Assessment of magno-, parvo-, and koniocellular visual streams in migraine / by James Brazeau.
Brazeau, James N. R.
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Although visual abnormalities have been noted in migraine, no studies have specifically sought to assess all three visual processing streams. We are the first to psychophysically assess visual functionality of the magnocellular (MC), parvocellular (PC), and koniocellular (KC) parallel streams at different hierarchical visual pathway loci across groups of individuals with migraine with aura (MA; n = 13), migraine without aura (MWO; n = 14), and controls (o = 15). Participants completed four tasks: (I) visual field analysis using short-wave length automated perimetry (SWAP), (2) chromatic discrimination along cone-excitation axes using the Cambridge Colour Test, (3) chromatic contrast sensitivity across isoluminant bichromatic spatial Gabor gratings, and (4) luminance contrast sensitivity across heteroluminant spatial Gabor gratings. Our results suggest that deficits are selective to short-wavelength-sensitive cones and the associated KC visual stream. Furthermore, functional inconsistencies and consistencies between our SWAP and chromatic discrimination measures and SWAP and chromatic sensitivity measures, respectively, provide evidence for a retinal locus of dysfunction in MA that is compensated for at downstream locations within the KC visual stream.