Pain-related cerebral activation is altered by a distracting cognitive task

Efficacy of Flippits to Reduce Pain in Children during Venipuncture - A Randomized Controlled Trial

OBJECTIVES

To investigate the efficacy of distraction by flippits/distraction cards in relieving pain associated with pediatric venipuncture process in young children.

METHODS

This study was a prospective, non-blinded, randomized controlled trial. The sample consisted of 210 children aged 4 to 6 y undergoing phlebotomy in the sampling room of the Advanced Pediatric Center outpatient department and were randomly assigned to control and intervention groups. Latter were exposed to distraction using flippits/distraction cards during the procedure. Pain was assessed for both groups by using FLACC (Face Legs Activity Cry Consolability) behavior pain assessment scale. In addition, procedural pain was also assessed by Wong Bakers Faces Pain Scale (WBFPS) using children and parents' report.

RESULTS

Flippits (distraction cards) had a significant effect on behavioral response to pain in children during blood sampling as evidenced by lower mean pain scores in the intervention group (2.75 ± 0.97) as compared to the control group (3.24 ± 0.85) as per FLACC behavioral pain assessment scale (p < 0.001). Parents and self reported pain as per Wong Baker Faces Pain Scale was also lower in the intervention group as compared to the control group (p < 0.001). Odds of severe pain/discomfort (total pain score 7-10) were 2.5 times higher in controls as compared to the intervention group (OR 2.5; 95% CI: 1.40-4.45) (P 0.002).

CONCLUSIONS

The use of simple distraction technique using flippits can significantly relieve the pain associated with blood sampling in children.

High-resolution functional MRI identified distinct global intrinsic functional networks of nociceptive posterior insula and S2 regions in squirrel monkey brain

Numerous functional imaging and electrophysiological studies in humans and animals indicate that the two contiguous areas of secondary somatosensory cortex (S2) and posterior insula (pIns) are core regions in nociceptive processing and pain perception. In this study, we tested the hypothesis that the S2-pIns connection serves as a hub for connecting distinct sensory and affective nociceptive processing networks in the squirrel monkey brain. At 9.4T, we first mapped the brain regions that respond to nociceptive heat stimuli with high-resolution fMRI, and then used seed-based resting-state fMRI (rsfMRI) analysis to delineate and refine the global intrinsic functional connectivity circuits of the proximal S2 and pIns regions. In each subject, nociceptive (47.5°C) heat-evoked fMRI activations were detected in many brain regions, including primary somatosensory (S1), S2, pIns, area 7b, anterior cingulate cortex (ACC), primary motor cortex, prefrontal cortex, supplementary motor area, thalamus, and caudate. Using the heat-evoked fMRI activation foci in S2 and pIns as the seeds, voxel-wise whole-brain resting-state functional connectivity (rsFC) analysis revealed strong functional connections between contralateral S2 and pIns, as well as their corresponding regions in the ipsilateral hemisphere. Spatial similarity and overlap analysis identified each region as part of two distinct intrinsic functional networks with 7% overlap: sensory S2-S1-area 7b and affective pIns-ACC-PCC networks. Moreover, a high degree of overlap was observed between the combined rsFC maps of nociceptive S2 and pIns regions and the nociceptive heat-evoked activation map. In summary, our study provides evidence for the existence of two distinct intrinsic functional networks for S2 and pIns nociceptive regions, and these two networks are joined via the S2-pIns connection. Brain regions that are involved in processing nociceptive inputs are also highly interconnected at rest. The presence of robust and distinct S1-S2-area 7b and pIns-ACC-PCC rsFC networks under anesthesia underscores their fundamental roles in processing nociceptive information.

5-HT modulation of pain perception in humans

INTRODUCTION

Although there is clear evidence for the serotonergic regulation of descending control of pain in animals, little direct evidence exists in humans. The majority of our knowledge comes from the use of serotonin (5-HT)-modulating antidepressants as analgesics in the clinical management of chronic pain.

OBJECTIVES

Here, we have used an acute tryptophan depletion (ATD) to manipulate 5-HT function and examine its effects of ATD on heat pain threshold and tolerance, attentional manipulation of nociceptive processing and mood in human volunteers.

METHODS

Fifteen healthy participants received both ATD and balanced amino acid (BAL) drinks on two separate sessions in a double-blind cross-over design. Pain threshold and tolerance were determined 4 h post-drink via a heat thermode. Additional attention, distraction and temperature discrimination paradigms were completed using a laser-induced heat pain stimulus. Mood was assessed prior and throughout each session.

RESULTS

Our investigation reported that the ATD lowered plasma TRP levels by 65.05 ± 7.29% and significantly reduced pain threshold and tolerance in response to the heat thermode. There was a direct correlation between the reduction in total plasma TRP levels and reduction in thermode temperature. In contrast, ATD showed no effect on laser-induced pain nor significant impact of the distraction-induced analgesia on pain perception but did reduce performance of the painful temperature discrimination task. Importantly, all findings were independent of any effects of ATD on mood.

CONCLUSION

As far as we are aware, it is the first demonstration of 5-HT effects on pain perception which are not confounded by mood changes.

Altered Metabolism in Frontal Brain Circuits in Cluster Headache

Neuroimaging studies have explored cerebral activation patterns in patients with cluster headache (CH) during attacks and have revealed activation of multiple brain areas known to belong to the general pain-processing network. However, it is still unclear which changes in brain metabolism are inherent to the shift from the ‘in bout’ to the ‘out of bout’ period. We measured cerebral glucose metabolism in 11 episodic CH patients during the cluster and again during the remission period with 18F-fluoro-2-deoxy-D-glucose-positron emission tomography (FDG-PET) and compared these data with 11 healthy controls. ‘In bout’ compared with ‘out of bout’ scans were associated with increases of metabolism in the perigenual anterior cingulate cortex (ACC), posterior cingulate cortex, prefrontal cortex, insula, thalamus and temporal cortex. Decreases in metabolism were observed in the cerebellopontine area. Compared with healthy volunteers, hypometabolism in the patient group (‘in bout’ and ‘out of bout’) was found in the perigenual ACC, prefrontal and orbitofrontal cortex. Thus, FDG-PET in CH patients revealed ‘in bout’ activation of brain structures which are involved in descending pain control. Compared with controls, the regional brain metabolism was constitutively decreased in most of these structures, irrespective of the bout. This finding indicates a deficient top-down modulation of antinociceptive circuits in CH patients. We suggest that trigger mechanisms of CH are insufficiently controlled and thus promote the initiation of the bout period and acute attack.

Brain imaging of pain: state of the art

Pain is a complex sensory and emotional experience that is heavily influenced by prior experience and expectations of pain. Before the development of noninvasive human brain imaging, our grasp of the brain's role in pain processing was limited to data from postmortem studies, direct recording of brain activity, patient experience and stimulation during neurosurgical procedures, and animal models of pain. Advances made in neuroimaging have bridged the gap between brain activity and the subjective experience of pain and allowed us to better understand the changes in the brain that are associated with both acute and chronic pain. Additionally, cognitive influences on pain such as attention, anticipation, and fear can now be directly observed, allowing for the interpretation of the neural basis of the psychological modulation of pain. The use of functional brain imaging to measure changes in endogenous neurochemistry has increased our understanding of how states of increased resilience and vulnerability to pain are maintained.

Effects of Distraction on Pain, Fear, and Distress During Venous Port Access and Venipuncture in Children and Adolescents With Cancer

This study evaluates the effect of self-selected distracters (ie, bubbles, I Spy: Super Challenger book, music table, virtual reality glasses, or handheld video games) on pain, fear, and distress in 50 children and adolescents with cancer, ages 5 to 18, with port access or venipuncture. Using an intervention-comparison group design, participants were randomized to the comparison group (n = 28) to receive standard care or intervention group (n = 22) to receive distraction plus standard care. All participants rated their pain and fear, parents rated participant fear, and the nurse rated participant fear and distress at 3 points in time: before, during, and after port access or venipuncture. Results show that self-reported pain and fear were significantly correlated (P = .01) within treatment groups but not significantly different between groups. Intervention participants demonstrated significantly less fear (P <.001) and distress (P = .03) as rated by the nurse and approached significantly less fear (P = .07) as rated by the parent. All intervention parents said the needlestick was better because of the distracter. The authors conclude that distraction has the potential to reduce fear and distress during port access and venipuncture.

Functional Imaging and Pain: Behavior, Perception, and Modulation

Time-dependent increases of local metabolic or blood flow rates have been described in spinal cord and brain during acute and chronic pain states in experimental animals, in parallel with changes of different behavioral endpoints of pain and hyperalgesia. In healthy human volunteers, pain intensity-related hemo-dynamic changes have been identified in a widespread, bilateral brain system including parietal, insular, cingulate, and frontal cortical areas, as well as thalamus, amygdala, and midbrain. Specific patterns of activity may characterize hyperalgesic states and some chronic pain conditions. Forebrain nociceptive systems are under inhibitory control by endogenous opioids and can be affected by acute administration of [.proportional]-opioid receptor agonists. Anticipation of pain may in itself induce changes in brain nociceptive networks. Moreover, pain-related cortical activity can be modulated by hypnotic suggestions, focusing or diverting attention, and placebo. These findings begin to disclose the spatio-temporal dynamics of brain networks underlying pain perception and modulation.

Impact of concurrent cognitive processing on cold pain perception: Implications for pain management and its neurobiological basis

Findings for heat pain have shown consistent pain attenuation through concurrent cognitive task completion; but only a minimal amount of studies have explored that for cold pain. This study investigated the direct impact of two well-established cognitive tasks on cold pain tolerance. In a within-subject design, 36 female Hong Kong locals were required to complete a baseline pain tolerance measurement, induced by the well-established Cold Pressor Test. This was followed by the counterbalanced presentation of the Colour Stroop or the Judgment of Line Orientation task with and without concurrent pain administration. As suggested by the Limited Capacity, Multiple Resource, and Cognitive-Affective Models, participants were expected to tolerate pain for significantly longer durations when they perform either concurrent Colour Stroop or concurrent Judgment of Line Orientation tasks compared to baseline measures with no concurrent task. The findings clearly indicated increased pain tolerance times during task completion compared with baseline measures, providing support for the a-priori hypothesis. The results contribute to existing literature by confirming increased cold pain tolerance during selective attention to cognitive tasks and extending this finding to tasks previously established in heat pain but not for cold pain research.

Altered effective connectivity of posterior thalamus in migraine with cutaneous allodynia: a resting-state fMRI study with Granger causality analysis

BACKGROUND

Most migraineurs develop cutaneous allodynia (CA) during migraine, and the underlying mechanism of CA in migraine is thought to be sensitization of the third-order trigeminovascular neurons in the posterior thalamic nuclei. This study aimed to investigate whether the ascending/descending pathway associated with the thalamus is disturbed in migraineurs with CA (MWCA) using effective connectivity analysis of resting-state functional magnetic resonance imaging.

METHODS

Thirty four migraineurs without aura (14 MWCA and 20 migraineurs without CA (MWoCA)) and 25 matched healthy controls (HC) were recruited in the study. The effective connectivity pathways associated with the posterior thalamus (PTH) were investigated using the Granger causality analysis. We chose bilateral PTH as two individual seeds, and compared MWCA with MWoCA and HC, respectively. Spearman correlation analysis was performed to test the correlation between the abnormal effective connectivity and the allodynia severity of MWCA.

RESULTS

Compared with MWoCA, MWCA showed decreased inflows from the left limbic regions and dorsal medial prefrontal cortex (dmPFC) to the ipsilateral PTH, as well as increased inflow from the right ventral medial prefrontal cortex (vmPFC) to the ipsilateral PTH; no significantly different outflows from the bilateral PTH to other regions were found. Compared with HC, MWCA showed increased outflows from the left PTH to the bilateral vmPFC, decreased outflows from the right PTH to the bilateral temporoparietal areas, decreased inflow from the left parietooccipital area to the ipsilateral PTH, and increased inflows from the right dorsolateral prefrontal cortex and the bilateral temporoparietal areas to the right PTH. Correlation analyses revealed that the disturbed connectivities between PTH and cuneus, as well as PTH and middle frontal gyrus were associated with the allodynia severity of MWCA.

CONCLUSIONS

MWCA demonstrated disrupted effective connection pathways between the PTH and other cortical or subcortical regions that participated in multi-dimentional pain processing. Our findings highlight the dysfunctional ascending and descending pain network at the thalamic-level and may help to illuminate the possible pathophysiologic mechanisms of CA.

The effect of repeated laser stimuli to ink-marked skin on skin temperature-recommendations for a safe experimental protocol in humans

Background. Nd:YAP laser is widely used to investigate the nociceptive and pain systems, generating perpetual and laser-evoked neurophysiological responses. A major procedural concern for the use of Nd:YAP laser stimuli in experimental research is the risk of skin damage. The absorption of Nd:YAP laser stimuli is greater in darker skin, or in pale skin that has been darkened with ink, prompting some ethics boards to refuse approval to experimenters wishing to track stimulus location by marking the skin with ink. Some research questions, however, require laser stimuli to be delivered at particular locations or within particular zones, a requirement that is very difficult to achieve if marking the skin is not possible. We thoroughly searched the literature for experimental evidence and protocol recommendations for safe delivery of Nd:YAP laser stimuli over marked skin, but found nothing.

Methods. We designed an experimental protocol to define safe parameters for the use of Nd:YAP laser stimuli over skin that has been marked with black dots, and used thermal imaging to assess the safety of the procedure at the forearm and the back.

Results. Using thermal imaging and repeated laser stimulation to ink-marked skin, we demonstrated that skin temperature did not increase progressively across the course of the experiment, and that the small change in temperature seen at the forearm was reversed during the rest periods between blocks. Furthermore, no participant experienced skin damage due to the procedure.

Conclusion. This protocol offers parameters for safe, confident and effective experimentation using repeated Nd:YAP laser on skin marked with ink, thus paving the way for investigations that depend on it.

The Music Attentiveness Screening Assessment, Revised (MASA-R): A Study of Technical Adequacy

BACKGROUND

Evidence suggests that attention is an important consideration when designing procedural support interventions for children undergoing distressing medical procedures. As such, the extent to which children can attend to musical stimuli used during music-based procedural support interventions would seem important. The Music Attentiveness Screening Assessment (MASA) was designed to assess a child's ability to attend to musical stimuli, but further revisions were deemed necessary to improve administration, test-retest reliability, and interobserver agreement for the measure's items.

OBJECTIVE

This study investigated the technical adequacy of the Music Attentiveness Screening Assessment, Revised (MASA-R), with a non-clinical sample of children aged 4 to 9 years by examining (a) Construct validity using comparator instruments measuring auditory attention; (b) Test-retest reliability following a two-week delay; and (c) Interobserver agreement when administered by two independent examiners.

METHODS

This non-clinical sample included 69 children who were administered both items from MASA-R and two comparator instruments: the Auditory Attention subtest from the NEPSY-II (NII-AA) for children aged 5 to 9 years (n = 47); and the Auditory Attention subtest from the Woodcock-Johnson Tests of Cognitive Abilities, 3rd ed. (WJIII-AA), for children aged 4 years (n = 22).

RESULTS

A significant proportion of score variance was shared by both MASA-R items and the comparator measures: R (2) = .16, F(2, 66) = 6.30, p = .003. MASA-R score estimates with regard to test-retest reliability (Item I, intra-class correlation [ICC] = .88; Item II, ICC = .91) and interobserver agreement (Item I, ICC = .99; Item II, ICC = .98) also fell into acceptable ranges.

CONCLUSIONS

Estimates of MASA-R score construct validity, test-retest reliability, and interobserver agreement appear improved over its predecessor, MASA. While findings are promising, additional investigation of its use with a clinical sample is needed before it can be confidently used in pediatrics.

Pain management in photoepilation

The hair follicle is a complex, hormonally active structure with permanent and cyclically renewed parts which are highly innervated by myelinated and unmyelinated afferent fibers. Hair removal, a very ancient practice, affects this sensory network and causes both acute and diffuse pain associated with inflammatory reaction. Optic permanent hair removal is becoming a popular alternative to traditional methods such as shaving, waxing, among other methods. These optical removal devices thermally destroy the target chromophore, that is, melanin, without damaging the surrounding skin. The increase in the skin surface temperature causes mild-to-severe pain, and optical hair removal has to be combined with pain relieving devices. Pain management relies on topical anesthetic agents, cooling devices, or non-noxious cutaneous stimulation whose mechanisms of action and efficiency are discussed in this article.

Assessing Nociception by fMRI of the Human Spinal Cord: A Systematic Review

OBJECTIVE

To assess the use of fMRI of the spinal cord in measuring noxious stimulation.

METHODS

The Scopus, Medline, EMBASE, and Web of Science databases were searched, along with the reference lists of included articles. Two independent reviewers screened abstracts, full-text articles, and extracted data. Original research was included if fMRI of the human spinal cord was used to measure responses to noxious stimulation.

RESULTS

Of the 192 abstracts screened, 19 met the search criteria and were divided according to their focus: investigating pain responses (n = 6), methodology (n = 6), spinal cord injury (n = 2), or cognition–pain interactions (n = 5). All but one study appear to have observed activity in ipsilateral and dorsal gray matter regions in response to noxious stimuli, although contralateral or ventral activity was also widely observed.

CONCLUSIONS

Although nociception can be investigated using spinal fMRI, establishing reliability, standardizing methodology, and reporting of results will greatly advance this field.

Genetic and neural correlates of romantic relationship satisfaction

Romantic relationship satisfaction (RRS) is important for mental/physical health but varies greatly across individuals. To date, we have known little about the biological (genetic and neural) correlates of RRS. We tested the hypothesis that the serotonin transporter promoter polymorphism (5-HTTLPR), the promoter region of the gene SLC6A4 that codes for the serotonin transporter protein, is associated with individuals' RRS. Moreover, we investigated neural activity that mediates 5-HTTLPR association with RRS by scanning short-short (s/s) and long-long (l/l) homozygotes of 5-HTTLPR, using functional MRI, during a Cyberball game that resulted in social exclusion. l/l compared with s/s allele carriers reported higher RRS but lower social interaction anxiety. l/l compared with s/s carriers showed stronger activity in the right ventral prefrontal cortex (RVPFC) and stronger functional connectivity between the dorsal and rostral ACC when being excluded from the Cyberball game. Moreover, the 5-HTTLPR association with RRS was mediated by the RVPFC activity and the 5-HTTLPR association with social interaction anxiety was mediated by both the dorsal-rostral ACC connectivity and RVPFC activity. Our findings suggest that 5-HTTLPR is associated with satisfaction of one's own romantic relationships and this association is mediated by the neural activity in the brain region related to emotion regulation.

Kinesthetic illusions attenuate experimental muscle pain, as do muscle and cutaneous stimulation

In the present study, muscle pain was induced experimentally in healthy subjects by administrating hypertonic saline injections into the tibialis anterior (TA) muscle. We first aimed at comparing the analgesic effects of mechanical vibration applied to either cutaneous or muscle receptors of the TA or to both types simultaneously. Secondly, pain alleviation was compared in subjects in whom muscle tendon vibration evoked kinesthetic illusions of the ankle joint. Muscle tendon vibration, which primarily activated muscle receptors, reduced pain intensity by 30% (p<0.01). In addition, tangential skin vibration reduced pain intensity by 33% (p<0.01), primarily by activating cutaneous receptors. Concurrently stimulating both sensory channels induced stronger analgesic effects (-51%, p<0.01), as shown by the lower levels of electrodermal activity. The strongest analgesic effects of the vibration-induced muscle inputs occurred when illusory movements were perceived (-38%, p=0.01). The results suggest that both cutaneous and muscle sensory feedback reduce muscle pain, most likely via segmental and supraspinal processes. Further clinical trials are needed to investigate these new methods of muscle pain relief.

The Impact of Simulated Nature on Patient Outcomes

Objective:

To examine whether incorporation of simulated nature, in the form of ceiling mounted photographic sky compositions, influences patient outcomes.

Background:

Previous studies have shown that most forms of nature exposure have a positive influence on patients. However, earlier studies have mostly focused on wall-hung nature representations. The emergence of simulated nature products has raised the question regarding the effects of the new product on patient outcomes.

Methods:

A between-subject experimental design was adopted, where outcomes from five inpatient rooms with sky composition ceiling fixture were compared to corresponding outcomes in five identical rooms without the intervention. Data were collected from a total of 181 subjects on 11 outcomes. Independent sample tests were performed to identify differences in mean outcomes.

Result:

Significant positive outcomes were observed in environmental satisfaction and diastolic blood pressure (BP). Environmental satisfaction in the experimental group was 12.4% higher than the control group. Direction of association for diastolic BP, nausea/indigestion medication, acute stress, anxiety, pain, and environmental satisfaction were consistent with a priori hypothesis. A post hoc exploratory assessment involving patients who did not self-request additional pain and sleep medication demonstrated confirmatory directions for all outcomes except Systolic BP, and statistically significant outcomes for Acute Stress and Anxiety—Acute Stress and Anxiety levels of the experimental group subjects was 53.4% and 34.79% lower, respectively, than that of the control group subjects.

Conclusion:

Salutogenic benefits of photographic sky compositions render them better than traditional ceiling tiles and offer an alternative to other nature interventions.

Subjective pain perception mediated by alpha rhythms

Suppression of spontaneous alpha oscillatory activities, interpreted as cortical excitability, was observed in response to both transient and tonic painful stimuli. The changes of alpha rhythms induced by pain could be modulated by painful sensory inputs, experimental tasks, and top-down cognitive regulations such as attention. The temporal and spatial characteristics, as well as neural functions of pain induced alpha responses, depend much on how these factors contribute to the observed alpha event-related desynchronization/synchronization (ERD/ERS). How sensory-, task-, and cognitive-related changes of alpha oscillatory activities interact in pain perception process is reviewed in the current study, and the following conclusions are made: (1) the functional inhibition hypothesis that has been proposed in auditory and visual modalities could be applied also in pain modality; (2) the neural functions of pain induced alpha ERD/ERS were highly dependent on the cortical regions where it is observed, e.g., somatosensory cortex alpha ERD/ERS in pain perception for painful stimulus processing; (3) the attention modulation of pain perception, i.e., influences on the sensory and affective dimensions of pain experience, could be mediated by changes of alpha rhythms. Finally, we propose a model regarding the determinants of pain related alpha oscillatory activity, i.e., sensory-discriminative, affective-motivational, and cognitive-modulative aspects of pain experience, would affect and determine pain related alpha oscillatory activities in an integrated way within the distributed alpha system.

EEG-Based Tonic Cold Pain Characterization Using Wavelet Higher Order Spectral Features

A novel approach in tonic cold pain characterization, based on electroencephalograph (EEG) data analysis using wavelet higher order spectral (WHOS) features, is presented here. The proposed WHOS-based feature space extends the relative power spectrum-based (phase blind) approaches reported so far a step forward; this is realized via dynamic monitoring of the nonlinerities of the EEG brain response to tonic cold pain stimuli by capturing the change in the underlying quadratic phase coupling at the bifrequency wavelet bispectrum/bicoherence domain due to the change of the pain level. Three pain characterization scenarios were formed and experimentally tested involving WHOS-based analysis of EEG data, acquired from 17 healthy volunteers that were subjected to trials of tonic cold pain stimuli. The experimental and classification analysis results, based on four well-known classifiers, have shown that the WHOS-based features successfully discriminate relax from pain status, provide efficient identification of the transition from relax to mild and/or severe pain status, and translate the subjective perception of pain to an objective measure of pain endurance. These findings seem quite promising and pave the way for adopting WHOS-based approaches to pain characterization under other types of pain, e.g., chronic pain and various clinical scenarios.

Effect of thermal stimulation on corticomotor excitability in patients with stroke

OBJECTIVE

This study examined the immediate effects of noxious and innocuous thermal stimulation intervention on corticomotor excitability for the paretic arm in patients with stroke.

DESIGN

Sixteen patients with stroke for more than 3 mos were randomly assigned into the experimental and control groups. All participants received the thermal stimulation protocol on the affected arm for 30 mins. The experimental group received noxious heat (46°C-47°C) and cold (7°C-8°C) stimuli, and the control group received innocuous heat (40°C-41°C) and cold (20°C-21°C) stimuli. Corticomotor excitability was assessed to measure the motor threshold, size of cortical motor output map, and mean motor evoked potentials for the abductor pollicis brevis by focal transcranial magnetic stimulation before and after 30 mins of thermal stimulation intervention program.

RESULTS

The findings of transcranial magnetic stimulation revealed a significant increase in map size of the affected hemisphere and mean motor evoked potentials in the experimental group. Moreover, significant differences in the change values of map size (7.0 [7.9] for the experimental group vs. -1.7 [2.9] for the control group, P = 0.03) and mean (SD) motor evoked potentials (0.4 [8.9] mV for the experimental group vs. -0.1 [0.1] mV for the control group, P = 0.03) were found.

CONCLUSIONS

The preliminary results suggest that the noxious 30 mins of thermal stimulation intervention induced neurophysiologic changes in the motor cortex of the lesioned hemisphere.

Altered cognition-related brain activity and interactions with acute pain in migraine

Little is known about the effect of migraine on neural cognitive networks. However, cognitive dysfunction is increasingly being recognized as a comorbidity of chronic pain. Pain appears to affect cognitive ability and the function of cognitive networks over time, and decrements in cognitive function can exacerbate affective and sensory components of pain. We investigated differences in cognitive processing and pain–cognition interactions between 14 migraine patients and 14 matched healthy controls using an fMRI block-design with two levels of task difficulty and concurrent heat (painful and not painful) stimuli. Across groups, cognitive networks were recruited in response to a difficult cognitive task, and a pain–task interaction was found in the right (contralateral to pain stimulus) posterior insula (pINS), such that activity was modulated by decreasing the thermal pain stimulus or by engaging the difficult cognitive task. Migraine patients had less task-related deactivation within the left dorsolateral prefrontal cortex (DLPFC) and left dorsal anterior midcingulate cortex (aMCC) compared to controls. These regions have been reported to have decreased cortical thickness and cognitive-related deactivation within other pain populations, and are also associated with pain regulation, suggesting that the current findings may reflect altered cognitive function and top-down regulation of pain. During pain conditions, patients had decreased task-related activity, but more widespread task-related reductions in pain-related activity, compared to controls, suggesting cognitive resources may be diverted from task-related to pain-reduction-related processes in migraine. Overall, these findings suggest that migraine is associated with altered cognitive-related neural activity, which may reflect altered pain regulatory processes as well as broader functional restructuring.

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Migraine patients had blunted task-related deactivations in DLPFC, aMCC, and cerebellum in the absence of pain, vs. controls.

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Unlike in healthy controls, these task-related deactivations were not modulated by the presence of an acute pain stimulus.

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Migraine patients had less task-related activity during pain, compared to controls.

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Acute pain disturbs cognitive processing more in patients than controls.

Distinct brain systems mediate the effects of nociceptive input and self-regulation on pain

Two distinct parallel neural systems independently contribute to our overall experience of pain – separately modulated by noxious input and by cognitive self-regulation.

Cognitive self-regulation can strongly modulate pain and emotion. However, it is unclear whether self-regulation primarily influences primary nociceptive and affective processes or evaluative ones. In this study, participants engaged in self-regulation to increase or decrease pain while experiencing multiple levels of painful heat during functional magnetic resonance imaging (fMRI) imaging. Both heat intensity and self-regulation strongly influenced reported pain, but they did so via two distinct brain pathways. The effects of stimulus intensity were mediated by the neurologic pain signature (NPS), an a priori distributed brain network shown to predict physical pain with over 90% sensitivity and specificity across four studies. Self-regulation did not influence NPS responses; instead, its effects were mediated through functional connections between the nucleus accumbens and ventromedial prefrontal cortex. This pathway was unresponsive to noxious input, and has been broadly implicated in valuation, emotional appraisal, and functional outcomes in pain and other types of affective processes. These findings provide evidence that pain reports are associated with two dissociable functional systems: nociceptive/affective aspects mediated by the NPS, and evaluative/functional aspects mediated by a fronto-striatal system.

Does cognitive self-regulation influence pain experience by affecting the primary representations of painful (nociceptive) stimuli in the brain? Or does it regulate reported pain via a neural pathway that is distinct from the one that mediates nociceptive pain? The present study demonstrates that nociceptive and cognitive manipulations of pain influence two distinct, separable neural systems, which operate together to construct the pain experience. The neurologic pain signature (NPS) mediates the effects of noxious input, whereas a fronto-striatal pathway connecting nucleus accumbens and ventromedial prefrontal cortex mediates the effects of cognitive self-regulation of pain. These findings help move the field beyond the “one system” view of pain as a primarily nociceptive process, and provide a foundation for new approaches to multidimensional pain assessment and treatment.

When pain is not only pain: inserting needles into the body evokes distinct reward-related brain responses in the context of a treatment

The aim of this study was to compare behavioral and functional brain responses to the act of inserting needles into the body in two different contexts, treatment and stimulation, and to determine whether the behavioral and functional brain responses to a subsequent pain stimulus were also context dependent. Twenty-four participants were randomly divided into two groups: an acupuncture treatment (AT) group and an acupuncture stimulation (AS) group. Each participant received three different types of stimuli, consisting of tactile, acupuncture, and pain stimuli, and was given behavioral assessments during fMRI scanning. Although the applied stimuli were physically identical in both groups, the verbal instructions differed: participants in the AS group were primed to consider the acupuncture as a painful stimulus, whereas the participants in the AT group were told that the acupuncture was part of therapeutic treatment. Acupuncture yielded greater brain activation in reward-related brain areas (ventral striatum) of the brain in the AT group when compared to the AS group. Brain activation in response to pain stimuli was significantly attenuated in the bilateral secondary somatosensory cortex and the right dorsolateral prefrontal cortex after prior acupuncture needle stimulation in the AT group but not in the AS group. Inserting needles into the body in the context of treatment activated reward circuitries in the brain and modulated pain responses in the pain matrix. Our findings suggest that pain induced by therapeutic tools in the context of a treatment is modulated differently in the brain, demonstrating the power of context in medical practice.

Involvement of the endocannabinoid system in attentional modulation of nociceptive behaviour in rats

BACKGROUND

Distraction is used clinically to relieve and manage pain. It is hypothesized that pain demands attention and that exposure to another attention-demanding stimulus causes withdrawal of attention away from painful stimuli, thereby reducing perceived pain. We have recently developed a rat model that provides an opportunity to investigate the neurobiological mechanisms mediating distraction-induced analgesia, as these mechanisms are, at present, poorly understood. Given the well-described role of the endogenous cannabinoid (endocannabinoid; EC) system in the modulation of pain and attentional processing, the present study investigated its role in distraction-induced antinociception in rats.

METHODS

Animals received the CB1 receptor antagonist/inverse agonist, rimonabant or vehicle intraperitoneally, 30 min prior to behavioural evaluation. Formalin-evoked nociceptive behaviour was measured in the presence or absence of a novel-object distractor. Liquid chromatography-tandem mass spectrometry was used to determine the levels of the endogenous cannabinoids anandamide and 2-arachidonoylglycerol (2-AG) in the ventral hippocampus (vHip).

RESULTS

Exposure to a novel object distractor significantly reduced formalin-evoked nociceptive behaviour. The novel object-induced reduction in nociceptive behaviour was attenuated by rimonabant. Novel object exposure was also associated with increased tissue levels of anandamide and 2-AG in the vHip.

CONCLUSIONS

These data suggest that the reduction in formalin-evoked nociceptive behaviour that occurs as a result of exposure to a novel object may be mediated by engagement of the EC system, in particular in the vHip. The results provide evidence that the EC system may be an important neural substrate subserving attentional modulation of pain.

Effects of stress and relaxation on pain perception in subjects with pain-free occlusional disharmony compared with healthy controls

OBJECTIVES

The significance of occlusal disharmony for the development of painful temporomandibular disorder (TMD) is controversial. The ongoing biomechanical strain caused by occlusal disharmony might lead to sensitization processes in the nociceptive system. Understanding these processes might be an important step toward understanding the possible relationship between occlusal disharmony and TMD. In this study, we therefore investigated whether subjects with occlusal disharmony (n = 22) differ from healthy controls (n = 26) in their pain perception and pain modulation by stress and relaxation.

MATERIALS AND METHODS

Trigeminal and extratrigeminal experimental pain perception (pinprick, heat, and pressure pain) was assessed before and after stress (mental arithmetic) and relaxation (viewing of low-arousal pictures).

RESULTS

There were no group differences in pain perception at baseline or during the stress task. Compared with controls, the occlusal disharmony group exhibited an inadequate reduction in pain perception during relaxation, which was significant for the extratrigeminal site (P < 0.01) and reached a trend for significance at the trigeminal site (P = 0.1).

CONCLUSIONS

These results suggest that subjects with occlusal disharmony show signs of disturbed endogenous pain inhibition during relaxation.

CLINICAL RELEVANCE

There is evidence for the presence of sensitization of the nociceptive system in subjects with occlusal disharmony. Possibly, deficient inhibition of extratrigeminal and trigeminal pain perception by relaxation might contribute to the development of TMD or other chronic pain disorders.

Fibromyalgia patients had normal distraction related pain inhibition but cognitive impairment reflected in caudate nucleus and hippocampus during the Stroop Color Word Test

The mechanisms causing cognitive problems in chronic pain patients are not well understood. We used the Stroop color word task (SCWT) to investigate distraction-induced analgesia, cognitive performance, and cerebral activation patterns in 29 fibromyalgia (FM) patients (mean age 49.8 years, range 25–64 years) and 31 healthy controls (HC) (mean age 46.3 years, range 20–63 years). In the first study, SCWT was used to investigate distraction-induced analgesia in FM patients. Two versions of the task were applied, one with only congruent color-word images and one with incongruent images. Pressure pain thresholds were assessed using a pressure algometer before, during, and following SCWT. In the second study, reaction times (RTs) were assessed and functional magnetic resonance imaging (fMRI) was used to investigate cerebral activation patterns in FM patients and HC during the SCWT. An event-related task mixing incongruent and congruent images was used. In study one, we found reduced pressure pain sensitivity during SCWT in both groups alike and no statistically significant differences were seen between the incongruent and congruent conditions. The study two revealed longer RTs during the incongruent compared to the congruent condition in both groups. FM patients had longer RTs than HC in both conditions. Furthermore, we found a significant interaction between group and congruency; that is, the group differences in RTs were more pronounced during the incongruent condition. This was reflected in a reduced activation of the caudate nucleus, lingual gyrus, temporal areas, and the hippocampus in FM patients compared to HC. In conclusion, we found normal pain inhibition during SWTC in FM patients. The cognitive difficulties seen in FM patients, reflected in longer RTs, were related to reduced activation of the caudate nucleus and hippocampus during incongruent SCWT, which most likely affected the mechanisms of cognitive learning in FM patients.

Altered brain response to others׳ pain in major depressive disorder

BACKGROUND

Empathy has a central role in successful interpersonal engagement. Several studies have reported altered empathy in major depressive disorder (MDD), which could lead to interpersonal difficulties. However, the neural basis of altered empathy in the disorder is still largely unknown. To address this, we performed functional magnetic resonance imaging that tested empathy for others׳ pain in MDD patients.

METHODS

Eleven patients with MDD and 11 age-, gender-, handedness-, and education level-matched healthy control subjects were studied. We compared MDD patients and healthy controls for their regional hemodynamic responses to visual perception of videos showing human hands in painful situations. We also assessed subjective pain ratings of the videos in each group.

RESULTS

The MDD patients showed lower pain ratings for the painful videos compared with the healthy controls. In addition, the MDD patients showed reduced cerebral activation in the left middle cingulate cortex, and the right somatosensory-related cortices, whereas they showed greater cerebral activation in the left inferior frontal gyrus.

LIMITATIONS

We relied on a relatively small sample size and could not exclude effects of medications.

CONCLUSIONS

These results suggest that in MDD patients the altered neural activations in these regions may be associated with a deficit in the identification of pain in others. This study adds to our understanding of the neural mechanism involved in empathy in MDD.

Intra-periaqueductal gray infusion of zeta inhibitory peptide attenuates pain-conditioned place avoidance in rats

Pain is a complex experience that made up of sensory, emotional and cognitive dimensions, and the emotional factors have an important influence on intensity of pain perception. The role of periaqueductal gray (PAG) in sensory component of pain has been extensively studied, while data about pain affect are quite limited. Using formalin-induced conditioned place avoidance (F-CPA) test and inflammatory pain model, present study investigated the effect of intra-PAG infusion of zeta inhibitory peptide (ZIP) on noxious stimulation induced aversion, and the sensory component of pain. Intra-PAG injection of ZIP is sufficient to disrupt pain-induced aversion, but the ZIP infusion did not change inflammation induced pain hypersensitivity in rats. These findings suggest that PAG contributes to pain-related aversion in rats, and the mechanism of pain emotion encoding in PAG may attribute to the activation of targets of ZIP.

Cortical EEG alpha rhythms reflect task-specific somatosensory and motor interactions in humans

Anticipating sensorimotor events allows adaptive reactions to environment with crucial implications for self-protection and survival. Here we review several studies of our group that aimed to test the hypothesis that the cortical processes preparing the elaboration of sensorimotor interaction is reflected by the reduction of anticipatory electroencephalographic alpha power (about 8-12Hz; event-related desynchronization, ERD), as an index that regulate task-specific sensorimotor processes, accounted by high-alpha sub-band (10-12Hz), rather than a general tonic alertness, accounted by low-alpha sub-band (8-10Hz). In this line, we propose a model for human cortical processes anticipating warned sensorimotor interactions. Overall, we reported a stronger high-alpha ERD before painful than non-painful somatosensory stimuli that is also predictive of the subjective evaluation of pain intensity. Furthermore, we showed that anticipatory high-alpha ERD increased before sensorimotor interactions between non-painful or painful stimuli and motor demands involving opposite hands. In contrast, sensorimotor interactions between painful somatosensory and sensorimotor demands involving the same hand decreased anticipatory high-alpha ERD, due to a sort of sensorimotor "gating" effect. In conclusion, we suggest that anticipatory cortical high-alpha rhythms reflect the central interference and/or integration of ascending (sensory) and descending (motor) signals relative to one or two hands before non-painful and painful sensorimotor interactions.

Painful cutaneous laser stimuli induce event-related oscillatory EEG activities that are different from those induced by nonpainful electrical stimuli

The non-phase-locked EEG response to painful stimuli has usually been characterized as decreased oscillatory activity (event-related desynchronization, ERD) in the alpha band. Increased activity (event-related synchronization, ERS) in the gamma band has been reported more recently. We have now tested the hypothesis that the non-phase-locked responses to nonpainful electric cutaneous stimuli are different from those to painful cutaneous laser stimuli when the baseline salience of the two stimuli is the same and the salience during the protocol is modulated by count laser and count electric tasks. Both of these stimuli were presented in random order in a single train at intensities that produced the same baseline salience in the same somatic location. The response to the laser stimulus was characterized by five windows (designated windows I-V) in the time-frequency domain: early (200-400 ms) and late (600-1,400 ms) delta/theta ERS, 500-900 ms alpha ERD, 1,200-1,600 ms beta ERS (rebound), and 800-1,200 ms gamma ERS. Similar ERS/ERD windows of activity were found for the electric stimulus. Individual participants very commonly had activity in windows consistent with the overall analysis. Linear regression of ERS/ERD for parietal channels was most commonly found for sensory (pain or unpleasantness)- or attention (salience)-related measures. Overall, the main effect for modality was found in window I-delta/theta and window V-gamma, and the Modality with Task interaction was found in all five windows. All significant interaction terms included Modality as a factor. Therefore, Modality was the most common factor explaining our results, which is consistent with our hypothesis.

Neural correlates of nature stimuli: an FMRI study

OBJECTIVE

Examine whether there are unique patterns of brain activation associated with exposure to photographic sky compositions (representing nature stimuli) as compared with other positive, negative, and neutral images.

BACKGROUND

The positive impact of nature images on health outcomes traditionally has been measured using behavioral and physiological indicators. However, there is a lack of understanding of the underlying neural mechanism that explains this positive influence.

METHODS

A combination of behavioral responses and functional magnetic resonance imaging (fMRI) technology was used to address research questions. Ten participants belonging to five age groups were subjected to short (25 seconds) exposures of 32 images while their brain activation was monitored via the BOLD response. In a separate run, participants were subjected to extended exposures (12 minutes) of a sky composition and an image of a traditional ceiling.

RESULTS

The results show that the activation patterns produced by sky compositions and positive images were quite similar as compared to negative or neutral images. However, sky compositions also produced some unique areas of activation, including those associated with spatial cognition, the expanse of space, circadian rhythm, and perceived motion. In the extended exposure condition, sky compositions tended to activate regions associated with dreaming, while traditional ceiling images activated regions that are related to face processing and potentially visual hallucinations.

CONCLUSIONS

Nature stimuli, with a combination of vegetation and sky, may produce unique beneficial effects not present in general positive stimuli.

KEYWORDS

Evidence-based design, hospital, healing environments, outcomes, patient-centered care.

Evaluation of the effectiveness of pregabalin in alleviating pain associated with fibromyalgia: using functional magnetic resonance imaging study

Purpose

To assess the efficacy of pregabalin by showing differences in the neuronal activities of fibromyalgia (FM) patients before and after longitudinal treatment using functional magnetic resonance imaging (fMRI).

Materials and Methods

In total, 21 female patients with FM and 11 age- and gender-matched healthy controls participated. FM patients underwent fMRI at baseline and following pharmacological therapy with pregabalin to diminish their pain. Pressure-pain stimuli were delivered on the subject’s thumbnail bed during fMRI scans. Brain activation regions in fMRI were evaluated for longitudinal changes using a paired t-test. Changes in clinical features were also assessed with the Fibromyalgia Impact Questionnaire (FIQ), Brief Fatigue Inventory (BFI), Beck Depression Inventory (BDI), Widespread Pain Index (WPI), Symptom Severity Scale Score (SSS), and State-Trait Anxiety Inventory (STAI).

Results

Clinical scores were reduced significantly following therapy with five of the six clinical tests (FIQ, BFI, BDI, WPI, SSS; p < 0.05). Brain activation post-treatment was significantly lower than that pre-treatment in 13 regions of the brain (p < 0.001).

Conclusions

Our findings confirm that pregabalin influences aspects of the whole pain matrix, using fMRI, inducing longitudinal changes in neuronal activity during the pain state, and that it reduces pain and other core symptoms of FM. This method could be applied to other longitudinal clinical trials of pharmacological treatments for FM.

Thicker posterior insula is associated with disease duration in women with irritable bowel syndrome (IBS) whereas thicker orbitofrontal cortex predicts reduced pain inhibition in both IBS patients and controls

Patients with irritable bowel syndrome (IBS) are affected by chronic abdominal pain and show decreased pain inhibition. Moreover, they exhibit differences in brain morphology compared with healthy volunteers. The aim of this study was to examine whether decreased pain inhibition is associated with altered brain morphology in IBS patients. Structural magnetic resonance imaging scans were acquired in 14 female patients with diarrhea-predominant IBS and 14 controls. Pain and anxiety modulation were characterized using electrical stimulation of the sural nerve and heterotopic noxious counterstimulation. IBS patients reported decreased pain inhibition (P = .02) as well as increased shock anxiety, pain catastrophizing, depressive symptoms, and trait anxiety (P's ≤ .05). IBS patients also showed a thicker right posterior insula (pINS), associated with longer IBS duration (r = .67, P = .02). In addition, thicker right lateral orbitofrontal cortex was strongly associated with less pain inhibition in both IBS patients (r = .70, P = .02) and controls (r = .68, P = .01). Results are consistent with the role of the insula in interoception and pain and suggest that IBS may induce thickening of the pINS. Reduced pain inhibition may further involve a modification of the regulatory influence of the orbitofrontal cortex on pain-related processes.

PERSPECTIVE

This study investigated the brain morphology of IBS patients. IBS patients showed thicker right pINS, associated with longer disease duration but not with psychological symptoms. This suggests that IBS induces thickening of pINS, which may contribute to its pathophysiology, consistent with the role of the pINS in interoception and pain.

Neural underpinnings of behavioural strategies that prioritize either cognitive task performance or pain

We previously discovered that when faced with a challenging cognitive task in the context of pain, some people prioritize task performance, while in others, pain results in poorer performance. These behaviours, designated respectively as A- and P-types (for attention dominates vs pain dominates), may reflect pain coping strategies, resilience or vulnerabilities to develop chronic pain, or predict the efficacy of treatments such as cognitive behavioural therapy. Here, we used a cognitive interference task and pain stimulation in 80 subjects to interrogate psychophysical, psychological, brain structure and function that distinguish these behavioural strategies. During concurrent pain, the A group exhibited faster task reaction times (RTs) compared to nonpain trials, whereas the P group had slower RTs during pain compared to nonpain trials, with the A group being 143 ms faster than the P group. Brain imaging revealed structural and functional brain features that characterized these behavioural strategies. Compared to the performance-oriented A group, the P group had (1) more gray matter in regions implicated in pain and salience (anterior insula, anterior midcingulate cortex, supplementary motor area, orbitofrontal cortex, thalamus, caudate), (2) greater functional connectivity in sensorimotor and salience resting-state networks, (3) less white matter integrity in the internal and external capsule, anterior thalamic radiation and corticospinal tract, but (4) were indistinguishable based on sex, pain sensitivity, neuroticism, and pain catastrophizing. These data may represent neural underpinnings of how task performance vs pain is prioritized and provide a framework for developing personalized pain therapy approaches that are based on behaviour-structure-function organization.

The influence of working memory capacity on experimental heat pain

Pain processing and attention have a bidirectional interaction that depends upon one's relative ability to use limited-capacity resources. However, correlations between the size of limited-capacity resources and pain have not been evaluated. Working memory capacity, which is a cognitive resource, can be measured using the reading span task (RST). In this study, we hypothesized that an individual's potential working memory capacity and subjective pain intensity are related. To test this hypothesis, we evaluated 31 healthy participants' potential working memory capacity using the RST, and then applied continuous experimental heat stimulation using the listening span test (LST), which is a modified version of the RST. Subjective pain intensities were significantly lower during the challenging parts of the RST. The pain intensity under conditions where memorizing tasks were performed was compared with that under the control condition, and it showed a correlation with potential working memory capacity. These results indicate that working memory capacity reflects the ability to process information, including precise evaluations of changes in pain perception.

PERSPECTIVE

In this work, we present data suggesting that changes in subjective pain intensity are related, depending upon individual potential working memory capacities. Individual working memory capacity may be a phenotype that reflects sensitivity to changes in pain perception.

Effects of preceding stimulation on brain activation in response to colonic distention in humans

OBJECTIVE

It has been suggested that the pattern of distension (moderate following mild and vice versa) might influence brain activation and the experience of hypersensitivity, offset analgesia, and anticipation. Nevertheless, how the pattern of stimulation affects sensitization and/or desensitization to visceral stimulation remains unknown.

METHODS

In 45 nonclinical healthy participants (12 women, 33 men; 20-26 years old), brain processing of visceral sensation induced by colonic distension was examined using H2(15)O positron emission tomography. Subjective feelings regarding the stimuli were also measured. The descending colon was stimulated using six patterns of three bag pressures (0, 20, and 40 mm Hg). To evaluate the neural sensitization to visceral stimulation arising from the precedence effect, the effects of a 20- or 40-mm Hg distention after a sham or 20- or 40-mm Hg distension were analyzed using statistical parametric mapping. The level of significance was set at a voxelwise level of p < .0001, with cluster extent sizes of k > 50.

RESULTS

The midbrain, insula, and cerebellum, were more strongly activated by a 20-mm Hg distension with a preceding 40-mm Hg distention than by a 20-mm Hg distention without a preceding stimulation (p < .0001). Conversely, a sham stimulation after the experience of an intense stimulation activated the midcingulate cortex, compared with a sham stimulation without the experience of actual visceral stimulation (p < .0001).

CONCLUSIONS

By directly comparing different patterns of visceral stimuli, preceding visceral stimuli may affect neural sensitization and/or desensitization in humans, including elevated midbrain, insula, and midcingulate cortex.

Cognitive and emotional control of pain and its disruption in chronic pain

Chronic pain is one of the most prevalent health problems in our modern world, with millions of people debilitated by conditions such as back pain, headache and arthritis. To address this growing problem, many people are turning to mind-body therapies, including meditation, yoga and cognitive behavioural therapy. This article will review the neural mechanisms underlying the modulation of pain by cognitive and emotional states - important components of mind-body therapies. It will also examine the accumulating evidence that chronic pain itself alters brain circuitry, including that involved in endogenous pain control, suggesting that controlling pain becomes increasingly difficult as pain becomes chronic.

Reduced Frontal P3a Amplitude in Migraine Patients during the Pain-Free Period

BACKGROUND AND PURPOSE

Neuropsychological and neuroimaging studies both suggest that frontal lobe dysfunction is present in migraineurs. Since P3a abnormalities manifest in other diseases associated with attention problems, such as attention deficit hyperactivity disorder, we hypothesized that migraine patients have P3a abnormalities, particularly in the frontal region.

METHODS

Event-related potentials were measured using a passive auditory oddball paradigm in 16 female migraineurs (aged 22.9±2.0 years, mean±SD) during the interictal period and in 16 age-matched healthy females (22.6±2.0 years). The amplitudes and latencies were analyzed independently using repeated-measures analysis of variance. Nonparametric statistical testing using a cluster-level randomization method was performed to localize the abnormalities.

RESULTS

The mean P3a amplitude at frontal areas during the third trials was significantly lower in migraineurs (1.06 µV) than in controls (1.69 µV, p=0.026). P3a amplitudes were negatively correlated with the duration of the migraine history (r=-0.618, p=0.014). Cluster-based nonparametric statistical analysis showed that the amplitudes over left frontal areas were significantly lower in migraine patients than in controls.

CONCLUSIONS

A reduced P3a amplitude of migraineurs reflects attentional deficits and frontal dysfunction. The negative correlation between P3a amplitude and the duration of the migraine history suggests that attentional deficits and frontal dysfunction are either the cause or the result of headache.