June 2007 – Page 4

Nerve signals may be shock wave riders

Wired has a good break down of theory that says that nerve cells don’t work on electricity as we assume, but instead transmit signals using pressure waves, and crucially, this might explain how anaesthetics work.

The idea that nerve cells send their signals as pressure waves is not brand new. Known as the Soliton model, it was first published in 2005 by Drs Andrew Jackson and Thomas Heimburg and was thought a bit of a curiosity.

It challenges the model of nerve cell functioning that was developed by Alan Hodgkin and Andrew Huxley, both of whom won the Nobel prize for their work.

Their discovery was that nerve cells can be understood as electrical circuits and that the transmission of nerve signals or action potentials can be described using a simple elegant mathematical formula.

This formula describes how nerve cells work remarkably well and is still the basis of much modern neuroscience.

So suggesting that the Hodgkin-Huxley model is wrong is likely to piss a lot of people off, and that’s exactly what the Soliton model has done.

However, this new paper suggests it could explain how anaesthetics work, which is one of the mysteries of modern neuroscience.

It’s a totally left-field idea, but if it works out, it would be a revolution in both neuroscience and medicine.

Link to Wired article on application of the Soliton model to anaesethics.
Link to 2005 scientific paper on the Soliton model.

Uncanny valley – the movie

The Age has a brief article looking at how film makers are trying to avoid the ‘uncanny valley‘ – the phenomenon where artificially created characters seem more unnervingly odd as they are made more life-like.

The idea is that we’re so used to picking up the subtlies of human appearance that android-like figures seem cold and stilted whereas less life-like cartoons or animals can often seem more expressive and ‘warm’ because we aren’t distracted by their not-quite-right attempts at being human.

This is a concept developed by robotics researchers but is also important when film-makers are trying to make likeable characters that audiences will warm to.

The article has noted that film makers have spent a lot of time trying to develop computer software to simulate things like hair movement, in an attempt to improve realism.

It’s hard to say what exactly is off-putting about ‘artificial humans’ though, so it’s not easy to know what to focus on to improve their likeability.

This might be one area where significant advances in human-computer interaction might be driven by the film and entertainment industry.

Link to article ‘When fantasy is too close for comfort’.

The mind is a metaphor

Dr Brad Pasanek is a literature researcher at the University of Southern California who has created a database of metaphors of the mind used in 18th century English literature.

It allows you to search by everything from standard keywords to the politics of the author and has over 8,000 entries.

As illustrated by Douwe Draaisma’s excellent book Metaphors of Memory, our scientific understanding of the mind often uses metaphors of the latest technological developments.

It’s no accident that we now tend to understand the mind in computational terms, as an information processing system, whereas in past centuries it was thought to operate on the principles of pressures, fluids and vapours.

Pasanek also runs a blog that highlights some of the background and history to the more interesting examples.

Link to The Mind is a Metaphor database.
Link to The Mind is a Metaphor blog.

A window on the mind

BBC Radio 4 science programme Frontiers just had a special edition on using brain scans to read the mind.

There’s been various reports in the media about research studies that have been able to identify subjective mental states or intentions from patterns on brain scans, mainly reported as a sort of ‘mind reading’ technology.

While these are genuinely interesting studies, they’re really not at the stage of being able to ‘read’ anyone’s thoughts.

The first thing to ask yourself when you hear this sort of claim is ‘has the effect been shown to work on individuals, or only as an average over a group?’. The next is ‘what task was the effect demonstrated on?’ and finally think about how reliably the effect could be demonstrated.

For example, on a recent brain imaging study that attempted to predict intentions, the prediction was made for individuals, but only between one of two possible options and the best reliability was 71%.

In other words, this study found that for each individual, when looking back at the data, with a choice deliberately designed to be predictable, their choice could be worked out before they made it about two-thirds of the time.

It’s hardly likely to concern anyone worried about the privacy of their thoughts.

It is a start though, and the implications of how the technology might be used as it becomes more accurate are certainly thought provoking.

The special edition of Frontiers talks to some of the researchers involved in this work and tackles the ethics of the technology.

Link to Frontiers on ‘Mind-reading’ (with audio).

Legal drug paraphenalia

Wired magazine has a slide show of the ~~bribes~~ promotional gifts given out at last month’s American Psychiatric Association by pharmaceutical companies trying to get doctors to prescribe their drugs.

It’s all fairly tacky stuff but they’re expensive enough to be motivating. These sorts of things are handed out willy-nilly by drugs reps and your local doctor’s office is likely to be awash with these sort of semi-useful adverts.

At conferences, to get the more expensive gifts you usually have to complete a short quiz, which in reality is a push poll designed to make the key marketing points more memorable.

They tend to ask questions like:

In a 2003 research study [conducted by our company] of over 2,000 people, which drug was found to be most effective for condition X?

Was it:
a) our new drug Fixitall^TM
b) ye olde elixir of quicksilver
c) competitor’s drug [which incidentally, just had bad press]

In reality though, these sorts of promotions are really the tip of the iceberg. What you don’t get from the slide show, is that possibly the majority of people at the conference will have had their trip funded by drug companies, probably with dinners, cocktail parties and excursions thrown in.

Those who don’t, end up staying in cheap hotels, miles from the conference, in the seedy parts of town, because either they have to pay the whole trip themselves or their departments will only give modest amounts as it is assumed you can just get drug company money.

You can see why choosing to remain as uninfluenced as possible by drug company promotion is less attractive for some.

Of course, most clinicians argue that these sorts of things don’t influence them, but we know from exactly the same type of research that clinical science is based on that it has a strong and significant effect on attitudes and clinical practice.

What’s more, patients look upon these gifts much less favourably than clinicians do.

If you want to know more about the effects of drug company promotion and the bias in the advertising material, have a look at No Free Lunch.

As an aside, if there is a big psychiatric conference in town, go to the less glamorous area of the city, and you’ll find groups of researchers having a much better time. One of the disadvantages of attending the corporate events is attendees are expected to behave like the Queen at a garden party, so no-one “upsets the funders”. Very dull indeed.

Link to Wired article ‘Prescribe Me!’ (via BB).
Link to No Free Lunch campaign.

Neuro-war-on-terror-tainment

Lie Lab is a three-part TV series where they use the not-very-accurate brain scan lie detection method to test high profile people who have been accused of lying.

The programme quotes a 90% accuracy for fMRI lie detection, but this is a best estimate and has been found in group studies, in lab conditions, where the lies are relatively benign – such as saying you haven’t seen an image when you’ve been shown it earlier.

It’s not clear how well they detect highly motivated lies. Also, it seems that the brain scans are better at detecting lies than truths.

This is important, because you could get a 100% lie detection rate by classifying everything as a lie. Being able to adequately separate truth and lies is the key to accuracy.

The first episode tested two ex-Guantanamo bay detainees accused of being terrorists but eventually release without charge, the second tested a woman convicted of poisoning her daughter with salt who protests her innocence.

Needless to say, the results are largely inconclusive.

If the technology were any better, I’d write in and see if they can get Tony Blair for the grand finale.

The best thing about the programme is Prof Sean Spence, who’s done some of the key research studies on the neuroscience of lying and fMRI lie detection, and does his best to point out the ambiguity of the whole process.

UPDATE: Thanks to Deception Blog for pointing out that the series is available over the web for viewers in the UK or Eire via Channel 4’s on demand service. It’s on some private bittorrent trackers but I’ve not seen it on any publice ones yet. Keep a look out.

Link to Lie Lab website.
Link to Spence’s research papers (most of which are open-access).

2007-06-08 Spike activity

Quick links from the past week in mind and brain news:

A Polish man wakes up from a 19 year ‘coma’ and is remarkably functional (with video).

New Scientist reports that folic acid could protect against strokes.

From last year’s NeuroFest: A puppet show about autism called ‘The Boy Who Wanted to be a Robot’ is available on YouTube – part 1 and part 2.

The Mouse Trap has an insightful discussion on the psychology and neuroscience of imagination.

Advert for the London 2012 Olympics triggers seizures in some people with epilepsy. No word on the headaches caused by the logo.

Neuroscience video blog Channel N has found some vintage footage of neuroimaging experiments.

Research covered by New Scientist suggests that forgetfulness is a tool of the brain. Also see the case of Solomon Shereshevskii, a man studied by A.R. Luria, who had a problem with not being able to forget.

The Neurophilosopher finds some wonderful antique brain illustrations.

Brain injuries raise risk of Alzheimer’s disease, reports New Scientist.

CNN report on advances in neuroprothetics: Surfing the web with nothing but brainwaves.

The US Military are working on a humanoid battlefield robot to rescue fallen soldiers.

Providentia notes that the American Psychological Association are to review gay conversion therapy policy.

Furious Seasons notes Eli Lilly’s sudden interest in funding a charity who train dogs to help depressed people since they’ve released an anti-depressant for canines.

In other animal news: Cognitive Daily find previously suppressed evidence of Pavlov’s cat.

Know blood, know the brain

The Journal of Cerebral Blood Flow and Metabolism publishes cutting edge scientific research on brain scanning and blood flow, and it’s just put a collection of some of the key papers from the last few years online, for free.

It is particularly important that neuroscientists understand blood flow because this is what PET and fMRI, the two most popular forms of brain scanning, rely on to investigate brain activity.

Broadly speaking, both attempt to estimate which parts of the brain are most active by measuring which areas of the brain have the most blood going to them.

Despite the fact that brain scans look like a map of activity, the link between blood flow and the work done by neurons is still not fully understood.

For example, in fMRI, there seems to be a delay from when neuron activity occurs, to when the blood flow responds. A 2003 study [pdf] found that this delay was about two seconds long and was slower to return to normal the older you get.

While two seconds might seem a short amount of time, in brain time, it’s an age, as scientists are usually trying to understand changes that occur on the millisecond level.

Also, it’s not clear how closely the changes in blood flow reflect the quality and extent of neuron activity, because blood needs to move around the brain for many different reasons.

Therefore, an important goal in neuroscience is to try and solve these questions, to improve how we understand brain function from brain scans.

The online collection has articles that describe some of the most important research in this area from the last few years.

The papers are technical and in-depth, but even if you aren’t a neuroscientist, click on a few and just get a feel for what’s involved.

At the very least, the images can be truly beautiful.

Link to MRI and PET imaging collection (via BrainWaves).

Learning field sense

Wired has an article on ‘field sense’ – a sportsman’s ability to infer seemingly unknowable information from subtle perceptual cues.

This means that some sportsman appear to have a ‘sixth sense’ of where players are on the field, or can work out where a ball is likely to go before it is struck.

This tends to be present in pro-sportsman and previously, it was just thought to be something you’re born with. An advantage that makes some people more likely to rise to the top.

Wired magazine covers recent research in sports psychology suggesting it’s actually something that it learnt, and might well be teachable.

What happened in that fraction of a second? A lot, Farrow reasoned. Up to a point, he theorized, the direction of a serve was fundamentally unpredictable: Whatever clues existed weren’t ones that an opposing player could discern. By the time the ball had been hit, on the other hand, even a novice could make a plausible guess at its trajectory. What separated the pros from everyone else was the ability to pull directional information out of the early stages of a swing and therefore to predict a split second earlier where to head. This fraction of time is game- changing. A serve going 120 miles per hour takes approximately a third of a second to travel the 60 feet from baseline to service line. This means that an expert, who doesn’t have to wait until contact, has twice as long to move, plant his feet, and swing.

This discovery fit with something Farrow and other tennis researchers had already suspected: Reflex speed is not the key factor in returning a serve. “People have tested casual players and experts, and their reaction times are essentially the same,” Farrow says. The fact that Roger Federer can drill back a 140-mile-per-hour serve is partly a matter of muscle control. But it’s also about processing subtle visual cues to predict where the ball will go and get to the right spot.

Link to article ‘Wayne Gretzky-Style ‘Field Sense’ May Be Teachable’.

Dissolved and synthetic space

Developing Intelligence has an interesting look at a brain-injured patient from the medical literature who can identify objects, but can’t locate them.

RM suffered two strokes, damaging both sides of his occipito-parietal cortex (see the image above). This region of the brain is known to be important for spatial computations; this pattern of damage will often result in Balint’s Syndrome, characterized by three primary problems: the inability to perceive more than one object at a time (simultagnosia), the inability to reach towards objects that are being focused on (optic apraxia), and severe problems in changing which object the eyes are focused on (optic ataxia). Such patients are essentially blind outside the focus of their attention, and cannot locate, reach for, or track the spatial movements even of items that are within their focus of attention. In some ways, this represents the complete dissolution of spatial awareness; Robertson quotes a description of Balint’s “as if there is no there, there.”

The article suggests that the brain damage may have a caused a problem in ‘visual binding’.

The ‘binding problem‘ is the question about how the brain can process different aspects of an experience in different parts, but we still get an impression of a single combined perception.

For example, we know that colour is largely processed in an area of the visual cortex called ‘V4’ and motion processed in an area called ‘V5’, yet unless we suffer brain damage, we just experience a moving coloured object as a single experience.

Somehow, these different processes are combined into our conscious experience. It’s still a mystery, but patients like the one discussed in the Developing Intelligence article are giving us important insights into how the brain does the job, by seeing how it breaks down after injury.

The article also makes the interesting suggestion that while Balint’s syndrome and similar disorders might be the visual binding system not working properly, synaesthesia, where the senses are combined, might be visual binding working too hard.

Chris goes on to explore this idea in more detail, in a further article that looks at the research on visual binding in people with synaesthesia.

Link to DevIntel article ‘Dissolved Space: The Strange Case of Patient RM’.
Link to DevIntel article ‘Synthetic Space: Binding Errors In Synesthesia’.

Neurosurgical removal of knife in head

The picture is a man with a knife blade embedded in his head. It’s from a case report in the Croatian Medical Journal by a group of neurosurgeons who reported how it happened, and how they safely removed it.

The man was stabbed in the head by his daughter, who’s ominously described only as a ‘drug addict’ in the case report.

The blade penetrated 8cms into his skull but he was conscious on admission to hospital, he remembered the event, and had not fainted during or after the assault.

The surgical team used a grinder to remove the handle from the knife and CT scanned the patient’s head, and found the blade was at the very edge of the brain.

The neurosurgeons removed the knife, and the man recovered with no brain injury and no damage to the facial nerve.

pdf of full-text paper.

Child Ritalin use doubles after divorce

A study just published in the Canadian Medical Association Journal reports that children are twice as likely to be prescribed Ritalin after their parents have divorced.

Ritalin is the trade name for the amphetamine-like drug methylphenidate. It is typically prescribed for ADHD, a diagnosis which describes problems with staying focused, impulsiveness and / or hyperactivity.

Drug companies and some charities have invested a lot in selling the idea that ADHD is a purely neurological disorder and that the child’s family life has little to do with it.

This study suggests that this isn’t the case, and that the child’s environment and relationships, in combination with possible genetic and neurological differences, have a significant effect on their behaviour.

Actually, this won’t be news to most clinicians, who know that relationships and the environment have an effect even on conditions known to have a clear and defined neurological basis. For example, loneliness is known to contribute to the risk for Alzheimer’s disease.

In a sense, all psychological problems are problems with the brain, because the brain and the mind are just different ways of describing the same thing, and the environment has its effect through our neurons.

But this doesn’t mean it is possible to explain all human behaviour on only one level, and doing so will only give you part of the picture.

This study provides evidence that child behavioural problems are not best understood as neurological problems only, or that Ritalin is being used inappropriately to manage the behaviour of distressed children. Most probably, it’s a bit of both.

To be fair, this isn’t the only interpretation. The researcher notes that the known genetic component of ADHD could mean that the parents of children with behavioural share similar traits and so might be more likely to divorce because of this. It would be surprising if this accounted for the whole effect though.

People often use psychiatric diagnoses as if they’re explanations when really they’re nothing more than descriptions. The idea is that science will ‘fill in the gaps’ and explain how these differences occur.

The trouble is, the behaviour described by an ADHD diagnosis could occur because of genetic influences on brain development, because divorce is causing emotional distress, because the child is being bullied, or for any number of other reasons.

Ritalin is likely to help regardless of what is causing the child to be disturbed, because it helps the child focus by boosting attention.

The question is, should children be prescribed drugs because they are distressed by a divorce? There’s no definite answer in every case as each child and each situation is different.

But perhaps we should be concerned that children are likely being prescribed psychiatric drugs as a ‘quick fix’ for emotional distress and behaviour problems when research shows that parent training programmes are safe and effective.

Link to full-text scientific paper.
Link to write-up from Yahoo! News.

Encephalon 24 is released

The 24th edition of psychology and neuroscience writing carnival Encephalon has just been published at psychology blog The Phineas Gage Fan Club.

A couple of my favourites include a post on deep brain electrode recordings from the human nucleus accumbens and a post on a psychological sex differences study run on 200,000 participants (wow).

For more articles, on everything from law to neural information storage, follow the link below for the full edition.

Link to Encephalon 24.

Innate kindness and the moral brain

The Washington Post published an interesting article last week on research suggesting that human traits like generosity and altruism may be innate.

It describes a number of experiments which are tackling the relatively new field of ‘moral neuroscience’, which aims to understand how the brain is involved in moral decision-making.

What is interesting is that some of the brain areas found to be associated with this form of reasoning are those thought to be quite ‘old’ in evolutionary terms.

In one 2004 brain-imaging experiment [pdf], Greene asked volunteers to imagine that they were hiding in a cellar of a village as enemy soldiers came looking to kill all the inhabitants. If a baby was crying in the cellar, Greene asked, was it right to smother the child to keep the soldiers from discovering the cellar and killing everyone?

The reason people are slow to answer such an awful question, the study indicated, is that emotion-linked circuits automatically signaling that killing a baby is wrong clash with areas of the brain that involve cooler aspects of cognition. One brain region activated when people process such difficult choices is the inferior parietal lobe, which has been shown to be active in more impersonal decision-making. This part of the brain, in essence, was “arguing” with brain networks that reacted with visceral horror.

Such studies point to a pattern, Greene said, showing “competing forces that may have come online at different points in our evolutionary history. A basic emotional response is probably much older than the ability to evaluate costs and benefits.”

Link to Washington Post article.
pdf of paper mentioned in excerpt.

Insecurity service

Despair Inc has this fantastic parody of the t-shirts worn by private security firms at concerts, gigs and public events. So now you can wear the t-shirt and advertise yourself as a member of the insecurity team.

The company makes some fantastic parodies of corporate motivational merchandise, including a great range of demotivating posters.

Link to Despair Inc’s ‘Insecuritee’.

The rewards of being female

A recently published study has found that females show greater brain activation to uncertain rewards during the most fertile stage of the menstrual cycle, perhaps explaining why women dress more attractively and have altered sexual preferences during this time.

The dopamine system is known to be involved in reward processing, and one of the current theories is that it is particularly involved in reward prediction – that is, it signals when we might expect to find something gratifying.

The key female sex hormone estrogen is known to alter dopamine function, so it was thought that females might show changes in how they experience rewards when estrogen levels fluctuate during the menstrual cycle.

The most direct dopamine-related rewards are drugs like cocaine and amphetamine, and studies have found that the same dose feels stronger during the fertile follicular phase of the cycle.

Research, largely conducted with straight women, has found that females dress more attractively during this phase and have altered sexual preferences so that they experience more masculine looking, assertive males as more attractive.

This new study by Dr Jean-Claude Dreher and colleagues fMRI brain-scanned men and women during a gambling task, and looked at between-sex differences and within-cycle differences in brain activity.

They found that women have a greater response to rewards than men in the amygdala and hippocampus, both key emotion areas.

They also found that during the most fertile follicular phase of the menstrual cycle, women show more activity when predicting rewards, particularly in the amygdala and another key emotion and reward area, the orbitofrontal cortex.

When the reward was delivered (a win in the gambling task), women showed stronger response in a number of reward-related areas during the fertile phase, including the striatum, a dopamine-rich deep brain area.

It seems that the hormone cycle makes brain areas related to the prediction and experience of rewards become more active when women are more fertile. This might explain why the menstrual cycle can alter women’s sexual preferences and behaviour.

If you want more details of the study, the full paper is available at the link below.

Link to PubMed entry for the scientific paper.
pdf of full-text scientific paper.