This study reports that terahertz radiation decreased a neuronal membrane area ratio (cytosol relative to protruding membrane area) beginning on the first day of exposure and persisting during the exposure period. It further reports altered neuronal firing/discharge patterns and increased peak postsynaptic currents associated with the morphology change, supported by a kinetic model. The authors frame the findings as indicating significant effects of terahertz-frequency EMF on neural health and function and suggest potential neuromodulation applications.