Swimming with dolphins helps depression

dolphin.jpgChristian Antonioli and Michael Reveley at the University of Leicester recruited 30 mildly or moderately depressed people via adverts in America and Honduras. They allocated half of them to a two week course of swimming with dolphins in Honduras and the other half to two weeks of snorkelling and having fun in the sea without dolphins. Afterwards they found the participants who swam with dolphins had recovered from their depression significantly more than the control group. Seventy-seven percent of the dolphin group no longer met the threshold for depression on the Hamilton scale compared with 25 per cent in the control group.

The researchers said “The echolocation system, the aesthetic value, and the emotions raised by the interaction with dolphins may explain the mammals‚Äô healing properties”.

The findings support the concept of biophilia – the idea that “human health and wellbeing are strictly dependent on our relationships with the natural environment”. The term was first coined by Erich Fromm but has since been championed by and become associated with E.O. Wilson.

The dolphins weren’t available to comment.

Link to the study published in BMJ

Link to dolphin swimming holidays

Dijkstra on thinking machines

The great computer scientist Edsger Dijkstra on artificial intelligence and thinking machines:

John von Neumann speculated about computers and the human brain in analogies sufficiently wild to be worthy of a medieval thinker and Alan M. Turing thought about criteria to settle the question of whether Machines Can Think, a question of which we now know that it is about as relevant as the question of whether Submarines Can Swim.”

Link to ‘The threats to computing science’ by Edsger Dijkstra.

Vibrators shrink self-perceived waistline

Ehrsson_diagram.jpgIf using vibrators to shrink your waistline makes you think of spam email, you may be surprised to find out it’s the basis of a fascinating neuroscience experiment published in open-access science journal PLoS Biology.

The study relies on an unusual effect called the Pinocchio illusion, which occurs when a vibrating sensation is applied to the outside muscle on one of the body’s joints. This causes a feeling of the joint closing, when in fact it remains in the same position.

This feeling of movement can conflict with other bodily sensations, and can produce the unusual feeling that body parts are becoming warped or elongated, just like Pinocchio’s nose.

In Ehrsson’s experiment, they applied a vibrating sensation (the blue boxes in the diagram) to the back of each wrist, which gave the false impression that the hands were moving in towards the legs.

While this was happening, Ehrsson and his team brain-scanned the participants to detect active brain areas, and compared conditions where participants were touching vs not touching their legs; and where the vibration was applied to the joint muscles vs another area on the hands.

Crucially, only in the condition when the participant’s hands were touching their legs and the wrist joint muscles were being vibrated, did it feel as if their waste was shrinking to accommodate the illusory movement.

The team found that the strength of the illusion was associated with activity in areas of the left parietal lobe, which are known to be involved in creating the sensation of body shape, also called ‘body image’.

The study suggests that the brain generates body image by making a best guess from the incoming tactile information.

In other words, because the wrist jounts were providing ‘false’ information – indicating that the hands were moving through space occupied by the legs – the brain simply ‘guessed’ that the waist must be smaller to make sense of the discrepancy.

If you want to try this effect at home, a couple of vibrating sex toys are probably your best bet. If you don’t have any, now’s your chance to freak out your local sex shop by asking them to recommend the best dildo for cognitive neuroscience experiments.

Link to study summary.
Link to full text paper.
Link to write-up from nature.com
Link to write-up from BBC News.

Newsweek on society, neuroscience and anorexia

white_scales.jpgThe cover story in December 5th’s Newsweek is available online and tackles the science and treatment of anorexia, focusing particularly on why it seems to be increasingly prevalent in children as young as eight.

At a National Institute of Mental Health conference last spring, anorexia’s youngest victims were a small part of the official agenda‚Äîbut they were the only thing anyone talked about in the hallways, says David S. Rosen, a clinical faculty member at the University of Michigan and an eating-disorder specialist. Seven years ago “the idea of seeing a 9- or 10-year-old anorexic would have been shocking and prompted frantic calls to my colleagues. Now we’re seeing kids this age all the time,” Rosen says. There’s no single explanation for the declining age of onset, although greater awareness on the part of parents certainly plays a role. Whatever the reason, these littlest patients, combined with new scientific research on the causes of anorexia, are pushing the clinical community‚Äîand families, and victims‚Äîto come up with new ways of thinking about and treating this devastating disease.

Unfortunately, the article has a somewhat oversimplified account of psychiatrist Walter Kaye’s recent research review and hypothesis about anorexia: that starvation might be a response to a disturbed serotonin system, particularly to high levels at areas in the brain with the serotonin 5HT1A receptor – a system particularly linked to anxiety and obsessiveness.

Starvation might be a response to these effects, as it is known to lower trytophan and steroid hormone metabolism, which, in turn, might reduce serotonin levels at these critical sites and, hence, ward off anxiety.

Importantly, the effects on serotonin levels are often restricted to certain brain areas. Furthermore, studies on a different type of serotonin receptor, the 5HT2A, actually suggest a decrease in serotonin activity at this type of receptor.

Kaye also suggests that disturbance to the serotonin system may arise owing to a combination of genetics, puberty-related hormone changes, stress and cultural pressures – not just a “brain disease”, as one psychiatrist is quoted as saying.

The article does, however, report moving accounts of individuals and families affected by the condition, and contains links to a podcast, including interviews with clinicians and researchers.

Link to article ‘Fighting Anorexia: No One to Blame’ (via PCSD&A).
Link to abstract of Kaye and colleagues article on serotonin and anorexia.

Walking zombie syndrome

wide_bw_eye.jpgAntonio Melechi explores one of the bizarre corners of the medical literature in his book Fugitive Minds (p211, ISBN 0099436272):

In 1979, the Journal of the Tennessee Medical Association announced that the ‘Walking zombie syndrome’ – a condition in which depression and withdrawal led individuals to unconsciously believe that they were dead – was on the increase. Illness, coma, high fever, operations performed under partial anaesthesia, and bereavement were, it claimed, just some of the situations through which a ‘death suggestion’ could be unwittingly assimilated.

Fortunately, there was, according to the hypnotherapists who ‘discovered’ the condition, one simple and effective cure: age regression. By returning patients to the event which triggered the ‘death suggestion’, the ‘symptoms of death’ could, it was claimed, be at once relived and remedied.

Although most physicians remained unaware of the diagnosis or treatment, the pseudo-illness continued to claim factitious casualties. By the late 1980s, the United States had apparently overtaken Haiti as the zombie capital of the world. According to one estimate, there were ‘thousands of walking zombies on the streets of every city’.

Link to PubMed entry for ‘The Walking Zombie syndrome in depressive disorders’.
Link to review of ‘Fugitive Minds’.

All in the Mind on sexual desire

girl_eyes_right.jpgABC Radio’s All in the Mind starts a four part series today on the emotional brain, with the first in the series examining the complexity of sexual desire.

Psychologists Dylan Evans and Doris McIlwain discuss whether we have one sex drive or many, and how it influences and gets tangled up with our other thoughts, desires and behaviour.

Despite the portrayal in some of the media, what emerges is that sexual desire is a rich and complex human motivator.

mp3 or realaudio or programme audio.
Link to transcript.

Did Mohammed have epilepsy?

Mohammed, founder of Islam, is often described as having epilepsy. He’s even described as such on epilepsy information site epilepsy.com. The historical basis for such claims are almost certainly false, however, and first stem from a historian writing almost 200 years after the Prophet’s death.

The myth has been most comprehensively debunked by the respected American historian of medicine Owsei Temkin in his book The Falling Sickness: This History of Epilepsy from the Greeks to the Beginnings of Modern Neurology (ISBN 0801848490). To quote from p153…

As is to be expected, the positive bias of Islam was countered by an opposite bias in the Christian world. As to the origin of the diagnosis “epilepsy”, everything points to Christian Byzantium, an empire that was no only hostile to Islam but at frequent war with the Arabs. Less than 200 years after Mohammed’s death, the Byzantium historian Theophanes (died about 817) told a story which was bound to make Mohammed appear and fraud and to discredit the belief in his divine mission.

According to Theophanes, Mohammed had the disease of epilepsy. And when his wife noticed it, she was very much grieved that she, being of noble descent, was tied to such a man, who was not only poor but epileptic as well. Now he attempts to soothe her with the following words: “I see a vision of an angel called Gabriel and not being able to bear the sight of him, I feel weak and fall down.” But she had a certain monk for a friend who had been exiled because of his false faith and who was living there, so she reported everything to him, including the name of the angel. And this man, wanting to reassure her, said to her: “He has spoken true, for this angel is sent forth to all prophets”. And she, having received the word of the pseudo-prophet, believed him and announced to the other women of her tribe that he was a prophet. (Theophanes, 1007, Chronographia, vol. 1, p334)

The is the story which was accepted by Western historians, theologians and physicians. The story has all the earmarks of religious and political propoganda. Hence it was repudiated by Gibbon as “an absurd calumny of the Greeks”.

PDF of Owesei Temkin’s obituary.