HTR1B and major depressive disorder: In addition, we found that the changes of FC in MDD patients after ECT compared to before treatment were negatively correlated with the density of the receptors/transporters of serotonin (5‐HT1B: r = −0.26), acetylcholine (α4β2: r = −0.22), histamine (H3: r = −0.17) and glutamate (NMDAR: r = −0.13) (Figure 6B).