Meeting Abstract
A controlled landing requires preparation. In midair, cane toads (Bufo marinus) activate muscles to initiate movements that position their forelimbs appropriately at the point of impact to absorb and dissipate energy during landing. These preparatory actions vary depending on the hop conditions. For example, longer hops lead to a more extended forelimb configuration at impact, and hops in which an animal rolls to one side after takeoff lead to asymmetrical patterns of forelimb movement and muscle activity. The ability of anurans to vary landing preparation with impact conditions appears to require the integration of sensory feedback, yet little is known about the necessity or prioritization of various sensory modalities for coordinated landing in hopping anurans. Here we present several experiments in which feedback from visual, vestibular and proprioceptive systems were conflicted or ablated. We found that landing preparation was altered if any sensory system was compromised. In visually impaired animals, subtle changes in the timing and magnitude of forelimb preparatory movements were observed, and the same was true of animals lacking hind limb proprioceptive feedback during takeoff. Nevertheless, in both conditions the ability to coordinate landing was preserved. In contrast, landing coordination was totally disrupted by the absence of vestibular information as a result of unusual takeoff angles and abnormal forelimb and hind limb movements following takeoff. Our most intriguing results from experiments conflicting sensory signals showed that toads appear to prioritize different modes of sensory feedback depending on hopping conditions and that, unlike mammals, cane toads may rely most heavily on non-visual feedback to coordinate landing.
