Article Figures & Data
Figures
- Figure 1.
A, A perspective view on the grid of stimulus positions, and the stereoscopic sphere composed of colored dots, used to map position selectivity in retinotopic regions of visual cortex. The black points and the black box outlining the fixation point are for display purposes only, subjects only saw the sphere and the gray fixation point on a black background in the actual task. B, The same example grid in OpenGL units. The size of the sphere, shown in red, was scaled with z position to maintain the same apparent size throughout. C, Comparison of stimulus grid when plotted in units of physical position or disparity. Stimuli in each row of the grid share a physical z position (top panel), which results in a curved grid with nonlinear spacing when units are converted to disparity (bottom panel). This also results in a nonlinear spacing of the rows along the disparity axis. D, Subjects performed a demanding contrast change detection task at fixation throughout all imaging runs; average accuracy on this task is plotted. Individual points indicate single subjects, error bars indicate mean ± SEM. For a plot of task performance broken down by the depth position of the stimulus, see Extended Data Figure 1-1.
- Figure 2.
Average six-way decoding performance in the z dimension. Performance (d’) values were averaged across subjects and error bars indicate SEM. Filled circles over individual bars indicate above chance decoding after FDR correction at q = 0.01. Asterisks indicate significant differences at the 0.05 (*), 0.01 (**), and 0.001 (***) significance levels, respectively. Pairwise comparisons were corrected using Tukey’s method; for details, see Materials and Methods.
- Figure 3.
SVM classifier performance (d’) depends on difference in stimulus disparity between the positions of interest. A, Each unique pair of the six stimuli in depth is plotted on the abscissa, with small disparity differences indicating that the stimuli were close together in the z dimension. Blue lines depict the fit to the mean bootstrapped across subjects, and asterisks (*) indicate a significantly positive slope (FDR q = 0.01). Filled and open circles above individual error bars indicate significance after FDR correction at q = 0.01 and q = 0.05, respectively. For the same data plotted as a dissimilarity matrix, see Extended Data Figure 3-1. B, Bootstrapped distribution of slopes for the relationship between classifier d’ and the disparity difference between the positions of interest. Filled gray circles indicate slopes significantly above 0 (FDR q = 0.01).
- Figure 4.
Average model-based representation of stimuli at each position along the x (blue-green) and z (purple) dimensions. Vertical lines indicate where the stimuli were presented along the x- or z-axis. The curved lines in matching colors indicate representations of the corresponding positions.
- Figure 5.
Best fit centers of model-based representations at each stimulus position versus actual displayed stimulus center (thin gray line). Average fit center across participants shown in black solid lines, with 95% CIs computed by bootstrapping. Individual participants are shown in colored circles. Mean linear regression solution is shown with a dotted black line, where high accuracy representations have a dotted line that overlaps with the gray line.
- Figure 6.
Quality of model-based representations assessed three ways. A, Absolute error between the true stimulus position and the estimated position for both x (left) and z (right). B, Best-fit amplitude of representations, averaged across position. In both A, B, open black circles and solid black lines indicate mean and 95% CIs computed by bootstrapping. Individual participants are shown in colored circles. Asterisks in the rightmost panels indicate differences significant at the 0.01 (**) or 0.001 (***) significance level. Note that no pairwise tests were performed for the left panels of A, B, C. Bootstrapped distribution of linear regression slopes from data in Figure 5. This represents the intersubject variability of the slopes. Daggers (†) indicate differences significant at the 0.05 level before FDR correction. For plots of representation fit size and baseline, see Extended Data Figures 6-1, 6-2.
Tables
z position (OpenGL) Average disparity (arcmin) –1.5 38.6 –0.9 25.6 –0.3 11.1 0.3 –5.2 0.9 –23.6 1.5 –44.6 Since disparity within each z position varied slightly with eccentricity (e.g., more peripheral positions appear further from the observer), we report the average value of disparity across each row of the grid shown in Figure 1. For individual values of disparity, see Extended Data Table 1-1.
Extended Data Figure 1-1
Task performance was not significantly affected by disparity of the stimulus. Subjects performed a demanding contrast change-detection task at fixation throughout each imaging run, and performance did not change as a function of stimulus disparity. Black line shows mean ± SEM, colored lines show individual subjects. Download Figure 1-1, EPS file.
- Extended Data Table 1-1
Actual values of position in OpenGL space, degrees visual angle, and disparity for each position in the stimulus grid Download Table 1-1, DOC file.
Extended Data 1
Analysis code can be accessed by downloading the zip file associated with this manuscript. See the README file in this folder for details. Download Extended Data 1, ZIP file.
Extended Data Figure 3-1
Dissimilarity between all pairs of Z positions. Color of each square indicates the performance (d’) of a linear classifier trained to discriminate between the positions of interest. Solid and open circles indicate above-chance decoding performance at the 0.01 and 0.05 significance levels, respectively. High values in the bottom row of each plot indicate that the nearest Z position (–44.6 arcmin) was the most easily discriminated from other positions. Download Figure 3-1, EPS file.
Extended Data Figure 6-1
Additional parameters of best-fit curves for model-based representations of stimulus X and Z position. A, Fit baseline. B, Fit size. In all plots, mean and confidence intervals across participants shown in black solid lines, with 95% CIs computed by bootstrapping. Individual participants are shown in colored circles. Download Figure 6-1, EPS file.
Extended Data Figure 6-2
Parameters of best-fit curves for model-based representations, plotted as a function of stimulus position along z-axis. Values are averaged across all brain regions. A, Absolute value of fit center error. B, Fit size. C, Fit amplitude. D, Fit baseline. In all plots, mean and confidence intervals across participants shown in black solid lines, with 95% CIs computed by bootstrapping. Individual participants are shown in colored circles. Asterisks indicate differences significance at the 0.05 (*), 0.01 (**), or 0.001 (***) significance level. Note that no pairwise tests were performed for panels B, D; for details, see Materials and Methods. Download Figure 6-2, EPS file.
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