Correction

NEUROSCIENCE. For the article “Motility of dendritic spines in visual cortex in vivo: Changes during the critical period and effects of visual deprivation,” by Ania Majewska and Mriganka Sur, which appeared in issue 26, December 23, 2003, of Proc. Natl. Acad. Sci. USA (100, 16024-16029; first published December 8, 2003; 10.1073/pnas.2636949100), the authors note the following printer's error. The second sentence in Methods under the subheading “Surgical Preparation for in Vivo Imaging” should have read that the mice were “anesthetized with avertin” instead of “killed by using avertin.” This error is significant because it changes the intended meaning of the paper, which was to image these structures in live animals rather than in a fixed section of brain slices. This correction does not affect the conclusions of the article.