independent studies have implicated the caudate in goal-directed action selection (Grahn et al., 2008), and the insula in error awareness (Klein et al., 2013) and decision-making (Uddin et al., 2017). Unexpected omissions in reward, which produce negative prediction errors, were associated with stronger responses in the caudate. Unexpected rewards, which produce positive prediction errors, were associated with stronger responses in the insula. Heightened prediction error responses normalised following weight restoration. However, stronger prediction error signalling in the caudate during the acute phase of AN was associated with worse treatment outcomes