George Varick Lauder - US grants

The overall goal of this proposal is to investigate the extent to which patterns of muscle function in animals can be modified. Key general questions addressed by this research include the following. (1) To what extent do patterns of muscle function change during development, and what causes the changes that are found to occur? (2) To what extent do patterns of muscle function differ among both closely related and distantly related species of animals? (3) How dependent are patterns of muscle function on the environment that animals are found in? These questions will be studied using quantitative techniques to measure muscle function and statistically test for differences among species, among developmental stages, and among experimental treatments. The skull musculature in salamanders and turtles is used as an experimental system to investigate these questions. These organisms were chosen because they allow comparisons of muscle function in different environments and muscle function can be studied throughout development. This research will contribute to our understanding of he biomechanics of muscle work in vertebrates the physiology of complex movement sequences and the evolution of feeding behavior in lower vertebrates.

Funds are requested for the purchase of a high-speed video system for motion analysis. This equipment would be used to study the physiology of the musculoskeletal system in vertebrates and invertebrates. Research questions to be addressed with this equipment include: (1) What factors regulate variation in motor output to skeletal muscle during normal behavior? (2) What is the effect of temperature on skeletal muscle performance? (3) How efficient are muscles, and how much work do they do during movement? Current imaging techniques for the study of musculoskeletal function (primarily conventional video and filming) do not provide adequate capabilities for the study of complex movements in three dimensions, the superposition of analog data on the movement image, or digital image manipulation and analysis.

We presently lack a broad comparative understanding of the neuromuscular basis of lower vertebrate locomotor behavior. Notably, no previous study has quantitatively measured axial muscle activity in salamanders which are the most primitive extant tetrapodal vertebrates. The proposed research on fish and salamander locomotor behavior will simultaneously examine axial movements and the underlying patterns of muscle activity (the motor pattern). By comparing taxa with different shapes, numbers of body segments and limbed versus limbless animals, the influence of morphology on motor pattern will be assessed. By altering viscosity and determining the motor pattern for terrestrial and aquatic locomotion, the influence of the environment on the motor pattern will be determined. Comparisons of axial motor patterns over a wide range of speeds, taxa, and environmental conditions will allow examination of the plasticity of neural control in locomotor behaviors.

Evolutionary studies often conclude that lineages of organisms have acquired "adaptations" -- novel morphological, behavioral, ecological, or reproductive features that confer some advantage to individual organisms. Very rarely do these studies confirm the actual advantage by direct measurement. One example is the evolution of the symmetrical ("homocercal") fish tail from asymmetric ("heterocercal") precursors. The conclusion has been that the homocercal tail conferred higher speed, greater maneuverability, and faster acceleration. Dr. George Lauder proposes to use newly developed micro-accelerometers, mounted on the tails of fish swimming in flow tanks, to gather performance data to test this conclusion. The accelerometer data gathering will be coordinated with Dr. Lauder's high-speed video imaging and electromyography (muscle activity) monitoring systems. The first performance data will emerge for homocercal and heterocercal fishes. The proposed research is inherently risky, being the first application of new sensors to a biological problem. Extensive software development will be necessary to couple the three data streams. If this Small Grant for Exploratory Research Project is successful, biologists will have acquired a powerful new technique for assessing functional capabilities, and a significant question in fish evolution will have been addressed.

The proposed research will study how muscle function and bone movement (physiological features of organisms) correlate with structural (morphological) and behavioral features. Most work to date has focused on animal morphology, and relatively little research has been done on the physiological function of features of organisms as these functions relate to morphology and behavior. In particular, a general question of interest to comparative biologists will be addressed: how congruent are the distributions of physiological and morphological characteristics in organisms? The muscles and bones of the head region in fishes will be used as a model system to investigate this question. With nearly 23,000 species, ray-finned fishes comprise more than half of all vertebrates, and have proven to be an excellent model system for the study of animal function in the past. In addition, many of the fish groups to be studied are of considerable economic importance while others occur in regions of the world where there is great concern for the loss of biodiversity. This research will contribute to our understanding of (1) the utility of physiological data for testing comparative hypotheses in biology, (2) the biomechanics of bone and muscle function in vertebrates, and (3) our understanding of the biodiversity of the largest group of vertebrates.

9501332 Cappo In this Small Business Innovation Research Phase II project, Learning in Motion is developing a collection of assessment items to support mathematics instruction in grades K-2 that is aligned with the NCTM Standards. The collection of items was begun in 1994 and is being evaluated and augmented with additional items with the cooperation of Thomas A. Romberg of the University of Wisconsin and Jan de Lange of the Freudenthal Institute in the Netherlands. Scoring rubrics are being developed and the items and rubrics are being tested in schools. a Teacher enhancement component is being designed to help teachers build their own expertise in the area of assessment. The collection of assessment items is being made available for Macintosh and Windows environments and the accompanying software allows teachers to search for items using a variety of criteria, including level of difficulty, grade level, content strand, role of context, and length of time for completion. This project will create an assessment tool offering dynamic reporting thus giving teachers the direction they need to make important curriculum and testing decisions at the classroom level. Teachers will be able to assess their students' understanding of mathematics at higher levels and to build better assessment programs overall.

9623627 Lauder Natural selection is believed to maintain symmetry in vertebrate jaws because any deviation from symmetry would negatively affect the ability to acquire food. Yet, as adults, flatfish have morphologically asymmetrical jaws and might exhibit asymmetrical prey capture. This project will determine if and how functional asymmetry is produced in two flatfish species using high-speed video analysis, morphological description, electromyography, and three- dimensional modeling of jaw mechanisms. Preliminary results indicate that one flatfish species produces asymmetrical gape and bending of the jaws out of the midline during prey capture. However, another species does not experience jaw bending or asymmetrical gape. This project will focus on modifying current two-dimensional models to produce three- dimensional models which can accurately predict functional asymmetry. Models generated will be used in the future to predict prey capture behavior in other flatfishes and applied to symmetrical fishes to gain a better understanding of the three-dimensional nature of prey capture mechanisms. This project will add to our understanding of morphological diversity, and related diversity in the capture of prey, that can exist in an important group of organisms.

Lauder 9807012 The study of how animals move and generate force against the environment has been a topic of interest to biologists for hundreds of years. One key reason for this interest is that it is very difficult to understand how muscles and bones function to cause movement unless one is able to measure the effect of muscle contraction. This appears as force exerted on the environment. However, despite the importance of the ability to measure forces, analysis of the effect of muscle contraction has remained inferential for many moving organisms because of our inability to directly measure force when animals move in air or water. On land, animals exert force on the ground and these forces can be measured directly. But such direct measurements are not possible in fluids, and biologists have lacked a means of making such measurements. This proposal will apply the results of a technique developed recently by engineers called Digital Particle Image Velocimetry (DPIV) which allows direct quantification of flow in moving fluids and the calculation of the force exerted on the fluid by organisms. This technique will be applied to a classical problem in vertebrate biology: the function and evolution of fins in fishes. Because of the prominence of median fins in early vertebrate fossils, their importance in locomotion, and the diversity of median fin shapes in fishes, the evolution of fins has been discussed in virtually every textbook of comparative anatomy, paleontology, and functional morphology. This study will use DPIV to visualize directly water velocity over fins of fishes and to calculate the forces that result from movement. The PI will use DPIV in conjunction with analysis of three-dimensional fin movements and recordings of the electrical activity generated by fin muscles to test hypotheses about how fishes generate force on the water. Preliminary data for this study are presented which demonstrate feasibility of applying this technique and init ial results show the character of the data that would result from this research. This proposal will introduce a powerful new technique for the experimental study of aquatic locomotion, and by directly quantifying for the first time flow around and behind fins, this study will provide novel data on mechanisms of aquatic propulsion and contribute to clarifying a classic issue in vertebrate functional morphology.

A hallmark of the enormous diversity of vertebrate animals is extensive variation in the structure and function of the pectoral appendage, which is fin-like in fishes and forms the upper limb in land vertebrates. How does this key feature of vertebrate design function, and what have been the major evolutionary pathways that lead to the forelimb that characterizes mammals? This proposal is designed to address these questions by directly measuring the function of pectoral appendages in water. Although pectoral function has been the subject of speculation for over 100 years, and nearly every textbook in comparative anatomy and paleontology discusses hypotheses of pectoral function, the difficulty of quantifying the effect of pectoral motion in water has prevented any direct experimental tests of these ideas. This grant will apply a novel engineering technique (Digital Particle Image Velocimetry) which allows the reconstruction of three dimensional flow patterns and direct measurement of the force that limbs exert on the water. For the first time we can quantify the function of structures working in fluids, and test long-standing hypotheses about how animals control their movement in water.

This research will demonstrate the utility of applying novel engineering approaches to the study of vertebrate structure and function. The planned experiments will test old hypotheses and generate new ideas on which to base interpretations of evolutionary and functional patterns in the vertebrate forelimb.

A grant has been awarded to Harvard University under the direction of Dr. George Lauder for the acquisition of a volumetric imaging system for the three-dimensional reconstruction of macroscopic fluid flows in organismic biology. The instrumentation will be shared among three cooperating institutions (Harvard, Brown University, and the University of Rhode Island) to: (1) analyze air flow patterns resulting from wing and body movements of flying bats and birds, (2) study water flow patterns in the wake of swimming fishes, (3) analyze water flow patterns during prey capture by small sharks, (4) study air flow over leaves and flowers of plants, and (5) measure unsteady pressure or shear-driven flows adjacent to flexible boundaries. The study of air and water flow patterns resulting from animal locomotion and prey capture is a major endeavor in the field of biomechanics. As animals capture prey and move through air and water, they generate complex three-dimensional patterns of fluid movement that reflect the application of force to the environment. Understanding these patterns of fluid movement is critical to uncovering the fluid dynamic mechanisms that govern flight, swimming, and the capture of prey by organisms living in fluids. Similarly, understanding the process of wind pollination in plants and the movement of air over leaves is dependent on quantification of air flow and measurement of air velocities around complex three-dimensional plant structures.

The instrumentation will benefit directly numerous graduate students currently in the laboratories of the major and minor user faculty by providing them with the latest technology for the study of biological fluid mechanics. Three of the major users teach advanced undergraduate research project classes in biomechanics (at two different institutions), and undergraduates doing projects in the area of biological fluid mechanics will have the opportunity to use this equipment as they participate in laboratory research projects.

Organisms that live in the water represent a substantial fraction of life's diversity, and understanding how animals move through water, exert forces on their environment, and control their body position in a turbulent environment is critical to developing insights into the diversity of aquatic life. However, attempts to study this question over the past 20 years have met with many difficulties. Chief among these has been the considerable technical difficulty of quantifying the forces exerted by the movement of organisms on the water. On land such measurements are technically easy (stepping on a scale, for example, gives a force measurement of the body on the ground), but our inability to quantify forces exerted by organisms in the water has made it very difficult to understand the functional significance of different body and fin shapes.
This study adopts from the field of engineering a new flow visualization technique called Digital Particle Image Velocimetry (DPIV) and modifies it to study fish body and fin motion. This technique provides, for the first time, a means of experimentally quantifying water movement in the wake of freely swimming fishes, and calculating the magnitudes and directions of forces exerted on the water by fins and the body of freely-moving aquatic organisms. Progress on previous NSF grants has demonstrated the ability of DPIV to provide data critical to understanding mechanisms of aquatic locomotion in organisms, and has shown how using this new approach to measuring the motion of water leads to previously unexpected insights into the diversity of aquatic organisms. The general objectives of this research are to study the hydrodynamic function of fins in fishes, focusing on the dorsal and caudal fins in sunfish, trout, and sturgeon with the aim of testing several long-standing hypotheses in the literature regarding the mechanisms by which these fins generate force and allow fishes to maneuver and position themselves in the water. Of special interest is the hypothesis of "wake interception" : that fishes can enhance the force generated by their tail fin by having the tail intercept the hydrodynamic wake shed by the dorsal fin. If this hypothesis is corroborated, it will represent an important new general mechanism by which both organisms and man-made submersibles could increase their propulsive efficiency.
This research project contributes to advanced training of undergraduates in new approaches and technologies for the study of animal biomechanics and evolution through individual student research projects in an advanced undergraduate course co-taught by the Principal Investigator (PI), the interdisciplinary training of biology graduate students in engineering approaches to the study of organismal function, and post-doctoral training for the next generation of academic faculty. The research proposed here will have increased breadth of impact through a broad new training program in biomechanics at Harvard University which integrates biomechanics graduate training in biology, chemistry, physics, and engineering. The PI is one of the faculty on this grant, and the research proposed will serve as projects for students undertaking mandatory rotations, thus introducing a wide diversity of chemistry, physics and engineering graduate students to concepts and approaches in organismic functional biology that they would not otherwise be exposed to.

EFRI-BSBA: Multifunctional materials exhibiting distributed actuation, sensing, and control: Uncovering the hierarchical control of fish for developing smarter materials


PI Name: Michael Philen

Institution: Virginia Polytechnic Institute and State University

Proposal No. 0938043

Abstract

Fish have a remarkable ability to maneuver in tight places, perform stable high acceleration maneuvers, hover efficiently, and quickly brake as a result of a complex muscular system that comprises more than half of the body mass. Additionally, fish have an extraordinary ability to sense minuscule changes in fluid flow through neuromasts in the lateral line which has been shown to allow fish to detect, localize, and track prey, perform synchronized schooling maneuvers, provide feedback control for efficient locomotion, and form hydrodynamic images of the environment which enable the fish to characterize entities in the vicinity. However, there is still very little understanding of the structure and organization of the hierarchical control systems or of how these actuation and sensing systems are integrated to perform steady and maneuvering locomotor tasks. Furthermore, there has been little effort to transform the biological concepts related to the sensing, actuation, and control of fish into truly bioinspired and biomimetic engineered materials and systems.
This research aims to identify and theoretically describe the computational processing performed at the local sensory level for muscle activation and vertebral-stiffness modulation along the tail structure of fish for locomotion. Through a series of interdisplinary engineered experiments, the research seeks to understand (a) the ability of fish to actively modulate the mechanical properties of the tail via muscle recruitment, (b) how swimming gaits are regulated by a hierarchy of control systems that involve the visual, vestibular, and neuromast sensory systems, and (c) how hydrodynamic stimuli to the lateral line neuromasts directly influence the mechanical properties of the tail.
An advanced multifunctional material system having distributed actuation and sensing will be developed to serve as a platform for validation and to provide greater understanding of the biology of these systems. The new material system will utilize innovative artificial neuromasts (sensors) and muscles (actuators) that are distributed and arranged as inspired by the configuration found in fish. The artificial neuromast will consist of a cluster of nanowires acting as hairs attached to ionic polymer artificial neurons to create robust, flexible, sensitive, and dynamically responsive sensors for fluid flow detection. The biologically inspired actuation provided by the multifunctional material utilizes a distribution of micron flexible matrix composite actuators in the material system. Through coupling of the biological and engineering experiments of the fish and artificial material system, the interdisplinary team will work together to develop a new framework for observing, identifying, and predicting the sensorimotor behavior of fish for locomotion and stiffness modulation.
This research will advance the state-of-the-art development of multifunctional materials, leading to new structures that can intelligently sense and actuate a network of distributed robust sensors and actuators. Pioneer efforts include developing an advanced material system using nanotechnology and advanced composite technology, fabricating hierarchically structured sensors, creating new tools for bio-engineering investigations, and instigating a paradigm shift in the understanding of the organization and structure of the hierarchical control fish use for sensing and maneuvering.

Through collaborative efforts, an intellectual framework for education in K-12 classrooms, undergraduate research, and recruitment of minorities will be developed and implemented. One goal of the proposed education plan is to achieve broad impact on students? learning through dissemination of knowledge through K-12 programs at Harvard?s Museum of Natural History. A traveling exhibit will be developed on robotic fish that showcases the biology of aquatic propulsion, new actuator and sensing technologies and how these can be integrated to design a robotic fish. Assessment will establish measurable learning objectives and provide data on learning and improvement of the educational modules.

In the traditional view, the nervous system performs the computational "heavy lifting" in an organism. This view neglects, however, the critical role of biomaterials, passive mechanical physics, and other pre-neuronal or non-neuronal systems. Given that neurons consume forty times more energy per unit mass than structural materials such as bone, it is better, when possible, that biological systems employ relatively inexpensive structural materials rather than relying on more costly neuronal control. In this "bone-brain continuum" view, animal intelligence and behavioral control systems can only be understood using integrative modeling approaches that expose the computational roles of both neural and non-neural substrates and their close coupling in behavioral output. To this end, a group of researchers from Northwestern University, The Johns Hopkins University, and Harvard University propose to create a unique high fidelity neuromechanical model of a vertebrate. The effort is divided between the development of a general purpose computational tool set for neuromechanics research and application of these tools to an ideally suited model system, weakly electric knifefish.

The research will lead to breakthroughs in fundamental problems of how nervous systems work together with biomechanics to generate adaptive behavior. The final goal of the research is to construct an integrated neuromechanical model of a unique biological system - weakly electric knifefish - that places biomechanics and neural control on equal footing. Prior such neuromechanical models have used highly simplified models of mechanics and highly abstracted neuronal control approaches. This research advances the state of the art by incorporating high-fidelity mechanics with neuronal mechanisms motivated by direct neurophysiological evidence. Ultimately, this computational approach will help elucidate how animals distribute computations between brain and bone.

The skin of sharks is unique among vertebrate animals because it contains tooth-like scales, called dermal denticles, that create a hard external armor. These tooth-like denticles evolved over millions of years and equip the shark with hydrodynamic skin that reduces the cost of moving through the water. This advanced streamlining is currently a subject of great interest, with many industries attempting to take advantage of shark skin technology to create more efficient swimming designs. This project aims to provide a complete integrated understanding of shark denticles: how they form in embryonic sharks, how denticle shape has changed over years of evolution, and which denticle types are the best for drag-reduction and further design advances. This knowledge will enable better use of shark skin technology to make advanced design solutions that help to make a better and more environmentally friendly world. For example, one possible use of shark skin technology is the development of surface structures on airplanes or boats to reduce drag during movement and decrease fuel emissions. In addition to its scientific impact, this project has impact on the STEM workforce by supporting principal investigators and trainees across a wide range of career stages and by providing a unique, much-needed accessible research training program for undergraduates with disabilities in interdisciplinary research.

The shape and pattern of shark skin teeth, or denticles, has been refined over millions of years of evolution for functional improvements in aquatic locomotion. This project addresses the evolutionary and developmental trajectories that have led to a vast diversity of shark skin denticle types with the goals of determining why sharks have different shaped denticles among and within species and what functional advantages these different denticle shapes might offer these animals. From an integrated developmental, genetic, and evolutionary framework, the project will investigate how denticles develop and what factors lead to changes in shape. The approach will include studies of embryonic denticle development from the level of single cell transcriptomics to phenotypes and function to learn what key genes are essential to the production of various denticle shapes in a range of shark species and how these shapes are achieved via developmental innovation. Goals include understanding what shapes are most efficient for drag-reduction in both modern and extinct species to enable modeling and testing of new engineering designs to reduce drag in air- and water-borne vehicles and devices. Combining 3D printing with engineering methods, new shark-inspired surface structures will be used to create a shift in design solutions for a changing and more environmentally friendly world.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.