Month: July 2005

The Guardian reports on psychologist Judith Reisman, who argues that pornography is an ‘erototoxin’ that damages the brain, impairing cognition and rational thought:

“According to Dr Judith Reisman, pornography affects the physical structure of your brain turning you into a porno-zombie. Porn, she says, is an “erototoxin”, producing an addictive “drug cocktail” of testosterone, oxytocin, dopamine and serotonin with a measurable organic effect on the brain.”

In the first instance, she’s right. Pornography does physically affect the brain. In fact, everything we experience physically changes the brain in some way.

What Reisman is trying to do, is portray this physical effect as ‘damage’. Furthermore, she argues the damage could be so severe, that an affected person would not be rational enough to engage in ‘free speech’ (notice the leap?).

Unfortunately, her self-published paper The Psychopharmacology of Pictorial Pornography Restructuring Brain, Mind & Memory & Subverting Freedom of Speech (PDF) is highly selective when reviewing the published neuroscience research.

Many of her arguments are based on one-reference claims, and some only on what she calls “extensive documentation”. One unmentioned implication is the fact that, if sexual arousal from pornography causes ‘brain damage’, then so will real-life sex!

Critics note that Reisman is associated with the Lighted Candle Society, a right-wing Christian organisation aiming to promote ‘moral values’ and fund anti-porn brain scanning studies.

Ironically, her paper is prefaced by a note saying it is restricted to adults over 18, as it contains ‘graphic images from mainstream pornography’.

Link to Guardian piece ‘Sex on the brain’.
PDF of ‘The Psychopharmacology of Pictorial Pornography Restructuring Brain, Mind & Memory & Subverting Freedom of Speech’ by Judith Reisman.
Link to critical piece on Reisman’s work.
Link to story from Desert News on the funding of anti-porn MRI studies.

On Sunday night, the BBC ran the first part of their Secrets of the Sexes series which claimed to rank the show’s participants by ‘brain sex‘, on a scale from 100% male brain to 100% female brain.

The trouble is, there is no objective measure of the sex of the brain, making the whole idea of ‘brain sex’ questionable.

During the show, a number of participants complete various tasks, and their performance allows them to be placed along the scale. The BBC even has an online test allowing you to rate yourself.

The rating of ‘brain sex’ seems to be based on Simon Baron-Cohen’s theory that males and females are likely to differ in skills he calls empathising and systemising.

Empathising is described as the ability to understand and relate to others’ emotions, systemising the tendency to understand things in terms of rules or component parts.

Females tend to score higher on Baron-Cohen’s test of empathising, and males on systemising. So how does this get transformed into the concept of a 100% male or female brain ?

Firstly, it assumes that Baron-Cohen is correct about his theory. This is a big assumption as it is still controversial. Among others, psychologist Elizabeth Spelke has noted several important objections.

Secondly, it involves making an absolute statement (e.g. ‘there is a 100% female brain’) from relative data – e.g. ‘females have a tendency to score higher on the empathising test’.

By using another test, however, alternative differences between males and females can be found. In other words, the rating of how ‘male’ or ‘female’ a person’s brain is, depends on what test is used – something which seems to rubbish the idea of describing any brain as a particular sex.

Instead of describing someone as having a ‘50% female brain’, it is more accurate to say, “compared to everyone else’s performance, on these tasks you scored mid-way through the range of typical female scores”.

Some might say the BBC are just trying to communicate science in a straightforward way, but consider how misleading this sounds: “You have a 50% female foot”. Oversimplified to the point of confusion.

Link to BBC ‘Secrets of the Sexes’ website.

A review article in this week’s British Medical Journal questions whether antidepressants have any more effect than placebo.

The report, authored by psychiatrist Joanna Moncrieff and psychologist Irving Kirsch, analyzes data used in previous healthcare recommendations, concerning a class of antidepressants called SSRIs, of which Prozac is the most famous.

They argue that the improvements found in previous reviews of the data have either been so small that they are clinically insignificant, or have been due to errors or biases in analysis.

In response, Darrel Reiger from the American Psychiatric Association is quoted as saying the researchers have “written an article that selectively pulls out negative studies and conveniently ignores or mischaracterizes positive studies.”

Link to BMJ article ‘Efficacy of antidepressants in adults’.
Link to story from Yahoo News.
Link to story from WebMd.com

Mind Hacks favourite All in the Mind has an special on wisdom, learning and the development of the brain through the lifespan:

None of us are getting any younger. As our bodies show signs of wear, so do our brains. We get forgetful, are confronted by new ideas and perplexed by new technologies. The world appears to be moving way too fast, as we sink into memories of the good ol’ days. Eminent neurologist and author Elkhonon Goldberg argues we have no excuse. His message – make your brain sweat if you want to enjoy your mental life to its fullest. And his suggestion is that the two hemispheres of our brain age differently as we wise up.

mp3 or realaudio of programme.
Link to programme transcript.
Link to ABC Radio National ‘All in the Mind’ website.

A paper in science journal Cell reports on a technique for carbon dating brain cells, based on the rise in atmospheric radiation from the testing of nuclear weapons during the Cold War.

This testing resulted in a large rise in world-wide levels of environmental radiation, peaking in the mid-1960s. Because this radiation was absorbed via CO₂, the decay of radioactive carbon in the DNA of neurons can be used to date when these cells were ‘born’.

The study, led by neuroscientist Kirsty L. Spalding, examined the age of neurons in the occipital cortex – an area at the back of the brain important for the visual system.

The researchers found that the cells in this area were as old as the people studied, suggesting that new neurons are not created there.

Until a few years ago, it was thought that humans did not grow new brain cells after birth. It was discovered, however, that neurons regenerate in an area of the brain called the hippocampus, a structure known to be crucial for memory.

It is still unclear whether other areas of the brain regenerate, although this study suggests that, in the occipital lobe at least, neurons are not created anew.

Link to summary of study ‘Retrospective Birth Dating of Cells in Humans’.

The New York Times has an article on people who experience musical hallucinations.

This form of hallucination is interesting, because they are often the only unusual experience a person will have, unlike in psychosis, where hallucinations may be part of a range of anomalous beliefs and experiences.

Patients reported hearing a wide variety of songs, among them “Don’t Cry for Me Argentina” and “Three Blind Mice.” In two-thirds of the cases, the music was religious; six people reporting hearing the hymn “Abide With Me.” Dr. Aziz believes that people tend to hear songs they have heard repeatedly or that are emotionally significant to them.

Neurologist Tim Griffiths has been brain scanning people who experience these hallucinations. He has found that similar areas of the brain are active when a person is hallucinating music, compared to when they are actually listening to music, except for an area called the primary auditory cortex. This is the area of the brain just behind the ears, and is responsible for the initial processing of sounds.

Interestingly, musical hallucinations are often triggered by deafness.

These music-processing regions may be continually looking for signals in the brain that they can interpret, Dr. Griffiths suggested. When no sound is coming from the ears, the brain may still generate occasional, random impulses that the music-processing regions interpret as sound. They then try to match these impulses to memories of music, turning a few notes into a familiar melody.

Link to reg free New York Times article on musical hallucinations (originally via BrainBlog).

UPDATE: There’s a good piece by Carl Zimmer on musical hallucinations here.

Science News has a major article discussing sleep paralysis, the state in which a person can wake, but remains in the paralysed state used to stop movements during dreaming.

Sleep paralysis, sometimes called ‘awareness during sleep paralysis’, to distinguish it from the normal muscle inhibiting function of REM sleep, is now attracting a substantial amount of research.

One paper by researchers Katharine Holden and Chris French (PDF) even suggested that some ‘alien abduction’ experiences may be due, in part, to terrifying sleep paralysis episodes.

Little is known, however, about the exact brain mechanisms which control sleep paralysis (although parts of the brain stem are known to be important) meaning it is has traditionally been difficult to make educated guesses about why paralysis sometimes remains after waking.

Link to Science News article ‘Night of the Crusher’

ABC Radio’s All in the Mind has a special on the neuroscience of orgasm and the use of brain scanning in understanding this complex event.

The programme focuses on work being carried out by a Dutch team, who are now one of a number of research centres who are studying the neuroscience of orgasm and sexual response after it has been neglected for so many years.

Their work has been reported on Mind Hacks before (here and here) but this includes an interview with the lead researchers and commentary from a number of other experts.

mp3 or realaudio of programme audio.
Link to programme transcript.