Figure 7.

Effect of conditioning GS stimulation on the amplitude of unitary IPSP and membrane potential in a PBSt motoneurone

A, average of the membrane potential in a PBSt motoneurone, triggered by the glutamate-induced activity in a Q-coupled Ia inhibitory interneurone, The upper trace shows the extracellular spike of a single Ia inhibitory interneurone, which was used to trigger the averager. The lower trace shows the unitary IPSP (U-IPSP) evoked by the spike activity. B, time course of the peak amplitude of the U-IPSP following the conditioning GS stimulation (5T; 200 Hz) applied at time 0. Insets illustrate U-IPSPs at -100, 20 and 100 ms from the conditioning stimulation. Each average involved at least 30 spikes. Voltage calibration refers to intracellular recordings only. **P < 0.001 compared with control. C, intracellular recording from the PBSt motoneurone showing that the conditioning GS stimulation induced an IPSP in the motoneurone.