Figure 4. Accuracy of the I_mean method for detecting changes in the phasic current.

CA1 PC recorded in the presence of 3 mm kynurenic acid and 5 μm GABA at two separate holding potentials of −60 and −13 mV. A, left panel: average sIPSC (of the indicated number of events) recorded at the two potentials. The change in driving force is expected to reduce the average IPSCs at −13 mV by 78% compared with that recorded at −60 mV. Middle panel: count-matching the number of events recorded at −13 mV with the largest amplitude sIPSCs recorded at −60 mV gives a more accurate value of 72% reduction. Right panel: using the I_mean method gives a similar decrease (84%). B, left panel: average sIPSC recorded under control conditions in a CA1 PC and in another cell in the presence of 200 nm gabazine (SR; averages of the largest 100 events). Middle panel: the phasic current calculated by the I_mean method shows a similar reduction without the need for event detection and count-matching. Right panel: sample all-point histograms measured over 1 s epochs recorded in two different cells in different conditions. Note the decrease in the skewed part of the histogram corresponding to the phasic current when the cell is exposed to gabazine (SR). In A and B, the I_mean was obtained as the average of 60 or 30 1-s segments, respectively.