Measuring the Electrophysiological Effects of Direct Electrical Brain Stimulation during Awake Surgery of Low Grade Glioma

The "Awake brain surgery" consists in removing some infiltrative and slow-growing brain tumor tissues in an awake patient. The neurosurgeon performs an anatomo-functional mapping of the brain by electrically stimulating brain areas near the tumor to discriminate functional versus nonfunctional areas. This stimulation is both made cortically and subcortically to preserve the anatomical connectivity on-line. During the surgery itself, the patient is involved by performing some behavioral tasks of interest (intra-operative assessments). Despite marked functional deficits after the surgery the recovery of these patients remains impressive with respect to the lesion volume. These observations question our understanding of brain dynamics and plasticity phenomena. The electrical stimulation procedure associated to the intra-operative assessments are thus critical aspects that need to be optimized in order to improve the precision of the anatomo-functional mapping of the brain and to better understand its dynamics and plasticity for these patients. More specifically, this multidisciplinary project aims at better understanding the electrophysiological effects of the direct electrical stimulation during the surgery using intra-operative electroencephalographic and electrocorticographic recordings. A method to detect off-line remote electrophysiological effects and neuromodulations due to the application of electrical stimulation will be developped for further on-line applications during the surgery, in order to optimize electrical stimulations and improve the anatomo-functional brain mapping. By more systematically performing these precise measurements during the surgery we hope to better understand brain dynamics and plasticity in order to improve the surgical planning, rehabilitation, and quality of life of the patients.