title: Corticocortical evoked potentials reveal projectors and integrators in human brain networks.
abstract: The cerebral cortex is composed of subregions whose functional specialization is largely determined by their incoming and outgoing connections with each other. In the present study, we asked which cortical regions can exert the greatest influence over other regions and the cortical network as a whole. Previous research on this question has relied on coarse anatomy (mapping large fiber pathways) or functional connectivity (mapping inter-regional statistical dependencies in ongoing activity). Here we combined direct electrical stimulation with recordings from the cortical surface to provide a novel insight into directed, inter-regional influence within the cerebral cortex of awake humans. These networks of directed interaction were reproducible across strength thresholds and across subjects. Directed network properties included (1) a decrease in the reciprocity of connections with distance; (2) major projector nodes (sources of influence) were found in peri-Rolandic cortex and posterior, basal and polar regions of the temporal lobe; and (3) major receiver nodes (receivers of influence) were found in anterolateral frontal, superior parietal, and superior temporal regions. Connectivity maps derived from electrical stimulation and from resting electrocorticography (ECoG) correlations showed similar spatial distributions for the same source node. However, higher-level network topology analysis revealed differences between electrical stimulation and ECoG that were partially related to the reciprocity of connections. Together, these findings inform our understanding of large-scale corticocortical influence as well as the interpretation of functional connectivity networks.
authors.affiliation: Department of Neurosurgery, Hofstra North Shore LIJ School of Medicine, and Feinstein Institute for Medical Research, Manhasset, New York 11030, Departments of Neuroscience and.
authors.forename: Corey J
authors.initials: CJ
authors.lastname: Keller
authors.affiliation: Department of Psychology, University of Toronto, Toronto, M5S 3G3, Ontario, Canada, and.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Honey
authors.affiliation: Institute of Cognitive Neuroscience and Psychology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, 1132 Budapest, Hungary, National Institute of Clinical Neuroscience, 1145 Budapest, Hungary, Péter Pázmány Catholic University, Faculty of Information Technology and Bionics, 1088 Budapest, Hungary.
authors.forename: Laszlo
authors.initials: L
authors.lastname: Entz
authors.affiliation: Department of Neurosurgery, Hofstra North Shore LIJ School of Medicine, and Feinstein Institute for Medical Research, Manhasset, New York 11030, Neurology, Albert Einstein College of Medicine, Bronx, New York 10461.
authors.forename: Stephan
authors.initials: S
authors.lastname: Bickel
authors.affiliation: Department of Neurosurgery, Hofstra North Shore LIJ School of Medicine, and Feinstein Institute for Medical Research, Manhasset, New York 11030.
authors.forename: David M
authors.initials: DM
authors.lastname: Groppe
authors.affiliation: Péter Pázmány Catholic University, Faculty of Information Technology and Bionics, 1088 Budapest, Hungary.
authors.forename: Emilia
authors.initials: E
authors.lastname: Toth
authors.affiliation: Institute of Cognitive Neuroscience and Psychology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, 1132 Budapest, Hungary, Péter Pázmány Catholic University, Faculty of Information Technology and Bionics, 1088 Budapest, Hungary.
authors.forename: Istvan
authors.initials: I
authors.lastname: Ulbert
authors.affiliation: Departments of Neuroscience and Neurology, Albert Einstein College of Medicine, Bronx, New York 10461, Department of Neurology, Montefiore Medical Center, Bronx, New York 10467.
authors.forename: Fred A
authors.identifier: http://orcid.org/0000-0003-3648-4812
authors.initials: FA
authors.lastname: Lado
authors.affiliation: Department of Neurosurgery, Hofstra North Shore LIJ School of Medicine, and Feinstein Institute for Medical Research, Manhasset, New York 11030, amehta@nshs.edu.
authors.forename: Ashesh D
authors.initials: AD
authors.lastname: Mehta
mesh_terms: D000293:Adolescent; D000328:Adult; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000502:physiology*; D004558:Electric Stimulation; D004567:Electrodes, Implanted; D005071:Evoked Potentials / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009434:Neural Pathways / Q000502:physiology*; D015203:Reproducibility of Results; D016037:Single-Blind Method; D055815:Young Adult
keywords: ECoG; effective connectivity; functional connectivity; graph theory; stimulation