Activation properties of long-lasting ImGluR(V). A, Voltage-gated calcium currents were suppressed (a) in a solution containing low Ca2+ (0.2 mM), Mn2+ (1 mM), TTX (1 μM), and Cs+ (5 mM). Under this condition (Control), a linear current response was obtained with a depolarizing ramp from −70 mV to −5 mV (Ab, bottom). With the addition of DHPG, an inward ‘sag’ developed in the current response to the same ramp (b). I–V plots (c) were obtained by subtracting the control current response (blue record) from the indicated responses. The I–V plot provided values for the peak amplitude (arrow) and voltage (Vpeak), threshold (Vthr), and reversal potentials (Vrev) of ImGluR(V). B, Plots of ImGluR(V) amplitude (a), and of Vpeak, Vthr, and Vrev (b), for the current (inset) recorded before (i), during (ii), and after (iii) DHPG application in a CA3 pyramidal cell. C, Summary data from 11 CA3 pyramidal cells.