Fig. 6.

Independent of the strength of excitation applied, frequencies of PS bursts from isolated anterior pairs of ganglia (A2 - A3) were as high as or higher than those from isolated posterior pairs (A4 - A5). Pairs of ganglia were isolated by placing TTX blocks on the A1–A2, A3–A4, and A5–A6 connectives (compare Fig. 1). Circles mark the frequencies (mean ± SD) expressed when the two pairs were isolated. Diamonds mark the mean frequencies expressed by these same preparations in the specified concentrations of carbachol before the TTX blocks were imposed.