An integrated in vitro platform and biophysical modeling approach for studying synaptic transmission in isolated neuronal pairs

Studying synaptic transmission is facilitated in experimental systems that isolate individual neuronal connections. We developed an integrated platform combining polydimethylsiloxane (PDMS) microstructures with high-density microelectrode arrays to isolate, record, and manipulate neuronal pairs from human induced pluripotent stem cell (hiPSC)-derived neurons. The system maintained hundreds of parallel neuronal pairs for over 100 days, demonstrating functional synapses through pharmacological validation. We coupled this platform with a biophysical Hodgkin-Huxley model and simulation-based inference to extract mechanistic parameters from the electrophysiological data. As a proof-of-concept application, we analyzed shifts in model parameter distributions following a stimulation protocol. The biophysical model revealed α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) and N-methyl-D-aspartate (NMDA) receptor-specific alterations after stimulation, providing quantitative insights into synaptic plasticity mechanisms. This integrated approach combines isolated hiPSC-derived synaptic pairs, stable parallel long-term recordings, and mechanistic modeling to enable systematic studies of human synaptic transmission.