Adaptive Network Stabilization Despite Profound Structural Reorganization in Human Organotypic Cultures.

Human organotypic slice cultures provide experimental access to adult human neuronal circuits ex vivo, yet it remains unclear whether these networks preserve function or undergo fundamental reorganization following the profound perturbation of slice preparation. Here, a multimodal approach combines extracellular electrophysiology, longitudinal calcium imaging, and quantitative histology to track the changes of human cortical slice cultures over several weeks in vitro. Early phases are marked by pronounced variability and instability, with reduced firing rates, increased burst propensity in principal cells, and heterogeneous recruitment during population activity. These functional changes coincide with substantial structural remodeling, including considerable neuronal loss, disruption of laminar architecture, reactive gliosis, and selective vulnerability of inhibitory interneurons. Despite this structural degradation, neuronal activity converges: electrophysiological properties, cell-type-specific firing patterns, and population-event recruitment become stable and highly consistent. Calcium imaging reveals the progressive evolution of spatially confined active regions, indicating the stabilization of structured network dynamics. These findings demonstrate a remarkable capacity of adult human neuronal circuits for functional adaptation, transitioning from heterogeneous, injury-driven dynamics to stable and reproducible neuronal activity. This dissociation between anatomical deterioration and functional stabilization should be considered when using organotypic slice cultures as a platform for studying human physiological or pathological brain network dynamics.