Telephone: +353 (0)87 688 5642 24 Email: nacil@tcd.ie 25 26 to slow responders. Consistent with this finding, fast responders had significantly higher grey 48 matter volume in the frontal cortex aspect of the ECN. For the first time, these results show 49 that responsiveness variability during propofol anaesthesia relates to inherent differences in 50 brain function and structure within the executive control network, which can be predicted 51 prior to sedation. These results shed light on the brain bases of responsiveness differences 52and highlight novel markers that may help to improve the accuracy of awareness monitoring 53 during clinical anaesthesia. 54 al., 2020). Therefore, three brain networks with frontal and parietal lobe distribution, the 87 dorsal attention network (DAN), executive control network (ECN), and default mode 88 network (DMN) are primary candidate sources of individual variability under propofol 89 sedation. 90The DAN and ECN, distributed laterally across frontal and parietal lobes, are key to 91 orchestrating stimulus-driven and goal-directed cognition. Their roles include, orienting and 92 modulating attention to the saliency of incoming stimuli, monitoring and analysing 93 information from the environment and integrating it with internally generated goals, as well 94 as planning and adapting new behavioural schemas to take account of this information 95 (Duncan