Dopamine app:addword:noradrenalinecan precisely modify neural circuits,and th us affect behaviors.Songbirds provide an excellent model for studying the role of dopami ne in modifying circuits that underlie behavior because song learning and production are mediated by a discrete set of interconnected nuclei.We examined the effects of dopamine on synaptic inputs to the premotor robust nucleus of the arcopallium (RA) in zebra finch es using whole cell voltage-clamp recording in vitro.Dopamine was found to significantly decrease the frequencies of sEPSC/mEPSCs,but the amplitude and the kinetic properties (rise time and decay time) of the sEPSC/mEPSC were not altered by dopamine,suggestin g a presynaptic mechanism.The effects of DA were attenuated by the Dl receptor antag onist SCH23390,and mimicked by the D1 receptor agonists SKF38393,which implies that dopamine significantly suppressed excitatory synaptic transmission via activating D1 recept ors.We also find the degree of inhibition did not increase even in the high extracellular concentration of potassium ion,which would activate presynaptic voltage-dependent Ca2+ channels,implying that the inhibition effect of DA was independent of extracellular Ca2+.