Engineering Neuronal Network Connectivity Through Precise and Scalable Electrical Modulation

Achieving precise and scalable control of neuronal connectivity is a key requirement for next-generation neurotherapeutic and neuroengineering applications. Yet, implementing Hebbian-like plasticity rules and verifying induced changes at a larger scale remain technically challenging. Here, high-density microelectrode arrays (HD-MEAs) are combined with programmable stimulation and analytics to induce and confirm targeted connectivity changes across multiple different in vitro and ex vivo preparations. Conditional Activity Metrics (CAM) are introduced to quantify stimulation-evoked changes in relative timing and spiking density between spike train pairs. CAM changes strongly correlated with synaptic weight changes in simulations. Experimentally, we observed robust synaptic strengthening/weakening in roughly 40% of 279 tested pairs following targeted stimulation. In a subset of pairs, tracked for extended durations, the induced effects persisted for at least 90 min. Synaptic modifications were also directly validated by using simultaneous HD-MEA and patch-clamp recordings. This work establishes a foundation for precise, high-throughput neuronal circuit reconfiguration, offering a versatile platform for advancing fundamental neuroscience and enabling novel neurotherapeutic and biohybrid computing strategies.