Monday, April 28, 2008

The objectivity of subjective experiences

Perhaps not enough has been made of the extent to which brain imaging techniques are beginning to enrich our understanding of the brain. Most people marvel – and with good reason – at the fact that these imaging techniques demonstrate with fair certainty that specific experiences – for example of colour or of visual motion – correlate with activity in a specific area of the brain. But imaging techniques have gone way beyond and have made what was thought to be outside the realm of objective observation the target of experimental studies, and with huge success. Fear, expectation of reward, the experience of love and of beauty – all of them thought until recently to be unverifiable, or not easily verifiable, subjective experiences - have been shown to have neural correlates specific to them. Hence, to ascertain that someone is in love, I need only show them the picture of their [suspected] lover and note whether there is any activity in the brain areas that have been shown to correlate with feelings of love. In time, no doubt lawyers will be using such evidence in court proceedings.

But there is another aspect to these studies that has escaped comment although its impact may yet turn out to be as great as the demonstration that subjective feelings have distinct neural correlates. The experience of beauty provides a very good example.

In 2004, Hideaki Kawabata and I published a paper showing that the experience of beauty correlates with activity in the orbito-frontal cortex, a part of the brain that is linked to reward. In that study, we showed subjects many paintings – abstract, landscape, portraits, still lifes – and asked them to rate the paintings in terms of their beauty. Different subjects gave different ratings to the same paintings. Sometimes, a painting judged to be of high beauty by one subject was given a low rating by another. Yet whenever a subject a painting in the scanner that they rated as beautiful viewed, there was increased activity in the orbito-frontal cortex. Moreover – and this is the critical point – the increase in activity was directly related to the declared rating assigned to the painting. Hence the subjective experience could be localized and quantified.

Ours is not the only study to show that the activity in specific parts of the brain is often quantifiably related to the declared subjective experience. At least two dozen other studies have shown the same result for different subjective experiences. This, it seems to me, is a major achievement of brain imaging studies. It brings subjective experiences firmly into the realm of measurable science.

Wednesday, April 16, 2008

The changing brain studied through violence

I have recently read a paper that, I believe, has not received the attention it deserves, at least in the media. It is a study of the re-organiztion of the brain in response to violence. What it is that suddenly triggers a violent behaviour in some individuals is not known with any certainty, but it has long been suspected that exposure to violence leads to increased violence. We have, after all, been repeatedly told that watching violent movies results in individuals who are more readily capable of violence. But why and how?

A paper by Chris Kelly and his colleagues at Columbia Univeristy has far-reaching implications in this regard. They showed volunteer subjects clips of violent films and measured activity in different areas of the brain, using brain imaging techniques. Their results show, in brief, that repeated exposure to violence reduces the intensity of activity in a specific region of the brain known as the lateral orbito-frontal cortex progressively. The implication here is that the more violent movies are watched, the greater the reduction in orbito-frontal activity. This in itself may suggest an adaptation that makes individuals more immune to violence, adaptation being a very common occurrence in the brain. But the study goes further, to show that connections between brain areas must be in a dynamic state, and hence modifiable by experience – in this case the experience of violence – even in adult life. For the orbito-frontal cortex is connected with another brain area – the amygdala – which is known to be responsive to fearful and aggressive faces. This connection seems to be critical in the control of aggressive behaviour. The strength of connections between the two brain areas diminished progressively as violent movies were watched, and led to more aggressive tendencies. The study also strongly suggested that there developed a progressive diminished control over the initiation of violent aggressive behaviour. For there was a concomitant increase in activity within areas known to be critical in motor planning (for aggressive behaviour, among others). This suggests that the connections between the orbito-frontal cortex and yet other regions of the cortex are also in a dynamic state.

It is important to note that the study exposed subjects to violent films over relatively brief periods, each clip viewed lasting seconds rather than hours, as is common for violent movies. Hence, it does not take prolonged exposure to alter strength of connections in the brain, and in this instance, to loosen the inhibition that leads to violent aggressive behaviour.

There is a lesson in this for society, and that is why I am surprised that so little has been made of it by the media. We have discussed endlessly whether the extent of violence shown in Western movies is not damaging our already violent societies. And yet here is a study, which shows that even brief exposure can alter the balance of connections in the brain and tip them in a direction that is not socially advantageous. And there is, perhaps, a problem for legislators too. What if someone can come armed with evidence derived from brain scans to show that the crimes that he or she has committed is the result of altered brain states, induced by watching violent movies? It would be a manner of shifting responsibility. I do not know enough about law to discuss this point, but I should not be at all surprised if defence of this kind surfaces in future hearings of criminal violence cases.

But there is, above all, a great deal of interest in learning that such complex behaviour is held in check by a fine system of balance through the interactions between brain areas and that this balance is so vulnerable – even over very brief periods and even in adult life – to environmental influences. There is much in this work that is of interest for future studies in the neurobiology of aggressive behaviour and violence.

Tristan und Isolde at the Met…..

It has now been established that there is an area in the visual brain that is specialized for registering human bodies or, to put it differently, that is active when we perceive bodies. This should not come as a surprise. The brain has devoted special areas to many features that are important to us, and human bodies are very, very important. Bodies do, after all, give us a lot of information about the psychological state of a person at any given moment; we can communicate much through our body language. And the brain seems to have developed a marvellous system for recognizing at a glance, through the perceived body language, whether one a person is arrogant or diffident, proud or humble, and much else besides. Which brings me to the Metropolitan opera’s recent production of Tristan und Isolde.

To convey visually all that there is in Tristan requires an artistic and dramatic flair that is evident not only in the motion of the singers on stage but also in their inaction, the postures they adopt in the still moments. From this point of view, the Met’s recent and ill-fated production was a disappointment, or at least partially so. The staging was visually stunning in its simplicity and very effective in its use of colour. It descended once into kitsch, when Tritsan and Isolde, having swallowed the love potion and realised their profound love for one another, the lighting turned to red, eliciting laughter from the audience (something which I have not experienced before) and distracting attention from the accompanying music. Both lead singers fell ill and did not appear together except for the final performance. Illnesses prior to or during performances are bound, I imagine, to have a severe negative effect on such demanding singing and acting roles. In the performance that I attended on March 25th, Deborah Voigt had cancelled out owing to her illness and was replaced by Janice Beard. It must be a nightmare to be forced into such a role at relatively short notice and I don’t think that she managed to pull it off. Tristan is a dignified hero, burning with a love so intense that he knows, and is resigned to, the fact that he cannot achieve it on earth. The love potion that he drank in the first Act made him inherit “eternal torment”, he laments in the last act. Ben Heppner, recovering from an illness, was not physionomically up to the role of Tristan on that particular evening. His body language simply did not convey what I believe the music intends him to convey. There was however one glorious moment, and it occurred at the end of Act 2, when King Marke sings his sad and beautiful lament: “Mir dies? Dies, Tristan, mir?” What was deeply impressive in this particular performance, apart from the splendid singing of Matti Salminen as King Marke, was the highly effective way in which body language communicated the psychological state of the protagonists – both Tristan and Isolde. They managed to communicate, through the immobile postures they adopted, as effectively as the music that feeling of unrepentant guilt, forced on them by factors beyond the control of either. It made me wonder about the neural mechanisms that underlie our ability to perceive so much in body language, even when still. Is this result of activity in the cortical area in which activity correlates with the presence of bodies? If so, then this area must be doing a great deal more than just registering the presence of bodies? Or is the activity in that area relayed, or perhaps influenced, by some other cortical area? To have felt what I felt during those moments, I assume that there is some connection with the emotional brain. Interesting questions for future study. At any rate, this one moment was worth crossing the Atlantic to see. Incidentally, I tried to see the live broadcast in London, where it was relayed to many theatres. Guess what, they were all sold out! Now on to Barcelona, for Robert Carsen’s extraordinarily rich – I speak from a neuroesthetic point of view, of course – production of Tannh√§user, last seen at the Bastille in Paris and about which I will blog in the future.

….. and neuroscience at the Italian Academy at Columbia

What were neuroscientists doing giving talks about the brain and its operations at the Italian Academy (www.italianacademy.columbia.edu), an institution supposedly devoted to Italian studies? And why did they have a full house, with many coming from the humanities? Well, the Director of the Academy, David Freedberg, is a wise man. He was among the first to embrace the field of neuroesthetics and understands that the humanities have much to offer to future studies of the brain, and that neuroscience in turn can help illuminate interesting and important problems in the humanities. The example I give above from Tristan is one among many. And the full house at the meeting he organized is testament to the fact that there are many who share this interest. All honour to David, to Anna Ipata, and to the excellent speakers at the meeting.