Uncoupling immobility and unconsciousness.

Anaesthetic endpoints such as immobility and unconsciousness are defined at the population level through metrics such as minimal alveolar concentration (MAC) and MAC-awake, yet how individuals behave at those concentrations remains poorly understood. In a recent study in the British Journal of Anaesthesia, Mandel and colleagues address this by characterising the behavioural dynamics of mice held at fixed concentrations of isoflurane corresponding to either population MAC or MAC-awake, and tracking whether they right themselves or respond to a paw pinch across repeated testing. Both endpoints flip states unpredictably yet resist switching and, interestingly, are wholly independent of one another.