Face validity of whole-brain effective connectivity
To assess the face validity of EC measures, we compared thalamic connections and found that the effects (sign and significance) were consistent across FC and EC, although a recent study argued that this does not necessarily need to be the case [Comparing all connections, we found that FC and EC measures were broadly in agreement with one another as both indicated generally stronger connectivity under LSD, with some notably weaker connectivity between bilateral occipital areas, though this effect was more pronounced in the EC measure. Feature importance also suggested that the EC classification relied more heavily on the bilateral occipital connections than the FC classification, wherein connections involving more varied areas were represented among the highlighted ‘important` features (Figure 