Month: November 2008

BBC Radio 4’s excellent discussion programme In Our Time just had an interesting edition on neuroscience – what it does, how it does it, and what it’s telling us about the function of the mind and brain.

It’s generally a very interesting discussion, although does get a bit confused towards the end during a discussion of conscious – largely due to a misunderstanding of a famous study.

The discussion touches on neuroscientist Adrian Owen’s study where they wanted to find out whether a patient in a persistent vegetative state (PVS) was conscious by asking them to imagine things and then using fMRI to see if the relevant parts of the brain were active – in other words, if the person was able to consciously hear, understand and carry out the request.

Famously, the patient could – demonstrating that it is possible to be diagnosed with PVS and still be conscious.

However, the guests on the programme discuss the study as if the patient was unconscious and was in a coma, and suggest that this shows the brain can do remarkable things when someone is unconscious which is exactly what it didn’t show.

Otherwise, a fascinating discussion as we’d expect from In Our Time.

Link to programme webpage and audio.

Neurophilosophy has recently published two excellent articles that discuss the recent discovery of very selective psychological problems: one person can’t recognise people by their voice, the other can’t navigate through streets.

In themselves, these sorts of disorders are not that surprising, but they help us understand how the brain develops.

Actually, scratch that last sentence. If you’re familiar with the brain injury literature, these sorts of disorders are not that surprising, but if you’re not, they’re completely mind blowing.

Take prosopagnosia for example. Sometimes rather inaccurately called ‘face blindness’ (people see faces, they just don’t seem distinctive) it was first identified in a patient with a bullet wound to the head who lost the ability to recognise faces but could still recognise other objects.

If you think about it, this is incredible. When we look out onto the world, faces don’t seem different from the rest of the things we look at, but damage to a specific area of the brain (most commonly the right fusiform gyrus) can selectively damage our ability to see faces, suggesting that there are brain functions specialised for this task. How specialised, whether only for faces, is a matter of ongoing debate, but the fact that they are specialised at all is incredible enough.

The explanation for these selective impairments goes something like this: our brain functions are shaped by a combination of the broad outline of genetics and the fine tuning of experience during growth. When we reach adulthood they are fairly fixed. Damaged can knock out these fairly fixed pathways leading to selective impairments.

What has become clear over the last decade is that some people can have selective impairments without suffering brain injury. They seem to have them from birth.

This is the case with the two people discussed by Neurophilosophy. An inability to recognise people by just their voice or an inability to navigate streets after brain damage is interesting but not earth shattering. These sorts of cases have been reported before.

But the fact that these are developmental disorders is an interesting and important twist, not least for what they suggest about how much certain functions might be ‘set’ in the brain early on, but also for what they suggest about the ‘life history’ or our cognitive skills.

The two case studies discussed by Neurophilosophy are both fascinating as life stories of people with atypical difficulties but also scientifically compelling because they help us understand complex dance of brain growth and development.

Link to piece on developmental topographagnosia.
Link to piece on developmental phonagnosia.

Scientific American Mind’s Mind Matters blog has a great interview with neuroanthropologist Daniel Lende who discusses why we need an understanding of both culture and neuroscience to get a fully integrated account of human thought and behaviour.

Lende discusses his work on integrating cultural factors and the neuroscience of the dopamine reward system in a study of addiction in Colombian teenagers.

A common approach in neuroscience is to take experiences labelled by everyday words and try and find what changes in the brain when someone says they are having the experience.

The problem is that the definitions of the labelling words may be indistinct (‘love’), incoherent (‘belief’) or understood differently in different cultures (‘anxiety’).

The approach Lende advocates is to take an anthropological approach to the problem. In other words, attempting to understand what a concept or label means in a particular culture so the neuroscience can be integrated in full knowledge of the diversity of the experience.

This predicament is where neuroanthropology can be so helpful. In order to draw connections between neuroscience and real world situations, I went out and talked to people to understand craving and addiction from their point of view. This type of real-world data can both challenge and inform ideas based on animal models and neuroimaging studies.

In translating the dopamine research, my work with adolescents proved crucial. They knew what they experienced far better than I did. Using systematic interviews across a range of involvement with drugs (hard-core users to having never tried drugs), I saw three areas of overlap between research on dopamine and compulsive involvement with addictive substances.

First was the emphasis that researchers placed on “wanting.” I was lucky in Colombia; addicted adolescents often described their experiences as “querer más y más,” to want more and more. Second, dopamine affects shifts in attention, which meant that some adolescents couldn’t focus on anything else when they knew an opportunity to consume was about to come along. Third, adolescents described a sense of being pushed toward something—an urge that rose up without conscious desire.

You may recognise Lende from the excellent Neuroanthropology blog and he also discusses some of the work of his co-bloggers in the interview, including some fascinating work looking on how people learn balance.

However, if you’re interested in more details about the study on Colombian teenagers, he’s recently posted some more information including links to the full text of the papers.

Link to SciAmMind Mind Matters interview.
Link to Neuroanthropology post on Colombia study.
Link to follow-up and more information.