Fig. 11.

Intersegmental phase differences between the HE(8) and HE(12) motor neurons and between constriction of the corresponding hearts positively correlate in the peristaltic mode in vivo (solid line: regression line; P ≤ 0.015) (A) but do not correlate in the synchronous coordination mode (B). The (dashed) identity line represents equal phase differences between the 2 motor neurons and the 2 hearts. Note that, across preparations, in the synchronous mode the phase differences between the constrictions of the 2 hearts vary more than those between the bursts of the motor neurons. Note also that in 7 of the 9 preparations in the peristaltic mode the phase differences between the 2 heart segments exceed those of the heart motor neurons. Each symbol represents the mean ± SD of the phase differences for several beat cycles (see methods).