Figure 4.

MDMA-induced affiliative behaviors are 5-HT_2A receptor-dependent. Average time (in min) spent huddling (a, c, and e) and average number of affiliative calls (b, d, and f) during 1-h observations following drug administration. M100907 (M100) is a selective 5-HT_2A receptor antagonist (a and b). WAY163909 (WAY163) is a selective 5-HT_2C receptor agonist (c and d). WAY100635 (WAY100) is a selective 5-HT_1A receptor antagonist (e and f). Number of sessions was between 2 and 5 for each dose. Error bars represent SEM for variation between subjects (huddling) or across sessions (vocalizations).