Brain keeps its chat short and sweet as you go under

摘要

Anaesthetics usually knock you out like a light. Slowing the process down, though, has made clear exactly what happens while you are unconscious. Irene Tracey and her colleagues at the University of Oxford slowly injected 16 volunteers with the anaesthetic propofol. It took about 45 minutes for each one to become fully anaesthetised. EEG recordings revealed that before the volunteers became completely unresponsive to external stimuli they progressed through a sleep-like state characterised by slow-wave oscillations, in which neurons cycle between activity and inactivity. As the dose of anaesthetic built up, more neurons fell into this pattern, until a plateau was reached where no more neurons were recruited.