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. 2013 Jan;154(1):124–134. doi: 10.1016/j.pain.2012.09.017

Fig. 4.

Fig. 4

The main effect of capsaicin, indicated in red, was to increase blood-oxygen-level-dependent (BOLD) activation in the anterior cingulate cortex (ACC) (Montreal Neurological Institute [MNI] peak coordinates −6, 20, 30; z score = 3.8) and thalami (left thalamus: MNI peak coordinates −12, −26, 16; z score = 3.2, right thalamus: MNI peak coordinates 10, −22, 14; z score = 3.6). The effect of interaction between delta-9-tetrahydrocannabinol (THC) and capsaicin, indicated in blue, was significant in the ACC only (MNI peak coordinates −8, 22, 28; z score = 4.6). The graphs clarify the effects of THC and placebo (PLC) on capsaicin-induced BOLD responses. Capsaicin-induced BOLD response was calculated as the difference (cap − con) in percentage BOLD signal change between capsaicin (cap) and control (con) sessions. Compared to PLC, THC decreased the BOLD response in the ACC related to hyperalgesia (top graph). In contrast, activation within thalami related to hyperalgesia did not differ significantly. Coloured bars denote range of z scores. Clear and black bars represented PLC and THC, respectively. Error bars represent SEM.