The brain mechanisms of self-identification & self-location in neurosurgical patients using virtual reality and lesion network mapping
Authors: Betka Sophie , Haemmerli Julien , Park Hyeong-Dong , Iannotti Giannina Rita , Orepic Pavo , Blondiaux Eva , Alcoba-Banqueri Sixto , Herbelin Bruno , Michel Christoph M. , Blanke Olaf , Schaller Karl 
Published: March 2022

AbstractBackground and ObjectivesThe identification of cognitive biomarkers in preoperative counselling and their monitoring during brain surgery is of growing interest for the safe conduction of resective intracranial procedures with potential impact on the patients’ personality. The conscious experience of identifying with the body (self-identification) and of where ‘I’ am in space(self-location) are central for bodily self-consciousness (BSC). In a virtual reality (VR) paradigm using multisensory feedback, illusory self-identification and self-location over a virtual body can be induced, by manipulating the synchrony of visuo-tactile inputs. To date, no studies applied lesion network mapping (LNM) to investigate networks underlying BSC components with VR.MethodsFifteen neurosurgical patients with intra-axial and extra-axial brain lesions(8 pre-resection, 9 post-resection) performed the visuo-tactile VR paradigm. Patients subjectively rated their self-identification and self-location, after being exposed to synchronous or asynchronous visuo-tactile stimulations. We applied LNM analysis using functional data from 1015 healthy subjects and determined functional connectivity patterns related to each measure.ResultsIn the post-surgery group, theself-identification networkincluded the right inferior frontal, superior frontal and inferior temporal gyri. Theself-location networkencompassed the right parahippocampal gyrus, superior temporal gyrus, bilateral cerebellum and brainstem. No clusters survived for the pre-surgery group.DiscussionOur LNM findings reveal the existence of two distinct networks for self-identification and self-location, including structures playing key roles in self-recognition or self-other distinction as well as in spatial navigation or memory processes, respectively. Such networks should be added to the portfolio of presurgical surveillance of functions related to the sense of self to improve future surgical outcomes.What is already known on this topicThe development of extra- and intraoperative cognitive biomarkers is of importance for monitoring the personality of patients during cranial surgical procedures, as that may allow for individualized pre-operative counselling and intraoperative decision making. Such guidance may ultimately help to improve neuropsychological outcomes following brain surgery.Bodily self-consciousness refers to a perceptual form of the sense of self, related to multisensory bodily inputs, which can be disrupted in neurological, psychiatric, or neurosurgical conditions.What this study addsIn this study, we investigated networks associated with changes in two components bodily self-consciousness (self-identification, self-location) that we manipulated in real-time using multisensory stimulation and virtual reality in neurosurgical patients, who underwent resective surgery for brain tumors or lesions (gliomas, meningiomas, epileptic foci).Our lesion network mapping findings reveal the existence of two distinct networks of bodily self-consciousness, including structures playing key roles in self-recognition or self-other distinction for self-identification, and in spatial navigation or memory processes for self-location.How this study might affect research, practice or policyIdeally, such networks should be identified, and their individual anatomical allocation be integrated in the surgical plan, to make them potentially amenable for functional mapping and monitoring during resective brain surgery. Ultimately, that assessment of functions related to the sense of self and personality should help.