Alzheimer?s disease (AD) causes a progressive loss of memory and cognition. In spite of sustained efforts over several decades, we lack the basic understanding of biophysical, physiological and pathophysiological mechanisms underlying AD pathology. Human cognition is controlled by a complex network of cells that are organized in a 3-dimensional architecture and the underlying neurological activity is heavily dependent upon the controlled and coordinated activity of precisely located membrane macromolecules, including channels and receptors. Indeed, cell membrane interactions of various amyloids, including amyloid beta, alpha-synuclein, FTD43 are primary drivers of AD pathophysiology. To obtain a complete understanding of the cellular behavior, in line with the goals of the AD initiative, technology enabling multi-modal and multi-scale structure-function imaging of live neuronal networks must be created to better understand the integrated neural activities. The structural connectivity and dynamic signal transmission within synaptic networks need to be understood in two fundamental ways: i) structural sub-components, including ion channels and receptors that propagate functional cellular signals and ii) their functional states. Our current understanding of the synaptic structure is limited to electron microscopy (EM) studies in fixed, dehydrated and metal-coated thin sections and which precludes real- time structural changes associated with the synaptic activity and brain function. The functional synaptic activity is currently examined by conventional electrophysiological setup. These studies have yet to elucidate the direct structure-function relationship at either individual synaptic level or at their interconnected clusters. Atomic force microscopy (AFM) allows imaging of native biological specimen in buffer at resolution equivalent to EM imaging and allows real-time introduction of agonists, including chemical, electrical, and mechanical while monitoring neuronal structures. However, current AFM technology is not developed to allow imaging of large areas and is limited to single point imaging and prohibits simultaneous high resolution imaging of connected networks. These connected networks coordinate the behavior of their ion channels to control membrane electrical potentials, producing one of the primary functional outputs of brain cells. The overall goal of this proposal is to develop a novel conducting atomic force microscopy (AFM)-array for simultaneous multi-point imaging with integrated electrical recording. As an initial application, we will study networks in cultured neurons. In order to accomplish our goals, we propose the following specific aims:
Aim 1 : Develop arrays of conducting AFM capable of imaging biological structures, Aim 2: Image live cultured neurons and synaptic networks, and Aim 3 Image structural and functional changes in response to various oligomeric amyloids, including amyloid beta, alpha-synuclein, FTD43 as well as our newly designed amyloid ion channel blockers which control memory loss in animals. Successful completion of this proposal will result in enabling technology that provides high-resolution imaging and increased understanding of synaptic networks linked with neurodegeneration and mental illness, especially AD.
Alzheimer?s disease (AD) is the world?s leading cause of dementia. In spite of tremendous efforts, no effective treatment is available. Present work will design an array of fully functional atomic force microscope (AFM0 and use them to obtain the FIRST high-resolution dynamic nanoscale structural and functional map of synaptic networks and their changes in response to various amyloids which form membrane pores and their blockers which is essential for our fundamental understanding of biophysical, physiological and pathophysiological mechanisms underlying AD pathology.
