Neurogenesis in the adult brain has been a field of growing interest. There are two neurogenic niches in the mammalian adult brain: subgranular zone (SGZ) of the hippocampus and the subventricular zone (SVZ), producing new neurons that use the rostral migratory stream (RMS) to reach olfactory bulb (OB). Cells in these two discrete regions retain the capacity to generate multiple lineages in vitro and in vivo. Thus far, the mechanisms involved in the regulation of these cells have not been well elucidated, once the underlying cellular signaling mechanism is not fully understood. The aim of this work is to collect the most recent papers published in this field to elucidate the signaling pathways involved in the adult “up” and “down” neurogenesis. The most cited pathways included directly or indirectly associations with neurotrophins and transcription factors. This work provides a schema showing the outline from “macro” to “micro” signaling for neurogenesis in the SGZ of the hippocampus. It also includes a session linking neurogenesis to the pathophysiology of mood disorders and stress-related cognitive dysfunctions. Further characterization of these molecular components could provide greater insight into the mechanisms involved in the regulation of neurogenesis in the adult brain.