Functional Neuroimaging Approaches to the Changing Borders of Consciousness

Abstract

The bedside diagnosis of vegetative and minimally conscious patients is extremely challenging, and prediction of individual long-term outcome remains difficult. State-of the art neuroimaging methods could help disentangle complex cases and offer new prognostic criteria. These methods can be divided into to three categories: First, new anatomical MRI neuroimaging methods, like diffusion tensor imaging (DTI) or spectroscopy, and passive functional imaging methods (looking at the brain’s activation induced by external stimuli), could provide new diagnostic and prognostic markers. Second, neuroimaging methods based on active collaboration from the patient could help to detect clinically unnoticed signs of consciousness. Third, developments in brain-computer interfaces based on EEG, functional MRI, or EMG offer communication possibilities in brain-damaged patients who can neither verbally nor nonverbally express their thoughts or wishes. These new approaches raise important issues not only from a clinical and ethical perspective (i.e., patients’ diagnosis, prognosis and management) but also from a neuroscientific standpoint, as they enrich our current understanding of the emergence and function of the conscious human mind.