Fig 1.
A) Radial frequency patterns with different radial frequencies (3–6) and amplitudes (A1-4). B) All the different shapes were presented in four different orientations (polar phases 0, 90, 180 or 270 deg). In total, 65 different stimuli were used, circles and 64 modulated shapes (4 RFCs x 4 amplitudes x 4 orientations). C) RFC patterns are constructed by modulating a base circle with radial sine function. D) The concave and convex curvatures were calculated at the trough and peak, respectively, of the modulation function. Amplitude refers to the amount of modulation relative to the radius of base circle.
Fig 2.
A) Within the searchlight, t-value for average activity across different modulated shapes was calculated for each voxel and for each participant. Median t-values across participants are shown on the flattened Freesurfer average surface. Left and right hemispheres are on the left and right sides, respectively. B) Signal changes for circles and modulated shapes in different visual areas. C) Signal changes as a function of local curvature. Value 0.35 depicts circle shape. D) Signal changes as a function of radial frequency in different visual areas.
Table 1.
Statistical tests.
Fig 3.
The RDMs describe the dissimilarity of the response patterns across different shapes. Five models were constructed based on the classification of the stimuli to four classes (Table 2) and one model was constructed by cross-correlating stimulus SF spectrum. Model RDMs for Radial Frequency, Amplitude, Convex Curvature, Contrast Energy, Spatial Frequency Spectrum, and Concave Curvature, and one example of the measured RDM from visual area V3AB. See S1 Fig for examples of measured RDMs in all areas.
Fig 4.
Correlation maps for Radial Frequency (A), Amplitude (B), Convex Curvature (C), Concave Curvature (D), Spatial Frequency spectrum (E), and Contrast Energy (F). Within the searchlight, correlation with model RDMs was calculated for each voxel. Average correlations, larger than three standard deviations above the mean, across participants are shown on the flattened Freesurfer average surface. Left and right hemispheres on the left and right sides, respectively.
Fig 5.
A) Average correlations with Radial Frequency model for different visual areas in the left and right hemispheres. B) Average correlations with all models. Hemispheres have been averaged. Error bars depict standard error of mean across participants. C) Dorsal-Ventral difference. Average correlation difference between dorsal (V2d, V3d, V3AB, IPS0) and ventral (V2v, V3v, hV3, VO1) visual areas for model RDMs. *p < .05 (t-test).
Table 2.
Stimulus parameters and classifications in model RDMs.