NeuroExam.com explains the standard examination conducted by neurologists to check the functioning of the nervous system, complete with video.
The website is intended to accompany a book called Neuroanatomy through Clinical Cases, written by Professor Hal Blumenfeld.
It works pretty well on its own however, and gives a fascinating insight into exactly what neurologists are doing as they push, tweak, tap and prod their way through an assessment.
It also shows that surprisingly simple tests can tell us a great deal about the nervous system.
For example, asking someone to stand still with their eyes closed and giving them a slight push (something known as the Romberg Test) can help determine whether there is damage to the proprioceptive or vestibular system.
Link to neuroexam.com
Open-access science journal PLoS Biology reports on research looking at how the brain handles object recognition among the clutter of the everyday visual world.
Researchers, led by neuroscientist Zoe Kourtzi, asked participants to detect objects hidden in various background images, whilst being scanned in an fMRI scanner.
“The authors found that subjects demonstrated an increased number of correct responses for shapes they encountered during the training sessions, regardless of the type of background the shapes were presented on. By contrast, the fMRI responses differed dramatically, depending on whether the surroundings made the shapes easy or difficult to detect.”
“These results demonstrate that the ability to learn to detect novel shapes is independent of the degree of difficulty, but suggest that the brain employs different mechanisms of perceptual learning depending on whether the objects stand out from their surroundings, or are obscured by them.”
Link to summary of study.
Link to full-text of study.
The BBC recently aired an edition of current affairs programme Panorama on cannabis and psychosis. If you missed it, they’ve summarised current research on possible links between cannabis and severe mental illness on their website.
Although most people who smoke cannabis will not develop psychosis, the evidence for a link is now growing. The risk seems greater if users start younger and use in greater amounts.
It has recently been reported that those with forms of the COMT genes, known as a val-val combination, are particularly at risk.
The BBC website also has a page for those wanting more information or support concerning cannabis use and / or mental health.
Links to BBC webpages:
* Cannabis and psychosis: the key research.
* Interview with Dr Philip Robson on cannabis and psychosis.
* Interview with Dr Robin Murray on cannabis and our genes.
Australian philosophers Tim Bayne and Neil Levy have argued that people who want to be amputees should be allowed to have elective amputations, even if they have healthy limbs.
This unusual desire has been labelled ‘body integrity identity disorder‘ or BIID by psychiatrists.
It has caused much ethical concern among doctors who are bound by the hippocratic oath to ‘do no harm’, but are faced with some patients wanting healthy limbs removed.
Bayne and Levy argue that such people are not “globally irrational”, and should be considered to have the capacity to make such decisions about their body.
Tim Bayne has previously done work on delusions and rationality, and has extended this analysis into applied ethics.
Link to story from ABC News.
Link to study abstract.
Link to Tim Bayne’s homepage with full-text publications.
Scientific American reports on three individuals who retained remarkable mathematical skills after brain damage that left them unable to use language to communicate.
Varley and her colleagues found that although the subjects could no longer grasp grammatical distinctions between, say, “The dog bit the boy” and “The boy bit the dog,” they could interpret mathematical formulas incorporating equivalent structures, such as “59 – 13” and “13 – 59.”
Although subjects easily answered simple problems expressed in mathematical symbols, words continued to stump them. Even the written sentence “seven minus two” was beyond their comprehension. The results show quite clearly that no matter how helpful language may be to mathematicians–perhaps as a mnemonic device–it is not necessary to calculation, and it is processed in different parts of the brain.
This suggests that maths ability does not necessarily rely on written or spoken language to give calculations logical order and coherence.
Link to Scientific American story ‘Math without Words’.
Quick links from the past week in mind and brain news:
Insightful, sardonic and often sharply witty blog, detailing the trials and tribulations of a mental health nurse (via PsyBlog)
Website from the Boundary Institute has online ‘Psi’ tests to look for extransensory abilities.
Raj Persaud takes us inside the mind of an adulterer, discussing the psychology of infidelity.
Violent video games activate similar brain areas to real violence.
The smell of male pheromones makes men more likely to opt for male lifestyle magazines than other titles.
Women are more afraid of dentists than men, research shows. Must be all those men’s lifestyle magazines in the waiting room.
Narcissicists seem better able to handle trauma than others.
Sex psychologist Petra Boynton critical of attempts to brain scan orgasm, but clarifies her comments after feedback.
Metafilter on what you think about when you’re not thinking about much.
This week’s edition of the science journal Nature reports that single brain cells may be specialised for recognising specific faces.
This is an interesting finding, as it provides support for a derided hypothesis known as the ‘grandmother cell‘ theory, that was thought up to ridicule attempts to reduce human experience down to smaller and smaller components of the brain.
Neuroscience often develops by trying to understanding how smaller parts of the brain support larger processes. Bologist Jerry Lettvin argued that we can’t expect everything to reduce down to the smallest level, as some things will be distributed across the brain.
It is unlikely, he argued, that there is a single brain cell to represent each person we know, a neuron that is active when we see our grandmother, for example.
This has since been used as an argument against any theory that is seen as over-simplifying how things are represented in the brain.
But now, a team led by neuroscientist Rodrigo Quian Quiroga has identified neurons which do seem to be active for individual faces.
He implanted harmless electrodes into the temporal lobes of volunteers undergoing surgery for epilepsy.
Quiroga then showed the participants pictures of famous faces, and discovered some cells were only active for individual faces in the set – Halle Berry, or even members of The Simpsons.
Of course, it’s impossible to say whether these cells are truly selective for an individual face out of all the ones a person may know, but this level of selectivity is a great surprise for those who thought individual cells would be active for very general features of the visual world.
Link to write-up from nature.com
Link to study abstract.
Cognitive Daily has an elegant summary of research on why we don’t remember the first years of life. The results suggest that it may be because young children lack the language resources to support the necessary memories.
I would be tempted to quote some of the post here, but its described so succinctly its probably best just to read the original.
Link to ‘Why do we forget our childhood?’ from Cognitive Daily.
Julian Beever is a street artist who takes advantage of the way the brain understands the world to create some amazing artwork.
The brain works out our 3D experience of the world from the 2D light patterns that fall onto our retina at the back of the eye.
This process takes advantage of many of our implicit assumptions of the world, such as the fact that textures will fade as they go farther away, parallel lines will tend to converge in the distance and that objects will seem larger the closer they are.
Julian Beever’s art uses a knowledge of these processes, so when seen from a certain angle, the pictures fool the visual system’s inbuilt processes to produce a false sense of depth.
When seen from an alternative angle, the illusion breaks-down, and it’s possible to see how the artwork was created.
There’s plenty more examples of this amazing effect on Julian’s pages that are well worth checking out.
Links to Julian Beever’s homepage and street art page.
PDF of notes on ‘An Introduction to Visual Perception’.
Finally, someone has done a neuroimaging study of the female orgasm.
Although the paper from this study has not been published yet, if the conference reports are anything to go by, it may be the first functional neuroimaging study of orgasm in healthy human females.
My only caveat is the rather random way this story is being reported (e.g. ‘Brain scans detect fake orgasms’) and the seemingly odd quotes from the researcher involved (from a BBC News story):
Professor Holstege said: “Women can imitate orgasm quite well. But with genuine orgasm”, he said: “What we see is an extreme deactivation of large portions of the brain hippocampus and especially the emotional parts involved with fear… And if you are fearful, it is very hard to have sex. It’s very hard to let go.” He said this was useful for men to know. “When you want to make love to a woman, you must give her the feeling of being protected.”
If reported correctly, Prof Holstege seems to have gone from a discovery about a reduction in brain activity (possibly based on a weak clich√© that the amygdala circuit is the ‘fear’ part of the brain) to advice on ‘how to make love to a woman’.
Come again ?
Link to story from newscientist.com
Link to story from BBC News.
The Arizona Daily Star is reporting that doctors are being warned that some general anaesthetics are associated with sexual dreams which some people may remember as real.
Although it is almost impossible to verify how often sexual hallucinations occur, some studies indicate it happens in 1 percent to 3 percent of anesthetized patients, Strickland said. With some anesthetic drugs – such as ketamine or propofol – the incidence is up to 5 percent.
Just why it happens is not well understood. But the risk is higher under lighter, sedating anesthesia than under deep anesthesia, doctors have found.
Link to article from Arizona Daily Star (via BoingBoing)
Links one and two to cases on PubMed.
Research suggests that the scent of grapefruit causes men to judge women up to six years younger than their chronological age.
Let’s see if the evolutionary psychologists can come up with an explanation for this one!
Link to write-up from WebMD.com
Link to story from ScienceDaily.com
Numenware is a recently re-launched blog that covers the developing world of neurotheology – the neuroscience of spiritual experience and belief.
The site is authored by Bob Myers, who manages to approach the subject in a critical but non-dogmatic way and avoids scoring easy points on complex topics.
Some of my favourites include a post musing about a neurological basis of average age of enlightenment, one on developmental neurotheology, and note on the possible adaptive value of near-death experiences.
Link to numenware.com
A study published online by the British Medical Journal suggests that people with epilepsy or a family history of epilepsy may be more likely to develop schizophrenia or psychotic symptoms.
Researchers from the University of Aarhus analysed the records of 2.27 million Danish people, and found the risk of schizophrenia-like psychosis slightly raised in people with epilepsy, or those with family members who have epilepsy.
The absolute risk still remains small however, as only 1.5% of the people with epilepsy went on to develop psychosis.
The significance of these findings are in the suggestion that epilepsy and psychosis may have some common genetic influences. This influence is likely to be complex however, as demonstrated by a curious interaction.
The study found that people with epilepsy were more likely to develop psychosis if there was no family history of psychosis or schizophrenia.
Link to story from Yahoo News.
Link to study abstract.
UPDATE: The BMJ have just published a ‘rapid response‘ I submitted about the article’s findings.
A research team has announced that they have developed a brain imaging technique to detect the early stages of Alzheimer’s disease with a claimed accuracy of 78%.
The technique, named HipMask and developed by neuroscientist Lisa Mosconi and her team, uses a brain scanning technique called PET. This involves injecting weakly radioactive glucose into the blood and measuring where it accumulates in the brain.
Glucose is used as ‘fuel’ by the brain, so brain activity in a particular location can be inferred from measuring the levels of radioactivity.
Mosconi’s team have discovered that poor levels of activity in a brain area called the hippocampus, a crucial memory area, predict the onset of Alzheimer’s disease up to 9 years before standard diagnosis.
Because the hippocampus is small and hidden deep within the brain, measuring its activity has been traditionally considered quite hard, as it produces a relatively weak signal.
Mosconi’s team overcame this problem by also using an MRI scan of the brain, which gives a more accurate internal picture, to complement the PET scan, which gives a clearer measure of hippocampal function.
Link to write-up of study from from Eureka Alert.
Link to story from Yahoo News.
Link to study abstract.
Jack El-Hai, the biographer of surgeon and early lobotomy enthusiast Walter Freeman is interviewed on ABC Radio’s In Conversation.
El-Hai has written The Lobotomist: a maverick medical genius and his tragic quest to rid the world of mental illness, that follows Freeman’s life, and the history of psychosurgery – the use of brain surgery to attempt to treat mental disorder.
Freeman is now a controversial character, and many see his enthusiasm for doing literally hundreds of lobotomies as verging on abuse of vulnerable patients, whereas Freeman himself argued that his was an effective treatment for otherwise untreatable people.
One of Freeman’s most notable lobotomy patients was Rosemary Kennedy, sister of JFK – an episode El-Hai describes as “one of the worst” in Freeman’s career.
Realaudio or webpage of In Conversation on Walter Freeman.
Link to New Statesman review of El-Hai’s book.
Link to the book’s website with first chapter online.