Figure 6.

Contralateral control of the ipsilateral monosynaptic input. A, Recording of the cDRPs. Left panel shows a schematic of how the cDRPs were recorded in the isolated spinal cord preparation. The recording electrode was placed on the contralateral L5 dorsal root close to where it entered the spinal cord. Middle, cDRPs evoked by stimulating Aβδ-afferents (Aβδ-cDRP), C-afferents (C-cDRP), and Aβδ/C-afferents (Aβδ/C-cDRP). Right, Bicuculline (20 μm) effect on the Aβδ-cDRP and Aβδ/C-cDRP. B, Contralateral Aβδ-range conditioning abolished ipsilateral Aδ-EPSC component. Schematic, Contralateral Aβδ-afferent induces presynaptic inhibition of the ipsilateral Aδ-fiber input to a Lamina I neuron. C, Contralateral Aβδ-conditioning attenuated the ipsilateral Aδ-EPSC and abolished the low-threshold-(LT)-C-EPSC. Schematic, a contralateral Aβδ-afferent induces inhibition of the ipsilateral Aδ- and LT-C-afferents. In B, C, 50-µs stimuli were applied to activate Aβδ-afferents or LT-C-afferents. Monosynaptic EPSCs are indicated by filled arrowheads. Holding potential, −80 mV. The time moments when conditioning (contralateral) and test (ipsilateral) stimuli were applied are indicated by red and blue arrows, respectively. For each type of response, five individual traces are shown with the average of 10–15 traces. Averaged responses to the test stimuli are shown superimposed below. Location of an inhibitory interneuron (In) is not known.