Figure 7.

Rebound depolarizations in mitral cells are dependent on T-type channels. A, Hyperpolarizing prepulse (4 s) evokes a rebound depolarization in mitral cells. APs are truncated. The rebound was dependent on the size of the hyperpolarizing prepulse. B₁, Inhibition of the T-type channels eliminates the rebound depolarization as indicated by the representative traces (control, black, n = 5; Z941, 10 μm, gray, n = 5). Inset, Large Ca²⁺ influx into the apical tuft of a mitral cell (G/R, upper left, black) accompanied by a subthreshold rebound depolarization (lower left, black). Both are sensitive to Z941 (gray). The jitters on the crest of the control voltage trace are inhibited by Z941 while the trains of APs (lower right, gray) and the train-evoked Ca²⁺ influx into the tuft (upper right, gray) are preserved. B₂, Number of APs (first seconds after the hyperpolarizing prestep) and low-threshold-evoked oscillations significantly decreased in the presence of Z941. *p < 0.05. **p < 0.01.