Fear and the Amygdala: Manipulation of Awareness Generates Differential Cerebral Responses to Phobic and Fear-Relevant (but Nonfeared) Stimuli

Feasibility and acceptability of an online group dialectical behavioural therapy skills training in a Transdiagnostic group with Anxiety and Depression

Transdiagnostic approaches offers a paradigm shift in managing psychiatric disorders. Emotion regulation difficulties are a transdiagnostic prevalent across various mood and personality disorders. Dialectical Behavioural Therapy Skills Training (DBT-ST), initially designed as part of treatment for borderline personality disorder, targets emotion regulation and has shown promise in diverse psychiatric conditions. In lower middle-income countries with resource-constrained settings, online delivery of evidence-based interventions holds potential to bridge treatment gaps. This study assesses the feasibility and acceptability of online group DBT skills training for individuals with depression or anxiety disorders in India. Mental health professionals practising in India referred twenty-four eligible participants currently not engaged in psychotherapy. Of these, 18 initiated the 8-week virtual group DBT-ST program, with 12 completing it (66 % female, 18-35 years of age, 5 on concurrent medication). They provided feedback on therapy content's usefulness. Baseline, post-intervention, and one-month follow-up assessments measured changes in emotion regulation difficulties, depression, and anxiety symptoms. Treatment retained 66.7 % of participants, all participants found the intervention beneficial. Repeated measures ANOVA indicates significant reductions in self-reported difficulties in emotion regulation, depression, and anxiety symptoms post-intervention. These findings highlight the promise of transdiagnostic interventions like DBT-ST that merit further evaluations using RCTs with larger sample sizes.

Advancing the treatment of anxiety disorders in transition-age youth: a review of the therapeutic effects of unconscious exposure

BACKGROUND

The real-world effectiveness of exposure-based therapies for youth depends on the willingness and ability of young people to tolerate confronting their fears, which can be experienced as highly aversive and create problems with treatment engagement and acceptance. Recently, neuroscientific research on the nonconscious basis of fear has been translated into novel exposure interventions that bypass conscious processing of feared stimuli and that thus do not cause phobic youth to experience distress. We present a review of these unconscious exposure interventions.

METHODS

A PRISMA-based search yielded 20 controlled experiments based on three paradigms that tested if fear-related responses could be reduced without conscious awareness in highly phobic, transition-age youth: 14 randomized controlled trials (RCTs), 5 fMRI studies (1 was also an RCT), 4 psychophysiological studies (3 were also RCTs), and 1 ERP study. We conducted meta-analyses of outcomes where feasible.

RESULTS

Unconscious exposure interventions significantly (1) reduced avoidance behavior (range of Cohen's d = 0.51-0.95) and self-reported fear (d = 0.45-1.25) during in vivo exposure to the feared situation; (2) reduced neurobiological indicators of fear (d = 0.54-0.62) and concomitant physiological arousal (d = 0.55-0.64); (3) activated neural systems supporting fear regulation more strongly than visible exposure to the same stimuli (d = 1.2-1.5); (4) activated regions supporting fear regulation that mediated the reduction of avoidance behavior (d = 0.70); (5) evoked ERPs suggesting encoding of extinction memories (d = 2.13); and (6) had these effects without inducing autonomic arousal or subjective fear.

CONCLUSIONS

Unconscious exposure interventions significantly reduce a variety of symptomatic behaviors with mostly moderate effect sizes in transition-age youth with specific phobias. fMRI and physiological findings establish a neurophysiological basis for this efficacy, and suggest it occurs through extinction learning. Unconscious exposure was well tolerated, entirely unassociated with drop out, and is highly scalable for clinical practice. However, a number of limitations must be addressed to assess potential clinical impacts, including combining unconscious exposure with exposure therapy to boost treatment acceptance and efficacy.

Binocularly suppressed stimuli induce brain activities related to aesthetic emotions

Introduction

Aesthetic emotions are a class of emotions aroused by evaluating aesthetically appealing objects or events. While evolutionary aesthetics suggests the adaptive roles of these emotions, empirical assessments are lacking. Previous neuroscientific studies have demonstrated that visual stimuli carrying evolutionarily important information induce neural responses even when presented non-consciously. To examine the evolutionary importance of aesthetic emotions, we conducted a neuroscientific study using magnetoencephalography (MEG) to measure induced neural responses to non-consciously presented portrait paintings categorised as biological and non-biological and examined associations between the induced responses and aesthetic ratings.

Methods

MEG and pre-rating data were collected from 23 participants. The pre-rating included visual analogue scales for object saliency, facial saliency, liking, and beauty scores, in addition to 'biologi-ness,' which was used for subcategorising stimuli into biological and non-biological. The stimuli were presented non-consciously using a continuous flash suppression paradigm or consciously using binocular presentation without flashing masks, while dichotomic behavioural responses were obtained (beauty or non-beauty). Time-frequency decomposed MEG data were used for correlation analysis with pre-rating scores for each category.

Results

Behavioural data revealed that saliency scores of non-consciously presented stimuli influenced dichotomic responses (beauty or non-beauty). MEG data showed that non-consciously presented portrait paintings induced spatiotemporally distributed low-frequency brain activities associated with aesthetic ratings, which were distinct between the biological and non-biological categories and conscious and non-conscious conditions.

Conclusion

Aesthetic emotion holds evolutionary significance for humans. Neural pathways are sensitive to visual images that arouse aesthetic emotion in distinct ways for biological and non-biological categories, which are further influenced by consciousness. These differences likely reflect the diversity in mechanisms of aesthetic processing, such as processing fluency, active elaboration, and predictive processing. The aesthetic processing of non-conscious stimuli appears to be characterised by fluency-driven affective processing, while top-down regulatory processes are suppressed. This study provides the first empirical evidence supporting the evolutionary significance of aesthetic processing.

Exploring the use of visual predictions in social scenarios while under anticipatory threat

One of the less recognized effects of anxiety lies in perception alterations caused by how one weighs both sensory evidence and contextual cues. Here, we investigated how anxiety affects our ability to use social cues to anticipate the others' actions. We adapted a paradigm to assess expectations in social scenarios, whereby participants were asked to identify the presence of agents therein, while supported by contextual cues from another agent. Participants (N = 66) underwent this task under safe and threat-of-shock conditions. We extracted both criterion and sensitivity measures as well as gaze data. Our analysis showed that whilst the type of action had the expected effect, threat-of-shock had no effect over criterion and sensitivity. Although showing similar dwell times, gaze exploration of the contextual cue was associated with shorter fixation durations whilst participants were under threat. Our findings suggest that anxiety does not appear to influence the use of expectations in social scenarios.

Emotional processing impairments in patients with insula lesions following stroke

Functional imaging has helped to understand the role of the human insula as a major processing network for integrating input with the current state of the body. However, these studies remain at a correlative level. Studies that have examined insula damage show lesion-specific performance deficits. Case reports have provided anecdotal evidence for deficits following insula damage, but group lesion studies offer a number of advances in providing evidence for functional representation of the insula. We conducted a systematic literature search to review group studies of patients with insula damage after stroke and identified 23 studies that tested emotional processing performance in these patients. Eight of these studies assessed emotional processing of visual (most commonly IAPS), auditory (e.g., prosody), somatosensory (emotional touch) and autonomic function (heart rate variability). Fifteen other studies looked at social processing, including emotional face recognition, gaming tasks and tests of empathy. Overall, there was a bias towards testing only patients with right-hemispheric lesions, making it difficult to consider hemisphere specificity. Although many studies included an overlay of lesion maps to characterise their patients, most did not differentiate lesion statistics between insula subunits and/or applied voxel-based associations between lesion location and impairment. This is probably due to small group sizes, which limit statistical comparisons. We conclude that multicentre analyses of lesion studies with comparable patients and performance tests are needed to definitively test the specific function of parts of the insula in emotional processing and social interaction.

Preliminary evidence for the acceptability, safety, and efficacy of the flash technique

Objectives

This study reports on four similar studies intended to explore the acceptability, safety, and efficacy of the flash technique (FT), a method of rapidly reducing the intensity of a disturbing memory or image, with minimal subjective disturbance for subjects during the process. Of the four studies, two were conducted during FT trainings in the United States, one in Australia, and one in Uganda.

Methods

The studies involve pre-, post-, and follow-up repeated-measures design to determine the effectiveness of a 15-min FT intervention. A total of 654 subjects were asked to think of a disturbing memory and then participate in a structured experience of an FT. The purpose of this investigation was to determine whether a brief application of an FT would be safe and effective in significantly reducing their disturbance. In each study, subjects rated their disturbing memories on a 0-to-10 scale, with zero representing no disturbance at all and 10 representing the worst they could imagine. Then, they took part in a 15-min group practicum where they were guided in a self-administering FT with no individual supervision or support.

Results

In all four studies, the mean reduction in disturbance exceeded two-thirds, the results were significant (p < 0.001), and the effect size was very large. Of the 813 sessions (654 subjects) represented in these studies, only two subjects reported slight increases in disturbances, and both of these subjects reported reductions in disturbance in their second FT experiences 2 h later. At a 4-week follow-up, mean disturbance levels in all four studies indicated maintenance of benefit or slightly further reduction of mean disturbance levels. An 18-month follow-up study with a subgroup of subjects who initially reported a high level of memory-related distress found similar maintenance of gains as well as symptom reduction.

Conclusion

These findings provide preliminary evidence of acceptability, safety, and efficacy of FT; therefore, further study is warranted.

Alternation in functional connectivity within default mode network after psychodynamic psychotherapy in borderline personality disorder

BACKGROUND

Borderline personality disorder (BPD) is characterized by impairments in emotion regulation, impulse control, and interpersonal and social functioning along with a deficit in emotional awareness and empathy. In this study, we investigated whether functional connectivity (FC) within the default mode network (DMN) is affected by 1-year psychodynamic psychotherapy in patients with BPD.

METHODS

Nine BPD patients filled out the demography, Interpersonal Reactive Index (IRI), Toronto Alexithymia Scale 20 (TAS 20), the Alcohol, Smoking, and Substance Involvement Screening Test (ASSIST), and the Borderline Evaluation Severity over Time (BEST) questionnaire. The BPD group (9F) and the control group (9F) had a mean ± SD age of 28.2 ± 5.3 years and 30.4 ± 6.1 years, respectively. BPD subjects underwent longitudinal resting-state fMRI before psychodynamic psychotherapy and then every 4 months for a year after initiating psychotherapy. FC in DMN was characterized by calculating the nodal degree, a measure of centrality in the graph theory.

RESULTS

The results indicated that patients with BPD present with aberrant DMN connectivity compared to healthy controls. Over a year of psychotherapy, the patients with BPD showed both FC changes (decreasing nodal degree in the dorsal anterior cingulate cortex and increasing in other cingulate cortex regions) and behavioral improvement in their symptoms and substance use. There was also a significant positive association between the decreased nodal degree in regions of the dorsal cingulate cortex and a decrease in the score of the TAS-20 indicating difficulty in identifying feelings after psychotherapy.

CONCLUSION

In BPD, there is altered FC within the DMN and disruption in self-processing and emotion regulation. Psychotherapy may modify the DMN connectivity and that modification is associated with positive changes in BPD emotional symptoms.

Can the aberrant occipital-cerebellum network be a predictor of treatment in panic disorder?

BACKGROUND

This study aimed to detect altered brain activation pattern of patients with panic disorder (PD) and its changes after treatment. The possibilities of diagnosis and prediction of treatment response based on the aberrant brain activity were tested.

METHODS

Fifty-four PD patients and 54 healthy controls (HCs) were recruited. Clinical assessment and resting-state functional magnetic resonance imaging scans were conducted. Then, patients received a 4-week paroxetine treatment and underwent a second clinical assessment and scan. The fractional amplitude of low-frequency fluctuations (fALFF) was measured. Support vector machine (SVM) and support vector regression (SVR) analyses were conducted.

RESULTS

Lower fALFF values in the right calcarine/lingual gyrus and left lingual gyrus/cerebellum IV/V, whereas higher fALFF values in right cerebellum Crus II were observed in patients related to HCs at baseline. After treatment, patients with PD exhibited significant clinical improvement, and the abnormal lower fALFF values in the right lingual gyrus exhibited a great increase. The abnormal fALFF at pretreatment can distinguish patients from HCs with 80 % accuracy and predict treatment response which was reflected in the significant correlation between the predicted and actual treatment responses.

LIMITATIONS

The impacts of ethnic, cultural, and other regional differences on PD were not considered for it was a single-center study.

CONCLUSIONS

The occipital-cerebellum network played an important role in the pathophysiology of PD and should be a part of the fear network. The abnormal fALFF values in patients with PD at pretreatment could serve as biomarkers of PD and predict the early treatment response of paroxetine.

Navigating the impact of workplace distractions for persons with TBI: a qualitative descriptive study

Persons with traumatic brain injuries (TBIs) who return to work often struggle with managing environmental distractions due to residual cognitive impairments. Previous literature has established that environmental distractions impact persons with TBI, yet, the extent to which distractions impact workplace performance is unknown. This qualitative descriptive study using phenomenology methods, explored the experiences of seven individuals with TBIs and how they perceived workplace distractions to impact their productivity. Data was collected using semi-structured interviews with seven participants who were diagnosed with mild, moderate, and severe TBIs. Interviews were transcribed and analyzed using thematic analysis. Main findings centered around what environmental distractions impacted work performance, the farther-reaching consequences of distractibility, strong emotional feelings and worry about perceived work performance associated with distractibility, mitigating distractibility through “gaming the attentional system”, and utilizing music as a distraction masker to enhance task performance. In light of this study’s findings, researchers, and clinicians are encouraged to consider the wider impact of distractions on persons with TBI. The real-life accounts documented in this study will assist researchers and clinicians to account for the impact of environmental distractions in rehabilitation and support employment for persons with TBI.

Nothing to Fear but Fear Itself: A Mechanistic Test of Unconscious Exposure

BACKGROUND

While effective, exposure therapy can be distressing, which creates problems with treatment acceptance. Can exposure be effectively delivered unconsciously-and thus without causing phobic people to experience distress? No study has tested this hypothesis in a sufficiently rigorous experiment that selected between mechanisms for reducing fear unconsciously.

METHODS

We conducted a psychophysiological experiment of an unconscious exposure intervention to discern its mechanism of therapeutic action. We identified 98 highly spider-phobic participants with a validated fear questionnaire and a Behavioral Avoidance Test in which they gradually approached and exhibited impairment of a live tarantula, which was indicative of a DSM-5 diagnosis of specific phobia. These participants were randomized to viewing unconscious exposure to spiders, visible exposure to spiders, or unconscious exposure to flowers (control). In a novel psychophysiological design, concurrent changes in sympathetic arousal and subjective fear were monitored throughout exposure. Shortly thereafter, phobic participants approached the tarantula again in order to measure exposure-induced changes in real-life avoidance behavior and experienced fear.

RESULTS

Unconscious exposure did not induce concurrent changes in sympathetic arousal or subjective fear, and subsequently reduced fear of the tarantula. Visible exposure to the same phobic stimuli, by contrast, induced significant arousal and fear, but did not affect fear of the tarantula. Levels of arousal during exposure moderated effects on fear of the tarantula: lower arousal during unconscious exposure, but not during conscious exposure, predicted greater fear reduction.

CONCLUSIONS

Unconscious exposure reduces fear by generating new implicit learning of nonaversive, stimulus-response associations that facilitate fear extinction in phobic persons.

Systematic Review of Studies on Subliminal Exposure to Phobic Stimuli: Integrating Therapeutic Models for Specific Phobias

We systematically review 26 papers investigating subjective, behavioral, and psychophysiological correlates of subliminal exposure to phobic stimuli in phobic patients. Stimulations were found to elicit: (1) cardiac defense responses, (2) specific brain activations of both subcortical (e.g., amygdala) and cortical structures, (3) skin conductance reactions, only when stimuli lasted >20 ms and were administered with intertrial interval >20 s. While not inducing the distress caused by current (supraliminal) exposure therapies, exposure to subliminal phobic stimuli still results in successful extinction of both psychophysiological and behavioral correlates: however, it hardly improves subjective fear. We integrate those results with recent bifactorial models of emotional regulation, proposing a new form of exposure therapy whose effectiveness and acceptability should be maximized by a preliminary subliminal stimulation. Systematic Review Registration: identifier [CRD42021129234].

Conscious and unconscious brain responses to food and cocaine cues

Visual presentation of appetitive and negative cues triggers fast responses in the human brain. Here we assessed functional MRI (fMRI) responses to food, cocaine, and neutral cues presented at a subliminal ("unconscious", 33 ms) and supraliminal ("conscious", 750 and 3000 ms) level in healthy, cocaine naïve volunteers. Because there is evidence of circadian variability in reward sensitivity, our second aim was to assess diurnal variability in the brain's reactivity to cues. Sixteen participants completed two randomly ordered fMRI sessions (once 9-11 AM and another 5-7 PM). in which food, cocaine, and neutral cues were presented for 33, 750 and 3000 ms. Participants rated food cues as positive and "wanted" (more so in evenings than mornings), and cocaine cues as negative (no diurnal differences). fMRI showed occipital cortex activation for food>neutral, cocaine>neutral and cocaine>food; dorsolateral prefrontal cortex for cocaine>neutral and cocaine>food, and midbrain for cocaine>food (all p_FWE < 0.05). When comparing unconscious (33 ms) > conscious (750 and 3000 ms) presentations, we observed significant differences for cocaine>neutral and cocaine>food in occipital cortex, for cocaine>neutral in the insula/temporal lobe, and for food>neutral in the middle temporal gyrus (p_FWE < 0.05). No diurnal differences for brain activations were observed. We interpret these findings to suggest that negative items (e.g., cocaine) might be perceived at a faster speed than positive ones (e.g., food), although we cannot rule out that the higher saliency of cocaine cues, which would be novel to non-drug using individuals, contributed to the faster speed of detection.

Preferential Neuronal Responses to Snakes in the Monkey Medial Prefrontal Cortex Support an Evolutionary Origin for Ophidiophobia

Ophidiophobia (snake phobia) is one of the most common specific phobias. It has been proposed that specific phobia may have an evolutionary origin, and that attentional bias to specific items may promote the onset of phobia. Noninvasive imaging studies of patients with specific phobia reported that the medial prefrontal cortex (mPFC), especially the rostral part of the anterior cingulate cortex (rACC), and amygdala are activated during the presentation of phobogenic stimuli. We propose that the mPFC-amygdala circuit may be involved in the pathogenesis of phobia. The mPFC receives inputs from the phylogenically old subcortical visual pathway including the superior colliculus, pulvinar, and amygdala, while mPFC neurons are highly sensitive to snakes that are the first modern predator of primates, and discriminate snakes with striking postures from those with non-striking postures. Furthermore, the mPFC has been implicated in the attentional allocation and promotes amygdala-dependent aversive conditioning. These findings suggest that the rACC focuses attention on snakes, and promotes aversive conditioning to snakes, which may lead to anxiety and ophidiophobia.

Repetition of Computer Security Warnings Results in Differential Repetition Suppression Effects as Revealed With Functional MRI

Computer users are often the last line of defense in computer security. However, with repeated exposures to system messages and computer security warnings, neural and behavioral responses show evidence of habituation. Habituation has been demonstrated at a neural level as repetition suppression where responses are attenuated with subsequent repetitions. In the brain, repetition suppression to visual stimuli has been demonstrated in multiple cortical areas, including the occipital lobe and medial temporal lobe. Prior research into the repetition suppression effect has generally focused on a single repetition and has not examined the pattern of signal suppression with repeated exposures. We used complex, everyday stimuli, in the form of images of computer programs or security warning messages, to examine the repetition suppression effect across repeated exposures. The use of computer warnings as stimuli also allowed us to examine the activation of learned fearful stimuli. We observed widespread linear decreases in activation with repeated exposures, suggesting that repetition suppression continues after the first repetition. Further, we found greater activation for warning messages compared to neutral images in the anterior insula, pre-supplemental motor area, and inferior frontal gyrus, suggesting differential processing of security warning messages. However, the repetition suppression effect was similar in these regions for both warning messages and neutral images. Additionally, we observed an increase of activation in the default mode network with repeated exposures, suggestive of increased mind wandering with continuing habituation.

The moderating role of sensory processing sensitivity in the link between stress and depression: A VBM study

This study examined whether components of sensory processing sensitivity (SPS) could moderate the effect of perceived stress on depressive symptoms and its neural substrates. In this study, 244 participants (181females) reported on their SPS, perceived stress, and experienced depressive symptoms, and subsequently underwent a resting-state functional magnetic resonance imaging (RS-fMRI) to explore the neural basis of their SPS characteristics. Behavioral results showed that, compared with individuals low in EOE (i.e., ease of excitation, a sub-dimension of SPS), those high in EOE were more likely to report depressive symptoms under stress. The VBM analysis indicated that EOE was significantly positively correlated with gray matter (GM) volumes of right cerebellum and negatively correlated with GM volumes of right dorsal anterior cingulate cortex (right dACC). Moreover, GM volumes of the two areas moderated the relation between stress and depression. These findings collectively suggest that the structural abnormalities in these regions might account for simulating and experiencing intense emotional reactions frequently among individuals with high EOE. Thus, the accumulation of these negative emotions in reaction to stress may lead to higher probabilities of experiencing depressive symptoms. Taken together, present study shed light on how stress interacted with sensory processing sensitivity to predict depression from the neural perspective.

Does Threat Enlarge Nociceptive Reflex Receptive Fields?

Threat-induced pain modulation can increase survival by amplifying physiological and behavioral reactions toward danger. Threat can also modulate spinal nociception, suggesting engagement of endogenous top-down circuitry. A unique method to assess spinal nociception is via reflex receptive fields (RRF) associated with the nociceptive withdrawal reflex (NWR, a protective spinally-mediated reflex). The size of nociceptive RRFs can be modulated by top-down circuitry with the enlargement of RRFs related to increased spinal nociception. Threat has been previously shown to enhance pain and spinal nociception, but the relationship between threat and RRFs has not been investigated. The present study investigated this issue in 25 healthy individuals. RRFs were determined from NWRs measured by electromyography of the tibialis anterior following electrocutaneous stimulations. RRFs and pain were assessed during periods in which participants were under threat of unpredictable painful abdominal stimulations and when they were not under threat. Results indicated that threat periods led to significantly higher pain, larger nociceptive RRFs and NWR magnitudes. These findings imply that threat produces changes in protective reflexes related to spinal nociceptive sensitivity and increased pain perception. This is likely mediated by top-down circuitry that enhances dorsal horn nociceptive neurons by enlarging RRFs and amplifying ascending pain signals. PERSPECTIVE: This article presents the enlargement of RRF during periods of threat. The results from this study may help clarify the mechanism underlining emotional modulation of spinal nociception.

Suppression durations for facial expressions under breaking continuous flash suppression: effects of faces' low-level image properties

Perceptual biases for fearful facial expressions are observed across many studies. According to the low-level, visual-based account of these biases, fear expressions are advantaged in some way due to their image properties, such as low spatial frequency content. However, there is a degree of empirical disagreement regarding the range of spatial frequency information responsible for perceptual biases. Breaking continuous flash suppression (b. CFS) has explored these effects, showing similar biases for detecting fearful facial expressions. Recent findings from a b. CFS study highlight the role of high, rather than low spatial frequency content in determining faces' visibility. The present study contributes to ongoing discussions regarding the efficacy of b. CFS, and shows that the visibility of facial expressions vary according to how they are normalised for physical contrast and spatially filtered. Findings show that physical contrast normalisation facilitates fear's detectability under b. CFS more than when normalised for apparent contrast, and that this effect is most pronounced when faces are high frequency filtered. Moreover, normalising faces' perceived contrast does not guarantee equality between expressions' visibility under b. CFS. Findings have important implications for the use of contrast normalisation, particularly regarding the extent to which contrast normalisation facilitates fear bias effects.

Evaluating the Association of High Trait Anxiety With a Bias in Familiarity-Based Recognition of Emotional Stimuli

Abstract. In the past decades the role of cognitive biases as maintaining factors of anxiety has been widely researched. This theoretical framework assumes that vulnerability self-referential thoughts promote a hyper-vigilant mode of processing environmental stimuli. In this mode, threatening information increases attentional capture and therefore encoding and retrieval of such stimuli is enhanced. Although this attentional bias has been confirmed, the evidence concerning the memory bias is contradictory. Our hypothesis is that the bias in memory is expressed through the pattern of recognition. Particularly, the aim of this study was to evaluate the association of anxiety with familiarity, a deficient form of recognition which consists only in the identification of the item without retrieval of contextual information. Two groups of 17 participants with low and high anxiety levels performed an experimental task of visual recognition memory, using neutral, positive, and negative pictures. The experiment had two test phases, with a 24-hour interval, to evaluate possible effects of consolidation. The pattern of recognition was measured, behaviorally (through an independent Remember/Know paradigm) and through event-related potentials (ERP). Participants with higher levels of anxiety developed a bias in recognition of arousing stimuli (positive and negative) compared with the control group. This bias was observed behaviorally through an increase of familiarity-based recognition, and was associated with a positive modulation of a right parietal late positive component (LPC) at approximately 600 ms of latency. Participants with higher levels of anxiety are capable of recognizing arousing stimuli but lack efficiency in retrieving past contextual information compared to lower level anxiety participants. A recognition bias can be the first step in cognitive distortions that generate anxiety. This is, to our knowledge, the first study to explore the association of anxiety with familiarity-based recognition, using an independent Remember/Know paradigm combined with electrophysiological data. Further studies with bigger samples and more recording channels are needed to confirm the electrophysiological findings.

The feasibility of an augment reality system to study the psychophysiological correlates of fear-related responses

BACKGROUND

Previous studies have successfully used augmented reality (AR) as an aid to exposure-based treatments for anxiety disorders. However, to the best of our knowledge, none of these studies have measured the physiological correlates of the fear response, relying solely on self-reports and behavioral avoidance tests.

METHODS

As the physiological defensive reactivity pattern impacts on the treatment effectiveness, we tested the feasibility of an AR system integrated in a mobile and wearable device for assessing the psychophysiological mechanisms (heart rate) involved in fear responses in real-life contexts. Specific phobia was used as a model given its prototypical defensive hyperreactivity toward the feared stimulus (spiders to spider phobics, in the current study).

RESULTS

The results showed that the stimuli presented using AR were able to induce physiological alterations in the participants, which were specific depending on the stimulus type (fear or neutral) and on the participants' level of spider fear (phobic and control group). These physiological correlates of the fear response were reflected both in the intensity of heart rate (in relation to the baseline) and in the time needed to react and recover after the stimulus exposure. Finally, we tested a theoretical model that showed that the physiological responses of phobic individuals when facing their phobic stimulus only explained its own data.

CONCLUSIONS

We argue in favor of the system's feasibility at capturing and quantifying the physiological dimension of fear-related responses, which may be of great value for diagnostic and treatment purposes in anxiety disorders, namely specific phobia.

The cerebellum in fear and anxiety-related disorders

Fear and anxiety-related disorders are highly prevalent psychiatric conditions characterized by avoidant and fearful reactions towards specific stimuli or situations, which are disproportionate given the real threat such stimuli entail. These conditions comprise the most common mental disorder group. There are a high proportion of patients who fail to achieve remission and the presence of high relapse rates indicate the therapeutic options available are far from being fully efficient. Despite an increased understanding the neural circuits underlying fear and anxiety-related behaviors in the last decades, a factor that could be partially contributing to the lack of adequate therapies may be an insufficient understanding of the core features of the disorders and their associated neurobiology. Interestingly, the cerebellum shows connections with fear and anxiety-related brain areas and functional involvement in such processes, but explanations for its role in anxiety disorders are lacking. Therefore, the aims of this review are to provide an overview of the neural circuitry of fear and anxiety and its connections to the cerebellum, and of the animal studies that directly assess an involvement of the cerebellum in these processes. Then, the studies performed in patients suffering from anxiety disorders that explore the cerebellum will be discussed. Finally, we'll propose a function for the cerebellum in these disorders, which could guide future experimental approaches to the topic and lead to a better understanding of the neurobiology of anxiety-related disorders, ultimately helping to develop more effective treatments for these conditions.

Heart rate variability response to affective pictures processed in and outside of conscious awareness: Three consecutive studies on emotional regulation

Previous research has increased understanding of the neurobiological basis of emotional regulation. However, less is known concerning the unconscious processing of affective information. Three experiments were performed to investigate the extent to which complex affective stimuli can be processed outside of consciousness and demonstrate possible mechanisms for regulation of resulting emotional responses. In Experiment 1, participants were either instructed to passively observe blocked-picture cues (neutral and negative) or to downregulate their emotions by distancing. Resulting emotional regulation activity was assessed with 0.1-Hz heart rate variability (HRV) indices. In Experiment 2, participants were presented with affective pictures that were rendered consciously invisible by means of continuous flash suppression (CFS). In Experiment 3, two equivalent sets of negative affective pictures were covertly presented and the effect of a cognitive task on emotional regulation was evaluated. Our findings revealed that 0.1-Hz HRV indices exhibited greater change over baseline in response to negative compared to neutral stimuli for both presentation conditions (consciously perceived or not). The implementation of distancing and the cognitive task were both associated with higher 0.1-Hz HRV change scores. These results indicate that even complex affective stimuli can be processed without awareness, resulting in a congruent emotional response that is physiologically detectable. Cognitive strategies can help more effectively regulate this response, implying that conscious perception of a triggering stimulus may not be essential for cognitive regulation.

Prime visibility moderates implicit anger and sadness effects on effort-related cardiac response

Based on the Implicit-Affect-Primes-Effort (IAPE) model (Gendolla, 2012, 2015), an experiment investigated the effect of affect primes' visibility on effort mobilization during cognitive processing. Participants worked on a short-term memory task with integrated sadness vs. anger primes that were presented suboptimally (briefly and masked) vs. optimally (long and visible). Effort was assessed as cardiovascular response, especially cardiac pre-ejection period (PEP). To monitor performance, we assessed response accuracy and reaction times. In accordance with the IAPE model, PEP reactivity was stronger in the sadness-prime condition than in the anger-prime condition-but only when the primes were suboptimally presented. Effects on response accuracy revealed a corresponding pattern. The results suggest that prime visibility is a boundary condition of anger and sadness primes' effect on effort mobilization.

What Is Minimally Required to Elicit Placebo Effects?

Placebo effects have often been attributed to cognitive processes described as "learning" and/or "expectancy," yet the role of conscious awareness is unclear. Furthermore, little is known about the placebo effects in patients with limited cognitive abilities, such as intellectual disability. Here, recent data on placebo mechanisms in patients with impaired cognitive function will be discussed, as well as experimental studies investigating how implicit cognitive processes may shape placebo effects. Together these studies comment on the minimum requirements in order to elicit placebo effects, both from the view of conscious awareness and from the perspective of Intelligence Quotient and basic brain function. Together with recent conceptualizations of placebo effects in terms of predictive coding, there is evidence to suggest that placebo effects are fundamental responses of the brain that have developed to promote survival.

Pharmacological intervention and abstinence in smokers undergoing cessation treatment: A psychophysiological study

As a composite concept, negative affect comprises various aversive emotional experiences, such as irritability and nervousness. It is a critical motivational factor that helps maintain smoking behavior, and contributes significantly to smoking cessation failure as a core withdrawal symptom. Prior research has indicated an important role of nicotinic mechanisms in negative affect processing. The most effective smoking cessation medication, varenicline, targets nicotinic acetylcholine receptors (nAChRs) as a partial agonist, while another first-line cessation medication, bupropion, has shown antagonistic effects on nAChRs. Therefore, it is possible that both medications work to reduce smoking behavior through modulating negative affect processing. To evaluate this hypothesis, we examined the impact of varenicline tartrate and bupropion hydrochloride sustained-release on electrophysiological responses to affective, cigarette-related, and neutral cues before and during smoking cessation treatment in a randomized placebo-controlled clinical trial. The participants were 206 smokers, a subset of 294 participants that were enrolled in a larger smoking cessation clinical trial who were randomly assigned to one medication group for 12weeks. Orbicularis oculi (startle eyeblink response) and corrugator supercilii facial electromyographic (EMG) reactivity toward emotional pictures (i.e., pleasant and unpleasant) in a picture-viewing task were measured before treatment and 2 and 6weeks after treatment was started. The startle and corrugator EMG activities increase with the exposure to unpleasant cues, and served as indices for negative emotional reactivity (NER). We found that after 6weeks, drug reduced startle-related NER in the varenicline group, but not in the bupropion or placebo group. Independent of medication treatment, lower baseline NER, as measured by the corrugator EMG activity, predicted a higher likelihood of smoking abstinence 1 and 3months after quitting smoking. These findings indicate the important roles of varenicline in negative affect processing and negative emotional reactivity in the course of smoking cessation.

Masking exposure to phobic stimuli reduces fear without inducing electrodermal activity

A series of experiments has shown that limiting awareness of exposure to feared stimuli through visual masking-or very brief exposure (VBE)-reduces avoidance of a live tarantula by spider-phobic participants. We investigated this process of fear reduction by directly relating the effects of VBE on electrodermal activity to its ensuing effects on phobic behavior. Sixty spider-phobic participants, identified by approaching a live tarantula and a questionnaire, were administered either VBE to masked spiders or control exposure to masked flowers. Skin conductance levels (SCLs) were continuously recorded during exposure. The participants approached the tarantula again immediately thereafter. VBE reduced avoidance of the tarantula and did not increase SCLs or cause subjective distress relative to control exposure. SCL increases during VBE were strongly negatively correlated with the reduction of self-reported fear of the tarantula: the less that SCLs increased during VBE, the more it reduced fear. VBE only increased SCLs in participants whose fear was not reduced; it did not increase SCLs in participants whose fear of the tarantula was reduced. Awareness of the stimuli did not mediate these effects. Control exposure did not yield any of these effects. In a second experiment, clearly visible exposure to spider images increased SCLs and subjective distress more than both VBE and control exposure, whereas VBE did not increase SCLs or subjective distress relative to control exposure within the same spider-phobic participants. These findings suggest that exposure to phobic images can reduce fear even when it bypasses the induction of electrodermal activity.

Basic Emotions in Human Neuroscience: Neuroimaging and Beyond

The existence of so-called ‘basic emotions’ and their defining attributes represents a long lasting and yet unsettled issue in psychology. Recently, neuroimaging evidence, especially related to the advent of neuroimaging meta-analytic methods, has revitalized this debate in the endeavor of systems and human neuroscience. The core theme focuses on the existence of unique neural bases that are specific and characteristic for each instance of basic emotion. Here we review this evidence, outlining contradictory findings, strengths and limits of different approaches. Constructionism dismisses the existence of dedicated neural structures for basic emotions, considering that the assumption of a one-to-one relationship between neural structures and their functions is central to basic emotion theories. While these critiques are useful to pinpoint current limitations of basic emotions theories, we argue that they do not always appear equally generative in fostering new testable accounts on how the brain relates to affective functions. We then consider evidence beyond PET and fMRI, including results concerning the relation between basic emotions and awareness and data from neuropsychology on patients with focal brain damage. Evidence from lesion studies are indeed particularly informative, as they are able to bring correlational evidence typical of neuroimaging studies to causation, thereby characterizing which brain structures are necessary for, rather than simply related to, basic emotion processing. These other studies shed light on attributes often ascribed to basic emotions, such as automaticity of perception, quick onset, and brief duration. Overall, we consider that evidence in favor of the neurobiological underpinnings of basic emotions outweighs dismissive approaches. In fact, the concept of basic emotions can still be fruitful, if updated to current neurobiological knowledge that overcomes traditional one-to-one localization of functions in the brain. In particular, we propose that the structure-function relationship between brain and emotions is better described in terms of pluripotentiality, which refers to the fact that one neural structure can fulfill multiple functions, depending on the functional network and pattern of co-activations displayed at any given moment.

Quantitative representations of an exaggerated anxiety response in the brain of female spider phobics-a parametric fMRI study

We employed a novel parametric spider picture set in the context of a parametric fMRI anxiety provocation study, designed to tease apart brain regions involved in threat monitoring from regions representing an exaggerated anxiety response in spider phobics. For the stimulus set, we systematically manipulated perceived proximity of threat by varying a depicted spider's context, size, and posture. All stimuli were validated in a behavioral rating study (phobics n = 20; controls n = 20; all female). An independent group participated in a subsequent fMRI anxiety provocation study (phobics n = 7; controls n = 7; all female), in which we compared a whole-brain categorical to a whole-brain parametric analysis. Results demonstrated that the parametric analysis provided a richer characterization of the functional role of the involved brain networks. In three brain regions-the mid insula, the dorsal anterior cingulate, and the ventrolateral prefrontal cortex-activation was linearly modulated by perceived proximity specifically in the spider phobia group, indicating a quantitative representation of an exaggerated anxiety response. In other regions (e.g., the amygdala), activation was linearly modulated in both groups, suggesting a functional role in threat monitoring. Prefrontal regions, such as dorsolateral prefrontal cortex, were activated during anxiety provocation but did not show a stimulus-dependent linear modulation in either group. The results confirm that brain regions involved in anxiety processing hold a quantitative representation of a pathological anxiety response and more generally suggest that parametric fMRI designs may be a very powerful tool for clinical research in the future, particularly when developing novel brain-based interventions (e.g., neurofeedback training). Hum Brain Mapp 38:3025-3038, 2017. © 2017 Wiley Periodicals, Inc.

Fast Detector/First Responder: Interactions between the Superior Colliculus-Pulvinar Pathway and Stimuli Relevant to Primates

Primates are distinguished from other mammals by their heavy reliance on the visual sense, which occurred as a result of natural selection continually favoring those individuals whose visual systems were more responsive to challenges in the natural world. Here we describe two independent but also interrelated visual systems, one cortical and the other subcortical, both of which have been modified and expanded in primates for different functions. Available evidence suggests that while the cortical visual system mainly functions to give primates the ability to assess and adjust to fluid social and ecological environments, the subcortical visual system appears to function as a rapid detector and first responder when time is of the essence, i.e., when survival requires very quick action. We focus here on the subcortical visual system with a review of behavioral and neurophysiological evidence that demonstrates its sensitivity to particular, often emotionally charged, ecological and social stimuli, i.e., snakes and fearful and aggressive facial expressions in conspecifics. We also review the literature on subcortical involvement during another, less emotional, situation that requires rapid detection and response-visually guided reaching and grasping during locomotion-to further emphasize our argument that the subcortical visual system evolved as a rapid detector/first responder, a function that remains in place today. Finally, we argue that investigating deficits in this subcortical system may provide greater understanding of Parkinson's disease and Autism Spectrum disorders (ASD).

Less is more: Neural activity during very brief and clearly visible exposure to phobic stimuli

Research on automatic processes in fear has emphasized the provocation of fear responses rather than their attenuation. We have previously shown that the repeated presentation of feared images without conscious awareness via backward masking reduces avoidance of a live tarantula in spider-phobic participants. Herein we investigated the neural basis for these adaptive effects of masked exposure. 21 spider-phobic and 21 control participants, identified by a psychiatric interview, fear questionnaire, and approaching a live tarantula, viewed stimuli in each of three conditions: (1) very brief exposure (VBE) to masked images of spiders, severely limited awareness; (2) clearly visible exposure (CVE) to spiders, full awareness; and (3) masked images of flowers (control), severely limited awareness. Only VBE to masked spiders generated neural activity more strongly in phobic than in control participants, within subcortical fear, attention, higher-order language, and vision systems. Moreover, VBE activated regions that support fear processing in phobic participants without causing them to experience fear consciously. Counter-intuitively, CVE to the same spiders generated stronger neural activity in control rather than phobic participants within these and other systems. CVE deactivated regions supporting fear regulation and caused phobic participants to experience fear. CVE-induced activations also correlated with measures of explicit fear ratings, whereas VBE-induced activations correlated with measures of implicit fear (color-naming interference of spider words). These multiple dissociations between the effects of VBE and CVE to spiders suggest that limiting awareness of exposure to phobic stimuli through visual masking paradoxically facilitates their processing, while simultaneously minimizing the experience of fear. Hum Brain Mapp 38:2466-2481, 2017. © 2017 Wiley Periodicals, Inc.

Activation of the DLPFC Reveals an Asymmetric Effect in Risky Decision Making: Evidence from a tDCS Study

The phenomenon of loss aversion (the tendency for losses to have a greater impact than comparable gains) has long been observed in daily life. Neurocognitive studies and brain imaging studies have shed light on the correlation between the phenomenon of loss aversion and the brain region of the prefrontal cortex. Recent brain stimulation studies using bilateral transcranial magnetic stimulation or transcranial direct current stimulation (tDCS) have obtained various results showing the causal relationship between brain regions and decision making. With the goal of studying whether unilateral stimulation can change participants’ risky decision making in the frames of gains and losses, we applied different polarities of tDCS over the regions of the right or left prefrontal cortex. We also designed a risk measurement table (Multiple Price List) to reflect the participants’ attitudes toward risky decision making via the crossover point including the frames of gains and losses. The results of our experiment indicated that the participants tended to be more risk averse in the gain frame after receiving left anodal tDCS and more risk seeking in the loss frame after receiving right cathodal tDCS, which was consistent with the hypothesis that the process of risky decision making was correlated with the interaction of multiple systems in the brain. Our conclusion revealed an asymmetric effect of right/left DLPFC when the participants faced gains and losses, which partially provided the neural evidence and a feasible paradigm to help better understand risky decision making and loss aversion. The current study can not only expand the traditional understanding of the behavioral preferences of humans in economics but also accommodate empirical observations of behavioral economists on the preferences of humans.

Amygdala Response to Emotional Stimuli without Awareness: Facts and Interpretations

Over the past two decades, evidence has accumulated that the human amygdala exerts some of its functions also when the observer is not aware of the content, or even presence, of the triggering emotional stimulus. Nevertheless, there is as of yet no consensus on the limits and conditions that affect the extent of amygdala’s response without focused attention or awareness. Here we review past and recent studies on this subject, examining neuroimaging literature on healthy participants as well as brain-damaged patients, and we comment on their strengths and limits. We propose a theoretical distinction between processes involved in attentional unawareness, wherein the stimulus is potentially accessible to enter visual awareness but fails to do so because attention is diverted, and in sensory unawareness, wherein the stimulus fails to enter awareness because its normal processing in the visual cortex is suppressed. We argue this distinction, along with data sampling amygdala responses with high temporal resolution, helps to appreciate the multiplicity of functional and anatomical mechanisms centered on the amygdala and supporting its role in non-conscious emotion processing. Separate, but interacting, networks relay visual information to the amygdala exploiting different computational properties of subcortical and cortical routes, thereby supporting amygdala functions at different stages of emotion processing. This view reconciles some apparent contradictions in the literature, as well as seemingly contrasting proposals, such as the dual stage and the dual route model. We conclude that evidence in favor of the amygdala response without awareness is solid, albeit this response originates from different functional mechanisms and is driven by more complex neural networks than commonly assumed. Acknowledging the complexity of such mechanisms can foster new insights on the varieties of amygdala functions without awareness and their impact on human behavior.

Initial and sustained brain responses to threat anticipation in blood-injection-injury phobia

Blood-injection-injury (BII) phobia differs from other subtypes of specific phobia in that it is associated with elevated disgust-sensitivity as well as specific autonomic and brain responses during processing of phobia-relevant stimuli. To what extent these features play a role already during threat anticipation is unclear. In the current fMRI experiment, 16 female BII phobics and 16 female healthy controls anticipated the presentation of phobia-specific and neutral pictures. On the behavioral level, anxiety dominated the anticipatory period in BII phobics relative to controls, while both anxiety and disgust were elevated during picture presentation. By applying two different models for the analysis of brain responses to anticipation of phobia-specific versus neutral stimuli, we found initial and sustained increases of activation in anterior cingulate cortex (ACC), insula, lateral and medial prefrontal cortex (PFC), thalamus and visual areas, as well as initial activation in the amygdala for BII phobics as compared to healthy controls. These results suggest that BII phobia is characterized by activation of a typical neural defense network during threat anticipation, with anxiety as the predominant emotion.

Unconscious Processing of Negative Animals and Objects: Role of the Amygdala Revealed by fMRI

Previous studies have shown that emotional stimuli can be processed through the amygdala without conscious awareness. The amygdala is also involved in processing animate and social information. However, it is unclear whether different categories of pictures (e.g., animals, objects) elicit different activity in the amygdale and other regions without conscious awareness. The objective of this study was to explore whether the factors of category, emotion and picture context modulate brain activation for unconscious processing. Pictures denoting different nonhuman animals and objects in negative and neutral emotional valences were presented using a sandwich-masking paradigm. Half of them were presented with human-related information in the contexts, and half were not. Our results showed significant interaction among category, emotion and context in the amygdala and subcortical regions. Specifically, negative animals elicited stronger activation in these regions than negative objects, especially with human contexts. In addition, there were different correlation patterns between the amygdala and cortical regions according to whether they included human context. There were limited activations in cortical category-related networks. These results suggest that the amygdala and subcortical regions dominantly process negative animals, and contextual information modulates their activities, making threatening stimuli that are most relevant to human survival preferentially processed without conscious awareness.

Brain Activation Associated with Automatic Processing of Alcohol-Related Cues in Young Heavy Drinkers and Its Modulation by Alcohol Administration

BACKGROUND

While the automatic processing of alcohol-related cues by alcohol abusers is well established in experimental psychopathology approaches, the cerebral regions involved in this phenomenon and the influence of alcohol intake on this process remain unknown. The aim of this functional magnetic resonance imaging (fMRI) study was to investigate the neural mechanisms underlying the processing of task-irrelevant alcohol-related stimuli in young heavy drinkers and their modulation by alcohol administration.

METHODS

Twelve heavy drinking male participants were scanned on 2 separate days; once after a low dose of alcohol intake (0.4 g/kg), and once after a placebo intake, in balanced order. Images of alcoholic drinks, soft drinks, or neutral objects were shown while participants' neural activity was recorded through fMRI. Moreover, participants' attentional focus was manipulated using a task which required them to process the central images of interest (focus alcohol condition) or a center unattended task (focus not on alcohol condition).

RESULTS

Results indicated that an explicit judgment on beverage-related cues increased activation in the prefrontal area compared with the judgment of neutral objects. By comparison with that of task-irrelevant neutral cues, the processing of task-irrelevant alcohol-related cues increased the activation in a large network of cerebral areas including visual and temporal regions, the bilateral anterior cingulate cortex, the posterior cingulate cortex, and the putamen. Moreover, in the condition with focus not on alcohol, the ventral tegmental area (VTA) was particularly activated by the presentation of (task-irrelevant) alcohol-related cues compared to task-irrelevant soft-drink-related cues.

CONCLUSIONS

The VTA was especially involved in the automatic processing of alcohol-related cues in young heavy drinkers. Low dose of alcohol did not modulate the neural substrates involved in the processing of salient alcohol-related cues.

A multi-pathway hypothesis for human visual fear signaling

A hypothesis is proposed for five visual fear signaling pathways in humans, based on an analysis of anatomical connectivity from primate studies and human functional connectvity and tractography from brain imaging studies. Earlier work has identified possible subcortical and cortical fear pathways known as the "low road" and "high road," which arrive at the amygdala independently. In addition to a subcortical pathway, we propose four cortical signaling pathways in humans along the visual ventral stream. All four of these traverse through the LGN to the visual cortex (VC) and branching off at the inferior temporal area, with one projection directly to the amygdala; another traversing the orbitofrontal cortex; and two others passing through the parietal and then prefrontal cortex, one excitatory pathway via the ventral-medial area and one regulatory pathway via the ventral-lateral area. These pathways have progressively longer propagation latencies and may have progressively evolved with brain development to take advantage of higher-level processing. Using the anatomical path lengths and latency estimates for each of these five pathways, predictions are made for the relative processing times at selective ROIs and arrival at the amygdala, based on the presentation of a fear-relevant visual stimulus. Partial verification of the temporal dynamics of this hypothesis might be accomplished using experimental MEG analysis. Possible experimental protocols are suggested.

fMRI neurofeedback facilitates anxiety regulation in females with spider phobia

Background: Spider phobics show an exaggerated fear response when encountering spiders. This fear response is aggravated by negative and irrational beliefs about the feared object. Cognitive reappraisal can target these beliefs, and therefore has a fear regulating effect. The presented study investigated if neurofeedback derived from functional magnetic resonance imaging (fMRI) would facilitate anxiety regulation by cognitive reappraisal, using spider phobia as a model of anxiety disorders. Feedback was provided based on activation in left dorsolateral prefrontal cortex and right insula, as indicators of engagement and regulation success, respectively.

Methods: Eighteen female spider phobics participated in a randomized, controlled, single-blinded study. All participants completed a training session in the MRI scanner. Participants assigned to the neurofeedback condition were instructed to shape their regulatory strategy based on the provided feedback. Participants assigned to the control condition were asked to adapt their strategy intuitively.

Results: Neurofeedback participants exhibited lower anxiety levels than the control group at the end of the training. In addition, only neurofeedback participants achieved down-regulation of insula activation levels by cognitive reappraisal. Group differences became more pronounced over time, supporting learning as a mechanism behind this effect. Importantly, within the neurofeedback group, achieved changes in insula activation levels during training predicted long-term anxiety reduction.

Conclusions: The conducted study provides first evidence that fMRI neurofeedback has a facilitating effect on anxiety regulation in spider phobia.

Classical conditioning of analgesic and hyperalgesic pain responses without conscious awareness

Pain reduction and enhancement can be produced by means of conditioning procedures, yet the role of awareness during the acquisition stage of classical conditioning is unknown. We used psychophysical measures to establish whether conditioned analgesic and hyperalgesic responses could be acquired by unseen (subliminally presented) stimuli. A 2 × 2 factorial design, including subliminal/supraliminal exposures of conditioning stimuli (CS) during acquisition/extinction, was used. Results showed significant analgesic and hyperalgesic responses (P < 0.001), and responses were independent of CS awareness, as subliminal/supraliminal cues during acquisition/extinction led to comparable outcomes. The effect was significantly larger for hyperalgesic than analgesic responses (P < 0.001). Results demonstrate that conscious awareness of the CS is not required during either acquisition or extinction of conditioned analgesia or hyperalgesia. Our results support the notion that nonconscious stimuli have a pervasive effect on human brain function and behavior and may affect learning of complex cognitive processes such as psychologically mediated analgesic and hyperalgesic responses.

Spiders do not evoke greater early posterior negativity in the event-related potential as snakes

It has been long believed that both snakes and spiders are archetypal fear stimuli for humans. Furthermore, snakes have been assumed as stronger threat cues for nonhuman primates. However, it is still unclear whether spiders hold a special status in human perception. The current study explored to what extent spider pictures draw early visual attention [as assessed with early posterior negativity (EPN)] when compared with insects similar to spiders. To measure the EPN, participants watched a random rapid serial presentation of pictures, which consisted of two conditions: spider condition (spider, wasp, bumblebee, beetle) and snake condition (snake, bird). EPN amplitudes revealed no significant difference between spider, wasp, bumblebee, and beetle pictures, whereas EPN amplitudes were significantly larger for snake pictures relative to bird pictures. In addition, EPN amplitudes were significantly larger for snake pictures relative to spider pictures. These results suggest that the early visual attentional capture of animate objects is stronger for snakes, whereas spiders do not appear to hold special early attentional value.

Delaying in vivo exposure to a tarantula with very brief exposure to phobic stimuli

BACKGROUND AND OBJECTIVES

Research has documented the very brief exposure (VBE) effect: the reduction of phobic fear by continuous presentation of masked phobic pictures. In prior studies, phobic participants approached a live tarantula immediately after the masked stimuli were presented. This study tested the hypothesis that VBE would reduce phobic avoidance of the tarantula 24 h later.

METHOD

86 spider-phobic participants were identified with a fear questionnaire and Behavioral Avoidance Test (BAT) with a live tarantula indicative of a DSM-IV diagnosis of Specific Phobia. One week later, they were randomly assigned in double-blind fashion to presentation of a continuous series of 25 trials of masked images of either spiders or flowers (33-ms each), i.e., to VBE or control exposure. The participants gave subjective distress ratings just before and after these exposures. Then they engaged in the BAT again either immediately thereafter or 24 h later to measure changes in avoidance of the tarantula.

RESULTS

Masked images of spiders reduced avoidance of the tarantula both immediately after exposure and 24 h later without causing subjective distress. The effect sizes at these two time points did not significantly differ from each other.

LIMITATIONS

We did not manipulate awareness of the spider images by presenting them unmasked to a third group. Conclusions about the effect of awareness of the stimuli cannot be drawn.

CONCLUSIONS

VBE induces a process of fear reduction before phobic individuals engage in in vivo exposure, which is more distressing. Thus, VBE may help phobic-resistant individuals start treatment more gradually.

Lesions of either anterior orbitofrontal cortex or ventrolateral prefrontal cortex in marmoset monkeys heighten innate fear and attenuate active coping behaviors to predator threat

The ventral prefrontal cortex is an integral part of the neural circuitry that is dysregulated in mood and anxiety disorders. However, the contribution of its distinct sub-regions to the regulation of negative emotion are poorly understood. Recently we implicated both the ventrolateral prefrontal cortex (vlPFC) and anterior orbitofrontal cortex (antOFC) in the regulation of conditioned fear and anxiety responses to a social stimulus, i.e., human intruder, in the marmoset monkey. In the present study we extend our investigations to determine the role of these two regions in regulating innate responses and coping strategies to a predator stimulus, i.e., a model snake. Both the vlPFC and antOFC lesioned groups exhibited enhanced anxiety-related responses to the snake in comparison to controls. Both groups also showed a reduction in active coping behavior. These results indicate that the vlPFC and antOFC contribute independently to the regulation of both innate fear and, as previously reported, conditioned fear, and highlight the importance of these regions in producing stimulus-appropriate coping responses. The finding that dysregulation in two distinct prefrontal regions produces the apparently similar behavioral phenotype of heightened negative emotion provides insight into the varied etiology that may underlie this symptom across a wide variety of neuropsychiatric conditions with implications for personalized treatment strategies.

Effects of cognitive-behavioral therapy on brain responses to subliminal and supraliminal threat and their functional significance in specific phobia

BACKGROUND

Neurocircuitry models of anxiety disorders suggest dysregulated mechanisms encompassing both automatic and elaborate threat processing. However, the extent to which these processes might be differentially modified by psychotherapy and the neural basis of such changes are unknown. We examined the effects of cognitive-behavioral therapy (CBT) in patients with anxiety disorder on brain responses to subliminal and supraliminal threat.

METHODS

3-Tesla functional magnetic resonance imaging was used to assess neural responses to disorder-related stimuli, presented during two backward-masking conditions employed to manipulate stimulus awareness. In 28 spider-phobic patients randomly assigned to a therapy group or a waiting-list control group scanning was performed before and after completing CBT or a waiting period. Scanning was performed one time in 16 healthy control subjects. Self-report and behavioral measures were used to relate CBT-mediated brain activation changes with symptom improvement.

RESULTS

Untreated patients demonstrated abnormal hyperactivation in the amygdala, fusiform gyrus, insula, anterior cingulate cortex, and dorsomedial prefrontal cortex. Successful CBT was reflected in an overall downregulation in these fear circuitry structures, especially in the right amygdala and anterior cingulate cortex, with reductions in amygdala responsiveness associated with self-reported symptom improvement. However, subliminal threat induced a pattern of right-lateralized hyperactivation in the amygdala and fusiform gyrus that was subject to intersession habituation across groups without showing significant sensitivity to CBT.

CONCLUSIONS

These results challenge prevailing models that emphasize a role for amygdala automaticity in the maintenance of anxiety. Our results suggest CBT-related changes in neural activation associated with fear responses to consciously perceived threat.

A Neural Mechanism for Nonconscious Activation of Conditioned Placebo and Nocebo Responses

Fundamental aspects of human behavior operate outside of conscious awareness. Yet, theories of conditioned responses in humans, such as placebo and nocebo effects on pain, have a strong emphasis on conscious recognition of contextual cues that trigger the response. Here, we investigated the neural pathways involved in nonconscious activation of conditioned pain responses, using functional magnetic resonance imaging in healthy participants. Nonconscious compared with conscious activation of conditioned placebo analgesia was associated with increased activation of the orbitofrontal cortex, a structure with direct connections to affective brain regions and basic reward processing. During nonconscious nocebo, there was increased activation of the thalamus, amygdala, and hippocampus. In contrast to previous assumptions about conditioning in humans, our results show that conditioned pain responses can be elicited independently of conscious awareness and our results suggest a hierarchical activation of neural pathways for nonconscious and conscious conditioned responses. Demonstrating that the human brain has a nonconscious mechanism for responding to conditioned cues has major implications for the role of associative learning in behavioral medicine and psychiatry. Our results may also open up for novel approaches to translational animal-to-human research since human consciousness and animal cognition is an inherent paradox in all behavioral science.

Brain activity associated with illusory correlations in animal phobia

Anxiety disorder patients were repeatedly found to overestimate the association between disorder-relevant stimuli and aversive outcomes despite random contingencies. Such an illusory correlation (IC) might play an important role in the return of fear after extinction learning; yet, little is known about how this cognitive bias emerges in the brain. In a functional magnetic resonance imaging study, 18 female patients with spider phobia and 18 healthy controls were exposed to pictures of spiders, mushrooms and puppies followed randomly by either a painful electrical shock or nothing. In advance, both patients and healthy controls expected more shocks after spider pictures. Importantly, only patients with spider phobia continued to overestimate this association after the experiment. The strength of this IC was predicted by increased outcome aversiveness ratings and primary sensory motor cortex activity in response to the shock after spider pictures. Moreover, increased activation of the left dorsolateral prefrontal cortex (dlPFC) to spider pictures predicted the IC. These results support the theory that phobia-relevant stimuli amplify unpleasantness and sensory motor representations of aversive stimuli, which in turn may promote their overestimation. Hyper-activity in dlPFC possibly reflects a pre-occupation of executive resources with phobia-relevant stimuli, thus complicating the accurate monitoring of objective contingencies and the unlearning of fear.