Most parents’ first glimpse of their children comes in ultrasound images taken months before birth. But ultrasound could soon offer much more than prenatal portraits. In the past few years, researchers have opened a new door for ultrasound, developing techniques that harness the familiar, safe and noninvasive sound waves to control genes, alter brain function and deliver drugs to targets with millimeter precision.

The advance of what’s being termed sonogenetics offers a new twist on o