title: A system for the determination of planar force vectors from spontaneously active chicken embryos.
abstract: Generally, a combination of kinematic, electromyographic (EMG), and force measurements are used to understand how an organism generates and controls movement. The chicken embryo has been a very useful model system for understanding the early stages of embryonic motility in vertebrates. Unfortunately, the size and delicate nature of embryos makes studies of motility during embryogenesis very challenging. Both kinematic and EMG recordings have been achieved in embryonic chickens, but two-dimensional force vector recordings have not. Here, we describe a dual-axis system for measuring force generated by the leg of embryonic chickens. The system employs two strain gauges to measure planar forces oriented with the plane of motion of the leg. This system responds to forces according to the principles of Pythagorean geometry, which allows a simple computational program to determine the force vector (magnitude and direction) generated during spontaneous motor activity. The system is able to determine force vectors for forces >0.5 mN accurately and allows for simultaneous kinematic and EMG recordings. This sensitivity is sufficient for force vector measurements encompassing most embryonic leg movements in midstage chicken embryos allowing for a more complete understanding of embryonic motility. Variations on this system are discussed to enable nonideal or alternative sensor arrangements and to allow for translation of this approach to other delicate model systems.
authors.affiliation: Department of Anatomy, Southern Illinois University School of Medicine, Carbondale, Illinois; Center for Integrated Research and Cognitive Neural Science, Southern Illinois University School of Medicine, Carbondale, Illinois; asharp@siumed.edu.
authors.forename: Andrew A
authors.initials: AA
authors.lastname: Sharp
authors.affiliation: Molecular, Cellular and Systemic Physiology Undergraduate Program, Southern Illinois University, Carbondale, Illinois;
authors.forename: Blake W
authors.initials: BW
authors.lastname: Cain
authors.affiliation: Biomedical Engineering Master's Program, Southern Illinois University School of Medicine, Carbondale, Illinois; and.
authors.forename: Joanna
authors.initials: J
authors.lastname: Pakiraih
authors.affiliation: Electrical Engineering Undergraduate Program, Southern Illinois University, Carbondale, Illinois.
authors.forename: James L
authors.initials: JL
authors.lastname: Williams
mesh_terms: D000465:Algorithms; D000818:Animals; D001696:Biomechanical Phenomena; D002642:Chick Embryo; D003627:Data Interpretation, Statistical; D047108:Embryonic Development; D018715:Microscopy, Video / Q000295:instrumentation / Q000379:methods*; D009068:Movement
keywords: 2D; chicken embryo; force vector; kinematics; strain gauge