p253fig06.02 After bottom-up surface inputs activate spatial attentional cells, they send top-down topographic excitatory signals back to the surface representations.  This <I>recurrent</i> shunting on-center off-surround network contrast enhances larger attentional activities while approximately normalizing the total spatial attentional activity.  A surface-shroud resonance hereby forms that selects an attentional shroud, enhances the perceived contrast of the attended surface (light blue region), and maintains spatial attention on it.<BR>||  Surface-shroud resonance. perceptual surfaces -> competition -> spatial attention.  (Carrasco, Penpeci-Talgar, and Eckstein 2000, Reynolds and Desimone 2003)