Neurons go toward the light

Like a miniature version of the famous tractor beams of sci-fi lore, beams of light known as optical tweezers have been used to hold and manipulate anything from atoms to cells. Now, Allen Ehrlicher, Josef Käs (Universität Leipzig, Germany), and colleagues show that laser beams can also manipulate a biological process—the growth of an axon.

In their new report, the authors direct axonal growth by focusing a beam of light just ahead of the leading edge of a lamellipodium. Forces of light lower than those used for optical tweezers accelerated growth at the leading edge. Shining the laser on one side of the growth cone caused filopodia to accumulate on that side, thereby initiating as much as a 90° turn of the growth cones.

Although the mechanism behind the...