Figure 5.

Endogenous activation of oxytocin-like receptors promotes preferences for larger groups. (A) Choice apparatus design. A 1-m wide testing cage was subdivided into zones by seven perches (thin lines). Subjects were considered to be within close proximity when they were within 6 cm of a stimulus cage (i.e., on the perches closest to the sides of the testing cage). The stimulus cages contained either 2 or 10 same-sex conspecifics. (B–E) Relative to vehicle treatments, subcutaneous (s.c.) or intracerebroventricular (i.c.v.) administrations of the oxytocin antagonist desGly–NH₂, d(CH₂)₅[Tyr(Me)², Thr⁴]OVT (OTA; 250 ng), reduce the amount of time that zebra finches spend in close proximity to the large group (B,C) and increase time in close proximity to the small group (D,E). *P < 0.05, ***P < 0.001, main effect of Treatment; #P < 0.5 Sex*Treatment; n = 12 m, 12 f. Letters above the error bars denote significant within-sex effects. Modified from Goodson et al. (2009c).