Ken Berglund - US grants

Abstract

Optogenetic control of neuronal activity has become a driving force in neuroscience research but its clinical application has been limited due to the fact that delivery of physical light into the brain poses a technical burden. This proposal aims to develop novel optogenetic probes that can report neuronal activity in a non-invasive manner and provide neuromodulation throughout the brain.

This project will develop layers of spatiotemporal control over optogenetic activation by a diffusible chemical (drug) in combination with activity-dependent expression and activation. Neuromodulation will be delivered to neurons autonomously only when and where it is needed. These new reagents will offer two new versatile methods of probing neural circuitry in a noninvasive manner: optically reporting neural activity via bioluminescence and perturbing neural circuitry in a closed-loop fashion. This will be particularly important for conducting long term invivo studies and future clinical translation.

Project Summary/Abstract The proposal aims to acquire an integrated multi-photon live imaging system that is also capable of simultaneous in vitro and in vivo electrophysiology. The system will consist of three main components: 1) a two-photon microscope including an ultrafast IR laser for multi-photon excitation, a laser scanning head, optics, an air table, an acquisition computer and software; 2) patch clamp equipment including an amplifier, software, a digital acquisition system, and manipulators; and 3) multiple imaging platforms for various samples including microscopic slides, dissociated single live cells, live tissue (i.e. a brain slice), and brain of a behaving animal. The system will be a multi-purpose rig for various projects and is intended to be shared primarily by a group of investigators within the Emory Neuromodulation and Technology Innovation Center and Emory/Georgia Tech Biomedical Engineering Departments, but will also be available to investigators in other departments. We combine interdisciplinary approaches to understand neural circuits underlying brain functions (e.g. tactile and auditory sensation) as well as to develop interventions for various neurological and psychiatric disorders in rodent models towards the treatment of human conditions (e.g. epilepsy, stroke, depression, Parkinson?s disease). We dissect these mechanisms at molecular and cellular levels and then evaluate neural circuits in whole animals. This system can be used for in vitro imaging in single cells or in acute brain slices while simultaneously monitoring neuronal electrical activity through patch clamp recording. It can be also used for in vivo imaging, such as calcium and membrane potential imaging in the brain to monitor activity of large numbers of neurons at a time, and in vivo optogenetic photostimulation in an awake, behaving animal to study neural circuits underlying animal behavior and diseases. In addition to physiological experiments, the microscope will also serve for histology using a whole, uncut brain treated with a tissue-clearing reagent (i.e. the CLARITY method). This method provides unperturbed morphology of neurons and circuits from the deep brain when two-photon excitation is utilized. Thus, the proposed system is intended to maximize capability to examine brain function in normal and disease conditions at different levels seamlessly. Currently available microscopes in our labs do not have such capability and microscopes in the university?s core facilities are designed for the single purpose of imaging and lack physiology capability, justifying an eminent need for the proposed system.