Pregabalin influences insula and amygdala activation during anticipation of emotional images

Neuropathic pain in cats: Mechanisms and multimodal management

PRACTICAL RELEVANCE

Chronic pain is a significant welfare concern in cats, and neuropathic pain, which arises from aberrant processing of sensory signals within the nervous system, is a subcategory of this type of pain. To comprehend this condition and how multimodal pharmacotherapy plays a central role in alleviating discomfort, it is crucial to delve into the anatomy of nociception and pain perception. In addition, there is an intricate interplay between emotional health and chronic pain in cats, and understanding and addressing the emotional factors that contribute to pain perception, and vice versa, is essential for comprehensive care.Clinical approach:Neuropathic pain is suspected if there is abnormal sensation in the area of the distribution of pain, together with a positive response to trial treatment with drugs effective for neuropathic pain. Ideally, this clinical suspicion would be supported by confirmation of a lesion at this neurolocalisation using diagnostic modalities such as MRI and neuroelectrophysiology. Alternatively, there may be a history of known trauma at that site. A variety of therapies, including analgesic, anti-inflammatory and adjuvant drugs, and neuromodulation (eg, TENS or acupuncture), can be employed to address different facets of pain pathways.Aim:This review article, aimed at primary care/ general practitioners, focuses on the identification and management of neuropathic pain in cats. Three case vignettes are included and a structured treatment algorithm is presented to guide veterinarians in tailoring interventions.Evidence base:The review draws on current literature, where available, along with the author's extensive experience and research.

Pregabalin Alleviates Anxiety and Fear in Cats during Transportation and Veterinary Visits-A Clinical Field Study

Cats frequently suffer from anxiety related to travel and veterinary visits. One sequela is avoidance of veterinary visits and lack of adequate veterinary care. The objective of this study was to test clinical efficacy and safety of a novel formulation of a pregabalin 50 mg/mL oral solution for alleviation of anxiety and fear in cats during transport and veterinary visits. A total of 209 client-owned cats were given either a flavored pregabalin oral solution at the dosage of 5 mg/kg (n = 108) or an identical placebo (n = 101) approximately 90 min before placing them into the carrier and transporting them in a car for at least 20 min to a veterinary clinic. The treatment effect using a 5-point numerical rating scale was evaluated during transportation by the owner and during clinical examination by the veterinarian, both blinded to the treatment. In addition, to verify the owner assessment, an external expert blinded to the treatment and owner assessment evaluated the transportation video recordings using the same rating scale as the owner. Pregabalin 5 mg/kg statistically significantly decreased both travel- (p < 0.01) and veterinary-visit- (p < 0.01) related anxiety compared to the placebo. The external expert's evaluation was in agreement with the owners' assessment confirming the treatment effect during transportation (p < 0.01). Treatment was well tolerated with only a few cats showing transient slight incoordination and tiredness. The flavored oral solution formulation with a small dosing volume of 0.1 mL/kg was found by the owners to be user-friendly and was well-accepted by the cats. This study demonstrated that a single oral dosage of the novel pregabalin oral solution alleviates anxiety and fear related to transportation and veterinary visits in cats, thus providing practical aid for both owners and veterinarians to enable cat-friendly handling and improving the welfare of cats in situations they often perceive as very stressful.

Non-invasive cervical vagus nerve stimulation effects on reaction time and valence image anticipation response

BACKGROUND

Norepinephrine (NE) driven noninvasive vagus nerve stimulation (nVNS), which improves attention and reduces reaction time, augments learning. Equally important, endogenous NE mediated arousal is highly dependent on the valence (positive or negative) of the exogenous stimulus. But to date, no study has measured valence specific effects of nVNS on both functional magnetic resonance imaging (fMRI) anticipation task response and reaction time in healthy individuals. Therefore, the aim of this pilot study was to assess whether nVNS vs sham modulates valence cortical anticipation task response and reaction time in a normative sample.

METHODS

Participants received right sided transcutaneous cervical nVNS (N = 12) or sham (N = 12) stimulation during a 3T fMRI scan. Subjects first performed a continuous performance task (CPT) and then a cued anticipation task to images of positively and negatively valenced events during fMRI. Reaction times to cues and Blood oxygen level dependent (BOLD) response were examined over phase to identify effects of nVNS/sham over time.

RESULTS

nVNS reduced reaction time for all valenced image anticipation trials. With the fMRI anticipation task, we observed a valence-specific effect; nVNS increased responsivity to images with negative valence and decreased responsivity to images with positive valence, whereas sham showed an inverse valence response.

CONCLUSIONS

nVNS was linked to reduced reaction time during the anticipation task. In tandem, nVNS consistently enhanced responsivity to negatively valenced images and diminished responsivity to positively valenced images, suggesting specific nVNS driven endogenous neurotransmitter signaling may contribute.

High-dose baclofen attenuates insula activation during anticipatory anxiety in treatment-seeking alcohol dependant individuals: Preliminary findings from a pharmaco-fMRI study

The GABA _B agonist, baclofen, has been shown to reduce alcohol consumption in patients with alcohol use disorder and also those with comorbid anxiety. This study aimed to evaluate the effect of baclofen versus placebo on the BOLD response during an anticipatory anxiety fMRI task in treatment seeking alcohol patients. Participants included 28 alcohol dependant individuals who had received daily baclofen 30 mg (n = 10), 75 mg (n = 8) or placebo (n = 10) for at least 2 week on a randomized controlled trial (Morley, Leung et al. 2013, Morley, Baillie et al. 2018). Using functional magnetic resonance imaging (fMRI), we examined threat cue-elicited neural activation during a threat reactivity task 120 min following administration of BAC (30 mg or 75 mg) or placebo. Whole-brain analyses revealed no significant differences between the combined BAC doses versus PL. However, there were significant decreases in anticipatory threat cue-elicited activation observed in BAC 75 mg/day compared to PL participants in the insula. In response to threat cues, high dose (75 mg/day) baclofen administration attenuates activation in the insula and inferior frontal gyrus, relative to placebo. These preliminary findings suggests that modulating emotional regulation and attentional allocation during high threat stimuli may be mediated by GABA _B receptors and may be a potential mechanism of action for baclofen's beneficial treatment effects for alcohol use disorder.

Neuromagnetic Amygdala Response to Pain-Related Fear as a Brain Signature of Fibromyalgia

INTRODUCTION

Fibromyalgia (FM) is a chronic pain condition characterized by impaired emotional regulation. This study explored the brain response to pain-related fear as a potential brain signature of FM.

METHODS

We used a conditioned fear task and magnetoencephalography to record pain-related fear responses in patients with FM. Two blocks of 30 fear responses were collected to compute the response strength in the first block and the strength difference between the first and second blocks (fear habituation). These measurements were investigated for their clinical relevance and compared with measurements obtained from healthy controls and patients with chronic migraine (CM), a different chronic pain condition often comorbid with FM.

RESULTS

Pain-related fear clearly activated the bilateral amygdala and anterior insula in patients with FM (n = 52), patients with CM (n = 50), and the controls (n = 30); the response strength in the first block was consistent across groups. However, fear habituation in the right amygdala decreased in the FM group (vs. CM and control groups, both p ≤ 0.001, no difference between CM and control groups). At the 3-month follow-up, the patients with FM reporting < 30% improvement in pain severity (n = 15) after pregabalin treatment exhibited lower fear habituation in the left amygdala at baseline (vs. ≥ 30% improvement, n = 22, p = 0.019). Receiver operating characteristic analysis confirmed that amygdala fear habituation is a suitable predictor of diagnosis and treatment outcomes of FM (area under the curve > 0.7).

CONCLUSIONS

Amygdala activation to pain-related fear is maladaptive and linked to treatment outcomes in patients with FM. Because the aberrant amygdala response was not observed in the CM group, this response is a potential brain signature of FM.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier, NCT02747940.

Neural affective mechanisms associated with treatment responsiveness in veterans with PTSD and comorbid alcohol use disorder

Post-traumatic stress disorder (PTSD) is associated with neuro-physiological abnormalities reflecting increased anticipatory anxiety and reactivity to traumatic cues. It remains unclear whether neural mechanisms associated with PTSD treatment responsiveness, i.e. hyperactivation of the affective salience network in the brain, extend to a comorbid PTSD and substance use disorder population. Thirty-one Veterans with PTSD and co-occurring alcohol use disorder (AUD) were randomly assigned to either prolonged exposure or a non-exposure based treatment. They completed an affective anticipation task while undergoing fMRI, immediately prior and after completing treatment. After controlling for type and length of treatment, larger reduction of PTSD symptoms was associated with decreased anticipatory activation to negative trauma-related cues in the right pre-Supplementary Motor Area (pre-SMA), a region associated with emotion regulation. Smaller reduction in PTSD severity was associated with enhanced anticipatory activation to those cues within the right para-hippocampal region, an affective processing region. Our findings suggest that post-treatment reductions in anticipatory reactivity to trauma-related cues in the pre-SMA and para-hippocampal area are associated with larger PTSD symptom reduction in individuals with co-occurring PTSD and AUD. These results may offer neurofeedback training targets as an alternative to or enhancement of other PTSD treatment modalities in this population.

Pregabalin as a Pain Therapeutic: Beyond Calcium Channels

Initially developed to generate new treatments for epilepsy, gabapentin, and pregabalin (“gabapentinoids”) were engineered to mimic the action of GABA and to modulate GABA metabolism. Rather than their intended pharmacological action on GABA neurotransmission, instead, they exhibit a high affinity for the α2δ-1 and α2δ-2 subunits of voltage-activated calcium channels, wherein binding of gabapentinoids inhibits cellular calcium influx and attenuates neurotransmission. Despite a lack of activity on GABA levels, gabapentin and pregabalin are effective at suppressing seizures and subsequently approved as a new class of antiepileptic therapy for partial-onset epilepsy. Through the same hypothesized molecular mechanism and by controlling neuronal hyperexcitability, gabapentinoids demonstrate clear efficacy in pain management, which has arguably been their most extensively prescribed application to date. In this review, we focus on pregabalin as a second-generation gabapentinoid widely employed in the treatment of a variety of pain conditions. We also discuss the wider functional roles of α2δ subunits and the contributions that pregabalin might play in affecting physiological and pathophysiological processes.

Effects of Stress on Itch

PURPOSE

Psychological stress and ensuing modulation of the immune and nervous systems can have a significant impact on itch. Stress can exacerbate itch and vice versa, resulting in a vicious cycle that can greatly impair a patient's quality of life. This review summarizes the association between stress and itch, elucidates the mechanism by which these two phenomena influence one another, and explores treatment modalities that aim to reduce stress-induced itch.

METHODS

A complete search of the PubMed and Google Scholar databases was completed and literature pertinent to this review was compiled.

FINDINGS

Both acute and chronic stress can significantly affect itch in healthy individuals and in those diagnosed with itchy skin diseases as well as systemic diseases, thus resulting in a vicious cycle in which stress exacerbates itch and vice versa. The mechanisms by which stress induces or aggravates itch include both central and peripheral activation of the hypothalamic-pituitary-adrenal axis and sympathetic nervous system. Activation of these systems, in turn, affects the mast cells, keratinocytes, and nerves that secrete neuropeptides, such as substance P, nerve growth factor, acetylcholine, histamine, and itchy cytokines. A dysfunctional parasympathetic response is thought to be involved in the chronic stress/itch response. Brain structures associated with emotion, such as the limbic system and periaqueductal gray, which work on the descending facilitation of itch, play a significant role in stress-induced itch.

IMPLICATIONS

As specific brain structures are associated with stress, drug treatments targeting these areas (ie, γ-aminobutyric acid-ergic drugs, serotonin and norepinephrine reuptake inhibitors) may help to modulate itch. Stress can also be combatted using nonpharmacologic treatments such as cognitive-behavioral therapies and stress-relieving holistic approaches (eg, yoga, acupuncture).

Novel pharmacological targets in drug development for the treatment of anxiety and anxiety-related disorders

Current medication for anxiety disorders is suboptimal in terms of efficiency and tolerability, highlighting the need for improved drug treatments. In this review an overview of drugs being studied in different phases of clinical trials for their potential in the treatment of fear-, anxiety- and trauma-related disorders is presented. One strategy followed in drug development is refining and improving compounds interacting with existing anxiolytic drug targets, such as serotonergic and prototypical GABAergic benzodiazepines. A more innovative approach involves the search for compounds with novel mechanisms of anxiolytic action using the growing knowledge base concerning the relevant neurocircuitries and neurobiological mechanisms underlying pathological fear and anxiety. The target systems evaluated in clinical trials include glutamate, endocannabinoid and neuropeptide systems, as well as ion channels and targets derived from phytochemicals. Examples of promising novel candidates currently in clinical development for generalised anxiety disorder, social anxiety disorder, panic disorder, obsessive compulsive disorder or post-traumatic stress disorder include ketamine, riluzole, xenon with one common pharmacological action of modulation of glutamatergic neurotransmission, as well as the neurosteroid aloradine. Finally, compounds such as D-cycloserine, MDMA, L-DOPA and cannabinoids have shown efficacy in enhancing fear-extinction learning in humans. They are thus investigated in clinical trials as an augmentative strategy for speeding up and enhancing the long-term effectiveness of exposure-based psychotherapy, which could render chronic anxiolytic drug treatment dispensable for many patients. These efforts are indicative of a rekindled interest and renewed optimism in the anxiety drug discovery field, after decades of relative stagnation.

Computer-Based Executive Function Training for Combat Veterans With PTSD: A Pilot Clinical Trial Assessing Feasibility and Predictors of Dropout

Background: While evidence-based PTSD treatments are often efficacious, 20-50% of individuals continue to experience significant symptoms following treatment. Further, these treatments do not directly target associated neuropsychological deficits. Here, we describe the methods and feasibility for computer-based executive function training (EFT), a potential alternative or adjunctive PTSD treatment. Methods: Male combat veterans with full or partial PTSD (n = 20) and combat-exposed controls (used for normative comparison; n = 20) completed clinical, neuropsychological and functional neuroimaging assessments. Those with PTSD were assigned to EFT (n = 13) or placebo training (word games; n = 7) at home for 6 weeks, followed by repeat assessment. Baseline predictors of treatment completion were explored using logistic regressions. Individual feedback and changes in clinical symptoms, neuropsychological function, and neural activation patterns are described. Results: Dropout rates for EFT and placebo training were 38.5 and 57.1%, respectively. Baseline clinical severity and brain activation (i.e., prefrontal-insula-amygdala networks) during an emotional anticipation task were predictive of treatment completion. Decreases in clinical symptoms were observed following treatment in both groups. EFT participants improved on training tasks but not on traditional neuropsychological assessments. All training completers indicated liking EFT, and indicated they would engage in EFT (alone or as adjunctive treatment) if offered. Conclusion: Results provide an initial framework to explore the feasibility of placebo-controlled, computerized, home-based executive function training (EFT) on psychological and neuropsychological function and brain activation in combat veterans with PTSD. Clinical severity and neural reactivity to emotional stimuli may indicate which veterans will complete home-based computerized interventions. While EFT may serve as a potential alternative or adjunctive PTSD treatment, further research is warranted to address compliance and determine whether EFT may benefit functioning above and beyond placebo interventions.

Effect of valproate and pregabalin on human anxiety-like behaviour in a randomised controlled trial

Valproate is an anticonvulsant drug with strong preclinical evidence for reducing anxiety behaviour in rodents but no clear clinical evidence. To motivate clinical trials, we here investigate the use of valproate in a translational human model of anxiety behaviour. In a double-blind, randomised, placebo-controlled trial, n = 118 healthy participants played a previously validated approach/avoidance conflict computer game to measure anxiety-like behaviour, while under 400 mg valproate, under 200 mg of the established anxiolytic/anticonvulsant pregabalin, or under placebo. Saccadic peak velocity and subjective ratings were assessed to control for drug-induced sedation. Compared to placebo, valproate and pregabaline were anxiolytic in the primary outcome, and several secondary outcomes. Bayesian model comparison decisively demonstrated no differences between the two drugs. Subjective and objective sedation was significantly more pronounced under pregabalin than valproate, but did not explain anxiolytic effects. We demonstrate acute anxiolytic properties of valproate in healthy humans. Both drugs have similar anxiolytic properties at the doses used. Valproate is less sedative than pregabalin. Our results suggest clinical trials on the use of valproate in anxiolytic treatment. More generally, we propose a strategy of screening drugs in human preclinical models that can directly be compared across species, such as the approach/avoidance conflict computer game used here. This approach could thus facilitate translational anxiety research.

Addiction-related interactions of pregabalin with morphine in mice and humans: reinforcing and inhibiting effects

The gabapentinoid pregabalin is a rapid-acting anxiolytic and analgesic, possibly suitable in supervised opioid detoxification. However, clinicians have been cautious in using it because of its unknown addictive risk and rising number of mortalities after pregabalin self-medication in opioid abusers. Here, we studied interactions of pregabalin and morphine on reward functions of the dopamine system in mice and the efficacy of pregabalin on withdrawal in opioid addicts. After the treatment of mice with pregabalin and morphine, we used electrophysiology to study neuroplasticity in midbrain slices, self-administration and conditioned place preference tests to investigate the rewarding potential of pregabalin and naloxone-precipitated morphine withdrawal to evaluate opioid withdrawal symptoms. Further, we ran a pilot single-blind, randomized, controlled trial (34 heroin addicts) to evaluate the efficacy and safety of pregabalin in the treatment of opioid withdrawal syndrome. Pregabalin alone did not induce glutamate receptor neuroplasticity of dopamine neurons in the ventral tegmental area, but pre-treatment with pregabalin suppressed morphine-induced neuroplasticity, hyperlocomotion and morphine self-administration. Pregabalin administration after chronic morphine exposure failed to induce any rewarding effects. Instead, pregabalin suppressed withdrawal symptoms in both morphine-treated mice and opioid addicts and was well tolerated. Intriguingly, pregabalin administration after a low dose of morphine strongly facilitated ventral tegmental area neuroplasticity and led to increased conditioned place preference. Pregabalin appears to have the efficacy to counteract both reinforcing and withdrawal effects of opioids, but it also has a potentiating effect when given to mice with existing opioid levels.

Default mode network and frontolimbic gray matter abnormalities in patients with borderline personality disorder: A voxel-based meta-analysis

Specific frontolimbic abnormalities are hypothesized to underlie the etiology of borderline personality disorder (BPD). However, findings from neuroimaging studies were inconsistent. In the current study, we aimed to provide a complete overview of cerebral microstructural alterations in gray matter (GM) of BPD patients. A total of 11 studies were enrolled, comprising 275 BPD patients and 290 healthy controls (HCs). A meta-analysis was conduct to quantitatively estimate regional GM abnormalities in BPD patients using the seed-based d mapping (SDM). Meta-regression was also conducted. Compared with HCs, the BPD patients exhibited increased GM mainly in bilateral supplementary motor area extending to right posterior cingulated cortex (PCC) and bilateral primary motor cortex, right middle frontal gyrus (MFG), and the bilateral precuneus extending to bilateral PCC. Decreased GM was identified in bilateral middle temporal gyri, right inferior frontal gyrus extending to right insular, left hippocampus and left superior frontal gyrus extending to left medial orbitofrontal cortex. The mean age of BPD patients were found nagativly associated with GM alterations in right MFG. Our findings suggested that BPD patients have significantly GM abnormalities in the default mode network and frontolimbic circuit. Our results provided further evidences in elucidating the underline neural mechanisms of BPD.

Antidepressants and gabapentinoids in neuropathic pain: Mechanistic insights

Neuropathic pain arises as a consequence of a lesion or disease affecting the somatosensory system. It is generally chronic and challenging to treat. The recommended pharmacotherapy for neuropathic pain includes the use of some antidepressants, such as tricyclic antidepressants (TCAs) (amitriptyline…) or serotonin and noradrenaline re-uptake inhibitors (duloxetine…), and/or anticonvulsants such as the gabapentinoids gabapentin or pregabalin. Antidepressant drugs are not acute analgesics but require a chronic treatment to relieve neuropathic pain, which suggests the recruitment of secondary downstream mechanisms as well as long-term molecular and neuronal plasticity. Noradrenaline is a major actor for the action of antidepressant drugs in a neuropathic pain context. Mechanistic hypotheses have implied the recruitment of noradrenergic descending pathways as well as the peripheral recruitment of noradrenaline from sympathetic fibers sprouting into dorsal root ganglia; and importance of both α2 and β2 adrenoceptors have been reported. These monoamine re-uptake inhibitors may also indirectly act as anti-proinflammatory cytokine drugs; and their therapeutic action requires the opioid system, particularly the mu (MOP) and/or delta (DOP) opioid receptors. Gabapentinoids, which target the voltage-dependent calcium channels α2δ-1 subunit, inhibit calcium currents, thus decreasing the excitatory transmitter release and spinal sensitization. Gabapentinoids also activate the descending noradrenergic pain inhibitory system coupled to spinal α2 adrenoceptors. Gabapentinoid treatment may also indirectly impact on neuroimmune actors, like proinflammatory cytokines. These drugs are effective against neuropathic pain both with acute administration at high dose and with repeated administration. This review focuses on mechanistic knowledge concerning chronic antidepressant treatment and gabapentinoid treatment in a neuropathic pain context.

Cortical and subcortical gamma amino acid butyric acid deficits in anxiety and stress disorders: Clinical implications

Anxiety and stress disorders are a major public health issue. However, their pathophysiology is still unclear. The gamma amino acid butyric acid (GABA) neurochemical system has been strongly implicated in their pathogenesis and treatment by numerous preclinical and clinical studies, the most recent of which have been highlighted and critical review in this paper. Changes in cortical GABA appear related to normal personality styles and responses to stress. While there is accumulating animal and human neuroimaging evidence of cortical and subcortical GABA deficits across a number of anxiety conditions, a clear pattern of findings in specific brain regions for a given disorder is yet to emerge. Neuropsychiatric conditions with anxiety as a clinical feature may have GABA deficits as an underlying feature. Different classes of anxiolytic therapies support GABA function, and this may be an area in which newer GABA neuroimaging techniques could soon offer more personalized therapy. Novel GABAergic pharmacotherapies in development offer potential improvements over current therapies in reducing sedative and physiologic dependency effects, while offering rapid anxiolysis.

Metabolic and functional MR biomarkers of antiepileptic drug effectiveness: A review

As a large number of patients with epilepsy do not respond favorably to antiepileptic drugs (AEDs), a better understanding of treatment failure and the cause of adverse side effects is required. The working mechanisms of AEDs also alter neurotransmitter concentrations and brain activity, which can be measured using MR spectroscopy and functional MR imaging, respectively. This review presents an overview of clinical research of MR spectroscopy and functional MR imaging studies to the effects of AEDs on the brain. Despite the scarcity of studies associating MR findings to the effectiveness of AEDs, the current research shows clear potential regarding this matter. Several GABAergic AEDs have been shown to increase the GABA concentration, which was related to seizure reductions, while language problems due to topiramate have been associated with altered activation patterns measured with functional MR imaging. MR spectroscopy and functional MR imaging provide biomarkers that may predict individual treatment outcomes, and enable the assessment of mechanisms of treatment failure and cognitive side effects.

Temporal profile of brain response to alprazolam in patients with generalized anxiety disorder

This study investigated the temporal pattern of brain response to emotional stimuli during 28 days of alprazolam treatment among patients with generalized anxiety disorder (GAD) randomized 2:1 to drug or placebo in a double-blind design. Functional magnetic resonance imaging scans obtained during an emotion face matching task (EFMT) and an affective stimulus expectancy task (STIMEX) were performed at baseline, one hour after initial drug administration and 28 days later. Alprazolam significantly reduced scores on the Hamilton Anxiety Scale and the Penn State Worry Questionnaire after one week and 28 days of treatment. Brain activation in the amygdala during the EFMT and in the insula during the STIMEX was reduced one hour after alprazolam administration but returned to baseline levels at Day 28. Exploratory analyses revealed significant treatment differences in brain activity during the STIMEX on Day 28 in frontal lobe, caudate nucleus, middle temporal gyrus, secondary visual cortex, and supramarginal gyrus. These results are consistent with the notion that the neural mechanisms supporting sustained treatment effects of benzodiazepines in GAD differ from those underlying their acute effects.

Social status modulates the neural response to unfairness

In human society, which is organized by social hierarchies, resources are usually allocated unequally and based on social status. In this study, we analyze how being endowed with different social statuses in a math competition affects the perception of fairness during asset allocation in a subsequent Ultimatum Game (UG). Behavioral data showed that when participants were in high status, they were more likely to reject unfair UG offers than in low status. This effect of social status correlated with activity in the right anterior insula (rAI) and with the functional connectivity between the rAI and a region in the anterior middle cingulate cortex, indicating that these two brain regions are crucial for integrating contextual factors and social norms during fairness perception. Additionally, there was an interaction between social status and UG offer fairness in the amygdala and thalamus, implicating the role of these regions in the modulation of social status on fairness perception. These results demonstrate the effect of social status on fairness perception and the potential neural underpinnings for this effect.

Oxytocin's role in anxiety: a critical appraisal

A growing literature suggests that the oxytocin (OT) system may play a role in human anxiety states, anxiety-related traits, and moreover, that this system may be a target for the development of novel anxiolytic treatments. However, studies of OT's acute and chronic effects on various aspects of anxiety have produced mixed results. In this forward-looking review, we discuss the myriad phenomena to which the term "anxiety" is applied in the OT literature and the problem this presents developing a coherent picture of OT's role in anxiety. We then survey several different fields of research that support the role of the OT system in human anxiety, including evolutionary perspectives, translational and neuroimaging research, genetic studies, and clinical trials of intranasal OT. As an outgrowth of this data, we propose a "bowtie" model of OT's role at the interface of social attachment and anxiety. We next direct attention to understudied brain regions and neural circuits which may be important to study in OT experiments in humans anxiety disorders. Finally, we conclude by proposing questions and priorities for studying both the clinical potential of OT in anxiety, as well as mechanisms that may underlie this potential. Crucially, these priorities include targeted proof-of-concept clinical trials of IN OT in certain anxiety disorders, including investigations of individual moderators of OT's anxiolytic effects (i.e. sex, genetic factors, and early experience). This article is part of a Special Issue entitled Oxytocin and Social Behav.

Altered connectivity within the salience network during direct eye gaze in PTSD

BACKGROUND

Posttraumatic stress (PTSD) disorder has been associated with heightened threat sensitivity. Evidence suggests that direct eye gaze leads to sustained activation of the superior colliculus/periaqueductal grey within individuals with PTSD. The present analysis investigated functional connectivity within the salience network (SN) in the same sample as presented in a prior publication during direct versus averted gaze in adults with PTSD related to childhood maltreatment as compared to healthy individuals.

METHODS

Functional connectivity within the SN was examined using functional magnetic resonance imaging while participants viewed avatars positioned in direct versus averted gaze relative to the participant in 16 individuals with PTSD related to childhood maltreatment and 16 healthy control subjects. Connectivity within the SN was assessed via Independent Component Analysis (ICA). Associations with symptom severity were explored with multiple regression analyses on individual subject components.

RESULTS

Temporal multiple regression analyses revealed higher connectivity within the SN during direct versus averted gaze which was more pronounced in individuals with PTSD as compared to healthy controls. Compared to controls, individuals with PTSD showed increased integration of the left amygdala and the right insula within the SN. PTSD symptom severity was positively associated with connectivity of the right mid-cingulate cortex within the SN in PTSD subjects only.

CONCLUSIONS

Participants with PTSD showed enhanced coupling of the amygdala and the insula within the SN as compared to healthy control subjects during gaze processing. Our results provide evidence for an increased sensitivity of the salience network to direct versus averted gaze in individuals with PTSD related to childhood maltreatment.

Functional effects of chronic paroxetine versus placebo on the fear, stress and anxiety brain circuit in Social Anxiety Disorder: initial validation of an imaging protocol for drug discovery

Recent studies suggest that pharmacologic effects of anxiolytic agents can be mapped as functional changes in the fear, stress and anxiety brain circuit. In this work we investigated the effects of a standard treatment, paroxetine (20mg/day), in subjects with Social Anxiety Disorder (SAD) versus placebo using different fMRI paradigms. The fMRI sessions, performed before and after the treatment, consisted of a public exposition of recorded performance task (PERPT), an emotional face processing task (EFPT) and a 6-min resting state followed by an off-scanner public speaking test. Paroxetine significantly improved the clinical conditions of SAD patients (n=17) vs. placebo (n=16) as measured with Clinical Global Inventory - Improvement (CGI-I) while no change was seen when using Liebowitz Social Anxiety Scale, as expected given the small size of the study population. Paroxetine reduced the activation of insula, thalamus and subgenual/anterior cingulate cortex (ACC) in PERPT. Resting-state fMRI assessment using Independent Component Analysis indicated that paroxetine reduced functional connectivity in insula, thalamus and ACC when compared with placebo. Both paradigms showed significant correlation with CGI-I in rostral prefrontal cortex. Conversely, paroxetine compared to placebo produced activation of right amygdala and bilateral insula and no effects in ACC when tested with EFPT. No treatment effects on distress scores were observed in the off-scanner Public Speaking Test. Overall this study supports the use of fMRI as sensitive approach to explore the neurobiological substrate of the effects of pharmacologic treatments and, in particular, of resting state fMRI given its simplicity and task independence.

Neural responses during emotional processing before and after cognitive trauma therapy for battered women

Therapy for combat and accident-related posttraumatic stress disorder (PTSD) has been reported to influence amygdala and anterior cingulate cortex (ACC) response during emotional processing. It is not yet understood how therapy influences different phases of emotional processing, and whether previous findings generalize to other PTSD populations. We hypothesized that cognitive trauma therapy for battered women (CTT-BW) would alter insula, amygdala, and cingulate responses during anticipation and presentation of emotional images. Fourteen female patients with PTSD related to domestic violence completed the Clinician Administered PTSD Scale (CAPS) and functional magnetic resonance imaging (fMRI) before and after CTT-BW. The fMRI task involved cued anticipation followed by presentation of positive versus negative affective images. CTT-BW was associated with decreases in CAPS score, enhanced ACC and decreased anterior insula activation during anticipation, and decreased dorsolateral prefrontal cortex and amygdala response during image presentation (negative-positive). Pre-treatment ACC activation during anticipation and image presentation exhibited positive and negative relationships to treatment response, respectively. Results suggest that CTT-BW enhanced efficiency of neural responses during preparation for upcoming emotional events in a way that reduced the need to recruit prefrontal-amygdala responses during the occurrence of the event. Results also suggest that enhancing ACC function during anticipation may be beneficial for PTSD treatment.

The effect of psychological stress and expectation on auditory perception: A signal detection analysis

Both psychological stress and predictive signals relating to expected sensory input are believed to influence perception, an influence which, when disrupted, may contribute to the generation of auditory hallucinations. The effect of stress and semantic expectation on auditory perception was therefore examined in healthy participants using an auditory signal detection task requiring the detection of speech from within white noise. Trait anxiety was found to predict the extent to which stress influenced response bias, resulting in more anxious participants adopting a more liberal criterion, and therefore experiencing more false positives, when under stress. While semantic expectation was found to increase sensitivity, its presence also generated a shift in response bias towards reporting a signal, suggesting that the erroneous perception of speech became more likely. These findings provide a potential cognitive mechanism that may explain the impact of stress on hallucination-proneness, by suggesting that stress has the tendency to alter response bias in highly anxious individuals. These results also provide support for the idea that top-down processes such as those relating to semantic expectation may contribute to the generation of auditory hallucinations.

Pregabalin for the treatment of generalized anxiety disorder: an update

A PREVIOUS REVIEW SUMMARIZED WHAT WAS THEN KNOWN ABOUT THE POTENTIAL ROLE OF PREGABALIN IN THE TREATMENT OF PATIENTS WITH GENERALIZED ANXIETY DISORDER (GAD): this review provides an update on its pharmacological properties and presumed mechanism of action, the liability for abuse, and efficacy and tolerability in patients with GAD. Pregabalin has a similar molecular structure to the inhibitory neurotransmitter gamma amino butyric acid (GABA) but its mechanism of action does not appear to be mediated through effects on GABA. Instead, its anxiolytic effects may arise through high-affinity binding to the alpha-2-delta sub-unit of the P/Q type voltage-gated calcium channel in "over-excited" presynaptic neurons, thereby reducing the release of excitatory neurotransmitters such as glutamate. The findings of randomized controlled trials and meta-analyses together indicate that pregabalin is efficacious in both acute treatment and relapse prevention in GAD, with some evidence of an early onset of effect, and broad efficacy in reducing the severity of psychological and physical symptoms of anxiety. It also has efficacy as an augmenting agent after non-response to antidepressant treatment in GAD. Continuing vigilance is needed in assessing its potential abuse liability but the tolerability profile of pregabalin may confer some advantages over other pharmacological treatments in the short term for treatment in patients with GAD.

The diverse therapeutic actions of pregabalin: is a single mechanism responsible for several pharmacological activities?

Pregabalin is a specific ligand of the alpha2-delta (α2-δ) auxiliary subunit of voltage-gated calcium channels. A growing body of evidence from studies of anxiety and pain indicate that the observed responses with pregabalin may result from activity at the α2-δ auxiliary protein expressed presynaptically, in several different circuits of the central nervous system (CNS). The disorders that appear to be effectively treated with pregabalin are thematically linked by neuronal dysregulation or hyperexcitation within the CNS. This review proposes how binding to the α2-δ protein target in different regions of the CNS may contribute to the observed clinical activity of pregabalin, as well as to the adverse event profile of the compound. Whether this compound regulates synaptic function via α2-δ in additional conditions is yet to be discovered. The potential of pregabalin to regulate neuronal hyperactivity involving other CNS circuits will require further exploration.

Resting-state functional and structural connectivity within an insula-amygdala route specifically index state and trait anxiety

BACKGROUND

Conjoint activity of the insula and amygdala has frequently been reported during emotional stimulation in general and in anxiety-related contexts in particular. However, direct connectivity between the insula and amygdala in this framework has received little attention so far. Studying whether inter-individual differences in anxiety reflect variation in insula-amygdala connectivity is a way to push forward the understanding of network-related aspects underlying anxious behavior.

METHODS

To investigate functional and structural connectivity, we applied resting-state functional magnetic resonance imaging and diffusion tensor imaging in a group of 32 healthy subjects. Specific measures of connectivity between subregions of the insula and amygdala were related to subjects' anxiety levels.

RESULTS

Resting-state functional connectivity between the anterior insula and the basolateral amygdala was strongly related to state anxiety, explaining 40% of behavioral variance across subjects. This was substantiated by applying tractography, yielding a relationship between trait anxiety and axial diffusivity for a direct pathway between anterior insula and basolateral amygdala.

CONCLUSIONS

Our results indicate that anterior insula and basolateral amygdala constitute a network part that is prominently linked to anxiety. Within this route, state and trait behavioral impacts seem to be specifically linked to dynamic functional and more static structural neural aspects, respectively. Insula-amygdala resting-state functional connectivity can be assessed in an easy and straightforward way and has high potential to serve as a biomarker for anxiety.

Neural dysregulation in posttraumatic stress disorder: evidence for disrupted equilibrium between salience and default mode brain networks

OBJECTIVE

Convergent research demonstrates disrupted attention and heightened threat sensitivity in posttraumatic stress disorder (PTSD). This might be linked to aberrations in large-scale networks subserving the detection of salient stimuli (i.e., the salience network [SN]) and stimulus-independent, internally focused thought (i.e., the default mode network [DMN]).

METHODS

Resting-state brain activity was measured in returning veterans with and without PTSD (n = 15 in each group) and in healthy community controls (n = 15). Correlation coefficients were calculated between the time course of seed regions in key SN and DMN regions and all other voxels of the brain.

RESULTS

Compared with control groups, participants with PTSD showed reduced functional connectivity within the DMN (between DMN seeds and other DMN regions) including the rostral anterior cingulate cortex/ventromedial prefrontal cortex (z = 3.31; p = .005, corrected) and increased connectivity within the SN (between insula seeds and other SN regions) including the amygdala (z = 3.03; p = .01, corrected). Participants with PTSD also demonstrated increased cross-network connectivity. DMN seeds exhibited elevated connectivity with SN regions including the insula (z = 3.06; p = .03, corrected), and SN seeds exhibited elevated connectivity with DMN regions including the hippocampus (z = 3.10; p = .048, corrected).

CONCLUSIONS

During resting-state scanning, participants with PTSD showed reduced coupling within the DMN, greater coupling within the SN, and increased coupling between the DMN and the SN. Our findings suggest a relative dominance of threat-sensitive circuitry in PTSD, even in task-free conditions. Disequilibrium between large-scale networks subserving salience detection versus internally focused thought may be associated with PTSD pathophysiology.

Pregabalin for alcohol dependence: a critical review of the literature

INTRODUCTION

Alcohol dependence represents a severe pathological disorder associated with a significant rate of morbidity and mortality. To date, limited pharmacological agents exist to treat this disorder, and there is a growing interest for new therapies. In this context, pregabalin represents a promising strategy. Pregabalin, like gabapentin, selectively binds to the α(2)δsubunit of voltage-gated calcium channels, inhibiting release of excessive levels of excitatory neurotransmitters. The main focus of this review is the clinical use of pregabalin in alcoholic patients, but the authors also reported some data about chemistry, pharmacology, and pharmacokinetics of this drug.

METHODS

The authors conducted a PubMed search of clinical human studies published in English from January 2000 to August 2012 using the following search terms: pregabalin alcohol dependence, pregabalin alcohol withdrawal, pregabalin alcoholism.

RESULTS

The search revealed a total of five studies: two trials for the treatment of alcohol relapse and three articles for the management of alcohol withdrawal syndrome with pregabalin. The critical review of the literature suggests that pregabalin could be a novel and effective treatment option for the management of alcohol relapse in detoxified patients, whereas until now there have been mixed results for the treatment of alcohol withdrawal syndrome. In particular, pregabalin showed a greater beneficial effect on patients with comorbid conditions such as alcoholism and generalized anxiety disorders. The exact mechanism of action of pregabalin in the management of alcoholism is not well understood but it is thought to be due mainly to the modulation of neurotransmitters such as glutamate and norepinephrine by inhibiting activity-dependent calcium influx in nerve terminals.

CONCLUSION

Pregabalin, within a dosage of 150-450 mg/day, showed beneficial effects for alcohol relapse prevention and contrasting results for the treatment of the withdrawal syndrome. Its use appears to be safe and well tolerated.

Asymmetric time-dependent activation of right central amygdala neurones in rats with peripheral neuropathy and pregabalin modulation

Neuropathic pain (NP) often presents with comorbidities, including depression and anxiety. The amygdala is involved in the processing of mood disorders, fear, and the emotional-affective components of pain. Hemispheric lateralization of pain processing in the amygdala has recently been brought to light because, independently of the side of the peripheral injury, the right central nucleus of the amygdala (CeA) showed higher neuronal activity than the left in models of inflammatory pain. Although the CeA has been called the 'nociceptive amygdala', because of its high content of nociceptive neurones, little is known about changes in its neuronal function in vivo, under NP conditions. Herein, we quantified CeA spontaneous and evoked activity in rats subjected to spinal nerve ligation (SNL), under isoflurane anaesthesia, following application of mechanical and thermal stimuli to widespread body areas. We found that spontaneous and stimulus-evoked neuronal activity was higher in the left CeA at 2 and 6 days after SNL induction and declined afterwards, whereas activity in the right CeA became dominant at 14 days after surgery, independently of the side of surgery. We also observed that systemic injection of pregabalin, which is widely used in patients with NP, reduced CeA spontaneous and stimulus-evoked neuronal activity. Overall, we observed that peripheral nerve injury produced asymmetric plasticity in ongoing and evoked activity in the left and right CeA. Remarkably, at 14 days after SNL induction, enhanced evoked activity in the right CeA persisted compared to short-term increases in activity in the left CeA. The plasticity found in ongoing and evoked activity was inhibited by pregabalin.

Elucidating the mechanism of action of pregabalin: α(2)δ as a therapeutic target in anxiety

This review provides a brief summary of what is known about the anxiolytic mechanism of action of pregabalin, a highly selective, high-affinity ligand of the P/Q type of voltage-gated calcium channel (CaV). Evidence from in vivo models of neuronal hyperexcitability suggests that pregabalin reduces synaptic release of neurotransmitters in selected CNS regions including the cortex, olfactory bulb, hypothalamus, amygdala, hippocampus, cerebellum and dorsal horn of the spinal cord. Release of neurotransmitters from the synaptic vesicle, and propagation of neurotransmission, requires the vesicle to fuse with the presynaptic membrane. Pregabalin binding to the α(2)δ type 1 protein of the P/Q type CaV reduces the availability of Ca2+ required for membrane fusion and exocytosis of neurotransmitters. Evidence that the anxiolytic mechanism of action of pregabalin is mediated by binding to the α(2)δ type 1 protein comes from animal models, which have demonstrated a structure-activity relationship between the affinity of ligands for the α(2)δ type 1 protein and their potency in models of anxiety such as the Vogel conflict test. Furthermore, the anxiolytic activity of pregabalin is lost in transgenic mice with specific point mutations in the CaV α(2)δ type 1 protein. Pregabalin-mediated reduction in calcium currents has also been shown to result in a significant inhibition of the release of neurotransmitters implicated in pathological anxiety such as glutamate and monoamine neurotransmitters. However, further research is needed to confirm that these effects contribute to the anxiolytic mechanism of action of pregabalin. Finally, pregabalin may also act by inhibiting synaptogenesis of excitatory neurons formed in response to chronic stress or anxiety, or more acutely inhibit the trafficking of CaV to the plasma membrane.

Effects of anxiolytic treatment on potentiated startle during aversive image anticipation

OBJECTIVE

Heightened anticipation of future events has been characterized as a feature of certain anxiety disorders. In functional magnetic resonance imaging studies, anticipation of fearful/threatening images has been shown to robustly activate the insular cortex and amygdala in healthy subjects, in subjects with high trait anxiety, and in some with anxiety disorders. Blood oxygenation level dependent activation in response to negative image anticipation is also sensitive to anxiolytic treatment, suggesting that image anticipation probes anxiety systems. It is not clear, however, if behavioral responses to image anticipation are also sensitive to anxiolytics. This study tested the hypothesis that anxiety behaviors during anticipation of negative images are sensitive to anxiolytic treatment.

METHOD

This study examined the effects of alprazolam and pregabalin treatment on potentiated startle during affective image anticipation.

RESULTS

There was an effect of anticipation type (negative versus neutral versus positive) on startle reactivity and subjective ratings, suggesting that the task was effective in assaying negative anticipatory arousal. Both treatments significantly reduced overall startle magnitude. However, neither treatment specifically affected potentiated startle during aversive anticipation.

CONCLUSION

These data suggest that potentiated startle in response to anticipation of aversive images is not sensitive to anxiolytic treatments in a healthy population, limiting its use as a predictive model of anxiolytic activity. This article is a US Government work and is in the public domain in the USA.

Efficacy and safety of pregabalin in the treatment of alcohol and benzodiazepine dependence

INTRODUCTION

Both alcohol and benzodiazepine dependence (AD, BD) are severe and chronic conditions with devastating physical and mental health effects. The relative scarcity and controversial evidential status of available pharmacological interventions for the treatment of patients' acute withdrawal syndrome and/or relapse prevention call for the clinical investigation of novel safe and efficacious agents.

AREAS COVERED

We review published studies of pregabalin as monotherapy in the treatment of AD and BD in more than 450 patients. Available evidence includes four RCTs, two in AD with active comparator drugs (naltrexone, tiapride, and lorazepam) and one placebo-controlled, and one placebo-controlled in BD. We also review other available studies on pregabalin's potential to reduce benzodiazepine consumption, its side effects, especially cognitive, as well as extant reports on its liability for abuse.

EXPERT OPINION

Available evidence suggests that monotherapy with pregabalin, within the dosage range of 150 - 600 mg/d, is a promising "novel" option for the safe and efficacious relapse prevention of both AD and BD. However, its efficacy as monotherapy in the acute treatment of AD withdrawal syndrome is still controversial. Clinicians should be cautious in prescribing pregabalin to patients with a history of multiple substance recreational use, and monitor its effects on cognition at dosages above 450 mg/d. Further, well-designed clinical research is still needed for the eventual consolidation of pregabalin's place in the treatment of AD and BD.

The effect of pregabalin on sensorimotor gating in 'low' gating humans and mice

Pregabalin, an anticonvulsant and anxiolytic compound that binds to α2-δ auxiliary subunit Types 1 and 2 of voltage-gated calcium channels, has been shown to reduce excitatory neurotransmission partially through modulation of glutamatergic signaling. Prepulse inhibition (PPI) of startle is an operational measure of sensorimotor gating impacted by disruption of the glutamatergic system and is reduced in schizophrenia patients. Dysregulation of the glutamatergic system has also been implicated in the pathophysiology of schizophrenia. Here we tested the hypothesis that pregabalin may ameliorate PPI in a model of deficient gating in humans and mice. In study 1, 14 healthy human subjects participated in a within subjects, cross-over study with placebo, 50 mg or 200 mg pregabalin treatment prior to undergoing a PPI task. In study 2, 24 C57BL/6 mice underwent a similar procedure with vehicle, 30 and 100 mg/kg dose treatments. In both studies, subjects were assigned to a "Low" or "High" gating group using a median split procedure based on their PPI performance during placebo/vehicle. Drug effects were then examined across these groups. In humans, pregabalin treatment significantly increased PPI performance in the "low gating" group. In mice, pregabalin treatment significantly increased PPI in the low gating group but reduced PPI in the high gating group. Across species, pregabalin treatment improves PPI in subjects with low gating. These data support further exploration of pregabalin as a potential treatment for disorders characterized by sensorimotor gating deficits and glutamatergic hypersignaling, such as schizophrenia.

Pregabalin effects on neural response to emotional faces

Pregabalin has shown promise in the treatment of anxiety disorders. Previous functional magnetic resonance imaging (fMRI) studies indicate agents used to treat anxiety, e.g., SSRIs and benzodiazepines, attenuate amygdala, insula, and medial prefrontal cortex (mPFC) activation during emotional processing. Our prior study has shown that during anticipation of an emotional stimulus, pregabalin attenuates amygdala and insula activation but increases medial PFC activation. In this study, we examined whether, similar to SSRIs and benzodiazepines, pregabalin attenuates amygdala, insula, and medial PFC during emotional face processing. Sixteen healthy volunteers underwent a double-blind within-subjects fMRI study investigating effects of placebo, 50 mg, and 200 mg pregabalin on neural activation during an emotional face-matching task. Linear mixed model analysis revealed that pregabalin dose-dependently attenuated left amygdala activation during fearful face-matching and left anterior insula activation during angry face-matching. The 50 mg dose exhibited more robust effects than the 200 mg dose in the right anterior insula and ventral ACC. Thus, pregabalin shares some similarity to SSRIs and benzodiazepines in attenuating anger and fear-related insula and amygdala activation during emotional face processing. However, there is evidence that a subclinical 50 mg dose of pregabalin produced more robust and widespread effects on neural responses in this paradigm than the more clinically relevant 200 mg dose. Taken together, pregabalin has a slightly different effect on brain activation as it relates to anticipation and emotional face processing, which may account for its unique characteristic as an agent for the treatment of anxiety disorders.

Neuroimaging in anxiety disorders

Over the last few years, neuroimaging techniques have contributed greatly to the identification of the structural and functional neuroanatomy of anxiety disorders. The amygdala seems to be a crucial structure for fear and anxiety, and has consistently been found to be activated in anxiety-provoking situations. Apart from the amygdala, the insula and anterior cinguiate cortex seem to be critical, and all three have been referred to as the “fear network.” In the present article, we review the main findings from three major lines of research. First, we examine human models of anxiety disorders, including fear conditioning studies and investigations of experimentally induced panic attacks. Then we turn to research in patients with anxiety disorders and take a dose look at post-traumatic stress disorder and obsessive-compulsive disorder. Finally, we review neuroimaging studies investigating neural correlates of successful treatment of anxiety, focusing on exposure-based therapy and several pharmacological treatment options, as well as combinations of both.

Decreased startle modulation during anticipation in the postpartum period in comparison to late pregnancy

Knowledge about healthy women’s psychophysiological adaptations during the large neuroendocrine changes of pregnancy and childbirth is essential in order to understand why these events have the potential to disrupt mental health in vulnerable individuals. This study aimed to compare startle response modulation, an objective psychophysiological measure demonstrated to be influenced by anxiety and depression, longitudinally across late pregnancy and the postpartum period. The acoustic startle response modulation was assessed during anticipation of affective images and during image viewing in 31 healthy women during gestational weeks 36–39 and again at 4 to 6 weeks postpartum. No startle modulation by affective images was observed at either time point. Significant modulation during anticipation stimuli was found at pregnancy assessment but was reduced in the postpartum period. The women rated the unpleasant images more negative and more arousing and the pleasant images more positive at the postpartum assessment. Self-reported anxiety and depressive symptoms did not change between assessments. The observed postpartum decrease in modulation of startle by anticipation suggests a relatively deactivated defense system in the postpartum period.

Anxiolytic-like effect of pregabalin on unconditioned fear in the rat: an autoradiographic brain perfusion mapping and functional connectivity study

Clinical and preclinical evidence suggests anxiolytic-like efficacy of pregabalin (PGB, Lyrica). However, its mechanism of action remains under investigation. The current study applied [(14)C]-iodoantipyrine cerebral blood flow (CBF) mapping to examine the effect of PGB on neural substrates underlying unconditioned fear in a rat model of footshock-induced fear. Regional CBF (rCBF) was analyzed by statistical parametric mapping. Functional connectivity and graph theoretical analysis were used to investigate how footshock and PGB affect brain activation at the network level. Pregabalin significantly attenuated footshock-induced ultrasonic vocalization, but showed no significant effect on freezing behavior. Footshock compared to no-shock controls elicited significant increases in rCBF in limbic/paralimbic regions implicated in the processing of unconditioned fear and ultrasonic vocalization, including the amygdala, hypothalamus, lateral septum, dorsal periaqueductal gray, the anterior insular (aINS) and medial prefrontal cortex (mPFC). The activation pattern was similar in vehicle- and PGB-treated subjects, with PGB significantly attenuating activation in the amygdala, hypothalamus, and aINS. The vehicle/no-shock group showed strong, positive intra-structural correlations within the cortex, hypothalamus, amygdala, thalamus, and brainstem. The cortex was negatively correlated with the hypothalamus and brainstem. Footshock reduced the total number of significant correlations, but induced greater intra-cortical connectivity of the aINS and mPFC, and new positive correlations between the hypothalamus and amygdala. In no-shock controls, PGB significantly reduced the positive intra-structural correlations within the cortex and amygdala, as well as the negative cortico-subcortical correlations. Following footshocks, PGB disrupted both the network recruitment of aINS and mPFC, and the positive hypothalamic-amygdaloid correlations. Our findings suggest that PGB may exert anxiolytic effect by attenuating cortico-cortical and cortico-subcortical communication and inhibiting network recruitment of the aINS, mPFC, amygdala, and hypothalamus following a fear-inducing stimulus. Functional brain mapping in rodents may provide new endpoints for preclinical evaluation of anxiolytic drug candidates with potentially improved translational power compared to behavioral measurements alone.