|
The Brain
Written and researched by Bob Murray, PhD
Latest News |
Back Issues | Get updates:
Subscribe Now
Lost in Thought
Sep 17, 2006
Prof. Rafael Malach, Ilan Golberg and Michal Harel of the Weizmann Institute's Neurobiology Department found a scientific means of addressing this question--by scanning the brains of volunteers performing various mental tasks. The results of their study, which were published recently in the journal Neuron, were unanticipated: When subjects were given outwardly-focused tasks that demanded their full attention, areas of the brain that relate to the self were not only inactive--they appeared to be vigorously suppressed.
The functional brain scans were done with an MRI (Magnetic Resonance Imaging) system, which maps brain activity by measuring changes in blood flow and oxygenation. Volunteers either viewed photos or listened to short music segments. For each stimulus, however, participants were asked to perform two different tasks. In one, "introspective" assignment, they were asked to think about themselves and how the image or musical selection made them feel. In the second, "sensory-motor" task, they performed quick recognition exercises--such as identifying pieces that included a trumpet's sound. The scientists were particularly interested in certain regions in the prefrontal cortex, a part of the brain known to be involved in personality and self-knowledge, among other things. Indeed, the fMRI confirmed that these regions were active during introspection but, when subjects were absorbed in the recognition task, activity in these areas was silenced. (fMRI readings in these areas fell below those measured when subjects were resting.)
"It is tempting," says Malach, "to put these findings in a broader perspective, one that veers away from traditional western thought, with its emphasis on self-control and for which 'someone is always minding the store,' and toward more eastern perspectives, in which the 'self must be abandoned in order to fully engage with the outside world.'" On a more scientific level, their study suggests that the brain's self-awareness centers do not function as a critical element that allows perceptual awareness of the outside world. Rather, the self-related areas of the prefrontal cortex appear to be engaged specifically when we are aware both of the sensory experience and of ourselves as the observers of this experience. When we are so occupied with the outside world as to "forget ourselves," only local, sensory-specific systems seem to be needed.
Read more in Neuron
Top of page
Liars Have Different Brains
May 25, 2006
Looking into the brains of people who habitually cheat and lie, neuroscientists have found abnormalities in the area that controls higher thinking. Pathological liars have less gray matter and more white matter in their prefrontal cortex, according to a report in the October issue of The British Journal of Psychiatry.
Gray matter consists of the cells that do the thinking, while white matter consists of the cells that connect them.
According to the report's co-author Adrian Raine, a professor of psychology at the University of Southern California in Los Angeles the more networking there is in the prefrontal cortex, the more the person has an upper hand in lying. Raine was quoted in the NY Times as explaining: "Their verbal skills are higher. They almost have a natural advantage."
Is that how certain politicians got to be where they are, we wonder?
According to the researchers liars have 22 percent more white matter than normal people and 14.2-percent less gray matter. That means that liars have more tools to lie and fewer moral restraints than normal people, Raine says, since experts believe that this gray matter is also what controls moral behavior. "The reduction in gray matter predisposes them to lie in the first place," he says. The researchers' findings could eventually be used in making diagnoses of behavioral problems and might have applications in the criminal-justice system. And, of course, in politics!
Read more in the British Journal of Psychiatry
Top of page
Don't Try To Change My Mind With Facts!
May 25, 2006
When it comes to forming opinions and making judgments on hot political issues, partisans of both major US parties don't let facts get in the way of their decision-making, according to an Emory University study.
The research sheds light on why staunch Democrats and Republicans can hear the same information, but walk away with opposite conclusions.
The investigators used functional neuroimaging (fMRI) to study a sample of committed Democrats and Republicans during the three months prior to the U.S. Presidential election of 2004. The Democrats and Republicans were given a reasoning task in which they had to evaluate threatening information about their own candidate. During the task, the subjects underwent fMRI to see what parts of their brain were active.
What the researchers found was striking. "We did not see any increased activation of the parts of the brain normally engaged during reasoning," says Drew Westen, director of clinical psychology at Emory University who led the study. "What we saw instead was a network of emotion circuits lighting up, including circuits hypothesized to be involved in regulating emotion, and circuits known to be involved in resolving conflicts." Westen and his colleagues presented their findings at the Annual Conference of the Society for Personality and Social Psychology on Jan, 28.
Once partisans had come to completely biased conclusions -- essentially finding ways to ignore information that could not be rationally discounted -- not only did circuits that mediate negative emotions like sadness and disgust turn off, but subjects got a blast of activation in circuits involved in reward -- similar to what addicts receive when they get their fix, Westen explains.
"None of the circuits involved in conscious reasoning were particularly engaged," says Westen. "Essentially, it appears as if partisans twirl the cognitive kaleidoscope until they get the conclusions they want, and then they get massively reinforced for it, with the elimination of negative emotional states and activation of positive ones."
During the study, the partisans were given 18 sets of stimuli, six each regarding President George W. Bush, his challenger, Senator John Kerry, and politically neutral male control figures such as actor Tom Hanks. For each set of stimuli, partisans first read a statement from the target (Bush or Kerry).
The first statement was followed by a second statement that documented a clear contradiction between the target's words and deeds, generally suggesting that the candidate was dishonest or pandering. Next, partisans were asked to consider the discrepancy, and then to rate the extent to which the person's words and deeds were contradictory. Finally, they were presented with an exculpatory statement that might explain away the apparent contradiction, and asked to reconsider and again rate the extent to which the target's words and deeds were contradictory.
Behavioral data showed a pattern of emotionally biased reasoning: partisans denied obvious contradictions for their own candidate that they had no difficulty detecting in the opposing candidate. Importantly, in both their behavioral and neural responses, Republicans and Democrats did not differ in the way they responded to contradictions for the neutral control targets, such as Hanks, but Democrats responded to Kerry as Republicans responded to Bush.
While reasoning about apparent contradictions for their own candidate, partisans showed activations throughout the orbital frontal cortex, indicating emotional processing and presumably emotion regulation strategies. There also were activations in areas of the brain associated with the experience of unpleasant emotions, the processing of emotion and conflict, and judgments of forgiveness and moral accountability.
Notably absent were any increases in activation of the dorsolateral prefrontal cortex, the part of the brain most associated with reasoning (as well as conscious efforts to suppress emotion). The finding suggests that the emotion-driven processes that lead to biased judgments likely occur outside of awareness, and are distinct from normal reasoning processes when emotion is not so heavily engaged, says Westen.
The investigators hypothesize that emotionally biased reasoning leads to the 'stamping in' or reinforcement of a defensive belief, associating the participant's 'revisionist' account of the data with positive emotion or relief and elimination of distress. "The result is that partisan beliefs are calcified, and the person can learn very little from new data," Westen says.
The study has potentially wide implications, from politics to business, and demonstrates that emotional bias can play a strong role in decision-making, Westen says. "Everyone from executives and judges to scientists and politicians may reason to emotionally biased judgments when they have a vested interest in how to interpret 'the facts,'" Westen says.
This story is not available on the web.
Top of page
Alzheimers Hits The Educated Faster
May 25, 2006
It has long been known that the incidence of Alzheimers' disease was in some way related to educational level. Most researchers had come to the conclusion that a higher degree somehow conferred some degree of immunity from the disease. Not so according to a report in the Journal of Neurology, Neurosurgery and Psychiatry.
The new findings are based on a study of 312 patients living in New York who were diagnosed with Alzheimer's disease and followed for an average of 5.6 years. Up to nine neuropsychological tests were performed on each subject during the course of the study.
Overall, mental agility fell by nine per cent of a standard deviation each year, according to lead author Dr Nikolaos Scarmeas and colleagues from Columbia University Medical Centre in New York. For each year of added education, the decline increased by 0.3 per cent. Memory and executive speed, which includes the ability to adapt to change and organise thoughts, were the primary areas affected by educational level, the report indicates.
In other words the more highly educated you are the faster the progression of the disease!
Further analysis showed the link between education and mental decline was not influenced by age, mental function at the time of diagnosis, or other factors known to influence brain function, such as depression and vascular disease.
Previous studies have provided evidence high levels of education can delay Alzheimer's disease. The "cognitive reserve" hypothesis has been put forth to explain the effects of education on Alzheimer's disease, Dr Scarmeas and colleagues said. This theory, they explain, holds that highly educated individuals have more intellectual reserve so the onset of overt Alzheimer's disease symptoms is delayed.
However, once symptoms become apparent, more damage has accumulated than in less educated brains, so the subsequent decline in mental function is more rapid.
My own suspicion, based on a number of studies, is that community involvement, the strength of relationships, the desire to learn new things, a connection to nature, the level of active spirituality and genetics all play an intricate dance giving immunity or otherwise to the disease. It may be that educated people, especially academics, have a stronger sense of community and that when that goes on retirement the decline is more rapid.
Read more in the Journal of Neurology, Neurosurgery and Psychiatry
Top of page
Love is in the Brain
Aug 5, 2005
Have all those songs got it wrong? And all those psychologists from Freud to the present? Is it a love drive not a sex drive after all?
A team led by a neuroscientist, an anthropologist and a social psychologist found love-related neurophysiological systems (drives to you and me) inside a magnetic resonance imaging machine.
They detected quantifiable love responses in the brains of 17 young men and women who each described themselves as being newly and madly in love.
The multidisciplinary team found that early, intense romantic love may have more to do with motivation, reward and "drive" aspects of human behavior than with the emotions or sex drive. Brain systems were activated that humans share with other mammals. So the researchers think "early-stage romantic love is possibly a developed form of a mammalian drive to pursue preferred mates, and that it has an important influence on social behaviors that have reproductive and genetic consequences."
"It's a stark reminder that the mind truly is in the brain," noted Lucy L. Brown of the Albert Einstein College of Medicine. "We humans are built to experience magical feelings like love, but our findings don't diminish the magic in any way. In fact, for some, it enhances the experience. Our research also helps to explain why a person in love feels 'driven' to win their beloved, amidst a whole constellation of other feelings."
The study, entitled "Reward, motivation and emotion systems associated with early-stage intense romantic love," is published in the July issue of the Journal of Neurophysiology, published by the American Physiological Society.
"Most of the participants in our study clearly showed emotional responses," noted Arthur Aron of the State University of New York-Stony Brook, "but we found no consistent emotional pattern. Instead, all of our subjects showed activity in reward and motivation regions. To emotion researchers like me, this is pretty exciting because it's the first physiological data to confirm a connection between romantic love and motivation networks in the brain.
"As it turns out, romantic love is probably best characterized as a motivation or goal-oriented state that leads to various specific emotions, such as euphoria or anxiety," Aron noted. "With this view, it becomes clearer why the lover expresses such an imperative to pursue his or her beloved and protect the relationship." Aron added: "Our participants who measured very high on a self report questionnaire of romantic love also showed strong activity in a particular brain region."
Aron also noted that the research answered the "historic question of whether love and sex are the same, or different, or whether romantic passion is just warmed over sexual arousal." He said, "Our findings show that the brain areas activated when someone looks at a photo of their beloved only partially overlap with the brain regions associated with sexual arousal. Sex and romantic love involve quite different brain systems."
Aron reported that, using functional magnetic resonance imaging (fMRI) and other measurements, he and his colleagues found support for their two major predictions: (1) early stage, intense romantic love is associated with subcortical reward regions rich with dopamine; and (2) romantic love engages brain systems associated with motivation to acquire a reward.
Brown explains some of these findings, commenting that "when our participants looked at a photo of his/her beloved, specific activation occurred in the right ventral tegmental area (VTA) and dorsal caudate body. These regions were significant compared to two control conditions, providing strong evidence that these brain areas, which are associated with the motivation to win rewards, are central to the experience of being in love."
Another important discovery, Brown said, was that "to our surprise, the activation regions associated with intense romantic love were mostly on the right side of the brain, while the activation regions associated with facial attractiveness were mostly on the left.
"We didn't predict such a striking lateralization," Brown reported. "It is well known that speech is largely a left-sided cortical function. But our data indicate that lateralization also occurs in lower parts of the brain. Moreover, different kinds of rewards (in this case, the "rush" of romantic love, compared with the pleasing experience of looking at a pretty or handsome face) is also lateralized. These results give us a lot to think about how the normal human brain learns and remembers and functions in general," Brown added.
Another breakthrough, Brown noted, was that "we found several brain areas where the strength of neural activity changed with the length of the romance. Everyone knows that relationships are dynamic over time, but we are beginning to track what happens in the brain as a love relationship matures."
Helen E. Fisher, a research anthropologist at Rutgers University, New Jersey, noted that not only did the brain change as romantic love endured, but that some of these changes were in regions associated with pair-bonding in prairie voles. The fMRI images showed more activity in the ventral pallidum portion of the basal ganglia in people with longer romantic relationships. It's in this region
where receptors for the hormone vasopressin are critical for vole pair-bonding, or attachment.
So that's why Alicia and I are together, and in love, after 22 years! Who'd have thunk it!
"Humans have evolved three distinct but interrelated brain systems for mating and reproduction - the sex drive, romantic love, and attachment to a long term partner," Fisher said, "and our results suggest how feelings of romantic love might change into feelings of attachment. Our results support what people have always assumed--that romantic love is one of the most powerful of all human experiences. It is definitely more powerful than the sex drive."
Read more in the Journal of Neurophysiology
Top of page
Scientists Amazed At the Power of a Single Cell
Aug 5, 2005
World travelers instantly identify the architectural sails of the Sydney Opera House from most any angle. Movie aficionados immediately recognize Oscar-winner Halle Berry beneath her "Catwoman" costume or in an artist's caricature.
But how does the human brain translate varied and even abstract visual images into a single instantly and consistently recognizable concept? A research team led by neuroscientists at UCLA and California Institute of Technology shows the process begins with a single brain cell.
Reporting in the June 23 edition of journal Nature, the researchers find that individual neurons are able to recognize people, landmarks and objects--even letter, strings of names. The findings suggest a consistent, sparse and explicit code that may play a role in transforming complex visual representations into long-term and more abstract memories.
"This new understanding of individual neurons as 'thinking cells' is an important step toward cracking the brain's cognition code," said senior investigator Dr. Itzhak Fried, professor of neurosurgery at the David Geffen School of Medicine at UCLA "As our understanding grows, we one day may be able to build cognitive prostheses (like artificial limbs) to replace functions lost due to brain injury or disease, perhaps even for memory."
"Our findings fly in the face of conventional thinking about how brain cells function," adds senior investigator Christof C. Koch, professor of Cognitive and Behavioral Biology at Caltech. "Conventional wisdom views individual brain cells as simple switches or relays. In fact, we are finding that neurons are able to function more like a sophisticated computer." This study is the latest of several landmark observations made in recent years by the UCLA team, which is probing the underpinnings of the human mind at the single neuron level in humans. Two years ago they identified single cells in the human hippocampus specific to places during human navigation.
The body of work is an example of the power of neurobiological research using data drawn directly from inside a living human brain. Most neurobiological research involves animals, post-mortem tissue or imaging. In contrast, Fried and his UCLA team draw data directly from the brains of living people.
For the latest study, the research team recorded responses from the medial temporal lobe, which plays a major role in human memory and is one of the first region's affected in patients with Alzheimer's Disease. Responses by individual neurons appeared on a computer screen as spikes on a graph.
In the initial recording session, subjects viewed a large number of images of famous people, landmark buildings, animals, objects and additional images chosen after an interview. To keep the subjects focused, researchers asked them to push a computer key to indicate whether the image was a person. After determining which images prompted a significant or strong response in at least one neuron, additional sessions tested response to three to eight variations of each of those images.
Responses among the eight subjects varied with the person and stimulus. For example, a single neuron in the left posterior hippocampus of one subject responded to 30 out of 87 images, firing in response to all pictures of actress Jennifer Aniston, but not, or only very weakly, to other famous and non-famous faces, landmarks, animals or objects. The neuron also did not respond to
pictures of Jennifer Aniston together with actor Brad Pitt.
In another instance, pictures of actress Halle Berry activated a neuron in the right anterior hippocampus of a different patient, as did a caricature of the actress, images of her in the lead role of the film "Catwoman," and a letter sequence spelling her name.
In a third subject, a neural unit in the left anterior hippocampus responded to pictures of the landmark Sydney Opera House and Baha'i Temple, and also to the letter string "Sydney Opera," but not to other letter strings, such as "Eiffel Tower."
Read more in Nature
Top of page
Brainy Birds
Aug 5, 2005
A Brandeis University researcher has shown that an African grey parrot with a walnut-sized brain understands a numerical concept akin to zero--an abstract notion that humans don't typically understand until age three or four, and that can significantly challenge learning-disabled children.
Strikingly, Alex, the 28-year-old parrot who lives in a Brandeis lab run by comparative psychologist and cognitive scientist Dr. Irene Pepperberg, spontaneously and correctly used the label "none" during a testing session of his counting skills to describe an absence of a numerical quantity on a tray. This discovery prompted a series of trials in which Alex consistently demonstrated the ability to identify zero quantity by saying the label "none."
Dr. Pepperberg's research findings, published in the current issue of The Journal of Comparative Psychology, add to a growing body of scientific evidence that the avian brain, though physically and organizationally somewhat different from the mammalian cortex, is capable of higher cognitive processing than previously thought. Chimpanzees and possibly squirrel monkeys show some
understanding of the concept of zero, but Alex is the first bird to demonstrate an understanding of the absence of a numerical set, Dr. Pepperberg noted.
"It is doubtful that Alex's achievement, or those of some other animals such as chimps, can be completely trained; rather, it seems likely that these skills are based on simpler cognitive abilities they need for survival, such as recognition of more versus less," explained Dr. Pepperberg.
Alex had previously used the label "none" to describe an absence of similarity or difference between two objects, but he had never been taught the concept of zero quantity. "Alex has a zero-like concept; it's not identical to ours but he repeatedly showed us that he understands an absence of quantity," said Dr. Pepperberg.
Historically, the use of "zero" to label a null set has not always been obvious even in human cultures, which in many cases lacked a formal term for zero as recently as the late Middle Ages. The value of number research lies mainly in its ability to help determine the extent of animal cognition and animals' potential for more complex capacities. To that end, Dr. Pepperberg's studies on the avian brain are continuing with research into Alex's ability to count, as well as add and subtract small quantities.
Yet significantly, Dr. Pepperberg's research, which uses a training method called the model-rival technique, also holds promise for teaching autistic and other learning-disabled children who have difficulty learning language, numerical concepts and even empathy.
The model rival technique involves two trainers, one to give instructions, and one to model correct and incorrect responses and to act as the student's rival for the trainer's attention; the model and trainer also exchange roles so that the student sees that the process is fully interactive. The student, in this case, a middle-aged parrot, tries to reproduce the correct behavior. So far, results using this learning technique with small groups of autistic children, taught by Diane Sherman, PhD, in Monterey, CA, have been very promising, said Dr. Pepperberg.
"This kind of research is changing the way we think about birds and intelligence, but it also helps us break down barriers to learning in humans--and the importance of such strides cannot be underestimated," said Dr. Pepperberg.
Read more in the Journal of Comparative Psychology
Top of page
Exercise Slows Onset of Alzheimer's
June 6, 2005
Recently exercise has been proven to be better than antidepressants for depression and better than Ritalin for ADD/ADHD. Now it would seem that exercise has the same beneficial effect on those suffering from Alzheimer's Disease.
Researchers have found that physical activity appears to inhibit Alzheimer's-like brain changes in mice, slowing the development of a key feature of the disease. Their research demonstrated that long-term physical activity enhanced the learning ability of mice and decreased the level of plaque-forming beta-amyloid protein fragments--a hallmark characteristic of Alzheimer's disease (AD)--in
their brains.
A number of population-based studies suggest that lifestyle interventions may help to slow the onset and progression of AD. Because of these studies, scientists are seeking to find out if and how physical or mental activity might delay the onset and progression of the disease. In this study, scientists have now shown in an animal model system that one simple behavioral intervention--exercise--could delay, or even prevent, development of AD-like syptoms by decreasing beta-amyloid levels.
Results of this study, conducted by Paul A Adlard, PhD, Carl W Cotman, PhD, and colleagues at the University of California, Irvine, are published in the April 27, 2005, issue of The Journal of Neuroscience.
To directly test the possibility that exercise (in the form of voluntary running) may reduce the cognitive decline and brain changes that characterize AD, the study used genetically engineered animals rather than normal mice. These mice begin to develop AD-like amyloid plaques at around 3 months of age. Initially, young mice (6 weeks or 1 month of age) were placed in cages with or without running wheels for periods of either 1 month or 5 months, respectively.
Mice with access to running wheels had the opportunity to exercise any time, while those without the wheels were classified as "sedentary." On 6 consecutive days after the exercise phase, the researchers placed each mouse in a Morris water maze to examine how fast it could learn the location of a hidden platform and how long it retained this information. (This water maze task involves a small pool of water with a submerged platform that the mouse must learn how to find.)
The animals that exercised learned the task faster. Thus, the mice that used the running wheels for 5 months took less time than the sedentary animals to find the escape platform. The exercised mice acquired maximal performance after only 2 days on the task, while it took more than 4 days for the sedentary mice to reach that same level of performance. This suggests that exercise may help to offset learning/cognitive deficits present in AD patients.
Next, the investigators examined tissues from the brains of mice that had exercised for 5 months. Compared to the sedentary animals, mice that had exercised for 5 months on the running wheels had significantly (50%) fewer plaques and fewer beta-amyloid fragments (peptides) in the cerebral cortex and hippocampus, that characterize AD. Additional studies, of exercised animals at 10 weeks old, showed that the mechanism underlying this difference began within the first month of exercise.
"These results suggest that exercise--a simple behavioral strategy--in these mice may bring about a change in the way that amyloid precursor protein is metabolized," says D. Stephen Snyder, Ph.D., director of the etiology of Alzheimer's program in the NIA's Neuroscience and Neuropsychology of Aging Program. "From other research, it is known that in the aging human brain, deposits of beta-amyloid normally increase. This study tells us that development of those deposits can be reduced and possibly eliminated through exercise"
Mental exercise also helps!
These findings follow another recent report of a link between an enriched environment and Alzheimer's-like brain changes. That study, published by Orly Lazarov, PhD, and colleagues in the March 11, 2005, issue of the journal Cell, found that beta-amyloid levels decreased in the brains of another kind of genetically modified mice when they were housed in groups and in environments that were enriched with running wheels, colored tunnels, and toys.
"Both of these studies are exciting because they offer insight into one of the pathways through which exercise and environment might promote resistance to development of cognitive changes that come with aging and AD," Snyder notes.
Read more in the Journal of Neuroscience
Read more in Cell
Top of page
How Babies Learn Language
April 1, 2005
Adults may feel silly when they talk to babies, but those babies will learn to speak sooner if adults talk to them like infants instead of like other adults, according to a study by Carnegie Mellon University Psychology Professor Erik Thiessen published in the March 2005 issue of the journal Infancy.
Most adults speak to infants using so-called infant-directed speech: short, simple sentences coupled with higher pitch and exaggerated intonation. Researchers have long known that babies prefer to be spoken to in this manner. But Thiessen's research has revealed that infant-directed speech also helps them learn words more quickly than normal adult speech.
In a series of experiments, he and his colleagues exposed 8-month-old infants to fluent speech made up of nonsense words. The researchers assessed whether, after listening to the fluent speech for less than two minutes, infants had been able to learn the words. The infants who were exposed to fluent speech with the exaggerated intonation contour characteristic of infant-directed speech learned to identify the words more quickly than infants who heard fluent speech spoken in a more monotone fashion.
Thiessen's study may also explain why many adults struggle to learn a second language even though they are able to use their own language effortlessly. Children, after all, learn to speak practically from scratch, and most experts believe infants are more adept than adults at language learning. "Learning a language is one of the most critical things that an infant has to do, because communication with other people is tremendously important," Thiessen said. "It makes a great deal of sense that the special way we have of talking to babies would help them learn."
Read more in Infancy
Top of page
Active Lifestyle Helps Prevent Alzheimer's
April 1, 2005
Researchers at the University of Chicago working with mice found that an enriched environment--in this case more chances to exercise, explore and interact with others--can dramatically reduce the biological hallmarks of Alzheimer's disease in animals genetically predisposed to the disorder.
In the journal Cell, the researchers show that mice raised in a deluxe setting--large cages filled with running wheels, colored tunnels and multiple toys--had much less of the beta-amyloid peptides that are characteristic of Alzheimer's disease deposited in their brains and far lower levels of these damaging peptides in their blood than genetically similar mice raised in a standard environment.
Mice from enriched settings also had more of an enzyme that breaks down amyloid as well as increased activity of several genes involved in learning and memory, brain cell survival and the growth of new blood vessels. "We have plenty of epidemiological evidence connecting activity, exercise and education with later onset of Alzheimer's, but it has never been clear which came first," said study-author Sangram Sisodia, PhD, professor of neurobiology, pharmacology and physiology at the University of Chicago. "Did the active lifestyle delay disease, or was there something inherent in a disease-resistant brain that led to a mentally and physically active lifestyle?"
"This is the first demonstration," he said, ""in a genetically clean, carefully controlled animal model showing that an enhanced environment can have such a tremendously beneficial impact, protecting the brain from the pathological hallmarks of this insidious disease."
These findings support a "potentially causal inverse relationship between a more engaging, enriched life and AD progression," the researchers note. They also provide "clear initial directions for exploring the role of the environment and the molecular pathways perturbed in AD and other neurodegenerative disorders."
Sisodia, and colleagues studied mice carrying two distinct genes (amyloid precursor protein and presenilin-1) that predispose the animals to develop Alzheimer's early in life. At one month of age, nine of these mice were placed in the enriched environment and seven in standard housing. After five months, the researchers began to search for the pathological signs of AD in the mice's brains.
They found that mice from the enriched environment had a dramatic reduction of amyloid deposits in their brains, including less than half the volume of amyloid deposits in the hippocampus and cortex, regions involved in memory and reasoning.
The researchers also looked for genes that were activated at different levels in brains of mice from enriched versus standard housing. They identified 41 such genes, many of them already known to protect nerve cells. One of them was the gene for an enzyme that degrades beta-amyloid called neprilysin, which was at significantly higher levels in mice from the enhanced setting.
The researchers also noted one "personality" difference among the mice in the enriched environment that influenced amyloid levels. Some of these mice were extremely active, frequently exploring their cages or running on the wheel. Others, the couch-potato mice, had the same opportunities for exercise but chose much less activity.
The most active mice had the least beta-amyloid. Less active mice from the enriched environment had more and those from the standard housing, who got the least exercise, had the most.
A lot of the process involves simple plumbing, Sisodia suspects, delivering blood to the brain and carrying harmful substances away. "It may be all about blood flow," he suggested. Exercise and mental activity can stimulate growth of new vessels while they help keep existing vessels in the brain open and functional, just like in the heart.
The take home message for humans, he said, is use it or lose it. ""Activity helps, physical activity helps and mental activity helps," he said, "and the earlier you begin the better, a troubling notion in an increasingly inactive society. This is prevention, not therapy."
About 4.5 million people in the United States have Alzheimer's disease, including about five percent of those aged 65 to 74. Risk increases with age.
Read more in Cell.
Top of page
Ageing Improves Vision
March 1, 2005
It's not all down hill from here, folks! The long-held belief that older people perform slower and worse than younger people has been proven wrong. In a study published in Neuron, psychologists from McMaster University discovered that the ageing process actually improves certain abilities: Older people appear to be better and faster at grasping the big picture than their younger counterparts. That's, after all, what the tribal council of elders was supposed to do. They knew a thing or two those hunter-gatherers!
"Going into the study, we knew that ageing changes the way people see the world," says Allison Sekuler, one of the senior authors. "But these results are an unusual twist on the standard 'ageing makes you worse' story, and they provide clear insight into what is changing in the ageing brain."
Using computer-generated stimuli, the researchers monitored how much time subjects needed to process information about the direction in which a set of bars moved. When the bars were small, or when the bars were low in contrast (light gray vs. dark gray), younger subjects took less time to see the direction of motion. But when the bars were large, and high in contrast (black vs. white), older subjects outperformed the younger subjects.
"The results are exciting not only because they show an odd case in which older people have better vision than younger people, but also because it may tell us something about how ageing affects the way signals are processed in the brain," says Patrick Bennett, the other senior author.
The results suggest that as we age, the ability of one brain cell to inhibit another is reduced. That sort of inhibition helps young people find an object hidden among clutter, but it can make it hard to tune into the clutter itself. When the young brain sees big, high-contrast bars, it effectively tunes out because there is no object hidden in the bars. But older brains do not inhibit
information in the same way, so they do not tune out the bars, and they can actually perform the task better.
"As we get older, it becomes harder to concentrate on one thing and ignore everything else," says Bennett. "It takes more effort to tune out distractions. We've seen it in cognition and speech studies, and now we see it in vision. Although we don't know if those are all linked, we think the visual effect is due to changes in the effectiveness of inhibitory neurotransmitters in the brain." Neurotransmitters (as all frequent readers of our site know by now) are chemical substances that can modify the way in which brain cells talk to one another. Some neurotransmitters enhance brain signals, and others inhibit them.
The study suggests that one type of inhibitory neurotransmitter may not have as much effect in old brains as in young brains. However, the researchers caution that although such a change makes older people perform better on this task, the same change likely leads to increased difficulties in a much wider range of tasks. "It's critical to understand how ageing affects vision and the brain. If we can characterize what is happening to our brains as we age, we'll be in a better position to help seniors see better for longer," says Sekuler.
Read more in Neuron.
Top of page
How Babies Recognize Mother
December 6, 2004
We are born with the capacity to recognize faces, new research has found. While neurobiologists have known for some time that a particular area of the brain, called the fusiform face area (FFA), lights up with activity when we see a face--and even that the FFA is necessary for us to recognize faces--there has been controversy over what kind of processing the area is doing.
Now, researchers Galit Yovel and Nancy Kanwisher have tackled two central questions with one set of experiments: the nature of processing that occurs in the FFA and whether the FFA is "domain specific," that is, exclusively involved in face perception, or whether the area is engaged in more general spatial processing of visual features.
What they found was that the FFA extracts configural information about faces (ie sees them as a whole) rather than processing spatial information on the parts of faces. This is quite different to what researchers had previously believed. Also, their studies indicated that the FFA is exclusively involved in face recognition. So we have a part of the brain whose sole job is to recognize faces. Our mug shot filing system.
The researchers' experiments used functional magnetic resonance imaging (fMRI) of subjects as they performed recognition tasks. In the fMRI, scans harmless magnetic fields and radio signals are used to measure brain activity as subjects perform tasks.
Read more in Neuron
Top of page
Use it or Lose It: Seniors Need to Socialize to Keep Communication Skills
September 1, 2004
Senior citizens living alone and independently in apartments should interact often with others--both friends and family members--if they want to maintain their ability to communicate, a new University of Michigan study showed.
A lifestyle with organized activities seems to provide the best social opportunities for the elderly, said Deborah Keller-Cohen, a U-M professor of women's studies and linguistics.
Much is known about the association between declines in cognitive function among the elderly and the ability to communicate, but little has been explored about what role social engagement might play in that relationship. The U-M research targeted people 85 and older-the fastest growing segment of the US population, Keller-Cohen said.
The researchers examined the relationships among social engagement, cognition and communicative skills. They reviewed notebooks kept by the study's participants, who tracked the frequency, purpose and quality of interactions. The participants were tested on their ability to name objects in pictures, a common measure of language skill ability.
Individuals who experienced less cognitive decline were involved in a wider range of relationships, each of which challenges individuals to speak and listen to others on a range of topics. Thus, this diversity in interaction would seem to keep one's linguistic skills activated, she said.
When the elderly limited their contact solely to family members, they didn't fare as well as they could have with communications skills had they also interacted with others, Keller-Cohen said. Although additional research is required, this might have implications for how senior living centers structure programming and activities.
"It's possible that as individuals decline cognitively, they become less able to handle social contact and become more dependent on family members who by virtue of kin obligations, will continue to interact with them," she said.
This research, "Social Contact and Communication in People Over 85," was presented at the recent American Psychological Association conference in Hawaii and has not yet been published.
Top of page
Reading, Writing, Rithmatic, Rhythm and Role-Playing: The New Five Rs?
September 1, 2004
Just when schools all over the developed world were gutting down on their "non essential" subjects such as music and drama comes a study which confirms that these subjects maybe should be right up there with the other Rs.
The study, led by Dr E Glenn Schellenberg, of the University of Toronto, examined the effect of extra-curricular activities on the intellectual and social development of six-year-old children. A group of 144 children were recruited through an ad in a local newspaper and assigned randomly to one of four activities: keyboard lessons, voice lessons, drama lessons, or no lessons.
Two types of music lessons were offered in order to be able to generalize the results, while the groups receiving drama lessons or no lessons were considered control groups in order to test the effect of music lessons over other art lessons requiring similar skill sets and nothing at all. The activities were provided for one year.
The participating children were given IQ tests before and after the lessons. The results of this study revealed that increases in IQ from pre- to post-test were larger in the music groups than in the two others. Generally these increases occurred across IQ subtests, index scores, and academic achievement. Children in the drama group also exhibited improvements pre- to post-test, but in the area of adaptive social behavior, an area that did not change among children who received music lessons.
The study was published in the August 2004 issue of Psychological Science.
Read more in Psychological Science
Top of page
What Are Babies Thinking?
August 4, 2004
Look who's thinking! A study published in the July 22 issue of Nature shows that babies are quite thoughtful, even if they don't have the words to express their thoughts.
The research was conducted by Sue Hespos, assistant professor of psychology at Vanderbilt University, and Elizabeth Spelke, professor of psychology at Harvard University. “It's been shown in previous studies that adults actually categorize things differently based on what language they speak,” Hespos said. “So, if language is influencing adults' thought, one of our questions was, what's going on with preverbal infants? Do children think before they speak?
“Language capitalizes on a pre-existing system of 'I live in a 3-D world, I know how objects behave and interact,'” she continued. “This pre-existing ability suggests that children do think before they speak.”
Previous research has found that infants are sensitive to the acoustic variations that signal meanings in all the world's languages that adults can no longer hear, even those variations that their own language does not use and that the adults around them no longer hear. For instance, an adult native-English speaker will not hear all of the sounds of Korean and vice versa. Infants hear these subtleties but lose this awareness as their language skills develop over the first year of life.
“The languages of the world vary both in the sounds they require speakers to distinguish and in the meanings they require speakers to convey, and these differences influence what speakers of a language readily hear and think about,” Spelke said. “Our research asked how these differences arise: Does the experience of learning to speak English or Korean make you aware of the categories your language honors?”
The example they used to explore this question was differences between how different languages describe space. For example, the distinction between a tight fit versus a loose fit is marked in Korean but not in English. A cap on a pen would be a tight fit relationship, while a pen on a table would be a loose fit relationship. English does not mark this distinction in the same way, instead emphasizing the “containment” versus “support” relationship, for example: the coffee is in the mug or the mug is on the table.
Hespos and Spelke tested whether five-month-old infants from native English-speaking homes noticed whether objects fit tightly or loosely. The tests were based on infants' tendency to look at events that they find to be novel. Infants were shown an object being placed inside a container that fit either tightly or loosely until the time they looked at the object being placed inside the container decreased. They were then shown new tight and loose fit relationships. The researchers found that the babies looked at the objects longer when there was a change between tight or loose fit, illustrating that they were detecting the Korean concept.
Hespos and Spelke also conducted the experiment with adults to confirm that English-speaking adults do not spontaneously make the tight versus loose fit distinction. “Adults ignore tight fit versus loose fit and pay attention to 'in' versus 'on,'” Hespos said. “Adults were glossing over the distinction that the babies were actually detecting.”
“These findings suggest that humans possess a rich set of concepts before we learn language,” Spelke added. “Learning a particular language may lead us to favor some of these concepts over others, but the concepts already existed before we put them into words.”
Read more in Nature
Top of page
The Dopamine Reward
May 11, 2004
Researchers, using a new combination of techniques, have discovered that dopamine levels in our brains vary the most in situations where we are unsure if we are going to be rewarded, such as when we are gambling or playing the lottery.
The research results, "Dopamine Transmission in the Human Striatum during Monetary Reward Tasks," were published online April 28 in the Journal of Neuroscience.
Dopamine has long been known to play an important role in how we experience rewards from a variety of natural sources, including food, relationships and sex, as well as from drugs such as cocaine and heroin, but pinning down the precise conditions that cause its release has been difficult.
"Using a combination of techniques, we were actually able to measure release of the dopamine neurotransmitter under natural conditions using monetary reward," said David Zald, assistant professor of psychology at Vanderbilt University.
Zald believes the primary significance of the study is the possibilities it raises for future research on measuring what causes us to experience reward from a variety of sources and what happens in our brains when we are disappointed in our quest for those rewards. The research lays a foundation for a better understanding of what happens in the brain during unpredictable reward situations such as gambling, (or, for that matter forming new friendships) and offers promise for exploring the chemical foundation of problems such as gambling addiction.
Zald and his colleagues used positron emission topography (PET scanners) to view brain activity in nine human research subjects who had been injected with a chemical that binds to dopamine receptors in the brain, but is less able to bind when the brain is releasing dopamine. A decrease in binding to the receptors is associated with an increase in dopamine release, while an increase in binding indicates reduced release of dopamine. This technique allows researchers to study the strength and location of dopamine release more precisely than has previously been possible.
The team studied the subjects under three different scenarios. Under the first scenario, the subject selected one of four cards and knew a monetary reward of $1 was possible but did not know when it would occur. During the second scenario, subjects knew they would receive a reward with every fourth card they selected. Under the third scenario, subjects chose cards but did not receive or expect any rewards.
Zald and his team found that over the course of the experiment, dopamine transmission increased more in one part of the brain in the unpredictable first scenario, while showing decreases in neighboring regions. In contrast, the receipt of a reward under the predictable second scenario did not result in either significant increases or decreases in dopamine transmission.
"It's probably not just the receipt of money, but the conditions under which it occurs which makes a difference," Zald explained.
The increase and suppression were localized to specific, separate regions of the brain, illustrating that variable reward scenarios, like gambling, have a complex effect on the brain. "The most interesting thing we found is that there were areas that showed increased dopamine release during the unpredictable condition, and there were also other areas showing decreased dopamine release, so other than just dopamine as reward, there is a more complicated action occurring."
For us the interesting thing here is that the research ties in with our view of the brain as very much a hunter-gatherer instrument. The situation of gambling with an unpredictable reward is exactly like "primitive" hunting on the African savannah (I've witnessed this--BM). The danger of being attacked by a predator is the gamble, the antelope is the reward. The same process occurs when meeting new people--the danger of rejection or harm is the gamble, their meeting our needs is the reward.
Read more in Journal of Neuroscience
Top of page
New Insights on Sex Drive
April 3, 2004
For almost a decade, researchers at Pfizer struggled to show that Viagra could enhance sexual function in women. Last month, they gave up.
Tests on thousands of women made it clear that the pill, thought able to stir arousal, did not always evoke sexual desire. Viagra's failure underscored the obvious: When it comes to sexuality, men and women to some extent are differently tuned. For men, arousal and desire are often intertwined, while for women, the two are frequently distinct.
Scientists have recently begun to map out this difference in the brain. Male arousal, studies find, is strongly visual, and when men engage in sexual activity or even anticipate it, brain structures once thought to have little connection to sex spring into action. The same brain regions, however, remain relatively quiet when women are aroused.
At the core of the sexual divide, some researchers say, is the amygdala, walnut shaped part of the limbic system, the brain's seat of emotions.
In one recent study, a team of researchers at Emory University had 28 men and women look at erotic photographs while an MRI took snapshots of their brains. A pattern immediately emerged: There was a frenzy of brain activity, particularly in the amygdalae of men. Yet the two groups reported equal arousal most of the time.
"This definitely emphasizes that up until recently the amygdala has been overlooked," said Stephan Hamann, a professor of psychology and the lead author of the study, which was published in Nature Neuroscience.
In another study published last year, researchers in the Netherlands recorded brain activity in men as their female partners brought them to orgasm. The amygdala showed decreased activity during climax. Other studies have suggested that a larger amygdala may lead to a more robust sex drive.
Hamann said the amygdala is known to have intricate connections to primates' visual systems. One reason for the response to visual stimuli in men, he said, could be cultural. Men tend to be inundated with sexual imagery and, possibly, are more likely to seek it out.
Read more in Nature Neuroscience
Top of page
Clever Pretty Polly!
February 18, 2004
Alicia and I are constantly amazed by the way that we humans think we are so unique. We're not. In every single way in which we have tried to differentiate ourselves we have found that there are other creatures with the same attributes as us.
Just to take a few: It used to be thought that we were the only tool-makers. Now we know that bonobos, chimpanzees and crows (to name just a few) make and use tools.
Our psychologists, philosophers and theologians said that what separated us from other members of the animal kingdom was consciousness--the sense of knowing who we were and where we existed in time and space. Well, not so. Neuroscientists discovered a few years ago that we share this with chickens (and virtually all other forms of sentient life).
"Mathematics!" Yelled those who wanted to retain our specialty. Sorry, guys, try again. Other species can count.
"It's our use of language," the humanophiles cried. Not so. Chimpanzees can be taught to use human language and to construct sentences. And not only chimps. The finding of a parrot with an almost unparalleled power to communicate with people has brought scientists up short.
The bird, a captive African grey called N'kisi, has a vocabulary of 950 words, and shows signs of a sense of humor. He invents his own words and phrases if he is confronted with novel ideas with which his existing repertoire cannot cope--just as a human child would do.
N'kisi's remarkable abilities, which are said to include telepathy, is believed to be one of the most advanced users of human language in the animal world. About 100 words are needed for half of all reading in English, so if N'kisi could read he would be able to cope with a wide range of material.
The parrot uses words in context, with past, present and future tenses, and is often inventive. One N'kisi-ism was "flied" for "flew", and another "pretty smell medicine" to describe the aromatherapy oils used by his owner, an artist based in New York.
When he first met Dr Jane Goodall, the renowned chimpanzee expert, after seeing her in a picture with apes, N'kisi said: "Got a chimp?"
He appears to fancy himself as a humourist. When another parrot hung upside down from its perch, he commented: "You got to put this bird on the camera."
Dr Goodall says N'kisi's verbal fireworks are an "outstanding example of interspecies communication".
In an experiment, the bird and his owner were put in separate rooms and filmed as the artist opened random envelopes containing picture cards. Analysis showed the parrot had used appropriate keywords three times more often than would be likely by chance. This was despite the researchers discounting responses like "What ya doing on the phone?" when N'kisi saw a card of a man with a telephone, and "Can I give you a hug?" with one of a couple embracing.
Professor Donald Broom, of the University of Cambridge's School of Veterinary Medicine, said: "The more we look at the cognitive abilities of animals, the more advanced they appear, and the biggest leap of all has been with parrots."
Read more in Science
Top of page
It's Chemistry
February 18, 2004
"I feel my synaptic receptors taking up oxytocin whenever I'm around you. Will you marry me?" There's something rather unromantic about this proposal.
However recent research has highlighted that love is very much a matter of brain chemistry. According to neuroscientist Professor Gareth Leng of Edinburgh University in a recent lecture called "How Does the Brain Fall in Love" oxytocin is the neuroglue that helps bond a mother and her baby. It is also released during childbirth and orgasm. He said it acts like a "master switch" in the brain, opening up new patterns of interaction between nerve cells.
He also claims that people who have fewer of the special brain receptors needed to take up the oxytocin may have difficulties in making successful permanent bonds with their partners.
Research has found that the hormone, which is released into the brain in large amounts during labour and during sexual activity, is an important trigger of maternal behavior in animals. Its crucial role in sexual bonding has been observed by scientists studying the prairie vole.
The prairie vole mates for life and this life-long bond is established over the 48 hours of intense mating activity that is its first experience of sex. According to Professor Leng: "During this time, large amounts of oxytocin are released within the brain. Prairie voles have oxytocin receptors in different parts of their brains, and scientists have found that blocking these receptors prevents the formation of pair-bonding in females. How a single, albeit prolonged, exposure to oxytocin can produce such profound and prolonged changes in behavior is not known, but we are trying to find answers."
Reported in BBC News Online
Top of page
Updated IQ Tests Can Wreak Havoc
December 16, 2003
I always thought that IQ tests were useless and really said very little about the individual. But now researchers from Cornell University have come up with findings that show that they can be positively deadly.
They have found that the year in which IQ is tested can make the difference between life and death for a death row inmate. It also can determine the eligibility of children for special services, adults' Social Security benefits and recruits' suitability for certain military careers.
That's because IQ scores tend to rise 5 to 25 points in a single generation. This so-called "Flynn effect" is corrected by toughening up the test every 15 to 20 years to reset the mean score to 100. A score from a test taken at the end of one cycle can vary widely from a score derived from a test taken at the beginning of the next cycle, when the test is more difficult, says Stephen J Ceci, professor of human development at Cornell.
Ceci and his current and former graduate students found, for example, that the number of children recommended for special services for mild mental retardation tripled during the first five years of a new test compared with the final five years of an old test, despite the fact that there were no real changes in underlying intelligence.
"Our findings imply that some borderline death row inmates or capital murder defendants who were not classified as mentally retarded in childhood because they took an older version of an IQ test might have qualified as retarded if they had taken a more recent test," Ceci says. "That's the difference between being sentenced to life imprisonment versus lethal injection."
The study is published in the October issue of American Psychologist.
The researchers analyzed IQ data from almost 9,000 school psychologist special education assessments in nine school districts across the country to document how the resetting of the IQ test influences mental retardation diagnoses for several years after a new test is introduced.
The consequences of taking intelligence tests at the end or beginning of a test's cycle are most critical, however, when determining whether a death row inmate is mentally competent. Of the 350 people executed since 1990, 112 were known to have IQ scores of 70 or below (the cutoff for mental retardation).
Among children, the researchers found nearly a six-point difference between those taking the two tests. "This variance can make the difference between a child being diagnosed as mentally retarded or not," Ceci says. "This study shows for the first time that two children in the same classroom with the same cognitive ability could be diagnosed differently simply because different test norms were used for each child."
The researchers report that perhaps tens of thousands of children could be affected by these IQ trends over the course of their school years, with far-reaching financial implications. "Our results imply that millions of taxpayers' educational dollars may be misallocated because students are being misdiagnosed every year that an IQ test ages," Ceci points out.
A diagnosis of mental retardation also determines whether a person is eligible for Social Security disability benefits. And the year in which a military recruit takes an IQ test can determine whether he or she is eligible for service or certain occupations and ranks.
"Caution must be used when IQ scores are used to base important financial, social or legal decisions. It may not be sufficient to simply look to see if an IQ score is below some cutoff point. The most important times to be particularly careful are when the test is either at the beginning or the end of its cycle."
Read more in American Psychologist
Top of page
Subtle Racial Bias Makes Communication Difficult
December 2, 2003
A new study highlights how even unintentional racial bias makes problem-solving difficult. The researchers found new evidence using brain imaging that white individuals attempt to control racial bias when exposed to black individuals, and that this act of suppressing bias exhausts mental resources. One would assume that it's also true the other way around.
Published in the online edition of Nature Neuroscience, the study combines the use of functional magnetic resonance imaging (fMRI), which measures brain activity, with other behavioral tests common to research in social and cognitive psychology to determine how white individuals respond to black individuals.
"We were surprised to find that brain activity in response to faces of black individuals predicted how research participants performed on cognitive tasks after actual interracial interactions," says Jennifer Richeson, Assistant Professor of Psychological and Brain Sciences, the lead author on the paper.
Their findings suggest that harboring racial bias, however unintentional, makes negotiating interracial interactions more cognitively demanding. Similar to the depletion of a muscle after intensive exercise, the data suggest that the demands of the interracial interaction result in reduced capacity to engage in subsequent cognitive tasks, say the researchers.
For the study, thirty white individuals were measured for racial bias, which involved a computer test to record the ease with which individuals associate white American and black American racial groups with positive and negative concepts. Racial bias is measured by a pattern in which individuals take longer to associate the white Americans with negative concepts and black Americans with positive concepts. The study participants then interacted with either a black or a white individual, and afterward they were asked to complete an unrelated cognitive task in which they had to inhibit instinctual responses. In a separate fMRI session, these individuals were presented with photographs of unfamiliar black male and white male faces, and the activity of brain regions thought to be critical to cognitive control was assessed.
"We found that white people with higher scores on the racial bias measure experienced greater neural activity in response to the photographs of black males," says Richeson. "This heightened activity was in the right dorsolateral prefrontal cortex, an area in the front of the brain that has been linked to the control of thoughts and behaviors. Plus, these same individuals performed worse on the cognitive test after an actual interaction with a black male, suggesting that they may have been depleted of the necessary resources to complete the task."
According to Richeson, most people find it unacceptable to behave in prejudiced ways during interracial interactions and make an effort to avoid doing so, regardless of their level of racial bias. A different research project by Richeson and her colleagues suggested that these efforts could leave individuals temporarily depleted of the resources needed to perform optimally on certain cognitive tasks. This new study by Richeson provides striking evidence that supports the idea that interracial contact temporarily impairs cognitive task performance.
These results suggest, according to the researchers, that harboring racial bias in an increasingly diverse society may be bad for one's cognitive performance. Bad for your relationships as well, I would have thought!
Read more in Nature Neuroscience
Top of page
Adolescent Steroid Use Causes Long Term Aggression
December 2, 2003
With the recent revelations about steroid use in Major League Baseball and the bust a few weeks ago of several Oakland Raiders players for drug abuse, Northeastern University psychology professor Richard Melloni, who studies the link between steroid use and aggression, has recently found evidence that use of anabolic steroids may have long-term effects on players' behavior and aggression levels well after they stop abusing these performance enhancing drugs.
Melloni and doctoral student Jill Grimes have been studying how steroids used during adolescence may permanently alter the brain's ability to produce serotonin. In their experiments, adolescent Syrian hamsters--given their similar brain circuitry to human adolescents--were administered doses of anabolic steroids and then measured for aggressiveness over certain periods of time.
In their findings, published this week in Hormones and Behavior, they conclude that there is indeed a lengthy price--namely long-term aggression--to pay for drug abuse even after the ingestion of steroids ceases.
"We know testosterone or steroids affect the development of serotonin nerve cells, which, in turn, decreases serotonin availability in the brain," Melloni says. "The serotonin neural system is still developing during adolescence and the use of anabolic steroids during this critical period appears to have immediate and longer-term neural and behavioral consequences. What we know at this point is that aggressiveness doesn't simply cease after the ingestion of steroids does."
Read more in Hormones and Behavior
Top of page
RELATED LINKS
Check our event schedule for workshops and seminars.
About the Author
Dr Bob Murray is a widely published psychologist and expert on emotional health and optimal relationships. Together with his wife and long-term collaborator Alicia Fortinberry, he is founder of the highly successful Uplift Program, and author of Raising an Optimistic Child (McGraw-Hill, 2006) and Creating Optimism (McGraw-Hill, 2004).
Do you like our site? Recommend this page to a friend!
|
