Neural correlates of sparse coding and dimensionality reduction
Fig 6
(A and B) Distribution of 3D direction preferences of MSTd-like model units in the NSC-based sparse decomposition model (rotation, [A]; translation, [B]). Each data point in the scatter plots corresponds to the preferred azimuth (abscissa) and elevation (ordinate) of a single neuron. Histograms along the top and right sides of each scatter plot show the marginal distributions. Also shown are 2D projections (front view, side view, and top view) of unit-length 3D preferred direction vectors (each radial line represents one neuron). (C) Distribution of FOE & P selectivities in macaque MSTd (dark gray) and model MSTd (light gray). Neurons or model units were involved in encoding heading (FOE), eye velocity (P), both (FOE & P), or neither (none). (D) Heading prediction (generalization) error as a function of the number of basis functions using cross validation. Vertical bars are the SD. FOE, focus of expansion; MSTd, dorsal subregion of the medial superior temporal area; NSC, nonnegative sparse coding; P, pursuit. Reprinted with permission from [46].