Weekly Neuroscience Update

Granule cells connect with other cells via long projections (dendrites). The actual junctions (synapses) are located on thorn-like protuberances called “spines”. Spines are shown in green in the computer reconstruction Credit DZNE/Michaela Müller.

Granule cells connect with other cells via long projections (dendrites). The actual junctions (synapses) are located on thorn-like protuberances called “spines”. Spines are shown in green in the computer reconstruction Credit DZNE/Michaela Müller.

New findings on the link between nerve cells at the interface to the hippocampus may have an influence on learning and memory.

People choosing between two or more equally positive outcomes experience paradoxical feelings of pleasure and anxiety, feelings associated with activity in different regions of the brain, according to research at the Princeton Neuroscience Institute at Princeton University.

Latest findings on how stress hormones promote the brain’s building of negative memories.

Researchers have studied the changes in the brain that are associated with impulsiveness, a personality trait that causes difficulties in inhibiting a response in the face of a stimulus and leads to unplanned actions without considering the negative consequences. These patterns can serve as an indicator for predicting the risk of behavioural problems.

People taking dopamine for Parkinson’s disease sometimes begin to generate a lot of artwork. New research differentiates their expressiveness from obsessive or impulsive tendencies.

Researchers have uncovered more than 100 genetic markers linked to developing schizophrenia.

A type of immune cell widely believed to exacerbate chronic adult brain diseases, such as Alzheimer’s disease and multiple sclerosis (MS), can actually protect the brain from traumatic brain injury (TBI) and may slow the progression of neurodegenerative diseases, according to research published in the online journal Nature Communications.

Weekly Neuroscience Update

3D-printed model of a neuron (credit: Yale University)

3D-printed model of a neuron (credit: Yale University)

A Yale neuroscientist  has created the first 3D-printed neuron.

Studies released today suggest promising new treatments for nicotine and heroin addiction, and further our understanding of pathological gambling and heroin abuse in those suffering chronic pain. This new knowledge, released at Neuroscience 2013, the annual meeting of the Society for Neuroscience (SFN) and the world’s largest source of emerging news about brain science and health, may one day lead to non-pharmaceutical interventions and therapies to treat addiction. Also presented at SFN, new studies revealing links between social status and specific brain structures and activity, particularly in the context of social stress.

A new study has found that people experiencing a depressive episode process information about themselves differently than people who are not depressed.

To flexibly deal with our ever-changing world, we need to learn from both the negative and positive consequences of our behaviour. In other words, from punishment and reward. Hanneke den Ouden from the Donders Institute in Nijmegen demonstrated that serotonin and dopamine related genes influence how we base our choices on past punishments or rewards. This influence depends on which gene variant you inherited from your parents. These results were published in Neuron on November 20.

Brain scans reveal that people with fibromyalgia are not as able to prepare for pain as healthy people, and they are less likely to respond to the promise of pain relief.

Scientists have used RNA interference (RNAi) technology to reveal dozens of genes which may represent new therapeutic targets for treating Parkinson’s disease. The findings also may be relevant to several diseases caused by damage to mitochondria, the biological power plants found in cells throughout the body.

Playing a fast-paced strategy video games can help the brain to become more agile and improve strategic thinking, according to new research.

While young children sleep, connections between the left and the right hemispheres of their brain strengthen, which may help brain functions mature, according to a new study by the University of Colorado Boulder.  And in another sleep study, a team of sleep researchers  has confirmed the mechanism that enables the brain to consolidate memory and found that a commonly prescribed sleep aid enhances the process. Those discoveries could lead to new sleep therapies that will improve memory for aging adults and those with dementia, Alzheimer’s and schizophrenia.

Why Parkinson’s Disease Has Robbed Linda Ronstadt Of Her Singing Voice

Singer Linda Rondstadt has recently been diagnosed with Parkinson's disease.

Singer Linda Rondstadt has recently been diagnosed with Parkinson’s disease.

The news that Linda Ronstadt has lost her powerful voice after a four-decade singing career as a result of Parkinson’s disease shocked not just the singer, but her many fans.

The 67-year-old Grammy-winning singer revealed last week that she struggled with symptoms of the disease for nearly eight years before getting her diagnosis just months ago. The neurological degenerative condition robs sufferers of their speech, mobility and their cognitive abilities.

During my career, I have spent almost 30 years investigating the effects of Parkinson’s disease on the brain and  I have seen great strides in our understanding and treatment of this illness.

What is Parkinson’s disease?

Over 4 million people worldwide suffer from Parkinson’s disease – a so-called hypokinetic disorder (hypo = lack of; kinetic = movement). Parkinson’s disease can be genetic but it can also be triggered by brain injury – as observed in boxers such as Muhammad Ali – and by environment – e.g. prolonged exposure to chemicals such as insecticides, weed killers and some drugs.  However in most cases Parkinson’s disease arises ‘out of the blue’ – i.e. idiopathic Parkinson’s disease. It is a progressive disease the symptoms start out small and get progressively worse but it is rarely fatal.

Three major symptoms

The disease is associated with three major symptoms (i) akinesia – an inability to start a movement – for instance when starting to brush your teeth, (ii) bradykinesia – an excessive braking or slowing of movement – when the brush strokes become shorter and eventually freeze and (iii) tremor – starting out as a trembling finger movements as if rolling a coin or pill – sometimes called ‘pill-rolling’ – which can progress to the whole body. With Parkinson’s disease one minute you are working away in the garden and the next you are literally stuck to the spot – totally unable to move. In these situations daily life can become a challenge that can be difficult to endure.

History

The disease is named after a British surgeon and political activist James Parkinson (1755-1824) who was born in London’s east end. In October 1794 he was questioned under oath before a council of state in connection with a plot to kill the King. He was exonerated but remained a strong advocate for the under-privileged. In 1817 he published An Essay on the Shaking Palsy reporting 6 cases. Although his publication was later considered the seminal work on the disease, it received little attention until a lot more cases came to light.

Where in the brain does Parkinson’s disease occur?

The Nobel Prize was awarded in 2000 to Professor Arvid Carlsson for his research over the past 50 years which confirmed that the ‘core defect’ in Parkinson’s disease is a loss of a chemical called dopamine in two tiny brain regions  – no bigger than a wart – called the substantia nigra. These two regions deep in the back of the brain – one on the left side and one on the right side – contain nerves that make a lot of dopamine and release it at their tips about 4 inches forward in the basal ganglia – located deep in the center of the brain where it helps to convert the intention/motivation needed to perform a movement into actual movement.

The core defect is a loss of dopamine

Dopamine belongs to a family of neurotransmitters called amines that help nerve cells to stay in touch with each other- sometimes called neurotransmitters. Dopamine acts like hydraulic oil which lubricates the basal ganglia nerve network involved in executing a movement. One only needed to go to watch Linda perform on stage at the height of her career to see dopamine in action as her brain effortlessly converted her thoughts and moods into the mesmerizing tonality, rhythm and range that made her so loved by a generation. In Parkinson’s disease the substantia nigra progressively dies, the supply of dopamine to the basal ganglia dries-up and like a car out of oil the engine seizes-up and movement grinds to a halt.

Trapped and disconnected

We need dopamine to survive. Dopamine allows us to talk, sing, socialize, improvise and take risks. When dopamine flows we don’t see things as being limited by circumstance. We have boundless energy and literally anything is possible!  Without dopamine we feel trapped and disconnected. It is not surprising therefore that mood can become low and depression is often associated with this illness.

Medication is expensive

Over the past 40 years neuroscientists been working hard to develop drugs that can safely raise dopamine levels in the Parkinsonian brain – the so-called antiparkinsonian drugs – and better, more effective treatments come on the market every decade.  Drug treatments are effective in managing symptoms but frequent changes are needed as the disease progresses. In the end many combinations of drugs at higher and higher doses may be needed and unpleasant side-effects may become an issue. Medication costs on average €100,000 per year.  Interestingly, the inexpensive anti-inflammatory drug ibuprofen has recently been shown to help stave off Parkinson’s disease possibly by protecting the substantia nigra but ibuprofen can itself produce unwanted side effects, including stomach bleeding.

Alternatives to drug-treatment?

deep  brain stimulation

Neuroscientists believe that the loss of the dopamine-rich nerves in the substantia nigra results is an over-activity of a ‘brake’ mechanism in the basal ganglia which in turn inappropriately shuts down movement.  Deep brain stimulation (DBS) takes advantage of our knowledge of this brain wiring by applying a small electric current into a target area called the subthalamic nucleus located deep within the basal ganglia to switch off the brake and free-up movement. It is an expensive and risky procedure but it can provide a new lease of life particularly to those patients for whom conventional drug treatment no longer seem to work.

The politics of brain research

Probably the most important lesson to be taken from Linda’s illness is that we need to open up a debate on how we as a society fund research into brain illness and highlight the realization that a deeper understanding of the brain IS the difference between a good and a bad quality of life for the sufferers of brain illnesses such as Parkinson’s disease.

I hope that Linda and her loved ones will take hope from the on-going research into Parkinson’s disease by teams of dedicated scientists worldwide.

Click on the link below to hear Professor Billy O’Connor talk about Parkinson’s disease on Mind Matters – a science programme on RTE radio.

http://www.podcastdirectory.com/episodes/mind-matters-on-parkinson-s-disease-3465171.html

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.