This chapter examines intraoperative neurophysiological monitoring (IONM) advancements and brain mapping techniques for supratentorial glioma surgeries. It focuses on balancing complete tumour resection with preserving essential neurological functions to maintain patients’ quality of life. The shift from traditional localisationist views to hodology and inter-network connectivity witness the evolution of a more sophisticated approach to the brain’s dynamic. Fundamental IONM techniques include motor-evoked potentials (MEPs) and somatosensory-evoked potentials (SSEPs). These techniques ensure accurate monitoring and help prevent neurological injuries. On the contrary, advanced brain mapping techniques-using direct electrical stimulation (DES)-can guide surgeons in identifying critical cortical and subcortical structures to be preserved. This chapter compares low-frequency (LF) DES with the high-frequency (HF) paradigm and their relative parameters optimisation to fit cortical and subcortical mapping in different scenarios. It provides examples of applications and the principles behind stimulation parameter tuning. Integrating these neurophysiological techniques into surgical practice enhances the safety and efficacy of tumour resections. Real-time feedback on neural pathway integrity aids surgeons in navigating brain complexities, allowing maximal tumour removal with minimal functional impairment. This chapter provides a comprehensive overview of IONM and brain mapping advancements, emphasising their crucial role in improving neurosurgical outcomes for patients with supratentorial gliomas.