Fig. 6.

(Top) Delta-9-tetrahydrocannabinol (THC) significantly reduced the right amygdala and primary sensorimotor functional connectivity (Fc) during capsaicin-induced ongoing pain (z > 2.0; cluster-based correction). z-Scores indicating the degree to which THC reduced Fc are scaled in blue. Montreal Neurological Institute (MNI) coordinates are indicated at the bottom right of each slice. (Bottom-left graph) The dissociate effect that THC has on the intensity (INT) and unpleasantness (UNPL) of capsaicin-induced pain in each individual (represented by connecting lines). Negative visual analogue scale (VAS) units on the Y-axis indicate an analgesic effect. The dissociative effect of THC on pain was calculated as the absolute difference of drug effects on the intensity and unpleasantness of ongoing pain, and is indicated in dashed red lines and bracket for an individual. (Bottom-right graph) THC-induced reduction of sensory-limbic Fc was positively correlated with the dissociative effect of the drug on ongoing pain. The interaction term for the drug effect on the sensory-limbic Fc associated with ongoing pain is drug [PLC-THC] × state [CAP-CON]. For each individual, parameter estimates for the interaction effect were calculated for the left-S1 region of interest, which consisted of an 8-mm-diameter sphere centred on the group peak interaction (state × drug) effect within the post-central gyrus (MNI coordinates −34, −36, 62). PLC, placebo; CAP, capsaicin-sensitised state; CON, control state.