Endogenous neural precursor cells in health and disease

•Neural precursor cells accomplish important functions for brain tissue homeostasis.•Neural precursor cells provide new cells for the olfactory bulb and hippocampus (neurogenic role).•Neural precursor cells regulate brain functions through the release of soluble factors (non-neurogenic role).•In pathological conditions, neural precursor cells contribute to restraining tissue damage.•Neurodegenerative diseases and physiological aging are accompanied by neural precursor cell dysfunctions.