Figure 5.

B6, B9, and B3 generate little force in most bites and in some swallows. A–C, Contour plots of forces generated by individual neurons B6, B9, and B3 activated at different durations (i.e., 0.5–5 s in increments of 0.5 s) and frequencies (i.e., 5–15 Hz in increments of 5 Hz) in the absence of neuromodulation from the MCCs by bathing the buccal and cerebral ganglia in a high-divalent cation solution (3× Mg²⁺, 3× Ca²⁺). Normalized forces (see Results) were plotted against the corresponding durations and frequencies. The thick white line represents a minimal force level that is 0.005 times the maximum normalized force in each plot (see the label above each plot). Black lines represent 0.2, 0.4, 0.6, 0.8, and 1.0 times the maximum normalized force in each plot (see the labels above each contour region). Dots represent the duration and frequency levels of B6 or B9 neural activity (from the suspended buccal mass) or B3 neural activity (in vivo) in biting responses (pink dots) or swallowing responses (white dots). The large pink dot at (0, 0) in B represents seven biting responses of B9 obtained in the suspended buccal mass preparation. The large pink/white dot at (0, 0) in C represents 135 bites and 46 swallows of B3 obtained in vivo. Percentage values shown in A–C indicate how many points fall outside the thick white line in biting (pink number) and swallowing (white number), i.e., correspond to forces <0.005 times the maximum possible.