Drug infusion

To determine the role of cortical oxytocin receptor activation during observation of pup retrieval, we implanted cannulas in the left auditory cortex of naive virgin females¹⁵. After mice recovered from surgery, we placed them in the observational chamber, and then infused either saline or the oxytocin receptor antagonist OTA (1 µM solution in saline) through the cannula. We injected a volume of 1.5 µl at a rate of 1 µl min⁻¹. We removed the internal from the cannula five minutes after the end of injection to allow the solution to diffuse, and then allowed the virgins to acclimatize to the observational chamber for another 10 min. After this, we exposed virgins to maternal retrievals across the transparent barrier as described above. Drug conditions were compared with a survival log-rank analysis to determine effects on retrieval onset across groups.