Evidence for increased background neural noise in migraine with aura: Hyperactive but not hyperresponsive

Area of Science:

• Neuroscience
• Ophthalmology
• Visual electrophysiology

Background:

• Individuals with migraine with aura (MA) often display heightened electrophysiological responses alongside diminished visual task performance.
• Increased neural 'noise' in the visual cortex is a potential explanation for these visual processing deficits in MA.

Purpose of the Study:

• To investigate and compare contrast gain between individuals with migraine and those with photosensitive epilepsy.
• To evaluate the impact of precision ophthalmic tints (POTs) on contrast gain in migraine patients.

Main Methods:

• A case-control study measured steady-state visual evoked potentials (SSVEPs) in 15 MA patients and 15 controls.
• Stimuli included sinewave gratings varying in contrast and flicker frequency (5 and 17 Hz).
• The effect of colored spectacles (POTs) on electroencephalogram (EEG) responses and discomfort judgments was assessed.

Main Results:

• The MA group exhibited significantly increased background EEG activity at a 17 Hz flicker rate compared to controls.
• Contrast response functions were similar between MA patients and controls, suggesting normal contrast gain control.
• Migraine patients reported greater discomfort, and faster flicker rates were perceived as more uncomfortable by both groups.

Conclusions:

• Elevated EEG responses in MA patients provide evidence for increased neural 'noise' in the migraine brain.
• Findings suggest typical contrast gain control in migraine, differing from abnormalities observed in photosensitive epilepsy.
• POTs may reduce visual discomfort but do not appear to specifically modulate contrast gain in migraine.