Grow-your-own synapses

Many neuroscientists are convinced that learning and experience rewire the brain, but they have never been able to observe the process. For the first time, a team of researchers has seen the formation of new synapses by using a novel technique for exciting individual neurons in culture.

To show that learning changes brain circuitry, scientists have relied on indirect evidence—before and after counts of the number of synapses in particular regions. To nab direct evidence of neural remodeling, Yukiko Goda (University of California, San Diego, CA) and colleagues used light to trigger a current through coupled neurons resting on a silicon chip. Then they observed the response of the actin cytoskeleton of the presynaptic and postsynaptic terminals, and were able to detect changes in individual synapses.

Repeated stimulation triggered action on both sides of the...