<p>The Psychophysical Assessment of Hierarchical Magno-, Parvo- and Konio-Cellular Visual Stream Dysregulations in Migraineurs</p>

Abstract

IntroductionAlthough conscious, image-forming illusions have been noted in migraine, few studies have specifically sought to collectively evaluate the role of all three parallel visual processing streams in the retinogeniculostriate pathway involved with image-forming vision and their implications in the development of migraine symptoms.MethodsWe psychophysically assessed the functionality of the inferred magnocellular (MC), parvocellular (PC), and koniocellular (KC) streams at different hierarchical loci across three clinical groups: individuals who experience migraine with aura (MA; n=13), experience migraine without aura (MWO; n=14), and Controls (n=15). Participants completed four experiments: Experiment 1 designed to assess retinal short-wavelength-sensitive (S-) cone sensitivities; Experiment 2 intended to measure postretinal temporal and spatiochromatic contrast sensitivities; Experiment 3 intended to assess postretinal spatiotemporal achromatic contrast sensitivities; and Experiment 4 designed to measure thalamocortical color discriminations along the three cone-excitation axes.ResultsS-cone deficits were revealed with greater retinal areas being affected in MA compared to MWO participants. Findings across the four experiments suggest a prominent retinal locus of dysfunction in MA (lesser in MWO) with potential feedforward compensations occurring within the KC visual stream.ConclusionComplex, integrative network compensations need to be factored in when considering the dysregulating influences of migraine along the visual pathway.

Functional impairment of the Lateral Geniculate Nucleus in Multiple Sclerosis

“…According to previous physiological studies, the M, P, and K layers in the LGN region are provoked by a combination of retinal photoreceptor output. Moreover, the frequency sensitivity of P and K streams are similar to each other (McKeefry et al, 2001;Wesner & Brazeau, 2019). Therefore, both K and P may be provoked in response to chromatic visual stimulation.…”

Evaluation of migraine without aura patients by visual evoked potentials with different spatial frequencies

“…A study by McKendrick et al evaluated migraine patients and a loss in low spatial frequency contrast sensitivity was detected due to reduced functions of both M and P pathways [31]. A psychophysical assessment of migraneurs revealed S-cone deficits with a greater area of the retina showing integrative network compensations need to be factored [32]. A study by Yenice et al detected reduced contrast sensitivity in low and high spatial frequencies in patients with migraine [33].…”