MBP and neoplasm: Using ex vivo resected tissue from patients undergoing tumor surgery, we performed whole-cell electrophysiological recordings (Supplementary file 3) and intracellular biocytin labeling with post hoc MBP immunofluorescence of fast-spiking interneurons classified on the basis of morphology and electrophysiology (Figure 9a–e; 4 cells from four donors; see Materials and methods).