Activation of presynaptic GABAB receptors modulates GABAergic and glutamatergic inputs to the medial geniculate body

► Activation of presynaptic GABAB receptors by baclofen suppresses synaptic transmission to the MGB. ► Glutamatergic synaptic transmission is more potently suppressed by baclofen than GABAergic synaptic transmission. ► GABAB receptors at GABAergic presynaptic terminals are activated by endogenously released GABA in an age-dependent manner.