Month: February 2007

Insula reality

As a perfect follow-up to recent news that damage to an area of the brain called the insula makes it easier to kick an addiction, The New York Times has an article looking more generally at the function of this fascinating neural structure.

The article is by science writer Sandra Blakeslee who has a history of teaming up with cognitive scientists to make their work accessible to a wider audience.

Two of her most notable books have included the strikingly original On Intelligence with Jeff Hawkins, and Phantoms in the Brain with V.S. Ramachandran.

[There’s a wonderful typo on Blakeslee’s site where she’s listed him as ‘VR Ramachandran’, which makes me think that in the future, everyone will have own virtual Ramanchandran’s to pose neuroscience questions to]

The NYT article looks at what is known about the insula, and why it seems to have been relatively neglected by cognitive neuroscientists until recently.

According to neuroscientists who study it, the insula is a long-neglected brain region that has emerged as crucial to understanding what it feels like to be human.

They say it is the wellspring of social emotions, things like lust and disgust, pride and humiliation, guilt and atonement. It helps give rise to moral intuition, empathy and the capacity to respond emotionally to music.

Its anatomy and evolution shed light on the profound differences between humans and other animals.

The insula also reads body states like hunger and craving and helps push people into reaching for the next sandwich, cigarette or line of cocaine. So insula research offers new ways to think about treating drug addiction, alcoholism, anxiety and eating disorders.

Of course, so much about the brain remains to be discovered that the insula’s role may be a minor character in the play of the human mind. It is just now coming on stage.

Link to NYT article ‘A Small Part of the Brain, and Its Profound Effects’.

From waves to the brain

Retrospectacle has a great beginner’s guide to hearing for anyone interested in how sound waves get converted into neural impulses for the brain.

The article describes the wonderful mechanics of the ear. It’s quite striking how much the physical make-up of the ear filters and ‘processes’ the sound waves before they even reach the sensory cells that connect with the nervous system.

All the hair cells sit on top of a firm but flexible membrane called the basilar membrane. As the stapes bangs against the oval window, a wave is transmitted through the basilar membrane. The distance this wave travels (and subsequently, the hair cells that are stimulated) are dictated by the frequency of the sound wave. The basilar membrane becomes stiffer at the top of the cochlea, which allows different parts of the cochlea to correspond to specific frequencies. High frequency sound-specifity corresponds to the base of the cochlea while the top (or “apex”) of the cochlea transduces low frequency sounds. The area on the cochlea where the most hair cells are stimulated during a given sound wave is considered the resonance point, and loudness can be perceived by the number and duration of hair cell stimulation at that point.

The article is both informative and wonderfully illustrated for those wanting to get a grip on one of our most interesting senses.

Link to Retrospectacle on ‘Basic Concepts: Hearing’.

Healthy relationships and the sound of success

PsyBlog has just started a series of articles investigating the psychology of relationships by examining recent research looking at how relationships may do our health as much good as a balanced diet and regular exercise.

Another article discusses why music is so commonly talked about when we’re getting to know someone. Partly, it seems, because we tend to see music choice as indicating something about personality.

Research has suggested that this might have some basis to it, as music choice seems to reliably indicate aspects of personality and reveals information not necessarily available through other sources.

Future articles in the series will explore other interesting aspects of relationships studied by psychologists.

Link to article ‘Why Health Benefits of Good Relationships Rival Exercise and Nutrition’.
Link to ‘Personality Secrets in Your Mp3 Player’.

Little memory men and spirit voices

A curious footnote on p183 from Mary Roach’s wonderful book on the natural history of the dead body Stiff: The Curious Lives of the Human Cadaver (ISBN 0141007451):

People have trouble believing Thomas Edison to be a loopy individual. I offer as evidence the following passage on human memory, taken from his diaries: “We do not remember. A certain group of our little people do this for us. They live in the part of the brain which has become known as the ‘fold of Broca‘… There may be twelve of fifteen shifts that change about and are on duty at different times like men in a factory…. Therefore it seems likely that remembering a thing is all a matter of getting in touch with the shift that was on duty when the recording was done.”

As well as his idiosyncratic views on memory, Eddison also thought that departed spirits might communicate through electrical equipment. In his writing, he refers to a device he had specifically designed for communicating with the dead.

Later, Dr. Konstantin Raudive, a Latvian psychologist and student of Carl Jung, continued Eddison’s work by looking for the apparent voices of spirits that appeared on audio recordings (known as EVP).

Critics suggest that the apparent voices are nothing but our brains trying to making sense out of essentially random data – something known as apophenia.

Raudive is pictured on the right with one of his special devices.

An unusual chapter in the history of psychology.

Link to Fortean Times article on the history of EVP.

London cabbie navigates with hippocampus damage

The hippocampus is thought to be essential for navigation. Surprisingly, a paper published last year reported that a London Taxi driver, who suffered hippocampus damage on both sides of the brain, could successfully navigate around much of London.

London black cab drivers must pass ‘The Knowledge‘ to get a license.

It involves memorising London streets and being able to work out, from memory, the best route between any two places in the city.

In 2003, neuroscientist Dr Eleanor Maguire and her team won the Ig Nobel Prize (a humorous award for discoveries “that cannot, or should not, be reproduced”) for a study that found that the hippocampi of London Taxi drivers were larger than average, possibly because the drivers are constantly exercising their spatial memory.

Despite winning the Ig Nobel, this paper has been very important in understanding both spatial memory and how the brain grows during adult life.

The same team of researchers published a paper last year, looking at the navigation skills of a London taxi driver who suffered selective damage to both his hippocampi after a brain infection.

If the hippocampi were essential for navigation, it would be thought that such a person would have lost ‘The Knowledge’ or would be unable to use it in practice.

They tested the driver in a complete computer simulation of London (pictured left) and discovered, to their surprise, that he was surprisingly good at orienting himself in the city and navigating the main roads.

He often became lost, however, when he moved away from the main roads and had to rely on smaller roads for navigation.

This suggests that the hippocampus is necessary for the fine-grained knowledge of locations rather than navigation in total.

The researchers suggest that as roads become more familiar, they may become more like ‘semantic knowledge’ (facts like ‘Paris is the capital of France’) that you can remember without bringing to mind the context in which you learnt it, or last encountered it.

They note that the main roads may have become more familiar over time and so have acquired a more semantic-like status.

As this occurs, the information would become independent of the hippocampus, allowing the brain-injured taxi driver to keep some of his hard-won Knowledge.

Link to abstract of study on PubMed.

Prescribing ecstasy

Slate has an article on the use of MDMA (‘Ecstasy’) in the treatment of people with post-traumatic stress disorder or PTSD.

Limited licenses have been granted to research the use of MDMA to assist in psychotherapy, particularly for trials in people with trauma-related stress.

It will shortly be trialled to see if it can help relieve anxiety and pain in terminal cancer patients.

The Slate article looks at these recent developments, and discusses how they might be practically applied in clinical treatment plans considering some of unwanted effects that might occur.

Link to article ‘What a Long Strange Trip It’s Been’ (via Dev Intel).

The romantic literature of recovered memories

The New York Times discusses a recent challenge laid down by psychologists skeptical of claims of recovered memories: find a single account of repressed memory, fictional or not, before the year 1800.

The researchers claim that the earliest account is from the 1782 novel Dangerous Liaisons and have published their findings in the journal Psychological Medicine.

They suggest that the idea of a recovered memory is a cultural invention and people are likely to arrive at the clinic with trauma and memory problems already shaped by these ideas.

The challenge has revisited a long-standing and heated debate over the reality of recovered memories that first exploded in the 1980s.

At the centre of the storm were people who claimed to have recovered memories of childhood abuse, often after hours of unusual or maverick forms of therapy.

The sheer numbers of people claiming to have uncovered repressed memories of abuse led some psychologists to question the reality of many of these memories and doubt that a healthy person could effectively repress whole episodes of their life, only to have them return later.

Researchers began to investigate the psychology of recovered memories in the lab and found evidence that false childhood memories could easily be induced in healthy participants [pdf] but also that memories could be deliberately ‘forgotten’ to some extent [pdf].

In response to the literary challenge, other researchers have offered earlier examples, but the challengers have dismissed them as not fitting their criteria adequately.

How much culture affects the expression of both normal and disordered thinking is currently a poorly-understood area and will probably become a major force in psychology over the coming decades.

Link to NYT article ‘A Study of Memory Looks at Fact and Fiction’.
Link to PubMed entry for the Psychological Medicine paper.

Furious Seasons

Furious Seasons is a blog about psychiatry and mental health by a ‘long-time psych patient’. What makes this blog different is that the author is also an award-winning investigative journalist.

The blog reports on the good and bad in mental health, keeping tabs on both shady commercial interests and significant treatment advances.

It also looks at personal issues in dealing with mental illness and examines how the mainstream media makes sense of this contentious issue.

Link to Furious Seasons.

Overlooking infinity

“From my fourth-floor room overlooking infinity, in the viable intimacy of the falling evening, at the window before the emerging stars, my dreams – in rhythmic accord with the visible distance – are of journeys to unknown, imagined or simply impossible countries.”

Text 421 (‘Journey in the Mind’) from The Book of Disquiet (ISBN 0141183047) by Portuguese poet Fernando Pessoa.

All shopped out?

Science and Consciousness Review has a short but interesting piece by neuroscientist Bernard Baars on recent findings on the neuroscience of buying.

An fMRI brain-scanning study published earlier this year in science journal Neuron [pdf] reported that when someone was making a decision to buy something or not, the brain activity could be reliably tracked through the buying process.

Crucially, when the product was first presented, activity in the nucleus accumbens was strongest. This area is often typecast as the ‘pleasure centre’ of the brain.

Later, other areas in the brain seemed to inhibit the nucleus accumbens when other factors, such as price, were considered to override the desire to buy.

However, Baars notes that there are other interpretations of the data as the method for brain scanning, fMRI, only gives an indirect measure of brain activity.

For example, the brain activity could be equally related to attention or anxiety.

This is a typical problem with new findings in cognitive neuroscience. With potentially important findings, much later work will try and determine to what extent these other factors are involved.

Link to SciCon Review article ‘Shopping Centers in the Brain’.
Link to SciAm write-up of original study.
pdf of full-text of scientific paper.

2007-02-02 Spike activity

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

Make Beautiful Brain Music. Wired covers the creation of brainwave-based music. Even better it’s touring!

MSNBC visits the Newberg lab to discover how researchers are studying the neuroscience of spiritual experience.

The New York Times discusses the psychology of email spam.

Furious Seasons keeps tabs on the ongoing court case concerning the antipsychotic drug olanzapine.

What’s going on in George Bush’s mind? The New York Magazine speculates.

Developing Intelligence examines research on change blindness and attention.

Explaining piano skills: Deric Bownds discusses a study that suggests that the brain makes specific connections between action and sound areas.

The promise of heroin

Andrew Tyler describes the attraction of heroin, from p275 of Street Drugs (ISBN 0340609753).

The book is considered one of the best guides to the culture, markets and effects of society’s common illicit drugs and is widely read by professionals who deal with drug users.

So what is this strange romance with heroin? Why, when people discuss it, do they leave their shoes and talk in symbols and metaphor? The heroin experience, for those who don’t let the drug run away with them, is warm, woozy, and carefree. Nothing matters any more in their beautiful bubble. For everyday users who have lost control, the experience is ultimately a mediocre one. The drug does not open doors to other worlds (like LSD) but closes them. It stupefies and kills feeling.

Perhaps the key to understanding heroin is to recognise that, for most of these compulsive users, it serves as an antidote to a wretched existence – lives that might be full of pain, might be too complicated to manage, or – conversely – empty of any meaning whatsoever. Heroin promises neutrality. It promises nothing.

If you’re not familiar with the pharmacology of heroin, you may be interested to know that heroin itself is largely inactive as a drug.

Heroin is a type of prodrug – meaning that it only becomes active after it is absorbed and metabolised.

The heroin molecule gets converted into morphine, which binds to the opioid receptors in the brain to have the desired effect.

Ironically, in it’s early days, heroin was marketed as a non-addictive treatment for morphine addiction.

Link to Wikipedia page on heroin.

Brains in silicon

The cover story of today’s New Scientist discusses the work of Dr Kwabena Boahen who is creating microchips with neural networks designed into the hardware.

Building functions into microchips mean they run fast and efficiently, despite the fact it reduces the flexibility of what the hardware can do.

Artificial neural networks can require a lot of computer processing power because every simulated neuron in the network is essentially a mathematical procedure that needs running every time the network is updated.

With a frequently updated network of thousands and thousands of simulated neurons, the required computing power quickly adds up.

What Boahen and others are doing is building microchips that have functions to simulate neurons built into the hardware to make this possible on only a few chips.

Crucially, some of the simulation is done by analogue, rather than digital, computation.

Digital processors use transistors in their on/off switching phase. Mead realised that by using transistors in their analogue amplifier phase instead, he could build circuits that accurately mimicked the electrical behaviour of real neurons. Using transistors in this way also meant Mead could dispense with the central clock altogether, dramatically cutting the power demand. As long as the input signals arrived within a few milliseconds of each other, the circuit of transistors imitating a given neuron would sum the input values, and if that tipped over a certain threshold, would produce an output spike. “It’s totally foreign to the way we’ve built computers for the last 40 years,” says Boahen.

Neural networks can try and simulate real neurons as closely as possible, or be quite abstract or general impressions of them.

The New Scientist article notes that these hardware-based systems are also intended to mirror the brain’s biology quite closely.

Closely enough, that the systems are being used for designing replacement retinas to augment parts of the damaged visual system in humans.

Unfortunately, the article isn’t freely available online, but you should be able to pick up a copy in your local library or newsagent.

However, the Brains in Silicon lab at Stanford University has a comprehensive website with a host of information if you want to find out more.

Link to article preview.
Link to Brains in Silicon lab.