(A) Inhibition of spiking in TOR cells was eliminated by only a high concentration of 4-aminopyridine (4-AP, 5 mM, red traces), but not by low concentration (0.1 mM, grey traces). (B) As expected, both low and high concentrations of 4-AP affect AP width and threshold due to blockade of various potassium channels (grey symbols represent individual experiments, black symbols show average results). (C) Representative traces on the left show control and 4-AP-sensitive and insensitive currents from a TOR cell and the graphs show the average voltage dependence of these components (n = 5 TOR cells). Majority (64.2% at −30 mV) of outward currents in TOR cells are sensitive to high, but not to low concentration 4-AP. (D) Firing patterns of TOR and RS cells are not affected by low (0.5 mM, light grey) and high concentrations (10 mM, dark grey) of tetraethylammonium (TEA, n = 9 TOR and n = 13 RS cells). (E) The effect of TEA on AP shape of TOR and RS cells (*: p<0.05, paired sample t-test).