Neuroplasticity mapping methods. Illustrated in panels (a)–(d) are various brain mapping techniques performed on a 30-year-old right-handed male with low-grade glioma intraoperatively (a) and prior to surgery ((b)–(d)). The approximate tumor border is shown (red dash) in panels (b)–(d). (a) Postresection intraoperative photograph of functional sites elicited by direct electrical stimulation: tags B/C lip movement (yellow); tags E/F tongue movement (green); tag K speech difficulty (orange). Note the close correlation between cortical language (orange), lip motor (yellow), and tongue motor (green) sites obtained by fMRI (panel (b)). Other tags shown denote face motor sites. At the inferior/posterior border of the resection cavity, stimulation of the IFOF (gray asterisk) caused speech disturbance. (b) Functional MRI (fMRI) demonstrating language activation (green) at the junction of pars opercularis and precentral gyrus and lip (yellow) and tongue (green) motor activation in the inferior precentral gyrus. (c) Diffusion tensor imaging (DTI) demonstrating two major white matter bundles in close proximity to the tumor: the inferior frontal occipital fasciculus (IFOF, green) that transmits semantic language information and the corticospinal tract (CST, blue) which conveys descending primary motor information. (d) MRI-navigated transcranial magnetic stimulation (TMS) of the hand motor area of the precentral gyrus elicited overt muscle contraction.