A sudden and mysterious burst of activity originating in the retina of a developing foetus spurs brain connections that are essential to development of finely-tuned sight, Yale researchers report in the journal Nature.
Interference with this spontaneous wave of activity could play a role in neurodevelopmental disorders such as autism, the scientists speculate.
The study in mice is the first to demonstrate in a living animal that this wave of activity spreads throughout large regions of the brain and is crucial to wiring of the visual system. Without the wiring, infants would not be able to distinguish details in their environment.
''If you interfere with this activity, the circuits are all messed up, the wiring details are all wrong,'' said Michael Crair, the William Ziegler III Professor of Neurobiology and Professor of Ophthalmology and Visual Science and senior author of the study.
For instance, this activity might allow a newborn human baby to perceive such details as the five fingers attached to her hand or her mother's face. This wave wires up the visual system so that infants are poised to learn from their environment soon after birth.
The development of animals from a fertilised egg into trillions of intricately connected and specialised cells is the result of a precisely timed expression of genes.