The long-term goal of this project is to interrogate the dynamics of membrane voltage in the context of intact brains with high spatiotemporal resolution. Optical methods to dissect neuronal activity promise to revolutionize our understanding of the brain at the cellular and circuit level; however, our understanding remains incomplete due, in part, to a lack of tools that can report directly on neuronal activity with sufficient speed and sensitivity. We propose to use the power of molecular design and organic chemistry to develop and apply new optical tools for monitoring membrane potential with unprecedented speed and sensitivity in intact brains and without disruptive capacitive load associated with other classes of voltage indicators. We plan to exploit photoinduced electron transfer (PeT) through molecular wires as a versatile platform for optical voltage sensing. We will build a palette of colors for optical voltage sensing that extends into the near infrared regions of the electromagnetic spectrum; we will create new voltage sensors with exceptionally high two-photon absorption cross sections for use in thick tissue and intact brains; and we will explore methods for genetically targeting and localizing ultra- sensitive fluorescent voltage sensors to neurons of interest. Throughout, development of molecular tools will be closely wed to applications in neurons and tissues, and we will apply these tools to understand how membrane potential dynamics change in both healthy and neurological disease states.

Public Health Relevance

The coordinated firing of millions of neurons in the human brain gives rise to the diverse set of experiences, emotions, thoughts, and sensations that make up the human condition. Despite the central importance of neuronal physiology to human health and disease, our understanding of this complex field remains incomplete due to a lack of tools that can reliably report on membrane potential. This proposed research will develop and apply new optical tools to study neuronal membrane potential in cells and in circuits.

National Institute of Health (NIH)
National Institute of Neurological Disorders and Stroke (NINDS)
Research Project (R01)
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Study Section
Special Emphasis Panel (ZRG1)
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Leenders, Miriam
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University of California Berkeley
Schools of Arts and Sciences
United States
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Kulkarni, Rishikesh U; Vandenberghe, Matthieu; Thunemann, Martin et al. (2018) In Vivo Two-Photon Voltage Imaging with Sulfonated Rhodamine Dyes. ACS Cent Sci 4:1371-1378
Kulkarni, Rishikesh U; Miller, Evan W (2017) Voltage Imaging: Pitfalls and Potential. Biochemistry 56:5171-5177
Kulkarni, Rishikesh U; Kramer, Daniel J; Pourmandi, Narges et al. (2017) Voltage-sensitive rhodol with enhanced two-photon brightness. Proc Natl Acad Sci U S A 114:2813-2818
Liu, Pei; Grenier, Vincent; Hong, Wootack et al. (2017) Fluorogenic Targeting of Voltage-Sensitive Dyes to Neurons. J Am Chem Soc 139:17334-17340