title: Semi-Automatic Segmentation of Optic Radiations and LGN, and Their Relationship to EEG Alpha Waves.
abstract: At rest, healthy human brain activity is characterized by large electroencephalography (EEG) fluctuations in the 8-13 Hz range, commonly referred to as the alpha band. Although it is well known that EEG alpha activity varies across individuals, few studies have investigated how this may be related to underlying morphological variations in brain structure. Specifically, it is generally believed that the lateral geniculate nucleus (LGN) and its efferent fibres (optic radiation, OR) play a key role in alpha activity, yet it is unclear whether their shape or size variations contribute to its inter-subject variability. Given the widespread use of EEG alpha in basic and clinical research, addressing this is important, though difficult given the problems associated with reliably segmenting the LGN and OR. For this, we employed a multi-modal approach and combined diffusion magnetic resonance imaging (dMRI), functional magnetic resonance imaging (fMRI) and EEG in 20 healthy subjects to measure structure and function, respectively. For the former, we developed a new, semi-automated approach for segmenting the OR and LGN, from which we extracted several structural metrics such as volume, position and diffusivity. Although these measures corresponded well with known morphology based on previous post-mortem studies, we nonetheless found that their inter-subject variability was not significantly correlated to alpha power or peak frequency (p >0.05). Our results therefore suggest that alpha variability may be mediated by an alternative structural source and our proposed methodology may in general help in better understanding the influence of anatomy on function such as measured by EEG or fMRI.
authors.affiliation: Department of Nuclear Medecine and Radiobiology, Faculty of Medicine and Health Science, University of Sherbrooke, Sherbrooke, Qc, Canada.
authors.forename: Emmanuelle
authors.identifier: http://orcid.org/0000-0003-1292-5097
authors.initials: E
authors.lastname: Renauld
authors.affiliation: Sherbrooke Connectivity Imaging Lab (SCIL), Computer Science Department, Faculty of Science, University of Sherbrooke, Sherbrooke, Qc, Canada.|Centre Hospitalier Universitaire de Sherbrooke (CHUS), Sherbrooke, Qc, Canada.|Centre d'Imagerie Moléculaire de Sherbrooke (CIMS), Centre de Recherche du CHUS, Sherbrooke, Qc, Canada.
authors.forename: Maxime
authors.initials: M
authors.lastname: Descoteaux
authors.affiliation: Department of Nuclear Medecine and Radiobiology, Faculty of Medicine and Health Science, University of Sherbrooke, Sherbrooke, Qc, Canada.
authors.forename: Michaël
authors.initials: M
authors.lastname: Bernier
authors.affiliation: Sherbrooke Connectivity Imaging Lab (SCIL), Computer Science Department, Faculty of Science, University of Sherbrooke, Sherbrooke, Qc, Canada.
authors.forename: Eleftherios
authors.initials: E
authors.lastname: Garyfallidis
authors.affiliation: Department of Nuclear Medecine and Radiobiology, Faculty of Medicine and Health Science, University of Sherbrooke, Sherbrooke, Qc, Canada.|Department of Diagnostic Radiology, Faculty of Medicine and Health Science, University of Sherbrooke, Sherbrooke, Qc, Canada.|Centre Hospitalier Universitaire de Sherbrooke (CHUS), Sherbrooke, Qc, Canada.|Centre d'Imagerie Moléculaire de Sherbrooke (CIMS), Centre de Recherche du CHUS, Sherbrooke, Qc, Canada.
authors.forename: Kevin
authors.initials: K
authors.lastname: Whittingstall
mesh_terms: D001931:Brain Mapping / Q000379:methods; D038524:Diffusion Magnetic Resonance Imaging; D004569:Electroencephalography; D005260:Female; D005829:Geniculate Bodies / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D064368:Healthy Volunteers; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009412:Nerve Fibers; D010363:Pattern Recognition, Automated; D015203:Reproducibility of Results; D012146:Rest; D013788:Thalamus / Q000033:anatomy & histology / Q000000981:diagnostic imaging