The structural and functional organization of brain networks subserving basic daily activities (i.e. language, visuo-spatial cognition, movement, semantics, etc.) are not completely understood to date. Here, we report the first probabilistic cortical and subcortical atlas of critical structures mediating human brain functions based on direct electrical stimulation (DES), a well-validated tool for the exploration of cerebral processing and for performing safe surgical interventions in eloquent areas. We collected 1162 cortical and 659 subcortical DES responses during testing of 16 functional domains in 256 patients undergoing awake surgery. Spatial coordinates for each functional response were calculated, and probability distributions for the entire patient cohort were mapped onto a standardized three-dimensional brain template using a multinomial statistical analysis. In addition, matching analyses were performed against prior established anatomy-based cortical and white matter (WM) atlases. The probabilistic maps for each functional domain were provided. The topographical analysis demonstrated a wide spatial distribution of cortical functional responses, while subcortical responses were more restricted, localizing to known WM pathways. These DES-derived data showed reliable matching with existing cortical and WM atlases as well as recent neuroimaging and neurophysiological data. We present the first integrated and comprehensive cortical-subcortical atlas of structures essential for humans' neural functions based on highly-specific DES mapping during real-time neuropsychological testing. This novel atlas can serve as a complementary tool for neuroscientists, along with data obtained from other modalities, to improve and refine our understanding of the functional anatomy of critical brain networks.

Background: High-grade gliomas are the most frequently occurring brain tumors and carry unfavorable prognosis. Literature is controversial regarding the effects of surgery on cognitive functions. Methods: We analyzed a homogenous population of 30 patients with high-grade glioma who underwent complete resection. Patients underwent extensive neuropsychological analysis before surgery, 7 days after surgery, and approximately 40 days after surgery, before adjuvant treatments. Thirty-four neuropsychological tests were administered in the language, memory, attention, executive functions, and praxis domains. Results: The preoperative percentage of patients with impairment in the considered tests ranged from 0% to 53.3% (mean 20.9%). Despite a general worsening at early follow-up, a significant recovery was observed at late follow-up. Preoperative performances in language and verbal memory tasks depended on the joint effect of tumor volume, volume of surrounding edema, and tumor localization, with major deficits in patients with left lateralized tumor, especially insular and temporal. Preoperative performances in attention and constructive abilities tasks depended on the joint effect of tumor volume, volume of surrounding edema, and patient age, with major deficits in patients ≥ 65 years old. Recovery at late follow-up depended on the volume of resected tumor, edema resorption, and patient age. Conclusions: Longitudinal neuropsychological performance of patients affected by high-grade glioma depends, among other factors, on the complex interplay of tumor volume, volume of surrounding edema, tumor localization, and patient age. Reported results support the definition of criteria for surgical indication based on the above factors. They may be used to propose more customized surgical, oncological, and rehabilitative strategies.

Even if different dissection, tractographic and connectivity studies provided pure anatomical evidences about the optic radiations (ORs), descriptions of both the anatomical structure and the anatomo‐functional relationships of the ORs with the adjacent bundles were not reported. We propose a detailed anatomical and functional study with ‘post mortem’ dissections and ‘in vivo’ direct electrical stimulation (DES) of the OR, demonstrating also the relationships with the adjacent eloquent bundles in a neurosurgical ‘connectomic’ perspective. Six human hemispheres (three left, three right) were dissected after a modified Klingler's preparation. The anatomy of the white matter was analysed according to systematic and topographical surgical perspectives. The anatomical results were correlated to the functional responses collected during three resections of tumours guided by cortico‐subcortical DES during awake procedures. We identified two groups of fibres forming the OR. The superior component runs along the lateral wall of the occipital horn, the trigone and the supero‐medial wall of the temporal horn. The inferior component covers inferiorly the occipital horn and the trigone, the lateral wall of the temporal horn and arches antero‐medially to form the Meyer's Loop. The inferior fronto‐occipital fascicle (IFOF) covers completely the superior OR along its entire course, as confirmed by the subcortical DES. The inferior longitudinal fascicle runs in a postero‐anterior and inferior direction, covering the superior OR posteriorly and the inferior OR anteriorly. The IFOF identification allows the preservation of the superior OR in the anterior temporal resection, avoiding post‐operative complete hemianopia. The identification of the superior OR during the posterior temporal, inferior parietal and occipital resections leads to the preservation of the IFOF and of the eloquent functions it subserves. The accurate knowledge of the OR course and the relationships with the adjacent bundles is crucial to optimize quality of resection and functional outcome.