A significant fraction of the cells generated in the subventricular zone (SVZ) and added in adulthood to the olfactory bulb (OB) is constituted by dopaminergic (DA) neurons. In the mammalian OB, besides mature DA neurons, confined to glomerular layer (GL), cells in which the transcription of the tyrosine hydroxylase (TH) gene occurs in the absence of significant translational activity are present in the mitral cell and in the external plexiform layers (ML and EPL). It has been proposed that these are cells recently migrated to the OB from the SVZ, and committed to become DA but not yet entirely differentiated. Using a transgenic animal model expressing GFP under TH promoter we have studied the functional properties of these cells (TH-GFP) with the patch-clamp technique in thin slices. TH-GFP cells in the EPL are autorhythmic, as are mature DA neurons, whereas TH-GFP cells in the ML are not. The pacemakers are a T-type Ca-current and a persistent Na current, the same as for mature DA neurons. The cells in the EPL are synaptically connected to the olfactory nerve, whereas those in the ML are not. Finally, the progressive maturation of the voltage dependent currents has been described. Our interpretation of these observatio ns is that TH-GFP cells outside the GL are immature DA neurons recently migrated to the OB from the SVZ, which disrupt their migration at the level of the ML, and send a dendritic process towards the GL trying to establish a synaptic contact. Only when/if this attempt succeeds, the TH-GFP cells receive some kind of consensus signal from the GL allowing them to ful fill their differentiation towards the DA phenotype and to complete their migration on the way to their final destination crossing the EPL.