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John-Dylan Haynes

Bernstein Center Berlin,
Charité Universitätsmedizin Berlin


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In search for consciousness

With imaging methods like nuclear magnetic resonance (NMR) tomography, scientists can observe which areas of the brain are active when processing visual stimuli, planning movements or even experiencing fear, joy or rage. Presumably, however, there is much more information in the NMR-images than what up until now has been elicited. It is this additional information that John-Dylan Haynes, professor for ‘Theory and Analysis of Large-Scale Brain Signals’ at the Bernstein Center for Computational Neuroscience Berlin since November 2006, intends to retrieve with improved data analysis methods. ‘We are still far from building a machine that can read your mind’, says Haynes. However, he is convinced that in the next few years, scientists will make substantial progress in decoding mental states such as consciousness or intention.

Today, NMR tomography is used to analyze changes in the brain that are related to certain tasks, like processing a visual stimulus or planning and executing a motor activity. If the activity in a certain area of the brain strongly increases, scientists can conclude that this brain area is involved in the respective task. Conventional methods consider the changes in different areas of the brain independently. In practice, however, it is often not possible to attribute complex reactions of the brain to clearly defined areas. The isolated analysis of single sample points therefore misses a lot of information. Haynes seeks to overcome this problem by using ‘multivariate pattern recognition’–an advanced method to which he strongly contributed. ‘We do not go through the data point by point. Rather, we look for spatially distributed activation patterns that are characteristic for certain mental conditions,‘ states Haynes as he describes his concept. ‘If you compare, for example, a photo of a man and a woman point by point, you will find that individual pixels are brighter in one or the other picture. But only the conjunction of all points carries information about whether it is a picture a man or a woman. Once we have captured the activation patterns in the brain, we will be able to derive the behavior and experience of a person, only by looking at their brain activity’.

What happens in the brain when we consciously perceive a visual stimulus? This question is one of Haynes’ main research focuses. ‘Current research tells us that the brain detects a lot of details that do not enter consciousness,‘ Haynes explains. By using multivariate pattern recognition, Haynes could show, for example, that the brain processes visual information to a certain degree, even if we see it only for a fraction of a second and therefore do not notice it consciously. What does the brain do with this information? ‘The idea that human behavior can be manipulated by such subliminal stimuli has been picked up by the popular scientific press for decades–simply because it fascinates people,‘ says Haynes. In this way, rumors developed that commercial strategists or political campaigns manipulated people through subliminal messages. If anything, they were certainly not very successful in this attempt. According to Haynes, ‘such information does not have any effect on complex human behaviors’.

Visual information is processed in the brain in different stages. Only a fraction of the information reaching our retina enters consciousness. Does this imply that it has to have a certain structure and that it needs to be processed in a certain way? How does the brain encode consciousness? Haynes sought to answer these questions by an intricately designed experiment, in which subjects were presented with a red stimulus in one eye, and a blue stimulus in the other. Under these conditions, subjects do not perceive a mixed color, but rather, their conscious experience is dominated by the information in either eye in turn – they alternately see red or blue. Since the visual stimulus in this experimental setup did not change, Haynes could be sure that any change in brain activity exclusively reflected a change in consciousness. The experiment showed that only higher processing levels in the brain show an activity structure reflecting conscious perception.

‘Brain areas, in which conscious perception takes place, are strongly interconnected with other areas of the brain’ explains Haynes. ‘The perception of color, brightness and movement perception must be integrated so that a visual perception can enter our consciousness’. The recognition or interpretation of what we see is another independent step. ‘If we look at a painting by Wassily Kandinsky, we can experience that indeed we are able to perceive images consciously without being able to interpret them’, says Haynes.

The question about the neural code of consciousness is not the only research interest of Haynes. The advancement of methods for the analysis of brain activity also allows investigating of other mental states, such as intentions or attention. Can one, for example, predict which actions a person is planning from the neural activity–even before he or she is aware of it? How do we control our attention? How can the thoughts of a person be read from his or her brain activity? Answering such questions is not only of academic interest, but suggests various applications in man-machine interactions, such as the control of artificial prostheses or computers by means of patients’ brain activities.