Consciousness unbound: toward a paradigm of general anesthesia.

THEORIES of general anesthetic mechanism have evolved from the unitary hypothesis of Claude Bernard in the nineteenth century to our current understanding of the multiple receptors and neural systems affected by anesthetic agents. As the scientific study of general anesthesia has progressed, it has become clear that early unifying theories of anesthetic mechanism, although elegant, do not account for the many specific actions of anesthetic agents. Studies of general anesthesia over the past years have ranged from the level of single-channel dynamics, to the analysis of neural systems controlling sleep, to neuroimaging. Although general anesthesia may be mediated by complex pharmacologic and neurologic mechanisms, we should not abandon the quest for a unitary hypothesis. Although such frameworks may be simplified, the lack of a guiding paradigm may ultimately impede the development of investigation. A paradigm of general anesthesia should be able to: