Figure 5.

I_h gradient persists in more mature animals (P22). (A) Pharmacologically isolated I_h current traces were elicited by depolarizing and hyperpolarizing voltage steps from −60.5 mV to potentials between −40.5 mV and −120.5 mV (5 mV step increment). Current traces are representative for the dorsal and the ventral part of the MSO. (B) I-V relationships of steady-state I_h density for ventral (n = 8) and dorsal (n = 10) neurons emphasize that I_h density amplitudes are smallest in dorsal neurons and largest in ventral neurons (B1). I_h density amplitudes for a voltage step to −110.5 mV (B2). (C) The weighted activation time constants are voltage dependent and largest in the dorsal part of the MSO. (D) The voltage-dependence of I_h activation was measured from the tail current. In dorsal neurons the I_h activation curve is shifted to more negative voltages (D1). Half-maximal activation voltage was measured in each experiment and averaged (D2). Black symbols: dorsal neurons; white symbols: ventral neurons. ^*P < 0.05, two-tailed unpaired t-test.