Figure 3.

Effect of T-Type calcium channel blocker nickel chloride (NiCl₂) on cholinergic gamma oscillations in the rat hippocampus. (A) Original traces (left) and power spectrum (right) of hippocampal gamma oscillations before (black) and after (orange) application of NiCl₂ (0.5 mM). Local field potential traces were lowpass filtered at 200 Hz and bandstop filtered at 50 Hz. (B) Normalized power of cholinergically induced gamma oscillations after bath application of NiCl₂ compared to control. Control (blue): n = 13 slices, N = 9 animals; NiCl₂ 0.1 mM (purple): n = 7, N = 3, p = 0.002; 0.5 mM (orange): n = 11, N = 4, p < 0.001. (C) Normalized frequency after application of NiCl₂ compared to control. NiCl₂0.1 mM (purple): p = 0.406; 0.5 mM (orange): p = 0.088. (D) Normalized power before, during and after bath application (gray) of different concentrations of NiCl₂ (0.1 mM, purple; 0.5 mM orange) compared to control (blue). (E) Low voltage- and high voltage-activated calcium currents recorded by a first depolarizing step from −80 to −40 mV and a second step from −40 to −10 mV, respectively, of the same cell before (blue) and after (orange) bath application of NiCl₂ (0.5 mM). (F) Amplitudes of low and high voltage-activated calcium currents evoked by the first and second step, respectively, before and after application of NiCl₂ (0.5 mM). First step: p < 0.001. Second step: p = 0.331; n = 7, N = 4, paired t-test. (G) Step protocol (above) and original traces of calcium currents (below) with voltage steps from −70 mV to +20 mV and holding potential of −80 mV before (blue) and after (orange) bath application of NiCl₂ (0.5 mM). (H) Amplitudes of calcium currents evoked by depolarizing steps as described in (G). For LFP experiments recording temperature was between 34 and 36°C. Patch-clamp experiments were carried out at room temperature (22–24°C). Data shown as mean ± SEM. **p < 0.01, ***p < 0.001. ACh, acetylcholine; Phys, physostigmine.