title: Multimodal responses induced by cortical stimulation of the parietal lobe: a stereo-electroencephalography study.
abstract: The functional complexity of the parietal lobe still represents a challenge for neurophysiological and functional neuroimaging studies. While the somatosensory functions of the anterior parietal cortex are well established, the posterior parietal cortex has a relevant role in processing the sensory information, including visuo-spatial perception, visual attention, visuo-motor transformations and other complex and not completely understood functions. We retrospectively analysed all the clinical manifestations induced by intracerebral bipolar electrical stimulation in 172 patients suffering from drug-resistant focal epilepsy (mean age 25.6, standard deviation 11.6; 44% females and 56% males) with at least one electrode stereotactically implanted in the parietal cortex. A total of 1186 electrical stimulations were included in the analysis, of which 88 were subsequently excluded because of eliciting pathological electric activity or inducing ictal symptomatology. In the dominant parietal lobe, clinical responses were observed for 56 (25%) of the low-frequency stimulations and for 76 (50%) of the high-frequency stimulations. In the non-dominant parietal lobe, 111 (27%) low-frequency and 176 (55%) high-frequency stimulations were associated with a clinical response. Body scheme alteration was the only clinical effect showing a lateralization, as they were evoked only in the non-dominant hemisphere. The occurrence of somatosensory sensations, motor symptoms, dysarthria and multimodal responses were significantly associated with stimulation of the postcentral gyrus (odds ratio: 5.83, P < 0.001; odds ratio: 8.77, P < 0.001; odds ratio: 5.44, P = 0.011; odds ratio: 8.33, P = 0.006; respectively). Stimulation of the intraparietal sulcus was associated with the occurrence of sensory illusions or hallucinations (odds ratio: 8.68, P < 0.001) and eyeball/eyelid movements or sensations (odds ratio: 4.35, P = 0.047). To our knowledge, this is the only currently available complete revision of electrical stimulation of the entire parietal cortex with the aim to evaluate the neurophysiology of this relevant brain region. Our analysis offers a general overview of the multiple roles of the parietal cortex and supports its crucial involvement in different networks related to complex integrative functions.media-1vid110.1093/brain/awv187_video_abstractawv187_video_abstract.
authors.affiliation: 1 Neurological Clinic, Department of Experimental and Clinical Medicine, Marche Polytechnic University, Ancona, Italy s.balestrini@ucl.ac.uk.
authors.forename: Simona
authors.initials: S
authors.lastname: Balestrini
authors.affiliation: 2 'Claudio Munari' Epilepsy Surgery Centre, Niguarda Hospital, Milan, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Francione
authors.affiliation: 2 'Claudio Munari' Epilepsy Surgery Centre, Niguarda Hospital, Milan, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Mai
authors.affiliation: 2 'Claudio Munari' Epilepsy Surgery Centre, Niguarda Hospital, Milan, Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Castana
authors.affiliation: 2 'Claudio Munari' Epilepsy Surgery Centre, Niguarda Hospital, Milan, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Casaceli
authors.affiliation: 3 Department of Neurological and Sensorial Sciences, University of Siena, Italy.
authors.forename: Daniela
authors.initials: D
authors.lastname: Marino
authors.affiliation: 1 Neurological Clinic, Department of Experimental and Clinical Medicine, Marche Polytechnic University, Ancona, Italy.
authors.forename: Leandro
authors.initials: L
authors.lastname: Provinciali
authors.affiliation: 2 'Claudio Munari' Epilepsy Surgery Centre, Niguarda Hospital, Milan, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Cardinale
authors.affiliation: 2 'Claudio Munari' Epilepsy Surgery Centre, Niguarda Hospital, Milan, Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Tassi
mesh_terms: D000293:Adolescent; D000328:Adult; D001931:Brain Mapping; D046690:Deep Brain Stimulation / Q000379:methods*; D004567:Electrodes, Implanted; D004569:Electroencephalography; D004828:Epilepsies, Partial / Q000628:therapy*; D005260:Female; D007839:Functional Laterality; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D010296:Parietal Lobe / Q000502:physiology*; D012189:Retrospective Studies; D013238:Stereotaxic Techniques; D055815:Young Adult
keywords: associational areas; clinical neurophysiology; parietal lobe; sensory systems; stereo-EEG