Figure 1.

Combinatorial approach to study and classify postnatally generated cortical interneurons. A, Postnatally born cells originating in the SVZ were identified and staged in 5HT₃-EGFP mice that were injected with a retroviral vector (red stars) expressing RFP in newborn cells. B, Control injection of the retrovirus-RFP in a P4 wt mouse showing that 3 d after injection fluorescence is confined to the injection area, the SVZ and the RMS. C–E, Based on their location, morphology and firing pattern, postnatally generated neurons (red dots) were classified into five stages, and from stage 3 onwards could be divided in two categories, small axonless neurons (E, left panels) and multipolar neurons (E, right panels). Two representative examples of each cell type at stage 5 (axon in red, dendrites in black) and their typical firing pattern in response to a 1 s depolarizing step in current-clamp are presented at the bottom. OB, Olfactory bulb; LV, lateral ventricle; Hip, hippocampus.