Long-Term Potentiation and Closed-Loop Learning in Paired Brain Organoids for CNS Drug Discovery

Abstract

Learning and memory, central to cognitive function and critical targets for drug discovery in neurological disorders, fundamentally rely on synaptic plasticity, such as long-term potentiation (LTP). We developed an embedded electrode array (EEA) capable of supporting paired CNS-3D brain organoids, derived from human, induced pluripotent stem cells (iPSCs), that were interconnected via guided axonal growth, as a novel functional biomarker model for probing learning-related plasticity in vitro. Using open-loop stimulation protocols, a robust, network-level LTP in trained organoids was demonstrated that was not observed in untrained organoids. Importantly, LTP was enhanced in the presence of elevated levels of brain-derived neurotrophic factor (BDNF), and it was prevented by the NMDA receptor antagonist AP5. Furthermore, a closed-loop "maze-game", inspired by Pac-Man(R), demonstrated that paired brain organoids could learn to perform better in the game when given reinforcement feedback, and that this effect depended on BDNF. This integrated platform provides a human-relevant in vitro model of synaptic plasticity and cognitive function, establishing a functional biomarker platform for central nervous system (CNS) drug discovery and linking game performance as a measurable readout of learning-related plasticity to the emerging field of organoid intelligence.