EMERGENT POPULATION DYNAMICS AND SYNCHRONIZATION IN CORTICAL NETWORKS UNDER WEAK ELECTRIC FIELDS

Optimizing transcranial electrical stimulation (tES) for safety and efficacy remains constrained by an incomplete understanding of how subthreshold fields modulate neural population activity. In particular, how techniques such as transcranial alternating current stimulation (tACS) impact cortical circuit and network-scale dynamics—as opposed to single-cell responses—remains unclear[1,2]. Here, we characterize emergent network dynamic responses to electrical stimulation in a biophysically-detailed rat cortex model[3] across a range of exposure conditions, quantifying phase-synchronized modulation of population activity. Population firing rates exhibited synchronization at the stimulation frequency, with the strength and phase of synchronization dependent on stimulation amplitude and frequency. The network reproduced experimentally observed stimulation onset effects and subsequent adaptation. Synchronization varied across cell populations, indicating differential sensitivity to electric fields: pyramidal cells showed instantaneous strong synchronization to the stimulus frequency, while inhibitory interneurons synchronized more slowly and with distinct phase delays, suggesting down-stream entrainment. To bridge these spiking network dynamics to whole-brain modeling, we fit neural mass models (NMMs) to reproduce the observed responses. The fitted NMMs captured key features of the network dynamics, including stimulus frequency locking. These results advance mesoscale understanding of tES mechanisms and provide a framework for modeling network-level stimulus coupling.

References

1. Aberra et al. 2018 DOI: 10.1088/1741-2552/aadbb1

2. Ruffini et al. 2013 DOI: 10.1109/TNSRE.2012.2200046

3. Isbister et al. 2026 DOI: 10.7554/eLife.99693.3