New super low-power brain scans

Memoirs of a Postgrad has got a great write-up of a new low-power MRI machine, the technology that does most of the structural and functional brain scans. Even the smaller MRI machines need huge electromagnets, but this new technology uses magnets thirty thousand times weaker to image the brain.

In a standard MRI machine, a strong magnetic field is used to align the proton in each of the hydrogen atoms before using an RF pulse to knock them out of alignment. As they snap back into alignment with the magnetic field, they emit a signal which can be detected and used to create a 3D image. In the new version, the very small magnetic field isn’t enough to align the protons, so a short duration (1 second) magnetic pulse of slightly higher magnitude (30 millitesla).

The resulting signals are very small, so an array of highly sensitive magnetometers are used (so-called superconducting quantum interference devices, or SQUIDS). A hugely important additional advantage of using these SQUIDS is that they are also used in the MEG (magnetoencephalography) imaging technique. This potential for MRI and MEG using the same machine raises the intriguing possibility of producing simultaneous structural images (using the MRI) and brain activation maps (using the MEG).

Unfortunately, the use of SQUIDs dashes any hopes of making the machines much smaller.

The SQUID sensors need to be extremely cold (working at approximately -170 degrees C) and so are usually bathed in liquid nitrogen, meaning a huge insulated tank sits atop the scan area.

IEEE Spectrum magazine has an article with some images from the new type of scanner, which look pretty fuzzy at the moment, but apparently can better distinguish tumours in the brain and will undoubtedly become clearer as new software is developed.

Link to Memoirs of a Postgrad post.
Link to IEEE Spectrum article.

Polanski and the Professor

It was 1970, and a white Rolls Royce was gliding through the streets of London. Inside were the obviously disturbed Roman Polanski, the film director still reeling from the murder of his wife, and Richard Gregory, the legendary cognitive psychologist.

Polanski had discovered Gregory’s work on visual perception through his book Eye and Brain and decided he wanted to enlist Gregory’s help to create a 3D horror movie.

The movie was intended to be revolutionary, taking advantage of the brain’s perceptual quirks to make a truly disturbing visual experience.

They spent the week in Polanski’s office, actually the rear of his white Rolls Royce, discussing concepts, checking out studios and making plans.

In the end, their plans were too ambitious and were abandoned by Polanksi, who moved on to other projects.

Gregory remembers the episode well however, and discusses his meeting with Polanski, and the science behind their abandoned project, in an online audio recording.

Interestingly, Gregory also mentions that Polanksi also wanted to use the techniques they developed to make a 3D erotic movie.

Visual perception lectures would have never been the same again, much to the delight of generations of psychology students, but sadly, it remains only as a wonderful tale of an unlikely pairing.

The recording seems to be from a fantastic Polanski DVD box set that also contains his film Repulsion, notable for its portrayal of a young woman’s descent into a terrifying psychosis and the film’s use of perceptual distortion to communicate the experience to the viewer.

Link to audio of Gregory discussing his collaboration with Polanski.

Out on a phantom limb

ABC Radio National’s opinion programme Ockham’s Razor has an engrossing edition on how our perception and ownership of our body can break down after brain injury – leading to disorders where we think our limbs are someone else’s, where we feel there’s a phantom body behind us, or where we think we’ve been cloned.

The talk is by neuropsychologist John Bradshaw who specialises in understanding how the body is represented by the brain, including the experience of having feelings from an amputated phantom limb.

The talk is a little dense in places but more than worth the attention it needs, as the somewhat wordy sentences unpack into an evocative tour through the far reaches of some strikingly neurological syndromes.

One of the most unusual of these disorders is somatoparaphrenia.

While limb paralysis is not unusual after brain injury, in somatoparaphrenia the patient denies the limb is their own and often suggests that it is someone else’s, such as their husband’s, their doctor’s, or even a ‘dead’ limb that has been attached by people trying to trick them.

One of the earliest discussions of these phenomenon is in a 1955 paper on the personification of paralysed limbs. Rather wonderfully, the full text of the paper is available online.

Link to Ockham’s Razor on bodily integration, identity and brain injury.
Link to paper ‘Personification of Paralysed Limbs in Hemiplegics’.

Depression, antidepressants and the ‘low serotonin’ myth

Bad Science has a fantastic article on antidepressants and the widely-promoted but scientifically unsupported ‘low serotonin theory’ of depression.

Owing to a huge advertising push by drug companies, not only the ‘man on the street’, but also a surprisingly large numbers of mental health professionals (clinical psychologists, I’m look at you) believe that depression is linked to ‘low serotonin’ in the brain.

The only drawback to this neat sounding theory is that it is almost completely unsupported by empirical evidence or scientific studies.

Experiments that have deliberately lowered serotonin levels in the brain have found that it is possible to induce ‘negative mood states’ (usually milder and as short-lasting as a slight hangover), but these do not even begin to compare to the depths of clinical depression.

In terms of patients with the clinical mood disorder itself, not a single study has found a link to reduced serotonin.

Bad Science neatly reviews the science, and also discusses a new research study which chased up journalists that propagated the myth to ask for their sources.

Needless to say, none of them had any sound scientific basis for their claims.

This is not to say that antidepressants don’t help treat depression, (evidence suggests they do – although the effect is more modest than drug companies would have us believe), or that neurobiology isn’t important (by definition, if it’s a change in thought and mood, it’s a change in brain function).

If you’re interested in the history of how the ‘low serotonin hypothesis’ came to be thought up and then subsequently promoted, despite the lack of evidence, Professional Psychology: Research and Practice recently published a great article on the topic [pdf].

Link to Bad Science on the serotonin myth.
pdf of article on the history and popularity of the myth.
Link to excellent PLoS Medicine article on evidence and adverts.

Griefer madness

You know it’s a bad day when it starts raining penises during a media interview. Wired has an article on the ‘griefer’ subculture, sociopaths of the virtual world.

Essentially, they are virtual world vandals, or online versions of those local kids on the street who love shouting abuse and messing the place up.

Like most other aspects of human behaviour, antisocial behaviour transfers from the offline to the online world.

But like many subcultures on the internet, it is a new phenomenon in that people who would never normally get a chance to meet many others who share their socially unpopular beliefs, suddenly have access to a huge, distributed community of such people.

One of the most notorious ‘griefer’ attacks, before the term was even conceived, was described in the landmark article ‘A Rape in Cyberspace’, and describes an antisocial user taking over a text-based environment

It was one of the first pieces to convince people that internet interactions could have serious emotional effects, and is widely cited in the internet psychology literature.

The Wired article discusses the motivations (and even, the ‘philosophy’) behind these groups, as well as their impact on the increasingly commercial virtual worlds.

Link to Wired article on ‘griefer subculture’.

2008-01-25 Spike activity

Quick links from the past week in mind and brain news:

The fantastic Claudia Hammond explores the curious psychology of disgust on BBC Radio 4’s science programme Frontiers.

Advances in the History of Psychology notes the passing of Paul D McLean, creator the the “Triune Brain Theory“. Every time you hear the phrase ‘reptilian brain’, that’s McLean at work.

AI learns to play Ms Pac Man. Presumably, it will soon by driven insane by the annoying music.

To the bunkers! Charmingly wide-eyed transhumanists discuss the ‘singularity‘ – supposedly when computers will overtake the abilities of the human mind.

No really, to the bunkers! Israel intend to deploy an AI-controlled missile system that “could take over completely” from humans. Not that anyone would notice if it went bezerk I guess.

Neurophilosophy looks at a case of epilepsy triggered by hip-hop. As we noted back in October, the Beastie Boys created hip-hop triggered by epilepsy.

Dave Munger of the mighty Cognitive Daily reviews the new book by the Blakeslees on embodied cognition over at The Quarterly Conversation.

Which self-help books for depression do psychologists recommend for depression? PsyBlog looks at an interesting study on the most effective bibliotherapists.

A link between walking speed and mental quickness in the elderly is reported in an intriguing study covered by the BPS Research Digest.

The philosophy of friendship is discussed in a podcast from Philosophy Bites

Cognitive Daily examines the ‘remember / know‘ distinction, one of the most important ideas in long-term memory research.

The myth of the mid-life crisis? An article in The New York Times questions one of our most persistent cultural clichés.

The Frontal Cortex has an interesting meta-piece on whether neuroscience is being overly popularised.

Dr Pascale Michelon writes her first article as one of Sharp Brains expert contributors on neuroimaging and the ‘<a href="http://www.sharpbrains.com/blog/2008/01/23/looking-inside-the-brain-is-my-brain-fit/
“>cognitive reserve‘.

Scientific American’s Mind Matters blog discusses how to create out of body experiences in the lab.

Immanuel Kant, or can he? Fragments of Consciousness has a great post on philosophy teams.

So long, and thanks for all the fish, suckers

SciAm’s Mind Matters blog has a completely fascinating post on the common assumption that humans have the the most complex brain of all the animals. Compared to a whale, however, our brain is smaller and has even less cortical folds. Does that mean they’re smarter?

The article is by neuroscientist R. Douglas Fields and takes a comparative look at brain size, relation to body size, and function across the species.

It turns out, we’re perhaps not quite so special as we like to believe. Even on the ratio of brain to body size, humans are beaten by the humble tree shrew.

We humans pride ourselves on our big brains. We never seem to tire of bragging about how our supreme intelligence empowers us to lord over all other animals on the planet. Yet the biological facts don’t quite square with Homo sapiens’ arrogance. The fact is, people do not have the largest brains on the planet, either in absolute size or in proportion to body size. Whales, not people, have the biggest brains of any animal on earth.

Just how smart are whales? Why do they have such big brains? Bigger is not always better; maybe the inflated whale brain is not very sophisticated on a cellular level. We’re closer to answering such questions now, for a couple of recent papers address them squarely. What they find is helping separate fact from fiction.

It turns out that while whales have bigger brains, humans have more neurons. Nevertheless, whales have more glial cells.

Glial cells were traditionally thought to do nothing more than support and insulate the neurons, but it’s becoming increasingly clear that they’re actually part of the brain’s processing system (although they’re exact role is far from clear).

So maybe there’s a lot more to the whale brain that it first appears.

Link to ‘Are Whales Smarter Than We Are?’.

The resistence of memory in hypnotic amnesia

Research just published in neuroscience journal Neuron has discovered some of the brain networks behind post-hypnotic amnesia. Importantly, the study might give us an insight into how memories are repressed from consciousness.

Psychogenic amnesia is a type of memory disorder where there is no brain damage to explain the memory loss. Unlike amnesia after brain injury, which usually causes an inability to form new memories, psychogenic amnesia typically results in the person being unable to remember past events.

Most memory research involves comparing how well people recognise or recall information that they’ve been shown earlier.

One of the difficulties in studying psychogenic amnesia is that you’re never sure whether the memories you’re asking about were taken in, but are inaccessible, or whether the person simply didn’t register the information in the first place.

Amnesia caused by hypnosis is remarkably similar to psychogenic amnesia in many ways, but has the advantage of being temporary and reversible.

This is important because it allows researchers to show people information, then induce hypnotic amnesia and check memory, and then reverse the effects and check memory again.

The final memory check shows that the person genuinely took the information in to start with, so you know that the amnesia was for memories that were definitely there already.

Post-hypnotic amnesia is where a suggestion is given during hypnosis that the person won’t remember a specific event after the hypnosis is over. Because hypnotisability varies between individuals, it doesn’t work for everybody, but for those who experience this type of temporary memory loss, the effect can be quite dramatic.

In an initial session, researchers showed high and low hypnotisable participants a 45 minute film which they were told to remember.

A week later, they were put in an fMRI scanner, hypnotised and told to forget the film when the hypnosis was over. Crucially, they were told that their memories would return when given a specific command.

They were then scanned while being asked “yes/no” questions about both the film itself and other details about the initial session (such as whether the door to the testing room was open).

Unlike facts about the film, the participants were never told to forget these other details, allowing the researchers to test how specific the amnesia was.

The ‘hypnosis resistant’ low hypnotisable participants were equally good at recalling facts about the film and the testing session.

For high hypnotisable participants, although they were good at remembering session details, they were no better than chance at answering the questions about the film. In other words, they would have got the same number of questions right if they flipped a coin – suggesting their memory was quite impaired.

When given the command to remove the amnesia, the high hypnotisable participants could then recall the film as well as the others.

(Partly owing to the scepticism about hypnosis, the researchers also tested another group of people who were told just to pretend to be hypnotised. They performed quite differently – vastly exaggerating their memory difficulties – indicating that the high hypnotisable participants weren’t faking or ‘conforming’).

When trying to recall information when post-hypnotic amnesia was in effect, activity in the temporal lobes and occipital lobes was reduced, while activity in part of the frontal lobes increased.

The areas of the temporal and occipital lobes are known to be involved in dealing with factual and visual information, while the frontal lobes are known to be involved in coordinating other brain areas.

In this case, they seem to be inhibiting the function of other areas, perhaps preventing recall and explaining the amnesia.

Interestingly, when the amnesia was reversed, brain circuits involved in long-term memories became more active as the participants were able to answer questions.

This study might explain how psychogenic amnesia works. Perhaps this syndrome results from the same brain mechanism being ‘locked’ in place, persistently ‘repressing’ memories.

In fact, there’s a whole range of apparently neurological problems but where the person has no recognisable brain damage. These usually get diagnosed as conversion disorder and can involve everything from blindness to paralysis.

Two studies have just come out which point in the same direction as this hypnosis study.

In one, several patients with structurally normal brains were found to have under-activation in certain areas corresponding to their conversion disorder paralysis.

In another, when a patient with conversion disorder was asked to recall the traumatic event which triggered her paralysis, brain activation suddenly dropped in the brain areas that controlled movement in her immobile limbs.

What these studies are suggesting is that problems can arise in the operation of seemingly intact brains that can lead to what appear to be neurological problems.

An analogy might be that while the roads are intact, traffic jams can still bring a city to a standstill. The trick, of course, is to get the traffic flowing again.

The more we understand about how the flow gets disturbed, the more likely we are to help patients get things running smoothly again.

Link to abstract of post-hypnotic amnesia study.
Link to write-up of study from Science News.

Why we love (and flirt)

Time magazine has a couple of articles on the psychology of love, sex and attraction. The first looks at the science of love, from thoughts to hormones, and the second at what we know about flirting.

The love article is a more in-depth look at the topic of the two articles, and touches on studies that have taken place everywhere from the delivery room to the brain scanner.

It’s a little basic in places (e.g. it uses the dopamine = reward line a little uncritically), but is otherwise an interesting read.

A deep voice, also testosterone driven, can have similarly seductive power. Psychology professor David Feinberg of McMaster University in Ontario studied [pdf] Tanzania’s Hadza tribesmen, one of the world’s last hunter-gatherer communities, and found that the richer and lower a man’s voice, the more children he had. Researchers at the University of Albany recently conducted related research [pdf] in which they had a sample group of 149 volunteers listen to recordings of men’s and women’s voices and then rate the way they sound on a scale from “very unattractive” to “very attractive.” On the whole, the people whose voices scored high on attractiveness also had physical features considered sexually appealing, such as broad shoulders in men and a low waist-to-hip ratio in women.

This suggests either that an alluring voice is part of a suite of sexual qualities that come bundled together or that simply knowing you look appealing encourages you to develop a voice to match. Causation and mere correlation often get muddied in studies like this, but either way, a sexy voice at least appears to sell the goods. “It might convey subtle information about body configuration and sexual behavior,” says psychologist Gordon Gallup, who co-authored the study.

The flirting article is, rather predictably, a bit more light-hearted and largely talks about theories rather than evidence.

You’re probably better off trying your luck with the guide to flirting from the Social Issues Research Centre that looks at what sociology can tell us about being playfully alluring.

Link to Time article ‘Why we love’.
Link to Time article ‘Why we flirt’.
Link to Social Issues Research Centre guide to flirting.

Sensory Processing and Neurotopographics

While we’re on the subject of art and neuroscience I recently discovered a couple of pieces that caught my interest.

The picture is a piece by Sandra Dawson called ‘Sensory Processing’ which has combined a cap used for EEG recordings of the brain with comforting objects and materials.

I recycled two EEG caps, cut up pyjama bottoms which were freeform crocheted with the leads and black yarn, with iPod headphones
symbolizing synaesthesia with output from the eye going to the ear.

It’s called “Sensory Processing” and is meant to evoke sensual comforts (music, flannel) that are perceived and processed by the brain; only with my hat, it’s abstracted and externalized into fashionable form so that viewers ponder connections.

It’s part of a show currently on at the Femina Potens gallery in San Francisco until January 28.

The other piece is one I saw at the weekend called Neurotopographics and is a collaboration between artist Antoni Malinowski, architect Bettina Vismann and neuroscientist Hugo Spiers.

It takes inspiration from the recent discovery of three types of neurons that seem specialised for spatial awareness and navigation.

Place cells provide a ‘you are here’ signal; grid cells signal information about distances travelled and head direction cells provide a sort of internal compass.

So far, these have only been discovered in rats, but Spiers and his collaborators have created a film of how they might operate in humans.

In fact, they’ve created three films which run simultaneously:

The resulting artwork – which will be on show at the Gimpel Fils Gallery from 18–21 January – follows the journey of a person through space, in this case the gallery itself. The actor is filmed from two camera viewpoints: a static wide angle position, which records movement and spatial position, similar to a surveillance camera; and from a dynamic point of view, filmed out of the perspective of the actor’s eyes, recording the subjective impressions of the space and his journey through it. The films will be simultaneously projected onto the gallery walls and combined with a two-dimensional animation displayed on the floor representing assumed brain cell activity patterns.

Rather annoying, the website only works properly in Explorer, but the film from the observational point of view and the firing of the cells can be experienced online.

Link to Femina Potens gallery.
Link to Neurotopographics website.

Not seeing the wood for the dendritic trees

The LA Times has an article by Jonah Lehrer arguing that we can’t solely understand the mind and brain by reductionism – the process of working out smaller and smaller components of what we’re trying to study.

He argues that an approach that uses only measurement will never capture the complexity of subjective experience and that cognitive science needs to rediscover the value of first-person experience if it is to truly capture human thought and behaviour.

Lehrer suggests that the arts might be a way of re-addressing the balance:

The question, of course, is how neuroscience can get beyond reductionism. Science rightfully adheres to a strict methodology, relying on experimental data and testability, but this method could benefit from an additional set of inputs. Artists, for instance, have studied the world of experience for centuries. They describe the mind from the inside, expressing our first-person perspective in prose, poetry and paint. Although a work of art obviously isn’t a substitute for a scientific experiment — Proust isn’t going to invent Prozac — the artist can help scientists better understand what, exactly, they are trying to reduce in the first place. Before you break something apart, it helps to know how it hangs together.

Virginia Woolf, for example, famously declared that the task of the novelist is to “examine for a moment an ordinary mind on an ordinary day … [tracing] the pattern, however disconnected and incoherent in appearance, which each sight or incident scores upon the consciousness.”

In other words, she wanted to describe the mind from the inside, to distill the details of our psychological experience into prose.

Woolf and her fellow ‘stream of consciousness’ writers, however, were latecomers to this particular challenge.

The phenomenologist philosophers, most notably Karl Jaspers and Edmund Husserl, were attempting to chart the subjective structure of the mind in the early 1900s.

While scientific psychology has been the dominant research paradigm for the past century, there has been a small but dedicated band of psychologists, psychiatrists and philosophers who have attempted to continue the project.

In particular, psychiatry and clinical psychology involve the application of science to help patients who report disturbances in their subjective mental states, so this area has always been particularly influential in these areas.

In fact, it’s seeing something of a resurgence, with special issues of scientific journals being published on the topic.

Of course, Lehrer’s main point, that we ignore subjective experience at our peril, is exactly the thinking that led to the eventual death of behaviourism in the first half of the 20th century.

That’s not to say that behaviourism was worthless. Far from it. Many of the theories are still as valid today, but as with reductionism, beware when any tool becomes an ideology.

Art is another way of approaching an understanding of first-person experience of course, which is why Lehrer is arguing its benefit to cognitive science.

As it goes, I’m working on something similar at the moment, as I’m going to be co-teaching a course on cinema and the phenomenology of psychosis with psychiatrist Andrea Raballo and psychologist Frank Laroi at the next European Congress of Psychiatry, so look out for some musings on the topic in the coming weeks and months.

Link to LA Times article ‘Misreading the mind’.
Link to previous Lehrer article on art and science.

Wired on suicides of AI leading lights

Wired magazine has a feature article on the life, work and tragic deaths of two of the leading lights of Artificial Intelligence: Chris McKinstry and Push Singh.

Singh was a young researcher at MIT’s AI lab while McKinstry was considered a maverick and most of his AI work was conducted independently.

Both had a significant impact on the field as personalities and took a similar line in trying to make AI more focused on dealing with ‘common sense’ knowledge, rather than applying neural networks to complex pattern-recognition and transformation tasks as was more common at the time.

Interestingly, it seems from the Wired article that their ideas are experiencing something of a renaissance.

Tragically, both took their own lives. We covered the sad event of McKinstry’s death back in 2006, and the Wired article discusses the somewhat less clear circumstances surrounding the death of Singh.

Link to Wired article ‘Two AI Pioneers. Two Bizarre Suicides’.

Avalanches and Gnarls Barkley psychiatry mashup

Laptop Punk has created a mashup of two curiously complementary music videos: Gnarls Barkley’s Crazy and The Avalanches’ Frontier Psychiatrist.

The original version of Frontier Psychiatrist is a turntable satire on clich√©s about psychiatry and mental illness taken from films of the 1950s, that include mental illness being dangerous, psychiatrists having couches and patients being ‘crazy as a coconut’.

In contrast, Crazy gives us the modern voice of someone who’s lost their mind, but suggests that being betrayed in love is the greater madness.

When combined, they make an unlikely couple, but the musical mix works well and the contrast is wryly appropriate.

Link to Gnarls Barkley / Avalanches mashup.

Test your corpus callosum

I’ve just discovered a wonderfully simple finger touch procedure that can test the function of your corpus callosum, a key brain structure that connects the two cortical hemispheres.

It is called the ‘cross lateralization of fingertips test’ and was used in a 1991 study by Kazuo Satomi and colleagues.

It relies on the fact that different hemispheres are responsible for the movements and sensations from each hand.

In other words, each hand is connected to a different side of the brain, and, to allow you to co-ordinate both hands, the brain passes information between the two sides by using the corpus callosum.

The corpus callosum is the largest structure in the brain and works like a huge bundle of white matter ‘cables’, connecting different areas.

If this structure gets damaged, a patient might have trouble with coordinating their hands, preventing them from matching sensations on one hand with movement on the other, because the information doesn’t get to where it’s needed.

The test works like this: you need to ask someone to close their eyes and put their hands face up.

You then touch one of their fingertips with a pencil, and with the opposite hand the participant needs to touch the corresponding finger with thumb of the same hand.

For example, if you touched their right ring finger, they would need to touch their left ring finger with their left thumb, as shown in the diagram above.

You need to do this on both hands, with them always touching the corresponding finger on the opposite hand.

It’s important that the person keeps their eyes closed, because as soon as they look, they get information from the eyes, which goes to both hemispheres.

Patients who have damage to the corpus callosum (either because of acquired damage or because it just hasn’t developed) usually can’t do this test, because of the disruption in communication between the two hemispheres of the brain.

Of course, just to be sure its not a problem with movement or sensation in one hand only, the patient is also asked to do another quick test where they’re asked touch the exact finger you just touched.

For this part, the sensation and movement happen in the same hand, so information doesn’t need to cross the corpus callosum.

The test was shown to me by Dr Emma Barkus, who researches what neurological tests can tell us about psychosis and unusual experiences.

Link to Wikipedia page on the corpus callosum.
Link to abstract of Satomi and colleagues study (thanks Emma!).

The inner body

NPR’s radio show Talk of the Nation has a discussion with Sandra and Matthew Blakeslee, authors of a new book on the neuroscience of the body and movement.

If you’re interested in the ideas of embodied cognition that we covered the other day, the discussion touches on many of the major findings in cognitive science that are feeding into this important area.

The book, called The Body Has a Mind of Its Own, has a website which is somewhat sparse on readable excerpts but does have links to some more interviews about the topic.

The host of the NPR programme is a bit taken by the idea of ‘body maps’ (called sensory or somatotopic maps in the scientific literature), where areas of the body are literally mapped by the brain to represent sensation and movement, and the Blakeslees get asked lots of variations on the question ‘how do body maps explain x, y and z’.

Of course, somatotopic maps are only one part of a complex brain system that perceives the outside world and allows us to act within it, but I wonder whether this is a sign that ‘body maps’ might be the new ‘mirror neurons’ and become a popular explanation for everything from winning the World Cup to finding a partner.

Either way, Sandra and Matthew Blakeslee do a great job of explaining the science and trying to draw out some of the complexities.

Link to NPR discussion.
Link to The Body Has a Mind of Its Own website.