Encoding memory: from a free issue of SciAm

To celebrate the launch of a redesign, Scientific American have made the July edition freely available online as a pdf file. The cover story examines the search for how the brain encodes memories.

The issue is only available online until the end of June (one more week!) so you’ll need to be quick, but it’s a copy of the entire issue.

On a related note, the June 25th podcast is on the neurology of boxing-related brain damage.

pdf of July 2007 Scientific American (via Neurophilosopher).
Link to July edition table of contents.

Oldest children have highest IQ: a family effect?

Science has just published a study of almost a quarter-of-million people providing strong evidence that oldest children have slightly higher IQs, and, most interestingly, the evidence suggests that this isn’t a biological effect – it’s likely to do with family environment and upbringing.

In fact, first-born children are known to have a number of psychological differences. For example, they are less likely to be gay, show differences in autistic-like traits, and are typically less severely affected by schizophrenia if it occurs.

These differences have often been explained by a theory that argues that the mother adapts her immune system during the first pregnancy and it might not be fully attuned to later children and this might affect the brain development of subsequent children.

In order to test this idea the Science study looked at the records of almost 250,000 Norwegian army recruits, all of which have routine IQ tests and full medical and family histories.

It turned out, as has been found many times before, that first-born children had higher IQs by about 3 points on average.

Crucially, it also turned out that some second-born children who had an older sibling who had died young also had higher IQs.

In other words, although they were second-born biologically, they were brought up as the oldest child after their sibling passed away.

Being brought up as the oldest child seems to be the crucial factor: family-rank, not birth order affects IQ. This suggests that the immune system theory is unlikely to explain this effect.

This has generated a great deal of discussion and many parents are interested in whether they can provide the ‘first child advantage’ to their younger children as well.

The New York Times featured the study and just published a follow-up article discussing the role of family-dynamics in the development of intelligence after all the interest it generated.

Some psychologists are suggesting that the effect might be because older children get the chance to coach the junior family members which may help them consolidate knowledge and provide practice in manipulating information.

It’s also interesting that a recent study on birth-order in Thai medical students found exactly the reverse pattern. Younger siblings were found to be more intelligent and have more positive personality factors.

All of these studies suggest that culture and environment are crucial factors during childhood, both for mental and emotional development.

Link to abstract of Science study (thanks Laurie!).
Link to NYT write-up.
Link to NYT on intelligence and family dynamics.

Mind the gap: science and the insanity defence

Reason Magazine has an excellent article on why our knowledge about the psychology and neuroscience of mental illness doesn’t really help when trying argue for or against the insanity defence in court.

The insanity defence concerns whether a person accused of a crime should be considered legally responsible.

Some of the first legal criteria for judging someone ‘not guilt by reason of insanity’ are the M’Naghten Rules created after Daniel M’Naghten tried to assassinate the British Prime Minister Robert Peel in 1843.

He ended up killing Peel’s secretary, but when caught was found to be suffering from paranoid delusions and it was judged that his crime was motivated by his unsound mind and he didn’t understand the ‘nature and quality’ of what he did.

Most Commonwealth law in this area is still based on these criteria, and most US law was too, until shortly after John Hinckley shot US President Ronald Reagan and was found not guilt by reason of insanity.

This caused a backlash against the insanity defence and many US states have variously abolished it or made it much more difficult to prove (near impossible in some cases).

The Reason Magazine article examines why, when it does arise, the evidence is largely based on descriptions of the person’s mental state and why recent advances in understanding mental illness don’t really help very much.

One of the main reasons is that studies that find differences between people with mental illness and those without, do so on the group level. The same differences might not be present when comparing any two individuals.

In other words, on average, there are mind and brain differences between people affected by mental disorders and unaffected people, but the individual variation is so great that you couldn’t reliably say it would be present in one particular person.

As these criminal trials are focused on the actions of one individual much of the objective science goes out the window because it can’t reliably indicate an diagnosis, state of mind or reasoning abilities on the individual level.

This means that the most relevant evidence is usually the testimony of a psychiatrist or psychologist who is giving his or her clinical, descriptive judgement of the person’s state of mind.

The Reason Magazine article examines what sort of dilemmas this causes, and considers how developments in psychology and neuroscience are likely to impact on the legal judgement of insanity.

It’s an excellent guide to some of the key issues and the difficulties of making legal judgements on subjective states of mind.

Link to article ‘You Can’t See Why on an fMRI’.

Personalised drugs

The New York Times has an interesting opinion piece on using genetic tests to determine which psychiatric drugs will be most effective and least problematic.

It is starting to become known that people with certain genes or sets of genes react to drugs differently.

These could be genes related to aspects of brain function, or, just as importantly, liver function, because many psychiatric drugs are broken down by enzymes in the liver.

For example, enzyme CYP2D6 metabolises a whole range of psychiatric drugs including antidepressants and antipsychotics.

Some people have certain versions of the CYP2D6 gene which means they have much less of the enzyme and so break these drugs down at a much slower rate.

This means the same dose of the drug in these people will have a much stronger effect, which can lead to increased side-effects.

There are many more examples of how genes influence the effects of drugs, and doctors would ideally like to be able to test people beforehand to see which drugs might be better.

Like most mass-market industries, the drug industry prefers a ‘one size fits all’ approach, advertising their pill as suitable for anyone with a particular condition.

The idea of genetically testing people for drug suitability is causing them a bit of a headache at the moment, as they’re desperately trying to think of ways to make money out of it.

The New York Times article is quite positive about the effect this will have on the relationship between medicine and industry:

Aside from the potential to transform clinical psychiatric practice, these new developments will surely change the relationship between doctors and the drug industry and between the industry and the public. Direct-to-consumer advertising will become nearly irrelevant because the drugs will no longer be interchangeable, but will be prescribed based on an individual’s biological profile. Likewise, doctors will have little reason to meet with drug company representatives because they won’t be able to give doctors the single most important piece of information: which drug for which patient. For that doctors will need a genetic test, not a salesman.

Of course, it could just lead to people with common genes being prescribed cheap, widely available treatments, while those with rarer genetic profiles having to pay more for expensive, niche medicines.

Almost certainly, it will lead to the drug industry getting into the genetic testing market, probably with equally as many advantages and drawbacks as exist with their current marketing strategies.

Link to NYT on ‘On the Horizon, Personalized Depression Drugs’.

Are we computers, or are computers us?

Philosopher Dr Pete Mandik has published an interesting thought on his blog that questions whether the common ‘computer metaphor’ used to describe the human mind is really a metaphor at all.

Cognitive psychology typically creates models of the mind based on information processing theories.

In other words, the mind and brain are considered to do their work by manipulating and transforming information, either from the senses, or from other parts in the system.

It is therefore common for scientists to talk about the mind and brain in computer metaphors, as if they are information processing machines.

Mandik questions whether this is really a metaphor at all:

There is a sense of the verb “compute” whereby many, if not all, people compute insofar as they calculate or figure stuff out. Insofar as they literally compute, they literally are computers. Further, the use of “compute”, “computing”, and “computer” as applied to non-human machines is derivative of the use as applied to humans.

It strikes me as a bit odd, then, to say that calling people or their minds “computational” is something metaphorical.

Indeed, the term ‘computer’ was originally a name for a person who did mathematical calculations for a company.

Calculating machines were then given the supposedly metaphorical name ‘computers’ as they did equivalent work to the human employees.

Mandik questions whether we should think of any of these examples as genuine metaphors, since they’re describing the same operations.

However, a key issue for cognitive science is whether there are reasonable limits in describing mind, brain and behaviour in mathematical terms.

The fact that we can adequately describe some things mathematically doesn’t solve this problem, because there may be things that are impossible to describe in this way which we simply don’t know about.

Often though, we just assume that we haven’t found the right maths yet, when the reality may be far more complex.

Link to Pete Mandik post with great discussion.

2007-06-22 Spike activity

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

Science reports that forced donations activate brain areas associated with altruism.

The New York Times reports that half of all continuing medical education courses in the United States are now paid for by drug companies and are often little more than marketing exercises.

The Neurophilosopher finds some beautiful antique brain anatomy drawings.

Men react more positively to children with facial appearance resembling themselves, suggesting genetic relatedness, while women’s reactions are more influenced by healthy looks.

Pure Pedantry has some fascinating analysis of some 80,000 year-old ornaments.

More coverage on the long-term neurological effects of concussion in NFL players from The New York Times.

Did Hitler have syphilis? Wild speculation abounds in a recent psychiatry conference presentation.

Research has consistently found that materialism makes you unhappy, but The New York Times reports that it may not make you better off either.

What makes a movement seem artificial? Cognitive Daily looks at how we perceive movements in computer animations.

Self-effacing people are secretly confident, suggest new study on the differences between declared and inner self-esteem.

Backlash over child bipolar disorder: Scathing articles published in the SF Chronicle and Boston Globe.

Mixing Memory published an gripping article on the psychology of metaphors that generated two great follow-ups.

Discover Magazine looks at the new generation of aptitude measurements in psychology that hope to go <a href="http://discovermagazine.com/2007/may/blinded-by-science
“>beyond IQ.