ReviewComa and consciousness: Paradigms (re)framed by neuroimaging

The past 15 years have provided an unprecedented collection of discoveries that bear upon our scientific understanding of recovery of consciousness in the human brain following severe brain damage. Highlighted among these discoveries are unique demonstrations that patients with little or no behavioral evidence of conscious awareness may retain critical cognitive capacities and the first scientific demonstrations that some patients, with severely injured brains and very longstanding conditions of limited behavioral responsiveness, may nonetheless harbor latent capacities for significant recovery. Included among such capacities are particularly human functions of language and higher-level cognition that either spontaneously or through direct interventions may reemerge even at long time intervals or remain unrecognized. Collectively, these observations have reframed scientific inquiry and further led to important new insights into mechanisms underlying consciousness in the human brain. These studies support a model of consciousness as the emergent property of the collective behavior of widespread frontoparietal network connectivity modulated by specific forebrain circuit mechanisms. We here review these advances in measurement and the scientific and broader implications of this rapidly progressing field of research.

► Neuroimaging shows cognition in some patients without motor responsiveness. ► This improves clinical and pain management of chronic disorders of consciousness. ► It permits selection for thalamic deep brain stimulation and plasticity enhancement. ► Awareness depends on frontoparietal and mesocircuit functional connectivity. ► Multi-center studies are offering evidence-based diagnostic and prognostic tests.