p360fig10.09 Perceptual grouping is carried out in layer 2/3 by long-range horizontal excitatory recurrent connections, supplemented by short-range disynaptic inhibitory connections that together realize the bipole grouping properties that are diagrammed in Figure 10.10.<BR>||  Grouping starts in layer 2/3. LGN-> 6-> 4-> 2/3: 1. Long-range horizontal excitation links collinear, coaxial receptive fields (Gilbert, Wiesel 1989; Bosking etal 1997; Schmidt etal 1997)  2. Short-range disynaptic inhibition of target pyramidal via pool of intraneurons (Hirsch, Gilbert 1991)  3. Unambiguous groupings can form and generate feedforward outputs quickly (Thorpe etal 1996).