Action-value processing underlies the role of the dorsal anterior cingulate cortex in performance monitoring during self-regulation of affect

In this study, we merged methods from engineering control theory, machine learning, and human neuroimaging to critically test the putative role of the dorsal anterior cingulate cortex (dACC) in goal-directed performance monitoring during an emotion regulation task. Healthy adult participants (n = 94) underwent cued-recall and re-experiencing of their responses to affective image stimuli with concurrent functional magnetic resonance imaging and psychophysiological response recording. During cued-recall/re-experiencing trials, participants engaged in explicit self-regulation of their momentary affective state to match a pre-defined affective goal state. Within these trials, neural decoding methods measured affect processing from fMRI BOLD signals across the orthogonal affective dimensions of valence and arousal. Participants’ affective brain states were independently validated via facial electromyography (valence) and electrodermal activity (arousal) responses. The decoded affective states were then used to contrast four computational models of performance monitoring (i.e., error, predicted response outcome, action-value, and conflict) by their relative abilities to explain emotion regulation task-related dACC activation. We found that the dACC most plausibly encodes action-value for both valence and arousal processing. We also confirmed that dACC activation directly encodes affective arousal and also likely encodes recruitment of attention and regulation resources. Beyond its contribution to improving our understanding of the roles that the dACC plays in emotion regulation, this study introduced a novel analytical framework through which affect processing and regulation may be functionally dissociated, thereby permitting mechanistic analysis of real-world emotion regulation strategies, e.g., distraction and reappraisal, which are widely employed in cognitive behavioral therapy to address clinical deficits in emotion regulation.

Lessons learned: A neuroimaging research center's transition to open and reproducible science

Human functional neuroimaging has evolved dramatically in recent years, driven by increased technical complexity and emerging evidence that functional neuroimaging findings are not generally reproducible. In response to these trends, neuroimaging scientists have developed principles, practices, and tools to both manage this complexity as well as to enhance the rigor and reproducibility of neuroimaging science. We group these best practices under four categories: experiment pre-registration, FAIR data principles, reproducible neuroimaging analyses, and open science. While there is growing recognition of the need to implement these best practices there exists little practical guidance of how to accomplish this goal. In this work, we describe lessons learned from efforts to adopt these best practices within the Brain Imaging Research Center at the University of Arkansas for Medical Sciences over 4 years (July 2018-May 2022). We provide a brief summary of the four categories of best practices. We then describe our center's scientific workflow (from hypothesis formulation to result reporting) and detail how each element of this workflow maps onto these four categories. We also provide specific examples of practices or tools that support this mapping process. Finally, we offer a roadmap for the stepwise adoption of these practices, providing recommendations of why and what to do as well as a summary of cost-benefit tradeoffs for each step of the transition.

A test of affect processing bias in response to affect regulation

In this study we merged methods from machine learning and human neuroimaging to test the role of self-induced affect processing states in biasing the affect processing of subsequent image stimuli. To test this relationship we developed a novel paradigm in which (n = 40) healthy adult participants observed affective neural decodings of their real-time functional magnetic resonance image (rtfMRI) responses as feedback to guide explicit regulation of their brain (and corollary affect processing) state towards a positive valence goal state. By this method individual differences in affect regulation ability were controlled. Attaining this brain-affect goal state triggered the presentation of pseudo-randomly selected affectively congruent (positive valence) or incongruent (negative valence) image stimuli drawn from the International Affective Picture Set. Separately, subjects passively viewed randomly triggered positively and negatively valent image stimuli during fMRI acquisition. Multivariate neural decodings of the affect processing induced by these stimuli were modeled using the task trial type (state- versus randomly-triggered) as the fixed-effect of a general linear mixed-effects model. Random effects were modeled subject-wise. We found that self-induction of a positive valence brain state significantly positively biased valence processing of subsequent stimuli. As a manipulation check, we validated affect processing state induction achieved by the image stimuli using independent psychophysiological response measures of hedonic valence and autonomic arousal. We also validated the predictive fidelity of the trained neural decoding models using brain states induced by an out-of-sample set of image stimuli. Beyond its contribution to our understanding of the neural mechanisms that bias affect processing, this work demonstrated the viability of novel experimental paradigms triggered by pre-defined cognitive states. This line of individual differences research potentially provides neuroimaging scientists with a valuable tool for exploring the roles and identities of intrinsic cognitive processing mechanisms that shape our perceptual processing of sensory stimuli.

L-DOPA and consolidation of fear extinction learning among women with posttraumatic stress disorder

This study tested whether L-DOPA delivered during the consolidation window following fear extinction learning reduces subsequent fear responding among women with PTSD. Adult women diagnosed with PTSD completed a contextual fear acquisition and extinction task during fMRI and then immediately received either placebo (n = 34), 100/25 mg L-DOPA/carbidopa (n = 28), or 200/50 mg L-DOPA/carbidopa (n = 29). Participants completed a resting-state scan before the task and again 45 min following drug ingestion to characterize effects of L-DOPA on extinction memory neural reactivation patterns during consolidation. Twenty-four hours later, participants returned for tests of context renewal, extinction recall, and reinstatement during fMRI with concurrent skin conductance responding (SCR) assessment. Both active drug groups demonstrated increased reactivation of extinction encoding in the amygdala during the post-task resting-state scan. For SCR data, both drug groups exhibited decreased Day 2 reinstatement across all stimuli compared to placebo, and there was some evidence for decreased context renewal to the fear stimulus in the 100 mg group compared to placebo. For imaging data, both drug groups demonstrated decreased Day 2 reinstatement across stimuli in a bilateral insula network compared to placebo. There was no evidence in SCR or neural activity that L-DOPA improved extinction recall. Reactivation of extinction encodings in the amygdala during consolidation on Day 1 predicted Day 2 activation of the insula network. These results support a role for dopamine during the consolidation window in boosting reactivation of amygdala extinction encodings and reducing reinstatement, but not improving extinction recall, in women with PTSD.

Intertemporal decision-making-related brain states predict adolescent drug abuse intervention responses

Adolescent drug misuse represents a major risk factor for long-term drug use disorders. However, wide individual differences in responses to first-line behavioral therapies targeting adolescent drug misuse limit critical early intervention. Identifying the neural signatures of those adolescents most likely to respond to an intervention would potentially guide personalized strategies for reducing drug misuse. Prior to a 14-week evidence-based intervention involving combinations of contingency management, motivational enhancement, and cognitive behavioral therapy, thirty adolescent alcohol and/or cannabis users underwent fMRI while performing a reward delay discounting (DD) task tapping an addiction-related cognition. Intervention responses were longitudinally characterized by both urinalysis and self-report measures of the percentage of days used during treatment and in post-treatment follow-up. Group independent component analysis (ICA) of task fMRI data identified neural processing networks related to DD task performance. Separate measures of wholesale recruitment during immediate reward choices and within-network functional connectivity among selective networks significantly predicted intervention-related changes in drug misuse frequency. Specifically, heightened pre-intervention engagement of a temporal lobe "reward motivation" network for impulsive choices on the DD task predicted poorer intervention outcomes, while modes of functional connectivity within the reward motivation network, a prospection network, and a posterior insula network demonstrated robust associations with intervention outcomes. Finally, the pre-intervention functional organization of the prospection network also predicted post-intervention drug use behaviors for up to 6 months of follow-up. Multiple functional variations in the neural processing networks supporting preference for immediate and future rewards signal individual differences in readiness to benefit from an effective behavioral therapy for reducing adolescent drug misuse. The implications for efforts to boost therapy responses are discussed.

Does development moderate the effect of early life assaultive violence on resting-state networks? An exploratory study

Current neurocircuitry models of PTSD do not account for developmental effects, despite that early life assaultive violence is a potent risk factor for PTSD. Here, we preliminarily evaluated developmental stage as a moderator of the effect of early life assaultive violence on resting-state connectivity amongst regions associated with emotion generation and regulation using fMRI. Participants were adult women (n = 25) and adolescent girls (n = 36) who had or had not experienced early life assaultive violence. We found significant interactions between developmental stage and trauma exposure on resting-state functional connectivity (FC). Left amygdala connectivity with the left ventral anterior cingulate gyrus (BA 32) was reduced among trauma-exposed compared to control adolescents, but increased among trauma-exposed compared to control adults. A corresponding pattern of results was identified for FC between rostral anterior cingulate gyrus seed region and a similar right ventral anterior superior frontal gyrus cluster. Increased FC in both regions for assaulted adult women scaled positively with self-reported emotion regulation difficulties. Our results should be viewed tentatively due to sample limitations, but provide impetus to examine whether neurocircuitry models of PTSD may be strengthened by accounting for developmental stage.

The neural representation of the association between comorbid drug use disorders and childhood maltreatment

BACKGROUND

Comorbidity of drug use disorders (DUD) with other psychopathology is associated with worse functional and treatment outcomes than DUD alone. The present study sought to identify altered functional neural circuitry underlying DUD comorbidity with other psychiatric disorders, and model the relationship of these alterations to childhood trauma (Childhood Trauma Questionnaire) and negative self-beliefs (Beck Depression Inventory).

METHODS

A sample of adult men and women (mean = 36.8 years) with childhood maltreatment histories (n = 81) was allocated into the following groups based on psychiatric diagnoses and drug use history: no current or past psychiatric disorders (trauma control sample, n = 20), DUD only (n = 22), psychopathology only (n = 20), and DUD comorbid with other psychiatric illness (DCoP, n = 25).

RESULTS

Multiple regression of seed-based resting-state fMRI, controlling for age and sex, identified a functional connection between the right rostral anterior cingulate cortex (rACC) and left temporoparietal junction (TPJ) that was significantly increased in DCoP females, relative to the other clinical and control groups. Within the DCoP female sample, mediation analysis demonstrated that strength of connectivity between the subgenual cingulate cortex and both the right anterior insula and rostral lateral prefrontal cortex significantly mediated the relationship between increasing physical abuse and self-criticism with age as a moderator.

CONCLUSIONS

This study related sex-dependent alterations in functional organization of the prefrontal cortex with DCoP that are, in turn, related to magnitude of negative self-beliefs to childhood trauma exposure. Additionally, DCoP-selective alterations in rACC connectivity suggest that the neural correlates of DCoP do not represent linear additive contributions from two independent disorders.

Common Functional Brain States Encode both Perceived Emotion and the Psychophysiological Response to Affective Stimuli

Multivariate pattern analysis (MVPA) of functional magnetic resonance imaging (fMRI) data has critically advanced the neuroanatomical understanding of affect processing in the human brain. Central to these advancements is the brain state, a temporally-succinct fMRI-derived pattern of neural activation, which serves as a processing unit. Establishing the brain state's central role in affect processing, however, requires that it predicts multiple independent measures of affect. We employed MVPA-based regression to predict the valence and arousal properties of visual stimuli sampled from the International Affective Picture System (IAPS) along with the corollary skin conductance response (SCR) for demographically diverse healthy human participants (n = 19). We found that brain states significantly predicted the normative valence and arousal scores of the stimuli as well as the attendant individual SCRs. In contrast, SCRs significantly predicted arousal only. The prediction effect size of the brain state was more than three times greater than that of SCR. Moreover, neuroanatomical analysis of the regression parameters found remarkable agreement with regions long-established by fMRI univariate analyses in the emotion processing literature. Finally, geometric analysis of these parameters also found that the neuroanatomical encodings of valence and arousal are orthogonal as originally posited by the circumplex model of dimensional emotion.

Personality variables modify the relationship between childhood maltreatment history and poor functional outcomes

Childhood maltreatment history is a prevalent risk factor for substance use disorder and has lifelong adverse consequences on psychiatric wellbeing. The role of personality variations in determining childhood maltreatment-associated outcomes is poorly understood. This study sought to test neuroticism and agreeableness as mediator and moderator, respectively, of functional outcomes associated with having a history of childhood maltreatment and presence/absence of cocaine dependence. Ninety-four participants completed the Structured Clinical Interview for DSM-IV (SCID-IV), Childhood Trauma Questionnaire (CTQ), NEO-Five Factor Inventory (NEO-FFI), and the Addiction Severity Index (ASI). The distribution-of-the-product strategy tested if neuroticism mediated the relationship between CTQ and ASI scores. Agreeableness was tested as a moderator using bootstrapped multiple regression analyses with agreeableness*CTQ interaction terms as predictors of ASI scores. Analyses covaried for cocaine dependence to determine its influence. Neuroticism mediated the relationship between severity of childhood maltreatment history and family (ASI-Family) and psychiatric (ASI-Psychiatric) dysfunction in adulthood, independent of cocaine dependence. Agreeableness negatively moderated the effect of childhood maltreatment severity on family dysfunction. Exposure to emotional neglect and abuse selectively drove the mediation and moderation effects. Personality-directed interventions that reduce neuroticism or increase agreeableness may be promising approaches to uncouple childhood maltreatment history from lifelong social and psychiatric dysfunction.

Altered neural encoding of prediction errors in assault-related posttraumatic stress disorder

Posttraumatic stress disorder (PTSD) is widely associated with deficits in extinguishing learned fear responses, which relies on mechanisms of reinforcement learning (e.g., updating expectations based on prediction errors). However, the degree to which PTSD is associated with impairments in general reinforcement learning (i.e., outside of the context of fear stimuli) remains poorly understood. Here, we investigate brain and behavioral differences in general reinforcement learning between adult women with and without a current diagnosis of PTSD. 29 adult females (15 PTSD with exposure to assaultive violence, 14 controls) underwent a neutral reinforcement-learning task (i.e., two arm bandit task) during fMRI. We modeled participant behavior using different adaptations of the Rescorla-Wagner (RW) model and used Independent Component Analysis to identify timecourses for large-scale a priori brain networks. We found that an anticorrelated and risk sensitive RW model best fit participant behavior, with no differences in computational parameters between groups. Women in the PTSD group demonstrated significantly less neural encoding of prediction errors in both a ventral striatum/mPFC and anterior insula network compared to healthy controls. Weakened encoding of prediction errors in the ventral striatum/mPFC and anterior insula during a general reinforcement learning task, outside of the context of fear stimuli, suggests the possibility of a broader conceptualization of learning differences in PTSD than currently proposed in current neurocircuitry models of PTSD.

Brain States That Encode Perceived Emotion Are Reproducible but Their Classification Accuracy Is Stimulus-Dependent

The brain state hypothesis of image-induced affect processing, which posits that a one-to-one mapping exists between each image stimulus and its induced functional magnetic resonance imaging (fMRI)-derived neural activation pattern (i.e., brain state), has recently received support from several multivariate pattern analysis (MVPA) studies. Critically, however, classification accuracy differences across these studies, which largely share experimental designs and analyses, suggest that there exist one or more unaccounted sources of variance within MVPA studies of affect processing. To explore this possibility, we directly demonstrated strong inter-study correlations between image-induced affective brain states acquired 4 years apart on the same MRI scanner using near-identical methodology with studies differing only by the specific image stimuli and subjects. We subsequently developed a plausible explanation for inter-study differences in affective valence and arousal classification accuracies based on the spatial distribution of the perceived affective properties of the stimuli. Controlling for this distribution improved valence classification accuracy from 56% to 85% and arousal classification accuracy from 61% to 78%, which mirrored the full range of classification accuracy across studies within the existing literature. Finally, we validated the predictive fidelity of our image-related brain states according to an independent measurement, autonomic arousal, captured via skin conductance response (SCR). Brain states significantly but weakly (r = 0.08) predicted the SCRs that accompanied individual image stimulations. More importantly, the effect size of brain state predictions of SCR increased more than threefold (r = 0.25) when the stimulus set was restricted to those images having group-level significantly classifiable arousal properties.

Large-scale brain organization during facial emotion processing as a function of early life trauma among adolescent girls

Background

A wealth of research has investigated the impact of early life trauma exposure on functional brain activation during facial emotion processing and has often demonstrated amygdala hyperactivity and weakened connectivity between amygdala and medial PFC (mPFC). There have been notably limited investigations linking these previous node-specific findings into larger-scale network models of brain organization.

Method

To address these gaps, we applied graph theoretical analyses to fMRI data collected during a facial emotion processing task among 88 adolescent girls (n = 59 exposed to direct physical or sexual assault; n = 29 healthy controls), aged 11-17, during fMRI. Large-scale organization indices of modularity, assortativity, and global efficiency were calculated for stimulus-specific functional connectivity using an 883 region-of-interest parcellation.

Results

Among the entire sample, more severe early life trauma was associated with more modular and assortative, but less globally efficient, network organization across all stimulus categories. Among the assaulted girls, severity of early life trauma and PTSD diagnoses were both simultaneously related to increased modular brain organization. We also found that more modularized network organization was related both to amygdala hyperactivation and weakened connectivity between amygdala and medial PFC.

Conclusions

These results demonstrate that early life trauma is associated with enhanced brain organization during facial emotion processing and that this pattern of brain organization might explain the commonly observed association between childhood trauma and amygdala hyperactivity and weakened connectivity with mPFC. Implications of these results for neurocircuitry models are discussed.

Distributed Neural Processing Predictors of Multi-dimensional Properties of Affect

Recent evidence suggests that emotions have a distributed neural representation, which has significant implications for our understanding of the mechanisms underlying emotion regulation and dysregulation as well as the potential targets available for neuromodulation-based emotion therapeutics. This work adds to this evidence by testing the distribution of neural representations underlying the affective dimensions of valence and arousal using representational models that vary in both the degree and the nature of their distribution. We used multi-voxel pattern classification (MVPC) to identify whole-brain patterns of functional magnetic resonance imaging (fMRI)-derived neural activations that reliably predicted dimensional properties of affect (valence and arousal) for visual stimuli viewed by a normative sample (n = 32) of demographically diverse, healthy adults. Inter-subject leave-one-out cross-validation showed whole-brain MVPC significantly predicted (p < 0.001) binarized normative ratings of valence (positive vs. negative, 59% accuracy) and arousal (high vs. low, 56% accuracy). We also conducted group-level univariate general linear modeling (GLM) analyses to identify brain regions whose response significantly differed for the contrasts of positive versus negative valence or high versus low arousal. Multivoxel pattern classifiers using voxels drawn from all identified regions of interest (all-ROIs) exhibited mixed performance; arousal was predicted significantly better than chance but worse than the whole-brain classifier, whereas valence was not predicted significantly better than chance. Multivoxel classifiers derived using individual ROIs generally performed no better than chance. Although performance of the all-ROI classifier improved with larger ROIs (generated by relaxing the clustering threshold), performance was still poorer than the whole-brain classifier. These findings support a highly distributed model of neural processing for the affective dimensions of valence and arousal. Finally, joint error analyses of the MVPC hyperplanes encoding valence and arousal identified regions within the dimensional affect space where multivoxel classifiers exhibited the greatest difficulty encoding brain states – specifically, stimuli of moderate arousal and high or low valence. In conclusion, we highlight new directions for characterizing affective processing for mechanistic and therapeutic applications in affective neuroscience.

Neural activity during attentional conflict predicts reduction in tinnitus perception following rTMS

BACKGROUND

Subjective idiopathic tinnitus is an intrusive, distracting, and potentially disabling disorder characterized by phantom perception of sounds. Although tinnitus has no approved pharmacologic treatment, recent evidence supports the use of repetitive transcranial magnetic stimulation (rTMS) to alleviate tinnitus symptoms.

OBJECTIVE/HYPOTHESIS

Repetitive TMS delivered over the middle superior temporal gyrus (STG) may alter ratings of tinnitus awareness and annoyance more than loudness due to change in attentional processing. STG has reciprocal connections to regions of the prefrontal cortex that mediate attention. To probe the hypothesized influence of STG stimulation on attention, a subset of patients with tinnitus enrolled in an rTMS clinical trial [n = 12, 9 male, mean (sd) age = 49 (15) years] underwent an attentional conflict task before and after rTMS treatment in a repeated-measures functional magnetic resonance imaging (fMRI) study.

METHODS

The Multi-Source Interference Task (MSIT), a Stroop-based visual attentional conflict fMRI task, was used to map participants' neural processing of attentional conflict prior to rTMS intervention (Baseline) and after three rTMS intervention arms: Sham, 1 Hz, and 10 Hz (four sessions per arm, 1800 pulses per session, delivered @110% of the motor threshold over the posterior superior temporal gyrus).

RESULTS

All measures of tinnitus severity (awareness, loudness, and annoyance) improved with 1 Hz rTMS intervention; however, the greatest and most robust changes were observed for ratings of tinnitus awareness (mean 16% reduction in severity from Baseline, p < 0.01). The MSIT elicited a similar pattern of neural activation among tinnitus participants at Baseline compared to an independent sample of 43 healthy comparison adults (r = 0.801, p = 0.001). Linear regression with bootstrap resampling showed that greater recruitment of bilateral prefrontal and bilateral parietal regions by MSIT at Baseline corresponded with poorer treatment response. Individual regions' activities explained 37-67% variance in participant treatment response, with left dorsolateral prefrontal cortex's MSIT activity at Baseline explaining the greatest reduction in tinnitus awareness following 1 Hz stimulation. Although left dorsolateral prefrontal cortex activity at Baseline also predicted reduction in tinnitus loudness and annoyance (∼50% variance explained), these symptoms were more strongly predicted by right middle occipital cortex (∼70% variance explained) - suggesting that the neural predictors of symptom-specific treatment outcomes may be dissociable.

CONCLUSION

These candidate neural reactivity markers of treatment response have potential clinical value in identifying tinnitus sufferers who would or would not therapeutically benefit from rTMS intervention.

Changes in functional connectivity of the amygdala during cognitive reappraisal predict symptom reduction during trauma-focused cognitive-behavioral therapy among adolescent girls with post-traumatic stress disorder

BACKGROUND

While trauma-focused cognitive-behavioral therapy (TF-CBT) is the 'gold standard' treatment for pediatric post-traumatic stress disorder (PTSD), little is known about the neural mechanisms by which TF-CBT produces clinical benefit. Here, we test the hypothesis that PTSD symptom reduction during TF-CBT among adolescent girls with PTSD is associated with changes in patterns of brain functional connectivity (FC) with the amygdala during cognitive reappraisal.

METHOD

Adolescent girls with PTSD related to physical or sexual assault (n = 34) were enrolled in TF-CBT, delivered in an approximately 12-session format, in an open trial. Before and after treatment, they were engaged in a cognitive reappraisal task, probing neural mechanisms of explicit emotion regulation, during 3 T functional magnetic resonance imaging.

RESULTS

Among adolescent girls completing TF-CBT with usable pre- and post-treatment scans (n = 20), improvements in self-reported emotion from pre- to post-treatment were positively related to improvements in PTSD symptoms. Adolescent girls with greater post-treatment symptom reduction were also able to suppress amygdala-insula FC while re-appraising, which was not evident in girls with less symptom reduction. Pre- to post-treatment changes in right amygdala to left insula FC that scaled with PTSD symptom reduction also scaled with improvements in emotion regulation.

CONCLUSIONS

These preliminary results suggest the neurocircuitry mechanisms through which TF-CBT produces clinical outcomes, providing putative brain targets for augmenting TF-CBT response.

Modes of Large-Scale Brain Network Organization during Threat Processing and Posttraumatic Stress Disorder Symptom Reduction during TF-CBT among Adolescent Girls

Posttraumatic stress disorder (PTSD) is often chronic and disabling across the lifespan. The gold standard treatment for adolescent PTSD is Trauma-Focused Cognitive-Behavioral Therapy (TF-CBT), though treatment response is variable and mediating neural mechanisms are not well understood. Here, we test whether PTSD symptom reduction during TF-CBT is associated with individual differences in large-scale brain network organization during emotion processing. Twenty adolescent girls, aged 11–16, with PTSD related to assaultive violence completed a 12-session protocol of TF-CBT. Participants completed an emotion processing task, in which neutral and fearful facial expressions were presented either overtly or covertly during 3T fMRI, before and after treatment. Analyses focused on characterizing network properties of modularity, assortativity, and global efficiency within an 824 region-of-interest brain parcellation separately during each of the task blocks using weighted functional connectivity matrices. We similarly analyzed an existing dataset of healthy adolescent girls undergoing an identical emotion processing task to characterize normative network organization. Pre-treatment individual differences in modularity, assortativity, and global efficiency during covert fear vs neutral blocks predicted PTSD symptom reduction. Patients who responded better to treatment had greater network modularity and assortativity but lesser efficiency, a pattern that closely resembled the control participants. At a group level, greater symptom reduction was associated with greater pre-to-post-treatment increases in network assortativity and modularity, but this was more pronounced among participants with less symptom improvement. The results support the hypothesis that modularized and resilient brain organization during emotion processing operate as mechanisms enabling symptom reduction during TF-CBT.

Functional independence in resting-state connectivity facilitates higher-order cognition

Growing evidence suggests that intrinsic functional connectivity (i.e. highly structured patterns of communication between brain regions during wakeful rest) may encode cognitive ability. However, the generalizability of these findings is limited by between-study differences in statistical methodology and cognitive domains evaluated. To address this barrier, we evaluated resting-state neural representations of multiple cognitive domains within a relatively large normative adult sample. Forty-four participants (mean(sd) age=31(10) years; 18 male and 26 female) completed a resting-state functional MRI scan and neuropsychological assessments spanning motor, visuospatial, language, learning, memory, attention, working memory, and executive function performance. Robust linear regression related cognitive performance to resting-state connectivity among 200 a priori determined functional regions of interest (ROIs). Only higher-order cognitions (such as learning and executive function) demonstrated significant relationships between brain function and behavior. Additionally, all significant relationships were negative - characterized by moderately positive correlations among low performers and weak to moderately negative correlations among high performers. These findings suggest that functional independence among brain regions at rest facilitates cognitive performance. Our interpretation is consistent with graph theoretic analyses which represent the brain as independent functional nodes that undergo dynamic reorganization with task demand. Future work will build upon these findings by evaluating domain-specific variance in resting-state neural representations of cognitive impairment among patient populations.

Amygdala response predicts trajectory of symptom reduction during Trauma-Focused Cognitive-Behavioral Therapy among adolescent girls with PTSD

Trauma-Focused Cognitive-Behavioral Therapy (TF-CBT) is the gold standard treatment for pediatric PTSD. Nonetheless, clinical outcomes in TF-CBT are highly variable, indicating a need to identify reliable predictors that allow forecasting treatment response. Here, we test the hypothesis that functional neuroimaging correlates of emotion processing predict PTSD symptom reduction during Trauma-Focused Cognitive-Behavioral Therapy (TF-CBT) among adolescent girls with PTSD. Thirty-four adolescent girls with PTSD related to physical or sexual assault were enrolled in TF-CBT, delivered in an approximately 12 session format, in an open trial. Prior to treatment, they were engaged in an implicit threat processing task during 3T fMRI, during which they viewed faces depicting fearful or neutral expressions. Among adolescent girls completing TF-CBT (n = 23), slopes of PTSD symptom trajectories during TF-CBT were significantly related to pre-treatment degree of bilateral amygdala activation while viewing fearful vs neutral images. Adolescents with less symptom reduction were characterized by greater amygdala activation to both threat and neutral images (i.e., less threat-safety discrimination), whereas adolescents with greater symptom reduction were characterized by amygdala activation only to threat images. These clinical outcome relationships with pre-treatment bilateral amygdala activation remained when controlling for possible confounding demographic or clinical variables (e.g., concurrent psychotropic medication, comorbid diagnoses). While limited by a lack of a control group, these preliminary results suggest that pre-treatment amygdala reactivity to fear stimuli, a component of neurocircuitry models of PTSD, positively predicts symptom reduction during TF-CBT among assaulted adolescent girls, providing support for an objective measure for forecasting treatment response in this vulnerable population.

Synthesis, binding affinity, radiolabeling, and microPET evaluation of 4-(2-substituted-4-substituted)-8-(dialkylamino)-6-methyl-1-substituted-3,4-dihydropyrido[2,3-b]pyrazin-2(1H)-ones as ligands for brain corticotropin-releasing factor type-1 (CRF1) receptors

Compounds 1-14 were synthesized in a search for high-affinity CRF1 receptor ligands that could be radiolabeled with (11)C or (18)F for use as positron emission tomography (PET) radiotracers. Derivatives of 2 were developed which contained amide N-fluoroalkyl substituents. Compounds [(18)F]24 and [(18)F]25 were found to have appropriate lipophilicities of logP7.4=2.2 but microPET imaging with [(18)F]25 demonstrated limited brain uptake.

Decoding the Traumatic Memory among Women with PTSD: Implications for Neurocircuitry Models of PTSD and Real-Time fMRI Neurofeedback

Posttraumatic Stress Disorder (PTSD) is characterized by intrusive recall of the traumatic memory. While numerous studies have investigated the neural processing mechanisms engaged during trauma memory recall in PTSD, these analyses have only focused on group-level contrasts that reveal little about the predictive validity of the identified brain regions. By contrast, a multivariate pattern analysis (MVPA) approach towards identifying the neural mechanisms engaged during trauma memory recall would entail testing whether a multivariate set of brain regions is reliably predictive of (i.e., discriminates) whether an individual is engaging in trauma or non-trauma memory recall. Here, we use a MVPA approach to test 1) whether trauma memory vs neutral memory recall can be predicted reliably using a multivariate set of brain regions among women with PTSD related to assaultive violence exposure (N=16), 2) the methodological parameters (e.g., spatial smoothing, number of memory recall repetitions, etc.) that optimize classification accuracy and reproducibility of the feature weight spatial maps, and 3) the correspondence between brain regions that discriminate trauma memory recall and the brain regions predicted by neurocircuitry models of PTSD. Cross-validation classification accuracy was significantly above chance for all methodological permutations tested; mean accuracy across participants was 76% for the methodological parameters selected as optimal for both efficiency and accuracy. Classification accuracy was significantly better for a voxel-wise approach relative to voxels within restricted regions-of-interest (ROIs); classification accuracy did not differ when using PTSD-related ROIs compared to randomly generated ROIs. ROI-based analyses suggested the reliable involvement of the left hippocampus in discriminating memory recall across participants and that the contribution of the left amygdala to the decision function was dependent upon PTSD symptom severity. These results have methodological implications for real-time fMRI neurofeedback of the trauma memory in PTSD and conceptual implications for neurocircuitry models of PTSD that attempt to explain core neural processing mechanisms mediating PTSD.

Effects of childhood maltreatment on the neural correlates of stress- and drug cue-induced cocaine craving

Childhood adversity negatively influences all stages of the addiction process and is associated with persistent alterations in neuroendocrine, autonomic and brain responses to stress. We sought to characterize the impact of childhood abuse and neglect on the neural correlates of stress- and drug cue-induced drug craving associated with cocaine addiction. Cocaine-dependent men with (n = 20) and without (n = 18) moderate to severe childhood maltreatment histories underwent functional magnetic resonance imaging during script-guided mental imagery of personalized stress, drug use and neutral experiences. Compared to the neutral script, the stress and drug use scripts activated striatal, prefrontal, posterior cingulate, temporal and cerebellar regions consistent with prior studies of induced states of stress and drug craving. For the stress script, maltreated men exhibited reduced activation of the anterior precuneus and supplementary motor area (SMA); the interaction of maltreatment severity and stress-induced craving responses predicted lesser rostral anterior cingulate cortex activation. For the drug use script, maltreated men exhibited greater left dorsolateral prefrontal cortex activation. The interaction of maltreatment severity and craving responses was associated with greater activation of the visual cortex and SMA, whereas a maltreatment-by-anxiety interaction effect included lesser ventromedial prefrontal cortex activation. The outcomes indicate an association of childhood maltreatment with a heightened appetitive anticipatory response to drug cues and a diminished engagement of regulatory and controlled action selection processes in response to stress- or drug cue-induced drug craving and anxiety responses for cocaine-dependent men. These findings provide novel insights into possible brain mechanisms by which childhood maltreatment heightens risk for relapse in drug-dependent individuals.

Synthesis, F-18 radiolabeling, and microPET evaluation of 3-(2,4-dichlorophenyl)-N-alkyl-N-fluoroalkyl-2,5-dimethylpyrazolo[1,5-a]pyrimidin-7-amines as ligands of the corticotropin-releasing factor type-1 (CRF1) receptor

A series of 3-(2,4-dichlorophenyl)-N-alkyl-N-fluoroalkyl-2,5-dimethylpyrazolo[1,5-a]pyrimidin-7-amines were synthesized and evaluated as potential positron emission tomography (PET) tracers for the corticotropin-releasing factor type-1 (CRF1) receptor. Compounds 27, 28, 29, and 30 all displayed high binding affinity (⩽1.2 nM) to the CRF1 receptor when assessed by in vitro competition binding assays at 23 °C, whereas a decrease in affinity (⩾10-fold) was observed with compound 26. The logP7.4 values of [(18)F]26-[(18)F]29 were in the range of ∼2.2-2.8 and microPET evaluation of [(18)F]26-[(18)F]29 in an anesthetized male cynomolgus monkey demonstrated brain penetrance, but specific binding was not sufficient enough to differentiate regions of high CRF1 receptor density from regions of low CRF1 receptor density. Radioactivity uptake in the skull, and sphenoid bone and/or sphenoid sinus during studies with [(18)F]28, [(18)F]28-d8, and [(18)F]29 was attributed to a combination of [(18)F]fluoride generated by metabolic defluorination of the radiotracer and binding of intact radiotracer to CRF1 receptors expressed on mast cells in the bone marrow. Uptake of [(18)F]26 and [(18)F]27 in the skull and sphenoid region was rapid but then steadily washed out which suggests that this behavior was the result of binding to CRF1 receptors expressed on mast cells in the bone marrow with no contribution from [(18)F]fluoride.

The role of childhood maltreatment in the altered trait and global expression of personality in cocaine addiction

BACKGROUND AND AIMS

Drug addictions are debilitating disorders that are highly associated with personality abnormalities. Early life stress (ELS) is a common risk factor for addiction and personality disturbances, but the relationships between ELS, addiction, and personality are poorly understood.

METHODS

Ninety-five research participants were assessed for and grouped by ELS history and cocaine dependence. NEO-FFI personality measures were compared between the groups to define ELS- and addiction-related differences in personality traits. ELS and cocaine dependence were then examined as predictors of personality trait scores. Finally, k-means clustering was used to uncover clusters of personality trait configurations within the sample. Odds of cluster membership across subject groups was then determined.

RESULTS

Trait expression differed significantly across subject groups. Cocaine-dependent subjects with a history of ELS (cocaine+/ELS+) displayed the greatest deviations in normative personality. Cocaine dependence significantly predicted four traits, while ELS predicted neuroticism and agreeableness; there was no interaction effect between ELS and cocaine dependence. The cluster analysis identified four distinct personality profiles: Open, Gregarious, Dysphoric, and Closed. Distribution of these profiles across subject groups differed significantly. Inclusion in cocaine+/ELS+, cocaine-/ELS+, and cocaine-/ELS- groups significantly increased the odds of expressing the Dysphoric, Open and Gregarious profiles, respectively.

CONCLUSIONS

Cocaine dependence and early life stress were significantly and differentially associated with altered expression of individual personality traits and their aggregation as personality profiles, suggesting that individuals who are at-risk for developing addictions due to ELS exposure may benefit from personality centered approaches as an early intervention and prevention.

Brain and behavioral evidence for altered social learning mechanisms among women with assault-related posttraumatic stress disorder

Current neurocircuitry models of PTSD focus on the neural mechanisms that mediate hypervigilance for threat and fear inhibition/extinction learning. Less focus has been directed towards explaining social deficits and heightened risk of revictimization observed among individuals with PTSD related to physical or sexual assault. The purpose of the present study was to foster more comprehensive theoretical models of PTSD by testing the hypothesis that assault-related PTSD is associated with behavioral impairments in a social trust and reciprocity task and corresponding alterations in the neural encoding of social learning mechanisms. Adult women with assault-related PTSD (n = 25) and control women (n = 15) completed a multi-trial trust game outside of the MRI scanner. A subset of these participants (15 with PTSD and 14 controls) also completed a social and non-social reinforcement learning task during 3T fMRI. Brain regions that encoded the computationally modeled parameters of value expectation, prediction error, and volatility (i.e., uncertainty) were defined and compared between groups. The PTSD group demonstrated slower learning rates during the trust game and social prediction errors had a lesser impact on subsequent investment decisions. PTSD was also associated with greater encoding of negative expected social outcomes in perigenual anterior cingulate cortex and bilateral middle frontal gyri, and greater encoding of social prediction errors in the left temporoparietal junction. These data suggest mechanisms of PTSD-related deficits in social functioning and heightened risk for re-victimization in assault victims; however, comorbidity in the PTSD group and the lack of a trauma-exposed control group temper conclusions about PTSD specifically.

Task-dependent recruitment of intrinsic brain networks reflects normative variance in cognition

BACKGROUND

Functional neuroimaging has great potential to inform clinical decisions, whether by identifying neural biomarkers of illness progression and severity, predicting therapeutic response, or selecting suitable patients for surgical interventions. Yet a persisting barrier to functional neuroimaging's clinical translation is our incomplete understanding of how normative variance in cognition, personality, and behavior shape the brain's structural and functional organization. We propose that modeling individual differences in these brain-behavior relationships is crucial for improving the accuracy of neuroimaging biomarkers for neurologic and psychiatric disorders.

METHODS

We addressed this goal by initiating the Cognitive Connectome Project, which bridges neuropsychology and neuroimaging by pairing nine cognitive domains typically assessed by clinically validated neuropsychological measures with those tapped by canonical neuroimaging tasks (motor, visuospatial perception, attention, language, memory, affective processing, decision making, working memory, and executive function). To date, we have recruited a diverse sample of 53 participants (mean [SD], age = 32 [9.7] years, 31 females).

RESULTS

As a proof of concept, we first demonstrate that our neuroimaging task battery can replicate previous findings that task performance recruits intrinsic brain networks identified during wakeful rest. We then expand upon these previous findings by showing that the extent to which these networks are recruited by task reflects individual differences in cognitive ability. Specifically, performance on the Judgment of Line Orientation task (a clinically validated measure of visuospatial perception) administered outside of the MRI scanner predicts the magnitude of task-induced activity of the dorsal visual network when performing a direct replication of this task within the MRI scanner. Other networks (such as default mode and right frontoparietal) showed task-induced changes in activity that were unrelated to task performance, suggesting these networks to not be involved in visuospatial perception.

CONCLUSION

These findings establish a methodological framework by which clinical neuropsychology and functional neuroimaging may mutually inform one another, thus enhancing the translation of functional neuroimaging into clinical decision making.

Attenuated behavioral and brain responses to trust violations among assaulted adolescent girls

Physical and sexual assault during adolescence is a potent risk factor for mental health and psychosocial problems, as well as revictimization, especially among female victims. To better understand this conferred risk, we conducted an exploratory study comparing assaulted and non-assaulted girls׳ behavioral and brain responses during a trust learning task. Adolescent girls (14 assaulted, 16 non-assaulted) performed a functional magnetic resonance imaging task that manipulated the percentages of which three different faces delivered positive and negative outcomes. Analyses focused on comparing unexpected to expected outcomes. We found that assaulted adolescent girls demonstrated less behavioral slowing in response to unexpected negative social outcomes, or trust violations (i.e., when a presumably trustworthy face delivered a negative outcome), relative to control girls. Trust violations were also associated with less activation in anterior insular and anterior cingulate regions among the assaulted group compared to the control group. Furthermore, we found that the severity of participants׳ exposure to assaultive events scaled negatively with recruitment of these regions. These preliminary results suggest that assault victims may engage differential learning processes upon unexpected negative social outcomes. These findings have implications for understanding impaired trust learning and social functioning among assault victims.

Evaluation of a corticotropin releasing hormone type 1 receptor antagonist in women with posttraumatic stress disorder: study protocol for a randomized controlled trial

BACKGROUND

Pharmacologic treatment options for posttraumatic stress disorder (PTSD) are limited in number and effectiveness. Medications currently in use to treat PTSD were originally approved based on their efficacy in other disorders, such as major depression. Substantial research in PTSD suggests that increased activity of corticotropin releasing hormone (CRH)-containing circuits are involved in the pathophysiology of the disease. This Phase II trial aims to evaluate the efficacy of a CRH type 1 receptor (CRHR1) antagonist in the treatment of PTSD.

METHODS/DESIGN

Currently untreated adult women, ages 18 to 65 years, with a primary psychiatric diagnosis of PTSD of at least 3 months' duration, are being enrolled in a parallel-group, double-blind, placebo-controlled, randomized clinical trial evaluating the efficacy and safety of GSK561679, a novel CRHR1 receptor antagonist. GSK561679 (or matching placebo) is prescribed at a fixed dose of 350 mg nightly for six weeks. The primary trial hypothesis is that GSK561679 will reduce symptoms of PTSD, as measured by the Clinician-Administered PTSD Scale (CAPS), significantly more than placebo after six weeks of treatment. Putative biological markers of PTSD which may influence treatment response are measured prior to randomization and after five weeks' exposure to the study medication, including: fear conditioning and extinction using psychophysiological measures; variants of stress-related genes and gene expression profiles; and indices of HPA axis reactivity. In addition, the impact of PTSD and treatment on neuropsychological performance and functional capacity are assessed at baseline and after the fifth week of study medication. After completion of the six-week double blind treatment period, subjects enter a one-month follow-up period to monitor for sustained response and resolution of any adverse effects.

DISCUSSION

Considerable preclinical and human research supports the hypothesis that alterations in central nervous system CRH neuronal activity are a potential mediator of PTSD symptoms. This study is the first to assess the efficacy of a specific antagonist of a CRH receptor in the treatment of PTSD. Furthermore, the biological and neuropsychological measures included in this trial will substantially inform our understanding of the mechanisms of PTSD.

TRIAL REGISTRATION

Clinicaltrials.gov Identifier: NCT01018992.Registered 6 November 2009. First patient randomized 14 January 2010.

Neural network activation during a stop-signal task discriminates cocaine-dependent from non-drug-abusing men

Cocaine dependence is defined by a loss of inhibitory control over drug-use behaviors, mirrored by measurable impairments in laboratory tasks of inhibitory control. The current study tested the hypothesis that deficits in multiple subprocesses of behavioral control are associated with reliable neural-processing alterations that define cocaine addiction. While undergoing functional magnetic resonance imaging (fMRI), 38 cocaine-dependent men and 27 healthy control men performed a stop-signal task of motor inhibition. An independent component analysis on fMRI time courses identified task-related neural networks attributed to motor, visual, cognitive and affective processes. The statistical associations of these components with five different stop-signal task conditions were selected for use in a linear discriminant analysis to define a classifier for cocaine addiction from a subsample of 26 cocaine-dependent men and 18 controls. Leave-one-out cross-validation accurately classified 89.5% (39/44; chance accuracy = 26/44 = 59.1%) of subjects with 84.6% (22/26) sensitivity and 94.4% (17/18) specificity. The remaining 12 cocaine-dependent and 9 control men formed an independent test sample, for which accuracy of the classifier was 81.9% (17/21; chance accuracy = 12/21 = 57.1%) with 75% (9/12) sensitivity and 88.9% (8/9) specificity. The cocaine addiction classification score was significantly correlated with a measure of impulsiveness as well as the duration of cocaine use for cocaine-dependent men. The results of this study support the ability of a pattern of multiple neural network alterations associated with inhibitory motor control to define a binary classifier for cocaine addiction.

Clinical correlates of attentional bias to drug cues associated with cocaine dependence

BACKGROUND AND OBJECTIVE

Preoccupation (attentional bias) related to drug-related stimuli has been consistently observed for drug-dependent persons with several studies reporting an association of the magnitude of measured attentional bias with treatment outcomes. The major goal of the present study was to determine if pre-treatment attentional bias to personal drug use reminders in an addiction Stroop task predicts relapse in treatment-seeking, cocaine-dependent subjects.

METHODS

We sought to maximize the potential of attentional bias as a marker of risk for relapse by incorporating individualized rather than generalized drug use cues to reflect the personal conditioned associations that form the incentive motivation properties of drug cues in a sample of cocaine-dependent subjects (N = 35).

RESULTS

Although a significant group Stroop interference effect was present for drug versus neutral stimuli (ie, attentional bias), the level of attentional bias for cocaine-use words was not predictive of eventual relapse in this sample (d = .56). A similar lack of prediction power was observed for a non-drug counting word Stroop task as a significant interference effect was detected but did not predict relapse outcomes (d = .40).

CONCLUSIONS AND SCIENTIFIC SIGNIFICANCE

The results of the present study do not provide clear support for the predictive value of individual variation in drug-related attentional bias to forecast probability of relapse in cocaine-dependent men.

Functional reorganization of neural networks during repeated exposure to the traumatic memory in posttraumatic stress disorder: an exploratory fMRI study

BACKGROUND

Repeated exposure to the traumatic memory (RETM) is a common component of treatments for posttraumatic stress disorder (PTSD). This treatment is based on a fear extinction model; however, the degree to which this treatment actually engages and modifies neural networks mediating fear extinction is unknown. Therefore, the purpose of the current exploratory study was to define the dynamic changes in neural processing networks while participants completed a novel adaptation of RETM.

METHOD

Participants were adult women (N = 16) with PTSD related to physical or sexual assault. Prior to scanning, participants provided written narratives of a traumatic event related to their PTSD as well as a neutral control event. RETM during fMRI consisted of 5 sequential presentations of the blocked narrative types, lasting three minutes each. Self-reported anxiety was assessed after each presentation.

RESULTS

Relative to changes in functional connectivity during the neutral control script, RETM was associated with strengthened functional connectivity of the right amygdala with the right hippocampus and right anterior insular cortex, left amygdala with the right insular cortex, medial PFC with right anterior insula, left hippocampus with striatum and dorsal cingulate cortex, and right hippocampus with striatum and orbitofrontal cortex. Greater PTSD severity generally led to less changes in functional connectivity with the right insular cortex.

CONCLUSIONS

These results provide evidence that RETM engages and modifies functional connectivity pathways with neural regions implicated in fear extinction. The results also implicate the engagement of the right insular cortex and striatum during RETM and suggest their importance in human fear extinction to trauma memories. However, comorbidity in the sample and the lack of a control group limit inferences regarding RETM with PTSD populations specifically.

Neural processing correlates of assaultive violence exposure and PTSD symptoms during implicit threat processing: a network-level analysis among adolescent girls

Assaultive violence exposure during childhood is a significant risk factor for posttraumatic stress disorder (PTSD). The purpose of the present study was to characterize the relationships of assault and PTSD severity with the organization of large-scale networks identified during emotion processing. Adolescent girls aged 12-16 with (N=15) and without (N=15) histories of assault underwent functional magnetic resonance imaging (fMRI) while engaged in a task that presented images of fearful or neutral facial expressions. Independent component analysis (ICA) identified a frontocingulate network, a frontoparietal network, and a default mode network. Assault exposure was associated with significantly greater activation of the frontocingulate network for fear versus neutral faces. Within the frontocingulate network, Posttraumatic stress disorder (PTSD) severity was associated with weakened functional connectivity between the left amygdala and the perigenual anterior cingulate. Within the frontoparietal network, assaulted girls demonstrated weakened connectivity of the premotor cortex with the right middle frontal gyrus. Within the default mode network, assault exposure and PTSD severity were associated with strengthening functional connectivity of the parahippocampus with the medial and lateral prefrontal cortex, respectively. Individual differences in functional connections within the frontocingulate network and frontoparietal network among the assaulted group were strongly associated with caregiver-rated family disengagement. These results demonstrate associations between assault and PTSD symptoms with the functional organization of large-scale frontoparietal, frontocingulate, and default mode networks during emotion processing. The relationship with caregiver-rated family disengagement suggests the impact of family support on the neural processing correlates of assault and PTSD symptoms.

Decreased brainstem and putamen SERT binding potential in depressed suicide attempters using [11C]-zient PET imaging

BACKGROUND

Deficits in serotonergic neurotransmission have been implicated in the pathogenesis of depression and suicidality. The present study utilized a novel positron-emission tomography (PET) ligand to quantitate and compare brain regional serotonin transporter (SERT) binding potential in depressed patients with a past history of suicide attempts to that of healthy comparison subjects.

METHOD

We used [(11) C]-ZIENT PET to label SERT in the serotonergic cell body rich brainstem, and forebrain projection fields. Quantitative PET emission data from 21 adults (10 healthy controls and 11 drug-free patients with major depression) was used for group comparison. SERT binding potential (BPND ) in eight MRI-based brain regions of interest (ROI) were compared in high-resolution PET images.

RESULTS

SERT binding potential was significantly decreased in the midbrain/pons (P = .029) and putamen (P = .04) of depressed patients with a past suicide attempt relative to comparison subjects. Forebrain SERT binding was also reduced in the patient sample, though these region effects did not survive a multiple comparison correction.

CONCLUSION

These results suggest that decreased availability of the brainstem and basal ganglia SERT represents a biomarker of depression and thus confirm and extend the role of dysregulation of brain serotonergic neurotransmission in the pathophysiology of depression and suicide.

Altered functional connectivity of the insular cortex across prefrontal networks in cocaine addiction

Interoception is theorized to be an important process mediating substance use disorders, and the insular cortex is recognized as a core neural region supporting interoception. The purpose of this study was to compare the integration of the insular cortex into prefrontal-related resting-state networks between individuals with cocaine dependence and healthy controls. Participants comprised 41 patients with cocaine dependence and 19 controls who underwent a resting-state 3-T functional magnetic resonance imaging scan. Individuals with cocaine dependence demonstrated altered functional connectivity of the insular cortex, predominantly the right insular cortex, with all eight prefrontal-related resting-state networks identified through Independent Component Analysis (ICA). A conjunction analysis demonstrated that the right insular cortex was the neural region with the highest number of common group differences across the networks. There was no evidence that insular cortex connectivity commonly differed between groups for non-prefrontal-related networks. Further, seed-based functional connectivity analyses extended the network analyses and indicated that cocaine dependence was associated with greater connectivity of the right insula with the dorsomedial prefrontal cortex, inferior frontal gyrus, and bilateral dorsolateral prefrontal cortex. These data support the hypothesis that cocaine dependence is related to altered functional interactions of the insular cortex with prefrontal networks. The results suggest possible neural mechanisms by which the insular cortex and interoceptive information influence cognitive control and decision-making processes presumably mediated by prefrontal networks in the cocaine dependence process.

Neuroeconomics and adolescent substance abuse: individual differences in neural networks and delay discounting

OBJECTIVE

Many adolescents with substance use problems show poor response to evidence-based treatments. Treatment outcome has been associated with individual differences in impulsive decision making as reflected by delay discounting (DD) rates (preference for immediate rewards). Adolescents with higher rates of DD were expected to show greater neural activation in brain regions mediating impulsive/habitual behavioral choices and less activation in regions mediating reflective/executive behavioral choices.

METHOD

Thirty adolescents being treated for substance abuse completed a DD task optimized to balance choices of immediate versus delayed rewards, and a control condition accounted for activation during magnitude valuation. A group independent component analysis on functional magnetic resonance imaging time courses identified neural networks engaged during DD. Network activity was correlated with individual differences in discounting rate.

RESULTS

Higher discounting rates were associated with diminished engagement of an executive attention control network involving the dorsolateral prefrontal cortex, dorsomedial prefrontal cortex, inferior parietal cortex, cingulate cortex, and precuneus. Higher discounting rates also were associated with less deactivation in a "bottom-up" reward valuation network involving the amygdala, hippocampus, insula, and ventromedial prefrontal cortex. These 2 networks were significantly negatively correlated.

CONCLUSIONS

Results support relations between competing executive and reward valuation neural networks and temporal decision making, an important, potentially modifiable risk factor relevant for the prevention and treatment of adolescent substance abuse. Clinical trial registration information-The Neuroeconomics of Behavioral Therapies for Adolescent Substance Abuse, http://clinicaltrials.gov/, NCT01093898.

Childhood maltreatment is associated with a sex-dependent functional reorganization of a brain inhibitory control network

Childhood adversity represents a major risk factor for drug addiction and other mental disorders. However, the specific mechanisms by which childhood adversity impacts human brain organization to confer greater vulnerability for negative outcomes in adulthood is largely unknown. As an impaired process in drug addiction, inhibitory control of behavior was investigated as a target of childhood maltreatment (abuse and neglect). Forty adults without Axis-I psychiatric disorders (21 females) completed a Childhood Trauma Questionnaire (CTQ) and underwent functional MRI (fMRI) while performing a stop-signal task. A group independent component analysis identified a putative brain inhibitory control network. Graph theoretical analyses and structural equation modeling investigated the impact of childhood maltreatment on the functional organization of this neural processing network. Graph theory outcomes revealed sex differences in the relationship between network functional connectivity and inhibitory control which were dependent on the severity of childhood maltreatment exposure. A network effective connectivity analysis indicated that a maltreatment dose-related negative modulation of dorsal anterior cingulate (dACC) activity by the left inferior frontal cortex (IFC) predicted better response inhibition and lesser attention deficit hyperactivity disorder (ADHD) symptoms in females, but poorer response inhibition and greater ADHD symptoms in males. Less inhibition of the right IFC by dACC in males with higher CTQ scores improved inhibitory control ability. The childhood maltreatment-related reorganization of a brain inhibitory control network provides sex-dependent mechanisms by which childhood adversity may confer greater risk for drug use and related disorders and by which adaptive brain responses protect individuals from this risk factor.

Differential functional connectivity within an emotion regulation neural network among individuals resilient and susceptible to the depressogenic effects of early life stress

BACKGROUND

Early life stress (ELS) is a significant risk factor for depression. The effects of ELS exposure on neural network organization have not been differentiated from the effect of depression. Furthermore, many individuals exposed to ELS do not develop depression, yet the network organization patterns differentiating resiliency versus susceptibility to the depressogenic effects of ELS are not clear.

METHOD

Women aged 18-44 years with either a history of ELS and no history of depression (n = 7), a history of ELS and current or past depression (n = 19), or a history of neither ELS nor depression (n = 12) underwent a resting-state 3-T functional magnetic resonance imaging (fMRI) scan. An emotion regulation brain network consisting of 21 nodes was described using graph analyses and compared between groups.

RESULTS

Group differences in network topology involved decreased global connectivity and hub-like properties for the right ventrolateral prefrontal cortex (vlPFC) and decreased local network connectivity for the dorsal anterior cingulate cortex (dACC) among resilient individuals. Decreased local connectivity and increased hub-like properties of the left amygdala, decreased hub-like properties of the dACC and decreased local connectivity of the left vlPFC were observed among susceptible individuals. Regression analyses suggested that the severity of ELS (measured by self-report) correlated negatively with global connectivity and hub-like qualities for the left dorsolateral PFC (dlPFC).

CONCLUSIONS

These preliminary results suggest functional neural connectivity patterns specific to ELS exposure and resiliency versus susceptibility to the depressogenic effects of ELS exposure.

A common TPH2 haplotype regulates the neural processing of a cognitive control demand

The monoamine neurotransmitter, serotonin, critically regulates the function of the cerebral cortex and is involved in psychiatric disorders. Tryptophan hydroxylase (TPH) is the rate-limiting enzyme in the synthesis of serotonin with the neuron-specific TPH2 isoform present exclusively in the brain and encoded by the TPH2 gene on chromosome 12q21. The haplotype structure of TPH2 was defined for 16 single-nucleotide polymorphisms (SNPs) in a healthy subject population and a haplotype block analysis confirmed the presence of a six SNP haplotype in a yin configuration that has previously been associated with risk for suicidality, depression, and anxiety disorders. Functional magnetic resonance imaging (fMRI) was used to assess the influence of TPH2 variation on brain function related to cognitive control using the Multi-Source Interference Task (MSIT). The MSIT-related blood oxygen level-dependent (BOLD) response was increased with increasing copies of the TPH2 yin haplotype for the dorsal anterior cingulate cortex (dACC), right inferior frontal cortex (IFC), and anterior striatum. A functional connectivity analysis further revealed that increasing numbers of the TPH2 yin haplotype was associated with diminished functional coupling between the dACC and the right IFC, precentral gyrus, parietal cortex and dlPFC. A moderation analysis indicated that the relationship between neural processing networks and cognitive control was significantly modulated by allelic variation for the TPH2 yin haplotype. These findings suggest that the association of risk for psychiatric disorders with a common TPH2 yin haplotype is related to the inefficient functional engagement of cortical areas involved in cognitive control and alterations in the mode of functional connectivity of dACC pathways.

A controlled trial of the adjunct use of D-cycloserine to facilitate cognitive behavioral therapy outcomes in a cocaine-dependent population

Cocaine dependence is a chronically relapsing disorder for which its predominant behavioral therapies are associated with only partial efficacy. The goal of this study was to determine if the N-methyl-d-aspartate (NMDA) glutamate receptor partial agonist and cognitive enhancer, d-cycloserine (DCS), could boost the cocaine abstinence and treatment retention goals of cognitive behavioral therapy (CBT). This study employed a placebo-controlled, randomized double-blind trial design of 44 cocaine-dependent men enrolled in a 4-week outpatient Substance Abuse Treatment Program (SATP) at the Atlanta Veteran's Administration Medical Center. Subjects received 50mg of DCS or placebo prior to four weekly sessions of a condensed version of a manual-based CBT for cocaine dependence. Cocaine abstinence and treatment retention measures represented primary outcome variables. Relative to a 12-step based treatment-as-usual, an under-dosed CBT was associated with significant improvements in drug abstinence and treatment retention at 4-weeks and for maintenance of drug abstinence after four more weeks of follow-up. The robust response to the under-dosed CBT was not enhanced by the adjunct administration of DCS at either the 4- or 8-week endpoints. This controlled clinical trial failed to demonstrate an ability of DCS to boost the relapse prevention or treatment retention goals of CBT.

Mode of effective connectivity within a putative neural network differentiates moral cognitions related to care and justice ethics

Background

Moral sensitivity refers to the interpretive awareness of moral conflict and can be justice or care oriented. Justice ethics is associated primarily with human rights and the application of moral rules, whereas care ethics is related to human needs and a situational approach involving social emotions. Among the core brain regions involved in moral issue processing are: medial prefrontal cortex, anterior (ACC) and posterior (PCC) cingulate cortex, posterior superior temporal sulcus (pSTS), insula and amygdala. This study sought to inform the long standing debate of whether care and justice moral ethics represent one or two different forms of cognition.

Methodology/Principal Findings

Model-free and model-based connectivity analysis were used to identify functional neural networks underlying care and justice ethics for a moral sensitivity task. In addition to modest differences in patterns of associated neural activity, distinct modes of functional and effective connectivity were observed for moral sensitivity for care and justice issues that were modulated by individual variation in moral ability.

Conclusions/Significance

These results support a neurobiological differentiation between care and justice ethics and suggest that human moral behavior reflects the outcome of integrating opposing rule-based, self-other perspectives, and emotional responses.

Modeling the spatial and temporal dependence in FMRI data

Functional magnetic resonance imaging (fMRI) data sets are large and characterized by complex dependence structures driven by highly sophisticated neurophysiology and aspects of the experimental designs. Typical analyses investigating task-related changes in measured brain activity use a two-stage procedure in which the first stage involves subject-specific models and the second-stage specifies group (or population) level parameters. Customarily, the first-level accounts for temporal correlations between the serial scans acquired during one scanning session. Despite accounting for these correlations, fMRI studies often include multiple sessions and temporal dependencies may persist between the corresponding estimates of mean neural activity. Further, spatial correlations between brain activity measurements in different locations are often unaccounted for in statistical modeling and estimation. We propose a two-stage, spatio-temporal, autoregressive model that simultaneously accounts for spatial dependencies between voxels within the same anatomical region and for temporal dependencies between a subject's estimates from multiple sessions. We develop an algorithm that leverages the special structure of our covariance model, enabling relatively fast and efficient estimation. Using our proposed method, we analyze fMRI data from a study of inhibitory control in cocaine addicts.

Evaluating Functional Autocorrelation within Spatially Distributed Neural Processing Networks

Data-driven statistical approaches, such as cluster analysis or independent component analysis, applied to in vivo functional neuroimaging data help to identify neural processing networks that exhibit similar task-related or restingstate patterns of activity. Ideally, the measured brain activity for voxels within such networks should exhibit high autocorrelation. An important limitation is that the algorithms do not typically quantify or statistically test the strength or nature of the within-network relatedness between voxels. To extend the results given by such data-driven analyses, we propose the use of Moran's I statistic to measure the degree of functional autocorrelation within identified neural processing networks and to evaluate the statistical significance of the observed associations. We adapt the conventional definition of Moran's I, for applicability to neuroimaging analyses, by defining the global autocorrelation index using network-based neighborhoods. Also, we compute network-specific contributions to the overall autocorrelation. We present results from a bootstrap analysis that provide empirical support for the use of our hypothesis testing framework. We illustrate our methodology using positron emission tomography (PET) data from a study that examines the neural representation of working memory among individuals with schizophrenia and functional magnetic resonance imaging (fMRI) data from a study of depression.

Compartmental modeling of 11C-HOMADAM binding to the serotonin transporter in the healthy human brain

The novel PET radioligand (11)C-N,N-dimethyl-2-(2'-amino-4'-hydroxymethylphenylthio)benzylamine ((11)C-HOMADAM) binds with high affinity and selectively to the serotonin transporter (SERT). The purpose of this study was to develop a reliable kinetic model to describe the uptake of (11)C-HOMADAM in the healthy human brain.

METHODS

Eight volunteers participated in the study; 5 of them were fitted with arterial catheters for blood sampling and all were scanned on a high-resolution research tomograph after the injection of (11)C-HOMADAM. Regional distribution volumes and binding potentials were calculated with 2- and 4-parameter arterial-input compartment models, a 3-parameter reference tissue compartment model, and the Logan graphic approach.

RESULTS

The 2-parameter arterial-input compartment model was statistically superior to the 4-parameter model and described all brain regions. Calculated binding potentials agreed well between the arterial-input model and the reference tissue model when the cerebellum was used as the reference tissue. The Logan graphic approach was not able to estimate the higher concentration of SERT in the dorsal raphe than in the midbrain.

CONCLUSION

(11)C-HOMADAM is a highly promising radioligand with high ratios of specific binding to nonspecific binding in known SERT-rich structures, such as the raphe nuclei. The 3-parameter reference tissue model approach permits a simplified quantitatively accurate method for estimating SERT binding potentials.

Synthesis, radiosynthesis, and biological evaluation of carbon-11 and fluorine-18 labeled reboxetine analogues: potential positron emission tomography radioligands for in vivo imaging of the norepinephrine transporter

Reboxetine analogues with methyl and fluoroalkyl substituents at position 2 of the phenoxy ring 1-4 were synthesized. In vitro competition binding with [(3)H]nisoxetine demonstrated that 1-4 have a high affinity for the norepinephrine transporter (NET) with K(i)'s = 1.02, 3.14, 3.68, and 0.30 nM, respectively. MicroPET imaging in rhesus monkeys showed that the relative regional distribution of [(11)C]1 and [(11)C]4 is consistent with distribution of the NET in the brain, while [(18)F]2 and [(18)F]3 showed only slight regional differentiation in brain uptake. Especially, the highest ratios of uptake of [(11)C]1 in NET-rich regions to that in caudate were obtained at 1.30-1.45 at 45 min and remained relatively constant over 85 min. Pretreatment of the monkey with the selective NET inhibitor, desipramine, decreased the specific binding for both [(11)C]1 and [(11)C]4. PET imaging in awake monkeys suggested that anesthesia influenced the binding potential of [(11)C]1 and [(11)C]4 at the NET.

Clinical milestones predict symptom remission over 6-month and choice of treatment of patients with major depressive disorder (MDD)

BACKGROUND

It is uncertain as to what short-term outcomes predict long-term treatment compliance and outcomes in patients with MDD.

AIMS

To determine what treatment milestones predict symptom remission with long-term treatment with antidepressant medication.

METHOD

Pooled analysis of four randomised, double-blind, active comparator, 6-month trials in MDD.

RESULTS

Patients received double-blind treatment with escitalopram (N=699) or a comparator (citalopram, duloxetine, or paroxetine) (N=699). Onset of effect at week 2 was correlated with response at week 8, and response at week 8 with completion of 6-month treatment. Week 8 response was associated with a greater probability of achieving later remission. Week 24 remission (MADRS>or=10) was significantly (p<0.01) higher for patients treated with escitalopram (70.7%) than for the pooled comparators (64.7%). Week 24 complete remission (MADRS<or=5) was significantly (p<0.01) higher for escitalopram (51.7%) than for the pooled comparators (45.6%). Fewer patients discontinued treatment with escitalopram (15.9%) than with the pooled comparators (23.9%) (p<0.001).

CONCLUSION

A higher probability of achieving remission is associated with responding after 8 weeks and with completing 6 months of treatment.

Synthesis, in vitro characterization, and radiolabeling of reboxetine analogs as potential PET radioligands for imaging the norepinephrine transporter

Six new (S,S)-enantiomers of reboxetine derivatives were synthesized and their binding affinities were determined via competition binding assays in cells expressing the human norepinephrine transporter (NET), serotonin transporter (SERT) or dopamine transporter (DAT). All six compounds prepared exhibit high affinity for the NET (K(i)<or=2nM) and selectivity versus the SERT and DAT. Radiolabeling methods were also developed to prepare these ligands in moderate to high radiochemical yield with high radiochemical purity via O- or S-methylation with [(11)C]CH(3)I, or O-alkylation with [(18)F]fluoroethyl brosylate or [(18)F]fluoropropyl brosylate, and their logP(7.4) was measured. These new C-11- and F-18-labeled tracers will be utilized in comparative microPET studies to evaluate their potential as PET radioligands for imaging brain NET in nonhuman primates.

Synthesis and biological evaluation of 2β,3α-(substituted phenyl)nortropanes as potential norepinephrine transporter imaging agents

A series of 2beta,3alpha-(substituted phenyl)nortropanes was synthesized and evaluated in vitro for human monoamine transporters. All compounds studied in this series exhibited nanomolar potency for the norepinephrine transporter (NET). Radiolabeling and nonhuman primate microPET brain imaging studies were performed with the most promising compound, [(11)C]1, to determine its utility as a NET imaging agent. Despite high in vitro affinity for the human NET, the high uptake of [(11)C]1 in the caudate and putamen excludes its use as an in vivo PET imaging agent for the NET.