Supplemental data

Files in this Data Supplement:

• supplemental material - Supplementary Figure S1. Traces recorded during LSPS mapping from two barrel-related cells simultaneously. The traces are arrayed as maps. The average maps corresponding to these traces are shown in Figure 4a. Only traces from a central 8 x 6 region of the mapping pattern are shown. This subregion contained traces from the key areas of input to these two cells that were near neighbors directly above a barrel, including input from L2/3, 4, and 5A, and the home barrel-related column and portions of the adjacent columns (as indicated lower right). To show the map-to-map variability for each cell, the three maps for each cell are shown individually (panels A�C for cell A, panels E�G for cell B) and superimposed (panel D for cell A, panel H for cell B). To show the cell-to-cellvariability for each mapping, the simultaneously acquired maps for the two cells are shown superimposed (I�K).
• supplemental material - Supplementary Figure S2. Correlation analysis of simultaneously recorded neighboring-neuron maps. Data are from 12 simultaneously recorded pairs of neurons (n = 72 maps, 2�6 maps per cell; 8 animals, ages P13-16). Top: Schematic depicting how map-to-map comparisons were made across maps from the same cell (black arrow), simultaneously (green arrow) or non-simultaneously (red arrow) recorded maps of a pair, and shuffled comparisons (blue arrow) of maps from different slices/animals. Bottom; Average correlation coefficients, r, for the different groups of comparisons. Comparisons within the same cell (�a�) gave highest correlation (r = 0.76 � 0.02, n = 88 comparisons), providing an estimate of the upper limit of correlation. Comparisons between simultaneously recorded pairs of maps (�b�) gave an intermediate level of correlation (r = 0.42 � 0.07, n = 35 comparisons), and comparisons for all non maps for the simultaneously recorded pairs of neurons (�c�) gave an almost identical value (r = 0.43 � 0.07, n = 44 comparisons). A lower bound for correlation was determined by shuffling maps (�d�); each map was compared to all other maps that were not from the same mapping session (i.e., that were from cells in different slices or different regions of the same slice). (�d� in Fig. 5a). The average value was 0.22 � 0.01 (n = 1177 comparisons), significantly below the pair-recorded values. Comparison of maps from different slices/animals provided an estimate of the lower limit of correlation; i.e., how much of the observed correlation was due to generic features of brain slice circuitry.