Interictal Lack of Habituation of Mismatch Negativity in Migraine

Evaluation of Auditory Temporal Discrimination Thresholds in Migraine Patients

INTRODUCTION

Although vestibular migraine is well defined, the effects of migraine on the auditory system have not been clearly identified yet. The aim of this study was to determine the effect of migraine on the auditory system.

METHODS

Migraine patients without hearing loss were included in the study. Group 1 consisted of patients with migraine pain, group 2 consisted of patients with migraine in the interictal period, and group 3 consisted of healthy volunteers with similar demographic characteristics to groups 1 and 2. Random gap detection test was applied to all 3 groups. Additionally, group 2 and group 3 patients were evaluated with the auditory cortical potentials and the mismatch negativity test.

RESULTS

There was a statistically significant difference between the 3 groups in the random gap detection test. There was no statistically significant difference in auditory cortical potentials between group 2 and group 3; however, a statistically significant difference was found between the groups in terms of mismatch negativity test latency.

CONCLUSION

An auditory pathway may be affected in migraine patients, although hearing tests are normal. This interaction continues between attacks, being more evident during the pain period. Therefore, disorders of hearing or speech perception in migraine patients should be evaluated by further audiological tests.

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

Individuals with migraine generally experience photophobia and/or phonophobia during and between migraine attacks. Many different mechanisms have been postulated to explain these migraine phenomena including abnormal patterns of connectivity across the cortex. The results, however, remain contradictory and there is no clear consensus on the nature of the cortical abnormalities in migraine. Here, we uncover alterations in cortical patterns of coherence (connectivity) in interictal migraineurs during the presentation of visual and auditory stimuli and during rest. We used a high-density EEG system, with 128 customized electrode locations, to compare inter- and intra-hemispheric coherence in the interictal period from 17 individuals with migraine (12 female) and 18 age- and gender-matched healthy control subjects. During presentations of visual (vertical grating pattern) and auditory (modulated tone) stimulation which varied in temporal frequency (4 and 6 Hz), and during rest, participants performed a colour detection task at fixation. Analyses included characterizing the inter- and intra-hemisphere coherence between the scalp EEG channels over 2-s time intervals and over different frequency bands at different spatial distances and spatial clusters. Pearson's correlation coefficients were estimated at zero-lag. Repeated measures analyses-of-variance revealed that, relative to controls, migraineurs exhibited significantly (i) faster colour detection performance, (ii) lower spatial coherence of alpha-band activity, for both inter- and intra-hemisphere connections, and (iii) the reduced coherence occurred predominantly in frontal clusters during both sensory conditions, regardless of the stimulation frequency, as well as during the resting-state. The abnormal patterns of EEG coherence in interictal migraineurs during visual and auditory stimuli, as well as at rest (eyes open), may be associated with the cortical hyper-responsivity that is characteristic of abnormal sensory processing in migraineurs.

Neurophysiological correlates of abnormal auditory processing in episodic migraine during the interictal period

BACKGROUND

The characteristics of the hypersensitivity to auditory stimuli during the interictal period in episodic migraine are discussed. The combined use of event-related potentials, time-frequency power and phase-synchronization can provide relevant information about the time-course of sensory-attentional processing in migraine and its underlying mechanisms.

OBJECTIVE

The aim of this nested case-control study was to examine these processes in young, female, episodic migraine patients interictally and compare them to controls using an active auditory oddball task.

METHOD

We recorded, using 20 channels, the electrophysiological brain activity of 21 women with episodic migraine without aura and 21 healthy matched controls without family history of migraine, during a novelty oddball paradigm. We collected sociodemographic and clinical data as well as scores related to disability, quality of life, anxiety and depression. We calculated behavioural measures including reaction times, hit rates and false alarms. Spectral power and phase-synchronization of oscillatory activity as well as event-related potentials were obtained for standard stimuli. For target and novel stimuli, event-related potentials were acquired.

RESULTS

There were no significant differences at the behavioural level. In migraine patients, we found an increased phase-synchronization at the theta frequency range and a higher N1 response to standard trials. No differences were observed in spectral power. No evidence for a lack of habituation in any of the measures was seen between migraine patients and controls. The Reorienting Negativity was reduced in migraine patients as compared to controls on novel but not on target trials.

CONCLUSION

Our findings suggest that migraine patients process stimuli as more salient, seem to allocate more of their attentional resources to their surrounding environment, and have less available resources to reorient attention back to the main task.

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.

The impact of attack frequency and duration on neurocognitive processing in migraine sufferers: evidence from event-related potentials using a modified oddball paradigm

Background

Several studies have suggested that migraineurs suffer from neurocognitive abnormalities, but this phenomenon and exact mechanisms remain controversial. In this study, we aimed to reevaluate visual spatial attention via event-related potential (ERP) examinations and explore further correlations between ERP data and migraine characteristics.

Methods

Altogether, 25 migraine patients (9 males, 16 females; mean age 35.240 years) in the interictal period and 21 age-matched healthy controls (8 males, 13 females; mean age 35.286 years) were recruited. A modified visual oddball paradigm which contained standard, target and novel stimuli was used in the test, and amplitudes and latencies of corresponding original/difference ERP components were measured and analyzed independently.

Results

We found that P3 amplitude was markedly reduced in migraineurs. This phenomenon was further validated in analysis of difference P3 components (target minus standard and novel minus standard). Additionally, the N1 and N2 latencies elicited by novel stimulus were both delayed in patients compared with controls. Furthermore, these deviant cognitive ERPs were correlated with frequency and duration of migraine attacks.

Conclusions

These results indicated impaired visual spatial attention in migraine patients, which could be related to frequency and duration of attacks.

THE EFFECTS OF HYPNOSIS AND HYPNOTIC SUGGESTIONS ON THE MISMATCH NEGATIVITY IN HIGHLY HYPNOTIZABLE SUBJECTS

The neural mechanisms associated with hypnosis were investigated in a group of 9 high hypnotizable subjects by measuring the mismatch negativity (MMN) component of the auditory event-related potential (ERP). ERPs were recorded using a passive oddball paradigm to sinusoidal standard and deviant tone stimuli of 500 and 520 Hz, respectively, in four conditions: prehypnosis, neutral hypnosis, hypnotic suggestion for altering the tone perception, and posthypnotic conditions. Earlier studies have indicated that hypnosis and hypnotic suggestions might have an effect on MMN, but the results of our study contradict these results: No statistically significant differences were found between the conditions in the MMN amplitudes.

Central Nervous System Underpinnings of Sensory Hypersensitivity in Migraine: Insights from Neuroimaging and Electrophysiological Studies

Whereas considerable data have been generated about the pathophysiology of pain processing during migraine attacks, relatively little is known about the neural basis of sensory hypersensitivity. In migraine, the term "hypersensitivity" encompasses different and probably distinct pathophysiological aspects of sensory sensitivity. During attacks, many patients have enhanced sensitivity to visual, auditory and/or olfactory stimuli, which can enhance headache while interictally, migraineurs often report abnormal sensitivity to environmental stimuli that can cause nonpainful discomfort. In addition, sensorial stimuli can influence and trigger the onset of migraine attacks. The pathophysiological mechanisms and the origin of such sensitivity (individual predisposition to develop migraine disease or consequence of repeated migraine attacks) are ill understood. Functional neuroimaging and electrophysiological studies allow for noninvasive measures of neuronal responses to external stimuli and have contributed to our understanding of mechanisms underlying sensory hypersensitivity in migraine. The purpose of this review is to present pivotal neuroimaging and neurophysiological studies that explored the basal state of brain responsiveness to sensory stimuli in migraineurs, the alterations in habituation and attention to sensory inputs, the fluctuations of responsiveness to sensory stimuli before and during migraine attacks, and the relations between sensory hypersensitivity and clinical sensory complaints.

Central auditory processing and migraine: a controlled study

Background

This study aimed to verify and compare central auditory processing (CAP) performance in migraine with and without aura patients and healthy controls.

Methods

Forty-one volunteers of both genders, aged between 18 and 40 years, diagnosed with migraine with and without aura by the criteria of “The International Classification of Headache Disorders” (ICDH-3 beta) and a control group of the same age range and with no headache history, were included. Gaps-in-noise (GIN), Duration Pattern test (DPT) and Dichotic Digits Test (DDT) tests were used to assess central auditory processing performance.

Results

The volunteers were divided into 3 groups: Migraine with aura (11), migraine without aura (15), and control group (15), matched by age and schooling. Subjects with aura and without aura performed significantly worse in GIN test for right ear (p = .006), for left ear (p = .005) and for DPT test (p < .001) when compared with controls without headache, however no significant differences were found in the DDT test for the right ear (p = .362) and for the left ear (p = .190).

Conclusions

Subjects with migraine performed worsened in auditory gap detection, in the discrimination of short and long duration. They also presented impairment in the physiological mechanism of temporal processing, especially in temporal resolution and temporal ordering when compared with controls. Migraine could be related to an impaired central auditory processing.

Clinical trial registration

Research Ethics Committee (CEP 0480.10) – UNIFESP

Enhanced pain expectation in migraine: EEG-based evidence for impaired prefrontal function

BACKGROUND

Dysexcitability characterizes the interictal migraineous brain. The main central expressions of this dysexcitability are decreased habituation and enhanced anticipation and attention to pain and other external sensory stimuli.

OBJECTIVE

This study evaluates the effects of anticipation on pain modulation and their neural correlates in migraine.

METHODS

In 39 migraineurs (20 migraine with aura [MWA] and 19 migraine without aura [MOA]) and 22 healthy controls, cortical responses to 2 successive trains of noxious contact-heat stimuli, presented in either predicted or unpredicted manner, were analyzed using standardized low-resolution electromagnetic tomography key.

RESULTS

A lack of habituation to repeated predicted pain was associated with significantly increased pain-evoked potential amplitudes in MWAs (increase of 3.9 μV) and unchanged ones in MOAs (1.1 μV) but not in controls (decrease of 5 μV). Repeated unpredicted pain resulted in enhanced pain-evoked potential amplitudes in both MWA and MOA groups (increase of 5.5 μV and 4.4 μV, respectively) compared with controls (decrease of 0.2 μV). Source localization revealed reduced activations in the anterior-medial prefrontal cortices and subsequent increased somatosensory activity in migraineurs (P < .05). The prefrontal-somatosensory dysfunction positively correlated with lifetime headache duration (P < .05) and concern of upcoming migraine attacks (P < .05) in MWAs, and with frequency of migraine attacks in MOAs (P < .05).

CONCLUSIONS

Our findings of impaired modulation of anticipated pain in migraine suggest a heightened state of anticipatory readiness combined with ineffective recruitment of prefrontal inhibitory pathways during experience of pain; the latter might account for the former, at least partially. In line, less efficient inhibitory capability is a plausible mechanistic explanation for patients' high concern about their upcoming migraine attacks.

Spontaneous trigeminal allodynia in rats: a model of primary headache

Animal models are essential for studying the pathophysiology of headache disorders and as a screening tool for new therapies. Most animal models modify a normal animal in an attempt to mimic migraine symptoms. They require manipulation to activate the trigeminal nerve or dural nociceptors. At best, they are models of secondary headache. No existing model can address the fundamental question: How is a primary headache spontaneously initiated? In the process of obtaining baseline periorbital von Frey thresholds in a wild-type Sprague-Dawley rat, we discovered a rat with spontaneous episodic trigeminal allodynia (manifested by episodically changing periorbital pain threshold). Subsequent mating showed that the trait is inherited. Animals with spontaneous trigeminal allodynia allow us to study the pathophysiology of primary recurrent headache disorders. To validate this as a model for migraine, we tested the effects of clinically proven acute and preventive migraine treatments on spontaneous changes in rat periorbital sensitivity. Sumatriptan, ketorolac, and dihydroergotamine temporarily reversed the low periorbital pain thresholds. Thirty days of chronic valproic acid treatment prevented spontaneous changes in trigeminal allodynia. After discontinuation, the rats returned to their baseline of spontaneous episodic threshold changes. We also tested the effects of known chemical human migraine triggers. On days when the rats did not have allodynia and showed normal periorbital von Frey thresholds, glycerol trinitrate and calcitonin gene related peptide induced significant decreases in the periorbital pain threshold. This model can be used as a predictive model for drug development and for studies of putative biomarkers for headache diagnosis and treatment.

The mismatch negativity (MMN)--a unique window to disturbed central auditory processing in ageing and different clinical conditions

In this article, we review clinical research using the mismatch negativity (MMN), a change-detection response of the brain elicited even in the absence of attention or behavioural task. In these studies, the MMN was usually elicited by employing occasional frequency, duration or speech-sound changes in repetitive background stimulation while the patient was reading or watching videos. It was found that in a large number of different neuropsychiatric, neurological and neurodevelopmental disorders, as well as in normal ageing, the MMN amplitude was attenuated and peak latency prolonged. Besides indexing decreased discrimination accuracy, these effects may also reflect, depending on the specific stimulus paradigm used, decreased sensory-memory duration, abnormal perception or attention control or, most importantly, cognitive decline. In fact, MMN deficiency appears to index cognitive decline irrespective of the specific symptomatologies and aetiologies of the different disorders involved.

Short-term effects of processing musical syntax: an ERP study

We investigated influences of short-term experience on music-syntactic processing, using a chord-sequence paradigm in which sequences ended on a harmony that was syntactically either regular or irregular. In contrast to previous studies (in which block durations were rather short), chord sequences were presented to participants for around 2 h while they were watching a silent movie with subtitles. Results showed that the music-syntactically irregular chord functions elicited an early right anterior negativity (ERAN), and that the ERAN amplitude significantly declined over the course of the experiment. The ERAN has previously been suggested to reflect the processing of music-syntactic irregularities, and the present data show that the cognitive representations of musical regularities are influenced by the repeated presentation of unexpected, irregular harmonies. Because harmonies were task-irrelevant, the data suggest that cognitive representations of musical regularities can change implicitly, i.e., even when listeners do not attend to the harmonies, and when they are presumably oblivious of the changes of such representations. Although the ERAN amplitude was significantly reduced, it was still present towards the end of the experiment at the right anterior electrodes, indicating that cognitive representations of basic music-syntactic regularities cannot easily be erased.

Transcranial direct current stimulation reveals inhibitory deficiency in migraine

The issue of interictal excitability of cortical neurons in migraine patients is controversial: some studies have reported hypo-, others hyperexcitability. The aim of the present study was to observe the dynamics of this basic interictal state by further modulating the excitability level of the visual cortex using transcranial direct current stimulation (tDCS) in migraineurs with and without aura. In healthy subjects anodal tDCS decreases, cathodal stimulation increases transcranial magnetic stimulation (TMS)-elicited phosphene thresholds (PT), which is suggested as a representative value of visual cortex excitability. Compared with healthy controls, migraine patients tended to show lower baseline PT values, but this decrease failed to reach statistical significance. Anodal stimulation decreased phosphene threshold in migraineurs similarly to controls, having a larger effect in migraineurs with aura. Cathodal stimulation had no significant effect in the patient groups. This result strengthens the notion of deficient inhibitory processes in the cortex of migraineurs, which is selectively revealed by activity-modulating cortical input.

Tinnitus in Migraine: An Allodynic Symptom Secondary to Abnormal Cortical Functioning?

Tinnitus is not a common auditory symptom in migraine. Recent research suggests that central sensitization (CS) develops in most migraneurs during the course of a migraine attack. Herein we describe 3 patients with primary headache disorders and tinnitus as their chief complaint, in whom the tinnitus intensity consistently increased during headache attacks. In headache patients, tinnitus may be related to spontaneous and aberrant neural activity at any level along the auditory axis, with abnormal reorganization processes in the auditory cortex following hearing receptor damage. We hypothesize that the tinnitus intensity increase could be an allodynic symptom related to CS, or alternatively could be associated with cortical hyperexcitability.