Erratum: The illustration of the hippocampal CA1 dendritic segment featured on the cover of the January 1, 1997 issue was inadvertently printed upside down. This image, provided by Spacek and Harris, was intended to be viewed as shown in the accompanying illustration.
Cover picture: Smooth endoplasmic reticulum (purple) of a hippocampal CA1 dendritic segment enters the thin neck of a large dendritic spine (gray) that has a highly irregular postsynaptic surface (red). The SER in the head of the spine (seen in the lower figure where the spine is invisible) is thought to provide synapse-specific regulation of calcium and other molecules. See the article in this issue by Spacek and Harris (pp. 190–203).