Contents

21 September 1990
Vol 249, Issue 4975

About The Cover

In adult zebra finches (a male is shown here) and canaries, new projection neurons are formed in the high vocal center, a region of the brain. Species differences in the number of projection neurons added and the time when these additions occur suggest that these new neurons are involved in perceptual and motor song learning. See page 1444. [Photograph by A. Alvarez-Buylla]