Transgenic non-human animal models are described that allow for the fate mapping and identification of cells that respond to hedgehog signaling in vivo during a particular time period. More particularly, these animal models and cells obtained from these animal models may be used to screen for agonists or antagonists of the Hedgehog signaling pathway. Thus, these transgenic animal models allow for the identification of HH agonists or agents that may enhance neurogenesis or for HH antagonists or agents that may be potentially useful for treating cancers or hyperproliferative conditions associated with high levels of hedgehog expression.