A, the prolongation of OCP-induced hyperpolarizations (displayed at an expanded time scale in a and b) by 1-EBIO (200 μm) was accompanied by a prolongation of silent periods. B, elevation of the frequency of OCP-induced hyperpolarizations (displayed at expanded time scale in a and b) by caffeine (1 mm) in 1-EBIO was accompanied by a prolongation of silent periods. Inset shows the cumulative histogram of interspike intervals for three cells. The histogram in caffeine is characterized by an increase in long interspike intervals. Average and standard errors (dashed lines) of data falling into a bin size of 10 ms (total number of intervals in 1-EBIO and 1-EBIO + caffeine, respectively: 61 and 125) were plotted. C, during the transient increase in the frequency of OCP-induced hyperpolarizations upon application of CPA (10 μm) in 1-EBIO, spike discharge ceased. Discharge restarted together with the later blockade of OCPs. OCP-induced hyperpolarizations and their deletion are displayed at higher time resolution in a, b and c.