Unresponsiveness ≠ Unconsciousness
Robert D. Sanders, Giulio Tononi, Steven Laureys, Jamie Sleigh, David S. Warner
Anesthesiology February 7, 2012 DOI: 10.1097/aln.0b013e318249d0a7 via OpenAlex
Summary
Consciousness—subjective experience—persists during sleep and anesthesia, as evidenced by dreaming. A defining feature of dreaming is disconnection from the environment. Anesthesia aims to prevent the experience of surgery (connected consciousness) by inducing either unconsciousness or disconnection. The isolated forearm technique reveals that consciousness, connectedness, and responsiveness can uncouple during anesthesia; under clinical conditions, a median 37% of patients demonstrate connected consciousness. Potential neurobiological constructs explain this: during light anesthesia, subcortical mechanisms for spontaneous behavioral responsiveness are disabled, but information integration within the corticothalamic network continues producing consciousness, while unperturbed norepinephrinergic signaling maintains connectedness. These concepts emphasize the need for anesthetic regimens and depth-of-anesthesia monitors targeting mechanisms of consciousness, connectedness, and responsiveness.
Study at a glance
| Characteristics | Review Peer reviewed |
|---|---|
| Keywords | Unconsciousness Disconnection Medicine Social connectedness Anesthetic |
| Citations | 478 |
| Key finding | During anesthesia, consciousness, connectedness, and responsiveness can uncouple, with a median 37% of patients showing connected consciousness under clinical conditions. |
Abstract
Consciousness is subjective experience. During both sleep and anesthesia, consciousness is common, evidenced by dreaming. A defining feature of dreaming is that, while conscious, we do not experience our environment; we are disconnected. Besides inducing behavioral unresponsiveness, a key goal of anesthesia is to prevent the experience of surgery (connected consciousness), by inducing either unconsciousness or disconnection of consciousness from the environment. Review of the isolated forearm technique demonstrates that consciousness, connectedness, and responsiveness uncouple during anesthesia; in clinical conditions, a median 37% of patients demonstrate connected consciousness. We describe potential neurobiological constructs that can explain this phenomenon: during light anesthesia the subcortical mechanisms subserving spontaneous behavioral responsiveness are disabled but information integration within the corticothalamic network continues to produce consciousness, and unperturbed norepinephrinergic signaling maintains connectedness. These concepts emphasize the need for developing anesthetic regimens and depth of anesthesia monitors that specifically target mechanisms of consciousness, connectedness, and responsiveness.