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Takeoff Conditions May Inform Landing Conditions
Do cane toads predict landing conditions from their experience during takeoff? I developed an experimental procedure disrupted the toad's ability to sense its leg muscles so they would not be able to feel if they were jumping off a rigid or springy surface, and may not coordinate their arms correctly to land. I found toads extended their elbows slower after recovery but still landed effectively, suggesting the importance of sensory information from the legs informing landing behavior in the arms. If you want to learn more about this project after watching the video to the left check out my dissertation recording where I go more in-depth as well as my other research videos. |
Methods
The diagram to the right illustrates the three conditions where I tested the toad's jumping performance. The first (left-most) are the in-tact toads prior to any surgery. The middle is following sham surgery where the nerve is still in-tact and functional. Finally (right-most) is 6 months following nerve transection surgery. |
Results
The above visualizations depict raincloud plots for three variables of interest. Here the cloud (bell-shaped curve) represents the distribution of all jumps I recorded. The larger, central dot represents the mean or average value after accounting for individual variation with error bars showing the 95% CI of the mean. All the rain drops to the right of each distribution convey each jump trial recorded from the toads. Lowercase letters above distributions that differ signify significant differences in the mean between the conditions.
A) The average rate of leg extension during takeoff (units of leg lengths per second) did not significantly differ between any of the surgical conditions suggesting we did not alter the leg behavior during takeoff. This is helpful because we don't want to disrupt the legs, but want to see if sensory info from the legs is useful for coordinating the arms.
B) Here we saw the average rate of elbow extension (units of degrees per milliseconds) was significantly reduced following both surgeries. It seems cutting the sciatic nerve does slow down their arm extension. While we saw a similar trend in the sham individuals this data should be taken with a grain of salt since we only had a group size of N = 4 and this group did jump significantly farther on average than the pre-surgery and post-surgery individuals.
C) I compared the muscle activity of the anconeus (elbow extensor similar to our triceps muscle) after surgery to normal, pre-surgery toads from other studies and found they only have their muscle on for about half the normal amount of time. This may help to explain why the elbow extends more slowly (see plot B) because the muscle extending the elbow is on for a shorter period.
The above visualizations depict raincloud plots for three variables of interest. Here the cloud (bell-shaped curve) represents the distribution of all jumps I recorded. The larger, central dot represents the mean or average value after accounting for individual variation with error bars showing the 95% CI of the mean. All the rain drops to the right of each distribution convey each jump trial recorded from the toads. Lowercase letters above distributions that differ signify significant differences in the mean between the conditions.
A) The average rate of leg extension during takeoff (units of leg lengths per second) did not significantly differ between any of the surgical conditions suggesting we did not alter the leg behavior during takeoff. This is helpful because we don't want to disrupt the legs, but want to see if sensory info from the legs is useful for coordinating the arms.
B) Here we saw the average rate of elbow extension (units of degrees per milliseconds) was significantly reduced following both surgeries. It seems cutting the sciatic nerve does slow down their arm extension. While we saw a similar trend in the sham individuals this data should be taken with a grain of salt since we only had a group size of N = 4 and this group did jump significantly farther on average than the pre-surgery and post-surgery individuals.
C) I compared the muscle activity of the anconeus (elbow extensor similar to our triceps muscle) after surgery to normal, pre-surgery toads from other studies and found they only have their muscle on for about half the normal amount of time. This may help to explain why the elbow extends more slowly (see plot B) because the muscle extending the elbow is on for a shorter period.
Next Step
If you are interested in learning more about my work you can check out my dissertation defense recording or read the peer-reviewed journal article where I discuss my findings in greater detail.
You can also peruse my first project on how cane toads coordinate landing on surfaces of varying compliance and my second project which focused on whether cane toads modulate muscle activity to stick the landing on springy surfaces, if you haven't already.
If you are interested in learning more about my work you can check out my dissertation defense recording or read the peer-reviewed journal article where I discuss my findings in greater detail.
You can also peruse my first project on how cane toads coordinate landing on surfaces of varying compliance and my second project which focused on whether cane toads modulate muscle activity to stick the landing on springy surfaces, if you haven't already.
References
Cox, S.M. and Gillis, G.B. (2020). The integration of sensory feedback in the modulation of anuran landing preparation. J. Exp. Biol. 223(3). https://doi.org/10.1242/jeb.214908
Cox, S.M., Ekstrom, L.J., and Gillis, G.B. (2018). The influence of visual, vestibular, and hindlimb proprioceptive ablations on landing preparation in cane toads. Integr. Comp. Biol. 58(5), 894-905. https://doi.org/10.1093/icb/icy059
Duman, A., & Azizi, E. (2023). Hindlimb muscle spindles inform preparatory forelimb coordination prior to landing in toads. Journal of Experimental Biology, 226(2), jeb244629. https://doi.org/10.1242/jeb.244629
Cox, S.M. and Gillis, G.B. (2020). The integration of sensory feedback in the modulation of anuran landing preparation. J. Exp. Biol. 223(3). https://doi.org/10.1242/jeb.214908
Cox, S.M., Ekstrom, L.J., and Gillis, G.B. (2018). The influence of visual, vestibular, and hindlimb proprioceptive ablations on landing preparation in cane toads. Integr. Comp. Biol. 58(5), 894-905. https://doi.org/10.1093/icb/icy059
Duman, A., & Azizi, E. (2023). Hindlimb muscle spindles inform preparatory forelimb coordination prior to landing in toads. Journal of Experimental Biology, 226(2), jeb244629. https://doi.org/10.1242/jeb.244629