title: Independent Component Decomposition of Human Somatosensory Evoked Potentials Recorded by Micro-Electrocorticography.
abstract: High-density surface microelectrodes for electrocorticography (ECoG) have become more common in recent years for recording electrical signals from the cortex. With an acceptable invasiveness/signal fidelity trade-off and high spatial resolution, micro-ECoG is a promising tool to resolve fine task-related spatial-temporal dynamics. However, volume conduction - not a negligible phenomenon - is likely to frustrate efforts to obtain reliable and resolved signals from a sub-millimeter electrode array. To address this issue, we performed an independent component analysis (ICA) on micro-ECoG recordings of somatosensory-evoked potentials (SEPs) elicited by median nerve stimulation in three human patients undergoing brain surgery for tumor resection. Using well-described cortical responses in SEPs, we were able to validate our results showing that the array could segregate different functional units possessing unique, highly localized spatial distributions. The representation of signals through the root-mean-square (rms) maps and the signal-to-noise ratio (SNR) analysis emphasizes the advantages of adopting a source analysis approach on micro-ECoG recordings in order to obtain a clear picture of cortical activity. The implications are twofold: while on one side ICA may be used as a spatial-temporal filter extracting micro-signal components relevant to tasks for brain-computer interface (BCI) applications, it could also be adopted to accurately identify the sites of nonfunctional regions for clinical purposes.
authors.affiliation: 1 Center for Translational Neurophysiology IIT@Unife, Istituto Italiano di Tecnologia, Via Fossato di Mortara 17-19, 44121 Ferrara, Italy.
authors.forename: Irene
authors.initials: I
authors.lastname: Rembado
authors.affiliation: 1 Center for Translational Neurophysiology IIT@Unife, Istituto Italiano di Tecnologia, Via Fossato di Mortara 17-19, 44121 Ferrara, Italy.
authors.forename: Elisa
authors.initials: E
authors.lastname: Castagnola
authors.affiliation: 2 University of Trento, Center for Mind/Brain Sciences (CIMeC), Via delle Regole, 101, 38123 Trento, Italy.
authors.forename: Luca
authors.initials: L
authors.lastname: Turella
authors.affiliation: 3 Struttura complessa di Neurochirurgia, Azienda Ospedaliero-Universitaria Santa Maria della Misericordia, Piazzale Santa Maria della Misericordia 15, 33100 Udine, Italy.
authors.forename: Tamara
authors.initials: T
authors.lastname: Ius
authors.affiliation: 3 Struttura complessa di Neurochirurgia, Azienda Ospedaliero-Universitaria Santa Maria della Misericordia, Piazzale Santa Maria della Misericordia 15, 33100 Udine, Italy.
authors.forename: Riccardo
authors.initials: R
authors.lastname: Budai
authors.affiliation: 4 Graphene Labs, Istituto Italiano di Tecnologia, via Morego 30, 16163 Genova, Italy.
authors.forename: Alberto
authors.initials: A
authors.lastname: Ansaldo
authors.affiliation: 5 Neuroscience and Brain Technologies Department, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy.
authors.forename: Gian Nicola
authors.initials: GN
authors.lastname: Angotzi
authors.affiliation: 6 Department of Neurosciences and Mental Health, Psychiatric Clinic, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, University of Milan, Milan, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Debertoldi
authors.affiliation: 1 Center for Translational Neurophysiology IIT@Unife, Istituto Italiano di Tecnologia, Via Fossato di Mortara 17-19, 44121 Ferrara, Italy.
authors.forename: Davide
authors.initials: D
authors.lastname: Ricci
authors.affiliation: 3 Struttura complessa di Neurochirurgia, Azienda Ospedaliero-Universitaria Santa Maria della Misericordia, Piazzale Santa Maria della Misericordia 15, 33100 Udine, Italy.
authors.forename: Miran
authors.initials: M
authors.lastname: Skrap
authors.affiliation: 1 Center for Translational Neurophysiology IIT@Unife, Istituto Italiano di Tecnologia, Via Fossato di Mortara 17-19, 44121 Ferrara, Italy.|7 Section of Human Physiology, University of Ferrara, Via Fossato di Mortara 17-19, 44121 Ferrara, Italy.
authors.forename: Luciano
authors.initials: L
authors.lastname: Fadiga
mesh_terms: D000328:Adult; D001932:Brain Neoplasms / Q000503:physiopathology / Q000601:surgery; D004558:Electric Stimulation; D000069280:Electrocorticography / Q000295:instrumentation / Q000379:methods*; D004867:Equipment Design; D005073:Evoked Potentials, Somatosensory; D005910:Glioma / Q000503:physiopathology / Q000601:surgery; D006801:Humans; D008297:Male; D008475:Median Nerve / Q000503:physiopathology; D008839:Microelectrodes; D008875:Middle Aged; D009044:Motor Cortex / Q000503:physiopathology; D012815:Signal Processing, Computer-Assisted; D013003:Somatosensory Cortex / Q000503:physiopathology; D055698:Touch Perception / Q000502:physiology
keywords: BCI; ICA; Micro-ECoG; SEP