Imaging the rise and fall of consciousness in damaged and healthy brains
2010 - onbekend
To what extent are comatose or vegetative state patients conscious of their environment? Do they still have any feelings, thoughts or memories? Currently, this is mainly gauged using detailed behavioral tests in which patients are asked to respond to visual, auditory or tactile stimuli. But what if the ability to communicate is lost, but consciousness itself remained? Ideally, we don?t want to ask about conscious experience, but look for it in the brain directly. Unfortunately, we don?t know yet what to look for. Recently, brain-imaging studies showed ?islands of activity? when patients were presented with auditory or tactile stimuli. However, this doesn?t say much, because the mere activation of specific parts of the brain doesn?t necessarily generate consciousness. We need a proven neural signature of consciousness. Recent evidence suggests that dynamic recurrent interactions between brain regions might fit that bill. This neural mechanism enables the exchange of information throughout the brain and its purposeful maintenance over time. With brain-imaging tools, we will test whether these two characteristics are true hallmarks of the content of consciousness in healthy volunteers. Next, we will use these neural measures to infer the level of ?impaired? consciousness in non-communicative brain-damaged patients.