Motivational context and neurocomputation of stop expectation moderate early attention responses supporting proactive inhibitory control

Alterations in attention to cues signaling the need for inhibitory control play a significant role in a wide range of psychopathology. However, the degree to which motivational and attentional factors shape the neurocomputations of proactive inhibitory control remains poorly understood. The present study investigated how variation in monetary incentive valence and stake modulate the neurocomputational signatures of proactive inhibitory control. Adults (N = 46) completed a Stop-Signal Task (SST) with concurrent EEG recording under four conditions associated with stop performance feedback: low and high punishment (following unsuccessful stops) and low and high reward (following successful stops). A Bayesian learning model was used to infer individual's probabilistic expectations of the need to stop on each trial: P(stop). Linear mixed effects models were used to examine whether interactions between motivational valence, stake, and P(stop) parameters predicted P1 and N1 attention-related event-related potentials (ERPs) time-locked to the go-onset stimulus. We found that P1 amplitudes increased at higher levels of P(stop) in punished but not rewarded conditions, although P1 amplitude differences between punished and rewarded blocks were maximal on trials when the need to inhibit was least expected. N1 amplitudes were positively related to P(stop) in the high punishment condition (low N1 amplitude), but negatively related to P(stop) in the high reward condition (high N1 amplitude). Critically, high P(stop)-related N1 amplitude to the go-stimulus predicted behavioral stop success during the high reward block, providing evidence for the role of motivationally relevant context and inhibitory control expectations in modulating the proactive allocation of attentional resources that affect inhibitory control. These findings provide novel insights into the neurocomputational mechanisms underlying proactive inhibitory control under valence-dependent motivational contexts, setting the stage for developing motivation-based interventions that boost inhibitory control.

Adjunctive cognitive training with exposure enhances fear and neural outcomes in social anxiety

Exposure-based cognitive behavioral therapy (CBT) is the gold standard for treating social anxiety disorder (SAD), yet response is not universal. CBT is thought to operate via extinction-related learning during exposure, which in turn relies on cognitive processes such as working memory. The present proof-of-concept study investigates the potential for training working memory to improve anxiety related outcomes following exposure. Thirty-three adults with elevated social anxiety were randomized to complete a working memory training or sham training condition. Post-training, participants completed a working memory assessment, speech exposure session, and two fMRI tasks. Participants who received working memory training demonstrated lower distress ratings by the end of the speech exposures and better performance on the fMRI working memory task than those in sham. Working memory training completers had greater neural activation in frontoparietal regions during an in-scanner working memory task and exhibited less neural activation in the fusiform gyrus in response to an emotional face processing task than those in sham. Adding working memory training to exposure procedures could strengthen functioning of frontoparietal regions and alter emotional processing - key mechanisms implicated in extinction learning. Findings provide preliminary evidence that training working memory in conjunction with exposure may enhance exposure success.

Resting-state connectivity subtype of comorbid PTSD and alcohol use disorder moderates improvement from integrated prolonged exposure therapy in Veterans

BACKGROUND

Posttraumatic stress disorder (PTSD) and alcohol use disorder (AUD) are highly comorbid and are associated with significant functional impairment and inconsistent treatment outcomes. Data-driven subtyping of this clinically heterogeneous patient population and the associated underlying neural mechanisms are highly needed to identify who will benefit from psychotherapy.

METHODS

In 53 comorbid PTSD/AUD patients, resting-state functional magnetic resonance imaging was collected prior to undergoing individual psychotherapy. We used a data-driven approach to subgroup patients based on directed connectivity profiles. Connectivity subgroups were compared on clinical measures of PTSD severity and heavy alcohol use collected at pre- and post-treatment.

RESULTS

We identified a subgroup of patients associated with improvement in PTSD symptoms from integrated-prolonged exposure therapy. This subgroup was characterized by lower insula to inferior parietal cortex (IPC) connectivity, higher pregenual anterior cingulate cortex (pgACC) to posterior midcingulate cortex connectivity and a unique pgACC to IPC path. We did not observe any connectivity subgroup that uniquely benefited from integrated-coping skills or subgroups associated with change in alcohol consumption.

CONCLUSIONS

Data-driven approaches to characterize PTSD/AUD subtypes have the potential to identify brain network profiles that are implicated in the benefit from psychological interventions - setting the stage for future research that targets these brain circuit communication patterns to boost treatment efficacy.

Pre-deployment threat learning predicts increased risk for post-deployment insomnia: Evidence from the Marine Resiliency Study

Insomnia is a common and impairing consequence of military deployment, but little is known about pre-deployment risk factors for post-deployment insomnia. Abnormal threat learning tendencies are commonly observed in individuals with insomnia and maladaptive responses to stress have been implicated in the development of insomnia, suggesting that threat learning could be an important risk factor for post-deployment insomnia. Here, we examined pre-deployment threat learning as a predictor of post-deployment insomnia and the potential mechanisms underlying this effect. Male servicemembers (N = 814) completed measures of insomnia, psychiatric symptoms, and a threat learning task before and after military deployment. Threat learning indices that differentiated participants with versus withoutinsomnia at post-deployment were tested as pre-deployment predictors of post-deployment insomnia. Post-deployment insomnia was linked to elevations on several threat learning indices at post-deployment, but only higher threat conditioning, as indexed by higher threat expectancy ratings to the danger cue, emerged as a pre-deployment predictor of post-deployment insomnia. This effect was independent of combat exposure levels and partially mediated by greater post-deployment nightmares. The tendency to acquire stronger expectations of aversive events following encounters with danger cues may increase risk for post-deployment insomnia, in part due to the development of more severe nightmares.

Deriving psychiatric symptom-based biomarkers from multivariate relationships between psychophysiological and biochemical measures

Identification of biomarkers for psychiatric disorders remains very challenging due to substantial symptom heterogeneity and diagnostic comorbidity, limiting the ability to map symptoms to underlying neurobiology. Dimensional symptom clusters, such as anhedonia, hyperarousal, etc., are complex and arise due to interactions of a multitude of complex biological relationships. The primary aim of the current investigation was to use multi-set canonical correlation analysis (mCCA) to derive biomarkers (biochemical, physiological) linked to dimensional symptoms across the anxiety and depressive spectrum. Active-duty service members (N = 2,592) completed standardized depression, anxiety and posttraumatic stress questionnaires and several psychophysiological and biochemical assays. Using this approach, we identified two phenotype associations between distinct physiological and biological phenotypes. One was characterized by symptoms of dysphoric arousal (anhedonia, anxiety, hypervigilance) which was associated with low blood pressure and startle reactivity. This finding is in line with previous studies suggesting blunted physiological reactivity is associated with subpopulations endorsing anxiety with comorbid depressive features. A second phenotype of anxious fatigue (high anxiety and reexperiencing/avoidance symptoms coupled with fatigue) was associated with elevated blood levels of norepinephrine and the inflammatory marker C-reactive protein in conjunction with high blood pressure. This second phenotype may describe populations in which inflammation and high sympathetic outflow might contribute to anxious fatigue. Overall, these findings support the growing consensus that distinct neuropsychiatric symptom patterns are associated with differential physiological and blood-based biological profiles and highlight the potential of mCCA to reveal important psychiatric symptom biomarkers from several psychophysiological and biochemical measures.

Working Memory Performance for Differentially Conditioned Stimuli

Previous work suggests that threat-related stimuli are stored to a greater degree in working memory compared to neutral stimuli. However, most of this research has focused on stimuli with physically salient threat attributes (e.g., angry faces), failing to account for how a "neutral" stimulus that has acquired threat-related associations through differential aversive conditioning influences working memory. The current study examined how differentially conditioned safe (i.e., CS-) and threat (i.e., CS+) stimuli are stored in working memory relative to a novel, non-associated (i.e., N) stimuli. Participants (n = 69) completed a differential fear conditioning task followed by a change detection task consisting of three conditions (CS+, CS-, N) across two loads (small, large). Results revealed individuals successfully learned to distinguishing CS+ from CS- conditions during the differential aversive conditioning task. Our working memory outcomes indicated successful load manipulation effects, but no statistically significant differences in accuracy, response time (RT), or Pashler's K measures of working memory capacity between CS+, CS-, or N conditions. However, we observed significantly reduced RT difference scores for the CS+ compared to CS- condition, indicating greater RT differences between the CS+ and N condition vs. the CS- and N condition. These findings suggest that differentially conditioned stimuli have little impact on behavioral outcomes of working memory compared to novel stimuli that had not been associated with previous safe of aversive outcomes, at least in healthy populations.

Anhedonia in Posttraumatic Stress Disorder: Prevalence, Phenotypes, and Neural Circuitry

Anhedonia, the reduction of pleasure and reward-seeking behavior, is a transdiagnostic construct associated with a range of important health outcomes. As with other psychiatric disorders, anhedonia is a relatively common, though understudied, feature of posttraumatic stress disorder (PTSD) that is not adequately targeted by existing treatments. The purpose of this review is to describe the current state of the literature on anhedonia in PTSD and highlight areas for future research based on gaps in the existing evidence base. First, we review evidence for anhedonia symptoms as a distinct PTSD symptom factor and its associations with psychiatric comorbidity, disease trajectory, and quality of life outcomes, as well as describe theories that seek to explain the occurrence of anhedonia among individuals with PTSD. Second, we review evidence for behavioral and neural alterations in reward processing and circuitry, a marker of anhedonia, among individuals with PTSD and in animal models relevant to this disorder. Finally, we discuss key gaps in our understanding of anhedonia in PTSD and suggest areas for future research. Specifically, the timing of anhedonia symptom development and underlying circuit dysfunction in the trauma response trajectory, as well as potential differential associations of facets of anhedonia on clinical outcomes, remain unclear. Additionally, further research is needed to determine potential moderators of anhedonia, as well as the efficacy and effectiveness of psychotherapeutic, psychopharmacological, and device-based interventions targeting anhedonia among individuals with PTSD. A more thorough understanding of these topics will ultimately improve prevention and intervention efforts for PTSD.

Dissociable impact of childhood trauma and deployment trauma on affective modulation of startle

Trauma disorders are often associated with alterations in aversive anticipation and disruptions in emotion/fear circuits. Heightened or blunted anticipatory responding to negative cues in adulthood may be due to differential trauma exposure during development, and previous trauma exposure in childhood may also modify effects of subsequent trauma in adulthood. The aim of the current investigation was to examine the contributions of childhood trauma on affective modulation of startle before and after trauma exposure in adulthood (a combat deployment). Adult male participants from the Marine Resilience Study with (n = 1145) and without (n = 1312) a history of reported childhood trauma completed an affective modulation of startle task to assess aversive anticipation. Affective startle response was operationalized by electromyography (EMG) recording of the orbicularis oculi muscle in response to acoustic stimuli when anticipating positive and negative affective images. Startle responses to affective images were also assessed. Testing occurred over three time-points; before going on a 7 month combat deployment and 3 and 6 months after returning from deployment. Startle response when anticipating negative images was greater compared to pleasant images across all three test periods. Across all 3 time points, childhood trauma was consistently associated with significantly blunted startle when anticipating negative images, suggesting reliable effects of childhood trauma on aversive anticipation. Conversely, deployment trauma was associated with increased startle reactivity post-deployment compared to pre-deployment, which was independent of childhood trauma and image valence. These results support the hypothesis that trauma exposure during development vs. adulthood may have dissociable effects on aversive anticipation and arousal mechanisms. Further study in women and across more refined age groups is needed to test generalizability and identify potential developmental windows for these differential effects.

Pyrethroid exposure among children residing in green versus non-green multi-family, low-income housing

BACKGROUND

There is growing concern about children's chronic low-level pesticide exposure and its impact on health. Green building practices (e.g., reducing leakage of the thermal and pressure barrier that surrounds the structure, integrated pest management, improved ventilation) have the potential to reduce pesticide exposure. However, the potential impact of living in green housing on children's pesticide exposure is unknown.

OBJECTIVE

To address this question, a longitudinal study of pyrethroid metabolites (3-phenoxybenzoic acid [3-PBA], 4-fluoro-3-phenoxybenzoic acid [4-F-3-PBA], trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane carboxylic acid [trans-DCCA]) in first morning void urine, collected from 68 children from New Orleans, Louisiana residing in green and non-green housing was conducted.

METHODS

Children were followed for 1 year with three repeated measures of pesticide exposure. Generalized estimating equations examined associations between housing type (green vs. non-green) and urinary pyrethroid metabolite concentrations adjusting for demographic and household factors over the year.

RESULTS

Ninety-five percent of samples had detectable concentrations of 3-PBA (limit of detection [LOD]: 0.1 μg/L); 8% of 4-F-3-PBA (LOD: 0.1 μg/L), and 12% of trans-DCCA (LOD: 0.6 μg/L). In adjusted models, green housing was not associated with statistically significant differences in children's 3-PBA urinary concentrations compared to non-green housing.

Reward-related distracters and working memory filtering

Reward-related stimuli capture attention, even when they are task irrelevant. A consequence of attentional prioritization of reward-related stimuli is that they may also have preferential access to working memory like other forms of emotional information. However, whether reward-related distracters leak into working memory remains unknown. Here, using a well-validated change detection task of visual working memory capacity and filtering, we conducted two studies to directly assess the impact of reward-related distracters on working memory. In both studies, the distracters consisted of colored bars or circles that were previously associated with monetary reward. In Experiment 1, results indicated that previously rewarded distracters did not impact behavioral measures of working memory filtering efficiency compared to neutral distracters. In Experiment 2, using ERPs, we measured the contralateral delay activity (CDA), a psychophysiological index of the number of items retained in working memory, to further assess filtering efficiency. We observed that the CDA for high reward distracters was similar to low reward and neutral distracters. However, in early trials, behavioral measures revealed that previously rewarded stimuli negatively impacted working memory capacity, an effect not observed with neutral distracters. This effect, though, was not found for the CDA in early trials. In summary, our findings across two studies suggest that attentional capture by task-irrelevant reward may have minimal impact on visual working memory-findings that have important implications for delineating the boundaries of reward-cognition interactions.

Attenuated prefrontal and temporal neural activity during working memory as a potential biomarker of suicidal ideation in veterans with PTSD

BACKGROUND

Suicide is a significant health concern among veterans, and suicidal ideation is a common and functionally debilitating condition that frequently precedes suicidal behavior. Characterizing neurobiological substrates associated with suicidal ideation in veterans may inform evaluation of risk for this population. Associations between suicidal ideation and functional abnormalities in prefrontal, temporal, and striatal regions supporting cognitive task performance have been documented in individuals with mood and psychotic disorders, suggesting a potential role for neurocognitive vulnerabilities in this condition. To date, however, relatively little research has explored neural correlates of suicidal ideation, particularly among individuals with posttraumatic stress disorder (PTSD).

METHODS

Twenty three combat veterans diagnosed with PTSD completed an adapted Reading Span (Rspan) working memory task during functional magnetic resonance imaging (fMRI). Participants were classified based on presence of current SI. We evaluated differences between these groups on neural activation in response to interference-based working memory demands within the task. Primary analyses were conducted using a voxel-wise between-group t-test.

RESULTS

Task-based activations were observed in regions including the cingulate, middle frontal, parietal, and occipital cortex, striatum, and cerebellum. Relative to individuals without SI, individuals with SI demonstrated less activation in a large region spanning the lateral prefrontal cortex and cingulate cortex, as well as the inferior temporal cortex, in response to interference demands.

CONCLUSIONS

Results are consistent with models proposing that prefrontal neural substrates involved in cognitive regulation are implicated in suicidal ideation. Involvement of temporal functioning may also exist based on current findings. Future research is needed to understand whether disturbances in prefrontal regulatory control reflect a specific profile subtype with distinct neural correlates, and how such neural patterns may be used to improve detection and treatment personalization.

Characterizing the neural circuitry associated with configural threat learning

Contextual threat learning is often associated with two processes: elemental and configural learning. Few studies have examined configural learning where subjects form a representation of the threat-related context as a gestalt whole from the individual features in the environment. The goal of the current study was to compare and contrast neural circuitry recruited by variation in demands placed on configural threat encoding. Subjects (N = 25) completed a configural threat learning task, where we manipulated the amount of configural encoding required to learn the threat association (low demand: changes to a discrete element of the context; and high demand: rearrangement of elements). US expectancy ratings, skin conductance responses (SCR), and functional magnetic resonance imaging (fMRI) were collected. Subjects successfully learned the configural threat association as measured by US expectancy ratings, SCR, and BOLD activity. Hippocampal and amygdala region of interest analyses indicated differential configural threat learning and predicted SCR measures of learning. Furthermore, whole brain analyses identified four circuits that were impacted by the amount of differential configural encoding required, but none correlated with SCR. These results set the stage for a more detailed understanding of how configural threat learning is instantiated in the brain-an important mechanism associated with PTSD and other fear-related disorders.

The Future of Contextual Fear Learning for PTSD Research: A Methodological Review of Neuroimaging Studies

There has been a great deal of recent interest in human models of contextual fear learning, particularly due to the use of such paradigms for investigating neural mechanisms related to the etiology of posttraumatic stress disorder. However, the construct of "context" in fear conditioning research is broad, and the operational definitions and methods used to investigate contextual fear learning in humans are wide ranging and lack specificity, making it difficult to interpret findings about neural activity. Here we will review neuroimaging studies of contextual fear acquisition in humans. We will discuss the methodology associated with four broad categories of how contextual fear learning is manipulated in imaging studies (colored backgrounds, static picture backgrounds, virtual reality, and configural stimuli) and highlight findings for the primary neural circuitry involved in each paradigm. Additionally, we will offer methodological recommendations for human studies of contextual fear acquisition, including using stimuli that distinguish configural learning from discrete cue associations and clarifying how context is experimentally operationalized.

Aversive distractors modulate affective working memory in frontoparietal regions

Rumination and worry are prominent symptoms of many psychiatric disorders. These symptoms compete for the same working memory (WM) storage space as those required for task-goals, leaving few cognitive resources available for successful goal-directed behavior. Once lodged in WM, negative information reduces cognitive control and further biases cognition toward affective stimuli. However, few studies have examined the neural mechanisms associated with maintaining affectively negative information in WM and the filtering of aversive distractors. Here, subjects completed an affective verbal WM task while distractor-cues that predicted aversive or positive stimuli were presented during the delay period while undergoing functional MRI (fMRI). Results revealed that during aversive distractors, there was a decrease in both dlPFC and PPC activity, but only when maintaining negative affective information in WM. Furthermore, dlPFC and PPC activity predicted behavioral performance. This pattern was not observed when maintaining positive words in WM or when positive distractors were presented. These findings demonstrate that the affective valence of the items stored in WM modulates "top-down" control networks necessary for the execution of cognitive control related to affective distractor interreference. Furthermore, these results provide a neurocognitive framework for understanding how rumination and worry produce negative downstream failures in cognitive control and emotion regulation. (PsycINFO Database Record (c) 2020 APA, all rights reserved).

Multimodal canonical correlation reveals converging neural circuitry across trauma-related disorders of affect and cognition

Trauma-related disorders of affect and cognition (TRACs) are associated with a high degree of diagnostic comorbidity, which may suggest that these disorders share a set of underlying neural mechanisms. TRACs are characterized by aberrations in functional and structural circuits subserving verbal memory and affective anticipation. Yet, it remains unknown how the neural circuitry underlying these multiple mechanisms contribute to TRACs. Here, in a sample of 47 combat Veterans, we measured affective anticipation using functional magnetic resonance imaging (fMRI), verbal memory with fluorodeoxyglucose positron emission tomography (FDG-PET), and grey matter volume with structural magnetic resonance imaging (sMRI). Using a voxel-based multimodal canonical correlation analysis (mCCA), the set of neural measures were statistically integrated, or fused, with a set of TRAC symptom measures including mild traumatic brain injury (mTBI), posttraumatic stress, and depression severity. The first canonical correlation pair revealed neural convergence in clusters encompassing the middle frontal gyrus and supplemental motor area, regions implicated in top-down cognitive control and affect regulation. These results highlight the potential of leveraging multivariate neuroimaging analysis for linking neurobiological mechanisms associated with TRACs, paving the way for transdiagnostic biomarkers and targets for treatment.

Abnormal cortical gyrification in criminal psychopathy

Background

Psychopathy is a personality disorder characterized by interpersonal and emotional abnormalities (e.g., lack of empathy and guilt) and antisocial behavior. Psychopathy has been associated with a number of structural brain abnormalities, most notably in orbital frontal and anterior/medial temporal regions, that may underlie psychopathic individuals' problematic behaviors. Past research evaluating cortical structure in psychopathy has considered thickness and volume, but to date no study has investigated differences in cortical gyrification, a measure of cortical complexity thought to reflect early neurodevelopmental cortical connectivity.

Methods

We measured the local gyrification index (LGI) in a sample of 716 adult male inmates and performed a whole brain analysis assessing the relationship between LGI and total and factor scores on the Hare Psychopathy Checklist-Revised (PCL-R).

Results

PCL-R scores were negatively associated with LGI measures within the right hemisphere in the midcingulate cortex (MCC) and adjacent regions of the superior frontal gyrus as well as lateral superior parietal cortex. Additionally, PCL-R Factor 1 scores (interpersonal/affective traits) predicted less LGI within the right MCC and adjacent dorsomedial frontal cortex and greater LGI in bilateral occipital cortex. Scores on PCL-R Factor 2, indicating impulsivity and antisocial behaviors, did not predict LGI in any regions.

Conclusions

These findings suggest that psychopathy, particularly the interpersonal and affective traits, are associated with specific structural abnormalities that form during neurodevelopment and these abnormalities may underlie aberrant brain functioning in regions important in emotional processing and cognitive control.

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We examined cortical gyrification associations with psychopathy in a sample of 716 incarcerated individuals.

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Psychopathy was negatively associated with gyrification in the midcingulate cortex and superior parietal cortex.

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Factor 1 scores negatively predicted gyrification in the midcingulate cortex, but positively in bilateral occipital cortex.

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These results may represent a vulnerability for psychopathy, which may help elucidate the etiology of this disorder.

Individual variation in working memory is associated with fear extinction performance

PTSD has been associated consistently with abnormalities in fear acquisition and extinction learning and retention. Fear acquisition refers to learning to discriminate between threat and safety cues. Extinction learning reflects the formation of a new inhibitory-memory that competes with a previously learned threat-related memory. Adjudicating the competition between threat memory and the new inhibitory memory during extinction may rely, in part, on cognitive processes such as working memory (WM). Despite significant shared neural circuits and signaling pathways the relationship between WM, fear acquisition, and extinction is poorly understood. Here, we analyzed data from a large sample of healthy Marines who underwent an assessment battery including tests of fear acquisition, extinction learning, and WM (N-back). Fear potentiated startle (FPS), fear expectancy ratings, and self-reported anxiety served as the primary dependent variables. High WM ability (N = 192) was associated with greater CS + fear inhibition during the late block of extinction and greater US expectancy change during extinction learning compared to individuals with low WM ability (N = 204). WM ability was not associated with magnitude of fear conditioning/expression. Attention ability was unrelated to fear acquisition or extinction supporting specificity of WM associations with extinction. These results support the conclusion that individual differences in WM may contribute to regulating fear responses.

Worry is associated with impaired gating of threat from working memory

Dispositional anxiety is a well-established risk factor for the development of anxiety and other emotional disorders. These disorders are common, debilitating, and challenging to treat, pointing to the need to understand the more elementary neurocognitive mechanisms that confer elevated risk. Importantly, many of the maladaptive behaviors characteristic of anxiety, such as worry, occur when threat is absent. This raises the possibility that worry reflects difficulties gating threat-related information from working memory--a limited capacity workspace that supports the maintenance, recall, and manipulation of information--and facilitates goal-directed thoughts and actions. Here, we tested, for the first time, whether trait-like individual differences in worry, a key facet of the anxious phenotype, reflect difficulties gating threat and neutral-related distracters from working memory. Results indicated that both dispositional worry and anxiety individually predicted the combined filtering cost of threat and neutral distracters. Importantly, worry was associated with inefficient filtering of threat-related, but not neutral, distracters from working memory. In contrast, dispositional anxiety was related to a similar level of threat and neutral filtering cost. Furthermore, dispositional anxiety's relationship to filtering of threat was predominantly driven by differences in worry. These results suggest that the propensity to worry is characterized by a failure to gate task-irrelevant threat from working memory. These results provide a framework for understanding the mechanisms underlying chronic worry and, more broadly, the cognitive architecture of dispositional anxiety.

A test house study of pesticides and pesticide degradation products following an indoor application

Preexisting pesticide degradates are a concern for pesticide biomonitoring studies as exposure to them may result in overestimation of pesticide exposure. The purpose of this research was to determine whether there was significant formation and movement, of pesticide degradates over a 5-week period in a controlled indoor setting after insecticide application. Movement of the pesticides during the study was also evaluated. In a simulated crack and crevice application, commercially available formulations of fipronil, propoxur, cis/trans-permethrin, and cypermethrin were applied to a series of wooden slats affixed to the wall in one room of an unoccupied test house. Floor surface samples were collected through 35 days post-application. Concentrations of the pesticides and the following degradates were determined: 2-iso-propoxyphenol, cis/trans 3-(2,2-dichlorovinyl)-3-3-dimethyl-(1-cyclopropane) carboxylic acid, 3-phenoxybenzoic acid, fipronil sulfone, fipronil sulfide, and fipronil desulfinyl. Deltamethrin, which had never been applied, and chlorpyrifos, which had been applied several years earlier, and their degradation products, cis-3-(2,2-dibromovinyl)-2,2-dimethylcyclopropane-1-carboxylic acid, and, 3,5,6-trichloro-2-pyridinol, respectively, were also measured. Propoxur was the only insecticide with mass movement away from the application site. There was no measurable formation or movement of the degradates. However, all degradates were present at low levels in the formulated product. These results indicate longitudinal repetitive sampling of indoor degradate levels during short-term studies, is unnecessary.

PRACTICAL IMPLICATIONS

Exposure to preexisting pesticide degradates may inflate estimates of exposure in biomonitoring studies where these compounds are used as biomarkers. To date, there is no published information on formation of pesticide degradates following an indoor application. We found that the study pesticides have low rates of degradation and are unlikely to be a significant factor affecting results of short-term (weeks) biomonitoring studies. Therefore, relatively few indoor samples are needed to estimate background levels of degradation products resulting from a recent pesticide application.

The interplay of attention and emotion: top-down attention modulates amygdala activation in psychopathy

Psychopathic behavior has long been attributed to a fundamental deficit in fear that arises from impaired amygdala function. Growing evidence has demonstrated that fear-potentiated startle (FPS) and other psychopathy-related deficits are moderated by focus of attention, but to date, no work on adult psychopathy has examined attentional modulation of the amygdala or concomitant recruitment of relevant attention-related circuitry. Consistent with previous FPS findings, here we report that psychopathy-related differences in amygdala activation appear and disappear as a function of goal-directed attention. Specifically, decreased amygdala activity was observed in psychopathic offenders only when attention was engaged in an alternative goal-relevant task prior to presenting threat-relevant information. Under this condition, psychopaths also exhibited greater activation in selective-attention regions of the lateral prefrontal cortex (LPFC) than did nonpsychopaths, and this increased LPFC activation mediated psychopathy's association with decreased amygdala activation. In contrast, when explicitly attending to threat, amygdala activation did not differ in psychopaths and nonpsychopaths. This pattern of amygdala activation highlights the potential role of LPFC in mediating the failure of psychopathic individuals to process fear and other important information when it is peripheral to the primary focus of goal-directed attention.

Failure to filter: anxious individuals show inefficient gating of threat from working memory

Dispositional anxiety is a well-established risk factor for the development of psychiatric disorders along the internalizing spectrum, including anxiety and depression. Importantly, many of the maladaptive behaviors characteristic of anxiety, such as anticipatory apprehension, occur when threat is absent. This raises the possibility that anxious individuals are less efficient at gating threat's access to working memory, a limited capacity workspace where information is actively retained, manipulated, and used to flexibly guide goal-directed behavior when it is no longer present in the external environment. Using a well-validated neurophysiological index of working memory storage, we demonstrate that threat-related distracters were difficult to filter on average and that this difficulty was exaggerated among anxious individuals. These results indicate that dispositionally anxious individuals allocate excessive working memory storage to threat, even when it is irrelevant to the task at hand. More broadly, these results provide a novel framework for understanding the maladaptive thoughts and actions characteristic of internalizing disorders.

Comparison of wipe materials and wetting agents for pesticide residue collection from hard surfaces

Different wipe materials and wetting agents have been used to collect pesticide residues from surfaces, but little is known about their comparability. To inform the selection of a wipe for the National Children's Study, the analytical feasibility, collection efficiency, and precision of Twillwipes wetted with isopropanol (TI), Ghost Wipes (GW), and Twillwipes wetted with water (TW), were evaluated. Wipe samples were collected from stainless steel surfaces spiked with high and low concentrations of 27 insecticides, including organochlorines, organophosphates, and pyrethroids. Samples were analyzed by GC/MS/SIM. No analytical interferences were observed for any of the wipes. The mean percent collection efficiencies across all pesticides for the TI, GW, and TW were 69.3%, 31.1%, and 10.3% at the high concentration, respectively, and 55.6%, 22.5%, and 6.9% at the low concentration, respectively. The collection efficiencies of the TI were significantly greater than that of GW or TW (p<0.0001). Collection efficiency also differed significantly by pesticide (p<0.0001) and spike concentration (p<0.0001). The pooled coefficients of variation (CVs) of the collection efficiencies for the TI, GW, and TW at high concentration were 0.08, 0.17, and 0.24, respectively. The pooled CV of the collection efficiencies for the TI, GW, and TW at low concentration were 0.15, 0.19, and 0.36, respectively. The TI had significantly lower CVs than either of the other two wipes (p=0.0008). Though the TI was superior in terms of both accuracy and precision, it requires multiple preparation steps, which could lead to operational challenges in a large-scale study.

American Healthy Homes Survey: a national study of residential pesticides measured from floor wipes

The U.S. Department of Housing and Urban Development in collaboration with the United States Environmental Protection Agency conducted a survey measuring lead, allergens, and insecticides in a randomly selected nationally representative sample of residential homes. Multistage sampling with clustering was used to select the 1131 homes of which a subset of 500 randomly selected homes included the collection of hard surface floor wipes. Samples were collected by trained field technicians between June 2005 and March 2006 using isopropanol wetted wipes. Samples were analyzed for a suite of 24 compounds which included insecticides in the organochlorine, organophosphate, pyrethroid and phenylpyrazole classes, and the insecticide synergist piperonyl butoxide. The most commonly detected were permethrin (89%), chlorpyrifos (78%), chlordane (64%), piperonyl butoxide (52%), cypermethrin (46%), and fipronil (40%). Mean and geometric mean (GM) concentrations varied widely among compounds, but were highest for trans-permethrin (mean 2.22 ng/cm2 and GM 0.14 ng/ cm2) and cypermethrin (mean 2.9 ng/cm2 and GM 0.03 ng/ cm2). Results show that most floors in occupied homes in the U.S. have measurable levels of insecticides that may serve as sources of exposure to occupants.

An observational study of the potential for human exposures to pet-borne diazinon residues following lawn applications

This study examined the potential for pet dogs to be an important pathway for transporting diazinon residues into homes and onto its occupants following residential lawn applications. The primary objectives were to investigate the potential exposures of occupants and their pet dogs to diazinon after an application to turf at their residences and to determine if personal contacts between occupants and their pet dogs resulted in measurable exposures. It was conducted from April to August 2001 before the Agency phased out all residential uses of diazinon in December 2004. Six families and their pet dogs were recruited into the study. Monitoring was conducted at pre-, 1, 2, 4, and 8 days post-application of a commercial, granular formulation of diazinon to the lawn by the homeowner. Environmental samples collected included soil, indoor air, carpet dust, and transferable residues from lawns and floors. Samples collected from the pet dogs consisted of paw wipes, fur clippings, and transferable residues from the fur by a technician or child wearing a cotton glove(s). First morning void (FMV) urine samples were collected from each child and his/her parent on each sampling day. Diazinon was analyzed in all samples, except urine, by GC-MS. The metabolite 2-isopropyl-4-methyl-6-hydroxypyrimidine (IMPy) was analyzed in the urine samples by HPLC-MS/MS. Mean airborne residues of diazinon on day 1 post-application were at least six times higher in both the living rooms (235+/-267 ng/m(3)) and children's bedrooms (179+/-246 ng/m(3)) than at pre-application. Mean loadings of diazinon in carpet dust samples were at least 20 times greater on days 2, 4, and 8 post-application than mean loadings (0.03+/-0.04 ng/cm(2)) at pre-application. The pet dogs had over 900 times higher mean loadings of diazinon residues on their paws on day 1 post-application (88.1+/-100.1 ng/cm(2)) compared to mean loadings (<0.09 ng/cm(2)) at pre-application. The mean diazinon loadings on the fur clippings were at least 14 times higher on days 1, 2, 4, and 8 post-application than mean loadings (0.8+/-0.4 ng/cm(2)) at pre-application. For transferable residues from dog fur, the mean loadings of diazinon on the technician's cotton glove samples were the lowest before application (0.04+/-0.08 ng/cm(2)) and the highest on day 1 post-application (10.4+/-23.9 ng/cm(2)) of diazinon to turf. Urinary IMPy concentrations for the participants ranged from <0.3 to 5.5 ng/mL before application and <0.3-12.5 ng/mL after application of diazinon. The mean urinary IMPy concentrations for children or adults were not statistically different (p>0.05) at pre-application compared to post-application of diazinon to turf. The results showed that the participants and their pet dogs were likely exposed to low levels of diazinon residues from several sources (i.e., air, dust, and soil), through several pathways and routes, after lawn applications at these residences. Lastly, the pet dog appears to be an important pathway for the transfer and translocation of diazinon residues inside the homes and likely exposed occupants through personal contacts (i.e., petting).

A preliminary examination of the translocation of microencapsulated cyfluthrin following applications to the perimeter of residential dwellings

Methods have been developed to monitor the translocation of microencapsulated cyfluthrin following perimeter applications to residential dwellings. A pilot study was implemented to determine both the potential for application spray to drift away from dwellings and the intrusion of residues into homes following perimeter treatments. Residential monitoring included measuring spray drift using cellulose filter paper and the collection of soil samples from within the spray zone. In addition, interior air was monitored using fiberglass filter paper as a sorbent medium and cotton ball swabs were used to collect surface wipes. Fortification of matrixes resulted in recoveries of > 90%. Spray drift was highest at the point of application and declined to low but measurable levels 9.1 m from the foundations of dwellings. Soil residues declined to low, but measurable levels by 45 days post-application. No cyfluthrin was measured from indoor air; however, some interior surfaces had detectable levels of cyfluthrin until three days post-application. Findings indicate that spray drift resulting from perimeter applications might contaminate non-target surfaces outside the spray zone. Soil borne residues may serve as persistent sources for human exposure and potentially intrude into dwellings through the activities of occupants and pets. Residues do not appreciably translocate through air and consequently inhalation is not a likely route for human exposure. Surface residues detected indoors suggest that the physical movement of residues from the exterior to the interior might be a viable route of movement of residues following this type of application.

Structure-activity studies for a novel series of N-(arylethyl)-N-(1,2,3,4-tetrahydronaphthalen-1-ylmethyl)-N-methylamine s possessing dual 5-HT uptake inhibiting and alpha2-antagonistic activities

In search of an alpha2-antagonist/5-HT uptake inhibitor as a potential new class of antidepressant with a more rapid onset of action, compound 3 was prepared and observed to possess high affinity for the alpha2-receptor (K(i) = 6.71 nM) and the 5-HT uptake site (20.6 nM). A series of tertiary amine analogs of 3 were synthesized and assayed for their affinity at both the alpha2-receptor and the 5-HT uptake site. The structure-activity relationship reveals that a variety of structural modifications to the arylethyl fragment are possible with retention of this dual activity. On the tetralin portion, 5-OMe substitution and the (R) stereochemistry at C-1 are optimal with alternate substitutions producing compounds retaining high affinity for the alpha2-receptor but lacking affinity for the 5-HT uptake site. Data for several rigidified 5-O-alkyl analogs suggests that the favored orientation of the oxygen lone pairs may be away from the 6-position of the tetralin.

Mono- and bis(aminomethyl)phenylacetic acid esters as short-acting antiarrhythmic agents. 2

The synthesis, antiarrhythmic activity, and blood hydrolysis properties of a series of mono- and bis(aminomethyl)phenylacetic acid esters related to a previously reported class Ic antiarrhythmic agent (ACC-9358) are described. Of the various oxa-, aza-, thia-, and carbacyclic esters initially prepared in the bis(pyrrolidinomethyl)-4-hydroxyphenylacetic acid series, the 1,4-benzodioxanyl-2-methyl(3q) and the thienyl-2-methyl(31) esters were evaluated in vivo for antiarrhythmic efficacy. In addition, a number of monoappended phenylacetic esters of 3q with or without the 4-hydroxy group were also prepared for evaluation of antiarrhythmic, lipophilic, and metabolic properties. Of these compounds, 3q possessed the most desirable pharmacological and pharmacokinetic profile.

Ester derivatives of 2,6-bis(1-pyrrolidinylmethyl)-4-benzamidophenol as short-acting antiarrhythmic agents. 1

In an effort to find a replacement for the iv antiarrhythmic drug lidocaine having reduced systemic and central nervous system effects, activity against supraventricular as well as ventricular arrhythmias, and a biological half-life of less than 15 min, derivatives of the orally active class Ic clinical agent 2,6-bis(1-pyrrolidinylmethyl)-4-benzamidophenol, 1 (ACC-9358), were synthesized and tested. Compounds with ester groups attached to the phenyl ring were either weakly active or toxic. Replacement of the formanilide function with alkyl esters afforded compounds with antiarrhythmic activity in the range of 1. When the ester carboxyl was separated from the bis(aminomethyl)phenol by methylene units, very short half-lives were observed in human blood. In general, these compounds also had low lipophilic character.

Synthesis and antiarrhythmic and parasympatholytic properties of substituted phenols. 3. Modifications to the linkage region (region 3)

As part of a continuing program of systematically modifying the structure of the class I antiarrhythmic drug changrolin, we synthesized 15 analogues in which the linkage between the two aromatic regions was altered. High antiarrhythmic activity and low parasympatholytic activity was found when the linkage region, designated region 3, contained a carbonyl moiety, including ketones, amides, and ureas. Secondary amides were superior to tertiary amides, while amide reversal resulted in no change in activities. One compound in this series, 7, 2,6-bis(1-pyrrolidinyl-methyl)-4-benzamidophenol (ACC-9358), is undergoing preclinical evaluations.

Synthesis and antiarrhythmic and parasympatholytic properties of substituted phenols. 2. Amides

Thirty amides patterned after the antiarrhythmic drug changrolin were synthesized and their antiarrhythmic and parasympatholytic activities were assessed. There was no correlation between antiarrhythmic and parasympatholytic activities. Several of the amides were found to be potent antiarrhythmic agents that possessed low parasympatholytic activity. All of the compounds appear to act by a class I mechanism.

Synthesis and antiarrhythmic and parasympatholytic properties of substituted phenols. 1. Heteroarylamine derivatives

Twenty-four structural derivatives of the antiarrhythmic drug changrolin were synthesized and tested for antiarrhythmic and parasympatholytic activities. It was found that while the bis(pyrrolidinylmethyl)phenol pattern of changrolin appeared to be optimal in this series, a wide latitude existed for the heteroaryl substituent for maintaining good antiarrhythmic activity. Further, the antiarrhythmic and parasympatholytic activities tended to exhibit parallel changes.

N-Aralkyl substitution of 2-amino-5,6- and -6,7-dihydroxy-1,2,3,4-tetrahydronaphthalenes. 2. Derivatives of a hypotensive-positive inotropic agent

Seven derivatives of 2-[[2-(3,4-dihydroxyphenyl)-1-methylethyl]amino]-6,7-dihydroxy-1,2,3,4- tetrahydronaphthalene, an inotropic agent which also causes a decrease in blood pressure, were synthesized and tested for inotropic potency, cardioselectivity, and inotropic selectivity. The derivatives were designed to explore whether catechol moieties and rigid rotamers of dopamine are necessary for the activity which was found in the parent compound. The derivatives had phenolic functions in place of catechols, and they had phenethylamine in place of the tetrahydronaphthalene moiety. In no case was the profile of activity of the parent compound duplicated in the derivatives.

N-Aralkyl substitution of 2-amino-5,6- and -6,7-dihydroxy-1,2,3,4-tetrahydronaphthalenes. 1. Cardiac and pressor/depressor activities

Amino substitution o rigid forms of dopamine [2-amino-5,6-dihydroxy-1,2,3,4-tetrahydronaphthalene (A-5,6-DTN) and 2-amino-6,7-dihydroxy-1,2,3,4-tetrahydronaphthalene (A-6,7-DTN)] with aralkyl functionalities was carried out to investigate the role of such structural modifications upon cardiac inotropic/chronotropic and blood pressure activity. Derivatives of A-5,6-DTN were strong vasodepressor agents devoid action was associated with the dihydroxyphenyl-1-methylethyl derivative, which was also an inotropic selective compound. The amino substituent of dobutamine was ineffective in reducing peripheral vascular action when combined with the rigid forms of dopamine. It was also ineffective in imparting inotropic selectivity when combined with A-5,6-DTN. An analysis of these observations in light of existing structure-activity relationships of aminoaralkyl substitution of other catecholamine structure is presented.