Development Of A Novel Model: Using Songbirds To Elucidate The Pro-Neurogenic Role Of Microglia In Healthy And Natural Neurodegenerative States

Inflammatory cells like microglia exert beneficial effects on neuronal survival, synaptic maintenance, and circuit plasticity. Most research has focused on neural injury or insult; roles in normal development and homeostasis remain less clear. To characterize the behavior of microglia under non-pathological conditions, we exploit seasonal death and replacement of neurons in a sensorimotor brain region responsible for singing behavior in white-crowned sparrow, Zonotrichia leucophrys. The song control nucleus HVC incorporates 50,000 new projection neurons into an existing pool of 100,000 neurons within one week of transitioning to breeding conditions. Within four days of transitioning back to nonbreeding conditions, an equal number of HVC neurons dies. Seasonal neuronal death in HVC increases neural stem cell proliferation in the adjacent ventral ventricular zone. This growth and regression correlates to …