title: Specific functional asymmetries of the human visual cortex revealed by functional near-infrared spectroscopy.
abstract: Based on multiple invasive reports and neuroimaging studies, it is well established that the cytoarchitecture of the visual cortex is related to its functional organization, namely, its retinotopy. The present study aimed to further investigate retinotopic mapping as well as specific vertical and horizontal functional asymmetries within the human visual cortex using functional near-infrared spectroscopy (fNIRS). Black and white wedge checkerboard stimuli were randomly presented to the four visual field (VF) quadrants of eight healthy adults in order to quantify and compare the localization and the amplitude of hemodynamic cortical responses to each VF quadrant. Results showed the expected activation in the contralateral hemisphere, with respect to the side of the stimulated quadrant. We also measured significantly stronger activations in the upper visual cortex when low hemifield stimuli were presented compared to activations in the lower visual cortex when upper hemifield stimuli were shown, especially when the stimulation was presented in the right visual field. These findings confirm the vertical asymmetry of the visual cortex previously reported by neuroimaging and behavioral studies. More importantly, the present work confirms the reliability of the fNIRS technique for functional mapping of the human brain.
authors.affiliation: Centre de Recherche, Centre Hospitalier Universitaire Sainte-Justine, 3175 Chemin de la Côte Sainte-Catherine, Montréal, Canada H3T 1C5.
authors.forename: Danielle
authors.initials: D
authors.lastname: Bastien
authors.forename: Anne
authors.initials: A
authors.lastname: Gallagher
authors.forename: Julie
authors.initials: J
authors.lastname: Tremblay
authors.forename: Phetsamone
authors.initials: P
authors.lastname: Vannasing
authors.forename: Martin
authors.initials: M
authors.lastname: Thériault
authors.forename: Maryse
authors.initials: M
authors.lastname: Lassonde
authors.forename: Franco
authors.initials: F
authors.lastname: Lepore
mesh_terms: D000328:Adult; D001931:Brain Mapping; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010108:Oxyhemoglobins / Q000378:metabolism; D010775:Photic Stimulation; D019265:Spectroscopy, Near-Infrared; D014793:Visual Cortex / Q000378:metabolism*; D014794:Visual Fields / Q000502:physiology; D014795:Visual Pathways; D014796:Visual Perception / Q000502:physiology; D055815:Young Adult
chemical_list: D010108:Oxyhemoglobins