Ipsilateral two-CPG models. Two ipsilateral two-CPG models were tested: 1) ipsilateral flexor-flexor/extensor-extensor (f-f/e-e) and 2) ipsilateral flexor-extensor/extensor-flexor (f-e/e-f). Representative time series output bursts for the two-CPG model with either excitatory or inhibitory sensory feedback which produced maximal enhancement. Solid lines are flexor bursts and dotted lines are extensor bursts. * indicate the upper limb bursts (gray line) are out-of-phase with the lower limb bursts (black lines). Enhancement amplitudes are shown as percentages of the baseline amplitude of 0.96. "Max" label indicates maximal enhancement. 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, 1, 2, 3 and 4. Ipsilateral coupling gain values tested were -2 to 1 in increments of 0.25. The helical symbol represents a muscle spindle that signifies sensory feedback.