Figure 2.

Modulation of SCN Firing by Drifting and Inverting Gratings

(A–D) Single-unit data, n = 24 from six mice. (A) Raster and perievent histogram responses of a representative unit to inverting gratings (∼4 Hz; depicted in cartoon form above) as a function of spatial frequency (figures to left in cycles per degree [cpd]) are shown. Red lines indicate ± 3 SDs of mean firing rate across cycle; inversions are at 0 and 0.125 s. (B) Proportion of cells with full-field (n = 8) or “other” (n = 16 either ON center or center:surround) RFs with significant modulations in firing at the grating inversion frequency (spectral power analysis) as a function of spatial frequency is shown. (C) Perievent histograms and rasters over two stimulus cycles (arrows depict inversion times) for two example units exhibiting frequency doubling are shown. (D) The range of spatial frequencies (cpd) over which the seven cells that show frequency doubling responded (black lines) and exhibited frequency doubling (red bar) is shown.

(E) Raster plot for a representative unit under 4-Hz 0.03-cpd stimulus (depicted in cartoon form above).

(F) Firing rate profiles (mean ± SEM 5-min presentation) for a representative unit over a range of spatial (left) and temporal (right) frequencies.

(G) Heatmap (scale to right) of the proportion of cells (n = 23 single units from eight mice) tracking (power at F1 or F2 peak > 4 SDs above the mean) drifting grating at each spatiotemporal frequency.

(H) Heatmap (scale to right) of mean modulation index across the population at different spatiotemporal frequencies (modulation index set to 0 for units without significant response to stimulus).

(I) Firing rate profiles (mean ± SEM 1,200 repeats) over a range of spatial frequencies for a unit with spatial band pass behavior.

See also Figures S1 and S2.