Cover legend: In vivo intracortical imaging of astrocytic calcium dynamics during spreading depression using two-photon microscopy (160 µm below the cortical surface of a rat). Astrocytes were loaded with SR-101 (red) and the calcium indicator Fluo-4-AM (green). The vascular compartment was loaded with FITC dextran (green). The projected shadows of major surface vessels are clearly seen. This study demonstrates that large astrocytic calcium waves trigger the initial hemodynamic change observed in spreading depression. For more information, see the article by Chuquet et al. in this issue (pages 4036–4044).