Figure 9.

Receptive field structure of orientation/axis-selective RGCs. A–C, Examples of RF structures (left) and tuning curves (right). Contours of fitted Gaussians at 2× SD were superimposed (black line). The radius of the polar plot represented 8.0, 20.8, and 2.1 spikes/s, respectively. D, Distribution of RF aspect ratio. Cells were classified into circular (green) or elongated (red) by the same criteria used for dLGN analysis (cutoff of 1.3). E, No correlation between the RF aspect ratio and the difference between the preferred orientation and RF orientation (n = 101, correlation coefficient = −0.1, p = 0.43). F, Possible emergence of orientation selectivity in the dLGN by converging two direction-selective RGCs that have asymmetric excitation/inhibition in their RFs. The dLGN cell could be orientation selective to flashed bars due to its elongated inhibitory RF.