p354fig10.01 The lamiar cortical circuit that realizes how we pay attention to an object sends signals from layer 6 of a higher cortical level to layer 6 of a lower cortical level and then back up to layer 4.  This "folded feedback" circuit realizes a top-down, modulatory on-center, off-surround circuit that realizes the ART Matching Rule.<BR>||  Top-down attention and folded feedback. Attentional signals also feed back into 6-to-4 on-center off-surround. 1-to-5-to-6 feedback path: Macaque (Lund, Booth 1975) cat (Gilbert, Wiesel 1979).  V2-to-V1 feedback is on-center off-surround and affects layer 6 of V1 the most (Bullier etal 1996; Sandell, Schiller 1982).  Attended stimuli enhanced, ignored stimuli suppressed.  This circuit supports the predicted ART Matching Rule! [LGN, V[1,2][6->1]]