Cover legend: Astrocytes in the stratum radiatum of mouse hippocampus just below CA1 pyramidal cells express a large number of Cx43 gap junctions (yellow puncta). Astrocytes have been labeled using antibodies to GFAP (blue), and nuclei were stained with DAPI (purple). Illustration credit: Xiaoning Han and Takahiro Takano. For more information, see the article by Lin et al. in this issue (pages 681–695).