A fascinating report by Owen et al in Science documents one case in which a woman, completely unresponsive and diagnosed as being in a vegetative state, showed responses in her language and motor brain areas that were indistinguishable from normal. From a review by Miller: "Five months after an auto accident, she was unresponsive, unable to communicate, and met the clinical criteria for vegetative state. However, fMRI scans showed that language-processing regions of her brain became active when words were spoken to her but not when she was exposed to nonspeech sounds. Sentences containing ambiguous words such as "creek/creak" activated additional language regions, as they do in healthy people. These findings indicated that she retained some ability to process language... In another test, the researchers instructed the woman to picture herself playing tennis or walking through her house. In healthy people, imagining each activity activates a different set of brain areas involved in planning movements. The patient's fMRI scans showed an identical pattern--clear evidence, Owen and colleagues say, that she made a conscious decision to follow their instructions."
"Although some researchers aren't convinced Owen's team has cinched the case for consciousness in this woman, most agree that the fMRI scans reveal evidence of cognition that could not have been anticipated from standard MRI scans....Owen hopes to build on this work to develop a battery of fMRI tests for measuring cognitive functions in brain-damaged patients who are unable to communicate. He says this approach might someday be used to customize a patient's rehabilitation. For instance, if a patient's fMRI scans revealed an incapacitated visual system but a working auditory system, therapists could employ speech and sound."