Test for multiplicative scaling of mEPSC amplitudes with a rank-order plot of amplitudes.

<p><b>A.</b> mEPSCs were recorded from CA1 pyramidal neurons in slice cultures of rat hippocampus. For induction of homeostatic plasticity of synapses, slice cultures were treated with 1–1.5 µM TTX for 3–4 days. Rank-ordered amplitudes of mEPSCs in TTX-treated cells were plotted against rank-ordered control mEPSCs. A total of 700 mEPSCs, with 100 events per cell, were collected. The straight lines are linear fits with variable (blue) or zero (green) <i>y</i>-intercept. <b>B.</b> Cumulative histograms of mEPSC amplitudes. Individual mEPSC amplitudes in TTX-treated cells were transformed with the equation <i>y</i> = 1.6<i>x</i>–4.9. The distribution of transformed values almost exactly overlaps the control distribution. The <i>p</i> value is from a K-S test between control and scaled TTX group. <b>C.</b> Cumulative histograms were obtained as in B (control and TTX plots are the same as those in B), but the TTX group was scaled with the equation <i>y</i> = 1.27<i>x</i>. The <i>p</i> value from a K-S test shows significant differences between control and scaled TTX groups. <b>D.</b> mIPSCs were obtained from control and TTX-treated slice cultures of hippocampus. The rank-order plot (D) and the cumulative histograms (E,F) were constructed in a similar manner to those in A–C. <b>E.</b> Cumulative histogram of mIPSC amplitudes. The amplitudes of TTX-treated mIPSCs were transformed with <i>y</i> = 0.55<i>x</i>–7.4. Again, the transformed distribution shows nearly complete overlap with the control distribution. The <i>p</i> value is from a K-S test between control and scaled TTX group. <b>F.</b> The TTX group was scaled with the equation <i>y</i> = 0.60<i>x</i>. The distributions of the control and scaled TTX groups are significantly different from each other (K-S test).