title: Alterations of Intrinsic Brain Connectivity Patterns in Depression and Bipolar Disorders: A Critical Assessment of Magnetoencephalography-Based Evidence.
abstract: Despite being the object of a thriving field of clinical research, the investigation of intrinsic brain network alterations in psychiatric illnesses is still in its early days. Because the pathological alterations are predominantly probed using functional magnetic resonance imaging (fMRI), many questions about the electrophysiological bases of resting-state alterations in psychiatric disorders, particularly among mood disorder patients, remain unanswered. Alongside important research using electroencephalography (EEG), the specific recent contributions and future promise of magnetoencephalography (MEG) in this field are not fully recognized and valued. Here, we provide a critical review of recent findings from MEG resting-state connectivity within major depressive disorder (MDD) and bipolar disorder (BD). The clinical MEG resting-state results are compared with those previously reported with fMRI and EEG. Taken together, MEG appears to be a promising but still critically underexploited technique to unravel the neurophysiological mechanisms that mediate abnormal (both hyper- and hypo-) connectivity patterns involved in MDD and BD. In particular, a major strength of MEG is its ability to provide source-space estimations of neuromagnetic long-range rhythmic synchronization at various frequencies (i.e., oscillatory coupling). The reviewed literature highlights the relevance of probing local and interregional rhythmic synchronization to explore the pathophysiological underpinnings of each disorder. However, before we can fully take advantage of MEG connectivity analyses in psychiatry, several limitations inherent to MEG connectivity analyses need to be understood and taken into account. Thus, we also discuss current methodological challenges and outline paths for future research. MEG resting-state studies provide an important window onto perturbed spontaneous oscillatory brain networks and hence supply an important complement to fMRI-based resting-state measurements in psychiatric populations.
authors.affiliation: Department of Psychology, University of Montreal , Montreal, QC , Canada.
authors.forename: Golnoush
authors.initials: G
authors.lastname: Alamian
authors.affiliation: Department of Psychology, University of Montreal, Montreal, QC, Canada; Department of Computer Science, Pontificia Universidad Católica de Chile, Santiago de Chile, Chile; Interdisciplinary Center for Neurosciences, School of Psychology, Pontificia Universidad Católica de Chile, Santiago de Chile, Chile.
authors.forename: Ana-Sofía
authors.initials: AS
authors.lastname: Hincapié
authors.affiliation: Department of Psychology, University of Montreal, Montreal, QC, Canada; Center of Research and Innovation in Sport, Mental Processes and Motor Performance, University Claude Bernard Lyon I, University of Lyon, Villeurbanne, France; Brain Dynamics and Cognition, Lyon Neuroscience Research Center, INSERM U1028, UMR 5292, University of Lyon, Villeurbanne, France.
authors.forename: Etienne
authors.initials: E
authors.lastname: Combrisson
authors.affiliation: Department of Psychology, University of Montreal , Montreal, QC , Canada.
authors.forename: Thomas
authors.initials: T
authors.lastname: Thiery
authors.affiliation: Department of Psychology, University of Montreal , Montreal, QC , Canada.
authors.forename: Véronique
authors.initials: V
authors.lastname: Martel
authors.affiliation: Department of Psychology, University of Montreal, Montreal, QC, Canada; Department of Computer Sciences, National Research Institution Higher School of Economics, Moscow, Russia; MEG Center, Moscow State University of Pedagogics and Education, Moscow, Russia.
authors.forename: Dmitrii
authors.initials: D
authors.lastname: Althukov
authors.affiliation: Department of Psychology, University of Montreal, Montreal, QC, Canada; Centre de recherche de l'Institut universitaire en santé mentale de Montréal, Montreal, QC, Canada.
authors.forename: Karim
authors.initials: K
authors.lastname: Jerbi
keywords: bipolar disorder; connectivity; depression; magnetoencephalography; mental illness; oscillations; psychiatry; resting-state