We describe microelectrode recording and stimulation techniques to delineate the cellular boundaries and neural projections of stereotactic brain targets. These techniques have applications in the surgery for pain, movement disorders and in psychosurgery. Neuronal records from stereotactic operations including thalamotomy, pallidotomy, cingulotomy and anterior capsulotomy are discussed. These tools are used to distinguish gray matter from white matter, to obtain direct measures of cellular activity in the target, to identify the physiological properties and receptive fields of the subpopulation of neurons at the electrode tip and to avoid lesion making induced injury to adjacent structures. Microelectrode recording and stimulation techniques improve physiological localization and decrease the possibility of unwanted neurological complications with functional stereotactic procedures.