Category: Inside the Brain

Natalie Portman is best known for her roles in Hollywood movies like Star Wars, Cold Mountain and V for Vendetta. What is less known is that she was co-author of a scientific paper on the neuroscience of child development. This is about her research.

Portman, whose real name is Natalie Hershlag, left acting to pursue a psychology degree at Harvard during 2000.

While there she was employed as a research assistant in Prof Stephen Kosslyn’s neuropsychology lab where she got involved in a study investigating the link between frontal lobe development and visual knowledge in infants.

The study investigated object permanence – the ability to understand that objects do not disappear from the world when they are out of sight, something that typically develops in the first year of life.

Researchers have argued that the frontal lobes are particularly important for this skill, but the trouble is, you can’t put babies in conventional brain scanners to easily test the idea. They just wriggle about too much.

Portman’s study, led by neuroscientist Dr Abigail Baird, used a relatively new method for measuring brain function called near-infrared spectroscopy.

This technology relies on the fact that near-infrared light can penetrate the skull, and that blood carrying oxygen, and blood that has given up its oxygen, absorbs the light differently.

The idea is that the device beams light into the frontal lobes, and you can work out how hard this area is working from how much oxygen-rich blood there is.

The advantage is that this technology is safe for children, and can be worn as a sort of high-tech hat, meaning there’s less of a problem if the child being tested moves about.

During the study, infants were shown a toy, which was then hidden under a cloth. Children who have object permanence – who know that it hasn’t disappeared – look for it under the cloth.

Children without this skill just ignore the cloth and look for something else to do, because the memory of the toy is gone.

The study tested 20 infants, every four weeks, from the ages of 5-12 months. To see what changed in the brain as the ability emerged, the researchers compared infrared light absorption from a time when the kids first looked for the toy, to an earlier time, when they just forgot that it existed when it was out of sight.

The team discovered that the frontal lobes suddenly kicked in when children develop the knowledge that hidden objects still exist, providing an understanding of which brain areas are involved in this important mental function.

The study also demonstrated that near-infrared spectroscopy could be used successfully to study the brain development of very young children.

The paper was eventually published in the journal Neuroimage, under Natalie’s real name, with the title ‘Frontal lobe activation during object permanence: data from near-infrared spectroscopy’.

It has since been cited by at least 20 different studies that have built on its findings.

And if you want to read the study in full, it is available as a pdf file at the link below.

pdf of Neuroimage paper.

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’.

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.

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’.

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.

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.

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.

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).

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).

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’.

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.

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.

Simultanagnosia is where a person can’t perceive more than one object at a time. They literally cannot see the wood for the trees. There are two main types that differ depending on the location of the brain injury which has caused the syndrome.

Damage to the dorsal stream can cause dorsal simultanagnosia, where the patient cannot see two or more objects at the same time.

Damage to the ventral stream can cause ventral simultanagnosia, where the patient can see multiple objects, but can only identify one at a time.

The following is from p61 of the 1970 book Brain Damage and the Mind (ISBN 0140801405) by Moyra Williams, who describes a gentleman with dorsal simultanagnosia:

A sixty-eight-year old patient studied by the author had difficulty finding his way around because “he couldn’t see properly”. It was found that if two objects (e.g. pencils) were held up in front of him at the same time, he could see only one of them, whether they were held side by side, one above the other, or one behind the other.

Further testing showed that single stimuli representing objects or faces could be could be identified correctly and even recognized when shown again, whether simple or complex… If the stimuli included more than one object, only one would be identified at one time, though the other would sometimes “come into focus” as the first one went out…

If long sentences were presented, only the rightmost word could be read… If a single word covered as large a visual area as a sentence which could not be read, the single word was read in its entirety… If the patient was shown a page of drawings, the contents of which overlapped (i.e. objects were drawn on top of one another), he tended to pick out one and deny that he could see any others.

Recent evidence has suggested that although the unseen objects may not be consciously available, carefully designed psychological tests can detect they have been registered at some unconscious level.

The book Visual Agnosia by Prof Martha Farah covers a number of curious object perception disorders that occur after brain injury, including simultanagnosia.

The book’s webpage has a table of contents and some sample chapters freely available online.

Link to webpage for Visual Agnosia.

In a study investigating how the brain generates paranormal experiences and psychotic states, researchers used strong electromagnets to alter brain function and found they could reduce the number of times healthy volunteers saw spontaneously experienced false perceptions.

The researchers altered the function of the temporal lobes with a method called transcranial magnetic stimulation or TMS while participants were asked to detect supposedly ‘hidden’ images in what were actually completely random dot patterns.

When compared to a control area at the top of the head, reducing left temporal lobe function significantly reduced the number of false perceptions.

During the procedure, participants were asked to look at a series of quickly presented dot patterns and told to indicate which had images ‘hidden’ within them.

Crucially, they were told not to guess and only to press a button when they genuinely detected a ‘hidden’ image. In actual fact, all the dot patterns were completely random and none contained ‘hidden’ images, so every ‘detect’ response was a false perception of meaningful information.

Just before each dot pattern was presented, the brain was stimulated with a pulse of TMS, either to the left or right temporal lobe, or a control spot at the top of the head known as the vertex.

TMS uses magnetic pulses to safely ‘switch off’ a small area of brain for a several hundred milliseconds.

When compared to the control area, temporarily ‘switching off’ an area on the left temporal lobe significantly reduced the number of false perceptions, suggesting that this brain area is likely to be involved in making meaningful connections, even when there’s no meaning to be found.

Seeing meaningful information in random data is known as ‘apophenia’ and statistically is known as a false positive or a Type I error.

Previous research has shown that this tendency is known to be enhanced in people who report high levels of paranormal experience, and to a greater extent, in people who experience psychosis – the mental state involving delusions and / or hallucinations that is most commonly linked to schizophrenia.

Other evidence suggests that differences in temporal lobe function are common in people diagnosed with schizophrenia.

The paper is published in the May edition of Cortex, but a pre-print is available at the link below if you don’t have access to the journal.

pdf of full-text paper.

Disclaimer: This study is from my own research group

Neurophilosopher has a great article on a brain scanning study showing that people with synaesthesia have different patterns of brain connections compared to non-synaesthetes.

You read a lot of articles on the brain that use phrases like “wired differently”, suggesting that the connections in the brain are altered.

As the connections in our brain are changing all the time at the dendrite level, often this is just a meaningless way of saying “there’s a difference”.

Perhaps these sort of phrases are best applied to white matter which is the nearest you’ll find to genuine wires in the brain.

White matter fibres run in bundles, they carry electrical signals, and they are insulated by a fatty covering called myelin.

The connections of white matter have been quite hard to study in living people until the development of diffusion tensor imaging (DTI), a brain scanning technology that can specifically pick out the white matter fibres and create maps like the one in the picture.

Rarely when articles talk about “different brain wiring” do they actually mean detectable differences in white matter though.

In the DTI study covered by Neurophilosopher this is exactly what was studied, and it does indeed seem to be different in people who experience synaesthesia, a condition where some of the senses are crossed so, for example, numbers might be also experienced as colours.

DTI is a type of magnetic resonance imaging (fMRI) that measures the diffusion of water molecules. In the brain, water diffuses randomly, but tends to diffuse easier along the axons that are wrapped in myelin, the fatty protein that insulates nerve fibres. Diffusion tensor imaging can therefore be used to infer the size and direction of the bundles (or “fascicles”) of white matter tracts that connect different regions of the brain (above).

The Dutch researchers show that synaesthetes have more connections between the two adjacent areas in the fusiform gyrus than non-synaesthetes. They report their findings in the June issue of Nature Neuroscience.

As well as showing these differences between synaesthetes and non-synaesthetes, the authors also show that there are also differences in connectivity between synaesthetes who differ in the intensity of their sense-mixing experiences.

In other words, the researchers found people with synaesthesia had white matter ‘wiring’ between sensory areas that others don’t have, and that this wiring differed depending on how much synaesthesia the participants experience.

Just from the fantastically straight-forward explanation of DTI imaging given above, you can see that it’s a wonderfully written article.

Have a look at the full piece for more on this fascinating study.

Link to Neurophilospher on ‘Imaging of connectivity in the synaesthetic brain’.
Link to abstract of scientific study.

The ANZ Journal of Surgery just published the summary of a conference paper describing 12 patients with head injuries caused by nail guns. It makes for some surprising reading.

You might think brain injuries from nail guns would be rare, but there are a startling number of case studies in the medical literature.

A recent review of suicide attempts by nail gun noted it was unusual, but this new case series suggests that many of this type of brain injury are caused in this way.

In fact, out of the 12 cases, three quarters were attempting to kill themselves.

Mostly, the cases concern a single nail, but one case was particularly extreme:

The other case involved a staggering 24 nails of 5cm length and represents the largest number of intra-cranial nails in a surviving patient.

This beats the previous record of 12 nails, held by a man reported in a case study from a neurosurgery team in Portland, Oregon.

The picture is the X-ray of Isidro Mejia, who survived a nail gun accident in 2004, where he was unfortunate enough to have four nails embedded in his skull and two in his neck.

Removal of a nail often involves a craniotomy, where the surgeons have to cut around the bit of skull where the nail is embedded, and remove it in one piece.

There are some images of this operation in an article from the Spanish language neurosurgery journal Neurocirugía which is available online as a pdf.

Link to abstract of nail gun head injury case series.
pdf of Spanish language case report of neurosurgical nail removal.