Abstract

It is debatable as to whether the spontaneous blood-oxygen-level dependent fluctuations that are observed in the resting brain in turn reflect consciously directed mental activity or, alternatively, constitute an intrinsic property of functional brain organisation persisting in the absence of consciousness. This report shows for the first time, in three patients, that the persistent vegetative state (PVS) is marked by a dysfunctional default mode network, with decreased connectivity in several brain regions, including the dorsolateral prefrontal cortex and anterior cingulated cortex, especially in the right hemisphere. This finding supports the view that the resting state is involved in self-consciousness, and that the right-hemisphere default state may play a major role in conscious processes. It is speculated that the default state may act as a surrogate marker of PVS with awareness contents and, therefore, could replace a more complex activation paradigm.