Advances in high-resolution functional MRI, multimodal imaging, and computational modeling over the past decade have significantly reshaped our understanding of depression. Rather than viewing major depressive disorder as a localized or purely neurochemical condition, it is now increasingly recognized as a disorder of distributed brain network dynamics. Converging evidence points to consistent dysregulation across three large-scale neural systems—collectively known as the “triple network”: the Salience Network (SN), the Central Executive (or Frontoparietal) Network (CEN/FPN), and the Default Mode Network (DMN).