Whole-cell perforated-patch recording in slices revealed synaptic organization of the intermediate medial hyperstriatum ventrale, a telencephalic region intimately involved in the early learning processes in chicks. Local electrical stimuli elicited excitatory post-synaptic current (EPSC) mediated by monosynaptic activation of glutamate receptors of the non-N-methyl-D-aspartate type, which was followed by a late GABAA-ergic inhibition. The initial EPSC was potentiated at least for 60 min, when a tetanic stimulation (5 Hz x 60 s) was combined with post-synaptic depolarization at or above -30 mV. In some of these neurons, the potentiated responses underwent a subsequent depression when a second tetanus was accompanied by hyperpolarization at -80 mV or below.