title: Extrastriate projections in human optic radiation revealed by fMRI-informed tractography.
abstract: The human optic radiation (OR) is the main pathway for conveying visual input to occipital cortex, but it is unclear whether it projects beyond primary visual cortex (V1). In this study, we used functional MRI mapping to delineate early visual areas in 30 healthy volunteers and determined the termination area of the OR as reconstructed with diffusion tractography. Direct thalamo-cortical projections to areas V2 and V3 were found in all hemispheres tested, with a distinct anatomical arrangement of superior-inferior fiber placement for dorsal and ventral projections, respectively, and a medio-lateral nesting arrangement for projections to V1, V2 and V3. Finally, segment-specific microstructure was examined, revealing sub-fascicular information. This is to date the first in vivo demonstration of direct extrastriate projections of the OR in humans.
authors.affiliation: Institute of Child Health, University College London, London, WC1N 1EH, UK, ivan.alvarez.11@ucl.ac.uk.
authors.forename: Ivan
authors.initials: I
authors.lastname: Alvarez
authors.forename: D Samuel
authors.initials: DS
authors.lastname: Schwarzkopf
authors.forename: Chris A
authors.initials: CA
authors.lastname: Clark
mesh_terms: D000328:Adult; D000818:Animals; D001931:Brain Mapping; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D009412:Nerve Fibers / Q000502:physiology; D009778:Occipital Lobe / Q000033:anatomy & histology* / Q000000981:diagnostic imaging / Q000502:physiology; D011859:Radiography; D014793:Visual Cortex / Q000033:anatomy & histology* / Q000000981:diagnostic imaging / Q000502:physiology; D014795:Visual Pathways / Q000033:anatomy & histology* / Q000000981:diagnostic imaging / Q000502:physiology; D055815:Young Adult