Extended Data Fig. 4: Inverse tuning is not due to low mapping resolution.

a, Top left, schematic of regular receptive field mapping. Stimulus diameter of 20° with a grid spacing of 15°. Centre left, trial-averaged calcium responses from an example neuron for each stimulus location. Bottom left, population-averaged receptive field for responses to classical or inverse stimuli aligned to the centre of the ffRF (489 neurons in 4 mice). Right, same but for fine receptive field mapping. Stimulus diameter of 10° with a grid spacing of 5° (only for part of the visual space covered with the regular mapping, see dotted rectangle on the left). b, Top, spatial offset of regular ffRF mapping compared to fine ffRF mapping (same 489 neurons in 4 mice). The ffRF centre of each neuron estimated by the fine grid mapping is aligned at [0,0] and the localization of its estimated ffRF centre estimated by the regular grid is plotted with respect to the fine grid estimated centre. Bottom, distribution of distances between the centre of ffRF estimated by fine grid mapping and the centre estimated by regular grid mapping (approximately 90% of neurons have a distance between the two centres of less than 10°). The green symbol represents the example neuron shown in a. c, Population-averaged receptive field for responses to classical or inverse stimuli aligned to the centre of the ffRF and only for L2/3 neurons that had a preferred ffRF size of more than 15° (319 neurons in 9 mice). d, Population-averaged size-tuning functions for classical (black: L2/3 neurons with ffRF >15°, 335 neurons in 9 mice; grey: L4 neurons, 35 neurons in 6 mice) and inverse (red: L2/3 neurons with ffRF >15°, 335 neurons in 9 mice; orange: L4 neurons, 35 neurons in 6 mice) stimuli. Solid lines are fits to the data (Methods). The triangles above size-tuning functions indicate the median preferred size for each condition. Data are mean (traces or data points) ± s.e.m. (shading or error bars).