Fig. 1: Sparse visual responses to natural images.
a Experimental schematic. Natural images are presented, and the activity of V1 neurons was recorded using two-photon Ca2+ imaging. b Examples of trial-averaged visual responses. The three lines for each response indicate the mean and the mean ± S.E.M. Black: significant responses, gray: non-significant responses, and red: stimulus periods. c Significant response events in an example plane (upper left). Bottom: the percentage of responsive cells for each image. Right: the percentage of images to which each cell responded. Red lines (bottom and right) indicate median values. d Examples of population response patterns to three images. Left: stimulus images and the spatial distributions of cells in an imaging area (side length: 507 microns). The red-filled and gray open circles indicate the responsive and remaining cells, respectively. Right: histograms of the visual responses to images presented in the left panels. Cells are divided into responsive (red) and the remaining groups (black), and are sorted in each group by the response amplitude to the image presented in the top row. The cell number order is fixed among the three histograms. e Distribution of the amplitude of responses to single images. The cell # is sorted by the amplitude of the response to each image and averaged across images in a plane. After normalizing the cell # (x-axis), data were collected across planes. The median (thick line) and 25–75th percentiles (thin lines) are shown. f Percentages of visually responsive cells. g Percentages of responsive cells per image. h Percentages of responsive cells for the moving grating. i Percentages of responsive cells for each direction of the moving grating. j Percentages of overlap of responsive cells between the natural images. k Population sparseness. f–k Each dot indicates data obtained from one plane, and the medians across planes are shown as bars. e–g, j, k N = 24 planes. h, i N = 23 planes (one plane data were discarded because of FOV drift during imaging). The stimulus images in a and d are adapted from the databases in refs. 56,57 with permission. Source data are provided as a Source Data file.
