BPS2026 - Neuronal spiking activity in iPSC-derived human forebrain neurons under space-related static magnetic field alterations

Static magnetic fields (SMFs) are known to impact neuronal activity, yet their impact under space-relevant conditions remains poorly understood. On Earth, the geomagnetic field ranges from 25–65 μT, but in lunar and deep-space environments, the field is nearly absent (∼0 μT). Astronauts frequently report mood disturbances, fatigue, and cognitive impairments following long-duration spaceflight. While microgravity, radiation, and social isolation are known contributors, the specific role of changes in magnetic field exposure has not been systematically examined. In particular, the neural impact of magnetic field removal and reapplication—conditions that mimic the transition from Earth to space and back—remains unexplored. To address this gap, we investigated how SMFs affect neuronal excitability in human iPSC-derived forebrain neurons. Neural progenitor cells were plated on poly-L-ornithine/laminin-coated microelectrode arrays (MEAs, 60MEA100/10iR-ITO), and differentiated into forebrain neurons. Neurons were maintained for three days under Earth-like SMFs (baseline), then subjected to three days without SMF (spaceflight condition), followed by three days of SMF reapplication (return-to-Earth condition). Extracellular signals were recorded at 25 kHz using the multi-channel systems analyzer and processed with a matched filter signal processing approach in MATLAB to quantify spiking activity. Our results reveal that the removal of an SMF increased average spike activity in forebrain neurons compared to the baseline. Notably, reapplication of the SMF restored spiking activity to baseline levels, suggesting that neuronal networks are sensitive to magnetic field transitions but can reset upon re-exposure. These findings demonstrate that human neurons respond dynamically to space-relevant SMF alterations. More broadly, this work highlights the effects of SNFs as an environmental factor that could contribute to alterations in neurocognitive function during long-duration space missions. This work was partially funded by the US NSF (#2349091) and NASA EPSCORE R3 (#24-2024 R3-0114, RFA071).