Pre-attentive dysfunction of processing emotional faces in interictal migraine revealed by expression-related visual mismatch negativity.

BACKGROUND

Several investigations have indicated emotional processing impairment in migraineurs, while no report is available considering the automatic processing of emotional information. In this study, we aimed to characterize the pre-attentive processing of facial expressions in migraine sufferers by recording and analyzing expression-related visual mismatch negativity (EMMN).

METHODS

Altogether, 30 migraineurs (19 females) during the interictal period and 30 age-matched healthy controls (17 females) were recruited. An expression-related oddball paradigm was used to investigate automatic emotional processing, and a group of schematic emotional faces (neutral, happy, sad) unrelated to the participant's task were employed in the experiment in order to avoid low-level processing.

RESULTS

There was no significant difference in behavioral performance (the response accuracy and reaction time) between migraine patients and healthy controls. Nevertheless, the mean EMMN amplitudes within the ranges of 150-250 ms and 250-350 ms were markedly attenuated in patients compared with controls, regardless of happy or sad condition (happy minus neutral or sad minus neutral), and sad EMMN was observed to be larger than happy EMMN only in healthy participants. Moreover, these electrophysiological data directly correlated with frequency and duration of migrainous attacks.

CONCLUSIONS

Our findings implied that the pre-attentive dysfunction of processing both happy and sad expressions was demonstrated in interictal migraineurs, without the existence of negative bias (sad superiority) effect. Further studies on the availability of EMMN as an evaluative marker for migraine are warranted.