Journal: Scientific Reports

Article Title: Intrinsic motivation for singing in songbirds is enhanced by temporary singing suppression and regulated by dopamine

doi: 10.1038/s41598-021-99456-w

Figure Lengend Snippet: Effects of systemic injections of dopamine or opioid antagonists on first song latencies after 5-h LO in young adult birds. ( A ) Schedules of drug injections. Drugs or their vehicles were injected at 30-min preceding the offset of 5-h LO periods. ( B ) Comparisons of first song latencies between a dopamine D1 receptor antagonist SCH23390 with lower (0.2 mg/kg, top ) and higher (1 mg/kg, bottom ) doses and its vehicle (‘Veh’). Each line indicates a single bird. Injections of both lower and higher doses significantly increased first song latencies compared to the vehicle (* p = 0.004, significance level α was corrected to 0.0083 with a Holm-Bonferroni correction for multiple comparisons). ( C ) Comparisons between a dopamine D2 receptor antagonist haloperidol with lower (0.2 mg/kg, top ) and higher (1 mg/kg, bottom ) doses and its vehicle. Injections of the higher dose, but not the lower dose, greatly prolonged the first song latencies (* p = 0.008, corrected α = 0.0125). If no song production was observed during the post-LO period (7-h duration), the data was assigned a time of 7 h (420 min, dashed line). ( D ) Comparisons between an opioid antagonist naloxone with lower (2 mg/kg, top ) and higher (10 mg/kg, bottom ) doses and its vehicle. The effects of naloxone were not significant for either dose ( p = 0.04 and corrected α = 0.0167 for lower dose; p = 0.07 and corrected α = 0.025 for higher dose).

Article Snippet: Injected drugs and their doses were as follows: the dopamine D1 receptor antagonist R(+)-SCH23390 (Millipore Sigma, D054) dissolved in 0.9% saline (0.2 and 1.0 mg/kg); the dopamine D2 receptor antagonist haloperidol (Millipore Sigma, H1512) stored as stock solution in DMSO at − 20 °C and diluted in 0.9% saline before injection (0.2 and 1.0 mg/kg); the opioid receptor antagonist naloxone hydrochloride dihydrate (Millipore Sigma, N7758) dissolved in 0.9% saline (2 and 10 mg/kg).

Techniques: Injection