Highly read on www.jneurosci.org in April

'Waking up' from an unconscious state requires the activation of only primitive areas deep in the brain — not the higher cortical areas indicated in previous studies on anaesthetized people.

Harry Scheinin at the University of Turku in Finland and his colleagues used position emission tomography to image the brains of 20 volunteers recovering from anaesthesia. The participants had been given either propofol, a standard anaesthetic, or dexmedetomidine, an unusual sedative drug that allows the individual to be awoken temporarily with a shout or a prod. The two-drug study design allowed the researchers to differentiate between brain activities due to the drug and those specifically related to the conscious state.

They found that a core neural network involving just subcortical brain areas and a primitive part of the cortex was activated as subjects recovered sufficient consciousness to respond to verbal instructions.

J. Neurosci. 32, 4935–4943 (2012)