Central Executive and Default Mode Network Intranet work Functional Connectivity Patterns in Chronic Migraine

Revealing multiple biological subtypes of schizophrenia through a data-driven approach

INTRODUCTION

The brain imaging subtypes of schizophrenia have been widely investigated using data-driven approaches. However, the heterogeneity of SZ in multiple biological data is largely unknown.

METHODS

A data-driven model was used to classify brain imaging, gut microbiota, and brain-gut fusion data obtained through a dot product fusion method, identifying significant subtypes and calculating their correlations with clinical symptoms and cognitive performance.

RESULTS

These subtypes remain relatively independent and demonstrate typical features and biomarkers, which are significantly associated with clinical symptoms and cognitive performance. Two brain subtypes with opposite structural and functional changes are identified: (1) a structural variant-dominant brain subtype with negative symptoms and cognitive deficits and (2) a functional alteration-dominant brain subtype with positive symptoms. The three gut subtypes include the following: (1) Collinsella-dominant; (2) Prevotella-dominant with positive symptoms; and (3) Streptococcus-dominant. Two brain-gut subtypes show different abnormalities in brain‒genus linkages: (1) strong connectivity of "brain function in the temporal and parietal lobes-Prevotella" with reduced attention scores and (2) strong connectivity of "brain structure and function in the frontal and parietal lobes-multiple genera" with positive symptoms. Notably, brain subtypes and brain-gut subtypes are most relevant to clinical symptoms, whereas gut subtypes reveal more cognitive biomarkers.

CONCLUSION

These findings show the potential to identify multiple biological subtypes with distinct biomarkers, thereby suggesting the possibility of personalized and precise treatment for SZ patients.

Imaging Brain Networks: Insights into Mechanisms of Temporomandibular Disorders

Temporomandibular disorders are a group of craniomaxillofacial disorders mainly characterized by pain and motor dysfunction of the temporomandibular joints and surrounding masticatory muscles. Clinically, patients with temporomandibular disorders often display central nervous system dysfunction, such as negative mood disorders, but the underlying cause remains unclear. Recent developments in neuroimaging techniques have facilitated new understanding. Notably, the triple network model consisting of the default mode network, the central executive network, and the salience network is of particular interest in this regard and may provide new insights into brain network alterations. Specifically, we observed that patients with temporomandibular disorders have abnormal activation of attention-related brain regions in the default mode network, which may be related to pain rumination. In addition, cortical atrophy and altered functional connectivity were found in regions related to the regulation of emotion and pain. In the central executive network, decreased activity and metabolism were seen in pain regulation regions, while abnormal activation occurred in regions associated with negative emotions. The salience network showed aberrant activation and metabolic changes in pain perception regions, and negative emotions were associated with an abnormal activation pattern. Potentially treatment-induced changes included a return to normal activity in attention and emotion regulation regions, suggesting that assessing activity in these networks may be used to evaluate treatment efficacy. Finally, this review highlights current dilemmas and future opportunities for the field in terms of research cohorts, methods, scope, and analytical techniques. Further exploration is necessary to realize a better understanding of the neuropathophysiology of temporomandibular disorders and ultimately more effective treatments.

Reduced oxygen supply to the prefrontal cortex during the Stroop task in migraine patients with aura: A preliminary functional near-infrared spectroscopy study

The role of the cerebrovascular system in migraine pathogenesis is critical. Several studies have demonstrated alterations in the regional cerebral blood flow that persist during headache-free intervals. In the present study, we aimed to measure the prefrontal hemodynamic responses to the cognitive task in interictal episodic migraineurs. We enrolled eight migraine patients with aura (mean age 25.75 ± 4.39 years), twelve migraine patients without aura (mean age 28.25 ± 6.59 years), and eleven age- and education-matched healthy subjects. We employed the Victoria Stroop task to assess executive functions, specifically selective attention and inhibitory control. The mean changes in the oxy-Hb, deoxy-Hb and total Hb concentrations during the Stroop interference (incongruent minus neutral) were recorded by functional near-infrared spectroscopy (fNIRS). Our preliminary results indicated that migraine patients with aura had higher reaction time (p = 0.033) and lower prefrontal oxy-Hb activity (p = 0.036) during the Stroop interference compared to healthy subjects. For the left lateral prefrontal cortex, migraine with aura group showed lower oxy-Hb activity than the healthy subjects during the Stroop interference (p = 0.009). However, there were no such differences in the right lateral prefrontal cortex. Additionally, we found a relationship between prefrontal oxygenation and the severity of headaches, the frequency of attacks, and the number of monthly migraine days. We noticed a decrease in prefrontal blood flow in migraine patients with aura, even during the interictal periods. This may indicate that migraine with aura could be a persistent neurovascular uncoupling disorder. Moreover, the reduced oxygen supply to the prefrontal cortex may be associated with impaired frontal lobe functions.

The neurosociological paradigm of the metaverse

Metaverse integrates people into the virtual world, and challenges depend on advances in human, technological, and procedural dimensions. Until now, solutions to these challenges have not involved extensive neurosociological research. The study explores the pioneering neurosociological paradigm in metaverse, emphasizing its potential to revolutionize our understanding of social interactions through advanced methodologies such as hyperscanning and interbrain synchrony. This convergence presents unprecedented opportunities for neurotypical and neurodivergent individuals due to technology personalization. Traditional face-to-face, interbrain coupling, and metaverse interactions are empirically substantiated. Biomarkers of social interaction as feedback between social brain networks and metaverse is presented. The innovative contribution of findings to the broader literature on metaverse and neurosociology is substantiated. This article also discusses the ethical aspects of integrating the neurosociological paradigm into the metaverse.

[Identification of Differences in Brain Functions at Varied Degrees of Acclimatization to High Altitudes Based on Resting-State Electroencephalogram Signals]

Objective

To explore the differences in brain functions between individuals with good acclimatization to high altitudes and those with poor acclimatization based on microstate and functional connectivity analysis of resting-state electroencephalogram (EEG) activities.

Methods

A total of 44 residents exposed to the high-altitude environment of 3650 m above sea level were enrolled. They were divided into two groups according to their findings for the high-altitude acclimatization index (AAI), with 22 in the good acclimatization group and 22 in the poor acclimatization group. The good acclimatization group had 10 males and 12 females of the mean age of (20.48±2.09) years. Among them, 10 were Tibetans, and 12 were Han Chinese. The poor acclimatization group consisted of 18 males and 4 females, with a mean age of (18.90±1.25) years. Among them, 7 were Tibetans, and 15 were Han Chinese. The K-means clustering algorithm was used to classify EEG microstates into four categories of A, B, C, and D. The average duration, coverage, occurrence frequency, and transition probabilities between microstates were compared. Coherence analysis (COH) was performed to assess the strength of brain network connectivity.

Results

Compared to the good acclimatization group, the poor acclimatization group exhibited a longer duration, higher occurrence frequency, and coverage of microstate C. The coverage of microstate D was also higher, while the occurrence frequency and coverage of microstate B were lower. The poor acclimatization group showed a decrease in transitions from microstate B to A or D, while transitions from C to B or D, and those from D to A or C increased, showing statistically significant differences between the groups (P<0.05). In the α, β, δ, and θ frequency bands, the poor acclimatization group had higher COH strength in regions such as the frontal and occipital lobes, showing symmetrical functional connectivity between the left and right hemispheres.

Conclusion

The good and poor high-altitude acclimatization groups exhibit different neural mechanisms in terms of microstates and functional connectivity. There are significant differences between individuals with good acclimatization and those with poor acclimatization regarding visual information processing, interference resistance, brain network stability, and coherence.

Cortical structural network characteristics in non-cognitive impairment end-stage renal disease

Objective

Explore alterations in topological features of gray matter volume (GMV) and structural networks in non-cognitive impairment end-stage renal disease (Non-CI ESRD).

Materials and methods

Utilizing graph theory, we collected structural magnetic resonance imaging (sMRI) data from 38 Non-CI ESRD patients and 50 normal controls (NC). We compared, and extracted the GMV across subject groups, constructed corresponding structural covariance networks (SCNs), and investigated the alterations in SCNs feature parameters between groups.

Results

In Non-CI ESRD patients, The GMV were reduced in several brain regions, predominantly on the left side (p < 0.05, FWE correction). The small-world network characteristics of the patient group's brain networks showed a tendency toward regular. In a few densities, global network parameters, transitivity, (p < 0.05) was significantly increased in the ESRD group. Regional network measurements revealed inconsistent changes in regional efficiency across different brain areas. In the analysis of network hubs, the right temporal pole is likely a compensatory hub for Non-CI ESRD patients. The SCNs in Non-CI ESRD patients demonstrated reduced topological stability against targeted attacks.

Conclusion

This study reveals that patients with renal failure exhibited subtle changes in brain network characteristics even before a decline in cognitive scores. These changes involve compensatory activation in certain brain regions, which enhances network transitivity to maintain the efficiency of whole-brain network information integration without significant loss. Additionally, the SCNs characteristics can serve as a neuroanatomical marker for brain alterations in Non-CI ESRD patients, offering new insights into the mechanisms of early brain injury in ESRD patients.

Analyzing the topological properties of resting-state brain function network connectivity based on graph theoretical methods in patients with high myopia

AIM

Recent imaging studies have found significant abnormalities in the brain's functional or structural connectivity among patients with high myopia (HM), indicating a heightened risk of cognitive impairment and other behavioral changes. However, there is a lack of research on the topological characteristics and connectivity changes of the functional networks in HM patients. In this study, we employed graph theoretical analysis to investigate the topological structure and regional connectivity of the brain function network in HM patients.

METHODS

We conducted rs-fMRI scans on 82 individuals with HM and 59 healthy controls (HC), ensuring that the two groups were matched for age and education level. Through graph theoretical analysis, we studied the topological structure of whole-brain functional networks among participants, exploring the topological properties and differences between the two groups.

RESULTS

In the range of 0.05 to 0.50 of sparsity, both groups demonstrated a small-world architecture of the brain network. Compared to the control group, HM patients showed significantly lower values of normalized clustering coefficient (γ) (P = 0.0101) and small-worldness (σ) (P = 0.0168). Additionally, the HM group showed lower nodal centrality in the right Amygdala (P < 0.001, Bonferroni-corrected). Notably, there is an increase in functional connectivity (FC) between the saliency network (SN) and Sensorimotor Network (SMN) in the HM group, while the strength of FC between the basal ganglia is relatively weaker (P < 0.01).

CONCLUSION

HM Patients exhibit reduced small-world characteristics in their brain networks, with significant drops in γ and σ values indicating weakened global interregional information transfer ability. Not only that, the topological properties of the amygdala nodes in HM patients significantly decline, indicating dysfunction within the brain network. In addition, there are abnormalities in the FC between the SN, SMN, and basal ganglia networks in HM patients, which is related to attention regulation, motor impairment, emotions, and cognitive performance. These findings may provide a new mechanism for central pathology in HM patients.

Individualized prediction of cognitive test scores from functional brain connectome in patients with first-episode late-life depression

BACKGROUND

In the realm of cognitive screening, the Mini-Mental State Examination (MMSE) and the Montreal Cognitive Assessment (MoCA) are widely utilized for detecting cognitive deficits in patients with late-life depression (LLD), However, the interindividual variability in neuroimaging biomarkers contributing to individual-specific symptom severity remains poorly understood. In this study, we used a connectome-based predictive model (CPM) approach on resting-state functional magnetic resonance imaging data from patients with LLD to establish individualized prediction models for the MoCA and the MMSE scores.

METHODS

We recruited 135 individuals diagnosed with first-episode LLD for this research. Participants underwent the MMSE and MoCA tests, along with resting-state functional magnetic resonance imaging scans. Functional connectivity matrices derived from these scans were utilized in CPM models to predict MMSE or MoCA scores. Predictive precision was assessed by correlating predicted and observed scores, with the significance of prediction performance evaluated through a permutation test.

RESULTS

The negative model of the CPM procedure demonstrated a significant capacity to predict MoCA scores (r = -0.309, p = 0.002). Similarly, the CPM procedure could predict MMSE scores (r = -0.236, p = 0.016). The predictive models for cognitive test scores in LLD primarily involved the visual network, somatomotor network, dorsal attention network, and ventral attention network.

CONCLUSIONS

Brain functional connectivity emerges as a promising predictor of personalized cognitive test scores in LLD, suggesting that functional connectomes are potential neurobiological markers for cognitive performance in patients with LLD.

Enhancing Speech Rehabilitation in a Young Adult with Trisomy 21: Integrating Transcranial Direct Current Stimulation (tDCS) with Rapid Syllable Transition Training for Apraxia of Speech

Apraxia of speech is a persistent speech motor disorder that affects speech intelligibility. Studies on speech motor disorders with transcranial Direct Current Stimulation (tDCS) have been mostly directed toward examining post-stroke aphasia. Only a few tDCS studies have focused on apraxia of speech or childhood apraxia of speech (CAS), and no study has investigated individuals with CAS and Trisomy 21 (T21, Down syndrome). This N-of-1 randomized trial examined the effects of tDCS combined with a motor learning task in developmental apraxia of speech co-existing with T21 (ReBEC RBR-5435x9). The accuracy of speech sound production of nonsense words (NSWs) during Rapid Syllable Transition Training (ReST) over 10 sessions of anodal tDCS (1.5 mA, 25 cm) over Broca's area with the cathode over the contralateral region was compared to 10 sessions of sham-tDCS and four control sessions in a 20-year-old male individual with T21 presenting moderate-severe childhood apraxia of speech (CAS). The accuracy for NSW production progressively improved (gain of 40%) under tDCS (sham-tDCS and control sessions showed < 20% gain). A decrease in speech severity from moderate-severe to mild-moderate indicated transfer effects in speech production. Speech accuracy under tDCS was correlated with Wernicke's area activation (P3 current source density), which in turn was correlated with the activation of the left supramarginal gyrus and the Sylvian parietal-temporal junction. Repetitive bihemispheric tDCS paired with ReST may have facilitated speech sound acquisition in a young adult with T21 and CAS, possibly through activating brain regions required for phonological working memory.

Altered intra- and inter-network functional activity among migraine, chronic migraine, and trigeminal neuralgia

OBJECTIVE

This study aimed to investigate the specific manifestations and differences in brain network activity and functional connectivity between brain networks in patients with trigeminal neuralgia and migraine, aiming to reveal the neural basis of these two diseases.

BACKGROUND

Head and facial pain, including trigeminal neuralgia and migraine, is prevalent globally. However, the underlying neural mechanisms of these conditions remain unclear. Resting-state functional connectivity studies based on independent component analysis (ICA) may offer new insights into these diseases.

METHODS

The study involved 23 chronic migraine, 37 episodic migraine, 21 trigeminal neuralgia patients, and 33 age- and gender-matched controls. Resting-state functional magnetic resonance imaging was performed, and five sets of brain network components were extracted through ICA. Neuronal activity indicators were calculated for each participant's independent components, including amplitudes of low-frequency fluctuation (ALFF) and regional homogeneity (ReHo). Functional connectivity was also assessed and compared among the four groups.

RESULTS

Trigeminal neuralgia patients showed reduced ALFF in the dorsal attention network versus episodic migraine patients and controls. Both trigeminal neuralgia and chronic migraine patients had decreased ReHo in this network. Migraine patients had weaker connectivity between the default mode and visual networks than controls. Trigeminal neuralgia patients also showed higher connectivity between the somatosensory motor and dorsal attention networks. Compared to episodic migraine, trigeminal neuralgia, and chronic migraine patients had increased connectivity between the visual and dorsal attention networks.

CONCLUSION

The study provides evidence that long-term chronic head and facial pain may contribute to abnormalities in the activation and connectivity of the dorsal attention network. Compared to migraine patients, trigeminal neuralgia patients exhibit abnormal brain network connectivity, particularly within the somatomotor network, which may explain the presence of significant "trigger points." These findings offer new perspectives for understanding the characteristics of different head and facial pain subtypes.

Functional connectivity of the visual cortex in chronic migraine before and after medication withdrawal therapy

Acute withdrawal of headache medication in chronic migraine patients with medication overuse may lead to a dramatic reduction in headache frequency and severity. However, the brain networks underlying chronic migraine and a favorable response to acute withdrawal are still poorly understood. The goal of the present study was to characterize the pattern of intrinsic magnetic resonance imaging (MRI) functional connectivity (FC) specific to chronic migraine and to identify changes in FC that characterize subjects with CM reverting to less frequent headaches. Subjects with chronic migraine (N = 99) underwent a resting-state functional MRI scan before and after three months of medication withdrawal therapy. In addition, we included four control groups who were scanned once: healthy participants (N = 27), patients with episodic migraine (N = 25), patients with chronic back pain (N = 22), and patients with clinical depression (N = 17). Using dual regression analysis, we compared whole-brain voxel-level functional connectivity with ten well-known resting-state networks between chronic migraine and control groups, and between responders to treatment (≥50 % reduction in monthly headache days) and non-responders (<50 % reduction), before and after treatment. Subjects with chronic migraine showed differences in FC with a number of RS-networks, most of which involved the visual cortex, compared with healthy controls. A comparison with patients with episodic migraine, chronic pain and depression showed differences in the same direction, suggesting that altered patterns of functional connectivity in chronic migraine patients could to some extent be explained by shared symptomatology with other pain, depression, or migraine conditions. A comparison between responders and non-responders indicated that effective withdrawal reduced FC with the visual cortex for responders. Interestingly, responders already differed in functional connectivity of the visual cortex at baseline compared with non-responders. Altogether, we show that chronic migraine and successful medication withdrawal therapy are linked to changes in the functional connectivity of the visual cortex. These neuroimaging findings provide new insights into the pathways underlying migraine chronification and its reversibility.

Remotely supervised at-home tDCS for veterans with persistent post-traumatic headache: a double-blind, sham-controlled randomized pilot clinical trial

Background

Currently, there are no FDA approved therapies for persistent post-traumatic headache (PPTH) secondary to traumatic brain injury (TBI). As such neither headache nor TBI specialists have an effective means to manage PPTH. Thus, the objective of the present pilot trial was to evaluate the feasibility and preliminary efficacy of a four-week at-home remotely supervised transcranial direct current stimulation (RS-tDCS) intervention for veterans with PPTH.

Methods

Twenty-five (m = 46.6 ± 8.7 years) veterans with PPTH were randomized into two groups and received either active (n = 12) or sham (n = 13) RS-tDCS, with anodal stimulation over left dlPFC and cathodal over occipital pole. Following a four-week baseline, participants completed 20-sessions of active or sham RS-tDCS with real-time video monitoring over a period of four-weeks. Participants were assessed again at the end of the intervention and at four-weeks post-intervention. Primary outcomes were overall adherence rate (feasibility) and change in moderate-to-severe headache days per month (efficacy). Secondary outcomes were changes in total number of headache days, and PPTH-related functional outcomes.

Results

Adherence rate was high with 88% of participants (active = 10/12; sham = 12/13) fully completing tDCS interventions. Importantly, there was no significant difference in adherence between active and sham groups (p = 0.59). Moderate-to-severe headache days were significantly reduced within the active RS-tDCS group (p = 0.004), compared to sham during treatment (-2.5 ± 3.5 vs. 2.3 ± 3.4), and 4-week follow-up (-3.9 ± 6.4 vs. 1.2 ± 6.5). Total number of headache days was significantly reduced within the active RS-tDCS (p = 0.03), compared to sham during-treatment (-4.0 ± 5.2 vs. 1.5 ± 3.8), and 4-week follow-up (-2.1 ± 7.2 vs. -0.2 ± 4.4).

Conclusion

The current results indicate our RS-tDCS paradigm provides a safe and effective means for reducing the severity and number of headache days in veterans with PPTH. High treatment adherence rate and the remote nature of our paradigm indicate RS-tDCS may be a feasible means to reduce PPTH, especially for veterans with limited access to medical facilities.Clinical Trial Registration: ClinicalTrials.gov, identifier [NCT04012853].

Altered Resting-State Brain Activity and Functional Connectivity in Post-Stroke Apathy: An fMRI Study

Apathy is a common neuropsychiatric disease after stroke and is linked to a lower quality of life while undergoing rehabilitation. However, it is still unknown what are the underlying neural mechanisms of apathy. This research aimed to explore differences in the cerebral activity and functional connectivity (FC) of subjects with post-stroke apathy and those without it. A total of 59 individuals with acute ischemic stroke and 29 healthy subjects with similar age, sex, and education were recruited. The Apathy Evaluation Scale (AES) was used to evaluate apathy at 3 months after stroke. Patients were split into two groups-PSA (n = 21) and nPSA (n = 38)-based on their diagnosis. The fractional amplitude of low-frequency fluctuation (fALFF) was used to measure cerebral activity, as well as region-of-interest to region-of-interest analysis to examine functional connectivity among apathy-related regions. Pearson correlation analysis between fALFF values and apathy severity was performed in this research. The values of fALFF in the left middle temporal regions, right anterior and middle cingulate regions, middle frontal region, and cuneus region differed significantly among groups. Pearson correlation analysis showed that the fALFF values in the left middle temporal region (p < 0.001, r = 0.66) and right cuneus (p < 0.001, r = 0.48) were positively correlated with AES scores in stroke patients, while fALFF values in the right anterior cingulate (p < 0.001, r = -0.61), right middle frontal gyrus (p < 0.001, r = -0.49), and middle cingulate gyrus (p = 0.04, r = -0.27) were negatively correlated with AES scores in stroke patients. These regions formed an apathy-related subnetwork, and functional connectivity analysis unveiled that altered connectivity was linked to PSA (p < 0.05). This research found that abnormalities in brain activity and FC in the left middle temporal region, right middle frontal region, right cuneate region, and right anterior and middle cingulate regions in stroke patients were associated with PSA, revealing a possible neural mechanism and providing new clues for the diagnosis and treatment of PSA.

Efficacy of tDCS in chronic migraine: A multiprotocol randomized controlled trial

OBJECTIVE

Given the prevalence and complicated pathophysiology of migraine, unknown or varied mechanisms of action of available monotherapies or add-on therapies, and their broad range of adverse effects, it is imperative to manage migraine symptoms using a non-invasive, multifunctional, and alternate monotherapy with no negative impacts.

METHODS

We used a single-blind, randomized, sham-controlled design with baseline, post-test, and 24-weeks follow-up measurements to assess the efficacy of transcranial Direct Current Stimulation (tDCS) in chronic migraine. A total of 150 participants were randomly assigned to the five groups (i.e., allocation ratio of 1:1:1:1:1). Each group received tDCS-intervention for 11 consecutive-weeks (25 sessions; each session = two consecutive montages; each montage = a 20 min duration, 2000 μA intensity).

RESULTS

The multivariate analysis of variance showed significant (p <.05) reductions in chronic migraine symptoms in the four intervention groups. Compared with the sham (η² < 0.18) and other protocols (two = η² > 0.42; three = η² > 0.40; four = η² > 0.51), protocol one [l. anode at the right ventrolateral prefrontal cortices, cathode at the left dorsomedial and superior frontal gyrus-first montage; anode at the right primary motor area, cathode at the medial crosstalk of hemispheres-second montage] showed a larger effect size (η² > 0.59) in the present trial.

CONCLUSIONS

With the applied protocols of the present trial, tDCS can be used as an effective intervention for the prophylactic and therapeutic treatment of chronic migraine. However, while the second protocol was the least effective, the first was the most effective at reducing migraine symptoms.

SIGNIFICANCE

To our knowledge, the present trial is the first study to cover the gaps of the earlier ones, including the parameters like the site of stimulation, electrode range distribution and field intensity, number of sessions, session design, and sample size.

Altered brain function in patients with vestibular migraine: a study on resting state functional connectivity

PURPOSE

To characterize the altered brain function in patients with vestibular migraine (VM) using resting-state functional magnetic resonance imaging (fMRI).

METHODS

In this prospective study, fMRI images as well as clinical characteristics and behavioral scales were collected from 40 VM patients and 40 healthy controls (HC). All patients received neurological, neuro-otological, and conventional MRI examinations to exclude peripheral vestibular lesions, focal lesions, and other neurological diseases. Seed-based (bilateral parietal operculum cortex 2, OP2) functional connectivity (FC) and independent component analysis (ICA)-based functional network connectivity (FNC) were performed to investigate the brain functional changes in patients with VM. Additionally, the correlations between the altered FC/FNC and behavioral results were analyzed.

RESULTS

Compared with HC, patients with VM showed increased FC between the left OP2 and right precuneus and exhibited decreased FC between the left OP2 and left anterior cingulate cortex. We also observed increased FC between the right OP2 and regions of the right middle frontal gyrus and bilateral precuneus, as well as decreased FC between the bilateral OP2. Furthermore, patients with VM showed decreased FNC between visual network (VN) and networks of auditory and default mode, and exhibited increased FNC between VN and executive control network. A correlation analysis found that FC between the left OP2 and right precuneus was positively correlated with scores of dizziness handicap inventory (DHI) in patients with VM.

CONCLUSION

The present study demonstrated altered brain function in patients with VM.

Aberrant dynamic functional network connectivity in vestibular migraine patients without peripheral vestibular lesion

PURPOSE

This study aimed to investigate changes in dynamic functional network connectivity (FNC) in patients with vestibular migraine (VM) and explore their relationship with clinical manifestations.

METHODS

Resting-state functional magnetic resonance imaging (rs-fMRI) data were scanned from 35 VM patients without peripheral vestibular lesion and 40 age-, sex- and education-matched healthy controls (HC). Independent component analysis (ICA), sliding window (SW) and k-means clustering analysis were performed to explore the difference in FNC and temporal characteristics between two groups. Additionally, Pearson's partial correlation analysis was adopted to investigate the relationship between clinical manifestations and rs-fMRI results in patients with VM.

RESULTS

Compared with HC, patients with VM showed increased FNC in pairs of extrastriate visual network (eVN)-ventral attention network (VAN), eVN-default mode network (DMN) and eVN-left frontoparietal network (lFPN), and exhibited decreased FNC in pairs of VAN-auditory network (AuN). The altered FNC was correlated with clinical manifestations of patients with VM. Additionally, we found increased mean dwell time and fractional windows in state 2 in VM patients compared with HC. Mean dwell time was positively correlated with headache impact test-6 (HIT-6) scores, fractional windows was positively associated with dizziness handicap inventory (DHI) scores.

CONCLUSION

Our results indicated that patients with VM showed altered FNC primarily between sensory networks and networks related to cognitive, emotional and attention implementation, with more time spent in a state characterized by positive FNC between sensor cortex system and dorsal attention network (DAN). These findings could help reinforce the understanding on the neural mechanisms of VM.

PAQR8 and PAQR9 expression is altered in the ventral tegmental area of aged rats infected with varicella zoster virus

Infection with varicella zoster virus (VZV) results in chicken pox and reactivation of VZV results in herpes zoster (HZ) or what is often referred to as shingles. Patients with HZ experience decreased motivation and increased emotional distress consistent with functions of the ventral tegmental area (VTA) of the brain. In addition, activity within the ventral tegmental area is altered in patients with HZ. HZ primarily affects individuals that are older and the VTA changes with age. To begin to determine if the VTA has a role in HZ symptoms, a screen of 10,000 genes within the VTA in young and old male rats was completed after injecting the whisker pad with VZV. The two genes that had maximal change were membrane progesterone receptors PAQR8 (mPRβ) and PAQR9 (mPRε). Neurons and non-neuronal cells expressed both PAQR8 and PAQR9. PAQR8 and PAQR9 protein expression was significantly reduced after VZV injection of young males. In old rats PAQR9 protein expression was significantly increased after VZV injection and PAQR9 protein expression was reduced in aged male rats versus young rats. Consistent with previous results, pain significantly increased after VZV injection of the whisker pad and aged animals showed significantly more pain than young animals. Our data suggests that PAQR8 and PAQR9 expression is altered by VZV injection and that these changes are affected by age.

What imaging has revealed about migraine and chronic migraine

Although migraine pathophysiology is not yet entirely understood, it is now established that migraine should be viewed as a complex neurological disease, which involves the interplay of different brain networks and the release of signaling molecules, instead of a pure vascular disorder. The field of migraine research has also progressed significantly due to the advancement of brain imaging techniques. Numerous studies have investigated the relation between migraine pathophysiology and cerebral hemodynamic changes, showing that vascular changes are neither necessary nor sufficient to cause the migraine pain. Abnormal function and structure of key cortical, subcortical, and brainstem regions involved in multisensory, including pain, processing have been shown to occur in migraine patients during both an acute attack and the interictal phase. Whether brain imaging alterations represent a predisposing trait or are the consequence of the recurrence of headache attacks is still a matter of debate. It is highly likely that brain functional and structural alterations observed in migraine patients derive from the interaction between predisposing brain traits and experience-dependent responses. Neuroimaging studies have also enriched our knowledge of the mechanisms responsible for migraine chronification and have shed light on the mechanisms of actions of acute and preventive migraine treatments.

Pathophysiology of Chronic Migraine: Insights from Recent Neuroimaging Research

PURPOSE OF REVIEW

Chronic migraine (CM) is a highly disabling primary headache disorder with a substantial impact on patients' quality of life. Episodic migraine (EM) and CM are dynamic states; CM usually evolves from EM alongside increased headache frequency, comorbidities, and medication overuse, supporting the notion that migraine is a spectrum disorder. This narrative review aims to summarize neuroimaging studies to better understand the pathophysiology of CM.

RECENT FINDINGS

Positron emission tomography studies have revealed abnormal energy metabolism and metabolic changes in the dorsal rostral pons in individuals with CM, suggesting that this structure has a key role in the pathophysiology of migraine generation and chronification. Magnetic resonance spectroscopy studies have suggested that thalamocortical pathway dysfunction may contribute to migraine chronification, while functional magnetic resonance imaging studies have highlighted that hypothalamic activity may be involved. Recent evidence highlights functional and structural alterations in cortical and subcortical pain-related brain regions in patients with CM. Whether these functional and structural abnormalities of the brain cause migraine chronification or are a consequence of repeated attacks is still debated. In the future, imaging patterns that predict the transformation from EM to CM should be identified.

Current Perspectives on the Impact of Chronic Migraine on Sleep Quality: A Literature Review

OBJECTIVE

Recent studies have shown that sleep problems occur in migraineurs and poor sleep causes chronification, but the mechanisms by which chronic migraine affects sleep quality are still unknown. This review aims to analyze commonly reported sleep disturbances in chronic migraine (CM) and determine the effect of CM on sleep quality.

MATERIALS AND METHODS

We conducted a comprehensive review of all published articles on CM and sleep quality from inception to March 2022 in the literature. Clinical trials, observational studies, and case series (≥20 cases) were included. Two reviewers and a supervisor reviewed the titles and abstracts of all search results with predefined inclusion and exclusion criteria. PubMed search for randomized controlled trials and open studies on CM and sleep quality reported in English between 1983 and 2022 was conducted using the keywords including chronic migraine, sleep, insomnia, sleep quality, polysomnography, and Pittsburgh Sleep Quality Index.

RESULTS

A total of 535 potentially relevant articles were found. A total of 455 articles and reviews, meta-analyses published in any language other than English, with other exclusion criteria, were excluded from the review. In the remaining articles, 36 clinical studies, reviewing sleep quality and its association with migraine, were identified and reviewed. Evidence from this review shows that poor sleep and migraine chronicity are intertwined with other accompanying comorbidities and dysregulation of circadian rhythm that innovative treatments promise to bring relief to both poor sleep as well as migraine.

CONCLUSION

Sleep disorders are common in CM and the association between migraine chronification and sleep quality is bidirectional. Comorbid conditions with accompanying frequent attacks in migraine may impair sleep quality. While the maladaptive pain process worsens sleep, poor sleep quality also negatively affects migraine pain. Sleep disturbance, which is affected by worsening migraine attacks, causes deterioration in the quality of life, loss of workforce, and economic burden.

Suicide Attempts in US Veterans with Chronic Headache Disorders: A 10-Year Retrospective Cohort Study

Objectives

A large-scale retrospective analysis of veterans with chronic pain was conducted to examine (1) the annual incidence of suicide attempts (SA) in veterans with chronic headache and other chronic pain conditions, and (2) the risk of SA in men and women with chronic headache and chronic headache concurrent with traumatic brain injury (TBI) as compared to non-headache chronic pain.

Methods

This retrospective study (N=3,247,621) analyzed National Veterans Affair Health Administrative data of patients diagnosed with chronic head, neck, back and other chronic pain from 2000 to 2010. Multivariable Poisson regression was used to explore the relative risks of SA in veterans with chronic headache and chronic headache concurrent with TBI as stratified by sex.

Results

Veterans with chronic headaches had the highest annual incidence of SA (329 to 491 per 100,000) each year among all identified types of chronic pain conditions. Compared to other non-headache chronic pain, chronic headache is associated with increased risk of SA [men RR (1.48), CI (1.37,1.59); women RR (1.64), CI (1.28,2.09)], after adjusting for demographic factors, TBI, and psychiatric comorbidities. The risk increased further when chronic headache is comorbid with TBI [men RR (2.82), CI (2.60, 3.05); women RR (2.16, CI (1.67-2.78)].

Conclusion

Veterans with chronic headache have a higher risk of SA than those with other chronic pain and women with chronic headache are at a higher risk than men with chronic headache. Chronic headache concurrent with TBI further heightened this risk, especially in men. Our data underscore the importance of identifying specific types of chronic pain in veterans with comorbid TBI and sex disparity associated with SA when targeting suicide prevention measures.

A volumetric magnetic resonance imaging study in migraine

Background

Although migraine phenotype has been widely described, the explanation of migraine pathophysiology still has a gap that might be partly bridged by neuroimaging investigations. The aim of the study is to assess volumetric brain changes in migraineurs compared with controls, and in episodic migraine in comparison to chronic type. Structural brain changes in migraineurs (with and without aura) were assessed by an automated segmentation method (Free Surfer). T1-weighted MRIs of 25 migraineurs (14 diagnosed as episodic type and 11 diagnosed as chronic migraine) and 25 headache-free controls were evaluated and processed.

Results

Migraine patients had significant reduction of the volume of total brain, grey matter, brain stem, cerebellum, basal ganglia, thalamus, hippocampus and amygdala in comparison to control subjects. Patients with chronic migraine had significant reduction in volume of total brain, grey matter, cerebellum and frontal lobe thickness in comparison to those with episodic migraine.

Conclusion

Migraineurs showed volumetric brain changes mainly in areas related to central processing of pain and in areas specific for migraine (such as brain stem) when compared to healthy controls. Chronic migraineurs showed significant reduction in grey matter, in areas involved in processing of pain, cognition and multisensory integration versus patients with episodic migraine, which adds insight into the pathophysiology of migraine as a progressive disorder that may have long-term impacts on the brain as regards structure and function.

Aberrant modulations of static functional connectivity and dynamic functional network connectivity in chronic migraine

Background

Chronic migraine (CM) is a common and disabling neurological disorder that affects 1-2% of the global population. The aim of the present study was to identify the functional characteristics of the CM brain using static functional connectivity (s-FC), static functional network connectivity (s-FNC), and dynamic functional network connectivity (d-FNC) analyses.

Methods

In the present study, 17 CM patients and 20 sex- and age-matched healthy controls (HCs) underwent resting-state functional magnetic resonance imaging. We utilized independent component (IC) analysis to identify 13 ICs. These 13 ICs were then classified into the following 6 resting-state networks (RSNs): the default mode network (DMN), executive control network (ECN), dorsal attention network, auditory network (AN), visual network (VN), and cerebellum network. Subsequently, s-FC, s-FNC, and d-FNC analyses of 13 ICs were employed for between-group comparisons. Three temporal metrics (fraction of time spent, mean dwell time, and number of transitions), which were derived from the state-transition vector, were calculated for group comparisons. In addition, correlation analyses were performed between these dynamic metrics and clinical characteristics [mean visual analog scale (VAS) scores, days with headache per month, days with migraine pain feature per month, and disease duration].

Results

In the comparison of s-FC of 13 ICs within RSNs between the CM and HC groups, increased connectivity was observed in the left angular gyrus (Angular_L) of the ECN (IC 2) and the right superior parietal gyrus (Parietal_Sup_R) of the AN (IC 5), and reduced connectivity was found in the left superior frontal gyrus (Frontal_Sup_2_L) of the AN (IC 5) and DMN (IC 19), the right calcarine sulcus (Calcarine_R) of the VN (IC 7), and the left precuneus (Precuneus_L) of the DMN (IC 17) in CM patients. In the comparison of the d-FNC of 13 IC pairs within RSNs between the two groups, the CM group exhibited significantly decreased connections between the DMN (IC 11) and AN (IC 5), and increased connections between the ECN (IC 2, IC 4) and DMN (IC 19), ECN (IC 4) and AN (IC 5), and ECN (IC 4) and VN (IC 13) in state 1. However, no significant differences in s-FNC were observed between the two groups during the s-FNC analysis. Between-group comparisons of three dynamic metrics between the CM and HC groups showed a longer fraction of time spent and mean dwell time in state 2 for CM patients. Furthermore, from the correlation analyses between these metrics and clinical characteristics, we observed a significant positive correlation between the number of transitions and mean VAS scores.

Conclusions

Our findings suggest that functional features of the CM brain may fluctuate over time instead of remaining static, and provide further evidence that migraine chronification may be related to abnormal pattern connectivity between sensory and cognitive brain networks.

Network Analysis of Induced Neural Plasticity Post-Acceptance and Commitment Therapy for Chronic Pain

Chronic musculoskeletal pain is a costly and prevalent condition that affects the lives of over 50 million individuals in the United States. Chronic pain leads to functional brain changes in those suffering from the condition. Not only does the primary pain network transform as the condition changes from acute to persistent pain, a state of hyper-connectivity also exists between the default mode, frontoparietal, and salience networks. Graph theory analysis has recently been used to investigate treatment-driven brain network changes. For example, current research suggests that Acceptance and Commitment Therapy (ACT) may reduce the chronic pain associated hyper-connectivity between the default mode, frontoparietal, and salience networks, as well as within the salience network. This study extended previous work by examining the associations between the three networks above and a meta-analytically derived pain network. Results indicate decreased connectivity within the pain network (including left putamen, right insula, left insula, and right thalamus) in addition to triple network connectivity changes after the four-week Acceptance and Commitment Therapy intervention.

The Instant Effects of Continuous Transcutaneous Auricular Vagus Nerve Stimulation at Acupoints on the Functional Connectivity of Amygdala in Migraine without Aura: A Preliminary Study

Background

A growing body of evidence suggests that both auricular acupuncture and transcutaneous auricular vagus nerve stimulation (taVNS) can induce antinociception and relieve symptoms of migraine. However, their instant effects and central treatment mechanism remain unclear. Many studies proved that the amygdalae play a vital role not only in emotion modulation but also in pain processing. In this study, we investigated the modulation effects of continuous taVNS at acupoints on the FC of the bilateral amygdalae in MwoA.

Methods

Thirty episodic migraineurs were recruited for the single-blind, crossover functional magnetic resonance imaging (fMRI) study. Each participant attended two kinds of eight-minute stimulations, taVNS and sham-taVNS (staVNS), separated by seven days in random order. Finally, 27 of them were included in the analysis of seed-to-voxel FC with the left/right amygdala as seeds.

Results

Compared with staVNS, the FC decreased during taVNS between the left amygdala and left middle frontal gyrus (MFG), left dorsolateral superior frontal gyrus, right supplementary motor area (SMA), bilateral paracentral lobules, bilateral postcingulum gyrus, and right frontal superior medial gyrus, so did the FC of the right amygdala and left MFG. A significant positive correlation was observed between the FC of the left amygdala and right SMA and the frequency/total time of migraine attacks during the preceding four weeks.

Conclusion

Continuous taVNS at acupoints can modulate the FC between the bilateral amygdalae and pain-related brain regions in MwoA, involving the limbic system, default mode network, and pain matrix, with obvious differences between the left amygdala and the right amygdala. The taVNS may produce treatment effects by modulating the abnormal FC of the amygdala and pain networks, possibly having the same central mechanism as auricular acupuncture.

How does the brain change in chronic migraine? Developing disease biomarkers

BACKGROUND

Validated chronic migraine biomarkers could improve diagnostic, prognostic, and predictive abilities for clinicians and researchers, as well as increase knowledge on migraine pathophysiology.

OBJECTIVE

The objective of this narrative review is to summarise and interpret the published literature regarding the current state of development of chronic migraine biomarkers.

FINDINGS

Data from functional and structural imaging, neurophysiological, and biochemical studies have been utilised towards the development of chronic migraine biomarkers. These biomarkers could contribute to chronic migraine classification/diagnosis, prognosticating patient outcomes, predicting response to treatment, and measuring treatment responses early after initiation. Results show promise for using measures of brain structure and function, evoked potentials, and sensory neuropeptide concentrations for the development of chronic migraine biomarkers, yet further optimisation and validation are still required.

CONCLUSIONS

Imaging, neurophysiological, and biochemical changes that occur with the progression from episodic to chronic migraine could be utilised for developing chronic migraine biomarkers that might assist with diagnosis, prognosticating individual patient outcomes, and predicting responses to migraine therapies. Ultimately, validated biomarkers could move us closer to being able to practice precision medicine in the field and thus improve patient care.

Brain Functional Alternations of the Pain-related Emotional and Cognitive Regions in Patients with Chronic Shoulder Pain

OBJECTIVE

Chronic shoulder pain (CSP) is a common health problem associated with shoulder dysfunction and persistent pain for many different reasons. However, the studies of pain-related functional brain regions in CSP have been poorly investigated. The main purpose of our study was to observe whether there are abnormal functional changes in brain regions in patients with CSP by using functional magnetic resonance imaging (fMRI).

PATIENTS AND METHODS

We compared the differences of brain regions between 37 patients with CSP and 24 healthy controls (HC) using regional homogeneity (ReHo) method. The patients with chronic shoulder pain and healthy controls were matched for age and gender. Brain regions which had abnormal ReHo values were defined as seed region of interests. The approach of seed-based functional connectivity (FC) was further performed to analyze the connectivity between the seeds and whole brain regions. The relationship between abnormal regions and current clinical pain was also evaluated.

RESULTS

Compared to healthy controls, the patients with CSP showed increased ReHo values in the left middle temporal gyrus and decreased ReHo values in right orbitofrontal cortex (OFC). The seed-based analyses demonstrated decreased connectivity between the right OFC and right rectus, superior frontal gyrus in patients with chronic shoulder pain. However, a correlation between ReHo values and clinical characteristics in CSP patients was not found.

CONCLUSION

The observed results indicate that there are abnormal ReHo values in brain regions of patients with CSP, especially in the OFC and middle temporal gyrus. Our findings demonstrate that the experience of CSP patients may be mainly associated with cognitive-affective pain processing, rather than nociception.

Linking Pain Sensation to the Autonomic Nervous System: The Role of the Anterior Cingulate and Periaqueductal Gray Resting-State Networks

There are bi-directional interactions between the autonomic nervous system (ANS) and pain. This is likely underpinned by a substantial overlap between brain areas of the central autonomic network and areas involved in pain processing and modulation. To date, however, relatively little is known about the neuronal substrates of the ANS-pain association. Here, we acquired resting state fMRI scans in 21 healthy subjects at rest and during tonic noxious cold stimulation. As indicators of autonomic function, we examined how heart rate variability (HRV) frequency measures were influenced by tonic noxious stimulation and how these variables related to participants’ pain perception and to brain functional connectivity in regions known to play a role in both ANS regulation and pain perception, namely the right dorsal anterior cingulate cortex (dACC) and periaqueductal gray (PAG). Our findings support a role of the cardiac ANS in brain connectivity during pain, linking functional connections of the dACC and PAG with measurements of low frequency (LF)-HRV. In particular, we identified a three-way relationship between the ANS, cortical brain networks known to underpin pain processing, and participants’ subjectively reported pain experiences. LF-HRV both at rest and during pain correlated with functional connectivity between the seed regions and other cortical areas including the right dorsolateral prefrontal cortex (dlPFC), left anterior insula (AI), and the precuneus. Our findings link cardiovascular autonomic parameters to brain activity changes involved in the elaboration of nociceptive information, thus beginning to elucidate underlying brain mechanisms associated with the reciprocal relationship between autonomic and pain-related systems.

Early Age of Migraine Onset is Independently Related to Cognitive Decline and Symptoms of Depression Affect Quality of Life

Background

People with migraine experience cognitive decline more often than healthy controls, resulting in a significant functional impact. Early identifying influencing factors that contribute to cognitive decline in migraineurs is crucial for timely intervention. Although migraine may onset early in childhood and early onset migraine is related to significant disability, there is no research investigating the association between the age of migraine onset and migraineurs’ cognitive decline. Therefore we aim to explore possible factors that correlate to the cognitive function of migraineurs, especially focus on age of migraine onset.

Methods

531 patients with migraine were included. Data on demographics and headache-related characteristics were collected and evaluated using face-to-face interviews and questionnaires. We used the Montreal Cognitive Assessment scale to assess cognitive function. In addition, we analyzed independent correlations between cognitive decline and the age of migraine onset in patients with migraine. And all patients completed the Headache Impact Test-6 to evaluate their quality of life.

Results

Migraineurs with cognitive decline showed significant differences from those without in age (OR=1.26, P<0.0001), years of education (OR=0.89, P=0.0182), the intensity of headache (OR=1.03, P=0.0217), age of onset (OR=0.92, P<0.0001) and anxiety scores (OR=1.09, P=0.0235). Furthermore, there was no interaction in the age of onset between subgroups. Multivariate linear regression analyses of HIT-6 scores showed that the intensity of headache (β=0.18, P<0.0001) and depression scores (β=0.26, P=0.0009) had independent effects on decreased quality of life.

Conclusion

Our findings suggest that younger age of migraine onset is independently related to migraineurs’ cognitive decline, and migraine accompanying anxiety symptoms significantly related to decreased quality of life in migraineurs.

Brain Structural and Functional Imaging Findings in Medication-Overuse Headache

This chapter overviews research neuroimaging findings of patients with medication-overuse headache (MOH). Results indicate; (i) correlations between neuropathology and medication-overuse; (ii) changes in brain morphology and cortical function; and (iii) brain recovery subsequent to withdrawal of medication that was overused. Results of this narrative review indicate exacerbated brain structural and functional changes in regions of the pain-matrix and in regions of the mesocortical-limbic circuit in patients with MOH compared to patients with migraine or compared to healthy controls. Modification of brain morphology as well as an association between brain recovery and medication withdrawal suggest that the MOH disease process involves state (brain modification) and trait-like (brain adaptation and recovery) neuromechanisms.

The Chronic Migraine Brain: What Have We Learned From Neuroimaging?

Chronic migraine is a highly disabling disease with a great impact on socioeconomic functioning and quality of life of migraine patients. Chronic migraine usually evolves from episodic migraine that gradually increases in attack frequency, supporting the view of migraine as a spectrum disorder. Pathophysiological mechanisms responsible for migraine chronification are not fully understood. Likewise episodic migraine, chronic migraine patients show widespread functional and structural alterations of cortical and subcortical pain-related brain areas. However, chronic migraine patients experience a more pronounced dysfunction of the pain inhibitory network and an increased sensitization of the central pain pathways, which might explain the higher susceptibility to migraine attacks. Imaging studies have highlighted that brain regions with a key role in migraine attack generation, like the pons and hypothalamus, might also be involved in migraine chronification. Whether brain alterations are biomarkers that predispose migraine patients to chronification or reflect adaptive or maladaptive responses to the increasing headache frequency is still a matter of debate. The central mechanisms of action of chronic migraine preventive treatments and imaging biomarkers that could predict patients' treatment response have also been explored. In this new era of migraine treatments, a better understanding of chronic migraine pathophysiology will pave the way for the development of new improved treatments specifically designed for chronic migraine patients.

Regional volume changes of the brain in migraine chronification

The pathophysiology of migraine is complex. Neuroimaging studies reveal functional and structural changes in the brains of migraine patients. We sought to explore regional volume differences in intracranial structures in patients with episodic and chronic migraine. Sixteen episodic migraine patients, 16 chronic migraine patients, and 24 normal controls were recruited and underwent 3.0 T MRI scanning. The volumes of 142 brain regions were calculated by an automatic volumetric algorithm and compared with clinical variables. Results demonstrated that the volumes of specific regions in the frontal and occipital lobes, and the right putamen, were increased and the volume of the fourth ventricle was decreased in the episodic migraine patients compared with controls. The volumes of the left basal forebrain, optic chiasm, and, the fourth ventricle were decreased in the chronic migraine patients, while the occipital cortex and the right putamen were larger. Compared to episodic migraine patiants, chronic migraine patients displayed larger left thalamus and smaller frontal regions. Correlation analysis showed that headache frequency was negatively correlated with the volume of the right frontal pole, right lateral orbital gyrus, and medial frontal lobes and positively correlated with the volume of the left thalamus. The sleep disturbance score was negatively correlated with the volume of the left basal forebrain. This suggests that migraine patients have structural changes in regions associated with pain processing and modulation, affective and cognitive processing, and visual perception. The remodeling of selective intracranial structures may be involved in migraine attacks. This study was approved by the Ethics Committee of Chinese PLA General Hospital (approval No. S2018-027-02) on May 31, 2018.

Biological and behavioral markers of pain following nerve injury in humans

The evolution of peripheral and central changes following a peripheral nerve injury imply the onset of afferent signals that affect the brain. Changes to inflammatory processes may contribute to peripheral and central alterations such as altered psychological state and are not well characterized in humans. We focused on four elements that change peripheral and central nervous systems following ankle injury in 24 adolescent patients and 12 age-sex matched controls. Findings include (a) Changes in tibial, fibular, and sciatic nerve divisions consistent with neurodegeneration; (b) Changes within the primary motor and somatosensory areas as well as higher order brain regions implicated in pain processing; (c) Increased expression of fear of pain and pain reporting; and (d) Significant changes in cytokine profiles relating to neuroinflammatory signaling pathways. Findings address how changes resulting from peripheral nerve injury may develop into chronic neuropathic pain through changes in the peripheral and central nervous system.