One-CPG model. Each symbol represents the frequency and peak amplitude of individual bursts from a single Matsuoka oscillator for different combinations of sensory feedback gains (ks) and frequencies (kωs). The equations for the Matsuoka oscillator indicate that negative sensory feedback gains are excitatory and positive sensory feedback gains are inhibitory. Enhancement refers to burst amplitudes greater than the baseline condition of no sensory feedback, hs = 0. Enhancement amplitudes are shown as percentages of the baseline amplitude of 0.96. Grid intersections indicate parameter combinations tested. Intersections without a symbol indicate that the output behaviour did not reach steady state or did not have alternating flexor and extensor bursts. Sensory feedback gain values tested were 0, 0.1, 0.5, 1, 2, 3, 4, and 5 while sensory feedback frequency gain values tested were 0, 0.5, 1, 2, and 3.