A default mode of brain function in altered states of consciousness.

The brain's default mode network, a set of regions active during rest and mind wandering, shows synchronized activity that is anticorrelated with networks handling external attention. In disorders of consciousness such as the vegetative state (unresponsive wakefulness syndrome) and minimally conscious state, the integrity of the default mode network correlates with the level of remaining consciousness. This finding suggests that functional brain imaging could serve as a diagnostic and prognostic tool alongside standard behavioral assessments. The network's disruption is also observed in sleep, anesthesia, and hypnosis.

Study at a glance

Abstract

Using modern brain imaging techniques, new discoveries are being made concerning the spontaneous activity of the brain when it is devoid of attention-demanding tasks. Spatially separated patches of neuronal assemblies have been found to show synchronized oscillatory activity behavior and are said to be functionally connected. One of the most robust of these is the default mode network, which is associated with intrinsic processes like mind wandering and self-projection. Furthermore, activity in this network is anticorrelated with activity in a network that is linked to attention to external stimuli. The integrity of both networks is disturbed in altered states of consciousness, like sleep, general anesthesia and hypnosis. In coma and related disorders of consciousness, encompassing the vegetative state (unresponsive wakefulness syndrome) and minimally conscious state, default mode network integrity correlates with the level of remaining consciousness, offering the possibility of using this information for diagnostic and prognostic purposes. Functional brain imaging is currently being validated as a valuable addition to the standardized behavioral assessments that are already in use.