Online guide to fault-finding the nervous system 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

Brain re-wires for object recognition

kourtzi.jpgOpen-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.

Cannabis and psychosis: The evidence

cannabis_leaf.jpgThe 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.

Philosophy and limb amputation

darklit_arm.jpgAustralian 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.

Maths ability without language skills


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’.

2005-06-24 Spike activity

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.

Evidence for ‘grandmother cells’

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.

halle_berry.jpgQuiroga 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
Link to study abstract.