Skin conductance responses
To remove artefacts related to US presentation, all data points in the period from 0.2 s before US onset to 1.6 s after US onset were treated as missing values in all SCR analyses. Data were then visually inspected for remaining artefacts. One participant (doxycycline group) was excluded from all SCR analyses because of inadequate quality of the SCR signal but retained in all other analyses. SCR analysis was adapted from the procedure benchmarked in 