title: Influence of White and Gray Matter Connections on Endogenous Human Cortical Oscillations.
abstract: Brain oscillations reflect changes in electrical potentials summated across neuronal populations. Low- and high-frequency rhythms have different modulation patterns. Slower rhythms are spatially broad, while faster rhythms are more local. From this observation, we hypothesized that low- and high-frequency oscillations reflect white- and gray-matter communications, respectively, and synchronization between low-frequency phase with high-frequency amplitude represents a mechanism enabling distributed brain-networks to coordinate local processing. Testing this common understanding, we selectively disrupted white or gray matter connections to human cortex while recording surface field potentials. Counter to our original hypotheses, we found that cortex consists of independent oscillatory-units (IOUs) that maintain their own complex endogenous rhythm structure. IOUs are differentially modulated by white and gray matter connections. White-matter connections maintain topographical anatomic heterogeneity (i.e., separable processing in cortical space) and gray-matter connections segregate cortical synchronization patterns (i.e., separable temporal processing through phase-power coupling). Modulation of distinct oscillatory modules enables the functional diversity necessary for complex processing in the human brain.
authors.affiliation: Department of Neurological Surgery, Washington University School of Medicine Saint Louis, MO, USA.
authors.forename: Ammar H
authors.initials: AH
authors.lastname: Hawasli
authors.affiliation: Department of Biomedical Engineering, Washington University School of Medicine Saint Louis, MO, USA.
authors.forename: DoHyun
authors.initials: D
authors.lastname: Kim
authors.affiliation: Department of Biomedical Engineering, Washington University School of Medicine Saint Louis, MO, USA.
authors.forename: Noah M
authors.initials: NM
authors.lastname: Ledbetter
authors.affiliation: Department of Pathology and Immunology, Washington University School of Medicine Saint Louis, MO, USA.
authors.forename: Sonika
authors.initials: S
authors.lastname: Dahiya
authors.affiliation: Department of Biomedical Engineering, Washington University School of Medicine Saint Louis, MO, USA.
authors.forename: Dennis L
authors.initials: DL
authors.lastname: Barbour
authors.affiliation: Department of Neurological Surgery, Washington University School of MedicineSaint Louis, MO, USA; Department of Biomedical Engineering, Washington University School of MedicineSaint Louis, MO, USA.
authors.forename: Eric C
authors.initials: EC
authors.lastname: Leuthardt
keywords: cortical oscillations; cortical physiology; electrocorticography; human neuroscience; neurophysiology