Figure 2.

Ionic mechanisms of the fast subthreshold membrane potential oscillation in thalamocortical cells. (A) TTX did not block oscillation, but increased voltage threshold (Insets, autocorrelograms). (B) Plot of voltage responses to outward and inward current pulses from −60 mV, before and after TTX. Following TTX, the effective depolarization decreased (Inset) and a strong outward rectification for membrane potentials positive to −50 mV became evident. (C) NaCl equimolar substitution with choline chloride did not block oscillation. (D) CdCl₂ (up to 0.2 mM) blocked the fast subthreshold membrane potential oscillations but not the low-threshold spikes (arrows). (E) Fast subthreshold oscillations became more evident after equimolar replacement of CaCl₂ by BaCl₂.