When faces fade

Prosopagnosia is an inability to recognise faces. It most commonly occurs after brain injury, although this week’s New Scientist reports on a recently completed study on a type of inherited prosopagnosia, suggesting a genetic basis for face recognition.

The research was an international effort, led by husband and wife team, geneticists Thomas and Martina Grüter. Notably, Thomas has a particular interest in this area, as he has prosopagnosia himself.

Unfortunately, the New Scientist article is only available to subscribers The full article is now available online, and Mind Hacks has spoken to two members of the research team about this intriguing study: Thomas on his own experience of prosopagnosia and the genetics of face recognition, and neuropsychologist Hadyn Ellis on the implications for the developing field of ‘cognitive genetics’.

Thomas and Martina are part of a team of geneticists from the Institute of Human Genetics in M√ºnster, Germany. They became interested in how Thomas’ condition seemed to run in families and decided to study it in more detail.

They recruited neuropsychologists from Cardiff University, initiating an international effort to examine the genetic basis of face perception.

The main finding of the study was that prosopagnosia seemed to be inherited in an autosomal dominant fashion, meaning only a single gene from one parent is needed to cause the condition.

Could it really be the case that the development of face recognition relies on a single gene ? We tackled Thomas on this controversial interpretation, but first we wanted to know, what it is like having prosopagnosia?

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How did you first realise you were unable to recognise faces as well as other people?

When I didn’t recognize my teachers in the street. Some didn’t care, but others were not amused. Most of the time, I wasn’t even aware that I had overlooked them, if so, they didn’t say a word.

What is it like having prosopagnosia ? For example, do faces seem strange or distorted to you?

Faces look perfectly normal, they just fade in my memory very quickly. I can recognize emotions as well as other people, maybe better.

To most people, not being able to recognise faces would seem a great disability. Why do you think most people with hereditary prosopagnosia are not significantly impaired by their condition ?

They have had all of their life to cope with the problem. They have learned to recognize people by other features like gait [walking style] or voice. And, of course, like colorblind people, they cannot imagine how it feels to remember faces normally.

On the basis of this study, you have argued that a single gene may be heavily involved in developing face recognition skills. Early studies in cognitive genetics also made bold claims (a ‘gene for language‘ for example) only to soften the claims when these genes were found to have wider effects.

Do you think that this potential ‘face recognition gene’ is likely to be genuinely face specific ?

The so-called language gene FOX2P was found to control the expression of other genes, instead of influencing the brain development directly. Still, the studies gave us a valuable insight into the regulation mechanisms of the genetic code.

The genetic code is not like a “blue print” of the body, in reality, the relationship is much more complicated. If we find the gene responsible for prosopagnosia, it may well be a regulator gene like the language gene, but of course, it may also be a gene influencing the connectivity of brain areas directly.

What is an important next step for the research and how do you see it being useful for people who might be affected by hereditary prosopagnosia ?

For people with hereditary prosopagnosia, an early diagnosis can make their life a lot easier. Our next step will be the development of a standard diagnostic procedure for prosopagnosia. Other groups are now trying to pin down the anatomical and functional difference in the brains of prosopagnosics.

In May, 2005, we will open a prosopagnosia clinic at the Insitute of Human Genetics in Münster, where hereditary prosopagnosia can be diagnosed and we can advise parents about the probability of their children being affected. Of course, we will also tell the parents how they can recognise the disorder in their children and what they can do to help. It is also important to remind everyone that prosopagnosia is not a disease, it is a cognitive disability, nothing more.

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The bigger picture is that this study is part of an increasing focus on understanding how genetics influence the development of the mind and brain. Team member and neuropsychologist Hadyn Ellis is convinced this will be an important step in understanding brain development.

“Until recently, genetics and neuropsychology have been separate areas of research. We are now able both to accurately measure brain function and target precise areas of the human genome. With these developments in the human sciences, it has become possible to link these effects with increasing accuracy.

This might eventually allow us to answer some of the age old questions about the role of nature and nurture in human development”.

The paper will be published in a forthcoming issue of the journal Cortex.

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Hungry for more info on cognitive genetics? Check out this paper (PDF) from a recent issue of Trends in Cognitive Sciences.