in gene expression and yet can occur in a synapse-specific manner. This study provides evidence that a mechanism that mediates this gene expression during neuronal plasticity involves regulated translation of localized mRNA at stimulated synapses. These findings are instrumental in establishing the molecular processes involved in long-term memory formation and provide insight into diseases involving memory impairment.
This study was funded by the National Institutes of Health, the WM Keck Foundation and the Canadian Institutes of Health Research.
Adapted from materials provided by McGill University, via EurekAlert!, a service of AAAS.

Can Happiness Be Inherited?

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ScienceDaily (May 14, 2009) — A new study suggests that our feelings in our lifetime can affect our children.

Dr. Halabe Bucay suggests that a wide range of chemicals that our brain generates when we are in different moods could affect 'germ cells' (eggs and sperm), the cells that ultimately produce the next generation. Such natural chemicals could affect the way that specific genes are expressed in the germ cells, and hence how a child develops.
In his article in the latest issue of Bioscience Hypotheses, Dr Alberto Halabe Bucay of Research Center Halabe and Darwich, Mexico, suggested that the hormones and chemicals resulting from happiness, depression and other mental states can affect our eggs and sperm, resulting in lasting changes in our children at the time of their conception.
Brain chemicals such as endorphins, and drugs, such as marijuana and heroin are known to have significant effects on sperm and eggs, altering the patterns of genes that are active in them.
"It is well known, of course, that parental behavior affects children, and that the genes that a child gets from its parents help shape that child's character." said Dr. Halabe Bucay. "My paper suggests a way that the parent's psychology before conception can actually affect the child's genes."
"This is an intriguing idea" commented Dr. William Bains, Editor of Bioscience Hypotheses. "We wanted to publish it to see what other scientists thought, and whether others had data that could support or disprove it. That is what our journal is for, to stimulate debate about new ideas, the more groundbreaking, the better."
Journal reference:
Halabe Bucay et al. Endorphins, personality, and inheritance: Establishing the biochemical bases of inheritance. Bioscience Hypotheses, May 7, 2009; DOI: 10.1016/j.bihy.2009.03.003
Adapted from materials provided by Elsevier, via EurekAlert!, a service of AAAS.

Meditation increases brain gray matter

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Push-ups, crunches, gyms, personal trainers -- people have many strategies for building bigger muscles and stronger bones. But what can one do to build a bigger brain? Meditate.

That's the finding from a group of researchers at UCLA who used high-resolution magnetic resonance imaging (MRI) to scan the brains of people who meditate. In a study published in the journal NeuroImage and currently available online (by subscription), the researchers report that certain regions in the brains of long-term meditators were larger than in a similar control group.
Specifically, meditators showed significantly larger volumes of the hippocampus and areas within the orbito-frontal cortex, the thalamus and the inferior temporal gyrus — all regions known for regulating emotions.
"We know that people who consistently meditate have a singular ability to cultivate positive emotions, retain emotional stability and engage in mindful behavior," said Eileen Luders, lead author and a postdoctoral research fellow at the UCLA Laboratory of Neuro Imaging. "The observed differences in brain anatomy might give us a clue why meditators have these exceptional abilities."
Research has confirmed the beneficial aspects of meditation. In addition to having better focus and control over their emotions, many people who meditate regularly have reduced levels of stress and bolstered immune systems. But less is known about the link between meditation and brain structure.
In the study, Luders and her colleagues examined 44 people — 22 control subjects and 22 who had practiced various forms of meditation, including Zazen, Samatha and Vipassana, among others. The amount of time they had practiced ranged from five to 46 years, with an average of 24 years.
More than half of all the meditators said that deep concentration was an essential part of their practice, and most meditated between 10 and 90 minutes every day.
The researchers used a high-resolution, three-dimensional form of MRI and two different approaches to measure differences in brain structure. One approach automatically divides the brain into several regions of interest, allowing researchers to compare the size of certain brain structures. The other segments the brain into different tissue types, allowing researchers to compare the amount of gray matter within specific regions of the brain.

The researchers found significantly larger cerebral measurements in meditators compared with controls, including larger volumes of the right hippocampus and increased gray matter in the right orbito-frontal cortex, the right thalamus and the left inferior temporal lobe. There were no regions where controls had significantly larger volumes or more gray matter than meditators.
Because these areas of the brain are closely linked to emotion, Luders said, "these might be the neuronal underpinnings that give meditators' the outstanding ability to regulate their emotions and allow for well-adjusted responses to whatever life throws their way."
What's not known, she said, and will require further study, are what the specific correlates are on a microscopic level — that is, whether it's an increased number of neurons, the larger size of the neurons or a particular "wiring" pattern meditators may develop that other people don't.
Because this was not a longitudinal study — which would have tracked meditators from the time they began meditating onward — it's possible that the meditators already had more regional gray matter and volume in specific areas; that may have attracted them to meditation in the first place, Luders said.
However, she also noted that numerous previous studies have pointed to the brain's remarkable plasticity and how environmental enrichment has been shown to change brain structure.
Source: University of California - Los Angeles

Brain's Problem-solving Function At Work When We Daydream

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ScienceDaily (May 12, 2009) — A new University of British Columbia study finds that our brains are much more active when we daydream than previously thought.

The study, published in the Proceedings of the National Academy of Sciences, finds that activity in numerous brain regions increases when our minds wander. It also finds that brain areas associated with complex problem-solving – previously thought to go dormant when we daydream – are in fact highly active during these episodes.
"Mind wandering is typically associated with negative things like laziness or inattentiveness," says lead author, Prof. Kalina Christoff, UBC Dept. of Psychology. "But this study shows our brains are very active when we daydream – much more active than when we focus on routine tasks."
For the study, subjects were placed inside an fMRI scanner, where they performed the simple routine task of pushing a button when numbers appear on a screen. The researchers tracked subjects' attentiveness moment-to-moment through brain scans, subjective reports from subjects and by tracking their performance on the task.
The findings suggest that daydreaming – which can occupy as much as one third of our waking lives – is an important cognitive state where we may unconsciously turn our attention from immediate tasks to sort through important problems in our lives.
Until now, the brain's "default network" – which is linked to easy, routine mental activity and includes the medial prefrontal cortex (PFC), the posterior cingulate cortex and the temporoparietal junction – was the only part of the brain thought to be active when our minds wander.
However, the study finds that the brain's "executive network" – associated with high-level, complex problem-solving and including the lateral PFC and the dorsal anterior cingulate cortex – also becomes activated when we daydream.
"This is a surprising finding, that these two brain networks are activated in parallel," says Christoff. "Until now, scientists have thought they operated on an either-or basis – when one was activated, the other was thought to be dormant." The less subjects were aware that their mind was wandering, the more both networks were activated.
The quantity and quality of brain activity suggests that people struggling to solve complicated problems might be better off switching to a simpler task and letting their mind wander.
"When you daydream, you may not be achieving your immediate goal – say reading a book or paying attention in class – but your mind may be taking that time to address more important questions in your life, such as advancing your career or personal relationships," says Christoff.
The research team included members who are now at Stanford University and University of California, Santa Barbara.
Journal reference:
Kalina Christoff, Alan M. Gordon, Jonathan Smallwood, Rachelle Smith, and Jonathan W. Schooler. Experience sampling during fMRI reveals default network and executive system contributions to mind wandering. Proceedings of the National Academy of Sciences, 2009; DOI: 10.1073/pnas.0900234106
Adapted from materials provided by University of British Columbia.

Impaired Brain Plasticity Linked To Angelman Syndrome Learning Deficits

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ScienceDaily (May 10, 2009) — How might disruption of a single gene in the brain cause the severe cognitive deficits associated with Angelman syndrome, a neurogenetic disorder? Researchers at the University of North Carolina at Chapel Hill School of Medicine and Duke University now believe they have the answer: impaired brain plasticity.

"When we have experiences, connections between brain cells are modified so that we can learn," said Benjamin Philpot, Ph.D., professor of cell and molecular physiology at UNC and senior author of the study published online May 10 in Nature Neuroscience. "By strengthening and weakening appropriate connections between brain cells, a process termed 'synaptic plasticity', we are able to constantly learn and adapt to an ever-changing environment."
Angelman syndrome occurs in one in 15,000 live births. The most common genetic defect of the syndrome is the lack of expression of the gene UBE3A on chromosome 15. The syndrome often is misdiagnosed as cerebral palsy or autism. Characteristics of the syndrome include intellectual and developmental delay, severe mental retardation lack of speech (minimal or no use of words), seizures, sleep disturbance, hand flapping and motor and balance disorders.
Philpot and his co-authors studied a mouse model of Angelman syndrome. In these mice, the gene UBE3A is functionally deficient. The study found that brain cells in the mice lacked the ability to appropriately strengthen or weaken their connections in the neocortex, a region of the brain that is important for cognitive abilities.
"If brain cells were unable to modify their connections with new experiences, then we would have difficulty learning," said Michael Ehlers, M.D., Ph.D., professor of neurobiology at Duke and co-senior author of the study. "We have found that a specific form of brain plasticity is severely impaired in a mouse model of Angelman syndrome and this prevents brain circuits from encoding information provided by sensory experiences. In addition, an exciting possibility is that the defect we have found may be a more general feature of other disorders of brain development including autism."
The inability of brain cells to encode information from experiences in the Angelman syndrome model suggests that this is the basis for the learning difficulties in these patients.
"It is difficult to study how experiences lead to changes in the brain in models of mental retardation," said Koji Yashiro, PhD, a former graduate student in Philpot's lab and lead author of the study, now a scientist with Urogenix, Inc. in Research Triangle Park, North Carolina. "Instead of studying a complex learning model, we studied how connections between brain cells change in visual areas of mice exposed to light or kept in darkness. This approach revealed that brain cells in normal mice can modify their connections in response to changes in visual experiences, while the brain cells in Angelman syndrome model mice could not."
An unexpected finding was that the plasticity of the cellular connections could be restored in visual areas of the brain after brief periods of visual deprivation. Philpot said the observation that the brain defect could be reversed "is very encouraging, as it suggests that viable behavioral or pharmacological therapies are likely to exist."
"By showing that brain plasticity can be restored in Angelman syndrome model mice, our findings suggest that brain cells in Angelman syndrome patients maintain a latent ability to express plasticity. We are now collaborating to find a way to tap into this latent plasticity, as this could offer a treatment, or even a cure, for Angelman syndrome," said Philpot.
Philpot added, "This same experimental approach could also reveal how brain cells encode information from experiences in other related disorders, such as autism, and may provide a model to find cures for a variety of neurodevelopmental disorders."
Other authors are, from Philpot's UNC lab: Thorfinn Riday, graduate student; Adam Roberts, Ph.D., postdoctoral fellow; Danilo Bernardo, medical student; and Rohit Prakash, former M.D./Ph.D. rotation student. Kathryn Condon, a graduate student in Ehler's lab and the department of neurobiology at Duke University; and Richard Weinberg, Ph.D., professor of cell and developmental biology at UNC, also participated in the research.
Support for the work came from grants from the National Institutes of Health, the Howard Hughes Medical Institute, the Angelman Syndrome Foundation and the Simons Foundation.
Adapted from materials provided by University of North Carolina School of Medicine, via EurekAlert!, a service of AAAS.