Abstract
Background: Using conventional visual evoked potentials (VEPs), migraine patients were found to be hyperresponsive to visual stimulus. Considering that a significant portion of neuronal activity is lost for analysis in the averaging process of conventional VEPs, in this study we investigated visual evoked responses of migraine patients and healthy volunteers using a different approach: single trial analysis. This method permits to preserve all stimulus-induced neuronal activations, whether they are synchronized or not. In addition, we used MRI voxel-based morphometry to search for cortical regions where gray matter volume correlated with single trial (st) VEP amplitude. Finally, using resting-state functional MRI, we explored the connectivity between these regions.Results: stVEP amplitude was greater in episodic migraine patients than in healthy volunteers. Moreover, in migraine patients it correlated positively with gray matter volume of several brain areas likely involved in visual processing, mostly belonging to the ventral attention network. Finally, resting state functional connectivity corroborated the existence of functional interactions between these areas and helped delineating their directions.Conclusions: st-VEPs appear to be a reliable measure of cerebral responsiveness to visual stimuli. Mean st-VEP amplitude is higher in episodic migraine patients compared to controls. Visual hyper-responsiveness in migraine involves several functionally-interconnected brain regions, suggesting that it is the result of a complex multi-regional process coupled to stimulus driven attention systems rather than a localized alteration.
Highlights
Migraine patients are thought to be hyperresponsive to visual stimuli [1]
Voxel-Based Morphometry In episodic migraine without aura (EM) patients, mean single-trial analysis of evoked potentials (st-visual evoked potentials (VEPs)) amplitude was positively correlated with gray matter volume in the right temporoparietal junction, peaking at the angular gyrus [whole brain analysis: 42, −57, 29 p family-wise error (FWE) = 0.006 T = 7.07]
We found that neural activation to single visual stimulus, as reflected by st-VEP, is greater in episodic migraine patients than in healthy subjects
Summary
Migraine patients are thought to be hyperresponsive to visual stimuli [1]. Despite major advancements [2], this phenomenon of which the underlying mechanisms remain largely undetermined, is often unseen by current methods [3]. In order to distinguish synchronized, stimulusrelated, cortical activity from background noise (i.e., to increase the signal-to-noise ratio), hundreds of brief periods of poststimulus electroencephalographic registry (trials), are pointby-point averaged This method, may hide some important aspects of neuronal dynamics, since it may not capture unsynchronized, yet stimulus-induced, activity embedded in what is presumed to be noise (Figure 1) [18, 19]. Considering that a significant portion of neuronal activity is lost for analysis in the averaging process of conventional VEPs, in this study we investigated visual evoked responses of migraine patients and healthy volunteers using a different approach: single trial analysis. This method permits to preserve all stimulus-induced neuronal activations, whether they are synchronized or not. Using resting-state functional MRI, we explored the connectivity between these regions
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