Figure 2.

Long-lasting depression of Ia IPSPs in lumbar flexor motoneurones following stimulation of extensor nerves

A, the upper two traces show the cord dorsum potential (CDP) and intracellular recording from a PBSt motoneurone (Mn) of a group Ia EPSP evoked by stimulation of the PBSt motor nerve. The lower two traces show the CDP and disynaptic Ia IPSP evoked by stimulation of the antagonist Q motor nerve in the same PBSt motoneurone. Measurements with and without conditioning stimulation of GS (5T, 5 shocks, 200 Hz, conditioning-test interval 37 ms) are shown as dashed and continuous lines, respectively. Each trace is the average of 32 sweeps. B, time course of the changes in the postsynaptic potentials illustrated in A. The abscissa is the interval between the conditioning GS stimulation and the test stimulation of either the PBSt (EPSP, ○) or Q nerve (IPSP, •). The ordinate indicates the size of the conditioned EPSP or IPSP as a percentage of the control EPSP or IPSP. Records were obtained by averaging 32 individual sweeps. Error bars indicate one standard error of the mean.