Most of the complex brain circuitry responsible for our ability to perceive the world with precision actually develops in the womb, before sensory experience is even possible. For instance, visual circuits responsible for our ability to perceive depth and see shapes and colors are already well formed at birth, however visual deprivation later in life leads to permanent blindness. Similarly, children are born with the ability to perceive a full complement of sounds but it is only later in life that they lose the ability to distinguish sounds that are unfamiliar in their native tongue. This implies that intrinsic mechanisms, apart from sensory experience, are responsible for wiring the complex brain circuits mediating basic perception. Research in the Crair Lab examines the limits and links between genetic mechanisms and spontaneous or intrinsic neuronal activity in wiring the brain during development. The Crair Lab uses a broad array of experimental approaches, from gene expression analysis to optical imaging and stimulation in living organisms to study the properties, role and mechanisms of spontaneous neuronal activity in guiding neural circuit development. The research suggests that the remarkable development of complex brain circuitry that occurs in the womb is due, in part, to the generation of complex and patterned spontaneous activity in the peripheral nervous system that then spreads into and through the brain, wiring it along the way. Disruption of this ongoing activity may play an important role in neurodevelopmental disorders such as amblyopia and autism.