Developmentally restricted synaptic plasticity in a songbird nucleus required for song learning

We provide evidence here of long-term synaptic plasticity in a songbird for ebrain area required for song learning, the lateral magnocellular nucleus o f the anterior neostriatum (LMAN). Pairing postsynaptic bursts in LMAN prin cipal neurons with stimulation of recurrent collateral synapses had two eff ects: spike timing- and NMDA receptor-dependent LTP of the recurrent synaps es, and LTD of thalamic afferent synapses that were stimulated out of phase with the postsynaptic bursting. Both types of plasticity were restricted t o the sensory critical period for song learning, consistent with a role for each in sensory learning. The properties of the observed plasticity are ap propriate to establish recurrent circuitry within LMAN that reflects the sp atiotemporal pattern of thalamic afferent activity evoked by tutor song. Su ch circuit organization could represent a tutor song memory suitable for re inforcing particular vocal sequences during sensorimotor learning.