Posts tagged behavior
Posts tagged behavior
Early treatment sparks striking brain changes in autism
When given early treatment, children with autism spectrum disorders (ASD) made significant improvements in behavior, communication, and most strikingly, brain function, Yale School of Medicine researchers report in a new study.
The study was published in the current issue of the Journal of Autism and Developmental Disorders by Yale Child Study Center researchers Dr. Fred Volkmar, Kevin A. Pelphrey, and their colleagues.
The results suggest that brain systems supporting social perception respond well to an early intervention behavioral program called pivotal response treatment. This treatment includes parent training, and employs play in its methods.
New findings led by Dr. Michael Lombardo, Prof. Simon Baron-Cohen and colleagues at the University of Cambridge indicate that testosterone levels early in fetal development influence later sensitivity of brain regions related to reward processing and affect an individual’s susceptibility to engage in behavior, that in extremes, are related to several neuropsychiatric conditions that asymmetrically affect one sex more than the other.
Although present at low levels in females, testosterone is one of the primary sex hormones that exerts substantial influence over the emergence of differences between males and females. In adults and adolescents, heightened testosterone has been shown to reduce fear, lower sensitivity to punishment, increase risk-tasking, and enhance attention to threat. These effects interact substantially with context to affect social behavior.
This knowledge about the effects of testosterone in adolescence and adulthood suggests that it is related to influencing the balance between approach and avoidance behavior. These same behaviors are heightened in the teenage years and also emerge in extremes in many neuropsychiatric conditions, including conduct disorder, depression, substance abuse, autism, and psychopathy.
Scientists have long known that sex differences influence many aspects of psychiatric disorders, including age of disease onset, prevalence, and susceptibility. For example, according to the World Health Organization, depression is twice as common in women than men, whereas alcohol dependence shows the reverse pattern. In addition to many other factors, sex hormone levels are likely to be important factors contributing to sex differences in psychopathology.
However, research to date has mainly focused on sex hormone levels during adolescence and adulthood, when hormone levels are heightened and built upon substantial prior developmental experience. Sex hormone levels are also heightened during critical periods of fetal brain development, but the impact of such prenatal surges in sex hormone levels on subsequent adult brain and behavioral development has received relatively little attention.
“This study is the first to directly examine whether testosterone in fetal development predicts tendencies later in life to engage in approach-related behavior (e.g., fun-seeking, impulsivity, reward responsivity) and also how it may influence later brain development that is relevant to such behaviors,” said first author Lombardo.
In this study, they tested a unique cohort of boys, 8-11 years of age, whose fetal testosterone had been previously measured from amniotic fluid at 13-20 weeks gestation. The boys were scanned with functional magnetic resonance imaging technology to assess changes in brain activity while viewing pictures of negative (fear), positive (happy), neutral, or scrambled faces.
They found that increased fetal testosterone predicted more sensitivity in the brain’s reward system to positively, compared to negatively, valenced facial cues. This means that reward-related brain regions of boys with higher fetal testosterone levels respond more to positive facial emotion compared to negative facial emotion than boys who with smaller levels of fetal testosterone.
In addition, increased fetal testosterone levels predicted increased behavioral approach tendencies later in life via its influence on the brain’s reward system. Lombardo explained, “This work highlights how testosterone in fetal development acts as a programming mechanism for shaping sensitivity of the brain’s reward system later in life and for predicting later tendency to engage in approach-related behaviors. These insights may be especially relevant to a number of neuropsychiatric conditions with skewed sex ratios and which affect approach-related behavior and the brain’s reward system.”
Dr. John Krystal, Editor of Biological Psychiatry, commented, “These remarkable data provide new evidence that hormonal exposures early in life can have lasting impact on brain function and behavior.”
Smoking and hyperactivity (ADHD) share common genetic risk factor
A variation of a particular gene may link the behaviours typical of childhood attention hyperactivity disorder, or ADHD for short, and those associated with smoking, suggests research published online in the Archives of Disease in Childhood (1, 2)
Childhood ADHD and subsequent smoking in adulthood frequently go hand in hand, say the authors, with people who have been diagnosed with ADHD more likely to start smoking early and to smoke twice as much as those without the condition.
The researchers focused on five variations in DNA sequences (single nucleotide polymorphisms or SNPs) in different genes that are strongly associated with different aspects of smoking behaviour, such as the number of cigarettes smoked every day, and taking up and quitting smoking.
How the brain controls our habits
Habits are behaviors wired so deeply in our brains that we perform them automatically. This allows you to follow the same route to work every day without thinking about it, liberating your brain to ponder other things, such as what to make for dinner.
However, the brain’s executive command center does not completely relinquish control of habitual behavior. A new study from MIT neuroscientists has found that a small region of the brain’s prefrontal cortex, where most thought and planning occurs, is responsible for moment-by-moment control of which habits are switched on at a given time.
“We’ve always thought — and I still do — that the value of a habit is you don’t have to think about it. It frees up your brain to do other things,” says Institute Professor Ann Graybiel, a member of the McGovern Institute for Brain Research at MIT. “However, it doesn’t free up all of it. There’s some piece of your cortex that’s still devoted to that control.”
The new study offers hope for those trying to kick bad habits, says Graybiel, senior author of the new study, which appears this week in the Proceedings of the National Academy of Sciences. It shows that though habits may be deeply ingrained, the brain’s planning centers can shut them off. It also raises the possibility of intervening in that brain region to treat people who suffer from disorders involving overly habitual behavior, such as obsessive-compulsive disorder.
Will Neuroscience Radically Transform the Legal System?
Although academic fields will often enjoy more than Andy Warhol’s famous 15 minutes of fame, they too are subject to today’s ever-hungry machinery of hype. Like people, bands, diets, and everything else, a field gets discovered, plucked from obscurity, thrown into the spotlight, and quickly replaced as it becomes yesterday’s news.
Neuroscience is now the popular plat de jour, or, perhaps better, the prefixde jour, and neurolaw is one of the main beneficiaries—and victims. Neuroscience will have important and even dramatic effects on our society and, as a result, on our laws. But not yet, and not as dramatically as some envision.
First, consider timing. Many of the most interesting neuroscience results come from functional magnetic resonance imaging (fMRI). This technique allows us to see what parts of the brain are working and when, and thus to begin to correlate subjective mental states with physical brain states. The use of fMRI on humans goes back about 15 years, and although about 5,000 peer-reviewed scientific articles involving fMRI will be published this year, we are still trying to figure out how it works—or doesn’t. The fMRI results showing apparently purposeful brain activity in dead salmon are a wonderfully funny example of some of the limits of this technology, and fMRI is one of the oldest of the “new” neuroscience technologies. Half of what neuroscience is teaching us about human brain function will be shown, in the next 20 years, to be wrong—and we will need each of those 20 years to figure out which half.
But, second, we need a sense of proportion. Neuroscience will provide tools that will change the law in some important ways, but those tools will be neither perfect nor used in isolation, and those changes are not likely to strike at the law’s roots.
New research reveals more about how the brain processes facial expressions and emotions
Facial mimicry—a social behavior in which the observer automatically activates the same facial muscles as the person she is imitating—plays a role in learning, understanding, and rapport. Mimicry can activate muscles that control both smiles and frowns, and evoke their corresponding emotions, positive and negative. The studies reveal new roles of facial mimicry and some of its underlying brain circuitry.
New findings show that:
- Special brains cells dubbed “eye cells” activate in the amygdala of a monkey looking into the eyes of another monkey, even as the monkey mimics the expressions of its counterpart (Katalin Gothard, MD, PhD, abstract 402.02).
- Social status and self-perceptions of power affect facial mimicry, such that powerful individuals suppress their smile mimicry towards other high-status people, while powerless individuals mimic everyone’s smile (Evan Carr, BS, abstract 402.11).
- Brain imaging studies in monkeys have revealed the specific roles of different regions of the brain in understanding facial identity and emotional expression, including one brain region previously identified for its role in vocal processing (Shih-pi Ku, PhD, abstract 263.22).
- Subconscious facial mimicry plays a strong role in interpreting the meaning of ambiguous smiles (Sebastian Korb, PhD, abstract 402.23).
Another recent finding discussed shows that:
- Early difficulties in interactions between parents and infants with cleft lip appear to have a neurological basis, as change in a baby’s facial structure can disrupt the way adult brains react to a child (Christine Parsons, PhD).
(Image Credit: iStockphoto/Joan Vicent Cantó Roig)
Could Stem Cells Treat Autism? Newly Approved Study May Tell
Autism researchers have been given the go-ahead by the U.S. Food and Drug Administration to launch a small study in children with autism that evaluates whether a child’s own umbilical cord blood may be an effective treatment.
Thirty children with the disorder, aged 2 to 7, will receive injections of their own stem cells from umbilical cord blood banked by their parents after their births. All of the cord blood comes from the Cord Blood Registry, the world’s largest stem cell bank.
Scientists at Sutter Neuroscience Institute, in Sacramento, Calif., said the placebo-controlled study will evaluate whether the stem cell therapy helps improve language and behavior in the youngsters.
There is anecdotal evidence that stem cell infusions may have a benefit in other conditions such as cerebral palsy, said lead study investigator Dr. Michael Chez, director of pediatric neurology at the institute.
“We’re hoping we’ll see in the autism population a group of patients that also responds,” Chez said. Other autism and stem cell research is going on abroad, but this study is the first to use a child’s own cord blood stem cells.
Chez said the study will involve only patients whose autism is not linked to a genetic syndrome or brain injury, and all of the children will eventually receive the stem cells.
Babies Learn the Smell of Mum
Researchers show for the first time that a mammal begins to suckle its mother’s milk through a learned response built on learning her unique combination of smells. When it is born, the newborn is exposed to the smell of its mother’s amniotic fluid and the baby then responds to those smells to feed.
Prevailing thought has been that pheromones –chemicals that trigger an innate behavior – drove the suckling response as an automatic behavior. The new work determines that, in mice, the smells must be learned before the behavior can occur.
Suckling is a critical step for survival in mammals, which are defined by giving birth to offspring that need to feed from their mother’s milk. The newborn must begin to feed soon after birth or it will die. It is a crucial, defining behavior in mammals and offers researchers an opportunity to investigate the biology of instinct.
Using the new science of optogenetics, scientists can activate or shut down neural pathways, altering behavior and heralding a true cure for psychiatric disease.
Stopped at a red light on his drive home from work,contemplates one of his patients, a woman with depression so entrenched that she had been unresponsive to drugs and electroshock therapy for years. The red turns to green and Deisseroth accelerates, navigating roads and intersections with one part of his mind while another part considers a very different set of pathways that also can be regulated by a system of lights. In his lab at Stanford University’s Clark Center, Deisseroth is developing a remarkable way to switch brain cells off and on by exposing them to targeted green, yellow, or blue flashes. With that ability, he is learning how to regulate the flow of information in the brain.
Deisseroth’s technique, known broadly as, could bring new hope to his most desperate patients. In a series of provocative experiments, he has already cured the symptoms of psychiatric disease in mice. Optogenetics also shows promise for defeating drug addiction. When Deisseroth exposed a set of test mice to cocaine and then flipped a switch, pulsing bright yellow light into their brains, the expected rush of euphoria—the prelude to addiction—was instantly blocked. Almost miraculously, they were immune to the cocaine high; the mice left the drug den as uninterested as if they had never been exposed.
Using precisely-targeted lasers, researchers manipulate neurons in worms’ brains and take control of their behavior
In the quest to understand how the brain turns sensory input into behavior, Harvard scientists have crossed a major threshold. Using precisely-targeted lasers, researchers have been able to take over an animal’s brain, instruct it to turn in any direction they choose, and even to implant false sensory information, fooling the animal into thinking food was nearby.
As described in a September 23 paper published in Nature, a team made up of Sharad Ramanathan, an Assistant Professor of Molecular and Cellular Biology, and of Applied Physics, Askin Kocabas, a Post-Doctoral Fellow in Molecular and Cellular Biology, Ching-Han Shen, a Research Assistant in Molecular and Cellular Biology, and Zengcai V. Guo, from the Howard Hughes Medical Institute were able to take control of Caenorhabditis elegans – tiny, transparent worms – by manipulating neurons in the worms’ “brain.”
(Image credit: Ian D. Chin-Sang)