Brain Functional Connectivity in Wakefulness Predicts Susceptibility to Anaesthesia

There are considerable individual differences in susceptibility to anaesthesia, which will hamper development of reliable biomarkers to track the loss of reportable consciousness during anaesthesia. In the present study, we address this challenge by using functional Magnetic Resonance Imaging (fMRI) to quantify the effect of Propofol-induced changes in brain networks. fMRI data was collected while listening to an engaging narrative and during resting condition. Brain network specialisation, a measure for effective brain network function, was derived before and after mild sedation together with responsiveness to auditory target detection task. Reaction time (RT) was recorded. We found decreased brain system segregation, especially in association system, after mild sedation and such anaesthesia effect only presented during listening to the engaging narrative not under resting state. Particularly, functional connectivity between default mode network and salience network is significantly increased after mild sedation and participants showing lower connectivity at baseline were more likely to become unresponsive after mild sedation, despite similar RT during wakeful state. Our findings revealed the neural correlates under individual differences in susceptibility to Propofol and have the potential to inform improved brain state monitoring under anaesthesia, in future studies.