Tag: dopamine

Inside The Extrovert Brain

Dopamine Pathways. In the brain, dopamine plays an important role in the regulation of reward and movement. As part of the reward pathway, dopamine is manufactured in nerve cell bodies located within the ventral tegmental area (VTA) and is released in the nucleus accumbens and the prefrontal cortex. Its motor functions are linked to a separate pathway, with cell bodies in the substantia nigra that manufacture and release dopamine into the striatum (Image Source: WIkipedia)

Dopamine Pathways. In the brain, dopamine plays an important role in the regulation of reward and movement. As part of the reward pathway, dopamine is manufactured in nerve cell bodies located within the ventral tegmental area (VTA) and is released in the nucleus accumbens and the prefrontal cortex. Its motor functions are linked to a separate pathway, with cell bodies in the substantia nigra that manufacture and release dopamine into the striatum (Image Source: Wikipedia)

A recent study published in the journal Frontiers in Human Neuroscience focused on the neurotransmitter dopamine  – —the “pleasure chemical” – in the extroverted brain, finding that the reason extroverts seem to experience stronger positive emotions may be all about how their brains process the memory of rewards.

Reference:

Depue R.A. and Fu Y. Front. On the nature of extraversion: variation in conditioned contextual activation of dopamine-facilitated affective, cognitive, and motor processes. Hum. Neurosci. 13 June 2013

Weekly Neuroscience Update

Getting a grip—literally— by clenching your right fist before remembering information and your left when you want to remember it can boost your recall, according to the latest study. This strange trick may work because clenching your hands activates the side of the brain that handles the function— in right-handed people, for instance, the left side of the brain is primarily responsible for encoding information and the right for recalling memory. (If you are left-handed, the opposite applies).

Mathematicians from Queen Mary, University of London will bring researchers one-step closer to understanding how the structure of the brain relates to its function in two recently published studies.

Greater adherence to a Mediterranean diet (MeD) is associated with a lower likelihood of incident cognitive impairment (ICI), especially among those without diabetes, according to a study published in the April 30 issue of Neurology.

The widespread belief that dopamine regulates pleasure could go down in history with the latest research results on the role of this neurotransmitter. Researchers have proved that it regulates motivation, causing individuals to initiate and persevere to obtain something either positive or negative.

Supposedly ‘primitive’ reflexes may involve more sophisticated brain function than previously thought, according to researchers at Imperial College London.

The production of a certain kind of brain cell that had been considered an impediment to healing may actually be needed to staunch bleeding and promote repair after a stroke or head trauma, researchers at Duke Medicine report.

For any addiction, external  cues and stress can trigger  cravings that are hard to resist, and the latest research points to an area of  the brain that might be responsible  for sabotaging recovery.

Understanding Attention Deficit/Hyperactivity Disorder (ADHD) Part 2

In part two of my latest series on attention deficit/hyperactivity disorder (ADHD) we take a closer look at the nature of the disorder.

These positron emission tomography (PET) scans show that patients with ADHD had lower levels of dopamine transporters in the nucleus accumbens, a part of the brain’s reward center, than control subjects.

What is attention deficit/hyperactivity disorder?

Do you remember a classmate who just could not sit still or another who just sat quietly in the corner, day dreaming and looking out the window but when called on by the teacher did not know what was going on? Today both of these children might be diagnosed with ADHD. Indeed some still argue that there is no such thing as ADHD – that it is an artificially conceived diagnosis to aid the selling of prescription drugs and that in previous times a child with ‘ADHD’ was no more than considered to be no more than ‘bored’,’ restless’ or ‘giddy’.

Prognosis

ADHD was first described more than 100 years ago and its symptoms include excessively inattentive, hyperactive, or impulsive behaviours. For instance, children with ADHD find it more difficult to focus and to complete their schoolwork. ADHD affects up to eight in one hundred children and in over half the cases, it continues to persist into adulthood.Although most individuals with ADHD do not outgrow the disorder, their symptoms often change as they grow older, with less hyperactivity as adults. Problems with attention tend to continue into adulthood. There is no cure for ADHD at this time.

Possible causes

Recent brain imaging studies have shown a reduction in the levels of the neurotransmitters dopamine and noradrenaline in at least some people with the disorder. Because the nerve circuits in the prefrontal brain regions, which are normally involved in attention, require high levels of dopamine and noradrenaline stimulation, reduced levels of these two neurotransmitters could potentially lead to the weakened regulation of attention and behavior observed in ADHD .Altered brain activity also has been observed in particular nerve circuits connecting the cortex (outer part), striatum (deeper parts), and cerebellum (back of the neck), particularly in the right brain hemisphere with a delay in cortical development seen in some children with ADHD.
In part three of this series,  I will explain more what neuroscientists mean by ‘attention’, where it is found in the brain and how it is affected in ADHD.

Other Sources:
http://www.webmd.com/add-adhd/guide/

Part 1: Understanding ADHD and Learning Disability

 

Understanding ADHD and Learning Disability

Attention deficit/hyperactivity disorder (ADHD)and the learning disability which often accompanies it came up in conversation with students on the Family Support Course during my recent visit to the Bedford Row Family Project in Limerick. There was concern that ADHD was not being accurately diagnosed and that its treatment was inadequate at best.

In this first in a series of posts on ADHD Professor David Anderson explains how the current medical understanding of ADHD as merely a chemical imbalance in the levels of the two neurotransmitters dopamine and noradrenaline is not working and shows that by investigating a strain of hyperactive fruit fly (Drosophila), ADHD and learning disability involve two separate nerve pathways in the brain. These new findings may help scientists discover more selective treatments for these surprisingly commonplace disorders.

If you suffer from ADHD and/or a learning disability then this video may help you connect your personal experience with what the scientists are now discovering

Further reading for those interested in the scientific experiments:

  1. Lebestky et al. (2009). Neuron, 64 (4), 522-36 PMID: 19945394
  2. Wang L, & Anderson DJ (2010). Nature, 463 (7278), 227-31 PMID: 19966787

What we’re learning from 5,000 brains

Read Montague is interested in the human dopamine system — or, as he puts it in this illuminating talk from TEDGlobal 2012, that which makes us “chase sex, food and salt” and therefore survive.

Specifically, Montague and his team at the Roanoke Brain Study are interested in how dopamine and valuation systems work when two human beings interact with each other.

“We have a behavioral superpower in our brain and it at least in part involves dopamine,” says Montague in this talk. “We can deny any instinct we have for survival for an idea. No other species can do that.”

So how do we assign value to ideas, process the gestures of those around us, make complicated decisions, and create informed judgments about each other? Montague’s lab hopes to discover much more about how these processes work by “eavesdropping” on the brains of 5,000 to 6,000 participants all over the world as they play negotiation games. It’s fascinating research that could tell us more about our social nature. Because as Montague says, “You often don’t know who you are until you see yourself in interaction with people who are close to you, people who are enemies to you, and people who are agnostic to you.”

Source: TED blog

Your Brain On Cannabis: Part Three

Welcome to the final part of this three part series on the effects of cannabis on the brain, and today we look at marijuana as medicine.

There are several well-documented beneficial effects of marijuana including the amelioration of nausea and vomiting, stimulation of hunger in chemotherapy and AIDS patients, lowered intraocular eye pressure (shown to be effective for treating glaucoma), as well as general analgesic effects (pain reliever).

The first treatment to emerge from understanding cannabinoids is the drug rimonabant, recently approved in Europe to treat obesity and related metabolic conditions. The drug works by binding to receptors in the brain and body organs to block cannabinoid action. Studies have shown that an overactivated cannabinoid system in brain areas like the hypothalamus -which is involved in appetite increases food intake and fat accumulation. Rimonabant and similar compounds reduce cannabinoid overstimulation to help normalize appetite, body weight and fat, and also cholesterol levels. Drugs that decrease cannabinoid action also may cause anxiety or depression-side effects scientists are working to combat.

Research is underway to determine if rimonabant also will help smokers and heavy drinkers quit. Scientists believe that rimonabant could work in these conditions by reducing levels of the chemical dopamine in the brain’s motivation centers, which nicotine and other addictive drugs trigger.

In 2011, an oromucosal spray for Multiple Sclerosis patients became licensed for use as a medicine in Canada and parts of Europe, allowing it to be routinely prescribed by doctors. This drug reduces the pain, tremor, and muscle spasms associated with this disease.

Synthesized cannabinoids are also sold as prescription drugs, including Marinol (dronabinol) in the United States and Germany and Cesamet (nabilone) in Canada, Mexico, the United States and the United Kingdom. Canada, Spain, The Netherlands, Austria and fourteen states in the US have legalized some form of cannabis for medicinal use.

I regularly visit schools to explain how addictive drugs including cannabis affect the brain.

Click to arrange a speaking engagement.

For those interested in the topic of marijuana abuse more information can be found at: http://drugabuse.gov/ResearchReports/Marijuana/marijuana3.html


What is dopamine?

Dopamine is a neurotransmitter that helps control the brain’s reward and pleasure centers. Dopamine also helps regulate movement and emotional responses, and it enables us not only to see rewards, but to take action to move toward them.

Dopamine deficiency results in Parkinson’s Disease, and people with low dopamine activity may be more prone to addiction. Most abused drugs cause the release of dopamine and this is thought to contribute to their addictive properties.

This video describes some of the cognitive functions of dopamine in your brain.

What’s going on with Charlie Sheen?

Is Charlie Sheen suffering from bipolar disorder?

As actor Charlie Sheen’s bizarre media blitz continues, viewers are left to ponder if Sheen’s interviews are some kind of brilliant performance art or evidence of an epic meltdown, or some combination of the two. Or is his current behaviour evidence of a more worrying mental illness.

Some psychologists have stated that Charlie Sheen appears to have bipolar disorder. Dr. Drew Pinsky has said that Charlie Sheen appears to be having a “manic episode.”

Another psychologist says that Charlie Sheen is showing classic symptoms of bipolar disorder. “The symptom I see is the pressured speech.” he says. “[Sheen is] really pushing to get those words out; he’s really on a roll. He’s getting everything coming out pretty fast, almost faster than his brain can think and that’s very common with people who have bipolar disorder.” 1

What is bipolar disorder?

Over 300,000 people in Ireland suffer from depression, however a less common form of depression is manic depression also known as bipolar disorder which affects about 20,000 Irish people. Bipolar disorder is a mood disorder characterised by extreme lows with feelings of hopelessness and sadness followed by elated manic highs where in your mind anything becomes possible. 

Vicious cycles

These extremes of mood often follow each other in regular cycles that may be days, months or even years apart although on average there are twice as many episodes of depression then for mania. Like any other mental illness bipolar disorder is related to genetic background and personality type but can also be triggered by stressful events. However in a lot of cases bipolar disorder can arise ‘out of the blue’ when people’s lives’ are going quite well. 

Similarities to classic depression

The depressive symptoms experienced by people with bipolar disorder are similar to those people who experience classic depression.  One minute you are working away in your garden and the next you can be overtaken by profound feelings of despair – a sense of being totally worthless – that can take you down into the depths of depression. In this situation the mood is very low and daily life can become so overwhelming that it can be difficult to endure. As the feelings deepen – thoughts of suicide and a preoccupation with suicide often emerges. 

Manic depression

The German psychiatrist Emil Krapelin coined the term ‘manic depression’ after examining many patients with this condition back in the 1800’s. Even then Krapelin believed that this condition was caused by a specific abnormality in the brain. 

Where in the brain does depression occur?

Depression is associated with a disturbance in the prefrontal lobe of the brain – found just behind the eyes. This region of the brain is involved in judging things to be good or bad. It is also involved in social behaviour and interpreting social situations so it is not surprising that the low mood, reduced motivation and social withdrawal are key symptoms of depression. For this reason, people who are depressed often feel rejected or cut off from the world and blame themselves for wars in distant lands – even though they may have never visited that country. 

The role of amines in depression

Neuroscientists still don’t know for certain why people develop bipolar disorder but they do know that it is related to imbalances in brain chemicals called neurotransmitters which are involved in communication. However, research over the past 40 years has the confirmed that depression is associated with low levels of family of chemicals called amines. Amines are neurotransmitters that help nerve cells to stay in touch with each other. A lack of these amines particularly dopamine and serotonin which are carried by nerve pathways into the frontal lobe leads to a kind of starvation of nerve cells in the frontal lobe – giving rise to the symptoms of depression. 

Reserpine and depression

The link between low amine levels and depression was made when reserpine a drug to lower blood pressure also lowered brain amine levels and caused very profound depression. Also, addictive drugs such as cocaine, amphetamine and alcohol which inappropriately increase amine levels in the brain can trigger depression upon withdrawal. So the message is simple – in order to avoid depression you need healthy levels of these amines in our brain and you need healthy mental health habits to keep them there. 

Medication for depression

Over the past 25 years neuroscientists been working hard to develop drugs that can safely raise amine levels in the brain – the so-called antidepressant drugs – and better, more effective antidepressants come on the market every decade. 

The manic phase of bipolar disorder

In contrast to the depressive phase, the manic phase of bipolar disorder is the ‘polar’ opposite of depression. Feelings of boundless energy and that anything is possible are often felt. Many people are often creative in this phase.  The German composer Robert Schuman experienced bipolar disorder throughout his life. He completed four works in 1829 when in a depressed phase and twenty-five works a year later when in a manic phase. 

The secret of our success…

If bipolar disorder were due to a bad gene then why has it not been weeded out over the generations? One answer is that despite the truly awful cost to the life of the individual the gene for bipolar depression continues to exist because it confers an advantage on our species such as the creative insights leading to discoveries, inventions and exceptional performances in science, the arts, drama, music, sport and business – contributing to the great advances in our civilization – from which we all benefit. Ironically then, bipolar disorder may be the secret of our success as a species.  

…comes at a very high cost

Very tragically the rate of suicide in bipolar disorder is very high. The cycle of depression and mania lead the German composer Robert Schuman to an attempted suicide in 1854. Almost a quarter (22%) of people with this condition will commit suicide.  This is higher than that observed in schizophrenia. 

Recognizing the manic phase

In severe mania an individual will behave in an uncharacteristic way. They will become very talkative, loud, verbal, very expressive, extremely confident even uncharacteristically confident. Some people will start-up companies in this phase. They will go out and direct traffic, invest unwisely. They don’t see things as being limited by their circumstances or by their personal capacities. In the manic phase literally anything is possible! 

The manic phase can come on quickly or gradually. The person may not be fully aware what is happening to them. They may find themselves drinking more, wanting to be with people, going to pubs and nightclubs and dancing all night despite the fact that they may be too old for it. There is a tremendous pressure to ‘do things’ such as going out to dig the garden at 4am in the morning – for the stay-at-home types. 

The brain, stress and bipolar disorder

Whenever you encounter a stressful situation the pituitary gland in your brain sends a signal to your adrenal glands (just above your kidneys) to release cortisol which in turn gets your body ready for action. However blood cortisol levels are much higher than normal in depression and bipolar disorder causing a general state of high alert including early morning wakening which contributes to mental exhaustion.

Neuroscientists believe that the manic phase is an over activity of the dopamine and serotonin pathways in the frontal lobe.  In this way a dysfunction in the serotonin pathway in the brain has a ‘knock-on’ affect in the regulation the pituitary gland which in turn inappropriately over-activates the adrenals to release too much cortisol. However neuroscientists still don’t know for certain why people develop bipolar disorder.

Lithium and treatment of bipolar disorder

Mania is very resistant to treatment – benzodiazepines, major tranquilizers and antidepressants don’t work adequately. Fortunately there is lithium – an element found as a salt in soil and rocks and thus very cheap to make. Because it is element lithium cannot be patented (owned) by the drug industry. It was for this reason that lithium was largely ignored for years by the pharmaceutical industry. However, even in ancient times lithium was known to be a mild sedative. The mood stabilising effect of lithium was rediscovered by accident by an Australian psychiatrist John Cade in 1949 when working with guinea pigs. After ingesting lithium himself to ensure its safety in humans, Cade published an article “Lithium salts in the treatment of psychotic excitement” – which is still the number one most cited article in the Medical Journal of Australia. Lithium was eventually accepted as a treatment for mania in the 1970s.

Lithium – a truly life saving drug

Initially investigated as a treatment for gout, lithium has the effect of calming nerve cells. While lithium is the conventional treatment for the manic phase of bipolar disorder and reaches the brain within hours it can take up to six weeks to show an effect. Lithium is also very toxic particularly to the thyroid and kidneys. The required dosage 400–600 mg (15–20 mg per kg of body weight) is slightly less than the toxic level, requiring blood levels of lithium to be monitored closely during treatment. Within four to five days of stopping lithium a person can begin to get high again. Despite its limitations lithium is truly is a life saving drug – the only one to have an anti-suicide effect – allowing people to manage their moods and get on with their lives.  

The cup that cheers

Hundreds of soft drinks once included lithium salts or lithia water (naturally occurring mineral waters with higher lithium amounts). An early version of Coca Cola available in pharmacies’ soda fountains was called Lithia Coke and was a mixture of Coca Cola syrup and lithia water. The soft drink 7 Up, originally named “Bib-Label Lithiated Lemon-Lime Soda”, contained lithium citrate until it was reformulated in 1950. Lithia light beer was brewed at the West Bend Lithia Company in Wisconsin.

In 2009, Japanese researchers at Oita University reported that low levels of naturally-occurring lithium in drinking water supplies reduced suicide rates. A previous report had found similar data in the American state of Texas. In response, psychiatrist Peter Kramer raised the hypothetical possibility of adding lithium to drinking water.

A possible future treatment?

Research shows that manic depression seems to run in families so genetics also plays a role. Nobel Prize winner Paul Greengard of Rockefeller University, New York believes that a low-level of expression in a gene called P11 – which regulates serotonin levels in the brain – may underlie bipolar disorder. Gene therapy whereby healthy P11 genes are injected into the brain may be a future treatment.    

1 Source: kfor.com