Is there a hypersensitive visual alarm system in panic disorder?

Balance Rehabilitation with Peripheral Visual Stimulation in Patients with Panic Disorder and Agoraphobia: An Open-Pilot Intervention Study

Given the involvement of balance system abnormalities in the pathophysiology of panic disorder and agoraphobia (PD-AG), we evaluated initial evidence for feasibility, acceptability, and potential clinical usefulness of 10 sessions of balance rehabilitation with peripheral visual stimulation (BR-PVS) in an open-pilot 5-week intervention study including six outpatients with PD-AG who presented residual agoraphobia after selective serotonin reuptake inhibitor (SSRI) treatment and cognitive-behavioral therapy, dizziness in daily life, and peripheral visual hypersensitivity measured by posturography. Before and after BR-PVS, patients underwent posturography, otovestibular examination (no patients presented peripheral vestibular abnormalities), and panic-agoraphobic symptom and dizziness evaluation with psychometric tools. After BR-PVS, four patients achieved postural control normalization measured by posturography, and one patient exhibited a favorable trend of improvement. Overall, panic-agoraphobic symptoms and dizziness decreased, even though to a lesser extent in one patient who had not completed the rehabilitation sessions. The study presented reasonable levels of feasibility and acceptability. These findings suggest that balance evaluation should be considered in patients with PD-AGO presenting residual agoraphobia and that BR-PVS might be an adjunctive therapeutic option worth being tested in larger randomized controlled studies.

Responses to balance challenges in persons with panic disorder: A pilot study of computerized static and dynamic balance measurements

INTRODUCTION

Several studies have shown an association between panic disorder (PD) and reduced balance abilities, mainly based on functional balance scales. This pilot study aims to demonstrate the feasibility of studying balance abilities of persons with PD (PwPD) using computerized static and, for the first time, dynamic balance measurements in order to characterize balance control strategies employed by PwPD.

METHODS

Twelve PwPD and 11 healthy controls were recruited. PD diagnosis was confirmed using the Diagnostic and Statistical Manual of Mental Disorders, fourth edition (DSM-IV), and the severity of symptoms was evaluated using the Hamilton Anxiety Scale (HAM-A), PD Severity Scales (PDSS), and Panic and Agoraphobia Scale (PAS). Balance was clinically assessed using the Activities-Specific Balance Confidence (ABC) scale and physically by the Mini-Balance Evaluation Systems Test (Mini-BESTest). Dizziness was evaluated using the Dizziness Handicap Inventory (DHI) scale. Postural control was evaluated statically by measuring body sway and dynamically by measuring body responses to rapid unexpected physical perturbations.

RESULTS

PwPD had higher scores on the HAM-A (17.6 ± 10.3 vs. 3.0 ± 2.9; p < .001), PDSS (11.3 ± 5.1 vs. 0; p < .001), and PAS (20.3 ± 8.7 vs. 0; p < .001) questionnaires and lower scores on the balance scales compared to the controls (ABC scale: 156.2 ± 5.9 vs. 160 ± 0.0, p = .016; Mini-BESTest: 29.4 ± 2.1 vs. 31.4 ± 0.9, p = .014; DHI: 5.3 ± 4.4 vs. 0.09 ± 0.3, p < .001). In the static balance tests, PwPD showed a not-significantly smaller ellipse area of center of pressure trajectory (p = .36) and higher body sway velocity (p = .46), whereas in the dynamic balance tests, PwPD had shorter recovery time from physical perturbations in comparison to controls (2.1 ± 1.2s vs. 1.6 ± 0.9 s, p = .018).

CONCLUSION

The computerized balance tests results point to an adoption of a ''postural rigidity'' strategy by the PwPD, that is, reduced dynamic adaptations in the face of postural challenges. This may reflect a nonsecure compensatory behavior. Further research is needed to delineate this strategy.

Rodent Area Prostriata Converges Multimodal Hierarchical Inputs and Projects to the Structures Important for Visuomotor Behaviors

Area prostriata is a limbic structure critical to fast processing of moving stimuli in far peripheral visual field. Neural substrates underlying this function remain to be discovered. Using both retrograde and anterograde tracing methods, the present study reveals that the prostriata in rat and mouse receives inputs from multimodal hierarchical cortical areas such as primary, secondary, and association visual and auditory cortices and subcortical regions such as the anterior and midline thalamic nuclei and claustrum. Surprisingly, the prostriata also receives strong afferents directly from the rostral part of the dorsal lateral geniculate nucleus. This shortcut pathway probably serves as one of the shortest circuits for fast processing of the peripheral vision and unconscious blindsight since it bypasses the primary visual cortex. The outputs of the prostriata mainly target the presubiculum (including postsubiculum), pulvinar, ventral lateral geniculate nucleus, lateral dorsal thalamic nucleus, and zona incerta as well as the pontine and pretectal nuclei, most of which are heavily involved in subcortical visuomotor functions. Taken together, these results suggest that the prostriata is poised to quickly receive and analyze peripheral visual and other related information and timely initiates and modulates adaptive visuomotor behaviors, particularly in response to unexpected quickly looming threats.

Initial white matter connectivity differences between remitters and non-remitters of patients with panic disorder after 6 months of pharmacotherapy

Panic disorder (PD) is a harmful mental condition that causes relapsed and persistent impairment. In the treatment of PD, the prognosis for PD should be considered. However, the relationship between pharmacotherapy and biomarkers, for predicting a better response through neuroimaging, is a little known. The purpose of the present study was to examine whether there would be the initial white matter (WM) regions associated with the remission in 6 months. A total of 104 patients with PD were investigated in the study. After six months, there were 17 remission patients with PD and 81 non-remission patients. The Panic Disorder Severity Scale, Albany Panic and Phobia Questionnaire, Anxiety Sensitivity Inventory-Revised, Beck Anxiety Inventory, and Beck Depression Inventory were assessed for all patients at baseline. We compared the diffusion indices between remission and non-remission group at 6 months using Tract-Based Spatial Statistics. The results showed that the fractional anisotropy (FA) values were significantly higher in the non-remitter group compared with those in the remitter group in the WM regions, such as the posterior corona radiata and superior longitudinal fasciculus, at the 6 month evaluation. The logistic regression analysis with clinical symptom severity and FA values of the WM regions as covariates showed that FA values in those regions and the Beck Depression Inventory-II predicted poor remission. This study suggests that posterior corona radiata and superior longitudinal fasciculus are related to potential predictive factors of 6-month remission in patients with PD. WM regions associated with the long-term remission should be verified with further investigations.

Impact of respiratory protective devices on respiration: Implications for panic vulnerability during the COVID-19 pandemic

BACKGROUND

The wearing of respiratory protective devices (RPDs) correctly and continually in situations where people are at risk of respiratory infections is crucial for infection prevention. Certain people are poorly compliant with RPDs due to RPD-related annoyance, including respiratory discomfort. We hypothesized that individuals vulnerable to panic attacks are included in this group. No published studies on this topic are available. The evidence for our hypothesis was reviewed in this study as a starting point for future research.

METHODS

We selected a set of experimental studies that measured the respiratory physiological burden in RPD wearers through objective and validated methods. We conducted a bibliographic search of publications in the PubMed database (January 2000-May 2020) to identify representative studies that may be of interest for panic respiratory pathophysiology.

RESULTS

Five studies were included. Wearing RPDs exerted significant respiratory effects, including increased breathing resistance, CO₂ rebreathing due to CO₂ accumulation in the RPD cavity, and decreased inhaled O₂ concentration. We discussed the implications of these effects on the respiratory pathophysiology of panic.

LIMITATIONS

Most studies had a small sample size, with a preponderance of young participants. Different methodologies were used across the studies. Furthermore, differences in physical responses between wearing RPDs in experimental settings or daily life cannot be excluded.

CONCLUSIONS

This research supports the idea that panic-prone individuals may be at higher risk of respiratory discomfort when wearing RPDs, thereby reducing their tolerance for these devices. Strategies to decrease discomfort should be identified to overcome the risk of poor compliance.

'The last channel': vision at the temporal margin of the field

The human visual field, on the temporal side, extends to at least 90° from the line of sight. Using a two-alternative forced-choice procedure in which observers are asked to report the direction of motion of a Gabor patch, and taking precautions to exclude unconscious eye movements in the direction of the stimulus, we show that the limiting eccentricity of image-forming vision can be established with precision. There are large, but reliable, individual differences in the limiting eccentricity. The limiting eccentricity exhibits a dependence on log contrast; but it is not reduced when the modulation visible to the rods is attenuated, a result compatible with the histological evidence that the outermost part of the retina exhibits a high density of cones. Our working hypothesis is that only one type of neural channel is present in the far periphery of the retina, a channel that responds to temporally modulated stimuli of low spatial frequency and that is directionally selective.

Functional Head Impulse Test With and Without Optokinetic Stimulation in Subjects With Persistent Postural Perceptual Dizziness (PPPD): Preliminary Report

OBJECTIVE

Persistent postural perceptual dizziness (PPPD) is a clinical condition characterized by unsteadiness present on most days for a period of at least 3 months. The aim of our work was to assess vestibular function, the role of anxiety, and possible interactions between visual and vestibular systems in patients with PPPD.

STUDY DESIGN

Cross-sectional prospective study.

SETTING

Tertiary referral center.

PATIENTS

Twenty-five PPPD patients.

INTERVENTIONS

Clinical history was collected before examination; vestibular function was assessed through bedside examination, video and functional head impulse test (video-HIT, f-HIT). The latter test was based on having the patient identify an optotype displayed on a computer screen during passive head rotations. The test was repeated while optokinetic stimulation (OKS) was given on the screen. Results were compared with those of 25 controls. State and trait anxiety levels were measured with the State-Trait Anxiety Inventory (STAI) questionnaire. Anxiety before and after vestibular examination was assessed using a VAS scale.

MAIN OUTCOME MEASURE

Results of video and functional HIT with and without OKS.

RESULTS

Video-HIT and f-HIT showed normal values in all subjects. f-HIT with OKS provoked more reading errors in patients than in controls. The interaction of group per time detected different decreasing trends between the two groups (p = 0.0002).Patients presented a reduction in anxiety levels after examination. Nine patients fulfilled diagnostic criteria for vestibular migraine, eight of whom presented nystagmus either to positional tests or vibration test. Only anxiety levels before testing were predictive of worsening of f-HIT with optokinetic stimulation (p = 0.0007).

CONCLUSIONS

Our data support the hypothesis that increased anxiety may play a role in visuo-vestibular interactions; moreover, they are not inconsistent with the hypothesis that OKS might provoke a "threatening effect," leading to gaze bias during examination.

Localization of area prostriata and its connections with primary visual cortex in rodent

Area prostriata (Pro) has been found to play important roles in the rapid processing of moving stimuli in the far peripheral visual field. However, the specific neural substrates responsible for these functions remain unknown. In this study, we first examined the location, extent, and topography of the rodent equivalent of the primate Pro based on cytoarchitecture and molecular markers. We then identified its intimate connections with the primary visual cortex (V1) using retrograde and anterograde tracers. Our main finding is that medial V1, which receives peripheral visual information, has strong reciprocal connections with the Pro in both rat and mouse while lateral V1 has significantly fewer such connections. The direct V1 inputs to the Pro provide at least one of the shortest pathways for visual information to reach the Pro, and may be crucial to the fast processing of unexpected stimuli in the peripheral visual field.

Visual Cortex: The Eccentric Area Prostriata in the Human Brain

Human area Prostriata is a small, unstudied portion of the visual brain set deep in the calcarine sulcus, next to V1. A recent neuroimaging study in humans indicates that this area is specialized to respond to rapidly moving stimuli in the far periphery, consistent with single-unit responses in other mammals.

Toward a personalized therapy for panic disorder: preliminary considerations from a work in progress

Although several treatment options for panic disorder (PD) are available, the best intervention for each individual patient remains uncertain and the use of a more personalized therapeutic approach in PD is required. In clinical practice, clinicians combine general scientific information and personal experience in the decision-making process to choose a tailored treatment for each patient. In this sense, clinicians already use a somehow personalized medicine strategy. However, the influence of their interpretative personal models may lead to bias related to personal convictions, not sufficiently grounded on scientific evidence. Hence, an effort to give some advice based on the science of personalized medicine could have positive effects on clinicians' decisions. Based on a narrative review of meta-analyses, systematic reviews, and experimental studies, we proposed a first-step attempt of evidence-based personalized therapy for PD. We focused on some phenomenological profiles, encompassing symptoms during/outside panic attacks, related patterns of physiological functions, and some aspects of physical health, which might be worth considering when developing treatment plans for patients with PD. We considered respiratory, cardiac, vestibular, and derealization/depersonalization profiles, with related implications for treatment. Given the extensiveness of the topic, we considered only medications and some somatic interventions. Our proposal should be considered neither exhaustive nor conclusive, as it is meant as a very preliminary step toward a future, robust evidence-based personalized therapy for PD. Clearly much more work is needed to achieve this goal, and recent technological advances, such as wearable devices, big data platforms, and the application of machine learning techniques, may help obtain reliable findings. We believe that combining the efforts of different research groups in this work in progress can lead to largely shared conclusions in the near future.

Dizziness

Dizziness is a common symptom encountered by all physicians. Dizziness and related symptoms are frequently linked to 1 or more of a list of contributors that includes benign paroxysmal positional vertigo, Ménière disease, migraine, acute peripheral vestibulopathy, cerebral ischemia, and anxiety disorders. Awareness of these common clinical patterns increases the likelihood of making a rapid, accurate diagnosis.

Are there advances in pharmacotherapy for panic disorder? A systematic review of the past five years

INTRODUCTION

Several effective medications are available for treating panic disorder (PD). However, outcomes are unsatisfactory in a number of patients, suggesting the usefulness of expanding the array of antipanic drugs and improving the quality of response to current recommended treatments.

AREAS COVERED

The authors have performed an updated systematic review of pharmacological studies (phase III onwards) to examine whether advances have been made in the last five years. Only four studies were included. D-cycloserine no longer seemed promising as a cognitive-behavioral therapy (CBT) enhancer. Some preliminary findings concerning the optimization of recommended medications deserved consideration, including: the possibility that SSRIs are more effective than CBT alone in treating panic attacks, combined therapy is preferable when agoraphobia is present, and clonazepam is more potent than paroxetine in decreasing panic relapse.

EXPERT OPINION

Given the lack of novel treatments, expanding a personalized approach to the existing medications seems to be the most feasible strategy to improve pharmacotherapy outcomes regarding PD. Recent technological progress, including wearable devices collecting real-time data, 'big data' platforms, and application of machine learning techniques might help make outcome prediction more reliable. Further research on previously promising novel treatments is also recommended.

Both anxiety and joint laxity determine the olfactory features in panic disorder

Previous research showed a high sensitivity in sensorial modalities in panic disorder (PD). This disorder has been consistently associated to the joint hypermobility syndrome (JHS). In non-clinical samples, this collagen alteration has been also related to an enhanced sensitivity in some sensorial modalities. The main aim of this study is to explore the olfactory functioning in PD in relation to JHS. Sixty patients with PD and sixty healthy controls performed the Sniffin' Sticks Test (SST) (threshold subtest), and completed the Affective Impact of Odors scale (AIO), the Relational Scale of Olfaction (EROL), and the Odor Awareness Scale (OAS). Clinical symptom rating scales and JHS assessment were also obtained. PD patients showed enhanced odor acuity, greater reactivity to smells and also increased odor awareness compared to the healthy controls. Within the patients group, those suffering from JHS displayed higher functioning in all olfactory domains compared to the non-JHS ones. The JHS and anxiety measures emerged as predictor variables of the olfactory function. The present findings highlight the importance of the olfactory function in PD and underline that both, JHS and anxiety, determine the olfactory characteristics in this disorder.

Management of Treatment-Resistant Panic Disorder

PURPOSE OF REVIEW

Purpose of Review Management of treatment-resistant (TR) panic disorder (PD) is an unresolved issue. In this paper, we provide a brief summary of previous findings, an updated (2015-2017) systematic review of pharmacological/non-pharmacological studies, and our personal perspective on this topic.

RECENT FINDINGS

Recent Findings We found a very limited number of recent findings. Quetiapine extended-release augmentation has not been found to be beneficial, in comparison to placebo, in non-responders to previously recommended pharmacotherapy. In non-responders to cognitive behavioral therapy (CBT), switching to paroxetine/citalopram has been found to be more effective than continuing CBT. Acceptance and commitment therapy (ACT) has shown some improvement in patients' resistance to previous psychological/pharmacological interventions compared with a waiting-list condition.

SUMMARY

Summary Previous and recent findings regarding the treatment of TR PD suffer from several methodological limitations. Available studies provide insufficient evidence to support the use of medications alternative to the recommended medications; the efficacy of ACT needs confirmation with more rigorous methodology. Prolonged pharmacotherapy may produce significant improvement in patients with unsatisfactory response to short-term pharmacotherapy, while switching to pharmacotherapy may help non-responders to CBT. We discuss our personal perspective on the definition of "treatment resistance" as it relates to PD and provide personalized intervention strategies to increase favorable clinical outcomes based on our clinical expertise and review of experimental studies on the pathophysiology of PD.

White matter correlates of anxiety sensitivity in panic disorder

BACKGROUND

Anxiety sensitivity (AS) refers to a fear of anxiety-related sensations and is a dispositional variable especially elevated in patients with panic disorder (PD). Although several functional imaging studies of AS in patients with PD have suggested the presence of altered neural activity in paralimbic areas such as the insula, no study has investigated white matter (WM) alterations in patients with PD in relation to AS. The objective of this study was to investigate the WM correlates of AS in patients with PD.

METHODS

One-hundred and twelve right-handed patients with PD and 48 healthy control (HC) subjects were enrolled in this study. The Anxiety Sensitivity Inventory-Revised (ASI-R), the Panic Disorder Severity Scale (PDSS), the Albany Panic and Phobia Questionnaire (APPQ), the Beck Anxiety Inventory (BAI), and the Beck Depression Inventory (BDI) were administered. Tract-based spatial statistics were used for diffusion tensor magnetic resonance imaging analysis.

RESULTS

Among the patients with PD, the ASI-R total scores were significantly correlated with the fractional anisotropy values of the WM regions near the insula, the splenium of the corpus callosum, the tapetum, the fornix/stria terminalis, the posterior limb of the internal capsule, the retrolenticular part of the internal capsule, the posterior thalamic radiation, the sagittal striatum, and the posterior corona radiata located in temporo-parieto-limbic regions and are involved in interoceptive processing (p<0.01; threshold-free cluster enhancement [TFCE]-corrected). These WM regions were also significantly correlated with the APPQ interoceptive avoidance subscale and BDI scores in patients with PD (p<0.01, TFCE-corrected). Correlation analysis among the HC subjects revealed no significant findings.

LIMITATIONS

There has been no comparative study on the structural neural correlates of AS in PD.

CONCLUSIONS

The current study suggests that the WM correlates of AS in patients with PD may be associated with the insula and the adjacent temporo-parieto-limbic WM regions, which may play important roles in interoceptive processing in the brain and in depression in PD.

Posturographic destabilization in eating disorders in female patients exposed to body image related phobic stimuli

Human postural control is dependent on the central integration of vestibular, visual and proprioceptive inputs. Psychological states can affect balance control: anxiety, in particular, has been shown to influence balance mediated by visual stimuli. We hypothesized that patients with eating disorders would show postural destabilization when exposed to their image in a mirror and to the image of a fashion model representing their body ideal in comparison to body neutral stimuli. Seventeen females patients attending a day centre for the treatment of eating disorders were administered psychometric measures of body dissatisfaction, anxiety, depression and underwent posturographic measures with their eyes closed, open, watching a neutral stimulus, while exposed to a full length mirror and to an image of a fashion model corresponding to their body image. Results were compared to those obtained by eighteen healthy subjects. Eating disordered patients showed higher levels of body dissatisfaction and higher postural destabilization than controls, but this was limited to the conditions in which they were exposed to their mirror image or a fashion model image. Postural destabilization under these conditions correlated with measures of body dissatisfaction. In eating disordered patients, body related stimuli seem to act as phobic stimuli in the posturographic paradigm used. If confirmed, this has the potential to be developed for diagnostic and therapeutic purposes.

Olfactory functioning in panic disorder

BACKGROUND

The olfactory function in panic disorder (PD) has been scarcely approached in the literature. The purpose of this paper is to study this question by focusing on the olfactory sensitivity (i.e. detection threshold), the reactivity to odors, and the odor awareness in patients suffering from PD.

METHODS

41 patients with PD and 41 healthy controls performed Sniffin׳ Sticks Test (threshold subtest) and completed the Affective Impact of Odors scale (AIO), the Relational Scale of Olfaction (EROL) and the Odor Awareness Scale (OAS). Clinical symptoms rating scales were concurrently obtained.

RESULTS

PD patients showed lower olfactory detection thresholds (i.e. higher sensitivity) along with an enhanced reactivity to odors as well as a greater olfactory awareness compared to the healthy controls. The severity of PD was significantly associated with the olfactory questionnaires ratings, but not with the detection ability. Olfactory measures were intercorrelated in most cases.

LIMITATIONS

i) The results of the olfactory sensitivity are limited to one odorant (phenyl ethyl alcohol) and thus may not be generalizable to other odorants. ii) As comorbid Axis II disorders were not screened, it is not possible to exclude the influence of personality traits in our results. iii) The involvement of the medications in some olfactory outcomes cannot be ruled out.

CONCLUSION

The current findings highlight the importance of the olfactory function in PD as patients appeared to be highly sensitive, reactive and aware of odors. These results are discussed in the light of the common neural substrates involved in the olfactory processing and in the pathophysiology of PD, and also related to the clinical features of this disorder.

The effects of the catechol-O-methyltransferase val158met polymorphism on white matter connectivity in patients with panic disorder

BACKGROUND

The catechol-O-methyltransferase (COMT) gene val158met polymorphism (rs4680) has been found to be associated with various psychiatric phenotypes including panic disorder. Considering the probable genetic influence of COMT on the pathogenesis of panic disorder and white matter connectivity, the present study investigated white matter connectivity using diffusion tensor imaging in relation to the COMT genotype in panic disorder.

METHODS

Twenty-six patients with panic disorder and twenty-six age- and gender-matched healthy controls participated in this study. Brain magnetic resonance scans and genotype analysis for COMT rs4680 were conducted. Panic Disorder Severity Scale, Albany Panic and Phobia Questionnaire, and Anxiety Sensitivity Inventory-Revised were assessed. Tract-based spatial statistics (TBSS) were used for image analysis.

RESULTS

There was no significant difference in white matter analysis between panic disorder and healthy controls. However, TBSS analysis showed increased fractional anisotropy (FA) in posterior thalamic radiation, posterior and superior corona radiata, superior longitudinal fasciculus, and sagittal stratum, all located in the right hemisphere in COMT AA/AG genotype group compared to GG genotype in panic disorder. Voxelwise correlational analysis revealed the symptom severity scores are correlated with the FA in white matter tracts that previously showed significant group differences between AA/AG and GG genotypes in COMT AA/AG genotype group, while no significant correlation was found in GG genotype group.

LIMITATIONS

The sample size in each group was small, hence, further studies with larger numbers of patients are needed to confirm our findings.

CONCLUSIONS

These data suggested that COMT rs4680 could affect the white matter connectivity in panic disorder.

Impaired perceptual processing and conceptual cognition in patients with anxiety disorders: a pilot study with the binocular depth inversion paradigm

The binocular depth inversion test (BDIT) measures a common illusion of visual perception whereby implausible objects are seen as normal, e.g., a hollow face is perceived as a normal, convex face. Such inversion is frequent, especially for objects with a high degree of familiarity. Under normal conditions, cognitive factors apparently override the binocular disparity cues of stereopsis. This internal mechanism of "censorship" of perception, which balances "top-down" and "bottom-up" processes of perception to come to a cognitive coherence, which is congruent to previous experience and concepts, appears to be disturbed in (pro-)psychotic states. The BDIT has been shown to be a sensitive measure of impaired higher visual processing and conceptual cognition common to conditions including schizophrenia, cannabinoid-intoxication, and sleep deprivation but not depression. In this pilot study, we tested the performance of patients with anxiety disorders (ICD-10 F40 and F41) compared to matched controls using the BDIT paradigm. Anxiety patients scored significantly higher on the BDIT than controls, in a range comparable to propsychotic conditions. The findings suggest that anxiety patients could have abnormalities in central perceptual processing, top-down processing (conceptual cognition), and reality testing similar to (pro-)psychotic conditions. Implications of these findings are discussed in relation to therapeutic interventions with anxiety disorders.

A specialized area in limbic cortex for fast analysis of peripheral vision

In primates, prostriata is a small area located between the primary visual cortex (V1) and the hippocampal formation. Prostriata sends connections to multisensory and high-order association areas in the temporal, parietal, cingulate, orbitofrontal, and frontopolar cortices. It is characterized by a relatively simple histological organization, alluding to an early origin in mammalian evolution. Here we show that prostriata neurons in marmoset monkeys exhibit a unique combination of response properties, suggesting a new pathway for rapid distribution of visual information in parallel with the traditionally recognized dorsal and ventral streams. Whereas the location and known connections of prostriata suggest a high-level association area, its response properties are unexpectedly simple, resembling those found in early stages of the visual processing: neurons have robust, nonadapting responses to simple stimuli, with latencies comparable to those found in V1, and are broadly tuned to stimulus orientation and spatiotemporal frequency. However, their receptive fields are enormous and form a unique topographic map that emphasizes the far periphery of the visual field. These results suggest a specialized circuit through which stimuli in peripheral vision can bypass the elaborate hierarchy of extrastriate visual areas and rapidly elicit coordinated motor and cognitive responses across multiple brain systems.

Antianxiety medications for the treatment of complex agoraphobia: pharmacological interventions for a behavioral condition

BACKGROUND

Although there are controversial issues (the "American view" and the "European view") regarding the construct and definition of agoraphobia (AG), this syndrome is well recognized and it is a burden in the lives of millions of people worldwide. To better clarify the role of drug therapy in AG, the authors summarized and discussed recent evidence on pharmacological treatments, based on clinical trials available from 2000, with the aim of highlighting pharmacotherapies that may improve this complex syndrome.

METHODS

A systematic review of the literature regarding the pharmacological treatment of AG was carried out using MEDLINE, EBSCO, and Cochrane databases, with keywords individuated by MeSH research. Only randomized, placebo-controlled studies or comparative clinical trials were included.

RESULTS

After selection, 25 studies were included. All the selected studies included patients with AG associated with panic disorder. Effective compounds included selective serotonin reuptake inhibitors, serotonin-norepinephrine reuptake inhibitors, tricyclic antidepressants, selective noradrenergic reuptake inhibitors, and benzodiazepines. Paroxetine, sertraline, citalopram, escitalopram, and clomipramine showed the most consistent results, while fluvoxamine, fluoxetine, and imipramine showed limited efficacy. Preliminary results suggested the potential efficacy of inositol; D-cycloserine showed mixed results for its ability to improve the outcome of exposure-based cognitive behavioral therapy. More studies with the latter compounds are needed before drawing definitive conclusions.

CONCLUSION

No studies have been specifically oriented toward evaluating the effect of drugs on AG; in the available studies, the improvement of AG might have been the consequence of the reduction of panic attacks. Before developing a "true" psychopharmacology of AG it is crucial to clarify its definition. There may be several potential mechanisms involved, including fear-learning processes, balance system dysfunction, high light sensitivity, and impaired visuospatial abilities, but further studies are warranted.