Cortical Hyper‐Excitability in Migraine in Response to Chromatic Patterns

Abstract

Objective Individuals with migraine exhibit heightened sensitivity to visual input that continues beyond their migraine episodes. However, the contribution of color to visual sensitivity, and how it relates to neural activity, has largely been unexplored in these individuals. Background Previously, it has been shown that, in non‐migraine individuals, patterns with greater chromaticity separation evoked greater cortical activity, regardless of hue, even when colors were isoluminant. Therefore, to investigate whether individuals with migraine experienced increased visual sensitivity, we compared the behavioral and neural responses to chromatic patterns of increasing separation in migraine and non‐migraine individuals. Methods Seventeen individuals with migraine (12 with aura) and 18 headache‐free controls viewed pairs of colored horizontal grating patterns that varied in chromaticity separation. Color pairs were either blue‐green, red‐green, or red‐blue. Participants rated the discomfort of the gratings and electroencephalogram was recorded simultaneously. Results Both groups showed increased discomfort ratings and larger N1/N2 event‐related potentials (ERPs) with greater chromaticity separation, which is consistent with increased cortical excitability. However, individuals with migraine rated gratings as being disproportionately uncomfortable and exhibited greater effects of chromaticity separation in ERP amplitude across occipital and parietal electrodes. Ratings of discomfort and ERPs were smaller in response to the blue‐green color pairs than the red‐green and red‐blue gratings, but this was to an equivalent degree across the 2 groups. Conclusions Together, these findings indicate that greater chromaticity separation increases neural excitation, and that this effect is heightened in migraine, consistent with the theory that hyper‐excitability of the visual system is a key signature of migraine.

Abnormalities in cortical pattern of coherence in interictal migraine detected using ultra high-density EEG

“…We used a custom-designed high-density EEG nylon cap with electrodes specifically positioned so as to cover with high resolution just over central occipital, parietal, and frontal areas (the locations of alterations typically reported in previous studies of migraine). More details of the electrode locations are available in our previous paper (Haigh et al, 2019). Electrodes were placed (Haigh et al, 2019).…”

“…More details of the electrode locations are available in our previous paper (Haigh et al, 2019). Electrodes were placed (Haigh et al, 2019). approximately 1.4 cm distance from one another.…”

“…Studies focusing on sensory-evoked responses in migraine have generally found larger responses, in both fMRI (Huang et al, 2003(Huang et al, , 2011Coutts et al, 2012;Cucchiara et al, 2015) and EEG (Ambrosini et al, 2017;Haigh et al, 2019), and reduced habituation to repeated stimuli (Kropp and Gerber, 1993) compared to controls. This evidence is consistent with cortical hyperexcitability in migraine.…”

Response inhibition alterations in migraine: Evidence from event-related potentials and evoked oscillations

“…Available evidence supporting this claim is mainly based on previous studies on the cortical response to external sensory stimuli in migraineurs (10,14,21,22). For example, reliable differences in cortical disexcitability in response to sensory stimulation between migraineurs and healthy controls have been found, usually re ected by increased amplitude of evoked responses (17,23,24) and decreased activity of GABA-mediated inhibition of the sensory cortex (25). Given that inhibition control does not take place only at the sensory level (such as inhibition of previously activated sensory processes), it can play an important role across early to later stage of information processing, such as inhibition of irrelevant information or an initiated response (26,27).…”

Response inhibition alterations in migraine: An event-related potential study

“…Available evidence supporting this claim has come mainly from previous studies on the cortical response to external sensory stimuli in migraineurs (12,16,20,21). For example, reliable differences in cortical excitability in response to sensory stimulation between migraineurs and healthy controls have been found, usually re ected by increased amplitude of evoked responses (19,22,23) and decreased activity of GABA-mediated inhibition of the sensory cortex (24). Given that inhibitory control does not take place only at the sensory level and can play an important role across early to later stage of information processing (25,26), it is tempting to understand the possible role of other dimensions of inhibition control, such as inhibition of an initiated response, can play in migraine disability.…”