Figure 2.

Mixed inputs to an L4 lamina I neuron. Mixed (monosynaptic and polysynaptic) EPSCs were elicited in an L4 lamina I neuron by stimulating L1–L6 roots. A, Each root was stimulated at least 10 times with a 1 ms current pulse at 0.1 Hz to elicit both Aδ- and C-fiber mixed EPSCs. For each root, individual recordings (upper traces) were averaged (lower traces). B, Each dorsal root was stimulated at least 10 times with a 50 μs pulse at 1 Hz to elicit only Aδ-fiber mixed EPSCs. Averaged responses (lower traces) were obtained from individual recordings (upper traces). C, The averaged traces are shown superimposed. Holding potential was −70 mV. Here and in the following figures, the fastest evoked EPSCs (monosynaptic and polysynaptic) appeared with latencies corresponding to afferent conduction velocity below 4.4 m/s (conduction velocity of the fastest Aδ-afferents in dorsal roots, Pinto et al., 2008a). Note that all roots differed in length, and therefore, had different latency criteria for separation of Aδ- and C-fiber EPSCs.