Fig. 3.

The facilitation of the LTS observed after quinpirole administration persisted after the membrane potential of the cell was adjusted by current injection to the original pre-drug control values. A, A cell recorded during control conditions exhibits an evoked action potential in response to depolarizing current injection (RMP = −66.15). B, Quinpirole administration caused a hyperpolarization of the membrane of this cell by 2.4 mV, in addition to facilitating the expression of the LTS.C, After depolarizing the membrane potential of this cell back to the original pre-drug RMP by current injection, the LTS could still be evoked by small amplitudes of membrane depolarization. It should be noted that LTSs were not evoked at this RMP in the absence of quinpirole administration. mp, Membrane potential.