Figure 1.

Stimulus composition. Texture patterns (herringbones) were composed by periodic modulation of two orthogonal static luminance gratings (carriers) by two drifting gratings (modulators). A fixed orientation difference of ±45° separated modulator and carrier patterns, and was used to distinguish neuronal responses to each. A, D, Low spatial frequency drifting gratings used to modulate the carrier patterns (modulators M and its inverse −M). B, C, High spatial frequency static gratings used as carrier patterns. To produce the texture pattern, each carrier was multiplied by a modulator (carrier 1 with modulator M; carrier 2 with modulator −M). E, F, The resulting contrast-modulated carrier patterns. G, The final herringbone texture pattern was generated by combining the patterns in E and F additively; the modulator orientation (here vertical) defined the orientation of the texture-defined form.