ABSTRACT
Following coma, some patients will recover wakefulness without signs of consciousness (i.e., vegetative state) or may show nonreflexive movements but with no ability for functional communication (i.e., minimally conscious state). Currently, there remains a high rate of misdiagnosis of the vegetative state. The increasing use of fMRI and EEG tools permits the clinical characterization of these patients to be improved. We first discuss "resting metabolism" and "passive activation" paradigms, used in neuroimaging and evoked potential studies, which merely identify neural activation reflecting "automatic" processing-that is, occurring without the patient's willful intervention. Secondly, we present an alternative approach consisting of instructing subjects to imagine well-defined sensory-motor or cognitive-mental actions. This strategy reflects volitional neural activation and, hence, witnesses awareness. Finally, we present results on blood-oxgen-level-dependent "default mode network"/resting state studies that might be a promising tool in the diagnosis of these challenging patients.
ABSTRACT
Seeing a bright light at the end of a tunnel or having a sense of being out of the physical body are phenomena that some patients report after having been close to death. Some spiritual and psychological theories have been developed in order to explain these near-death-experiences. Clinical studies have aimed to determine their frequency and to assess their precipitating factors. Recent neuroimaging studies, however, have shown the involvement of the temporo-parietal cortex in the generation of out-of-body experiences and are offering a physiological, neurological account for the phenomenon, rebuffing dualistic, non-physical explanations.