John Troy - US grants

The long-term objective of this research project is to fully characterize the retinal input to the mammalian brain. This information is essential if we hope to restore vision, either through synthetic or biological means, to those blinded through retinal diseases. Through decades of research we have learned much about how the mammalian retina encodes the visual world, but substantial gaps in our knowledge remain before realistic quantitative models of retinal image coding can be developed. The research proposed in this application seeks to fill two of these gaps. First, evidence is growing which threatens the foundation of our understanding of how the eye encodes visual information. Traditionally, retinal ganglion cells have been though to transmit neural messages by independently modulating their rates of discharge of action potentials. Simultaneous recordings from pairs or more of neurons in cats and other vertebrates have shown, however, that the spike trains of retinal ganglion cells are temporally correlated. The correlated firing events have the potential to encode more information than is possible were ganglion cells independent encoders of the visual scene. One major objective of this proposal is too determine whether a coding scheme based on correlated firing of cell groups is more plausible than one based on single cell firing for the mammalian retina. Second, a realistic model of how the retina represents visual images requires detailed information about the array of ganglion cell receptive fields and the spatiotemporal integrative properties of these fields. While we recently have very good quantitative descriptions of the spatiotemporal transfer functions of ganglion cells, we lack physiological maps of the array of ganglion cell receptive fields. Instead, we have anatomical maps of the array of ganglion cell dendritic fields. The other major objective of this proposal is to determine whether these anatomical maps can correctly substitute for the physiological maps which are more difficult to measure.

DESCRIPTION (provided by applicant): The goal of this project is to develop a nanoelectrode that can be used to record from and stimulate individual neurons of the intact brain. Such an electrode would permit neuroscientists to investigate, as never before accomplished, the role of single and groups of neurons in brain function. During any task, cognitive, motor, or perceptual, neurons discharge their action potentials in complex asynchronous patterns. The discharges are noisy and debate continues about how neural messages are encoded in neural discharge patterns. Without the ability to externally control the discharges of neurons independently of one another, something that is impossible with current technology, neuroscientists simply lack the tools needed to systematically attack the key question of how information is encoded in neuronal discharges. Without this basic understanding of how the discharges of neurons contribute to brain function, there is really no hope that artificial neural control systems could be developed which truly replicate the behavior of lost neural tissue. Modern techniques in nanofabrication will be used to build the nanoelectrodes. These techniques should permit the probes to be produced in mass quantities with uniform dimensions and physical and chemical properties. Templating techniques will be used, enabling a potentially wide array of nanostructures, including coaxial arrangements of different materials, to be fabricated with high reproducibility. The longterm objective of this work is to use nanoelectrodes in neuroprosthetic devices, providing designers with more precise control of neural activity than previously imaginable. If successful, the prospect of restorating close to normal function in human patients with neural disorders would take a big step forward.

This award supports a project that will improve instrumentation used for patch-clamp measurements for recording the electrical potential of individual cells. The patch-clamp method is the most widely used method for this purpose; 26,000 research publications have cited the method since 1975, half of these appearing in the last five years. Despite this widespread use, the method has a number of well known limitations that arise from the equipment used. In particular, it is difficult to obtain and to sustain more than one recording at a time, making studies of the electrical activity of individual members of cellular networks difficult. Moreover, the quality of recordings deteriorates with time, and the recording bandwidth is limited. Through the development of new instrumentation undertaken with the support of this award, long-duration, multiple-site recordings will be easier to obtain, and high bandwidth signals will be more accessible. Traditional patch clamp systems employ a glass pipette to contact the cell with an Ag/AgCl electrode located at a fixed position far from the pipette tip. Introduction of any cellular or other debris near the tip interferes with reliable measurement. In the device to be developed, a movable nanoelectrode can be advanced forward and through the tip to clear such debris. This modification alone is expected to alleviate most of the current patch clamp limitations. While the proposed device will be more complex than a standard patch clamp electrode, the project's goal is development of a device that will integrate easily into existing patch clamp systems. This approach of adapting the design to systems currently in use should encourage rapid acceptance of the new tool among electrophysiologists, significantly increasing the likely impact it will have on the progress of biological research over the next decade. The PI has been active in development of new curricula and other activities that serve both neuroscience and bioengineering. Because of the extensive use of the patch-clamp in a variety of areas of neuroscience and cell biology, successful development of the proposed device can be expected to have a broad impact on biological research.

ABSTRACT for EFRI-BSBA: Nanoactuation and Sensing of Neural Function for Engineering Future Biomimetic Retinal Implants and Therapies
PI: Laxman Saggere, Mechanical and Industrial Engineering, University of Illinois at Chicago (UIC)

Intellectual Merit

Retinal degenerative diseases such as age-related macular degeneration (AMD) affect over 10 million people in the US alone, causing a significant decline in the quality of their lives. Currently available therapies are at best only somewhat effective. Over the last two decades, several groups around the world have been pursuing the development of a retinal prosthesis, with the goal of providing a restorative aid for patients affected by retinal diseases due to photoreceptor degeneration. Nearly all of the current retinal prosthesis developments rely on the principle of stimulating the retina electrically, which is conceptually simple; however, a number of challenges still remain to be overcome in this approach and fully functional, long-lasting devices are not on the immediate horizon. On the other hand, a widely occurring mechanism of intercellular communication in the normally functioning retina as well as elsewhere in the nervous system is the chemical synapse. Inspired by the nature's complex mechanism of transducing visual information into chemical signals via the chemical synapse, the applicants envision an unconventional, but rational, approach to restore the lost functionality of photoreceptors: a light modulated chemical interface at the retina.

Toward this long-term vision of a chemically based retinal implant, the proposed project seeks to understand how the retina and retinal neurons respond physiologically to controlled focal presentation of chemical stimuli in vitro so that a general engineering framework for developing a prosthetic system based on the functionality of the diseased neurons can be further explored. There exist two distinct classes of chemicals, viz. native neurotransmitters and tethered synthetic biomolecules, that are promising as transmitters, and each offers certain unique advantages. Therefore, in this project, they propose to investigate the efficacy and feasibility of eliciting physiological responses of retinal neurons when focally stimulated by both types of chemicals delivered by means of specially engineered micro- and nanoscale delivery devices.

This novel approach is fundamentally different from the more common approach of electrically stimulating retinal neurons, and distinct from chemical-based strategies recently proposed by other groups. Thus, the main intellectual merit of this proposal lies in generating new scientific and technical knowledge that could be transformative to the development of a biomimetic retinal implant to restore lost or damaged retinal function. Ultimately, if successful, this research could lead to a new paradigm and breakthroughs in retinal prostheses.

Broader Impacts

The proposed project, if successful, could break new ground in the area of visual prosthesis and someday help provide vision perception to millions of people affected by retinal degenerative diseases. The devastating complications associated with vision loss, and the progressive aging of the US population with a corresponding increased incidence of AMD in otherwise healthy individuals, emphasize an urgent national need to develop effective prostheses and therapies for retinal degenerative diseases. Beyond the impact on vision health, this research could also lead to other novel drug delivery strategies and biomimetic therapies for treating a variety of neurological disorders such as Parkinson's.

The interdisciplinary collaboration of researchers with a diverse expertise in this project provides a unique opportunity and framework for interdisciplinary education and training of secondary school through postdoctoral students at the frontiers of engineering, neuroscience, and medicine. Four graduate students and one postdoctoral student will undertake interdisciplinary research addressing the tasks involved in this project in the investigators' labs across three different colleges at UIC. Several educational activities integrated with the proposed research including undergraduate research and outreach will be implemented.

PI: Liu, Shu Q.
Proposal Number: 1403036
Institution: Northwestern University
Title: Neuroprotective Engineering Based on Innate Responses to Stroke

Stroke is a prevalent disorder commonly caused by arterial plaques that block blood flow to the brain, resulting in brain injury, depression, mental retardation, and/or paralysis. The injured brain is often associated with bone-like structure formation, known as brain calcification, a process disrupting the brain structure and intensifying brain injury. To date, it remains poorly understood how stroke causes brain calcification and there are few approaches effective for prevention of brain calcification. In this application, the investigators intend to elucidate the role of a cell membrane-associated family of calcium-carrying molecules known as annexins in the induction of brain calcification in a mouse model of stroke. These molecules may move from the cell membrane to the intracellular contractile filaments when brain cells are injured to cause calcium deposition or calcification, as these molecules carry calcium ions. The investigators have discovered a liver-produced molecule known as trefoil factor 3 that potentially protects the injured brain from calcification by blocking annexin deposition. The significance of this discovery is that trefoil factor 3 may be potentially used as a drug to prevent brain calcification and injury in patients with stroke. In this project, the investigators will develop an engineering strategy for boosting trefoil factor 3 production in a mouse model of stroke by delivery of the trefoil factor 3 gene or protein and test the efficacy of the engineering approach for brain protection against annexin-dependent calcification. If successful, trefoil factor 3 can be produced by a biotechnology approach and applied to human patients with stroke to prevent brain calcification, thereby reducing brain injury and functional deficits. This effort may potentially lead to a reduction in stroke-induced human morbidity and mortality. In addition to these scientific aspects, the investigators will devote efforts to establish a new undergraduate education model integrating independent research into lecture topics. This form of education will allow students to understand scientific concepts from hands-on experience and to be more engaged in cutting-edge research, enhancing students creativity and capability of solving real-world problems.

Cerebral ischemia or ischemic stroke is a prevalent disorder commonly caused by cerebral artery thrombosis and/or atherosclerosis, resulting in cerebral injury and neurological deficits including depression, mental retardation, and/or paralysis. Ischemic stroke is often associated with cerebral calcification or hydroxyapatite deposition, a process disrupting neuronal structure and intensifying cerebral injury. To date, the mechanisms of cerebral calcification remain elusive and few approaches have been established for protecting the cerebrum from calcification. The investigators have found that a cell membrane-associated family of calcium-carrying molecules known as annexins may translocate from the cell membrane to the cytoskeletal microfilaments in ischemic neurons to facilitate hydroxyapatite formation. Furthermore, a liver-produced endocrine molecule known as trefoil factor 3 (TFF3) is upregulated in response to stroke, potentially protecting the ischemic cerebrum from calcification by blocking annexin deposition. In the proposed research, the investigators intend to achieve three aims: (1) evaluate the role of annexins A2, A3, and A5 in ischemic cerebral calcification and injury; (2) assess the role of TFF3 in protection of the ischemic cerebrum from annexin-dependent calcification and injury; and (3) establish neuroprotective engineering strategies based on the mechanisms of TFF3 action for maximizing protection against cerebral calcification in stroke. In a mouse model of ischemic stroke, the role of annexins will be evaluated by using siRNA-mediated loss-of-annexin and recombinant annexin-based gain-of-annexin approaches; the anti-calcification role of TFF3 will be tested by using a TFF3-/- mouse model with or without recombinant TFF3 administration; and the role of TFF3 in interference with annexin binding to neuronal micro-filaments will be assessed by molecular binding assays in the presence or absence of TFF3. Protective engineering approaches will be established based on TFF3 gene transfection and controlled TFF3 protein delivery technologies to boost TFF3 expression following ischemic stroke. These investigations will provide a foundation for understanding the mechanisms of ischemic cerebral calcification and establishing engineering technologies for protection against ischemic cerebral calcification and injury, thus potentially reducing stroke-induced human morbidity and mortality.

Machining is an essential component of the manufacturing process that has played a significant role in every industrial revolution. Machinists, as machine tool operators, are important members of the skilled technical workforce, and require long-term and professional training or education. As many new concepts and technologies are being introduced in the machining industry to satisfy the requirements of Industry 4.0, the corresponding revision of machinist training must also take place. This project will improve and modernize existing machinist training and education in response to the new requirements of the machining industry in the era of Industry 4.0. It is expected that the local machining industry, an important economic pillar of the Finger Lakes region in New York State, will benefit significantly from increasing the pool of available skilled workers and meeting the new demands of machining knowledge and skills.

The overall goals of this project are to 1) improve existing machining training and education programs in response to the skill and knowledge requirements of 21st century interdisciplinary themes, 2) modernize existing machinist training and education using innovative methods and advanced technologies to improve trainee engagement and learning efficiency, 3) expand the machining workforce by increasing the accessibility and flexibility of machinist training and education to various stakeholders, and 4) facilitate machinist training/education interworking and resource sharing among training providers. All project results will be disseminated throughout New York State as well as the entire United States through collaborations with New York Manufacturing Extension Partnership (NY MEP) and Boards of Cooperative Educational Services (BOCES) of New York State to maximize their impact. This project is funded by the Advanced Technological Education program that focuses on the education of technicians for the advanced-technology fields that drive the Nation's economy.

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.