Figure 6.
The ionic basis of the rebound burst. In all panels, control traces are drawn as thinner lines. CsCl (3 mm), which blocks the hyperpolarization-activated cationic current Ih, blocked both the sag and the rebound depolarization in X94 and GIN cells (A, B, open arrowheads). In bursting X98 cells, CsCl blocked the sag (C, open arrowhead) but not the burst (filled arrowhead). In contrast, the IT channel blocker mibefradil (10 μm) did not block the sag (D, open arrowhead), but blocked the burst despite the large depolarizing rebound (filled arrowhead) evoked by a stronger hyperpolarization (−120 pA in mibefradil, compared with −40 pA in control). Note that in A–C, the superimposed responses in each panel were evoked by the same current step. Calibration: 40 mV, 200 ms.