Figure 7.

Push-pull effect. (A) Some examples of ${\text{A}}_{\text{ON}}^{\text{u},+}$ and ${\text{A}}_{\text{OFF}}^{\text{u},-}$. Each block on the left is a 16 × 16 image that represents 256 excitatory connections from ON LGN cells to a simple cell. Each block on the right represents inhibitory connections from OFF LGN cells to a simple cell. The color magenta represents excitatory connections; the color green represents inhibitory connections. (B) Red and blue contours represent excitatory connections from ON LGN cells (${\text{A}}_{\text{ON}}^{\text{u},+}$) and inhibitory connections from OFF LGN cells (${\text{A}}_{\text{OFF}}^{\text{u},-}$), respectively. Connections that are smaller than 20% of the maximal connection were removed to only show substantial weights. The number in each block indicates the push-pull index. (C) Histogram of the push-pull index for simple cells in cat V1. Re-plotted from Figure 4B in Martinez et al. (2005). (D) Histogram of the push-pull index for model simple cells. (E) Synaptic fields of the six simple cells with push-pull index larger than 0.2.