In Vivo Identification of Thick, Thin, and Pale Stripes of Macaque Area V2 Using Submillimeter Resolution (f)MRI at 3 T

• Published in: Cerebral cortex (New York, N.Y. 1991) Vol. 29; no. 2; pp. 544 - 560
• Main Authors: Li, Xiaolian, Zhu, Qi, Janssens, Thomas, Arsenault, John T, Vanduffel, Wim
• Format: Journal Article
• Language: English
• Published: United States Oxford University Press 01.02.2019
• Subjects: Animals; Color Perception - physiology; Female; Macaca mulatta; Magnetic Resonance Imaging - methods; Male; Pattern Recognition, Visual - physiology; Photic Stimulation - methods; Visual Cortex - diagnostic imaging; Visual Cortex - physiology; Visual Pathways - diagnostic imaging; Visual Pathways - physiology; myelin; high-resolution fMRI; color; disparity; columns
• ISSN: 1047-3211; 1460-2199
• DOI: 10.1093/cercor/bhx337

Abstract Primate area V2 contains a repetitive pattern of thick, thin and pale cytochrome oxidase stripes that are characterized by largely discrete in- and output channels, as well as differences in function, and myelo- and cytoarchitecture. Stripes have been identified mainly using microscope-based imaging of tiny portions of superficially located V2, or by postmortem methods, hence, the quest for (quasi) noninvasive tools to study these mesoscale functional units. Only recently, stripe-like V2 patterns have been demonstrated in humans with high-field (functional) magnetic resonance imaging (f)MRI, but in both such studies only 2 stripe compartments could be identified. Although interstripe distances in monkeys are ~half of those in humans, we show that all 3 V2 stripe classes can be reliably separated using submillimeter (f)MRI (0.6 mm isotropic voxels) on regular 3 T scanners by combining contrast agents and implanted phased-array coils. Specifically, we show highly reproducible fMRI patterns, both within and across subjects, of color-selective thin and disparity-selective thick stripes. Furthermore, reliable MRI-based higher myelin-density was observed in pale stripes. Hence, this is the first study showing segregation of columns using (f)MRI-based methods in macaque cortex, which opens the possibility of studying these elementary building blocks of the visual system noninvasively on a large scale.