Melina Hale - US grants

The objective of this project is to examine the structure and function of interneurons in the reticulospinal system controlling escape behavior in fishes. The neural circuit which triggers escape behavior is simple, involving relatively few cell types and cell numbers, making this an appropriate system to use as a case study in the reticulospinal control of locomotion. Several major goals of this project are to determine the neural components of the reticulospinal system for escape in zebrafish and to examine the functions of several classes of interneuron, commissural interneurons and descending interneurons, during the escape behavior. Cell ablation and in vivo calcium imaging with confocal microscopy will be used to address these goals. Larval zebrafish will be used as a model system for this study. They are ideal due to the near transparency of their bodies and the wealth of knowledge available on all aspects of their biology. This project will provide basic information on zebrafish neurobiology and on the roles of interneurons in reticulospinal systems.

Melina Elisabeth Hale
Proposal number: 0238464

Title: CAREER: Reticulospinal control of alternative startle behaviors.

The broad question this research addresses is: How do nerve cells in the brain and spinal cord control movement? The aim of this research is to determine the nervous system's control of a little-studied startle behavior called the S-start and to compare it to the model startle behavior. Experiments are conducted on larval zebrafish because they are transparent, making it possible to look into the brain and spinal cord in the live, intact animal. With combined fluorescence microscopy and high-speed video analysis, the activity of nerve cells and movement pattern of the animal will be viewed simultaneously to determine in which behaviors specific nerve cells function. Individual cells will also be removed from the brain or spinal cord to test their roles in behavior. Data on behavior suggests that the two types of startle behavior will be controlled by different sets of nerve cells. However, because the two behaviors are under the same adaptive constraints--they need to be fast and reliable to prevent the escaping fish from being captured or injured by a predator--organizing principles of their nervous control will be similar. By determining how alternative types of startle behaviors are controlled by the nervous system, this research provides a foundation of information on this evolutionarily important behavior. This work has several educational goals. At the undergraduate level, this program brings cutting-edge technology into the classroom and students into the research laboratory. At the middle-school level, this program will examine issues of how animals move with minority girls from communities on the south side of Chicago. By illustrating movement control through the biology of familiar conditions, such as spinal-cord injury and stroke, a specific goal is to empower students to learn about their bodies and conditions that affect their lives.

[unreadable] DESCRIPTION (provided by applicant): Most vertebrate behaviors depend on the coordinated activity of many neurons in the brain and/or spinal cord. While the organization and function of single iterations of spinal cord circuits have been examined, it is unknown how interneuron populations distributed across segments generate functional behaviors. The goal of this research is to examine the longitudinal distribution of spinal cord interneurons and the roles of those interneuron populations in behavior. This work takes advantage of novel techniques for neuron imaging in the larval zebrafish model system, including cell population activity imaging and cell-specific ablation techniques, to test hypotheses of interneuron organization and function. Aim 1 examines the longitudinal distributions of spinal cord interneurons testing the hypothesis that there is a rostrocaudal gradient in cell and population size of descending interneurons in motor circuits. Aim 2 determines the roles of descending interneurons in behavior. Cell-specific lesioning is used to remove a population of interneurons and behavior is assessed before and after those ablations. Aim 2 tests the hypotheses that removing descending excitatory interneurons will decrease bending amplitude, angular velocity, angular acceleration and, for rhythmic movements, disrupt the pattern of axial wave propagation. This is the first test of the roles of spinal interneurons in vertebrates. Aim 3 bridges Aim 1 and Aim 2 to address how interneurons effect their behavioral roles by imaging cell activity across a population of neurons downstream of the ablated cells. We hypothesize that ablating excitatory startle interneurons will decrease activity of interneurons and motoneurons in the ablation region in proportion to the number of ablated cells but will not alter caudal activity. We hypothesize that that ablating excitatory swim interneurons will decrease interneuron activity in and caudal to the region of the ablations. The aims of this proposal address fundamental questions about interneuron population function in behaviors by testing the roles cells and in movement and in circuit function. By providing basic information on the neural control of movements, this work provides a foundation of information on how populations of interneurons function together to coordinate movement. Such work is critical for understanding the neural basis of movement disruption through injury and disease. [unreadable] [unreadable]

Animal behavior is driven by interconnected circuits of nerve cells in the brain and the spinal cord. Although diversification of these networks through evolutionary history has led to the incredible range of behaviors we observe in animals today, little work has been done to address the fundamental question: How do neural circuits evolve? One way in which neural circuits may change is through the addition of new nerve cells to the brain and their subsequent incorporation into functional networks. This research uses the startle neural circuit of fish to explore the effects of adding new nerve cells to circuits. The startle circuit is advantageous to use as a case study for examining mechanisms for changing circuits because it includes relatively few and easily identified nerve cells and controls a discrete and well-described behavior. New startle neurons will be genetically introduced into the hindbrain. Physiological recordings and laser ablation techniques will be used to examine the role specific cells play in the animal?s behavior. It is hypothesized that while new nerve cells make some connections into preexisting circuits other connections will be restricted and that redundancy of function within circuits may act to mask aberrant nerve cell activity, preventing it from disrupting behaviors. By investigating how new nerve cells integrate into simple neural circuits in the brain, this research will provide a case study for understanding principles by which circuits may be modified through evolution and insight into the flexibility for and constraints on such changes. The broader impact of this proposal includes outreach to middle school girls in disadvantaged areas of the south side of Chicago through activities in schools and in the research laboratory. In addition, this proposed research will involve undergraduates and graduate students, providing opportunities for training in a diverse array of scientific approaches and methodologies.

This Integrative Graduate Education and Research Traineeship (IGERT) project builds links broadly across Chicago's scientific community to develop an integrative training program for U.S. doctoral students in motor control and movement. To develop an integrative understanding of movement, it is necessary to address both the biology and the engineering of the systems involved and how they work together. Students from graduate programs at the University of Chicago and Northwestern University will obtain the biological and engineering backgrounds required to develop the integrative approach needed to take the field in new directions. Educational tools include a boot camp, a three-quarter common core curriculum, a discussion series, required laboratory rotations, and workshops and seminars at the Field Museum. The program will involve outreach to local Chicago-area schools, with training for students and faculty in the development and conduct of effective outreach. Mentoring of undergraduate students by IGERT graduate trainees will be done in close collaboration with local universities that primarily serve underrepresented minorities in the Chicago area. A trans-institutional website will highlight opportunities and results related to this program's IGERT goals and provide resources for teachers and students. IGERT is an NSF-wide program intended to meet the challenges of educating U.S. Ph.D. scientists and engineers with the interdisciplinary background, deep knowledge in a chosen discipline, and the technical, professional, and personal skills needed for the career demands of the future. The program is intended to catalyze a cultural change in graduate education by establishing innovative new models for graduate education and training in a fertile environment for collaborative research that transcends traditional disciplinary boundaries.

This NSF MRI Award funds the acquisition of a confocal microscope to expand the research capabilities of faculty at University of Chicago and at the Field Museum of Natural History for conducting research in the fields of organismal and evolutionary biology.Topics of study include examining the functions of ectopic neurons as models for exploring neural circuit evolution in zebrafish, germ band pattern development in flies, the response of plants to bacterial infection and the organization of song circuit neurons in birds. The microscope would provide essential imaging capabilities of cellular and sub cellular structures. The microscope benefits students by allowing them to gain experience in the application of research techniques in classes and independent projects. The results of the research and teaching efforts will be broadly disseminated through abstracts and peer reviewed publications, as well as by active participation of students and faculty at
professional meetings.

In animals, normal limb movements such as walking or reaching require sensory information from the limb regarding their movements and mechanics. While fishes use their limbs (or paired fins) for a diverse array of behaviors, little is known about the role sensory abilities plays in those functions. This project examines the fundamental question of how the sensory and motor elements of the fin propulsive system co-adapt to generate a functional neuromechanical system. In particular, it will determine how physical properties of the fins such as stiffness, size and shape, are reflected in the biological instrumentation of the fins for sensation. In addition to providing a new tractable model for studying integration of sensation and movement, data from this project will inform the design of fin-inspired propulsive devices for underwater vehicles. The broader impacts of this project will provide outreach experiences for children on the South Side of Chicago as well as opportunities for undergraduate and graduate training in the laboratory and builds educational activities at the Field Museum of Natural History.

An award is made to The University of Chicago to acquire and install a biplanar videofluoroscopy system that uses X-rays to measure 3-dimensional movements of the inside of animals through a method called X-ray Reconstruction of Moving Morphology (XROMM). XROMM generates 3D measurements and animations of biological movement by integrating 3D movement data collected using bi-planar digital videofluoroscopy with CT scan-based reconstructions of animal anatomy. XROMM makes it possible to measure movements of internal skeletal elements to which external markers cannot be attached without disrupting animal function, to study internal mechanics of small animals, such as mice, rats, and songbirds which are too small for external markers, to study animals that will only behave in optically opaque environment, such as in the dark, under soil, in water and/or in structurally complex environments, and to image internal soft tissue structures, such as muscles. The ability to make these measurements will enhance and expand research and training in integrative and evolutionary biomechanics, neuromechanics and neuroscience in the Chicago area. In particular, XROMM will enable innovations in the following areas: (1) Comparisons of locomotion and feeding movements of fish and amphibians in complex aquatic and terrestrial environments, and their relationship to evolutionary changes in form at the origin of tetrapods,(2) the diversity, complexity and control of 3D jaw and tongue movements during feeding in living mammals, and their relationship to changes in the structure of the feeding system during the origin and radiation of mammals, and (3) the role of the brain in control of 3D movements of a range of musculoskeletal organs, including jaws, tongues, eye muscles, and hands.

This research equipment will have multiple impacts beyond research, including teaching and training, public outreach and exhibit development, robotics and applied biomechanics. The XROMM instrumentation will provide postdoctoral researchers, graduate and undergraduate students with access to state-of-the-art research equipment in a dynamic intellectual environment that will make possible novel approaches to integrative analyses of animal movement. Graduate programs with access to XROMM will include: at the University of Chicago, the Graduate Program in Integrative Biology, the Committee on Evolutionary Biology, the Committee on Computational Neuroscience and the Committee on Medical Physics; at Northwestern University, the graduate programs in Biomedical Engineering, Physical Medicine & Rehabilitation, and Physiology; and the inter-institution, interdisciplinary NSF IGERT program, Integrative Training in Motor Control and Movement. Faculty and graduate students in these programs are actively involved in outreach locally (Sisters 4 Science; Global Village Science Project; Brain Day), and at national and international levels (Outreach programs in Fiji, New Guinea; Encyclopedia of Life Project; Biomechanics Exhibit, Field Museum of Natural History). The XROMM instrumentation will significantly augment these efforts by generating visually compelling animations of animal movement for presentation and online distribution. In making possible novel research into the role of the brain in control of movement, this equipment will contribute to understanding of motor control disorders including Parkinson's Disease and stroke.