| | By Nick Farrell in Rome @ Wednesday, March 18, 2009 7:56 AM
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| | Boffins fooling around with electrodes in the brains of epileptics think they have worked out how consciousness works. Rather than working from a single part of the brain, consciousness is a group effort from the whole organ.
 The next stage is to find an objective 'consciousness signature' that could be used to probe the process in animals and people with brain damage without inserting electrodes.
Doctors had thought that there would be a dedicated brain area, or 'seat of consciousness', was responsible for guiding our subjective view of the world. Mind you the Ancient Egyptians thought that consciousness was in the heart and the brain's only function was to create nose mucus.
The only way that doctors could find what the brain was doing was by implanting electrodes into the skull but since this was so invasive they could never get the permission from the authorities.
Then a smart person realised that people suffering from epilepsy also needed to have electrodes implanted so they could ask them nicely to do their consciousness tests.
Neuroscientist Raphaël Gaillard of INSERM in Gif sur Yvette, France, and colleagues probed consciousness in ten people who had intercranial electrodes implanted for treating drug-resistant epilepsy.
They monitored these signals and flashed words in front of the volunteers for just 29 milliseconds. The words were either threatening or emotionally neutral. The words were preceded and followed by visual 'masks', which block the words from being consciously processed, or the masks following the words weren't used, meaning the words could be consciously processed.
The volunteers had to press a button to indicate the nature of the word, allowing the researchers to confirm whether the volunteer was conscious of it or not. During the first 300 milliseconds of the experiment, brain activity in both the non-conscious and conscious tasks was very similar, indicating that the process of consciousness had not kicked in. But after that, individuals who were aware of the words had an increase in the voltage levels of the signals in their brains. Then the frequency and phase of neurons firing in different parts of the brain synchronised and these signals appeared to be triggering others.
Gaillard's team argues that it constitutes a consciousness signature. As much of this activity was spread across the brain, they say that consciousness has no single centre and consciousness is more a question of dynamics.
The report into the study can be found here. X
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