Month: January 2010

Touch Of Fire

The pictures are the interesting results of an MRI scan on a 15-year-old boy who had his hair in ‘twists’ that were held in place with beeswax coloured black with iron oxide.

The iron oxide is magnetic and it interfered with the scanners’ magnetic field causing the rather lovely aura effect on the images.

This is not the only case of a hair style interfering with a brain scan in the medical literature. An earlier report is remarkably similar, as the iron oxide coloured braids of a 51-year-old lady caused similar flame-like patterns on the scans.

Link to MRI ‘aura’ in 15-year-old boy.
Link to MRI ‘aura’ in 51-year-old lady.

Nuthin’ but a G thang

Dr Petra has an excellent write-up of the new study which has been widely reported as showing there is ‘no genetic evidence for the g spot’, but in fact indicates that there is ‘no genetic evidence for thinking you have a g spot’, which is quite a different thing and doesn’t bear particularly well on whether this famed point of sexual ecstasy really exists.

The research is a twin study, which looks at the differences in how human traits vary between identical twins, who are genetically identical, and regular twins who share, on average, only 50% of their genetic information. The differences between how the trait varies between the two types of twins indicates how closely controlled the trait is by genetics in that sample.

The rationale behind the research is that if the g spot is a genuine fixed anatomical feature, then it should be more likely to be influenced by genetics, as other such features are.

However, this study didn’t measure anything anatomical, it just asked the women whether they thought they had a g spot or not with a single question: ‚ÄúDo you believe you have a so called G spot, a small areas the size of a 20p coin on the front wall of your vagina that is sensitive to deep pressure?‚Äù.

This is a bit of an odd strategy because we’re not necessarily the best guides to our own internal anatomy.

This was demonstrated in 1998 when a study by surgeon Helen O’Connell and colleagues dissected several dead bodies and found that the clitoris was much larger than had been thought for thousands of years and in fact had nerves and blood vessels that extend deep within the body.

Crucially, the sexual experiences of women throughout history had not provided a reliable guide to the anatomy of the clitoris and it took a detailed look at the body’s structures to work this out. This suggests that asking people whether they think they have a particular feature may not be a reliable guide to whether they do.

Dr Petra’s write-up gives an excellent account of the history of ‘g spot’ concept and discusses how this study fits into the bigger picture.

Link to ‘Where have all the g spots gone?’

World-wide cocaine cut mystery

A veterinary deworming drug called levamisole has mysteriously appeared in almost two-thirds of cocaine seized in the United States and is now common throughout the world.

No-one is quite sure why, although some researchers have suggested that it may be added to boost the effect of cocaine in the brain.

Now a brief article in the Journal of Analytical Toxicology suggests this may indeed be the case based on the neurological effects of the two substances.

Street drugs are typically ‘cut’ with additional substances, often to bulk them out, but occasionally to alter the effect of the main substance. As we discussed in a post on adulterants in heroin, this can be a way of changing the drug to give it a different effect to benefit the dealer.

As an excellent article on Erowid notes, the fact that cocaine is cut with only small amounts of levamisole (only 6% of the deal in one study) suggests that it is not being used just as a handy powder to thin out the coke – more likely, it is being added for a specific effect.

Levamisole is, in some respects, similar to nicotine and the drug binds to specific nicotine-triggered receptors for the neurotransmitter acetylcholine and causes the nerve cell to respond. It turns out that this is most likely to increase activity in the body’s ‘fight-or-flight’ system – the sympathetic nervous system.

In fact, this is exactly how the drug has its deworming effect. In worms, it targets nerve cells involved in muscle activity, causing the muscles to contract. The worm is paralysed and so can be easily expelled from the body.

As cocaine also stimulates the body, the two drugs could combine to cause additional arousal.

This effect would largely be on the peripheral nervous system, outside the brain, but levamisole might also boost the effect of cocaine directly within the brain – enhancing pleasurable feelings.

In the brain, levamisole likely also enhances the release of glutamate, a neurotransmitter that is known to encourage or excite the function of neurons.

We known cocaine boosts dopamine function in the reward system, but the reward system is not single brain area. It’s actually a network of related structures deep within the brain that have connections that communicate and feedback their activity levels to carefully tune their running. An essential part of the feedback mechanism uses glutamate.

To use a sound system analogy, if cocaine cranks up the volume by boosting dopamine, levamisole might work by increasing power to the speakers by upping glutamate levels. The effects add up and the high is amplified.

What this means is that dealers can sell less actual cocaine but users get a similar effect from the smaller amount.

However, this comes at a price. The additional ramping up of the ‘fight-or-flight’ system is likely to put an additional strain on the heart and heart failure is one of the most common cocaine-associated fatalities.

Levamisole also causes the immune system to stop working so well by killing off white blood cells (in fact, this is why it is rarely used in humans in modern medicine) and several cases of life-threatening illness caused by levamisole-cut cocaine have already been reported.

The fact that this additive has been appearing at all, is, in itself, quite surprising. The fact that this relatively obscure compound has become so common in the global cocaine industry might suggest that it was selected on the basis of its pharmacological properties.

In other words, on the basis of the study of neuroscience. One study reported that professional heroin cutters can charge up to $20,000 a kilo and I wouldn’t be surprised whether the big players in the cocaine industry can afford to pay for neuroscientists or pharmacologists to tweak their products.

Link to PubMed entry for brief article on possible effects of levamisole.
Link to excellent Erowid reviewing findings on levamisole-cut cocaine.
Link to Wall Street Journal on prevalence of levamisole in US cocaine.

The death row inmate

A summary of an eye-opening 2002 article on the psychological characteristics of prisoners on ‘death row‘ in the United States, published in the journal Behavioral Sciences and the Law.

Death row inmate characteristics, adjustment, and confinement: a critical review of the literature

Behav Sci Law. 2002;20(1-2):191-210.

Cunningham MD, Vigen MP.

This article reviews and summarizes research on death row inmates. The contributions and weaknesses of death row demographic data, clinical studies, and research based on institutional records are critiqued. Our analysis shows that death row inmates are overwhelmingly male and disproportionately Southern. Racial representation remains controversial.

Frequently death row inmates are intellectually limited and academically deficient. Histories of significant neurological insult are common, as are developmental histories of trauma, family disruption, and substance abuse. Rates of psychological disorder among death row inmates are high, with conditions of confinement appearing to precipitate or aggravate these disorders. Contrary to expectation, the extant research indicates that the majority of death row inmates do not exhibit violence in prison even in more open institutional settings.

These findings have implications for forensic mental health sentencing evaluations, competent attorney representation, provision of mental health services, racial disparity in death sentences, death row security and confinement policies, and moral culpability considerations. Future research directions on death row populations are suggested.

It’s a fascinating, if not slightly morbid article, and the full text is available online as a pdf if you want a full breakdown of the research.

Link to PubMed entry for study.
pdf of full text of the article.

The psychology of ‘super-human strength’

Scientific American has an interesting short piece on whether people can really demonstrate super-human strength in emergency situations. The typical story is where someone is trapped under a car after an accident and a friend or relative manages to lift a seemingly impossible weight to free them.

This common tale has all the hallmarks of an urban myth, but it turns out to be partially plausible. Fear seems to increase our available muscle strength – but not by super-human amounts – only by a fraction of our normal lifting power.

Vladimir Zatsiorsky, a professor of kinesiology at Penn State who has extensively studied the biomechanics of weightlifting, draws the distinction between the force that our muscles are able to theoretically apply, which he calls “absolute strength,” and the maximum force that they can generate through the conscious exertion of will, which he calls “maximal strength.” An ordinary person, he has found, can only summon about 65 percent of their absolute power in a training session, while a trained weightlifter can exceed 80 percent…

But there’s a limit to how fast and how strong fear can make us. We’ve all heard stories about panicked mothers lifting cars off their trapped babies. They’ve been circulating for so long that many of us assume that they must be true. Zatsiorsky’s work, however, suggests that while fear can indeed motivate us to approach more closely to our absolute power level than even the fiercest competition, there’s no way to exceed it. A woman who can lift 100 pounds at the gym might, according to Zatsiorsky, be able to lift 135 pounds in a frenzy of maternal fear. But she’s not going to suddenly be able to lift a 3,000-pound car.

The SciAm article is apparently an excerpt from a new book entitled Extreme Fear: The Science of Your Mind in Danger.

Link to SciAm excerpt on ‘super-human strength’
Link to book website.

2010-01-01 Spike activity

Quick links from the past two weeks in mind and brain news:

The Wall Street Journal has an excellent article on the psychology of will power in light of the season for New Year’s resolutions.

As a follow-up to the review of the year, Dr Petra discusses some sex and relationships predictions for 2010. By the way, Dr Petra just arrived on Twitter. You can follow her @DrPetra

The New York Times discusses ‘pleasure procrastination’ where people put off pleasurable activities often to the point of never doing them. See also the psychological concept of ‘hyperopia‘.

An innovative study finding it’s possible to treat tinnitus with specially designed music is covered by Not Exactly Rocket Science.

The LA Times has a brief obituary for Ruth Lilly, heiress to the Eli Lilly fortune and philanthropist, who spent much of her life in psychiatric hospital struggling with depression.

The 12 psychology studies of Christmas are featured on PsyBlog.

Science Daily covers a study finding that lighting can influence how we perceive the taste of wine.

There’s an excellent piece on the health effects of television viewing over at Seed Magazine.

The Neurocritic covers one of the brilliant light-hearted studies in the Christmas edition of the British Medical Journal. This one on the relationship between the Dow Jones Industrial Average and the value of coins swallowed by children.

The brief history of how psychoanalysis shaped consumer culture via Freud’s nephew Edward Bernays is discussed in the APA Monitor magazine.

The Neuroskeptic covers the launch of the free online neuropathology database – the Stanley Neuropathology Consortium brain collection.

Elyn Saks is a law professor at the University of Southern California, a Marshall scholar, and a graduate of Yale Law School, and has a diagnosis of schizophrenia. Scientific American has an interview.

Frontier Psychiatrist has a brief piece on Couvade Syndrome where men show ‘sympathetic’ signs pregnancy-like when their partners are pregnant.

There’s an interview with fear specialising psychologist Daniela Schiller in the latest Discover Magazine.

The BPS Research Digest covers a studying on how doodling can boost memory and concentration.

Why do more women than men still believe in God? asks Double X magazine.

Scientific American has an article on optogenetics or the use of light and genes to probe the brain.

Seeing the humanity in brain-damaged youths. The Boston Globe has a piece on looking beyond the sometimes erratic behaviour of young people with neurological problems.

Psychiatric Times has a good write-up on atypical antipsychotics increasing cardiometabolic risks in children.

The development of the brain in old age and ‘how to train the aging brain‘ is tackled by The New York Times.

If you’re a Twitter user and interested in criminology and crime, I recommend following @crime_economist.

Discover Magazine has a brief piece on how child abuse leaves its mark on the victim’s DNA.

There’s an articulate, almost poetic account, of living with ALS motor neuron disease in the New York Review of Books.