Cover legend: Temporal evolution of human V1 activation measured by fMRI while the subject saw a target grating surrounded by grating whose contrast was periodically and continuously modulated. Each curve represents the BOLD response of a voxel fitted by a sinusoidal function. The dark and bright traces show the responses of cortical areas corresponding to the stimulus center and surround, respectively. The activation of two areas were negatively correlated when the center had high contrast (upper), and were negatively correlated when the center had low contrast (lower). For more information, see the paper by Tajima et al. in this issue (pages 3264–3270).