Neuroscience

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Posts tagged dopamine

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Researchers find epigenetic tie to neuropsychiatric disorders

Dysfunction in dopamine signaling profoundly changes the activity level of about 2,000 genes in the brain’s prefrontal cortex and may be an underlying cause of certain complex neuropsychiatric disorders, such as schizophrenia, according to UC Irvine scientists.

This epigenetic alteration of gene activity in brain cells that receive this neurotransmitter showed for the first time that dopamine deficiencies can affect a variety of behavioral and physiological functions regulated in the prefrontal cortex.

The study, led by Emiliana Borrelli, a UCI professor of microbiology & molecular genetics, appears online in the journal Molecular Psychiatry.

“Our work presents new leads to understanding neuropsychiatric disorders,” Borrelli said. “Genes previously linked to schizophrenia seem to be dependent on the controlled release of dopamine at specific locations in the brain. Interestingly, this study shows that altered dopamine levels can modify gene activity through epigenetic mechanisms despite the absence of genetic mutations of the DNA.”

Dopamine is a neurotransmitter that acts within certain brain circuitries to help manage functions ranging from movement to emotion. Changes in the dopaminergic system are correlated with cognitive, motor, hormonal and emotional impairment. Excesses in dopamine signaling, for example, have been identified as a trigger for neuropsychiatric disorder symptoms.

Borrelli and her team wanted to understand what would happen if dopamine signaling was hindered. To do this, they used mice that lacked dopamine receptors in midbrain neurons, which radically affected regulated dopamine synthesis and release.

The researchers discovered that this receptor mutation profoundly altered gene expression in neurons receiving dopamine at distal sites in the brain, specifically in the prefrontal cortex. Borrelli said they observed a remarkable decrease in expression levels of some 2,000 genes in this area, coupled with a widespread increase in modifications of basic DNA proteins called histones – particularly those associated with reduced gene activity.

Borrelli further noted that the dopamine receptor-induced reprogramming led to psychotic-like behaviors in the mutant mice and that prolonged treatment with a dopamine activator restored regular signaling, pointing to one possible therapeutic approach.

The researchers are continuing their work to gain more insights into the genes altered by this dysfunctional dopamine signaling.

(Source: news.uci.edu)

Filed under dopaminergic neurons dopamine neuropsychiatric disorders gene activity brain cells epigenetics neuroscience science

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Cinnamon May Be Used to Halt the Progression of Parkinson’s disease
Neurological scientists at Rush University Medical Center have found that using cinnamon, a common food spice and flavoring material, can reverse the biomechanical, cellular and anatomical changes that occur in the brains of mice with Parkinson’s disease (PD). The results of the study were recently published in the June 20 issue of the Journal of Neuroimmune Pharmacology.
“Cinnamon has been used widely as a spice throughout the world for centuries,” said Kalipada Pahan, PhD, study lead researcher and the Floyd A. Davis professor of neurology at Rush. “This could potentially be one of the safest approaches to halt disease progression in Parkinson’s patients.”
“Cinnamon is metabolized in the liver to sodium benzoate, which is an FDA-approved drug used in the treatment for hepatic metabolic defects associated with hyperammonemia,” said Pahan. It is also widely used as a food preservative due to its microbiocidal effect.
Chinese cinnamon (Cinnamonum cassia) and original Ceylon cinnamon (Cinnamonum verum) are two major types of cinnamon that are available in the US.
“Although both types of cinnamon are metabolized into sodium benzoate, by mass spectrometric analysis, we have seen that Ceylon cinnamon is much more pure than Chinese cinnamon as the latter contains coumarin, a hepatotoxic molecule,” said Pahan.
“Understanding how the disease works is important to developing effective drugs that protect the brain and stop the progression of PD,” said Pahan. “It is known that some important proteins like Parkin and DJ-1 decrease in the brain of PD patients.”
The study found that after oral feeding, ground cinnamon is metabolized into sodium benzoate, which then enters into the brain, stops the loss of Parkin and DJ-1, protects neurons, normalizes neurotransmitter levels, and improves motor functions in mice with PD.
This research was supported by grants from National Institutes of Health.
“Now we need to translate this finding to the clinic and test ground cinnamon in patients with PD. If these results are replicated in PD patients, it would be a remarkable advance in the treatment of this devastating neurodegenerative disease,” said Dr. Pahan.
Parkinson’s disease is a slowly progressive disease that affects a small area of cells within the mid-brain known as the substantia nigra. Gradual degeneration of these cells causes a reduction in a vital chemical neurotransmitter, dopamine. The decrease in dopamine results in one or more of the classic signs of Parkinson’s disease that includes: resting tremor on one side of the body; generalized slowness of movement; stiffness of limbs; and gait or balance problems. The cause of the disease is unknown. Both environmental and genetic causes of the disease have been postulated.
Parkinson’s disease affects about 1.2 million patients in the United States and Canada. Although 15 percent of patients are diagnosed before age 50, it is generally considered a disease that targets older adults, affecting one of every 100 persons over the age of 60. This disease appears to be slightly more common in men than women.

Cinnamon May Be Used to Halt the Progression of Parkinson’s disease

Neurological scientists at Rush University Medical Center have found that using cinnamon, a common food spice and flavoring material, can reverse the biomechanical, cellular and anatomical changes that occur in the brains of mice with Parkinson’s disease (PD). The results of the study were recently published in the June 20 issue of the Journal of Neuroimmune Pharmacology.

“Cinnamon has been used widely as a spice throughout the world for centuries,” said Kalipada Pahan, PhD, study lead researcher and the Floyd A. Davis professor of neurology at Rush. “This could potentially be one of the safest approaches to halt disease progression in Parkinson’s patients.”

“Cinnamon is metabolized in the liver to sodium benzoate, which is an FDA-approved drug used in the treatment for hepatic metabolic defects associated with hyperammonemia,” said Pahan. It is also widely used as a food preservative due to its microbiocidal effect.

Chinese cinnamon (Cinnamonum cassia) and original Ceylon cinnamon (Cinnamonum verum) are two major types of cinnamon that are available in the US.

“Although both types of cinnamon are metabolized into sodium benzoate, by mass spectrometric analysis, we have seen that Ceylon cinnamon is much more pure than Chinese cinnamon as the latter contains coumarin, a hepatotoxic molecule,” said Pahan.

“Understanding how the disease works is important to developing effective drugs that protect the brain and stop the progression of PD,” said Pahan. “It is known that some important proteins like Parkin and DJ-1 decrease in the brain of PD patients.”

The study found that after oral feeding, ground cinnamon is metabolized into sodium benzoate, which then enters into the brain, stops the loss of Parkin and DJ-1, protects neurons, normalizes neurotransmitter levels, and improves motor functions in mice with PD.

This research was supported by grants from National Institutes of Health.

Now we need to translate this finding to the clinic and test ground cinnamon in patients with PD. If these results are replicated in PD patients, it would be a remarkable advance in the treatment of this devastating neurodegenerative disease,” said Dr. Pahan.

Parkinson’s disease is a slowly progressive disease that affects a small area of cells within the mid-brain known as the substantia nigra. Gradual degeneration of these cells causes a reduction in a vital chemical neurotransmitter, dopamine. The decrease in dopamine results in one or more of the classic signs of Parkinson’s disease that includes: resting tremor on one side of the body; generalized slowness of movement; stiffness of limbs; and gait or balance problems. The cause of the disease is unknown. Both environmental and genetic causes of the disease have been postulated.

Parkinson’s disease affects about 1.2 million patients in the United States and Canada. Although 15 percent of patients are diagnosed before age 50, it is generally considered a disease that targets older adults, affecting one of every 100 persons over the age of 60. This disease appears to be slightly more common in men than women.

Filed under parkinson's disease cinnamon parkin dopaminergic neurons dopamine neuroscience science

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The Biology of Addiction Risk Looks Like Addiction

Research suggests that people at increased risk for developing addiction share many of the same neurobiological signatures of people who have already developed addiction. This similarity is to be expected, as individuals with family members who have struggled with addiction are over-represented in the population of addicted people.

However, a generation of animal research supports the hypothesis that the addiction process changes the brain in ways that converge with the distinctive neurobiology of the heritable risk for addiction. In other words, the more one uses addictive substances, the more one’s brain acquires the profile of someone who has inherited a risk for addiction.

One such change is a reduction in striatal dopamine release. Dopamine is a key brain chemical messenger involved in reward-related behaviors. Disturbances in dopamine signaling appear to contribute to reward processing that biases people to seek drug-like rewards and to develop drug-taking habits.

In the current issue of Biological Psychiatry, researchers at McGill University report that individuals at high risk for addiction show the same reduced dopamine response often observed in addicted individuals, identifying a new link between addiction risk and addiction in humans.

Dr. Marco Leyton and his colleagues recruited young adults, aged 18 to 25, who were classified into three groups: 1) a high-risk group of occasional stimulant users with an extensive family history of substance abuse; 2) a comparison group of occasional stimulant users with no family history; and 3) a second comparison group of individuals with no history of stimulant use and no known risk factors for addiction. Volunteers underwent a positron emission tomography (PET) scan involving the administration of amphetamine, which enabled the researchers to measure their dopamine response.

The authors found that the high-risk group of non-dependent young adults with extensive family histories of addiction displayed markedly reduced dopamine responses in comparison with both stimulant-naïve subjects and non-dependent users with no family history.

“This interesting new parallel between addiction risk and addiction may help to focus our attention on reward-related processes that contribute to the development of addiction, perhaps informing prevention strategies,” said Dr. John Krystal, Editor of Biological Psychiatry.

Leyton, a Professor at McGill University, said, “Young adults at risk of addictions have a strikingly disturbed brain dopamine reward system response when they are administered amphetamine. Past drug use seemed to aggravate the dopamine response also but this was not a sufficient explanation. Instead, the disturbance may be a heritable biological marker that could identify those at highest risk.”

This finding suggests that there are common brain mechanisms that promote the use of addictive substances in vulnerable people and in people who have long-standing habitual substance use.

Better understanding this biology may help to advance our understanding of how people develop addiction problems, as well as providing hints related to biological mechanisms that might be targeted for prevention and treatment.

(Source: elsevier.com)

Filed under addiction reward system dopamine neuroscience science

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Addiction starts with an overcorrection in the brain
The National Institutes of Health has turned to neuroscientists at the nation’s most “Stone Cold Sober” university for help finding ways to treat drug and alcohol addiction.
Brigham Young University professor Scott Steffensen and his collaborators have published three new scientific papers that detail the brain mechanisms involved with addictive substances. And the NIH thinks Steffensen’s on the right track, as evidenced by a $2-million grant that will help fund projects in his BYU lab for the next five years.
“Addiction is a brain disease that could be treated like any other disease,” Steffensen said. “I wouldn’t be as motivated to do this research, or as passionate about the work, if I didn’t think a cure was possible.” 
Steffensen’s research suggests that the process of a brain becoming addicted is similar to a driver overcorrecting a vehicle. When drugs and alcohol release unnaturally high levels of dopamine in the brain’s pleasure system, oxidative stress occurs in the brain.
Steffensen and his collaborators have found that the brain responds by generating a protein called BDNF (brain derived neurotrophic factor). This correction suppresses the brain’s normal production of dopamine long after someone comes down from a high. Not having enough dopamine is what causes the pains, distress and anxiety of withdrawal.
“The body attempts to compensate for unnatural levels of dopamine, but a pathological process occurs,” Steffensen said. “We think it all centers around a subset of neurons that ordinarily put the brakes on dopamine release.”
A group of undergraduate students work in Steffensen’s lab along with post-doctoral fellows and graduate students. Jennifer Blanchard Mabey, a graduate student in neuroscience, co-authored a paper about withdrawal that is in the current issue of The Journal of Neuroscience.
“It’s rewarding to see that your research efforts place another small piece in the enormous addiction puzzle,” said Mabey.
A separate study, co-authored by Steffensen and Ph.D. candidates Nathan Schilaty and David Hedges, explains how nicotine and alcohol interact in the brain.
“Addiction is a huge concern in our society and is very misunderstood,” Schilaty said. “Our research is helping us to formulate ideas on how we can better help these individuals through non-invasive and non-pharmacological means.”
Eun Young Jang, a post-doctoral fellow in Steffensen’s lab, authored a third paper for Addiction Biology describing the effects of cocaine addiction on the brain’s reward circuitry.
In these three research papers, dopamine is the common thread.
“I am optimistic that in the near future medical science will be able to reverse the brain changes in dopamine transmission that occur with drug dependence and return an ‘addict’ to a relatively normal state,” Steffensen said. “Then the addict will be in a better position to make rational decisions regarding their behavior and will be empowered to remain drug free.”

Addiction starts with an overcorrection in the brain

The National Institutes of Health has turned to neuroscientists at the nation’s most “Stone Cold Sober” university for help finding ways to treat drug and alcohol addiction.

Brigham Young University professor Scott Steffensen and his collaborators have published three new scientific papers that detail the brain mechanisms involved with addictive substances. And the NIH thinks Steffensen’s on the right track, as evidenced by a $2-million grant that will help fund projects in his BYU lab for the next five years.

“Addiction is a brain disease that could be treated like any other disease,” Steffensen said. “I wouldn’t be as motivated to do this research, or as passionate about the work, if I didn’t think a cure was possible.” 

Steffensen’s research suggests that the process of a brain becoming addicted is similar to a driver overcorrecting a vehicle. When drugs and alcohol release unnaturally high levels of dopamine in the brain’s pleasure system, oxidative stress occurs in the brain.

Steffensen and his collaborators have found that the brain responds by generating a protein called BDNF (brain derived neurotrophic factor). This correction suppresses the brain’s normal production of dopamine long after someone comes down from a high. Not having enough dopamine is what causes the pains, distress and anxiety of withdrawal.

“The body attempts to compensate for unnatural levels of dopamine, but a pathological process occurs,” Steffensen said. “We think it all centers around a subset of neurons that ordinarily put the brakes on dopamine release.”

A group of undergraduate students work in Steffensen’s lab along with post-doctoral fellows and graduate students. Jennifer Blanchard Mabey, a graduate student in neuroscience, co-authored a paper about withdrawal that is in the current issue of The Journal of Neuroscience.

“It’s rewarding to see that your research efforts place another small piece in the enormous addiction puzzle,” said Mabey.

A separate study, co-authored by Steffensen and Ph.D. candidates Nathan Schilaty and David Hedges, explains how nicotine and alcohol interact in the brain.

“Addiction is a huge concern in our society and is very misunderstood,” Schilaty said. “Our research is helping us to formulate ideas on how we can better help these individuals through non-invasive and non-pharmacological means.”

Eun Young Jang, a post-doctoral fellow in Steffensen’s lab, authored a third paper for Addiction Biology describing the effects of cocaine addiction on the brain’s reward circuitry.

In these three research papers, dopamine is the common thread.

“I am optimistic that in the near future medical science will be able to reverse the brain changes in dopamine transmission that occur with drug dependence and return an ‘addict’ to a relatively normal state,” Steffensen said. “Then the addict will be in a better position to make rational decisions regarding their behavior and will be empowered to remain drug free.”

Filed under addiction brain-derived neurotrophic factor opiates dopamine neuroscience science

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Boost for dopamine packaging protects brain in Parkinson’s model

Researchers from Emory’s Rollins School of Public Health discovered that an increase in the protein that helps store dopamine, a critical brain chemical, led to enhanced dopamine neurotransmission and protection from a Parkinson’s disease-related neurotoxin in mice.

Dopamine and related neurotransmitters are stored in small storage packages called vesicles by the vesicular monoamine transporter (VMAT2). When released from these packages dopamine can help regulate movement, pleasure and emotional response. Low dopamine levels are associated with neurodegenerative diseases such as Parkinson’s disease and recent research has shown that VMAT2 function is impaired in people with the disease.

Lead researcher Gary W. Miller, PhD professor and associate dean for research at the Rollins School of Public Health and his team generated transgenic mice with increased levels of VMAT2 and found it led to an increase in dopamine release. In addition, the group found improved outcomes on anxiety and depressive behaviors, increased movement, and protection from MPTP, the chemical that can cause Parkinson’s disease-related damage in the brain.

The complete study is available in the June 17, 2014 edition of Proceedings of the National Academy of Sciences (PNAS).

According to Miller, “This work suggests that enhanced vesicular filling can be sustained over time and may be a viable
 therapeutic approach for a variety of central nervous system disorders that involve the storage and release of dopamine, serotonin or norepinephrine.”

(Source: news.emory.edu)

Filed under parkinson's disease dopamine VMAT2 neurotransmitters neuroscience science

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MRI Technique May Help Prevent ADHD Misdiagnosis
Brain iron levels offer a potential biomarker in the diagnosis of attention deficit hyperactivity disorder (ADHD) and may help physicians and parents make better informed treatment decisions, according to new research published online in the journal Radiology.
ADHD is a common disorder in children and adolescents that can continue into adulthood. Symptoms include hyperactivity and difficulty staying focused, paying attention and controlling behavior. The American Psychiatric Association reports that ADHD affects 3 to 7 percent of school-age children.
Psychostimulant medications such as Ritalin are among the drugs commonly used to reduce ADHD symptoms. Psychostimulants affect levels of dopamine, a neurotransmitter in the brain associated with addiction.
"Much debate and concern has emerged regarding the continual rise of ADHD diagnosis in the U.S. given that two-thirds of those diagnosed receive psychostimulant medications," said Vitria Adisetiyo, Ph.D., postdoctoral research fellow at the Medical University of South Carolina in Charleston, S.C. "We wanted to see if we could identify brain iron as a potential noninvasive biomarker for medication-naïve ADHD to prevent misdiagnosis."
For the study, the research team measured brain iron levels in 22 children and adolescents with ADHD, 12 of whom had never been on medication for their condition (medication naïve), and 27 healthy control children and adolescents using a magnetic resonance imaging (MRI) technique called magnetic field correlation imaging. The technique was introduced in 2006 by study co-authors and faculty members Joseph A. Helpern, Ph.D., and Jens H. Jensen, Ph.D. No contrast agents were used, and blood iron levels in the body were measured using a blood draw.
The results showed that the 12 ADHD medication-naïve patients had significantly lower brain iron levels than the 10 ADHD patients who had been on psychostimulant medication and the 27 children and adolescents in the control group. In contrast, ADHD patients with a history of psychostimulant medication treatment had brain iron levels comparable to controls, suggesting that brain iron may increase to normal levels with psychostimulant treatment.
"Our research suggests that iron absorption into the brain may be abnormal in ADHD given that atypical brain iron levels are found even when blood iron levels in the body are normal," Dr. Adisetiyo said. "We found no differences in blood iron measures between controls, medication-naïve ADHD patients or pscyhostimulant-medicated ADHD patients."
Magnetic field correlation imaging’s ability to noninvasively detect the low iron levels may help improve ADHD diagnosis and guide optimal treatment. Currently, ADHD diagnosis is based only on subjective clinical interviews and questionnaires. Having a biological biomarker may help inform clinical diagnosis, particularly in borderline cases, Dr. Adisetiyo noted.
If the results can be replicated in larger studies, magnetic field correlation might have a future role in determining which patients would benefit from psychostimulants—an important consideration because the drugs can become addictive if taken inappropriately and lead to abuse of other drugs like cocaine.
"We want the public to know that progress is being made in identifying potential noninvasive biological biomarkers of ADHD which may help to prevent misdiagnosis," Dr. Adisetiyo said. "We are currently testing our findings in a larger cohort to confirm that measuring brain iron levels in ADHD is indeed a reliable and clinically feasible biomarker."

MRI Technique May Help Prevent ADHD Misdiagnosis

Brain iron levels offer a potential biomarker in the diagnosis of attention deficit hyperactivity disorder (ADHD) and may help physicians and parents make better informed treatment decisions, according to new research published online in the journal Radiology.

ADHD is a common disorder in children and adolescents that can continue into adulthood. Symptoms include hyperactivity and difficulty staying focused, paying attention and controlling behavior. The American Psychiatric Association reports that ADHD affects 3 to 7 percent of school-age children.

Psychostimulant medications such as Ritalin are among the drugs commonly used to reduce ADHD symptoms. Psychostimulants affect levels of dopamine, a neurotransmitter in the brain associated with addiction.

"Much debate and concern has emerged regarding the continual rise of ADHD diagnosis in the U.S. given that two-thirds of those diagnosed receive psychostimulant medications," said Vitria Adisetiyo, Ph.D., postdoctoral research fellow at the Medical University of South Carolina in Charleston, S.C. "We wanted to see if we could identify brain iron as a potential noninvasive biomarker for medication-naïve ADHD to prevent misdiagnosis."

For the study, the research team measured brain iron levels in 22 children and adolescents with ADHD, 12 of whom had never been on medication for their condition (medication naïve), and 27 healthy control children and adolescents using a magnetic resonance imaging (MRI) technique called magnetic field correlation imaging. The technique was introduced in 2006 by study co-authors and faculty members Joseph A. Helpern, Ph.D., and Jens H. Jensen, Ph.D. No contrast agents were used, and blood iron levels in the body were measured using a blood draw.

The results showed that the 12 ADHD medication-naïve patients had significantly lower brain iron levels than the 10 ADHD patients who had been on psychostimulant medication and the 27 children and adolescents in the control group. In contrast, ADHD patients with a history of psychostimulant medication treatment had brain iron levels comparable to controls, suggesting that brain iron may increase to normal levels with psychostimulant treatment.

"Our research suggests that iron absorption into the brain may be abnormal in ADHD given that atypical brain iron levels are found even when blood iron levels in the body are normal," Dr. Adisetiyo said. "We found no differences in blood iron measures between controls, medication-naïve ADHD patients or pscyhostimulant-medicated ADHD patients."

Magnetic field correlation imaging’s ability to noninvasively detect the low iron levels may help improve ADHD diagnosis and guide optimal treatment. Currently, ADHD diagnosis is based only on subjective clinical interviews and questionnaires. Having a biological biomarker may help inform clinical diagnosis, particularly in borderline cases, Dr. Adisetiyo noted.

If the results can be replicated in larger studies, magnetic field correlation might have a future role in determining which patients would benefit from psychostimulants—an important consideration because the drugs can become addictive if taken inappropriately and lead to abuse of other drugs like cocaine.

"We want the public to know that progress is being made in identifying potential noninvasive biological biomarkers of ADHD which may help to prevent misdiagnosis," Dr. Adisetiyo said. "We are currently testing our findings in a larger cohort to confirm that measuring brain iron levels in ADHD is indeed a reliable and clinically feasible biomarker."

Filed under ADHD dopamine psychostimulants iron neuroscience science

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(Image caption: Brain scans show high activity in the medial prefrontal cortex (top) and striatum (bottom) while playing a competitive game. UC Berkeley and UIUC researchers have now found genetic variations in dopamine-regulating genes in the prefrontal cortex and striatum associated with differences in belief learning and reinforcement learning, respectively. Credit: Ming Hsu)
Your genes affect your betting behavior
Investors and gamblers take note: your betting decisions and strategy are determined, in part, by your genes.
Researchers from the University of California, Berkeley, National University of Singapore and University of Illinois at Urbana-Champaign (UIUC) have shown that betting decisions in a simple competitive game are influenced by the specific variants of dopamine-regulating genes in a person’s brain.
Dopamine is a neurotransmitter – a chemical released by brain cells to signal other brain cells – that is a key part of the brain’s reward and pleasure-seeking system. Dopamine deficiency leads to Parkinson’s disease, while disruption of the dopamine network is linked to numerous psychiatric and neurodegenerative disorders, including schizophrenia, depression and dementia.
While previous studies have shown the important role of the neurotransmitter dopamine in social interactions, this is the first study tying these interactions to specific genes that govern dopamine functioning.
“This study shows that genes influence complex social behavior, in this case strategic behavior,” said study leader Ming Hsu, an assistant professor of marketing in UC Berkeley’s Haas School of Business and a member of the Helen Wills Neuroscience Institute. “We now have some clues about the neural mechanisms through which our genes affect behavior.”
The implications for business are potentially vast but unclear, Hsu said, though one possibility is training workforces to be more strategic. But the findings could significantly affect our understanding of diseases involving dopamine, such as schizophrenia, as well as disorders of social interaction, such as autism.
“When people talk about dopamine dysfunction, schizophrenia is one of the first diseases that come to mind,” Hsu said, noting that the disease involves a very complex pattern of social and decision making deficits. “To the degree that we can better understand ubiquitous social interactions in strategic settings, it may help us understand how to characterize and eventually treat the social deficits that are symptoms of diseases like schizophrenia.”
Hsu, UIUC graduate student Eric Set and their colleagues, including Richard P. Ebstein and Soo Hong Chew from the National University of Singapore, will publish their findings the week of June 16 in the online early edition of the Proceedings of the National Academy of Sciences.
Two brain areas involved in competition
Hsu established two years ago that when people engage in competitive social interactions, such as betting games, they primarily call upon two areas of the brain: the medial prefrontal cortex, which is the executive part of the brain, and the striatum, which deals with motivation and is crucial for learning to acquire rewards. Functional magnetic resonance imaging (fMRI) scans showed that people playing these games displayed intense activity in these areas.
“If you think of the brain as a computing machine, these are areas that take inputs, crank them through an algorithm, and translate them into behavioral outputs,” Hsu said. “What is really interesting about these areas is that both are innervated by neurons that use dopamine.”
Hsu and Set of UIUC’s Department of Economics wanted to determine which genes involved in regulating dopamine concentrations in these brain areas were associated with strategic thinking, so they enlisted as subjects a group of 217 undergraduates at the National University of Singapore, all of whom had had their genomes scanned for some 700,000 genetic variants. The researchers focused on only 143 variants within 12 genes involved in regulating dopamine. Some of the 12 are primarily involved in regulating dopamine in the prefrontal cortex, while others primarily regulate dopamine in the striatum.
The competition was a game called patent race, commonly used by social scientists to study social interactions. It involves one person betting, via computer, with an anonymous opponent.
“We know from brain imaging studies that when people compete against one another, they actually engage in two distinct types of learning processes,” Set said, referring to Hsu’s 2012 study. “One type involves learning purely from the consequences of your own actions, called reinforcement learning. The other is a bit more sophisticated, called belief learning, where people try to make a mental model of the other players, in order to anticipate and respond to their actions.”
Trial-and-error learning vs belief learning
Using a mathematical model of brain function during competitive social interactions, Hsu and Set correlated performance in reinforcement learning and belief learning with different variants or mutations of the 12 dopamine-related genes, and discovered a distinct difference.
They found that differences in belief learning – the degree to which players were able to anticipate and respond to the actions of others, or to imagine what their competitor is thinking and respond strategically – was associated with variation in three genes which primarily affect dopamine functioning in the medial prefrontal cortex.
In contrast, differences in trial-and-error reinforcement learning – how quickly they forget past experiences and how quickly they change strategy – was associated with variation in two genes that primarily affect striatal dopamine.
Hsu said that the findings correlate well with previous brain studies showing that the prefrontal cortex is involved in belief learning, while the striatum is involved in reinforcement learning.
“We were surprised by the degree of overlap, but it hints at the power of studying the neural and genetic levels under a single mathematical framework, which is only beginning in this area,” he said.
Hsu is currently collaborating with other scientists to correlate career achievements in older adults with genes and performance on competitive games, to see which brain regions and types of learning are most important for different kinds of success in life.

(Image caption: Brain scans show high activity in the medial prefrontal cortex (top) and striatum (bottom) while playing a competitive game. UC Berkeley and UIUC researchers have now found genetic variations in dopamine-regulating genes in the prefrontal cortex and striatum associated with differences in belief learning and reinforcement learning, respectively. Credit: Ming Hsu)

Your genes affect your betting behavior

Investors and gamblers take note: your betting decisions and strategy are determined, in part, by your genes.

Researchers from the University of California, Berkeley, National University of Singapore and University of Illinois at Urbana-Champaign (UIUC) have shown that betting decisions in a simple competitive game are influenced by the specific variants of dopamine-regulating genes in a person’s brain.

Dopamine is a neurotransmitter – a chemical released by brain cells to signal other brain cells – that is a key part of the brain’s reward and pleasure-seeking system. Dopamine deficiency leads to Parkinson’s disease, while disruption of the dopamine network is linked to numerous psychiatric and neurodegenerative disorders, including schizophrenia, depression and dementia.

While previous studies have shown the important role of the neurotransmitter dopamine in social interactions, this is the first study tying these interactions to specific genes that govern dopamine functioning.

“This study shows that genes influence complex social behavior, in this case strategic behavior,” said study leader Ming Hsu, an assistant professor of marketing in UC Berkeley’s Haas School of Business and a member of the Helen Wills Neuroscience Institute. “We now have some clues about the neural mechanisms through which our genes affect behavior.”

The implications for business are potentially vast but unclear, Hsu said, though one possibility is training workforces to be more strategic. But the findings could significantly affect our understanding of diseases involving dopamine, such as schizophrenia, as well as disorders of social interaction, such as autism.

“When people talk about dopamine dysfunction, schizophrenia is one of the first diseases that come to mind,” Hsu said, noting that the disease involves a very complex pattern of social and decision making deficits. “To the degree that we can better understand ubiquitous social interactions in strategic settings, it may help us understand how to characterize and eventually treat the social deficits that are symptoms of diseases like schizophrenia.”

Hsu, UIUC graduate student Eric Set and their colleagues, including Richard P. Ebstein and Soo Hong Chew from the National University of Singapore, will publish their findings the week of June 16 in the online early edition of the Proceedings of the National Academy of Sciences.

Two brain areas involved in competition

Hsu established two years ago that when people engage in competitive social interactions, such as betting games, they primarily call upon two areas of the brain: the medial prefrontal cortex, which is the executive part of the brain, and the striatum, which deals with motivation and is crucial for learning to acquire rewards. Functional magnetic resonance imaging (fMRI) scans showed that people playing these games displayed intense activity in these areas.

“If you think of the brain as a computing machine, these are areas that take inputs, crank them through an algorithm, and translate them into behavioral outputs,” Hsu said. “What is really interesting about these areas is that both are innervated by neurons that use dopamine.”

Hsu and Set of UIUC’s Department of Economics wanted to determine which genes involved in regulating dopamine concentrations in these brain areas were associated with strategic thinking, so they enlisted as subjects a group of 217 undergraduates at the National University of Singapore, all of whom had had their genomes scanned for some 700,000 genetic variants. The researchers focused on only 143 variants within 12 genes involved in regulating dopamine. Some of the 12 are primarily involved in regulating dopamine in the prefrontal cortex, while others primarily regulate dopamine in the striatum.

The competition was a game called patent race, commonly used by social scientists to study social interactions. It involves one person betting, via computer, with an anonymous opponent.

“We know from brain imaging studies that when people compete against one another, they actually engage in two distinct types of learning processes,” Set said, referring to Hsu’s 2012 study. “One type involves learning purely from the consequences of your own actions, called reinforcement learning. The other is a bit more sophisticated, called belief learning, where people try to make a mental model of the other players, in order to anticipate and respond to their actions.”

Trial-and-error learning vs belief learning

Using a mathematical model of brain function during competitive social interactions, Hsu and Set correlated performance in reinforcement learning and belief learning with different variants or mutations of the 12 dopamine-related genes, and discovered a distinct difference.

They found that differences in belief learning – the degree to which players were able to anticipate and respond to the actions of others, or to imagine what their competitor is thinking and respond strategically – was associated with variation in three genes which primarily affect dopamine functioning in the medial prefrontal cortex.

In contrast, differences in trial-and-error reinforcement learning – how quickly they forget past experiences and how quickly they change strategy – was associated with variation in two genes that primarily affect striatal dopamine.

Hsu said that the findings correlate well with previous brain studies showing that the prefrontal cortex is involved in belief learning, while the striatum is involved in reinforcement learning.

“We were surprised by the degree of overlap, but it hints at the power of studying the neural and genetic levels under a single mathematical framework, which is only beginning in this area,” he said.

Hsu is currently collaborating with other scientists to correlate career achievements in older adults with genes and performance on competitive games, to see which brain regions and types of learning are most important for different kinds of success in life.

Filed under dopamine genes prefrontal cortex striatum learning neuroscience science

100 notes

Hunting down the trigger for Parkinson’s: failing dopamine pump damages brain cells

A study group at the Medical University of Vienna’s Centre for Brain Research has investigated the function of an intracellular dopamine pump in Parkinson’s patients compared to a healthy test group. It turned out that this pump is less effective at pumping out dopamine and storing it in the brain cells of Parkinson’s sufferers. If dopamine is not stored correctly, however, it can cause self-destruction of the affected nerve cells.

image

In the brain, dopamine mediates the exchange of information between different neurons and, to help it do this, it is continuously reformed at the contact points between the corresponding nerve cells. It is stored in structures known as vesicles (intracellular bubbles) and it is released when required. In people with Parkinson’s disease, the death of these nerve cells causes a lack of dopamine, and this in turn causes the familiar movement problems such as motor retardation, stiffness of the muscles and tremors.

More than 50 years ago, in the Institute of Pharmacology at the University of Vienna (now the MedUni Vienna), Herbert Ehringer and Oleh Hornykiewicz discovered that Parkinson’s disease is caused by a lack of dopamine in certain regions of the brain. This discovery enabled Hornykiewicz to introduce the amino acid L-DOPA into the treatment of Parkinson’s to substitute the dopamine and make the symptoms of the condition manageable for years.

The reasons for the death of nerve cells in Parkinson’s disease are not yet fully understood, however, which is why it is still not possible to prevent the disease from developing. Nevertheless, dopamine itself, if it is not stored correctly in vesicles, can cause self-destruction of the affected nerve cells.

Now, a further step forward has been taken in the research into the causes of this disease: a study at the MedUni Vienna’s Centre for Brain Research, led by Christian Pifl and the now 87-year-old Oleh Hornykiewicz, compared the brains of deceased Parkinson’s patients with those of a neurologically healthy control group. For the first time, it was possible to prepare the dopamine-storing vesicles from the brains so that their ability to store dopamine by pumping it in could be measured in quantitative terms.

It turned out that the pumps in the vesicles of Parkinson’s sufferers pumped the dopamine out less efficiently. “This pump deficiency and the associated reduction in dopamine storage capacity of the Parkinson’s vesicles could lead to dopamine collecting in the nerve cells, developing its toxic effect and destroying the nerve cells,” explains Christian Pifl.

(Source: meduniwien.ac.at)

Filed under parkinson's disease dopamine striatum nerve cells neuroscience science

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Mice with ‘mohawks’ help scientists link autism to 2 biological pathways in brain
"Aha" moments are rare in medical research, scientists say. As rare, they add, as finding mice with Mohawk-like hairstyles.
But both events happened in a lab at NYU Langone Medical Center, months after an international team of neuroscientists bred hundreds of mice with a suspect genetic mutation tied to autism spectrum disorders.
Almost all the grown mice, the NYU Langone team observed, had sideways,”overgroomed” hair with a highly stylized center hairline between their ears and hardly a tuft elsewhere. Mice typically groom each other’s hair.
Researchers say they knew instantly they were on to something, as the telltale overgrooming — a repetitive motor behavior — had been linked in other experiments in mice to the brain condition that prevents children from developing normal social, behavioral, cognitive, and motor skills. People with autism, the researchers point out, exhibit noticeably dysfunctional behaviors, such as withdrawal, and stereotypical, repetitive movements, including constant hand-flapping, or rocking.
Now and for what NYU Langone researchers believe to be the first time, an autistic motor behavior has been traced to specific biological pathways that are genetically determined.
The findings, says senior study investigator Gordon Fishell, PhD, the Julius Raynes Professor of Neuroscience and Physiology at NYU Langone, could with additional testing in humans lead to new treatments for some autism, assuming the pathways’ effects as seen in mice are reversible.
In the study, to be published in the journal Nature online May 25, researchers knocked out production in mice of a protein called Cntnap4. This protein had been found in earlier studies in specialized brain cells, known as interneurons, in people with a history of autism.
Researchers found that knocking out Cntnap4 affected two highly specialized chemical messengers in the brain, GABA and dopamine. Both are so-called neurotransmitters, chemical signals released from one nerve cell to the next to stimulate similar sensations throughout the body. GABA, short for gamma-aminobutyric acid, is the main inhibitory neurotransmitter in the brain. It not only helps control brain impulses, but also helps regulate muscle tone. Dopamine is a well-known hormonal stimulant, highly touted for producing soothing, pleasing sensations.
Among the researchers’ key findings was that in Mohawk-coiffed mice, reduced Cntnap4 production led to depressed GABA signaling and overstimulation with dopamine. Researchers say the lost protein had opposite effects on the neurotransmitters because GABA is fast acting and quickly released, so interfering with its action decreases signaling, while dopamine’s signaling is longer-acting, so impairing its action increases its release.
"Our study tells us that to design better tools for treating a disease like autism, you have to get to the underlying genetic roots of its dysfunctional behaviors, whether it is overgrooming in mice or repetitive motor behaviors in humans," says Dr. Fishell. "There have been many candidate genes implicated in contributing to autism, but animal and human studies to identify their action have so far not led to any therapies. Our research suggests that reversing the disease’s effects in signaling pathways like GABA and dopamine are potential treatment options."
The U.S. Centers for Disease Control and Prevention estimate that one in 68 American children under age 8 has some form of autism, with five times as many boys as girls suffering from the spectrum of disorders.
As part of their study, researchers performed dozens of genetic, behavioral, and neural tests with growing mice to isolate and pinpoint where Cntnap4 acted in their brains, and how it affected chemical signaling among specific interneuron brain cells, which help relay and filter chemical signals between neurons in localized areas of the brain.
They found that Cntnap4 in mature interneurons strengthened GABA signaling, but did not do so in younger interneurons. When researchers traced where Cntnap4 acted in immature brain cells, Dr. Fishell says tests showed that it stimulated “a big bolus of dopamine.”
As part of testing to confirm the hereditary link among Cntnap4, the two pathways, and grooming behaviors, researchers exposed young mice with normal levels of Cntnap4, who did not groom each other, to mature mice with and without Cntnap4. Only mature mice deficient in Cntnap4 preened the hairstyle on other mice. Further tests in young mice without Cntnap4 showed that other, mature mice with normal amounts of Cntnap4 largely let them be, without any particular grooming or hairstyle.
Dr. Fishell and his team plan further analyses of how GABA and dopamine production changes as brain cells mature, and precisely what cellular mechanisms are involved in autism. Their goal is to control and rebalance any biological systems that go awry, as a possible future therapy for the disease.

Mice with ‘mohawks’ help scientists link autism to 2 biological pathways in brain

"Aha" moments are rare in medical research, scientists say. As rare, they add, as finding mice with Mohawk-like hairstyles.

But both events happened in a lab at NYU Langone Medical Center, months after an international team of neuroscientists bred hundreds of mice with a suspect genetic mutation tied to autism spectrum disorders.

Almost all the grown mice, the NYU Langone team observed, had sideways,”overgroomed” hair with a highly stylized center hairline between their ears and hardly a tuft elsewhere. Mice typically groom each other’s hair.

Researchers say they knew instantly they were on to something, as the telltale overgrooming — a repetitive motor behavior — had been linked in other experiments in mice to the brain condition that prevents children from developing normal social, behavioral, cognitive, and motor skills. People with autism, the researchers point out, exhibit noticeably dysfunctional behaviors, such as withdrawal, and stereotypical, repetitive movements, including constant hand-flapping, or rocking.

Now and for what NYU Langone researchers believe to be the first time, an autistic motor behavior has been traced to specific biological pathways that are genetically determined.

The findings, says senior study investigator Gordon Fishell, PhD, the Julius Raynes Professor of Neuroscience and Physiology at NYU Langone, could with additional testing in humans lead to new treatments for some autism, assuming the pathways’ effects as seen in mice are reversible.

In the study, to be published in the journal Nature online May 25, researchers knocked out production in mice of a protein called Cntnap4. This protein had been found in earlier studies in specialized brain cells, known as interneurons, in people with a history of autism.

Researchers found that knocking out Cntnap4 affected two highly specialized chemical messengers in the brain, GABA and dopamine. Both are so-called neurotransmitters, chemical signals released from one nerve cell to the next to stimulate similar sensations throughout the body. GABA, short for gamma-aminobutyric acid, is the main inhibitory neurotransmitter in the brain. It not only helps control brain impulses, but also helps regulate muscle tone. Dopamine is a well-known hormonal stimulant, highly touted for producing soothing, pleasing sensations.

Among the researchers’ key findings was that in Mohawk-coiffed mice, reduced Cntnap4 production led to depressed GABA signaling and overstimulation with dopamine. Researchers say the lost protein had opposite effects on the neurotransmitters because GABA is fast acting and quickly released, so interfering with its action decreases signaling, while dopamine’s signaling is longer-acting, so impairing its action increases its release.

"Our study tells us that to design better tools for treating a disease like autism, you have to get to the underlying genetic roots of its dysfunctional behaviors, whether it is overgrooming in mice or repetitive motor behaviors in humans," says Dr. Fishell. "There have been many candidate genes implicated in contributing to autism, but animal and human studies to identify their action have so far not led to any therapies. Our research suggests that reversing the disease’s effects in signaling pathways like GABA and dopamine are potential treatment options."

The U.S. Centers for Disease Control and Prevention estimate that one in 68 American children under age 8 has some form of autism, with five times as many boys as girls suffering from the spectrum of disorders.

As part of their study, researchers performed dozens of genetic, behavioral, and neural tests with growing mice to isolate and pinpoint where Cntnap4 acted in their brains, and how it affected chemical signaling among specific interneuron brain cells, which help relay and filter chemical signals between neurons in localized areas of the brain.

They found that Cntnap4 in mature interneurons strengthened GABA signaling, but did not do so in younger interneurons. When researchers traced where Cntnap4 acted in immature brain cells, Dr. Fishell says tests showed that it stimulated “a big bolus of dopamine.”

As part of testing to confirm the hereditary link among Cntnap4, the two pathways, and grooming behaviors, researchers exposed young mice with normal levels of Cntnap4, who did not groom each other, to mature mice with and without Cntnap4. Only mature mice deficient in Cntnap4 preened the hairstyle on other mice. Further tests in young mice without Cntnap4 showed that other, mature mice with normal amounts of Cntnap4 largely let them be, without any particular grooming or hairstyle.

Dr. Fishell and his team plan further analyses of how GABA and dopamine production changes as brain cells mature, and precisely what cellular mechanisms are involved in autism. Their goal is to control and rebalance any biological systems that go awry, as a possible future therapy for the disease.

Filed under ASD autism dopamine Cntnap4 interneurons GABA neuroscience science

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Brain imaging reveals clues about chronic fatigue syndrome
A brain imaging study shows that patients with chronic fatigue syndrome may have reduced responses, compared with healthy controls, in a region of the brain connected with fatigue. The findings suggest that chronic fatigue syndrome is associated with changes in the brain involving brain circuits that regulate motor activity and motivation.
Compared with healthy controls, patients with chronic fatigue syndrome had less activation of the basal ganglia, as measured by fMRI (functional magnetic resonance imaging). This reduction of basal ganglia activity was also linked with the severity of fatigue symptoms.
According to the Centers for Disease Control and Prevention, chronic fatigue syndrome is a debilitating and complex disorder characterized by intense fatigue that is not improved by bed rest and that may be worsened by exercise or mental stress.
The results are scheduled for publication in the journal PLOS One.
"We chose the basal ganglia because they are primary targets of inflammation in the brain," says lead author Andrew Miller, MD. "Results from a number of previous studies suggest that increased inflammation may be a contributing factor to fatigue in CFS patients, and may even be the cause in some patients."
Miller is William P. Timmie professor of psychiatry and behavioral sciences at Emory University School of Medicine. The study was a collaboration among researchers at Emory University School of Medicine, the CDC’s Chronic Viral Diseases Branch, and the University of Modena and Reggio Emilia in Italy. The study was funded by the CDC.
The basal ganglia are structures deep within the brain, thought to be responsible for control of movements and responses to rewards as well as cognitive functions. Several neurological disorders involve dysfunction of the basal ganglia, including Parkinson’s disease and Huntington’s disease, for example.
In previous published studies by Emory researchers, people taking interferon alpha as a treatment for hepatitis C, which can induce severe fatigue, also show reduced activity in the basal ganglia. Interferon alpha is a protein naturally produced by the body, as part of the inflammatory response to viral infection. Inflammation has also been linked to fatigue in other groups such as breast cancer survivors.
"A number of previous studies have suggested that responses to viruses may underlie some cases of CFS," Miller says. "Our data supports the idea that the body’s immune response to viruses could be associated with fatigue by affecting the brain through inflammation. We are continuing to study how inflammation affects the basal ganglia and what effects that has on other brain regions and brain function. These future studies could help inform new treatments."
Treatment implications might include the potential utility of medications to alter the body’s immune response by blocking inflammation, or providing drugs that enhance basal ganglia function, he says.
The researchers compared 18 patients diagnosed with chronic fatigue syndrome with 41 healthy volunteers. The 18 patients were recruited [not referred] based on an initial telephone survey followed by extensive clinical evaluations. The clinical evaluations, which came in two phases, were completed by hundreds of Georgia residents. People with major depression or who were taking antidepressants were excluded from the imaging study, although those with anxiety disorders were not.
For the brain imaging portion of the study, participants were told they’d win a dollar if they correctly guessed whether a preselected card was red or black. After they made a guess, the color of the card was revealed, and at that point researchers measured blood flow to the basal ganglia.
The key measurement was: how big is the difference in activity between a win or a loss? Participants’ scores on a survey gauging their levels of fatigue were tied to the difference in basal ganglia activity between winning and losing. Those with the most fatigue had the smallest changes, especially in the right caudate and the right globus pallidus, both parts of the basal ganglia.
Ongoing studies at Emory are further investigating the impact of inflammation on the basal ganglia, including studies using anti-inflammatory treatments to reduce fatigue and loss of motivation in patients with depression and other disorders with inflammation including cancer.

Brain imaging reveals clues about chronic fatigue syndrome

A brain imaging study shows that patients with chronic fatigue syndrome may have reduced responses, compared with healthy controls, in a region of the brain connected with fatigue. The findings suggest that chronic fatigue syndrome is associated with changes in the brain involving brain circuits that regulate motor activity and motivation.

Compared with healthy controls, patients with chronic fatigue syndrome had less activation of the basal ganglia, as measured by fMRI (functional magnetic resonance imaging). This reduction of basal ganglia activity was also linked with the severity of fatigue symptoms.

According to the Centers for Disease Control and Prevention, chronic fatigue syndrome is a debilitating and complex disorder characterized by intense fatigue that is not improved by bed rest and that may be worsened by exercise or mental stress.

The results are scheduled for publication in the journal PLOS One.

"We chose the basal ganglia because they are primary targets of inflammation in the brain," says lead author Andrew Miller, MD. "Results from a number of previous studies suggest that increased inflammation may be a contributing factor to fatigue in CFS patients, and may even be the cause in some patients."

Miller is William P. Timmie professor of psychiatry and behavioral sciences at Emory University School of Medicine. The study was a collaboration among researchers at Emory University School of Medicine, the CDC’s Chronic Viral Diseases Branch, and the University of Modena and Reggio Emilia in Italy. The study was funded by the CDC.

The basal ganglia are structures deep within the brain, thought to be responsible for control of movements and responses to rewards as well as cognitive functions. Several neurological disorders involve dysfunction of the basal ganglia, including Parkinson’s disease and Huntington’s disease, for example.

In previous published studies by Emory researchers, people taking interferon alpha as a treatment for hepatitis C, which can induce severe fatigue, also show reduced activity in the basal ganglia. Interferon alpha is a protein naturally produced by the body, as part of the inflammatory response to viral infection. Inflammation has also been linked to fatigue in other groups such as breast cancer survivors.

"A number of previous studies have suggested that responses to viruses may underlie some cases of CFS," Miller says. "Our data supports the idea that the body’s immune response to viruses could be associated with fatigue by affecting the brain through inflammation. We are continuing to study how inflammation affects the basal ganglia and what effects that has on other brain regions and brain function. These future studies could help inform new treatments."

Treatment implications might include the potential utility of medications to alter the body’s immune response by blocking inflammation, or providing drugs that enhance basal ganglia function, he says.

The researchers compared 18 patients diagnosed with chronic fatigue syndrome with 41 healthy volunteers. The 18 patients were recruited [not referred] based on an initial telephone survey followed by extensive clinical evaluations. The clinical evaluations, which came in two phases, were completed by hundreds of Georgia residents. People with major depression or who were taking antidepressants were excluded from the imaging study, although those with anxiety disorders were not.

For the brain imaging portion of the study, participants were told they’d win a dollar if they correctly guessed whether a preselected card was red or black. After they made a guess, the color of the card was revealed, and at that point researchers measured blood flow to the basal ganglia.

The key measurement was: how big is the difference in activity between a win or a loss? Participants’ scores on a survey gauging their levels of fatigue were tied to the difference in basal ganglia activity between winning and losing. Those with the most fatigue had the smallest changes, especially in the right caudate and the right globus pallidus, both parts of the basal ganglia.

Ongoing studies at Emory are further investigating the impact of inflammation on the basal ganglia, including studies using anti-inflammatory treatments to reduce fatigue and loss of motivation in patients with depression and other disorders with inflammation including cancer.

Filed under chronic fatigue syndrome basal ganglia inflammation dopamine brain imaging neuroscience science

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