Figure 6.

TEA had no effect on VSI synaptic strength or DSI neuromodulatory effects. A, Effect of TEA on VSI spike shape and synaptic strength. Simultaneously recorded averaged waveforms of five action potentials (top trace) and five corresponding EPSCs in VFN (bottom trace) in control saline and in 5 mm TEA are shown. TEA reduced the magnitude of the VSI spike afterhyperpolarization and caused a slight broadening of the action potential, but it had no effect on the size of VSI-evoked EPSCs in VFN. B, Overlaid traces for VSI-evoked EPSCs in VFN recorded 5 s before the DSI spike train (solid line), 5 s after the DSI spike train (dotted line), and 35 s after the DSI spike train (dashed line) in control saline (left) and in saline containing 5 mm TEA (right). All traces are shown at the same scale. C, TEA had no effect on the DSI-evoked biphasic, bidirectional change in VSI synaptic strength. Averaged data show the sequential effects of DSI stimulation on normalized VSI-evoked EPSCs in control saline (filled circles) and in 5 mm TEA (open squares). Each plot shows a mean value (mean ± SEM) of pooled data obtained from four preparations. The gray vertical bar represents a 5 s DSI spike train. stim, Stimulation.