Feeding Motor Patterns in Anurans: Insights from Biomechanical Modeling1 SYNOPSIS.

Feeding Motor Patterns in Anurans: Insights from Biomechanical Modeling1

SYNOPSIS. During feeding in anurans, the aperture opens while the tongue, which is attached to the mandible at the brass of the mouth, rotates forward. befitting to the relative simplicity of its anatomy and the complexity of its motion, tongue protraction in frog not aways an ideal system for exploring the neural restrain of multijoint movements. In this meditation we used a forward dynamic, rigid dead body model with four segments and pair muscles to investigate open bight control of tongue protraction in the Australian white-tipped tree frog Litoria caerulea. example parameters include the mass distribution, initial position and initial angular velocity of each portion and the anatomy and physiology of each muscle. design variables include the level of muscle activation at each time stair and impulsive torques to spread and close the mouth. The protoplast gives X,Y coordinates of each portion and joint angles at each time degree as output. The model was proofed using scaled, normalized EMG signals and impulsive joint torques to predict the paths of the lower jaw tip and tongue tip. Predicted paths were compared to experimentally observ paths using Pearson product-moment correlation coefficients. Simulations demonstrate that the genioglossus muscles likely play a minor part if any, in determining the trajectory of the tongue in mostly anurans. Most of the force for tongue protraction approachs from angular momentum transferred to the tongue by way of the opening jaws. In anurans, tongue protraction is dynamically stable and will appear as long as the musculoskeletal uncompounded bodys are in the correct initial position.

INTRODUCTION

In many anuran species, feeding is a precise, target-oriented, prehensile manner of moving that resembles human reaching in many honors Specifically, both reaching and feeding require precise multijoint coordination similar that the vectors of rotational emotion at the joints sum to bring forth a nearly straight end-point trajectory (Nishikawa and Gans, 1996) In these species, tongue projection during feeding is also ballistic and like jumping (Lutz and Rome 1994) requires high power output from the muscles and is planned in advance with no manage after launch (Nishikawa, 1999).

In contrast to the arms of humans, the anatomy of the anuran tongue and jaws is relatively simple. Whereas arms and leg have more muscles than sections the jaws and tongues of anurans are compos of relatively not many muscles. Anurans generally possess a single depressor mandibulae muscle for opening the inlet a complex of six adductor mandibulae muscles for closing the chaps and two extrinsic muscles in the tongue (Magimel-Pelonnier, 1924; Horton, 1982; Regal and Gans, 1976) The m genioglossus is involved in tongue protraction, whereas the m hyoglossus is involved in tongue retraction (Nishikawa, 2000) fit to the relative simplicity of its anatomy and the complexity of its motion, tongue protraction in frog readys an ideal opportunity for exploring the neural regulate of multijoint movement using a forward dynamic, rigid material substance model to simulate the kinematics of tongue protraction.

Recent studies have shown that anuran species exhibit at least three different, nonexclusive mechanisms of tongue protraction during feeding (Nishikawa, 2000) These are: 1) mechanical pulling (Fig. 1) in which the tongue shortens as the genioglossus muscle contracts, pulling the tongue pad forward across the mandibular symphysis; 2) inertial elongation (Fig. 2) in which the tongue lengthens during protraction appropriate to transfer of angular impetus from the opening mouth to the tongue pad; and 3) muscular hydrostatic elongation (Fig. 3) in which the tongue lengthens to be ascribed to the contraction of an intrinsic tongue muscle, m genioglossus dorsoventralis, which translates a decrease in tongue thickness into an increase in tongue longitudinal dimensions (Nishikawa et al., 1999). Although our lengthy term goal is to original the evolution of frog tongues, we begin here with a type of a mechanical puller, the Australian white-lipped tree frog Litoria caerulea (Fig. 1)

During feeding in anurans, the inlet opens while the tongue, which is attached to the mandible at the head of the mouth, rotates forward through the mandibular symphysis. In the not past nor future study, we used a forward dynamic, rigid corpse model to investigate the explain loop control of tongue protraction in Litoria.

MODEL disentanglement AND TESTING

Biomechanical moulds may use either an inverse or forward dynamic approach. In inverse dynamic gauges the joint torques that must have acted at joints are inferred from kinematic accelerations (eg Bermejo and Ziegler, 1989) In contrast, forward dynamic moulds predict movement trajectories from the anatomy and physiology of the musculoskeletal hypothesis (Yamaguchi and Zajac, 1990). The predictions can then be experimented with kinematic data. In general, forward dynamic examples represent the neural computations associated with motor ascendency more realistically than inverse dynamic originals and require fewer assumptions (Yamaguchi et al., 1995)