Our laboratory conducts research into how information about the outside world is encoded by the patterns of spiking neurons in the sensory pathways of the brain. We combine experimental and computational approaches to better understand and control aspects of the neural code. Specifically, we focus on the visual and somatosensory pathways at the junction between the sensory periphery and sensory cortex. Our experimental approaches include multi-site, mutli-electrode recording, optical imaging, behavior, and patterned stimulation. Our computational approaches include linear and nonlinear model estimation, information theory, observer analysis, and signal detection and discrimination. Our long-term goal is to provide surrogate control for circuits involved in sensory signaling, for pathways injured through trauma or disease.
Quantitative Evolutionary Genetics. After 15 years working on genomic approaches to complex traits in Drosophila, my group has spent much of the past 10 years focusing on human quantitative genetics. We start with the conviction that genotype-by-environment and genotype-by-genotype interactions are important influences at the individual level (even though they are almost impossible to detect at the population level). We use a combination of simulation studies and integrative genomics approaches to study phenomena such as cryptic genetic variation (context-dependent genetic effects) and canalization (evolved robustness) with the main focus currently on disease susceptibility.
Immuno-Transcriptomics. As one of the early developers of statistical approaches to analysis of gene expression data, we have a long-term interest in applications of transcriptomics in ecology, evolution, and lately disease progression. Since blood is the most accessible human tissue, we’ve examined how variation is distributed within and among populations, across inflammatory and auto-immune states, and asked how it relates to variation in immune cell types. Our axes-of-variation framework provides a new way of monitoring lymphocyte, neutrophil, monocyte and reticulocyte profiles from whole peripheral blood. Most recently we have also been collaborating on numerous studies of specific tissues or purified cell types in relation to such diseases as malaria, inflammatory bowel disease, juvenile arthritis, lupus, and coronary artery disease.
Predictive Health Genomics. Personalized genomic medicine can be divided into two domains: precision medicine and predictive health. We have been particularly interested in the latter, asking how environmental exposures and gene expression, metabolomic and microbial metagenomics profiles can be integrated with genome sequencing or genotyping to generate health risk assessments. A future direction is incorporation of electronic health records into genomic analyses of predictive health. Right now it is easier to predict the weather ten years in advance than loss of well-being, but we presume that preventative medicine is a big part of the future of healthcare.
Manufacturing, Mechanics of Materials, Bioengineering, and Micro and Nano Engineering. Advanced manufacturing and materials processing of metallic, polymeric, ceramic, and composite materials for applications in life sciences, propulsion, and energy.
Professor Das directs the Direct Digital Manufacturing Laboratory and Research Group at Georgia Tech. His research interests encompass a broad variety of interdisciplinary topics under the overall framework of advanced design, prototyping, direct digital manufacturing, and materials processing particularly to address emerging research issues in life sciences, propulsion, and energy. His ultimate objectives are to investigate the science and design of innovative processing techniques for advanced materials and to invent new manufacturing methods for fabricating devices with unprecedented functionality that can yield dramatic improvements in performance, properties and costs.
The biomechanics of locomotion of organisms and robots on and within complex materials. Physics of granular media.
My research integrates my work in complex fluids and granular media and the biomechanics of locomotion of organisms and robots to address problems in nonequilibrium systems that involve interaction of matter with complex media. For example, how do organisms like lizards, crabs, and cockroaches cope with locomotion on complex terrestrial substrates (e.g. sand, bark, leaves, and grass). I seek to discover how biological locomotion on challenging terrain results from the nonlinear, many degree of freedom interaction of the musculoskeletal and nervous systems of organisms with materials with complex physical behavior. The study of novel biological and physical interactions with complex media can lead to the discovery of principles that govern the physics of the media. My approach is to integrate laboratory and field studies of organism biomechanics with systematic laboratory studies of physics of the substrates, as well as to create mathematical and physical (robot) models of both organism and substrate. Discovery of the principles of locomotion on such materials will enhance robot agility on such substrates.
Biomechanics, mechanobiology, glaucoma, ophthalmology, osteoarthritis, regenerative medicine
Biomechanics and mechanobiology, glaucoma, osteoarthritis, regenerative medicine, intraocular pressure control, optic nerve head biomechanics.
We work at the boundaries between mechanics, cell biology and physiology to better understand the role of mechanics in disease, to repair diseased tissues, and to prevent mechanically-triggered damage to tissues and organs. Glaucoma is the second most common cause of blindness. We carry out a range of studies to understand and treat this disease. For example, we are developing a new, mechanically-based, strategy to protect fragile neural cells that, if successful, will prevent blindness. We are developing protocols for stem-cell based control of intraocular pressure. We study the mechanobiology and biomechanics of neurons and glial cells in the optic nerve head. We also study VIIP, a major ocular health concern in astronauts. Osteoarthritis is the most common cause of joint pain. We are developing paradigms based on magneto-mechanical stimulation to promote the differentiation and (appropriate) proliferation of mesenchymal stem cells.
Dr. LaPlaca’s broad research interests are in neurotrauma, injury biomechanics, and neuroengineering as they relate to traumatic brain injury (TBI). The goals are to better understand acute injury mechanisms in order to develop strategies for neuroprotection, neural repair, and more sensitive diagnostics. More specifically, the lab studies mechanotransduction mechanisms, cellular tolerances to traumatic loading, and plasma membrane damage, including mechanoporation and inflammatory- & free radical-induced damage. We are coupling these mechanistic-based studies with –omics discovery in order to identify new biomarker candidates. In addition, Dr. LaPlaca and colleagues have developed and patented an abbreviated, objective clinical neuropsychological tool (Display Enhanced Testing for Cognitive Impairment and Traumatic Brain Injury, DETECT) to assess cognitive impairment associated with concussion and mild cognitive impairment. An immersive environment, coupled with an objective scoring algorithm, make this tool attractive for sideline assessment of concussion in athletic settings. Through working on both basic and clinical levels she is applying systems engineering approaches to elucidate the complexity of TBI and promoting bidirectional lab-to-clinical translation.
All organisms use chemicals to assess their environment and to communicate with others. Chemical cues for defense, mating, habitat selection, and food tracking are crucial, widespread, and structurally and functionally diverse. Yet our knowledge of chemical signaling is patchy, especially in marine environments. In our research we ask, "How do marine organisms use chemicals to solve critical problems of competition, disease, predation, and reproduction?" Our group uses an integrated approach to understand how chemical cues function in ecological interactions, working from molecular to community levels. We also use ecological insights to guide discovery of novel pharmaceuticals and molecular probes.
In collaboration with other scientists, our most significant scientific achievements to date are: 1) characterizing the unusual molecular structures of antimicrobial defenses that protect algae from pathogens and which show promise to treat human disease; 2) understanding that competition among single-celled algae (phytoplankton) is mediated by a complex interplay of chemical cues that affect harmful algal bloom dynamics; 3) unraveling the molecular modes of action of antimalarial natural products towards developing new treatments for drug-resistant infectious disease; 4) discovering that progesterone signaling and quorum sensing are key pathways in the alternating sexual and asexual reproductive strategy of microscopic invertebrate rotifers - animals whose evolutionary history was previously thought to preclude either cooperative behavior (quorum sensing) typically associated with bacteria and hormonal regulation via progesterone typically seen in vertebrates; 5) identifying a novel aversive chemoreception pathway in predatory fish that results in rapid recognition and rejection of chemically defended foods, thereby protecting these foods (prey) from predators.
Ongoing projects include: 1) Waterborne chemical cues in the marine plankton: a systems biology approach (including metabolomics); 2) Exploration, conservation, and development of marine biodiversity in Fiji and the Solomon Islands (including drug discovery, mechanisms of action, and chemical ecology); 3) The role of sensory environment and predator chemical signal properties in determining non-consumptive effect strength in cascading interactions on oyster reefs; 4) Regulation of red tide toxicity by chemical cues from marine zooplankton; 5) Chemoreception of prey chemical defenses on tropical coral reefs.
Most biological traits have a strong genetic, or heritable, component. Understanding how genetic variation influences these phenotypes will be important for understanding common, heritable diseases like autism. However, the genetic architecture controlling most biological traits is incredibly complex – hundreds of interacting genes and variants combine in unknown ways to create phenotype. The McGrath lab is interested in using fundamental mechanistic studies in C. elegans to identify, predict, and understand how genetic variation impacts the function of the nervous system. We are studying laboratory adapted strains and harnessing directed evolution experiments to understand how genetic changes affect development, reproduction, and lifespan. We combine quantitative genetics, CRISPR/Cas9, genomics, and computational approaches to address these questions. We believe this work will lead to insights into evolution, multigenic disease, and systems biology.