Inhibition of T-type Ca²⁺ channels decreases the strength of mitral–mitral cell connections. A₁, Mitral cell pairs were visualized by Alexa-594. Representative experiment shows an example presynaptic stimulation in M₁ at V_rest (20 Hz; top) and the averages of evoked EPSPs in M₂ at V_rest in the absence (control, black) and presence of Z941 (10 μm, gray). Inset, Overlaid averages of EPSP2. A₂, Individual EPSP1 traces are shown after baseline subtraction. Arrows indicate the peak of average EPSP1 under control conditions and in the presence of Z941. B₁, EPSPs were recorded in cohorts of five sweeps in control (black, n = 5) and in the presence of Z941 (gray, n = 5, 5–15 min bath application). Distances between the dots do not represent exact time, only the sequence of recordings. B₂, EPSP amplitudes (thin lines, left) and PPRs (thin lines, right) are shown in control and in the presence of Z941. Black dots connected with thick black lines indicate the means of five individual experiments. **p < 0.01.