BRAIN EAGER: Monitoring the Function of Individual Synaptic Contacts during Circuit Plasticity with Novel Optogenetic Sensors

University Of California-Davis, Davis CA

Investigators

Abstract

One of the primary challenges in neuroscience is to understand how sensory experiences drive the changes in brain circuits that underlie learning. Notably, the current lack of adequate tools to monitor the functional properties of individual synaptic connections has been holding back efforts to define how complex neuronal firing patterns drive changes in neuronal connectivity in the brain. This EAGER proposal is focused on the development and application of radically novel fluorescent probes to visualize integrated neural activity at individual synapses. If successful, these innovative probes will be transformative for the field; broad application of these probes by the neuroscience community will enable discovery of the rules that link sensory-driven neural activity to the structural changes in synaptic connectivity underlying learning. This knowledge would revolutionize current understanding of the dynamic changes in brain structure and function during learning. Furthermore, this project will foster close collaboration between groups of investigators with complementary expertise, and thus will create a vibrant environment for interdisciplinary training of the next generation of scientists. This EAGER proposal addresses one of the major unsolved problems in neuroscience: how complex patterns of neural activity at multiple synapses interact to drive experience-dependent changes in circuit connectivity. The specific goal is to develop and apply novel fluorescent probes for visualizing the history of neural activity at individual synapses. These innovative probes will facilitate mapping the function and structure of the neural circuitry underlying a specific physiological process or behavioral task. To accomplish this goal, a multidisciplinary approach will be used that incorporates genetic strategies, computation-guided protein design, two-photon imaging, and electrophysiology. First, candidate sensors will be generated through a high-throughput, multi-step sensor screening process. Next, the sensitivity and kinetics of the sensors will be characterized in neurons in vitro, ex vivo, and in vivo. Finally, the sensors will be implemented in brain slices to probe the activity-dependent mechanisms that drive the formation and stabilization of synaptic connections. Ultimately, these sensors will be used to define the activity-dependent mechanisms that drive circuit changes in vivo during complex behavioral tasks. The proposed research would provide much needed imaging tools of synaptic activity that are compatible with a variety of advanced imaging techniques, such as wide-field, confocal and two-photon microscopy, and would dramatically enhance understanding of how the history of neural activity at individual synapses and their neighbors can influence long-term stability of neural circuit connections.