Fig. 7. Mechanical stimulation of the ovotestis induces an efferent reflex response from the CNS that travels into both the pericardial (PC) and ovotestis branches of the intestinal nerve. (A) Traces recorded at four positions on the intestinal nerve (see Fig. 1). Action potentials conducted to and from the ovotestis were recorded by two electrodes (SV-P and SV-D) placed on the nerve as it passes over the seminal vesicle; afferent vs efferent spikes were discriminated using timing differences at these two electrodes. The arrowhead indicates stimulation of the ovotestis with a wooden applicator stick (3 s duration). Note that an elevated level of activity is recorded at all electrodes in the 10 min period following the stimulus. (B) Raster plot showing the timing of afferent and efferent spikes recorded at seminal vesicle electrodes as well as efferent activity recorded at the pericardial electrode. Time 0 indicates the onset of tactile stimulation.