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Motor Control of Compliant Landings
Does muscle activity in preparation for or during landing change with compliance? To explore whether toads change their muscle activity to produce the difference in joint work I found in my first chapter, I had toads jump onto a compliant platform while recording muscle activity in four muscles that coordinate shoulder flexion (Pectoralis) and abduction (Deltoidius), elbow extension (Anconeus), and wrist extension (Palmaris longus). We discovered that cane toads do not change their muscle activity prior to landing or while landing with their arms, suggesting cane toads adopt the same strategy to stick the landing no matter the surface compliance. |
Above are examples of the same toad hopping on to a rigid surface (left) and a compliant surface (right; 5 mm of displacement per body weight).
The top plots is the limb extension ratio (LER; in purple) throughout landing, where a LER of 1 would be the arms fully stretched out and a value of 0 having the hands flexed up against the chest.
The second through fifth row of plots show the muscle activity of the Deltoidius, Pectoralis, Anconeus, and Palmaris longus muscles, respectively.
The top plots is the limb extension ratio (LER; in purple) throughout landing, where a LER of 1 would be the arms fully stretched out and a value of 0 having the hands flexed up against the chest.
The second through fifth row of plots show the muscle activity of the Deltoidius, Pectoralis, Anconeus, and Palmaris longus muscles, respectively.
Next Step
Finding out that cane toads do not alter their muscle activity regardless of landing compliance suggests the changes in joint work I found in my first chapter are likely not due to the toads actively tuning their muscle activity in preparation for or while landing on a springy surface.
However, one of the major limitations of my work thus far has been keeping the takeoff platform rigid. The toads are always jumping off a rigid surface and may anticipate landing on a similar surface. Just like how you or I may not expect to have a soft landing when jumping off a concrete slab. Click here to learn more about my third chapter which attempts to answer whether cane toads use information from their takeoff to predict what their landing conditions will be.
Finding out that cane toads do not alter their muscle activity regardless of landing compliance suggests the changes in joint work I found in my first chapter are likely not due to the toads actively tuning their muscle activity in preparation for or while landing on a springy surface.
However, one of the major limitations of my work thus far has been keeping the takeoff platform rigid. The toads are always jumping off a rigid surface and may anticipate landing on a similar surface. Just like how you or I may not expect to have a soft landing when jumping off a concrete slab. Click here to learn more about my third chapter which attempts to answer whether cane toads use information from their takeoff to predict what their landing conditions will be.
