Project summary Neurological disorders remain a major unmet medical need in the US and worldwide, accounting for significant societal burden and loss of healthy years of life. One barrier to discovery of effective therapeutics is the challenge of establishing scalable neurological disease models that effectively translate to clinical outcomes. Q-State has developed a platform that can execute phenotypic screens for genetically defined neurological diseases. Patient-derived induced pluripotent stem cells (iPSCs) are differentiated into a variety of neuronal types, and the activity of these cells is measured using optogenetic methods to stimulate and record electrical activity with single-cell resolution. The Firefly microscope, developed through Phase I and II efforts, enables widefield optical electrophysiology recordings of 100s of cells per well in a 96-well format, providing a ~10,000-fold increase in throughput relative to manual patch clamp. The throughput makes it practical to find genetically defined disease phenotypes in iPSC-derived neurons and to run screens for candidate therapeutics that rescue the disease phenotype. In the Phase IIB application, Q-State will adapt these technologies into an integrated high- throughput screening platform through four Aims. 1) We will build a 384-well compatible Firefly instrument that will both decrease cost by 4-fold and increase throughput by 4-fold. 2) We will implement a liquid handling system for automated differentiation, plating, and feeding of human iPSC-derived neurons in a 384-well plate format. 3) We will establish a human neuronal disease model for the genetically defined neurological disorder caused by dominant negative mutations in KCNQ2, which encodes a voltage-gated potassium channel. And 4) we will apply this platform to drug discovery by running a 14,000-compound screen for molecules that reverse the disease phenotype. At the conclusion of this Phase IIB work, the platform will be fully validated for executing affordable phenotypic drug screens and may generate chemical hits that can be developed for treating KCNQ2 encephalopathy patients.