Embryonic cells communicate, even across long distances, using bioelectrical signals, and they use this information to know where to form a brain and how big that brain should be. These signals are more than an on/off switch; rather they function like software that enables a computer to carry out complex activities. Manipulating these signals can repair genetic defects and induce development of healthy brain tissue where it would not ordinarily grow. The control tadpole on the left has normal nostrils (red arrowheads), forebrain (orange brackets), midbrain (yellow brackets) and hindbrain (green brackets). In the middle tadpole, genetically defective Notch protein was injected, resulting in a severely reduced forebrain, misshapen midbrain and no nostrils. In the tadpole on the right, the research team first injected genetically defective Notch protein.