1982 — 1985 |
Nicholson, Charles |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
Comparative Study of Spreading Depression in the Retina and the Cerebellum @ New York University Medical Center |
0.958 |
1985 |
Nicholson, Charles |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Neuronal Modulation by Applied Electric Fields
When currents of sufficient amplitude are passed through brain tissue, the activity of neurons can be modulated. This is the basis of the most commonly used methods of stimulating the brain; however there has been little systematic quantitative study on how the current field couples to a neuron. The questions that I wish to examine are how neuronal geometry and orientation, with respect to a current field, influence the "capture" of current by a cell and how the type of field itself (steady, periodic; spatial distribution) affects the probability of neuronal modulation. In essence I want to know whether specific cells can be selectively modulated by the application of suitably chosen current fields. The methods are based on exploiting the well known geometrical organization of the cerebellar cortex and its neurons in three preparations: the in vivo rat, the in vitro turtle and the guinea pig brain slice. Currents will be a) steady b) periodic c) aperiodic. Neuronal responses will be measured by a variety of conventional techniques including intracellular recording, and extracellular unit, field potential and K+ measurement. The distribution of applied fields will be mapped along with the local impedance properties of the tissue. Concommitantly with the experimental studies, a theoretical analysis of the problem will be made using cable theory and appropriate field equations. A major objective of this work is to combine the experimental and theoretical aspects. The study involves the disciplines of neurophysiology and biophysics. The results of the project will relate to two areas; a) a better description of the biophysics of nerve tissue, b) improved information on how to selectively excite, or inhibit, specific nerve cells using appropriately designed current fields. These topics are directly related to he clinical use of electrical stimulation and to problems of the role of current flow in development and regeneration.
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1 |
1989 — 1992 |
Okada, Yoshio Nicholson, Charles Llinas, Rodolfo |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
Acquisition of a High-Resolution Neuromagnetometer @ University of New Mexico
The acquisition of a high-resolution neuromagnetometer will be utilized to study how active tissue in the brain generates magnetic currents observable outside the brain and how these currents related to cellular occurrences within the tissue. Specifically, this study will analyze: 1) the ionic and structural origin of spontaneous oscillation in the olive- cerebellum system, 2) the current patterns that precede speeding depression and anoxia in cerebellum and retina, and 3) correlations between current generation int he brain and resulting magnetic fields.
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0.975 |
1990 — 2013 |
Nicholson, Charles |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Diffusion of Substances Through the Brain @ New York University School of Medicine
DESCRIPTION This project will characterize and quantify the diffusion of molecules in brain extracellular microenvironment (BEM). The results will also reveal the geometry of the extracellular space and how substances are removed by uptake processes. The work will use a micropipette as a point-source to release molecules into the brain by iontophoresis, a pressure pulse or a controlled infusion. The subsequent distribution of the molecules will be measured using ion-selective microelectrodes (for tetramethylammonium and potassium), fast scan cyclic voltammetry (for dopamine) and integrative optical imaging (for fluorescent dextrans and albumins). Experiments will be made on the rat cortical slice, the isolated turtle cerebellum and the anesthetized frog. There are 3 specific aims: 1) To analyze the structural properties of the BEM. This will seek to discover if some regions are inaccessible to large molecules but not to small ones and whether hyaluronate or similar molecules impede diffusion. Other experiments will explore the transition from diffusion to bulk flow when molecules are infused into the brain at increasing rates and investigate whether there is evidence for endogenous bulk flow in the brain. 2) To compare regional uptake kinetics and diffusion of dopamine. Using an extension of the diffusion equation with Michaelis Menten uptake kinetics to interpret the data, dopamine diffusion in the striatum, nucleus accumbens, substantia nigra and ventral tegmental area will be studied. Uptake blockers will be used to further characterize the kinetic properties. 3) To quantify the contribution of spatial buffering to potassium homeostasis. The diffusion equation will be extended to accommodate spatial buffering according to the methods of Gardner-Medwin and the point source paradigm will be used to determine the contribution of the spatial buffer to removal of potassium from the BEM under different conditions. Blockers of the inward rectifier channels responsible for the spatial buffer and the role of gap junctions will be tested. Further experiments will investigate other mechanisms for potassium homeostasis such as KCl uptake. This study is relevant to nonsynaptic communication between cells by means of diffusing chemical messengers, the characterization of the role of diffusible factors in development, dopamine replacement therapies to alleviate Parkinson's disease, prevention of potassium-induced cell damage and the formulation of strategies for drug delivery to the brain.
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1 |
2015 — 2018 |
Ramirez-Marquez, Jose Emmanuel Barker, Kash [⬀] Nicholson, Charles Lambert, James Albert Mclay, Laura |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
Crisp Type 2/Collaborative Research: Resilience Analytics: a Data-Driven Approach For Enhanced Interdependent Network Resilience @ University of Oklahoma Norman Campus
Recent natural disasters have challenged our traditional approaches of planning for and managing disruptive events. Today, social media provides an opportunity to make use of community-driven data to help us understand the resilience, or lack thereof, of community networks (e.g., friends, neighborhoods) physical infrastructure networks (e.g., transportation, electric power) and networks of service providers (e.g., emergency responders, restoration crews). This Critical Resilient Interdependent Infrastructure Systems and Processes (CRISP) collaborative research integrates multiple disciplinary perspectives in engineering, computer science, and social science to address how community-driven data can help (i) understand the behavior of these interdependent networks before, during, and after disruptions, and (ii) more effectively reduce their vulnerability to and enhance their recovery after a disruption. The results will significantly improve our understanding and management of infrastructure recovery from natural disasters.
Two research components comprise this effort in resilience analytics. The first component creates a network model of the interdependence of infrastructure networks, the community networks that they serve, and the service networks engaged to respond after a disruption. We will explore the functional relationships between community resilience and infrastructure network performance. Model results will enable decision makers to understand the balance of resilience across the several networks and regions. The second component integrates the interdependent network model with community-sourced data to develop a framework of data analytics to better understand and plan for resilience. This component builds on research in the field of socio-technical systems relating to the analysis of social media data monitored after a disruption. The methods will assess the value of information provided by crowd-sourced data with expertise of community social scientists. This project draws upon multiple methods across several disciplines. The multidisciplinary methods explored in this project are essential for a breakthrough in resilience analytics. This project aims at taking a significant step forward in our understanding of how real-time data from social media and other sources can describe, predict, and prescribe practices to manage interdependent networks in crises.
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0.936 |