Evolving causal belief

Photo by Flickr user evoo73. Click for sourceThere’s an interesting letter in this week’s edition of Nature from biologist Lewis Wolpert making the speculative but interesting claim that the development of causal belief may have been a key turning point in human evolution.

Wolpert is responding to a recent Nature essay critiquing the idea that closely related species will have evolved similar psychological processes, suggesting that it is shared selection pressures rather than genetic similarity that more greatly influences mental make up.

He responds by saying that we should focus on some of things that have uniquely evolved in humans rather than shared processes. He cites the ability to understand cause as a key example.

The feature that is peculiar to humans is their understanding about the causal interactions between physical objects (see, for example, L. Wolpert Six Impossible Things Before Breakfast; Faber, 2006). For example, children realize from an early age that one moving object can make another move on impact. It is this primitive concept of mechanics that is a crucial feature of causal belief, and that conferred an advantage in tool-making and the use of tools — which, in turn, drove human evolution.

Animals, by contrast, have very limited causal beliefs, although they can learn to carry out complex tasks. According to Michael Tomasello (The Cultural Origins of Human Cognition; Harvard Univ. Press, 1999), only human primates understand the causal and intentional relations that hold among external entities. Tomasello illustrates this point for non-human primates with the claim that even though they might watch the wind shaking a branch until its fruit falls, they would never shake the branch themselves to obtain the fruit. Some primates are, nevertheless, at the edge of having causal understanding.

Once causal belief evolved in relation to tools and language, it was inevitable that people would want to understand the causes of all the events that might affect their lives — such as illness, changes in climate and death itself. Once there was a concept of cause and effect, ignorance was no longer bliss, and this could have led to the development of religious beliefs.

Link to Wolpert’s letter in Nature.

All smoke and mirror neurons?

Photo by Flickr user Mike_in_Kboro. Click for sourceNew 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’.

Changes to psychiatrists’ diagnostic ‘bible’ hinted at

PsychCentral reports on the likely changes to appear in the DSM-V, the new version of the psychiatrist’s diagnostic manual, due out in 2012 and discussed in a recent presentation in last week’s American Psychiatric Association annual conference.

The most significant change proposed has to do with the inclusion of dimensional assessments for depression, anxiety, cognitive impairment and reality distortion that span across many major mental disorders. So a clinician might diagnose schizophrenia, but then also rate these four dimensions for the patient to characterize the schizophrenia in a more detailed and descriptive manner.

Despite the PR spin that “no limits” were placed on this revision of the DSM, the reality is that there will be very few significant changes from the existing edition of the DSM-IV. While virtually all disorders will be revised, the revisions will, for the most part, be incremental and small. Why? Because the APA recognizes that you can’t retrain 300,000 mental health professionals (not to mention the 500,000 general physicians) in the field to completely relearn their way of diagnosing common mental disorders such as depression, bipolar disorder, ADHD and schizophrenia. Changes are always incremental and tweak the existing system, nothing more.

The inclusion of dimensional ratings owes much to the role of psychometrics in the assessment of mental illness, but it remains to be seen how extensively this is implemented as it could just be a fancy label for sub-categories of degree (slight, moderate, severe etc) rather than the reliance on statistically sound measurements.

The post also mentions that there may be some moving of the diagnostic furniture with some additions and retractions but no major shakeups.

There’s more coverage on MedPage, but bear in mind that as we’re still three years away from publication so it’s worth bearing in mind that some of the final decisions have still to be made.

Link to PsychCentral post ‘Update: DSM-V Major Changes’.
Link to MedPage coverage.

Russian roulette in the medical literature

Photo by Flickr user bk1bennet. Click for sourceI’ve just discovered there’s a small medical literature on deaths by Russian roulette, where people put one bullet in a revolver, spin the chamber, put the gun to their head and pull the trigger.

A recent article from the The American Journal of Forensic Medicine and Pathology has a 10-year case review covering 24 deaths (wow) from the US state of Kentucky alone and serves as a summary of the research into this fate-tempting and most suicidal of games.

It’s a curious set of studies for which the most reliable finding is that people who die by Russian roulette are mostly young men who were drunk or had taken drugs.

On the more unusual side, one study found a link between participation in Russian roulette and “the types and number of tattoos and body piercing”.

The article also briefly describes a number of previous case reports from the literature, including this one which is remarkable for both mathematical and ultimately tragic reasons:

Playing a variation of traditional Russian roulette with his brother and 2 friends, the victim placed 5 live rounds in the cylinder, leaving one empty chamber, of a .357 Traus revolver. He spun the cylinder, put the gun to his right temple, and pulled the trigger. Postmortem blood toxicology revealed an ethanol level of 0.01% and the presence of diazepam and nordiazepam. The decedent had played Russian roulette on 2 occasions in the previous several weeks, each time placing only one live round in the cylinder.

Link to study on Russian roulette and risk-taking behaviour.
Link to DOI entry for same.

Freestyle Lehrer

Edge has an excellent interview with science writer Jonah Lehrer who riffs on consciousness, the joy of discovery, the importance of the marshmallows in psychology and how he fell in love with science.

It’s interesting because rarely do science writers get the opportunity to give their own opinions on the big questions in neuroscience, despite the fact that, as Lehrer mentions, they have a distinct way of looking at the field as a whole.

Writers have a massive influence on politics, economics, business and the arts, to the point where they are actively courted and coerced by those wanting to control the agenda, but there is much less of a tradition of writers influencing science outside the political sphere.

In fact, it’d be interesting to directly ask science writers for their own theories one day, but in the mean time here’s a rare opportunity to see one ‘in action’ on the big issues.

The questions I’m asking myself right now are on a couple different levels. For a long time there’s been this necessary drive towards reductionism; towards looking at the brain, these three pounds of gelatinous flesh, as nothing but a loop of kinase enzymes. You’re a trillion synaptic connections. Of course, that‚Äôs a necessary foundation for trying to understand the mind and the brain, simply trying to decode the wet stuff.

And that’s essential, and we’ve made astonishing progress thanks to the work of people like Eric Kandel, who has helped outline the chemistry behind memory and all these other fundamental mental processes. Yet now we’re beginning to know enough about the wet stuff, about these three pounds, to see that that’s at best only a partial glance, a glimpse of human nature; that we’re not just these brains in a vat, but these brains that interact with other brains and we are starting to realize that the fundamental approach we’ve taken to the mind and the brain, looking at it as this system of ingredients, chemical ingredients, enzymatic pathways, is actually profoundly limited.

The question now is, how do you then extrapolate it upwards? How do you take this organ, this piece of meat that runs on 10 watts of electricity, and how do you study it in its actual context, which is that it’s not a brain in a vat. It’s a brain interacting with other brains. How do you study things like social networks and human interactions?

Link to Jonah Lehrer interview on Edge.

Encephalon 71 welcomes new diners

The 71st edition of the Encephalon psychology and neuroscience writing carnival has just been served in the welcoming surroundings of the stylish Neuroanthropology blog.

A couple of my favourites include a podcast interview with neuropsychologist Chris Frith from the Brain Science Podcast blog, and a post on the development of early language from Babel’s Dawn.

There plenty more on the menu, so you should find something to suit every taste. Bon appétit!

Link to Encephalon 71.

A hostage to hallucination

Photo by Flickr user Meredith Farmer. Click for sourceI’ve just found a morbidly fascinating 1984 study on hallucinations in hostages and kidnap victims.

The paper is from the Journal of Nervous and Mental Disease and contains case studies of people who have been held captive by terrorists, kidnappers, rapists, robbers, enemy troops and, er… UFOs.

The reasoning behind including two ‘alien abductees’ was to compare hallucinations in verified versus unverified hostage situations. Cases of people who were hostages but did not hallucinate are also included.

The study found that one in four hostages had intense hallucinations, and these were invariably people who were in life-threatening situations. Isolation, visual deprivation, physical restraint, violence and death threats also seemed to contribute to the chance of having a hallucinatory experience.

Case 14

A 23-year-old member of a street gang was taken hostage by a rival gang. He was kept in a warehouse, blindfolded and tied to a chair, for 32 hours. He was severely beaten and forced to record ransom demands on a tape recorder. During captivity he became dissociated – “even when they were hitting on me I just tripped out, got out of my body… it was like I was high on Sherms (phencyclidine).” At one point he felt detached from his body and “floated” to the ceiling where he observed himself being beaten and burned with cigarettes but denied having any pain. He saw colorful geometric patterns in the air and flashes of past memories “like a dream, only I kept seeing devils and cops and monsters… nightmares I guess”. Eventually he was released when his gang paid the ransom.

Some of the case studies are a little disturbing, but it’s worth reading the paper in full if you can, or at least from the beginning of the case studies, as it’s a rarely discussed but remarkably striking aspect of human experience.

Link to article on ‘Hostage Hallucinations’.
Link to PubMed entry for same.