Voltage-jump analysis reveals that channels with slow kinetics underlie the kainate receptor-mediated EPSC. A, Superimposed currents (bottom) recorded from a cell in response to the superimposed voltage-jump protocol (top). For each trace, a single jump from -60 to -90 mV was applied during the AMPA or kainate receptor-mediated component of the EPSC. B, Charge recovery curve for the fast AMPAR-mediated component to the EPSC. The line is a sigmoidal fit to the data (see Materials and Methods). Inset, Superimposed traces showing the early fast component of the EPSC after subtraction of the capacitance transients illustrating the charge recovery during the AMPAR-mediated EPSC. C, Summary data from all cells (n = 5) for electrotonic index and τ_decay of the synaptic conductance (both derived from the sigmoidal fit to the charge recovery data as in B) and τ_decay of the AMPAR-mediated EPSC_fast as recorded at the soma. D, Charge recovery during the kainate receptor-mediated component of the EPSC for an example cell (charge recovery estimated as the difference between the peak amplitude of the recovered current relative to the slow exponential decay of the kainate receptor-mediated component and normalized to charge recovered at 18 ms). Inset, Example EPSC (capacitance transient subtracted) showing charge recovery for the slow kainate receptor-mediated component at 78 ms after EPSC onset. The line is a biexponential fit to the decay of the EPSC. E, Charge recovery (normalized to recovery at 18 ms) for the kainate receptor-mediated component at 38 and 78 ms after EPSC onset for all cells in which this analysis could be performed (n = 4).