Figure 2.

Plot of PSD size versus number of AMPAR nanoclusters. PSD sizes were measured from PSD-95 staining using dual-colour dSTORM [14]. The black line is a linear model based on the assumption that synapses are composed of an integer number of modules, each containing matrix material and a single AMPAR nanocluster. Filled circles represent synapses containing AMPAR nanoclusters, and open circle corresponds to silent synapses. Each module is approximately 0.06 µm² (approx. 276 nm in diameter). The figure is plotted from data in [14]. Error bars indicate cell-to-cell variability. Alternatively, all data points (silent synapses and functional synapses) in figure 2 can also be fitted by a single line as originally done in [14], leading to a module size of approximately 0.04 µm², which is even smaller than the size of silent synapses. However, as will be described later, other evidence also suggests that silent synapses should be treated as a separate group and should thus be excluded from the linear fit of synapse sizes.