<p>Shown is the percentage of fractional weights stronger than a threshold, as a function of the threshold used, separated in two panels for clarity, for (dark blue) mouse intrahemispheric, (light blue) mouse interhemispheric and (green) multi-experiment macaque intra-hemispheric connections. The thick solid lines give the density of thresholds for all connections. This distribution is wide for mouse (blue), which features both high-weight co-injection thresholds and low-weight region-specific noise thresholds. It is much narrower for macaque (green), as the threshold is 1/(number of neurons measured per experiment), which changes over only one order of magnitude between experiments. The dashed vertical lines give an estimated lower bound of the mean contribution of a single projecting neuron, for (blue) mouse and (green) macaque.</p
