A Reduced Level of Consciousness Primarily Affects Non-conscious Processes Johan Eriksson , Fontan, A., Lindgren, L., Pedale, T., Bergstrom, F., Brorsson, C. (Umea University, Umea, Sweden) P1
Until now, investigations of consciousness have used two basic experimental paradigms: one evaluating differences related to the content of consciousness (i.e. what is it like to experience something) and the other evaluating differences related to the global state of consciousness (e.g. sedated vs. non-sedated). There is currently a debate regarding how to conceptualize the relation between these two aspects of consciousness. Therefore, in this fMRI study, both aspects of consciousness were manipulated for the first time within a single experimental setting, which enabled us to formally investigate the relation between these two fundamental aspects of consciousness. If the level of consciousness indeed does have a specific relation to the content of consciousness, the decrease of the wakefulness should primarily reduce brain activity during conscious perception whereas brain activity during unconscious perception should be spared. Contrarily, we found that unconscious processing was more affected by the Propofol sedation compared to conscious processing. This result has implications for how to view the concept of consciousness, how to consider effects of anesthesia, and how development of neural markers of consciousness (e.g., to identify non-responsive patients with a spared capacity for conscious awareness) should proceed.