Month: June 2007

Amazon tribe challenges the structure of language

Chomsky famously argued that a core property of all language was recursion – the ability to include units of meaning inside other units. Anthropologist Daniel Everett argues in an article for Edge that the language of the Pirah√£ people is not like this, and might suggest that our understanding of the structure of language needs to be re-thought.

Language researchers like Noam Chomsky and Steven Pinker are often called ‘nativists’, meaning they think our core language abilities are inherited and suggest that all the individual languages have the same underlying components.

Research based on this idea looks at the structure and neuroscience of language to try and work out the basic elements.

Chomsky and colleagues argued in a 2002 paper [pdf] that human language has only one core property – recursion, which Everett also describes in his article:

The essence of human language is, according to Chomsky, the ability of finite brains to produce what he considers to be infinite grammars. By this he means not only that there is no upper limit on what we can say, but that there is no upper limit on the number of sentences our language has, there’s no upper limit on the size of any particular sentence. Chomsky has claimed that the fundamental tool that underlies all of this creativity of human language is recursion: the ability for one phrase to reoccur inside another phrase of the same type. If I say “John’s brother’s house”, I have a noun, “house”, which occurs in a noun phrase, “brother’s house”, and that noun phrase occurs in another noun phrase, “John’s brother’s house”. This makes a lot of sense, and it’s an interesting property of human language.

Finding a language which doesn’t have the supposedly ‘universal’ property of recursion challenges the Chomsky theory and, potentially, the whole idea that a ‘language instinct’ is somehow genetically inherited.

Everett argues that the Pirah√£ language doesn’t have recursion (or numbers and few colour names), presumably partly as a result of the particular habitat that the tribe lives in.

Everett’s article is also fascinating as it describes his first encounter with the Pirah√£ as a Christian missionary, and his subsequent rejection of his missionary work and focus on linguistics.

It also describes the culture and mindset of the people and has some of Everett’s personal reflections on his research and experiences.

There’s also a video about the topic and its possible effect on our understanding of language on the same page, and a recent NPR radio show investigated the Pirah√£ controversy in more detail.

UPDATE: Many thanks to Austin for sending in a link to an enjoyable article from The New Yorker that is a fantastic guide to the language and its impact on science.

UPDATE 2: There are some fantastic comments, corrections and additional links in the comments that are definitely worth reading. Thanks to everyone who’s contributed!

Link to ‘Recursion and Thought: Why the Pirah√£ don’t have numbers’.
Link to NPR radio show.

Smuggling drugs into the brain

Open-access science journal PLoS Biology has a fascinating article on the latest developments in getting drugs across the blood-brain barrier – the body’s strict border control that keeps the brain free of foreign substances.

The blood-brain barrier is a filtering system in the capillaries, the smallest blood vessels in the brain, to prevent molecules over a certain size reaching the brain itself (click image for larger version).

This makes good biological sense as it keeps the brain free of a whole range of potential poisons and infections but is a pain for drug designers.

There are many drugs which would have an effect but can’t get from the blood into the brain because the molecules are too big.

For example, Parkinson’s disease involves the death of dopamine neurons in the nigrostriatal pathway of the brain – a key circuit for movement – which is partly why the disease causes tremor and rigidity.

The obvious thing to do would be to give people dopamine to make up for the lost neurons, but it turns out that dopamine molecules are too big to cross the blood-brain barrier. If you swallow a dopamine pill, it won’t reach the brain.

Eventually someone hit on the idea of giving people levodopa or L-DOPA – a molecule that the body eventually transforms into dopamine and is small enough to cross the barrier.

So, you swallow an L-DOPA pill, it crosses the barrier and is changed into dopamine inside the brain itself. Clever.

Substances given with the intention that the body will transform them into the desired drug are called prodrugs and finding prodrugs small enough to cross the blood-brain barrier is one method for getting round the delivery problem.

This is fine if what you’re trying to deliver can be transformed into something useful but for many drugs this isn’t possible, so other methods have to be found.

New techniques are being developed which take advantage of the fact that the blood-brain barrier makes special exceptions for certain essential proteins.

The idea is that a drug molecule will be ‘wrapped up’ in a familiar protein and so will be smuggled across the barrier, only to be released when it reaches the other side.

Other techniques involve a mechanical approach to the problem where a device is implanted to pump the drug straight into the brain. Needless to say this direct intervention approach is favoured by neurosurgeons (the armed wing of the neuroscience world).

The PLoS Biology article discusses these are other developments and looks at how this problem is now becoming a core focus of drug development as useful medicines have sometimes been invented only to be found to be unusable in practice.

Link to PLoS Biology article ‘Bridging the Blood-Brain Barrier’.

Fatherhood in the mind and brain

Both Time and Slate have just run articles on the often neglected field of fatherhood, where they report on the significant brain changes and unique psychological processes linked to male parenthood.

I sometimes think you can’t blame fathers for feeling like they’re unimportant when science has relegated them to a footnote in the parenting process.

This is slowly beginning to change and increasingly research is showing that fatherhood and impending-fatherhood has a unique effect on the mind and brain.

For example, fathers have unique hormonal changes during their partner’s pregnancy and when interacting with their child that significantly affects their brain.

And yet despite these findings, few scientists treat the physiology of fathers as a serious subject in its own right. Researchers have been investigating some of the hormonal swings in humans for almost a decade, and longer in other species; still, most of this work remains on the fringe. Between 2000 and 2006, the journal Hormones and Behavior published nearly three times as many studies of mothers as of fathers, and this year the count so far is 16 to three. A 2000 review framed research into physiological fatherhood as “an opportunity to better understand maternal behavior, by studying parental behavior in the absence of pregnancy and lactation.” Interest in how men’s bodies prepare themselves for fatherhood only seems to matter to the extent it sheds light on mothers. Meanwhile, the ways in which dads screw up their kids is a thriving area of research.

It’s also interesting how stories on fatherhood are presented.

BBC News recently reported on a new study (which I haven’t been able to track down yet, except as a press release) that looked at couvade syndrome – where fathers experience physical symptoms as their partners go through pregnancy.

This is entirely explained in terms of ‘anxiety’ and being ‘attuned’ to their partners.

This is despite the fact that researchers have been arguing for over a decade that the syndrome is equally as influenced by the biological changes brought on by fatherhood.

In contrast, the popular reporting on pregnancy and women is awash with the effects of hormones on behaviour and often ignores the psychological aspect.

In other words, women who experience changes in thinking or behaviour are described if they’re slaves to their hormones whereas symptoms in men are due to anxiety and over-identification.

It’s an interesting twist on how our stereotypes about sex roles and parenting play out in science and popular culture.

The Time and Slate articles attempt to redress the balance by examining research on the role of fathers and how their body and brains react to pregnancy and childcare.

Link to Slate article on what fatherhood does to the body and the brain.
Link to Time on the psychology of fatherhood.

A Trephined Irish Skull

Many thanks to Alex and the Neurophilosopher, who sent in the article I had no luck getting hold of in the previous post on trepanation – the surgical technique of putting a hole in the skull.

The brief article is from the 1923 edition of the anthropology journal Man and describes ninth century brain surgery on a 22-year-old man.

If you’re wondering why it describes the operation as trephination, it’s an alternative word for trepanation. Click on the image for a larger version.

A Trephined Irish Skull
Man, Vol 23, (Nov 1923), p180
Thomas Walmsley

Cennfaelad, a young Irish chief, had his skull fractured by a sword-cut at the Battle of Moyrath AD 637. He was under treatment for a year afterwards at the celebrated school of Tomregan (now in Co. Cavan), where the injured part of his skull and a portion of his brain were removed. He recovered and afterwards became a great scholar and a great jurist. Such is one record of early Irish surgery.

The skull reproduced here (Fig. 1) is that of a young male about twenty-two years of age, which was obtained, along with a number of other skulls, from early Christian (ninth century) graves at Nendrum Monastery in Island Mahee, Strangford Lough. The other skulls, with a few more of the same period from another locality, I hope to describe at a later date, but this one is of sufficient interest to be described separately.

For on the left side, towards the anterior-inferior angle of the parietal bone and just within the temporal line, there is a trephined opening. The diameter of the opening is 8mm, but it originally must have been more, for the edges have healed all round; this can be seen better on the inner surface. Round the opening, on the outside of the skull, for a distance of 3mm, the bone is bevelled as if it had been scraped away. On the inside there is no such bevelling; rather the bone is slightly raised and tuberculated round the original margin of the opening.

There are no marks of injury on the skull, and there is no evidence of disease. The deficiency above the mastoid is due to the falling out of a sutural element.

2007-06-15 Spike activity

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

The New York Times has an article on the controversial diagnosis of sensory integration disorder.

Simon Baron-Cohen writes on The Biology of the Imagination in Entelechy magazine.

Neanderthals were less likely to be mentally ill according to some speculative research.

The Society for Neuroscience has a useful list of online neuroscience databases.

Alzheimer’s disease may quadruple by 2050 according to projections in a recent study.

A psychologist claims he spotted a live dinosaur in 1971. You read it here first.

Hugs are more effective for comforting women, words better for men, according to a new study reported in The Independent.

MeFi features the art of Alexander Pavlovich Lobanov, Russian deaf-mute confined to psychiatric institutions for over 50 years.

A funny letter in this week’s New Scientist warns about the tragedy of Juvenile Obnoxiousness Disorder.

Developing Intelligence investigates the autobiographical blur between fantasy and reality.

Women are more likely to be attracted to men who share physical similarities with their father but only if they had a good relationship with him, reports Live Science.

PsyBlog covers a curious study on how the speed and flow of men’s urination in a public lavatory was affected by invasions of personal space.

BBC News has an article on Couvade syndrome, where men experience physical symptoms associated with pregnancy.

The Phineas Gage Fan Club finds a wonderful demonstration of diffusion tensor imaging – a brain scanning technology that maps white matter connections in the brain.

The reflected relationship: the science of transference

This week’s Science News has an article on transference, originally a Freudian concept of how feelings from one relationship can affect another if the two people share similarities.

In its simplest sense, transference is taking out your feelings of frustration on your partner when you’ve just had an argument with the bus driver. You’ve just transferred them from one person to another.

More commonly, it’s used to describe the idea that you re-experience certain feelings and relationship patterns you developed with important people in your childhood when you meet new people who share similarities with the original person.

In other words, if you didn’t trust your father, you’re less likely to trust people who remind you of your father.

Transference is key in Freudian psychotherapy, where the therapist attempts to be a ‘blank screen’ onto which the patient can project and transfer their feelings through the therapeutic relationship.

This allows the therapist to see the process in action and make the patient aware of it, so they can change and improve their relationship patterns.

This is one Freudian concept that has remained quite popular in modern psychology, although it’s rarely been subjected to controlled research.

This is beginning to change, however, as some researchers are starting to test the idea experimentally, and finding that the effects seem to be measurable in the lab.

The Science News article looks at some of the research being conducted by Profs Susan Andersen and Glen Gabbard that has been exploring this interesting interpersonal effect.

Link to Science News article ‘Past Impressions’.

The latest in sleep science

A Blog Around the Clock has a couple of useful posts that collect the highlights from one of the biggest international sleep research conferences.

Sleep 2007 finishes today in Minneapolis and is a mecca for psychologists and biologists wanting to understand this still mysterious process.

If you want to have a look at exactly what’s been discussed, the programme is available online, although A Blog Around the Clock links to more comprehensive articles about some of the most interesting developments.

Link to A Blog Around the Clock conference coverage part 1.
Link to A Blog Around the Clock conference coverage part 2.

Like a hole in the head: An illustrated history of trepanation

Neurophilosopher has written an absolutely fantastic post on the history of trepanation – the surgical procedure that has been carried out since prehistoric times and involves drilling a hole in the head.

Neurophilosopher always has great articles but this is also wonderfully illustrated and has all the gory details of this fascinating procedure.

The trepanned skulls found at prehistoric European sites contained round holes, which varied in size from just a few centimetres in diameter to nearly half of the skull. They are most commonly found in the parietal bone, and also in the occipital and frontal bones, but rarely in the temporal bone. In the earliest European skulls, the holes were made by scraping the bone away with sharp stones such as flint or obsidian; later, primitive drilling tools were used to drill small holes arranged in circles, after which the piece of bone inside the circle was removed. The late Medieval period saw the introduction of mechanical drilling and sawing instruments, whose sophistication would continue to increase for several hundred years.

The article takes you through the prehistoric origns of the procedure, to how it developed around the world, to its modern uses for surgery and recreation (yes, recreation!).

The picture at the top is from a trepanned skull from the Hunterian museum in London that also showed signs of neurosyphilis infection. There’s more about it in a previous post.

I also found a good example of a trepanned skull in the National Museum of Ireland but unfortunately they don’t allow pictures and don’t have images of it available.

However, this article has an interesting snippet about the various examples of the procedure discovered in the country:

From Ireland several interesting examples are available. A trepanned skull of a thirteen-year-old child, probably early Christian, was recovered from Collierstown in Co. Meath (Martin, 1935). Two further trepanations each of late Mediaeval date, one from Ballinlough (Co. Laois) and the other from Maganey Lower (Co. Kildare), were found during recent excavations.

A fourth specimen was discovered in a stone-lined grave at the Abbey of Nendrum on Mahee Island in Strangford Lough (Martin). The abbey was destroyed in 974 A.D. by fire. It is highly likely that in those days “major surgery” was performed in monastic institutions (Fleetwood, 1951). Legend has it that Cennfaeladh, whose skull was fractured by a blow from a sword during the battle of Moyrath in Co. Down (637 A.D. ), was operated upon by St. Bricin, the Abbot of Tuaim Drecain, an accomplished surgeon and scholar (Fleetwood).

And this page has an image of a 7th century gargoyle-esque carving of St Bricin with trepanning tools in one hand and a skull in the other.

Apparently, the treatment worked so well that Cennfaelad, an Irish chieftan, recovered his intellect and improved his memory so that on his recovery he became a great scholar, whose name ‘Kennfaela the Learned’ is known in Irish literature to this day.

There’s more about this case, and about trepanning in Ireland, on this page, and, if you’ve got a subscription to JSTOR, which I don’t have unfortunately, there’s an academic article here. Do let me know if you can get hold of a copy!

Link to Neurophilospher on ‘An Illustrated History of Trepanation’.

Cognitive science news mashup

CogNews.net is a website that takes feeds from a number of cognitive science sites and puts them in one place for your viewing pleasure.

It has three categories with feeds from a few essential sites in each: Mind and Cognition (which includes us!), Neuroscience, and Artificial Intelligence and Robots.

The site has been put together by Marek Kasperski who obviously gets as much of a kick from cognitive science as we do.

Link to CogNews.net.

New brain scan combines best of both

ScienceDaily reports that the first images from a new type of brain scanner that combines both magnetic and radiation-based imaging have been shown at a recent medical conference.

The new technology is called MR/PET because it allows magnetic resonance and positron emission tomography scans to be conducted at the same time.

MRI uses very strong magnets that align the spin of the atoms in your body. It then sends a radio pulse which knocks the atoms out of alignment.

After the knock, the atoms return to their previous alignment but the time taken will differ, depending on the body tissue. As they return, they send off their own pulse, and this can be picked up and turned into an MR image of the tissue by computer software.

PET involves adding a small amount of oxygen or glucose into the body that the brain uses to do its work. Crucially, the substance has been altered so it is slightly radioactive.

As the brain works, the areas that are most active will be slightly more radioactive, and this can be measured to generate a map of brain activity.

You can create similar maps using functional MRI, but one advantage of PET is that it is especially good at ‘resting PET’, meaning you’re not asked to do any tasks. It just gives a general picture of which brain areas are most active.

This is particularly useful if the medical team think your brain might be structurally intact but may have areas which are under or overactive, or want to know the effects of structural damage in one area on function in the rest of the brain.

PET can also be used to track the effects of specific chemicals in the brain (by making them slightly radioactive and injecting them), which is something that fMRI currently can’t do very well.

Previously, to combine the two scans, someone would have to go into a MR scanner to get a structural image, and then go into a PET scanner to get a measure of activity, and computer software would impose the PET image onto the MR image.

This causes problems because the two images aren’t perfectly aligned and so information gets lost.

Imagine you are trying to fit a photo you took from an airplane onto a street map. You might need to stretch or edit the photo to make it fit properly, and in doing so, you might miss bits out or blur important details.

The reason the combined MR/PET will be useful is that the two scans are taken at exactly the same time, so no information is lost.

It also means patients with fragile brains won’t need to be moved between scanners.

One of the difficulties with combining the types of scanning before is that PET normally uses photomultiplier tubes to detect the effects of radiation, which don’t work in magnetic fields, but now new sensors have been developed which are MR safe.

Unfortunately, I can’t seem to find any images of the new scans online (please let me know if you find or have any!).

However, if you want to know more, Radiology Today magazine has a more in-depth article and Siemens, the creator of the technology, has some information as a webpage and pdf.

Also there’s an image of the scanner from a Cambridge University team also working on the technology.

Link to ScienceDaily on new MR/PET images.
Link to Radiology Today article on the technology.

Bullets, bleeds and bangs – brain injury animations

Brain injury resource site Neuroskills has a nifty page of brain animations, including a selection showing how various types of brain injury occur.

They’re a bit clunky in places and the point of injury seems to be illustrated with a small science-fiction-like stellar explosion, but they’re genuinely informative and quite fun to watch at times.

They include the effect of a bullet to the head, stroke, shaking injuries, animations highlighting the main anatomical areas, the functioning of healthy and damaged neurons and a few others thrown in for good measure.

Link to Neuroskills animations gallery.

The psychology of self-accusation, from 1902

Every month, the British Journal of Psychiatry has a section that prints 100-year-old excerpts from medical journals relevant to modern psychiatry.

They are usually both fascinating and shocking. As a brief window on the past, they can show a very different understanding of mental disorder, but not always the respect that people with psychiatric difficulties deserve.

This from a 1902 letter to the Lancet about people who go to court to accuse themselves of a crime that they haven’t committed.

The committal of a notorious crime which excites popular imagination and which remains undetected for a time often leads to the appearance in law courts of self-accusing culprits who charge themselves with being the authors of the crime in question. Dr. Ernest Dupr√© of Paris in a paper read before the Annual Congress of French Alienists and Neurologists recently held at Grenoble attempts to delineate with exactitude the psychological nature of “auto-accusation” and to show that certain morbid elements play an important part in it.

He points out that “auto-accusation” is not often or merely the result of a weak-mindedness; the subject of it is a person who has positively developed general ideas of unworthiness, guilt, and remorse, and in a word is suffering from mild melancholia with vague delusions of guilt and sin. Another type of self-accuser is the proud and vain “degenerate” who with a brain warped by congenital anomaly of development constructs romances of which he readily persuades himself to be the hero or the martyr.

There is, adds Dr. Dupré, a marked contrast between these two types. The one is abject, lowly, self-humiliating; the other proud, egiostic, and vain. Among other types of the same abnormality are found persons of alcoholic or hysterical character.

The full letter goes on to describe the supposed characteristics of the ‘alcoholic self-accuser’ and the ‘female self-accuser’ who was apparently likely to be suffering from ‘marked hysteria’.

One of my favourites is a curious case report of a Cambridge student who had seemed to have lost his identity.

There’s many more historical gems in the archives that are well worth checking out.

Link to ‘100 years ago’ section of the British Journal of Psychiatry.

Detect lies by getting the story in reverse order

The Times has an interesting piece on a police interview technique that asks the suspect to tell the story in reverse order. A recent study has found this makes it more likely that liars will give themselves away.

The research has been conducted by Prof Aldert Vrij and colleagues who specialise in the psychology of police interviews and deception.

The idea behind it is that you have to expend considerable effort when you’re lying not to look stressed and to make sure your story doesn’t contradict itself.

One way of making this less easy, is to put additional strain on your mental resources by asking you to do something more difficult with the story.

This is especially tricky for liars, because for people who are telling the truth, explaining the events in reverse order is less of an effort than for people who are making the story up.

When someone is using their concentration to do this harder task, they will concentrate less on making sure they look comfortable with their story, and so are more likely to let signs of stress slip out.

On the other hand, they may have to concentrate harder on making themselves look relaxed, and make some errors in their story.

This is known as a type of ‘cognitive load‘ interview and is routinely used in police investigations.

It’s not a sure fire way of detecting deception, because liars who are better at concentrating will be less likely to give themselves away, but it seems to increase the chances of the police working out if the suspect is trying to pull the wool over their eyes.

Deception Blog has some more information about the technique, and some links to additional coverage if you want to explore further.

Link to Times article on the technique.
Link to round-up from Deception Blog.