[Figure 3 here]
Figure 3. ERPs at electrode Pz. Shaded area represents P300 peak amplitudes for Happy (top), Angry (bottom left) and Neutral (bottom right) Faces with ERPs shown for PLC (blue), MA (red) and MDMA (green) sessions. Neither MDMA nor MA affected the peak amplitude of P300 ERPs. There was also no effect of Emotion on the P300 response.
MMN – Novelty processing. (Figure 4). MDMA did not affect MMN amplitude compared to PLC (no interaction between Drug and Emotion (F(3,129)= 0.91, p>.05 , ηp2=0.02) and no main effect of Drug (F(1,43)= 0.48, p>.05 , ηp2=0.01)). MA also did not affect the MMN peak amplitude (no significant interaction (F(3,129)= 0.51,p>.05 , ηp2=0.01) and no main effect of Drug (F(1,43)= 0.90, p>.05 , ηp2=0.02)). The type of face shown, however, did affect peak amplitude in PLC and MDMA sessions (F(3,129)= 39.00, p<.001 , ηp2=0.48) with Human faces resulting in a significantly greater MMN than Cartoon faces (all ps<.001). This was expected because MMN signals novel/infrequent stimuli. Similarly, in the analysis of MA vs PLC face type significantly affected MMN amplitude whereas drug type did not (F(3,129)= 37.14, p<.001 , ηp2=0.46) again with Human faces resulting in a significantly greater MMN than the Cartoon face (all ps<.001) (Figure 4).