Example recording sessions. A–D, Data from site 22 for texture, shape, drifting grating, and translational motion stimuli (columns) are shown. A, Each panel shows mean normalized activity (in the 0–1 range, see scale bar) of simultaneously recorded neurons (x-axis) across stimulus conditions (c-axis; see Fig. S1 for details of the normalization procedure). Texture includes 120 conditions (0–39, original; 40–79, contrast-reversed; 80–119, spectrally matched noise). Shape has 50 conditions (0–49). Drifting grating comprises 60 conditions (5 spatial frequencies × 12 directions spaced 30° apart, with 0–4 being spatial frequencies at direction 0°). Translational motion includes 40 conditions (5 spatial displacements × 8 directions spaced 45° apart, with 0–4 being displacements at direction 0°). A horizontal stripe pattern (green and orange arrows in drifting panel) indicates that multiple nearby neurons exhibit similar visual feature tuning. B, Pairwise tuning similarity between neurons is shown, with unit IDs on both axes. Color scale indicates the strength and sign of similarity, where red and blue represent positive and negative values for the Pearson’s correlation coefficient (r). Diagonal entries were replaced with NaNs and displayed in gray. C, The x-axis represents unit IDs, and the y-axis values correspond to the distance from unit# 0, defined as the neuron recorded closest to the probe tip. Neurons with similar tuning were organized into groups using clustering analysis (see Materials and Methods). The four panels display the same neurons, but colors represent different functional clusters for each stimulus type: orange marks the largest cluster. Neurons that do not belong to any cluster are represented in gray. D, Scatterplots comparing responses of a pair of example neurons. Data are the same as depicted in the corresponding columns of the normalized response matrix in A. These two units exhibited a positive correlation for texture responses but not for other stimulus classes (see pairwise tuning similarity matrix in B). E–H, Results from site 09. The conventions are the same as those in A–D.
