Fig. 4: Region-based feature coding of MTL neurons in the VTC neural feature space.
From: Computational single-neuron mechanisms of visual object coding in the human temporal lobe
a VTC neural feature space constructed using all axis-coding channels in the FG. All stimuli are shown in this space. b, c Two example MTL neurons that encoded a region in the VTC neural feature space. (left) Neuronal responses to 500 objects (50 object categories, with 10 images per category). Trials are aligned to stimulus onset (gray line) and are grouped by individual object category. Boxes indicate the 25th–75th percentiles with the median line, whiskers show non-outlier ranges, and circles mark outliers. (middle) Projection of firing rates onto the feature space, with each color representing a different object category. The size of the dot indicates firing rate. The coding regions are delineated with encompassed object images and categorical labels in the insets, with text size proportional to the number of encoded stimuli within each category. (right) Estimate of the spike density in the feature space. By comparing observed (upper) versus permuted (lower) responses, we could identify a region (black contour in the middle panel) where the observed neuronal response was significantly higher in the feature space. This region was defined as the tuning region of a neuron. Images were obtained from Deng J, Dong W, Socher R, Li L-J, Li K, Fei-Fei L (2009). IEEE Conference on Computer Vision and Pattern Recognition 2009: 248–55. IEEE. d–i Population summary of MTL region-coding neurons. d Percentage of region-coding neurons in each MTL ROI. e The number of categories encoded by region-coding neurons. f The number of objects encoded by region-coding neurons (i.e., the number of object images that fell within the tuning region of a region-coding neuron). PH: n = 18. AH: n = 23. amygdala: n = 65. Legend conventions for box plots as in (b, c). g–i The population aggregated tuning region in each MTL ROI. Color bars show the counts of overlap between individual tuning regions. Numbers in the density maps show the percentage of the VTC neural feature space covered by the tuning regions of the total observed region-coding neurons. Source data are provided as a Source Data file.
