Category: Inside the Brain

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.

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.

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.

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.

Slate has an insightful article on the possible legal consequences of developments in the neuroscience of consciousness, including implications for issues such abortion and right-to-die cases.

It also discusses some of the history and disparities between how different groups define life and death.

Religious conservatives want the law to define life as the existence of a single living cell containing human DNA. Yet their Schiavo campaign bolstered both the acceptance of consciousness as the boundary between life and death and the authority of neuroscience to measure it.

Link to article ‘The Consciometer’ via Metafilter.

New Scientist is reporting that IBM will attempt to simulate the “entire brain” in collaboration with the Swiss Brain Mind Insititute using a specially modified computer system dubbed ‘Blue Brain‘.

It seems from the news reports that the system will attempt to simulate the physical properties of individual neurons and their connections – a science known as neuroinformatics. Both the New Scientist story, and another from Business Week, are a little light on detail however.

They both suggest that an initial project will be to simulate the structure and function of neocortical columns – the three dimensional, highly interconnected layers of neurons, famously found to be an essential part of the visual cortex.

Although impressive, this seems a far cry from simulating the ‘entire brain’, which would involve simulating 100 billion neurons and 100 trillion synapses in real-time.

This assumes, of course, there is a good enough understanding of how each neuron and synpase works – a science which is still very much in development.

The project is long-term however (a decade is mentioned), so hopefully it will allow for some important developments, even if physically simulating the entire brain might be a little far fetched – even in the near future.

Link to New Scientist article ‘Mission to build a simulated brain begins’.
Link to Business Week article ‘Blue Brain: Illuminating the Mind’.

Online media journal Stay Free! Daily takes a critical look at a recent newspaper report that anorexia is ’caused’ by a brain dysfunction rather than pressure from society.

The story is based on a recent paper from a research group led by psychiatrist Bryan Lask.

Their study found decreased blood flow in a variety of brain areas in a group of adolescents with anorexia, but found that this was not actually linked to any features of the eating disorder, contrary to what the newspaper headline suggests:

There appears to be no association between this reduction in blood flow and cerebral dominance, nutritional status, length of illness, mood, or eating disorder psychopathology. However, there is a significant association between reduced blood flow and impaired visuospatial ability, impaired complex visual memory, and enhanced
information processing.

This suggests that the underlying brain changes in anorexia do not directly affect eating, food or body perception – they are much more general.

How then, does this lead to anorexia ? Lask and his team suggest that a part of the brain called the limbic system might be involved, and that:

Within specific setting conditions such as sociocultural pressures to be thin and a driven and perfectionist personality, the limbic system imbalance may be triggered by such factors as puberty, dieting, weight loss, and various stressors.

In other words, without the pressures from society and a ‘perfectionist personality’, people who have these differences in brain function are unlikely to become anorexic. People who have both therefore, are at the greatest risk of wanting to starve themselves.

A recent study published in the British Journal of Psychology gives us a clue as to what might cause this pressure to be thin.

Researchers showed participants pictures of female bodies, digitally altered to be wider or more thin than average, and then asked them to pick out most attractive body shapes from a range.

After being shown thin bodies, participants tended to pick thinner bodies as the most attractive.

The authors argue that perception of attractiveness and beauty are relative to our experience of the most common body shape, suggesting that the promotion of thin bodies in the media may distort our idea of attractiveness by affecting the ‘data’ on which we judge normality.

Link to Stay Free! article.
Link to abstract of anorexia / neuroscience study.
Link to body shape study.

TheBrainFreeze.com is a website dedicated to ‘ice cream headaches’, a condition sometimes known as ‘brain freeze’. It hosts a short yet strangely compelling movie of people causing headaches in themselves with slushed ice drinks.

A 1997 article in the British Medical Journal explained why cold things cause headaches, and describes some good old-fashioned self-experimentation in the service of science.

Experimenting on himself, Smith characterised the features of the headache. Applying crushed ice to the palate, he found that ipsilateral temporal and orbital pain developed 20-30 seconds later. Bilateral pain occurred when the stimulus was applied in the midline. The headache could be elicited only in hot weather; attempts to reproduce the pain during the winter were unsuccessful, even with use of a cold stimulus of the same temperature.

Luckily for ice creams fans, the article shys away from medical scaremongering, recommending that “ice cream abstinence is not indicated”.

Link to TheBrainFreeze.com
Link to BMJ article on Ice cream headache.

New Scientist have put their cover article on brain optimising technologies online – which covers everything from nutrition to neurofeedback.

Their story, 11 steps to a better brain, looks at the science behind techniques that have been shown to boost mental performance.

Some of the techniques are fairly common-sense approaches, like sleeping well and exercising, although the article explains exactly how these might affect thought and behaviour.

Others are a little more controversial and potentially hazardous, such as the use of stimulant drugs like modafinil and methylphenidate.

One particularly interesting part however, is the mention of mental training techniques to boost wider cognitive performance.

Using functional magnetic resonance imaging (fMRI) brain scans, they measured the brain activity of adults before and after a working-memory training programme, which involved tasks such as memorising the positions of a series of dots on a grid. After five weeks of training, their brain activity had increased in the regions associated with this type of memory.

Perhaps more significantly, when the group studied children who had completed these types of mental workouts, they saw improvement in a range of cognitive abilities not related to the training, and a leap in IQ test scores of 8 per cent

Interestingly, similar techniques are now being applied to traditionally hard-to-treat conditions such as schizophrenia that have been shown to have a positive impact on cognitive performance and brain function.

Link to 11 steps to a better brain.

21st May is morphine’s 200th birthday – we’ve had the pain-killing poppy extract for two centuries and it has had a massive impact on medicine. Strangely, one of the most important effects was found when it was never used…

Anaesthetist Henry Beecher was involved in treating wounded soldiers during World War II. During particularly fierce fighting morphine supplies ran out. In desperation, Beecher used saline solution instead.

The soldiers reported that the fake ‘morphine’ eased their pain – Beecher had discovered the placebo effect.

Inspired by his experiences, Beecher ended up writing one of the most influential papers in medicine The Powerful Placebo, leading to placebo-controlled trials being used as standard in the testing of new medicines.

Chemist and psychedelic compound researcher Alexander Shulgin reports a similar experience in his book PiHKAL, when during his time in the Navy, he needed an operation for a damaged thumb.

…it was this that started me on my career as a psychopharmacologist. I was told that the white “drug” which was undissolved at the bottom of my orange juice glass, and which had finally plopped me over the line from being an alert and defensive surgery candidate to being comatose subject available to any and all manipulation by the operating physician, was nothing but undissolved sugar.

For those interested in the history, psychology and neuroscience of the placebo effect, you could do a lot worse than check out Placebo by cognitive scientist and Mind Hacks contributor Dylan Evans.

And for those still hungry for more about morphine, this is part of birthday celebrations hosted by Kelly from Time to Lean blog, where various authors are contributing morphine related posts. Party on.

A kuro5hin.org article on ‘Demystifying depression‘ gives an excellent account of the experience of depression, but uncritically repeats some common assumptions about the condition – namely that it is a ‘physical illness’ caused by ‘low serotonin’.

Despite the familiarity of these claims, both are problematic.

Continue reading “Is depression a brain disease ?”

An article in the schools section of the Education Guardian discusses the growing evidence for a link between fatty acids, brain function and behaviour.

The story focuses on the potential effects on visual problems, dyslexia and difficulties with attention.

The writer does seems to get a little carried away however, when he questions whether such findings “challenge the very notion of free will”:

Revealing as it does that mood, behaviour and achievement are affected by whether the brain has enough of the right kind of nutrients to function properly, it throws into doubt how far anyone… can actually control their behaviour.

Perhaps we are all being brainwashed by breakfast cereal ?

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Link to article Why it’s time we faced fats