Friday, November 30, 2007

Group Selection, A Theory Whose Time Has Come ... Again

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ScienceDaily (Nov. 29, 2007) — "Although a high standard of morality gives but a slight or no advantage to each individual man and his children over the other men of the same tribe...an advancement in the standard of morality will certainly give an immense advantage to one tribe over another."
With these words, Charles Darwin proposed an evolutionary explanation for morality and pro-social behaviors-- individuals behaving for the good of their group, often at their own expense--that anticipated the future discipline of Sociobiology. A century after this famous passage was published in The Descent of Man (1871), however, Darwin's explanation based on group selection had become taboo and has not recovered since.
Evolutionary scientists David Sloan Wilson and Edward O. Wilson -- whose book Sociobiology:The New Synthesis brought widespread attention to the field in 1975 -- call for an end to forty years of confusion and divergent theories. They propose a new consensus and theoretical foundation that affirms Darwin's original conjecture and is supported by the latest biological findings.
Wilson and Wilson trace much of the confusion in the field to the 1960's, when most evolutionists rejected "for the good of the group" thinking and insisted that all adaptations must be explained in terms of individual self-interest. In an even more reductionistic move, genes were called "the fundamental unit of selection," as if this was an argument against group selection.
Scientific dogma became entrenched in popular culture with the publication of Richard Dawkins' The Selfish Gene (1976). Although evidence in favor of group selection began accumulating almost immediately after its rejection, its taboo status prevented a systematic re-evaluation of the field until now.
Based on current theory and evidence, Wilson and Wilson show that natural selection is unequivocally a multilevel process, as Darwin originally envisioned, and that adaptations can evolve at all levels of the biological hierarchy, from genes to ecosystems.
They conclude with a rallying cry that paraphrases Rabbi Hillel: "Selfishness beats altruism within groups. Altruistic groups beat selfish groups. Everything else is commentary," Wilson and Wilson free sociobiology to once again pursue all lines of inquiry within its discipline.
Journal reference: Wilson, David Sloan and Edward O.Wilson. "Rethinking the Theoretical Foundation of Sociobiology," The Quarterly Review of Biology: December 2007.
Adapted from materials provided by University of Chicago Press Journals.

Fausto Intilla
www.oloscience.com

Thursday, November 29, 2007

Autistic Children May Have Abnormal Functioning Of Mirror Neuron System


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ScienceDaily (Nov. 29, 2007) — Using a novel imaging technique to study autistic children, researchers have found increased gray matter in the brain areas that govern social processing and learning by observation.
"Our findings suggest that the inability of autistic children to relate to people and life situations in an ordinary way may be the result of an abnormally functioning mirror neuron system," said lead author Manzar Ashtari, Ph.D., from the Children's Hospital of Philadelphia in Pennsylvania.
Mirror neurons are brain cells that are active both when an individual is performing an action and experiencing an emotion or sensation, and when that individual witnesses the same actions, emotions and sensations in others. First observed in the macaque monkey, researchers have found evidence of a similar system in humans that facilitates such functions as learning by seeing as well as doing, along with empathizing and understanding the intentions of others. Dr. Ashtari's study found the autistic children had increased gray matter in brain regions of the parietal lobes implicated in the mirror neuron system.
The study included 13 male patients diagnosed with high-functioning autism or Asperger syndrome and an IQ greater than 70 and 12 healthy control adolescents. Average age of the participants was about 11 years. Each of the patients underwent diffusion tensor imaging (DTI), a technique that tracks the movement of water molecules in the brain.
DTI is traditionally used to study the brain's white matter, as well as the brain fibers. However, Dr. Ashtari's team applied it to the assessment of gray matter by employing apparent diffusion coefficient based morphometry (ABM), a new method that highlights brain regions with potential gray matter volume changes. By adding ABM to DTI, the researchers can detect subtle regional or localized changes in the gray matter.
In addition to the gray matter abnormalities linked to the mirror neuron system, the results of this study revealed that the amount of gray matter in the left parietal area correlated with higher IQs in the control group, but not in the autistic children.
"In the normal brain, larger amounts of gray matter are associated with higher IQs," Dr. Ashtari said. "But in the autistic brain, increased gray matter does not correspond to IQ, because this gray matter is not functioning properly."
The autistic children also evidenced a significant decrease of gray matter in the right amygdala region that correlated with severity of social impairment. Children with lower gray matter volumes in this area of the brain had lower scores on reciprocity and social interaction measures.
"Impairments in these areas are the hallmark of autism spectrum disorders, and this finding may lead to greater understanding of the neurobiological underpinnings of the core features of autism," said study co-author Joel Bregman, M.D., medical director of the Fay J. Lindner Center for Autism.
Autism is the fastest growing developmental disability in the United States and typically appears during the first three years of life. Children with autism are hindered in the areas of social interaction and communication skills. According to the Centers for Disease Control and Prevention, as many as 1.5 million Americans have autism.
Results of the study conducted at the Fay J. Lindner Center for Autism, North Shore-Long Island Jewish Health System in Bethpage, N.Y., were presented November 28 at the annual meeting of the Radiological Society of North America.
Co-authors are S. Nichols, Ph.D., C. McIlree, M.S., L. Spritzer, B.S., A. Adesman, M.D., and B. Ardekani, Ph.D.
This study was supported by The Feinstein Institute for Medical Research, North Shore-Long Island Jewish Health System and the National Center for Research Resources/National Institutes of Health.
Adapted from materials provided by Radiological Society of North America.

Fausto Intilla

Pedophilia May Be The Result Of Faulty Brain Wiring

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ScienceDaily (Nov. 29, 2007) — Pedophilia might be the result of faulty connections in the brain, according to new research released by the Centre for Addiction and Mental Health (CAMH). The study used MRIs and a sophisticated computer analysis technique to compare a group of pedophiles with a group of non-sexual criminals. The pedophiles had significantly less of a substance called "white matter" which is responsible for wiring the different parts of the brain together.
The study, published in the Journal of Psychiatry Research, challenges the commonly held belief that pedophilia is brought on by childhood trauma or abuse. This finding is the strongest evidence yet that pedophilia is instead the result of a problem in brain development.
Previous research from this team has strongly hinted that the key to understanding pedophilia might be in how the brain develops. Pedophiles have lower IQs, are three times more likely to be left-handed, and even tend to be physically shorter than non-pedophiles.
"There is nothing in this research that says pedophiles shouldn't be held criminally responsible for their actions," said Dr. James Cantor, CAMH Psychologist and lead scientist of the study, "Not being able to choose your sexual interests doesn't mean you can't choose what you do."
This discovery suggests that much more research attention should be paid to how the brain governs sexual interests. Such information could potentially yield strategies for preventing the development of pedophilia.
A total of 127 men participated in the study; approximately equal numbers of pedophiles and non-sexual offenders.
The Kurt Freund Laboratory at CAMH was established in 1968 and remains one of the world's foremost centres for the research and diagnosis of pedophilia and other sexual disorders.
CAMH is a Pan American Health Organization/World Health Organization Collaborating Centre, and is fully affiliated with the University of Toronto.
Adapted from materials provided by Centre for Addiction and Mental Health.

Fausto Intilla
www.oloscience.com

Tuesday, November 27, 2007

Self-sabotage: Why Some People Can't Handle Success

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ScienceDaily (Nov. 27, 2007) — New research shows that how people view their abilities in the workplace impacts how they respond to success. Dr. Jason Plaks, a social psychologist at the University of Toronto and Kristin Stecher, a research scientist at the University of Washington, found that those who thought of their capabilities as fixed were more likely to become anxious and disoriented when faced with dramatic success, causing their subsequent performance to plummet, compared to those who thought of their abilities as changeable.
"People are driven to feel that they can predict and control their outcomes. So when their performance turns out to violate their predictions, this can be unnerving -- even if the outcome is, objectively speaking, good news," says Plaks. He points out that the notion that people often sacrifice their success in the name of greater certainty has some intuitive appeal but it has never been put to a rigorous test.
In one representative study, Plaks and Stecher used a questionnaire to classify participants into those who endorsed a fixed view of intelligence and those who endorsed a malleable view. Then participants took three versions of what was purported to be an intelligence test. After the first test, all participants were given a lesson on how to improve their score. After the second test, participants were randomly assigned to be told that their performance had improved, stayed constant, or declined.
Among those who believed they had improved, those with the fixed view became more anxious and performed worse on the third test than those with the malleable view. However, among participants who believed that their performance had failed to improve, it was the malleable view participants who grew anxious and underperformed compared to their fixed view counterparts.
Plaks notes that if people gain an understanding of how they view their abilities, as fixed or changeable, then they can be aware of the advantages and pitfalls of both perspectives. This in turn may better equip them to adopt alternative theories to explain life's ups and downs. "Both approaches are highly intuitive and that makes them relatively easy to teach," says Plaks. "If we can get people to change their underlying assumptions about their abilities then they may improve their performance and that is positive news for those charged with the task of getting people to reach their full potential."
The study findings were published in the October issue of the Journal of Personality and Social Psychology.
Adapted from materials provided by University of Toronto.

Fausto Intilla
www.oloscience.com

Monday, November 26, 2007

Simple Retro Toys May Be Better For Children Than Fancy Electronic Toys


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ScienceDaily (Nov. 26, 2007) — The recent recalls of various children’s toys have parents and would-be Santas leery this holiday season, but it may just be the thing to push consumers to be more creative about the toys they buy their young children.
“Old-fashioned retro toys, such as red rubber balls, simple building blocks, clay and crayons, that don’t cost so much and are usually hidden in the back shelves are usually much healthier for children than the electronic educational toys that have fancier boxes and cost $89.99,” says Temple University developmental psychologist Kathy Hirsh-Pasek.
The overarching principle is that children are creative problem-solvers; they’re discoverers; they’re active, says Hirsh-Pasek, the Lefkowitz Professor of Psychology at Temple and co-director of the Temple University Infant Lab. “Your child gets to build his or her imagination around these simpler toys; the toys don’t command what your child does, but your child commands what the toys do.”
As Roberta Golinkoff, head of the Infant Language Project at the University of Delaware says, “Electronic educational toys boast brain development and that they are going to give your child a head start. But developmental psychologists know that it doesn’t really work this way. The toy manufacturers are playing on parents’ fears that our children will be left behind in this global marketplace.”
Golinkoff adds that “kids are not like empty vessels to be filled. If they play with toys that allow them to be explorers, they are more likely to learn important lessons about how to master their world.”
Hirsh-Pasek and Golinkoff, co-authors of Einstein Never Used Flashcards, offer parents the following advice, guidelines, and questions to ask themselves when choosing the proper toys for their young children:
Look for a toy that is 10 percent toy and 90 percent child -- “A lot of these toys direct the play activity of our children by talking to them, singing to them, asking them to press buttons and levers,” Hirsh-Pasek says. “But our children like to figure out what is going on by themselves. I look for a toy that doesn’t command the child, but lets the child command it.”
Toys are meant to be platforms for play -- “Toys should be props for a child’s playing, not engineering or directing the child’s play,” Golinkoff adds. “Toys must awaken the child’s imagination and uniqueness.”
How much can you do with it? -- “If it’s a toy that asks your child to supply one thing, such as fill-in-the-blank or give one right answer, it is not allowing children to express their creativity,” says Hirsh-Pasek. “I look for something that they can take apart and remake or reassemble into something different, which builds their imagination. Toys like these give your child opportunities to ‘make their own worlds.’”
Look to see if the toy promises brain growth -- “Look carefully at the pictures and promises on the box,” Hirsh-Pasek says. “If the toy is promising that your child is going to be smarter, it’s a red flag. If it is promising that your child is going to be bilingual or learn calculus by playing with it, the chances are high that this is not going to happen – even with a tremendous amount of parental intervention.”
Does the toy encourage social interaction? -- “It is fine for your child to have alone time, but it is great for them to be with others,” says Golinkoff. “I always look to see if more than one child can play with the toy at the same time because that’s when kids learn the negotiation skills they need to be successful in life.”
“This advice is not about marketing, but about what we know from 30 years of child psychology about how children learn and how they grow,” says Hirsh-Pasek.
Golinkoff adds, “The irony is that the real educational toys are not the flashy gadgets and gismos with big promises, but the staples that have built creative thinkers for decades.”
Adapted from materials provided by Temple University.

Fausto Intilla

Sunday, November 25, 2007

Is The Beauty Of A Sculpture In The Brain Of The Beholder?


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ScienceDaily (Nov. 24, 2007) — Is there an objective biological basis for the experience of beauty in art? Or is aesthetic experience entirely subjective? This question has been addressed in a new article by Cinzia Di Dio, Emiliano Macaluso and Giacomo Rizzolatti. The researchers used fMRI scans to study the neural activity in subjects with no knowledge of art criticism, who were shown images of Classical and Renaissance sculptures.
The 'objective' perspective was examined by contrasting images of Classical and Renaissance sculptures of canonical proportions, with images of the same sculptures whose proportions were altered to create a comparable degraded aesthetic value. In terms of brain activations, this comparison showed that the presence of the "golden ratio" in the original material activated specific sets of cortical neurons as well as (crucially) the insula, a structure mediating emotions. This response was particularly apparent when participants were only required to observe the stimuli; that is, when the brain reacted most spontaneously to the images presented.
The 'subjective' perspective was evaluated by contrasting beautiful vs. ugly sculptures, this time as judged by each participant who decided whether or not the sculpture was aesthetic. The images judged to be beautiful selectively activated the right amygdala, a structure that responds tolearned incoming information laden with emotional value.
These results indicate that, in observers naïve to art criticism, the sense of beauty is mediated by two non-mutually exclusive processes: one is based on a joint activation of sets of cortical neurons, triggered by parameters intrinsic to the stimuli, and the insula (objective beauty); the other is based on the activation of the amygdala, driven by one's own emotional experiences (subjective beauty). The researchers conclude that both objective and subjective factors intervene in determining our appreciation of an artwork.
The history of art is replete with the constant tension between objective values and subjective judgments. This tension is deepened when artists discover new aesthetic parameters that may appeal for various reasons, be they related to our biological heritage, or simply to fashion or novelty. Still, the central question remains: when the fashion and novelty expire, could their work ever become a permanent patrimony of humankind without a resonance induced by some biologically inherent parameters?
Citation: Di Dio C, Macaluso E, Rizzolatti G (2007) The Golden Beauty: Brain Response to Classical and Renaissance Sculptures. PLoS One 2(11): e1201. doi:10.1371/journal.pone.0001201
Adapted from materials provided by Public Library of Science.

Fausto Intilla

Tuesday, November 20, 2007

How Do We Make Sense Of What We See?


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ScienceDaily (Nov. 20, 2007) — M.C. Escher's ambiguous drawings transfix us: Are those black birds flying against a white sky or white birds soaring out of a black sky? Which side is up on those crazy staircases?
Lines in Escher's drawings can seem to be part of either of two different shapes. How does our brain decide which of those shapes to "see?" In a situation where the visual information provided is ambiguous — whether we are looking at Escher's art or looking at, say, a forest — how do our brains settle on just one interpretation?
In a study published this month in Nature Neuroscience, researchers at The Johns Hopkins University demonstrate that brains do so by way of a mechanism in a region of the visual cortex called V2.
That mechanism, the researchers say, identifies "figure" and "background" regions of an image, provides a structure for paying attention to only one of those two regions at a time and assigns shapes to the collections of foreground "figure" lines that we see.
"What we found is that V2 generates a foreground-background map for each image registered by the eyes," said Rudiger von der Heydt, a neuroscientist, professor in the university's Zanvyl Krieger Mind/Brain Institute and lead author on the paper. "Contours are assigned to the foreground regions, and V2 does this automatically within a tenth of a second."
The study was based on recordings of the activity of nerve cells in the V2 region in the brain of macaques, whose visual systems are much like that of humans. V2 is roughly the size of a microcassette and is located in the very back of the brain. Von der Heydt said the foreground- background "map" generated by V2 also provides the structure for conscious perception in humans.
"Because of their complexity, images of natural scenes generally have many possible interpretations, not just two, like in Escher's drawings," he said. "In most cases, they contain a variety of cues that could be used to identify fore- and background, but oftentimes, these cues contradict each other. The V2 mechanism combines these cues efficiently and provides us immediately with a rough sketch of the scene."
Von der Heydt called the mechanism "primitive" but generally reliable. It can also, he said, be overridden by decision of the conscious mind.
"Our experiments show that the brain can also command the V2 mechanism to interpret the image in another way," he said. "This explains why, in Escher's drawings, we can switch deliberately" to see either the white birds or the dark birds, or to see either side of the staircase as facing "up."
The mechanism revealed by this study is part of a system that enables us to search for objects in cluttered scenes, so we can attend to the object of our choice and even reach out and grasp it.
"We can do all of this without effort, thanks to a neural machine that generates visual object representations in the brain," von der Heydt said. "Better yet, we can access these representations in the way we need for each specific task. Unfortunately, how this machine' works is still a mystery to us. But discovering this mechanism that so efficiently links our attention to figure-ground organization is a step toward understanding this amazing machine."
Understanding how this brain function works is more than just interesting: It also could assist researchers in unraveling the causes of — and perhaps identifying treatment for — visual disorders such as dyslexia.
Other authors include Fangtu T. Qiu and Tadashi Sugihara, both of the Zanvyl Krieger Mind-Brain Institute. Funding for the research was provided by the National Institutes of Health.
Adapted from materials provided by Johns Hopkins University.

Fausto Intilla

Thursday, November 8, 2007

Mirror, Mirror In The Brain: Mirror Neurons, Self-understanding And Autism Research


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ScienceDaily (Nov. 7, 2007) — Recent findings are rapidly expanding researchers' understanding of a new class of brain cells -- mirror neurons -- which are active both when people perform an action and when they watch it being performed.
Some scientists speculate that a mirror system in people forms the basis for social behavior, for our ability to imitate, acquire language, and show empathy and understanding. It also may have played a role in the evolution of speech. Mirror neurons were so named because, by firing both when an animal acts and when it simply watches the same action, they were thought to "mirror" movement, as though the observer itself were acting.
Advances in the past few years have newly defined different types of mirror neurons in monkeys and shown how finely tuned these subsets of mirror neurons can be. New studies also have further characterized abnormal-as well as normal-mirror activity in the brains of children with the social communication disorder known as autism, suggesting new approaches to treatment.
"The tremendous excitement that has been generated in the field by the study of mirror neurons stems from the implications of the findings, which have led to numerous new hypotheses about behavior, human evolution, and neurodevelopmental disorders," says Mahlon DeLong, MD, of Emory University School of Medicine.
Mirror neurons, a class of nerve cells in areas of the brain relaying signals for planning movement and carrying it out, were discovered 11 years ago, an offshoot of studies examining hand and mouth movements in monkeys. Mirror neuron research in the intervening years has expanded into a diverse array of fields. And the implications have been enormous, encompassing evolutionary development, theories of self and mind, and treatments for schizophrenia and stroke.
Findings being presented at Neuroscience 2007 include new research based on work in monkeys, showing that subsets of mirror neurons distinguish between observed actions carried out within hand's reach and those beyond the animal's personal space.
In his study, Peter Thier, PhD, at Tübingen University, first identified a group of mirror neurons by recording single nerve cell activity from electrodes when a monkey gripped different objects and when the monkey watched a person grasp the same objects, both nearby and farther away. About half of the nerve cells that were active when the monkey picked up the objects also sprung into action when it watched a person do so. Thier was assisted by research fellow Antonio Casile and PhD student Vittorio Caggiano, and worked closely with the lab of Giacomo Rizzolatti, MD, at the University of Parma.
They also noticed that some of these confirmed mirror neurons were active only when the monkey was watching activity within its personal space, defined as within reaching distance; others responded only to actions performed in a place outside the monkey's grasp. Thier and colleagues recorded this preferential activity in 22 nerve cells, or together half of the mirror neurons. The other half of the mirror neurons showed activity that did not depend on how close the grasping action was to the monkey.
Although at this stage assigning a functional role is still speculation, Thier suggests this proximity-specific activity in mirror neurons may play an important role when we monitor what goes on around us, or serve as the basis for inferring the intentions of others and for cooperative behavior. "These neurons might encode actions of others that the observers might directly influence, or with which he or she can interact," he says.
Other findings show that mirror neuron activity is instrumental for interpreting the facial expressions and actions of others but may not be sufficient for decoding their thoughts and intentions.
The studies examined changes in certain electroencephalograms (EEG) or brain wave patterns known as mu rhythms, which have a frequency of 8-13 hertz, or oscillations per second. Previous findings based on EEG recordings from the part of the brain that is directly involved in relaying signals for movement and sensing stimuli, known as the sensorimotor cortex, indicate that mu rhythms typically are suppressed by mirror activity in premotor areas of the brain. However, this does not happen in children with autism. As a result, the new work suggests, alternative strategies for reading faces and understanding others develop in the brains of these children.
Pursuing two parallel studies, Jaime Pineda, PhD, at the University of California, San Diego, aimed to contribute evidence supporting one of two theories about the ways we evaluate the actions and intentions of other people-either implicitly or through language-based theoretical concepts.
Using EEG recordings to examine patterns of brain wave activity, Pineda first worked with 23 adults, who were asked to look at photos showing just the eye region of people making various facial expressions. In three separate trials, the subjects were asked to identify either the emotion, race, or gender of the people in the photographs. In a subsequent task, subjects looked at three-panel cartoon strips and were asked to choose a fourth panel that completed the strip-either the conclusion of a series of physical actions or the result of a person interacting with an object. A sequence of a prisoner removing the window of his cell, then looking at his bed, for example, could be followed by a frame of the prisoner asleep, yawning, or using the bedsheet to make a rope. Answering correctly depended on interpreting the cartoon character's intentions appropriately or understanding how physical objects interact.
Pineda repeated the studies with 28 children, 7 to 17 years old, half of whom had autism. The other half were typically developing children.
Recordings from the studies with adults showed a correlation between mu suppression, or mirror neuron activity, and accuracy for both tasks. In fact, the suppression of mu rhythms during the facial expression task also correlated with accuracy in the exercise with the cartoons, suggesting that reading people's expressions and interpreting their intentions may draw from similar activity in the brain.
Recordings from the typically developing children showed similar patterns of suppression during the two tasks, indicating that mirror neuron activity is fully developed by age 7.
In contrast, recordings from the children with autism showed that mu rhythms were enhanced during both tasks. Enhancement is an indication that the mirror neuron system is disengaged. However, because the children still were able to perform the task, Pineda says, "we propose that children with autism develop alternative, non-mirror neuron-based coping strategies for understanding facial expressions and interpreting others' mental states." He suggests that "these compensatory strategies involve inhibition of residual mirror neuron functioning."
These results could be applied to the development of treatments for autism. Pineda and his group have been using neurofeedback training to successfully renormalize functioning in this system. That is, they see mu suppression that is more characteristic of the typically developing brain following such training. "Our findings are consistent with the idea that mirror neurons are not absent in autism," Pineda says, "but rather are abnormally responsive to stimuli and abnormally integrated into wider social-cognitive brain circuits.
"This idea implies that a retraining of mirror neurons to respond appropriately to stimuli and integrate normally into wider circuits may reduce the social symptoms of autism."
Advances in recording brain activity also have made possible findings showing that mirror systems are active even when we are not observing an action with an eye to repeating it.
Suresh Muthukumaraswamy, PhD, at Cardiff University, found that the mirror system is activated when we watch specific actions, even when we are concentrating on a separate task.
The results are based on previous research showing that motor systems in the brain are activated when a person observes an action being performed and on interpretations suggesting that we understand and learn to imitate the actions of others through these brain mechanisms.
Working with 13 adults with an average age of 29, Muthukumaraswamy compared brain activity recorded via magnetoencephalography (MEG). This monitoring technique measures the weak magnetic fields emitted by nerve cells, and, recording from 275 locations, Muthukumaraswamy was able to monitor changes in activity every 600th of a second.
"Although MEG has been in existence for more than 20 years, recent advances in hardware, computing technology, and the algorithms used to analyze the data allow much more detailed analysis of brain function than was previously possible," he says.
Brain activity was recorded as the subjects passively watched a sequence of finger movements, watched the movements knowing they would be asked to repeat them, added up the number of fingers moved as they watched, and performed the sequence of movements themselves.
Results from these recordings showed similar activity when the subjects performed the movement sequence and when they watched someone else do it. In addition, Muthukumaraswamy noted increased activity in areas of the brain regulating motor activity when subjects observed the movements knowing they would later do them, and when they added up the number of fingers used, compared with passive watching.
"These data suggest that activity of human mirror neuron systems is generally increased by attention relative to passive observation, even if that attention is not directed toward a specific motor activity," says Muthukumaraswamy. "Our results suggest that the mirror system remains active regardless of any concurrent task and hence is probably an automatic system.
"A good scientific understanding of the properties of the mirror system in normal humans is important," he adds, "because this may help to understand clinical disorders such as autism where the mirror system may not be functioning normally."
Other findings based on EEG recordings provide the first evidence of normal mirror activity in children with autism: People familiar to children with autism may activate mirror areas of the brain in normal patterns when unfamiliar people do not.
Previous research has shown that mu rhythms are suppressed when a subject identifies with an active person being observed. Based on this work, Lindsay Oberman, PhD, at the University of California, San Diego, examined the role of two separate factors in the mirror system response of children with autism.
Six videos were shown to a group of 26 boys, 8 to 12 years old; half had autism. Three videos showed images representing varying degrees of social interaction: two bouncing balls (the baseline measurement), three people tossing a ball to themselves, and three people throwing the ball to each other and off the screen to the viewer. The other set of videos showed people with varying degrees of familiarity to the subjects: strangers opening and closing their hand, family members making the same hand movement, and the subjects themselves doing the same.
EEG recordings from 13 electrodes in a cap showed that mu activity was suppressed most when subjects watched videos of themselves, indicating the greatest mirror neuron activity. For both groups, the measurements showed a slightly lower level of suppression when subjects watched familiar people in the video and the least when watching strangers. This indicates that normal mirror neuron activity was evoked when children with autism watched family members, but not strangers.
"Thus, to say that the mirror neuron system is nonfunctional may only be partially correct," says Oberman. "Perhaps individuals with autism have fewer mirror neurons and/or less functional mirror neurons that require a greater degree of activation than a typical child's system in order to respond."
The mirror neuron system may react to stimuli that the observer sees as "like me." If this is the case, suggests Oberman, "perhaps typical individuals apply this identification to all people (both familiar and unfamiliar), resulting in activation of these areas in response to the observed stimuli, while individuals on the autism spectrum only consider familiar individuals (including themselves) as 'like me,' " she says.
This evidence for normal mirror neuron activity in autistic children may indicate that mirror system dysfunction in these cases reflects an impairment in identifying with and assigning personal significance to unfamiliar people and things, Oberman suggests. Whether deficits in relating to unfamiliar people that are characteristic of autism are the cause or the result of a dysfunctional mirror neuron system is unclear.
Adapted from materials provided by Society For Neuroscience.

Fausto Intilla

Wednesday, November 7, 2007

Brain Chemical Underpins Social Interaction, And Why People Make Irrational Decisions

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ScienceDaily (Nov. 7, 2007) — New research from the burgeoning field of neuroeconomics examining how people place value on money and other items is helping scientists to decipher how and why people make the decisions they do. Imaging studies of people experiencing real financial losses show activity in brain areas related to processing emotions, a finding that may account for the irrational behavior of financial professionals in high-risk settings. Additional imaging work shows that the same neural network responsible for rationally evaluating risky opportunities is also responsible for the irrational behavior of decision-makers when they face ambiguous situations.
Other research shows that the release of the brain chemical serotonin, which plays a central role in clinical depression, is precisely tuned to various aspects of decision-making and reward-related behavior. New findings also show that the chemical has a significant role in maintaining our social networks, encouraging cooperation and anchoring relationships. These both are findings suggesting that the serotonin brain systems that go awry in depression normally play a critical role in supporting healthy and efficient decision-making.
"Over the course of the last few years, there has been an explosion in our understanding of how humans and animals make decisions," says Paul Glimcher, PhD, of New York University. "Ten years ago, we knew almost nothing about how the human brain weighed costs and benefits to arrive at a choice. Today, there are exciting new discoveries every year. These four studies are examples of just how fast our understanding is growing. And what these studies make clear is that insights from this kind of neuroeconomic research will influence both the structure of our future financial markets and clinical strategies we use to treat mental illness. That's a very cool combination."
New imaging work focuses on our aversion to loss, showing that choices we make when we face losses may rely much more on emotional brain systems than decisions that involve gains of equal, or even greater, size.
Working with 20 undergraduates, PhD student Peter Sokol-Hessner, at New York University, recorded participants' decisions when faced with choices representing various investing scenarios.
Subjects were asked a series of questions as their brain activity was monitored by functional magnetic resonance imaging (fMRI). Sokol-Hessner was able to correlate loss-averse behavior with activity in the amygdala, an area of the brain known to be involved in processing emotions-oftentimes, fear.
"Notably, in contrast to other research, these areas of correlation are not the same as those areas identified as generally active during valuation and decision-making relative to rest, such as the striatum and medial prefrontal cortex," says Sokol-Hessner.
Sokol-Hessner asked his subjects to make two series of 150 choices about how to spend $30. In both series, the subjects chose either to make a risky investing gamble or to settle on a guaranteed amount. For example, the decision might be between a 50-50 gamble in which the participant would either lose $16 or win $25, or the sure choice of $0 (neither winning nor losing a cent). In one series, the subjects evaluated each of the choices independently. For the second, researchers asked them to think "like a trader," evaluating each choice as one in a portfolio of investing decisions. In both cases, they learned the result of each decision immediately.
In a previous version of the study, the researchers had found that "subjects sweat significantly more, per dollar, to losses than gains," says Sokol-Hessner. "This 'over-arousal' correlated with behavioral loss aversion, suggesting a specific role for emotions in choice."
More recently, Sokol-Hessner confirmed results from previous studies showing that as a group, people fear a loss more than they value a gain of an equal amount, but his detailed results showed that, at the individual level, only half his subjects were loss-averse. Equally, about half were not, and some subjects even valued the gain more highly than dreading the loss. He also found substantial variation among his subjects in terms of how much risk they were willing to take and how consistent their decisions were.
Yet no matter their individual profile, Sokol-Hessner found that the subjects made choices that were less loss-averse when they thought about their choices as part of a portfolio. This was true whether or not subjects showed loss-averse tendencies in general.
"These findings are of interest because they shed light on some possible behavioral and neural differences between professional and amateur traders and suggest that the distance between the two can be reduced by something as simple as a cognitive strategy," Sokol-Hessner says.
For future research, Sokol-Hessner may recruit professional traders and compare the biological basis of their investment decision-making. "The integration of methods from economics, psychology, and neuroscience is a signature of neuroeconomic research," he says. "This kind of research has great promise to extend our understanding of how people make decisions and of how they can reliably alter the mechanisms of their own decision-making by taking alternate perspectives on the same choices."
The degree to which we are risk-averse also varies from person to person, as does our tolerance of ambiguity-for example, how much we would prefer a 50 percent chance of winning $20 over an unknown probability of winning $100. This is of particular interest to financial decision-makers because nearly all humans show an irrational aversion to ambiguous investments, even if those investments are likely to perform well. This is true even for individuals who are comfortable with risky investments. But new research using fMRI now indicates these two kinds of decisions in fact rely on activity in the same areas of the brain.
"We know very little about how idiosyncratic risk aversion and ambiguity aversion arise in the human brain," says Ifat Levy, PhD, of New York University. "Indeed, there is not yet even consensus about whether our fear of ambiguous situations reflects the activity of a dedicated brain system or simply a fine-tuning of the systems that represent risk.
"We suggest that neural activation in the basal ganglia and prefrontal cortex serves as a 'common neural currency' for valuing the many different kinds of opportunities we face as human decision-makers."
Working with 10 people, Levy showed her subjects images of jars with red or blue poker chips; they could tell the proportion of red chips in some jars but not others. By drawing a red poker chip, subjects could win money, but the percentage of red chips in the jar, how clear or cloudy the jar was, and the amount of money varied. For each trial, subjects pushed a button to indicate whether they chose to draw a chip or to play a second lottery, in which they had a 50 percent chance of winning $5.
After 360 trials over two sessions, six were played for real money. At the end of the experiment, Levy correlated the brain activity recorded by the imaging scans with objective as well as subjective parameters indicating each subject's preference for risk and ambiguity. Levy found that the same levels of risk-aversion and ambiguity-aversion matched certain patterns of activity in the medial part of the frontal cortex and the basal ganglia, areas known to play a role in decision-making.
"These results cast new light on a growing body of evidence that suggests our brains possess a single, central system for valuing the objects of our decisions in situations ranging from impulsive decision-making to ambiguous investing," says Levy.
"Based upon these data and others, we suggest that this network of brain areas generates the idiosyncratic valuations we place on the options before us, regardless of their nature or the contexts that influence that valuation.
"In other words," she says, "if activity in your prefrontal cortex is strongly affected by risk, ambiguity, delay of gratification, or loss, then that's the kind of person you are."
Recent research with animals shows that the release of the neurotransmitter serotonin is precisely tuned to various aspects and stages of reward-related behavior. Such results may provide a basis for developing more selective medications with fewer side effects for disorders such as depression, obsessive-compulsive disorder, and schizophrenia.
Serotonin acts as on-off switch, controlling various emotional states, and drugs that alter the action of serotonin have been used to treat depression and anxiety disorders for more than a decade. Focusing on the raphe nucleus, the brain region that controls serotonin release, Zachary Mainen, PhD, of Cold Spring Harbor Laboratory, trained rats to associate certain smells with a reward of water. Mainen will be presenting at Neuroscience 2007 at a minisymposium titled "Serotonin and Decision-Making."
On smelling an odor, the rats in the study would react to the scent, poking their noses into one of two holes. When the rat chose the correct hole, it received a drop of water as a reward. Throughout each experiment, comprising several hundred such decisions, Mainen monitored the activity of individual nerve cells in the dorsal raphe nucleus, an area located deep in the brain.
He found that separate subsets of raphe nucleus neurons responded independently to smelling, movement, and reward-related behaviors. In most cases, the nerve cells fired almost immediately-within tens of milliseconds.
Mainen also noticed that raphe nucleus nerve cells fired more when the animal had to ignore distracting sensory information, and stopped firing when it was concentrating on important sensory signals, underscoring a role for serotonin in the feedback loop that adjusts the brain's response to sensory stimulation in healthy individuals.
"Serotonin is a primary target for treatment of depression, anxiety, and other psychiatric disorders, but its function is not well understood," says Mainen. "It is considered particularly enigmatic because it seems to be involved in such a wide variety of brain and behavioral functions.
"These results suggest a specific cellular basis for the diversity of serotonin functions and possible avenues for development of more specific treatments for disorders such as major depression."
Future research will focus on serotonin release in response to more specific behavioral tasks and attempt to distinguish between nerve cells in the raphe nucleus that release serotonin and those that do not.
"These approaches will allow us to stimulate serotonin neurons artificially in order to test their influence on specific behaviors in animals," says Mainen. "In future studies, we would like to examine the impact of psychoactive drugs that target the serotonin system on the firing of different classes of serotonin neurons."
Other findings clarify the role of serotonin in decision-making within a social context: It may encourage cooperative behavior and help solidify social bonds by reinforcing the value we see in others.
Previous work has shown a link between depression and serotonin dysfunction and indicates a role for the neurotransmitter in behavior emphasizing an affiliation between people. Research based on a game called the prisoner's dilemma found that mutual cooperation enhances activity in brain circuits playing a role in reinforcement, indicating that cooperative behavior is rewarding in its own right.
Robert Rogers, PhD, at Oxford University, also used the prisoner's dilemma in his work, in which he altered serotonin levels and evaluated the effect of this alteration on participants' behavior. Rogers also will be speaking at the minisymposium.
In the prisoner's dilemma game, people make choices that affect each other, either favoring one person as a result of unequal sharing, or expressing more cooperative decision-making.
Working with subjects in pairs, Rogers blocked levels of l-tryptophan-the precursor of serotonin-in some participants. This had the effect of temporarily decreasing serotonin levels in these subjects.
As a result, Rogers found, the game participants became less willing to cooperate with each other. Lower serotonin levels also had the effect of changing the subjects' judgment of the social characteristics of others.
Rogers suggests that lower serotonin levels "diminished the reward value of cooperative behavior." Serotonin may also "play a role in modulating the cognitions that underpin dependable relationships with our social partners," he says.
Such findings also may indicate a role for prisoner's dilemma and other models based on game theory in enhancing understanding of and developing therapies for psychiatric disorders.
Adapted from materials provided by Society For Neuroscience.

Fausto Intilla
www.oloscience.com