Category: Inside the Brain

The Boston Globe has a short but interesting article on cerebral folding – the science of why the brain is wrinkled up like a damp walnut.

The wrinkled surface of the brain folds into ‘ridges’ known as gyri and the ‘trenches’ known as sulci. This rippled landscape forms perhaps the most recognisable aspect of the human brain but we still don’t really know why we need this rather odd arrangement.

The standard answer “to fit more brain surface in the skull” really tells us nothing on its own as it’s not clear why the same material in the outer brain layers couldn’t be distributed differently.

Some answers are starting to emerge, however, not least from studies which look at differences in brain folding during the pre-birth growth phase and between people with different neurological conditions.

The article is full of fascinating findings from this research, not least of which is that the brain is smooth until quite late in pregnancy and only starts to fold in the last few months of development.

Premature babies seem to have this process partially disturbed for reasons that aren’t yet clear:

For example, because so much of the folding takes place during the latter weeks of fetal development, premature infants arrive with much of their cortical development yet to be completed. And the folding patterns of preemies relegated to the neonatal intensive care unit don’t match those of their counterparts who spend their full nine months in the womb. New research from Van Essen’s lab shows that even when preemies reach their originally forecasted due dates, their brains are not as large or as folded as those of full-term newborns.

“That means there’s something different in how those brains are organized and in the connections that have formed,’’ Grant said. Perhaps some extra environmental influence in the hospital is disrupting folding or preemies are missing out on some vital influence that their counterparts get in the uterus, though researchers haven’t yet narrowed down what these influences may be.

The article is brief but is packed full of eye-opening discoveries on brain folding. It’s one of those areas were we know so little but what we do know is quite compelling.

Link to Globe article ‘Unfolding the mysteries of the brain’.

According to press reports Michael Jackson will be buried without his brain because it is still ‘hardening’. Although this may seem unusual, the ‘hardening’ process is actually a standard part of any post-mortem examination where the brain is thought to be important in the cause of death, such as in suspected overdose.

It involves removing the brain from the skull and leaving it to soak in a diluted mixture of formaldehyde and water called formalin. This soaking process usually takes four weeks and the brain genuinely does harden.

A ‘fresh’ brain is a pinkish colour and has the consistency of jelly, gello or soft tofu meaning it is difficult to examine and the various internal structures are often hard to make out.

After soaking the brain, it has the consistency and colour of canned mushrooms making it easier to slice, examine and photograph. However, because the brain is so soft to start with, it can’t just be dropped in a tank of fixing solution, because it will deform under its own weight.

To solve the problem it is usually suspended upside down in a large bucket of formalin by a piece of string which is tied to the basilar artery.

After it has ‘hardened’ or ‘fixed’ it is sliced to look for clear damage to either the tissue or the arteries. Small sections can also be kept to examine under the microscope.

Because this part of the post-mortem takes several weeks preparation it is usually only carried out with the family’s permission as the body may need to be buried without it, or the burial delayed until the procedure is finished.

This also means that this form of post-mortem brain examination is usually only carried out where there is a feeling that examining the brain can help clarify the cause of death – which is what pathologists are often most concerned with.

In cases such as Michael Jackson’s, where the effects of drugs are suspected to play a part, pathologists will be looking for evidence of both sudden-onset and long-term brain damage. If they find it, they’ll be trying to work out how much it could have been caused by drug use and how much it contributed to the death.

Link to surprisingly good article in The Mirror.

Over the last couple of days, there’s been a great deal of coverage of three new studies on the genetics of schizophrenia. While the coverage has actually been pretty good, almost all the news stories make the same error when talking about the ‘genetic risk’ for the condition.

Twenty years ago, geneticists were searching for the ‘gene for schizophrenia’ until it became apparent that there was not going to be a single gene, or even a handful, found responsible for the mental illness.

It since became a mantra that the genetic risk for schizophrenia would be conferred by ‘many genes of small effect’. In other words, the cumulative effect of lots of genes that, on their own, would be quite benign.

Nature has just published three studies that use the only-recently-feasible technique of scanning the whole genome and has reported the first convincing positive evidence for the ‘many genes of small effect’ theory by finding that a whole bunch of genes, when considered together, account for about a third of the total difference in schizophrenia risk.

Interestingly, all three studies find that many of the genes lie in a <a href="region called the ‘major histocompatibility complex’ – a series of genes involved in the function of the immune system.

However, lots of the news reports, even from science publications give variations on the theme that ‘genetic factors account for 80 percent of the total risk of getting schizophrenia’.

This 80% figure (which can vary, some give 90%) is not an estimate of risk and shows a misunderstanding of estimated heritability taken from twin studies.

Luckily, I tackled exactly this issue in a column for July’s edition of The Psychologist:

Nature versus nurture is a lie. Music is not melody versus rhythm, wine is not grapes versus alcohol and we are not environment versus genes. We are their sum, their product and their expression. They dance together and we are their performance, but neither is an adversary. The art of understanding this elegant ballet is complex and arcane but you may never realise this from reading the quoted results of genetic studies, because the extent to which a trait is heritable, that is, accounted for by genetics, is usually expressed as a simple percentage.

If you search Google for the phrase “80 percent genetic”, you will discover hundreds of sources that claim that everything from schizophrenia, to height, to intelligence has been found to be four fifths ‘genetic’. Pick any other figure and you can find everyone from psychologists, to politicians, to journalists claiming that this or that is explained by genes to a given percentage. Geneticists know the subtly of this percentage and why these statements, usually lifted from the results of twin studies, are misleading, but clearly many others do not.

Imagine a mental illness is described as being 80% heritable. This is often taken to mean that four fifths of an individual’s risk is down to his or her genes, but this is not the case. What it means is that 80% of the variance in the measured illness was explained by genetic factors in the specific group that was studied. If this seems like a frivolous distinction, bear with me, because it is key in understanding heritability and it becomes crystal clear when tackled as an example.

Imagine that we could study a population where everybody lived in an identical environment. They did the same things everyday; they ate identical foods, had identical relationships and were stressed by identical events. Their lives were carbon copies of each other. A twin study would find that mental illness would be close to 100% heritable, because if the environment is fixed, any difference must be down to genetics. In fact, twin studies would find that everything is close to 100% heritable, for exactly the same reason. To flip our thought experiment on its head, if we only studied genetically identical clones, everything would be 0% heritable, because any difference must be down to the environment.

These figures do not necessarily tell us anything about the potential for a trait to be influenced by nature or nurture, because heritability is rarely an immutable and absolute fact about biology; it is an overall measure of how things are for that group, at that moment. In other words, the process of measuring the influence of genetics is, itself, subject to environmental factors. It captures the dance, not the dancers.

Thanks to Jon Sutton, editor of The Psychologist who has kindly agreed for me to publish my column on Mind Hacks as long as I include the following text:

“The Psychologist is sent free to all members of the British Psychological Society (you can join here), or you can subscribe as a non-member by emailing sarsta[at]bps.org.uk”

Link one two three to Nature genetics of schizophrenia studies.
Link to good write up from Science News, despite 80% genetic risk slip-up.

A 64 year old woman developed a phantom third arm after a stroke, but unusually, the patient was able to see and feel the illusory limb. A study just published online in the journal Annals of Neurology used brain scans to examine the patient. They established that the phantom sensations were accompanied by similar sorts of brain activity as you’d get from a real arm.

Unlike a classic ‘phantom limb‘, where a patient feels sensations as if they’re coming from the previously amputated body part, a ‘supernumerary phantom limb’ is where a phantom seems to appear additional to the already existing arm or leg.

The condition is rare but has been reported before and is known as the ‘supernumerary phantom limb’ in the medical literature. As we discussed last year, it is usually associated with strokes that affect the subcortical areas of the brain.

One of the reasons this new case is so interesting is because not only could the patient feel their additional limb, but they claimed to be able to see it and feel touches from it as well.

Tactile sensations in the SPL [supernumerary phantom limb] happened when she clenched her hand (she could then feel her phantom palm with her phantom fingers) and when she ‘touched’ certain parts of her body (in which case, the sensation was felt both in the phantom and the touched body part).

She could touch parts of her head, as well as her right shoulder. She claimed to be able to use the SPL to scratch an itch on her head (with an actual sense of relief). Moreover, she reported that the phantom could not penetrate solid obstacles (see supplementary materials for more details).

While a handful of cases of ‘visible’ supernumerary phantom limbs have been reported, this combination of seeing and feeling the touch of one is unique.

Importantly, the patient was not delusional – they didn’t believe they had an extra limb – they knew the sensations were unrealistic, but the experience was still there.

The limb was also not permanently felt – the patient could trigger it at will – and it appeared “pale,” “milk-white,” and “transparent.”

The researchers were keen to see if these sensations were reflected in the activity of the brain by using fMRI scans.

They found that ‘moving’ the phantom limb in front of the line of sight caused increased activation in the visual cortex of the brain.

Most strikingly, they found that when asked to ‘touch’ her cheek with the illusory hand, activity in brain areas representing cheek sensation increased.

There is always the chance that someone with very bizarre symptoms could be lying, but it is also the case that brain disturbance can cause all sort of confusions and distortions – so in some cases a patient’s description of what’s happening may not always be a reliable guide to exactly what they’re experiencing.

In this case, the brain imaging suggests that the ‘supernumerary phantom limb’ was genuinely being perceived as a visible additional arm and that its ‘touches’ were being processed by the sensory system in a similar way to touches from existing limbs.

Because the condition is so rare, and so conceptually bizarre, there is no good explanation of why it occurs except that it may be linked to the disturbance of our already established body and action ‘maps’ in the brain.

Apparently, there is more information about the case in supplementary material which can be found ‘in the online version of this article’, but the additional information doesn’t seem to be online. Ironically, the study seems to have a phantom of its own.

Link to study.
Link to PubMed entry for same.

Newsweek has a short but smart essay by neuroscientist Eric Kandel who riffs on some of the latest developments that have pushed forward our understanding of the neurobiology of mental disorder.

Kandel gives a description of one of the big biological discoveries from recent years, namely copy number variations, and explores what they might tell us about the development of psychiatric disorders:

One major advance has been the discovery that there is much more variability in the genome than had been anticipated, and that this takes the form of copy number variation (CNV). These are duplications or deletions of segments of a chromosome, often involving several or tens of genes, that enhance or depress the actions of specific genes. A well-known example of a CNV is the extra copy of chromosome 21 resulting in Down syndrome. It has recently been discovered that this type of variation is extremely common in everyone’s genome.

As he goes on to explain, CNVs have caused a lot of excitement in the world of mental illness research, not least because they’ve been found to occur in ‘out of the blue’ cases of schizophrenia – people without a family history of the disorder – suggesting that the disorder could be partially explained in some people by DNA ‘lesions’.

Some rare CNVs have been found to greatly increase the risk for schizophrenia, but unfortunately they don’t help explain the genetics of schizophrenia in general because there are many people with schizophrenia who don’t have these rare CNVs.

Nevertheless, this rare CNV finding may help us understand the neurobiology of the disorder by giving us clues based on how these unusual copy variations affect brain growth and protein expression.

Interestingly, those CNVs which have been found to increase the risk of schizophrenia also increase the risk for other disorders such as autism and intellectual disability (what the Americans call ‘mental retardation’) – suggesting that our diagnostic divisions between disorders may not be well supported by genetics.

Despite the title of the article, Kandel also highlights recent developments in psychotherapy, which have given us far the biggest advance in effective treatments for mental disorders in recent years.

Newsweek seem to have just released a whole collection of articles on biomedical sciences of which Kandel’s contribution is a part. But don’t miss a good article on ‘how science will enhance your brain’ and another piece on epigenetics.

Look on the right hand side for links to all the articles in the series.

Link to Newsweek on ‘A Biology of Mental Disorder’.
Link to Newsweek on ‘How Science Will Enhance Your Brain’.
Link to Newsweek piece on epigenetics.

There is now growing evidence that cannabis use causes a small but reliable increase in the chance of developing psychosis. Traditionally, this was explained by the drug increasing dopamine levels in the brain but a new study shortly to be published in NeuroImage suggests that the active ingredient in cannabis doesn’t effect this important neurotransmitter.

Despite some dissenting voices, disruption to the mesolimbic dopamine pathway is widely thought to be the key problem in the development of delusions, hallucinations and the other psychotic symptoms commonly diagnosed as schizophrenia.

This has led to the assumption that the small increased risk of psychosis reliably associated with cannabis use is due to the drug increasing dopamine levels in a deep brain structure called the striatum.

In itself, this is partly based on another assumption – the virtual mantra of recreational drug research that ‘all drugs of abuse increase dopamine levels in the reward system’ of which the striatum is a part.

This new study, led by neuroscientist Paul Stokes, tested dopamine levels by using a type of PET brain scan where participants are injected with a radioactive tracer that binds to free dopamine receptors. Higher dopamine levels will mean that there are less free dopamine receptors and, therefore, lower tracer levels.

Participants were tested twice, once when given placebo and once when given a dose of pure THC – one of the most important active ingredients in cannabis. The dose was designed to be roughly equivalent to the amount you might absorb from a single joint.

The researchers found no difference in dopamine levels between the THC and the sugar pill, even though the participants clearly reported the effects of the drug.

Although they only tested 13 participants, this is the largest study of its kind so far. These type of neurotransmitter tracer studies are know to produce conflicting results at times, so further experiments will be needed to be sure of the result.

But if it is the case that cannabis does not cause a significant increase in dopamine levels, this will mean our ideas about cannabis and psychosis will need a rethink.

It also shakes up the idea common idea that all recreational drugs are pleasurable because they affect the ‘dopamine reward system’.

Link to PubMed entry for the ‘in press’ study.

Forbes magazine has an excellent special issue that is rammed full of diverse and interesting articles on artificial intelligence.

It’s a large collection of short articles that covers everything from the mathematics of free will to the likelihood of there being a robot war in the future (see, it’s not just me).

There are a fair few speculative pieces, so those who like their transhumanists with a pinch of salt may have to be ready with the seasoning, but wide variety of articles means there should be something for everyone.

Each intends to introduce an idea rather than explore it in detail. I liked the pieces on whether AI can help fight terrorism and another on how the use of AI to explore theories of the mind has declined, and I’m still reading through the rest.

The only slight annoyance is that the series starts with the clich√© question “Can machines think?”

Perhaps the single most sensible response I ever read to this was a quote from a speech but the much missed Dutch computer scientist Edsger Dijkstra:

“The question of whether machines can think… is about as relevant as the question of whether submarines can swim.”

Link to Forbes ‘AI Report’.

I’ve just found this remarkable case study of a woman with an unpredictable form of ‘alien hand syndrome’ that was triggered when she had a seizure.

The syndrome, where you lose conscious control of one of your hands while it carries out unbidden actions, is normally associated with permanent damage to the brain, often in the frontal lobes, but this version only occurred when an epileptic seizure was in progress.

A 65-year-old right-handed Cuban woman experienced her first seizure while driving. She described an initial tonic posturing of her left foot with march throughout the leg.

This was followed by a counterclockwise truncal contortion and repetitive clonic movements of the foot, followed by her left hand viciously slapping her face, “as if it was fighting with me.”

Subsequent seizure semiology

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has been similar, although her nondominant left hand has refined its movements as to pretend it is applying lipstick.

Because of the embarrassing smearing of her preferred loud cherry-red lipstick, the patient has been forced to use more natural colors.

Link to PubMed entry for paper.

A new study has surveyed 17 astronauts to see what sort of headaches they experienced while on space missions. Headaches were much more frequent than on earth and didn’t fit a known type, suggesting that zero or micro gravity may be a specific trigger for a pounding head.

Below is the part of the article where the researchers discuss how the weightless conditions of space might affect the brain to cause the headache.

To describe headache, most astronauts used terms such as ‘exploding’ and/or ‘a heavy feeling’, confirming previous observations and suggesting a change in intracranial pressure. This is compatible with headache attributed to disorders of homeostasis, which can change during a state of microgravity. Certain haemodynamic [blood flow] changes might explain the occurrence of space headache. Alteration of cerebral blood flow and volume have been shown during exposure to microgravity.

The most striking change is the cephalad fluid shift, when body fluid redistributes and the blood volume in the upper body increases. The fluid shift towards the brain and probable brain oedema [swelling] could lead to an increase in intracranial pressure. Insofar as microgravity is also known to induce hypoxia [reduced oxygen supply to brain tissue], it also might be considered as a plausible trigger for space headache

Link to article.
Link to PubMed entry for same.
Link to write-up from BBC News.

I’ve just discovered there’s a form of neurotoxic honey, genuinely known as “mad honey“, created by bees taking nectar from the beautiful rhododendron ponticum flower, pictured on the right.

The nectar from these plants, prevalent around the Black Sea region of Turkey, occasionally contains grayanotoxins, a class of neurotoxin that interferes with the action potential (electrical signalling) of nerve cells by blocking sodium channels in the cell membranes. This leads to problems with the muscles, peripheral nerves, and the central nervous system.

Mad honey apparently causes “a sharp burning sensation in the throat” and poisoning leads to dizziness, weakness, excessive sweating, hypersalivation, nausea, vomiting and ‘pins and needles’ although severe intoxication can cause dangerous heart problems.

Luckily, most cases aren’t fatal and resolve after 24 hours.

Mad honey was known to the Romans, and was specifically discussed by Pliny the Elder.

Link to brief review article on mad honey.
Link to PubMed entry for same.

New Scientist has a tantalising snippet reporting on a shortly to be released and potentially important new study challenging the idea of ‘mirror neurons’.

Mirror neurons fire both when we perform an action and when we see someone else doing it. The theory is that by simulating action even when watching an act, the neurons allow us to recognise and understand other people’s actions and intentions…

However, Alfonso Caramazza at Harvard University and colleagues say their research suggests this theory is flawed.

Neurons that encounter repeated stimulus reduce their successive response, a process called adaptation. If mirror neurons existed in the activated part of the brain, reasoned Caramazza, adaptation should be triggered by both observation and performance.

To test the theory, his team asked 12 volunteers to watch videos of hand gestures and, when instructed, to mimic the action. However, fMRI scans of the participants’ brains showed that the neurons only adapted when gestures were observed then enacted, but not the other way around.

Caramazza says the finding overturns the core theory of mirror neurons that activation is a precursor to recognition and understanding of an action. If after executing an act, “you need to activate the same neurons to recognise the act, then those neurons should have adapted,” he says.

The study is to appear in the Proceedings of the National Academy of Sciences and apparently is embargoed so the full text is not yet available, although it should appear here when it is.

The announcement is interesting because using adaptation is a novel way of testing ‘mirror neurons’ and the lead researcher, Alfonso Caramazza, is known for a long series of influential neuropsychology studies.

He has a reputation for being a sober and considered scientist so it will be interesting to see if the final study is really the challenge to mirror neurons as it seems.

Although the hype has subsided a little, the years following the initial reports saw these now famous neurons being used to explain everything from language, to empathy, to why we love art.

We’re now in a period where we’re taking, if you’ll excuse the pun, a somewhat more reflective look at the topic and developing more nuanced theories about how this brain system functions.

UPDATE: Grabbed from the comments. Looks like this paper might have the potential to cause a ruckus. A comment from mirror neuron researcher Marco Iacoboni:

Caramazza‚Äôs paper is seriously flawed. The technique of fMRI adaptation seemed very promising ten years ago, but careful studies on its neurophysiological correlates have demonstrated that its findings are uninterpretable. Indeed, Caramazza‚Äôs manuscript has been around for many years and nobody wanted to publish it. Caramazza managed to publish with an old trick that only PNAS allows: he handed it personally to a friend of his. The paper is basically unrefereed (this is what it means ‚ÄòEdited by…‚Äô under its title).

Link to NewSci on ‘Role of mirror neurons may need a rethink’.

NPR has an interesting audio series on brain function, spiritual experience and the growing field of neurotheology. It’s takes a fairly broad brush approach and has audio, video, an interactive thingy, and plenty of supporting material.

You might get slightly annoyed at some of the section titles (‘The God Chemical’, ‘The God Spot’) but there are some great little audio vignettes in there where people describe their spiritual experiences, whether they’ve been caused by prayer or even psilocybin – the main active ingredient in magic mushrooms.

The project borders on the edge of being a bit hokey at times but it saved by the commentary and interviews with neuroscientists working in the area.

There’s also a good article in June’s Scientific American entitled ‘Why People Believe Invisible Agents Control the World’ which looks at the origin of belief in angels, demons, spirits and the like.

Link to NPR interactive brain / god thingy.
Link to ‘Why People Believe Invisible Agents Control the World’.

I just found this amazing case study of a female mountaineer who was struck by lighting while climbing the Latemar Peak in the Alps and subsequently experienced a series of unusual symptoms.

She was taken off the mountain by helicopter and was so agitated in hospital she had to be put under for three days. On wakening she was having some remarkably bizarre hallucinations.

On 3 September 2004, a 23-year-old healthy woman was hit by a “bolt from the blue” while climbing on a ridge at 2750 m shortly before reaching the Latemar Peak in the Alps from a southern direction. The accompanying climber was about 50 m from the casualty, and reported that at the time of the incident (about 15:00 Central European Time (CET)), the sky was clear and sunny. He heard cracking thunder and was thrown to the ground by a massive shock wave.

The patient was also thrown to the ground, lost consciousness for a few seconds and was confused afterwards. She had no vision, dazzled by a bright light. On arrival of the air rescue team, her Glasgow Coma Scale was 9. She was hospitalised and because of extreme agitation, set to a drug-induced coma for 3 days. The initial CT scan showed bilateral occipital oedema, but no intracerebral or subarachnoid haemorrhages or skull fractures…

In the evening, still awake and 6 h after extubation, strange phenomena occurred. These exclusively visual sensations consisted of unknown people, animals and objects acting in different scenes, like a movie. None of the persons or scenes was familiar to her and she was severely frightened by their occurrence. For example, an old lady was sitting on a ribbed radiator, then becoming thinner and thinner, and finally vanishing through the slots of the radiator.

Later, on her left side a cowboy riding on a horse came from the distance. As he approached her, he tried to shoot her, making her feel defenceless because she could not move or shout for help. In another scene, two male doctors, one fair and one dark haired, and a woman, all with strange metal glasses and unnatural brownish-red faces, were tanning in front of a sunbed, then having sexual intercourse and afterwards trying to draw blood from her.

These formed hallucinations, partially with delusional character, were in the whole visual field and constantly present for approximately 20 h. At the time of appearance, the patient was not sure whether they were real or unreal, but did not report them for fear that she might be considered insane.

Link to PubMed entry for case study.

Frontal Cortex has alerted me to an interesting NPR radio segment on the fact that taller people have longer nerves and so will have slight sensory lag in comparison to shorter people.

It prompted me to look up some of the research in the area and I found an eye-opening study looking at a range of factors that can effect nerve conduction.

The researchers found that, after controlling for sex, age and temperature (it turns out your nerves are quicker when you’re warm), there was a 0.27 m/s decrease in the conduction speed of one of the leg nerves (the sural nerve) for each additional centimetre in height.

This is interesting because it is not only a reduction in time because the same speed signal is travelling a longer distance, but it actually seems that nerve signals travel more slower through longer nerves as well, owing to the fact the nerves get thinner the longer they are.

The radio segment suggests that taller people don’t experience the world as any different, because our brains try to make everything seem ‘in sync’.

In fact, this is a problem for everyone, no matter how tall we are, because we know we can update our actions quicker than the sensory signals can reach the brain.

In one of the most popular theories that attempt to explain this it it thought that we have an internal simulation of our actions that we can use to make fast decisions which is updated as and when sensory information arrives.

However, I tried to find some studies on whether taller people actually have slower reaction times, but I couldn’t find any, so let me know if you do.

Link to NPR ‘The Secret Advantage Of Being Short’.
Link to study on nerve conduction factors.
Link to DOI entry for same.

I’ve just read an elegant study on the neuroscience of gambling that wonderfully illustrates why the dopamine equals pleasure myth, so often thrown around by the media, is too tired to be useful.

I have seen countless news reports that claim that some activity or other causes dopamine to be released; that dopamine is the ‘pleasure chemical’; and that it’s also released by ‘drugs’, ‘sex’, ‘gambling’ and ‘chocolate’ (a quartet I have named the four dopamen of the neurocalypse).

Normally, this breathless attempt to make something sound sexy is followed by a slightly sinister bit where they say that this dopamine activity is also likely to make it ‘addictive’.

Dopamine is involved in drug addiction, but the over-extended clich√© is drivel, not least because the dopamine neurons start firing in the nucleus accumbens when any reward is expected. Whether it be heroin, a glass of water when you’re thirsty, or your favourite book on calculus – if that’s what floats your boat.

And herein lies the subtlety. Our best evidence tells us that while the dopamine system has many functions, it’s not really a reward system – it’s most likely a reward expectancy system of some kind. Theories of exactly what form this takes differ in the details, but it certainly seems to be active when we’re expecting a reward, whether it actually turns up or not.

The study on gambling, led by neuroscientist Luke Clark, demonstrates that this is true even when the actual experience is unpleasant.

The research team looked at the activity differences in the dopamine-rich mesolimbic system in a gambling task – comparing wins, misses and near-misses. Near-misses were where the reels on a slot machine just missed the payout.

It turns out that near-misses activate almost exactly the same dopamine circuits as actual wins – but here’s the punchline – they were subjectively experienced as the most unpleasant outcome, even worse than total misses.

In other words, the dopamine system was firing like a rocket display but the experience was awful.

Interestingly, although near-misses were experienced as aversive they increased the desire to play the game but only when the person had some perception of control, by choosing what the ‘lucky’ picture would be.

Of course, like choosing ‘heads or tails’, it’s only an illusion of control because the outcome is random anyway.

But because of reward expectancy the dopamine system is most active when we think we can control the outcome and modify our strategy next time, even if that sense of control is completely false.

Link to full-text of study on near-misses and dopamine.
Link to good coverage of study from Quirks and Quarks.

I’ve just found a video of someone with alien hand syndrome – a condition which usually occurs after brain injury or stroke where the affected person loses conscious control over the hand and where it seems to move with a will of its own.

In this case, the video was uploaded by YouTube user frankenerin, who asked someone to video her when she was in intensive care after suffering a stroke and having brain surgery while her ‘alien hand’ was still present.

There’s a couple of things to notice in the video. The first is that the clinician asks the patient to do the actions for using scissors and brushing teeth. This is to check the problem is not a form of general ideomotor apraxia, where common action patterns are damaged.

She can do the actions with one hand but not the other, suggesting her strange movements are not due to global action planning problems.

The clinician then asks whether the patient recognises the arm as hers.

This may seem an odd question, but he’s checking for somatoparaphrenia, where patients can deny ownership of a paralysed or action-impaired limb, sometimes saying that it belongs to someone else.

As it turns out, the patient says she generally knows it is hers, but when it is draped across her body in a certain position and making involuntary movements she can think it is someone else’s limb. In other words, she seems to have fleeting somatoparaphrenia.

The video then shows the hand moving of its own accord and the patient having to use the other hand to keep it out of trouble.

Despite looking like she’s in pretty bad shape, frankenerin later posted a wonderful follow-up video where she is back on her feet and feeling fine, although discusses how she’s had to adjust her career aspirations owing to the longer-term effects of the brain injury.

Unfortunately, the Wikipedia page on alien hand syndrome, also known as anarchic hand syndrome, is dreadful, but there’s an excellent 2005 article from The Psychologist by neuropsychologist Sergio Della Sala that covers the neuropsychology of the condition and what it tells us about free will. You can read it online as a pdf.

Link to alien hand syndrome video.
pdf of The Psychologist on alien / anarchic hand.