Primary cilia are typically solitary, microtubule-based appendages that project from the surface of nearly every cell type in the human body, including most neurons throughout the brain. The primary cilium is thought to act as an antenna surveying the extracellular milieu, receiving various signals, and transmitting those signals into the cell. For example, the outer segment of photoreceptors, which is a modified cilium, mediates vision by sensing light. Olfactory cilia mediate olfaction by sensing and responding to odorants. Defective formation or function of primary cilia is implicated in the pathogenesis of many human developmental disorders and diseases, collectively termed ciliopathies. Ciliopathy patients display a range of neurological disorders (Lee and Gleeson, 2011), including cognitive deficits and behavioral phenotypes, thereby highlighting the importance of primary cilia function within the brain (Figure 1).