title: Detecting Functional Connectivity During Audiovisual Integration with MEG: A Comparison of Connectivity Metrics.
abstract: In typical magnetoencephalography and/or electroencephalography functional connectivity analysis, researchers select one of several methods that measure a relationship between regions to determine connectivity, such as coherence, power correlations, and others. However, it is largely unknown if some are more suited than others for various types of investigations. In this study, the authors investigate seven connectivity metrics to evaluate which, if any, are sensitive to audiovisual integration by contrasting connectivity when tracking an audiovisual object versus connectivity when tracking a visual object uncorrelated with the auditory stimulus. The authors are able to assess the metrics' performances at detecting audiovisual integration by investigating connectivity between auditory and visual areas. Critically, the authors perform their investigation on a whole-cortex all-to-all mapping, avoiding confounds introduced in seed selection. The authors find that amplitude-based connectivity measures in the beta band detect strong connections between visual and auditory areas during audiovisual integration, specifically between V4/V5 and auditory cortices in the right hemisphere. Conversely, phase-based connectivity measures in the beta band as well as phase and power measures in alpha, gamma, and theta do not show connectivity between audiovisual areas. The authors postulate that while beta power correlations detect audiovisual integration in the current experimental context, it may not always be the best measure to detect connectivity. Instead, it is likely that the brain utilizes a variety of mechanisms in neuronal communication that may produce differential types of temporal relationships.
authors.affiliation: 1 Magnetoencephalography Core Facility, National Institute of Mental Health (NIMH) , National Institutes of Health, Bethesda, Maryland.|2 Neuroscience Graduate Program, Brown University , Providence, Rhode Island.
authors.forename: Tyler
authors.initials: T
authors.lastname: Ard
authors.affiliation: 1 Magnetoencephalography Core Facility, National Institute of Mental Health (NIMH) , National Institutes of Health, Bethesda, Maryland.
authors.forename: Frederick W
authors.initials: FW
authors.lastname: Carver
authors.affiliation: 1 Magnetoencephalography Core Facility, National Institute of Mental Health (NIMH) , National Institutes of Health, Bethesda, Maryland.
authors.forename: Tom
authors.initials: T
authors.lastname: Holroyd
authors.affiliation: 3 Brain Imaging and Modeling Section, Voice, Speech, and Language Branch, National Institute on Deafness and Other Communication Disorders (NIDCD), National Institutes of Health , Bethesda, Maryland.
authors.forename: Barry
authors.initials: B
authors.lastname: Horwitz
authors.affiliation: 1 Magnetoencephalography Core Facility, National Institute of Mental Health (NIMH) , National Institutes of Health, Bethesda, Maryland.
authors.forename: Richard
authors.initials: R
authors.lastname: Coppola
mesh_terms: D000161:Acoustic Stimulation / Q000379:methods; D000328:Adult; D001307:Auditory Perception / Q000502:physiology*; D001921:Brain / Q000502:physiology*; D001931:Brain Mapping / Q000379:methods; D005260:Female; D006801:Humans; D015225:Magnetoencephalography; D008297:Male; D008875:Middle Aged; D009434:Neural Pathways / Q000502:physiology; D010775:Photic Stimulation / Q000379:methods; D014796:Visual Perception / Q000502:physiology*; D055815:Young Adult
keywords: MEG; all-to-all; audiovisual integration; beta; coherence; functional connectivity; multimodal; oscillation