This chapter explores the neurophysiological mapping techniques used in surgeries targeting lesions near or within areas of eloquent cortex, where the risk of postoperative neurological deficits is high. The primary objective of these surgeries is to achieve a maximal resection of the lesion while preserving neurological function to maintain or improve the patient’s quality of life. Traditional imaging and microscopic technologies often lack the resolution needed to distinguish between normal and pathological tissues, especially in distorted anatomy. Therefore, neurophysiological methods, such as the phase reversal technique (PRT) and direct cortical or subcortical stimulation (DCS/SCS), have proven effective for intraoperative localization of perirolandic gyri. These techniques allow for accurate localization of the central sulcus, identification of functional brain tissue, and optimization of parameters for continuous monitoring. This chapter provides a comprehensive overview of these neurophysiological modalities, emphasizing their role in maximizing lesion resection while safeguarding sensory and motor pathways.