Figure 2.

Spatial frequency tuning of Y-cell linear and nonlinear responses. A, SF tuning of an LGN Y-cell. Responses to drifting sinusoidal gratings are used to define a linear SF tuning curve (solid black curve). Responses to contrast-reversing gratings are used to define a nonlinear SF tuning curve (solid gray curve). Also see supplemental Figure 1 (available at www.jneurosci.org as supplemental material). Baseline firing rate is indicated by the dotted black line. Error bars show SEM. Arrows mark the envelope and carrier spatial frequencies of the interference patterns used to study the neuron's non-Fourier responses. Note that at high spatial frequencies, the neuron responded to contrast-reversing gratings but not drifting gratings. B, Histogram of the preferred linear and nonlinear spatial frequencies of Y-cells.