Vision's role in the ability of cane toads to absorb landing forces.
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In order to stick a landing, the propulsive forces and acceleration experienced during take off must be completely dissipated as the body completely decelerates. The cane toad (Bufo marinus) is an ideal model for looking at joint kinematics along with coordination upon landing, due to the fact that they control their entire landing using only their fore limbs. Since hopping is the main form of locomotion for anurans, they are frequently using this motor control in order to put together successive hops. Failure to prepare for and dissipate the large landing forces could seriously injure the toad. This study focuses o two main objectives. The first objective is to determine the normal landing force profile of the cane toad. This profile will act as the baseline for the second objective, which is to determine the role of vision in force dissipation during level hops. Both of these objectives were examined using hop experiments along with a three-dimensional force plate to collect the force profiles. I looked at both forelimb and hind limb kinematics during the landing process, along with the anticipatory muscle recruitment used by anurans to determine the motor patterns of each of the six toads used. The optic nerve of each toad was severed in order to test the necessity of vision in the ability to safely land while remaining balanced. Without vision the toads were still able to successfully control the anticipatory tuning of their muscles. Along with muscle recruitment, learning and feedback during takeoff from other sensory systems, including the vestibular and proprioceptive systems, were enough to compensate for the loss in vision.
Description:Thesis--Departmental honors in Neuroscience.MIME type:application/pdfFile Size:581.4Kb