I’m putting together my lectures for the visual perception part of PSY101 (which I’m teaching in a few weeks). I was so proud of this particular slide that I had to share it:
Yesterday’s Nature contains an intriguing short report of how stimulating part of the brain during neurosurgery induced the feeling that a shadowy version of the patient’s body had appeared and was mirroring the patient’s movements.
The patient was undergoing routine neurosurgery to examine the brain, prior to more serious neurosurgery to treat otherwise untreatable epilepsy.
It is not uncommon for patients to volunteer to take part in simple neuroscience experiments during these procedures.
Patients have to be awake for part of the neurosurgery anyway because the surgeons probe the brain to make sure they avoid removing any areas essential for language, memory and so on.
The experience of feeling or seeing a double or your own body is called autoscopy or heautoscopy.
In this case, a team of researchers led by neuroscientist Shahar Arzy managed to induce this experience by stimulating an area of the brain called the left temporoparietal junction.
This is the area on the left side of the brain where the temporal lobe and parietal lobe meet (see the pink arrow in the image on the left).
This is not the first case of this kind. The Nature report is from the lab of Olaf Blanke which has reported a number of cases of this condition, either owing to brain injury, epilepsy, or induced by brain stimulation.
In a 2004 paper published in Brain, Blanke’s team reported on a number of patients who experienced this phenomenon, including one who said “I see myself lying in bed, from above, but I only see my legs” when her brain was also stimulated in the left temperoparietal junction.
(NB: This paper is available on Cortex’s website but because their site is such as mess, you can’t link to it directly and you have to use Explorer to navigate. Isn’t progress great?)
The temporoparietal junction might be significant as it is thought to process and hold representations of the body and its relationship to external space.
One interesting aspect of the Nature paper is that the patient reported that her double was unpleasant and seemed to have somewhat malign intentions:
Further stimulations (11.0 mA; n=2) were applied while the seated patient performed a naming (language-testing) task using a card held in her right hand: she again reported the presence of the sitting “person”, this time displaced behind her to her right and attempting to interfere with the execution of her task (“He wants to take the card”; “He doesn‚Äôt want me to read”).
The authors suggest they may have found evidence for the mechanism behind ‘delusions of control’ or ‘passivity symptoms’ usually linked to schizophrenia.
These are experiences or beliefs that the body and / or mind is being controlled by external forces.
However, not all patients with autoscopy report their experiences as malign, and it may be that the effect of the anaesthetics (known to induce paranoia in some), epilepsy (also linked to risk for psychosis) or the stress of the operation, may have given an unpleasant or malign twist to the experience which might not be directly linked to the disruption of the proposed brain mechanism itself.
The paper is also discussed on Nature’s news service.
Link to abstract of Nature study.
Link to Nature News write-up.
Link to full-text of 2004 Brain paper.
Link to full-text of Journal of Neuroscience paper on tempororparietal junction, body image and self .
London’s Victoria Miro Gallery is currently hosting an exhibition by Stephen Willats entitled From My Mind to Your Mind.
Willats uses his artwork to explore how people makes sense of the world, particularly in terms of how we operate and interact as individuals in society.
Particularly focusing on urban life, he often critiques the way in which modern city-based living affects not only the practical aspects of life, but also how we begin to perceive the world through this urban lens.
The Tate Modern recently hosted a discussion with Willats on his work, and have made the podcasts available online.
The exhibition at the Victoria Miro gallery runs until the 30th September.
Quick links from the past week in mind and brain news:
Memory difficulties in older people may signal brain tissue loss in some, reports New Scientist.
GNIF Brain Blogger gives a rundown on the DSM – the diagnostic manual for psychiatric disorders.
The New York Times discusses the psychology of one of the most widely-known but scientifically neglected human motivations – fame.
The Neurophilosopher digs up some beautiful neuroanatomy drawings from the 14th to the 19th centuries.
I don’t know why we don’t just have a permanent feed to Developing Intelligence…
ABC Radio’s All in the Mind discusses the Journey Through Madness – a family’s story of their experience of mental illness.
The University of Wisconsin Medical School have an online video series that shows a dissection of a human body, including special sections on the brain and spinal cord, all expertly narrated by the professors in the department.
There is no better way of learning anatomy than seeing a dissection for yourself (I have fond memories of passing round a freshly removed circle of Willis with my fellow MSc students) and the online video series is an excellent introduction.
The first thing you notice is how some parts of the dissection process are so undelicate. The body is very strong, and it can take quite some force to remove certain parts.
In the brain dissection, the anatomist has to use some significant leverage (and a surgical chisel) to separate the skull from the dura mater – the tough plasticy sheet covering the brain.
The dissection itself is quite medical, in that it tends to focus on the gross (large scale) anatomy of veins, arteries and cavities, rather than on the sort of areas of most interest to cognitive neuroscientists – mainly the internal structure of the cortex.
Nevertheless, if you want a good ‘rough guide’ to the brain, this is as good a place to start as any.
‘The God Delusion’, Richard Dawkins’ forthcoming book on religion, is “incurious, dogmatic, rambling and self-contradictory” according to Andrew Brown (author of the Darwin Wars), writing in Prospect magazine.
To a psychologist (or anyone taking a scientific approach to religion), what’s particularly of interest, is not so much whether or not God exists, but why so many people are believers, even today, when evolutionary theory means there’s no longer any need to invoke a designer to explain life’s complexity. But according to Brown’s scathing review, Dawkins utterly fails to offer any fresh insight into this question. “Thinking a bit was once what Dawkins was famous for. It’s a shame to see him reduced to one long argument from professorial incredulity”.
Dawkins is developing a somewhat legendary reputation for being anti-religion, a trend he has encouraged – he titled a collection of his essays published a few years ago ‘The Devil’s Chaplain’. Perhaps his most notable and controversial exposition on the subject was an article he wrote for the Guardian newspaper, just days after 9/11, in which he lamented the devaluing effect of religion on human life, and characterised the terrorists responsible as “testosterone-sodden young men too unattractive to get a woman in this world” but “desperate enough to go for 72 private virgins in the next”.
UPDATE: Andrew Brown debates his review and Dawkins’ book with science writer Dan Jones and others, at Jones’ blog – the proper study of mankind.
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