Surviving to remember

Not all memories live forever. Some memories may, at least in birds, die with the death of the neurons that encode them. Now, Benjamin Alvarez-Borda, Bhagwattie Haripal, and Fernando Nottebohm (Rockefeller University, New York, NY) suggest that the life expectancy of certain canary neurons, and perhaps of their associated memories, depends on one factor.

Canaries start singing and learning songs in the fall as the mating season approaches. Neurons entering the high vocal center (HVC) during this time stick around so that song memories persist. But by spring most of the birds have found a mate and ignore singing in favor of other pursuits. Neurons born in the spring come and go more rapidly.

The Rockefeller team turned the short-lived spring neurons into long-lived neurons by a short burst of...