Figure 1.

GABAergic innervation in adult neurogenesis. Cartoon depiction of the stages of GC maturation highlighting the sequence of interneuron innervation. Progressive stages of GC maturation are indicated by the blue cells. Select interneurons and their axonal targeting regions are indicated by the corresponding shaded areas (red, PV⁺ basket cells; green, Ivy/NG cells; orange, axo-axonal cells). The shift in function of GABA signaling from excitation to inhibition, and the sequence and modes of signaling from interneuron subtypes are indicated in the gradient bars below. The sequence of innervation by numerous other dentate interneuron subtypes [reviewed in Houser (2007)] is not yet known so not included. SGZ, subgranule zone; GCL, granule cell layer; ML, molecular layer.