Development of stochastically reconstructed 3D porous media micromodels using additive manufacturing: numerical and experimental validation

We propose an integrated methodology for the design and fabrication of 3D micromodels that are suitable for the pore-scale study of transport processes in macroporous materials. The micromodels, that bear the pore-scale characteristics of sandstone, such as porosity, mean pore size, etc, are designed following a stochastic reconstruction algorithm that allows for fine-tuning the porosity and the correlation length of the spatial distribution of the solid material. We then construct a series of 3D micromodels at very fine resolution (i.e. 16 μ m) using a state-of-the-art 3D printing infrastructure, specifically a ProJet MJP3600 3D printer, that utilizes the Material Jetting technology. Within the technical constraints of the 3D printer resolution, the fabricated micromodels represent scaled-up replicas of natural sandstones, that are suitable for the study of the scaling between the permeability, the porosity and the mean pore size. The REV- and pore-scale characteristics of the resulting physical micromodels are recovered using a combination of X-ray micro-CT and microfluidic studies. The experimental results are then compared with single-phase flow simulations at pore-scale and geostatistic models in order to determine the effects of the design parameters on the intrinsic permeability and the spatial correlation of the velocity profile. Our numerical and experimental measurements reveal an excellent match between the properties of the designed and fabricated 3D domains, thus demonstrating the robustness of the proposed methodology for the construction of 3D micromodels with fine-tuned and well-controlled pore-scale characteristics. Furthermore, a pore-scale numerical study over a wider range of 3D digital domain realizations reveals a very good match of the measured permeabilities with the predictions of the Kozeny-Carman formulation based on a single control parameter, k 0 , that is found to have a practically constant value for porosities ϕ ≥ 0.2 . This, in turn, enables us to customize the sample size to meet REV constraints, including enlarging pore morphology while considering the Reynolds number. It is also found that at lower porosities there is a significant increase in the fraction of the non-percolating pores, thus leading to different k 0 , as the porosity approaches a numerically determined critical porosity value, ϕ c , where the domain is no longer percolating.

Exploring Carbonate Rock Dissolution Dynamics and the Influence of Rock Mineralogy in CO2 Injection

Understanding geochemical dissolution in porous materials is crucial, especially in applications such as geological CO2 storage. Accurate estimation of reaction rates enhances predictive modeling in geochemical-flow simulations. Fractured porous media, with distinct transport time scales in fractures and the matrix, raise questions about fracture-matrix interface dissolution rates compared to bulk dissolution rate and the scale-dependency of reaction rate averaging. Our investigation delves into these factors, studying the impact of flow rate and mineralogy on interface dissolution patterns. By injecting carbonated water into carbonate rock samples containing a central channel (mimicking fracture hydrodynamics), our study utilized μCT X-ray imaging at 3.3 μm spatial resolution to estimate the reaction rate and capture the change in pore morphology. Results revealed dissolution rates significantly lower (up to 4 orders of magnitude) than batch experiments. Flow rate notably influenced fracture profiles, causing uneven enlargement at low rates and uniform widening at higher ones. Ankerite presence led to a dissolution-altered layer on the fracture surface, showing high permeability and porosity without greatly affecting the dissolution rate, unlike clay-rich carbonates. This research sheds light on controlling factors influencing dissolution in subsurface environments, critical for accurate modeling in diverse applications.

Exploring real-time functional magnetic resonance imaging neurofeedback in adolescents with disruptive behavior disorder and callous unemotional traits

INTRODUCTION

Adolescents with increased callous unemotional traits (CU traits) in the context of disruptive behavior disorder (DBD) show a persistent pattern of antisocial behavior with shallow affect and a lack of empathy or remorse. The amygdala and insula as regions commonly associated with emotion processing, empathy and arousal are implicated in DBD with high CU traits. While behavioral therapies for DBD provide significant but small effects, individualized treatments targeting the implicated brain regions are missing.

METHODS

In this explorative randomized controlled trial we randomly assigned twenty-seven adolescents with DBD to individualized real-time functional magnetic resonance neurofeedback (rtfMRI-NF) or behavioral treatment as usual (TAU). Visual feedback of either amygdala or insula activity was provided during rtfMRI-NF by gauges and included a simple and concurrent video run plus a transfer run. A linear mixed model (LMM) was applied to determine improvement of self-regulation. Specificity was assessed by correlating individual self-regulation improvement with clinical outcomes.

RESULTS

The rtfMRI-NF (n = 11) and TAU (n = 10) completers showed comparable and significant clinical improvement indicating neither superiority nor inferiority of rtfMRI-NF. The exploratory LMM revealed successful learning of self-regulation along the course of training for participants who received feedback from the amygdala. A significant exploratory correlation between individual target region activity in the simple run and clinical improvement was found for one dimension of DBD.

CONCLUSIONS

This exploratory study demonstrated feasibility and suggests clinical efficacy of individualized rtfMRI-NF comparable to active TAU for adolescents with DBD and increased CU traits. Further studies are needed to confirm efficacy, specificity and to clarify underlying learning mechanisms.

X-ray 3D imaging-based microunderstanding of granular mixtures: Stiffness enhancement by adding small fractions of soft particles

This research focuses on performing ultrasound propagation measurements and micro-X-ray computed tomography (µXRCT) imaging on prestressed granular packings prepared with biphasic mixtures of monodisperse glass and rubber particles at different compositions/fractions. Ultrasound experiments employing piezoelectric transducers, mounted in an oedometric cell (complementing earlier triaxial cell experiments), are used to excite and detect longitudinal ultrasound waves through randomly prepared mixtures of monodisperse stiff/soft particles. While the fraction of the soft particles is increasing linearly from zero, the effective macroscopic stiffness of the granular packings transits nonlinearly and nonmonotonically toward the soft limit, remarkably via an interesting stiffer regime for small rubber fractions between 0.1 ≲ ν ≲ 0.2. The contact network of dense packings, as accessed from µXRCT, plays a key role in understanding this phenomenon, considering the structure of the network, the chain length, the grain contacts, and the particle coordination. While the maximum stiffness is due to surprisingly shortened chains, the sudden drop in elastic stiffness of the mixture packings, at ν ≈ 0.4, is associated with chains of particles that include both glass and rubber particles (soft chains); for ν ≲ 0.3, the dominant chains include only glass particles (hard chains). At the drop, ν ≈ 0.4, the coordination number of glass and rubber networks is approximately four and three, respectively, i.e., neither of the networks are jammed, and the chains need to include particles from another species to propagate information.

Practical challenges of continuous real-time functional magnetic resonance imaging neurofeedback with multiband accelerated echo-planar imaging and short repetition times

Continuous real-time functional magnetic resonance imaging (fMRI) neurofeedback is gaining increasing scientific attention in clinical neuroscience and may benefit from the short repetition times of modern multiband echoplanar imaging sequences. However, minimizing feedback delay can result in technical challenges. Here, we report a technical problem we experienced during continuous fMRI neurofeedback with multiband echoplanar imaging and short repetition times. We identify the possible origins of this problem, describe our current interim solution and provide openly available workflows and code to other researchers in case they wish to use a similar approach.

Cerebral processing of sharp mechanical pain measured with arterial spin labeling

INTRODUCTION

Arterial spin labeling (ASL) is a functional neuroimaging technique that has been frequently used to investigate acute pain states. A major advantage of ASL as opposed to blood-oxygen-level-dependent functional neuroimaging is its applicability for low-frequency designs. As such, ASL represents an interesting option for studies in which repeating an experimental event would reduce its ecological validity. Whereas most ASL pain studies so far have used thermal stimuli, to our knowledge, no ASL study so far has investigated pain responses to sharp mechanical pain.

METHODS

As a proof of concept, we investigated whether ASL has the sensitivity to detect brain activation within core areas of the nociceptive network in healthy controls following a single stimulation block based on 96 s of mechanical painful stimulation using a blunt blade.

RESULTS

We found significant increases in perfusion across many regions of the nociceptive network such as primary and secondary somatosensory cortices, premotor cortex, posterior insula, inferior parietal cortex, parietal operculum, temporal gyrus, temporo-occipital lobe, putamen, and the cerebellum. Contrary to our hypothesis, we did not find any significant increase within ACC, thalamus, or PFC. Moreover, we were able to detect a significant positive correlation between pain intensity ratings and pain-induced perfusion increase in the posterior insula.

CONCLUSION

We demonstrate that ASL is suited to investigate acute pain in a single event paradigm, although to detect activation within some regions of the nociceptive network, the sensitivity of our paradigm seemed to be limited. Regarding the posterior insula, our paradigm was sensitive enough to detect a correlation between pain intensity ratings and pain-induced perfusion increase. Previous experimental pain studies have proposed that intensity coding in this region may be restricted to thermal stimulation. Our result demonstrates that the posterior insula encodes intensity information for mechanical stimuli as well.

Nonuniqueness of hydrodynamic dispersion revealed using fast 4D synchrotron x-ray imaging

Experimental and field studies reported a significant discrepancy between the cleanup and contamination time scales, while its cause is not yet addressed. Using high-resolution fast synchrotron x-ray computed tomography, we characterized the solute transport in a fully saturated sand packing for both contamination and cleanup processes at similar hydrodynamic conditions. The discrepancy in the time scales has been demonstrated by the nonuniqueness of hydrodynamic dispersion coefficient versus injection rate (Péclet number). Observations show that in the mixed advection-diffusion regime, the hydrodynamic dispersion coefficient of cleanup is significantly larger than that of the contamination process. This nonuniqueness has been attributed to the concentration-dependent diffusion coefficient during the cocurrent and countercurrent advection and diffusion, present in contamination and cleanup processes. The new findings enhance our fundamental understanding of transport processes and improve our capability to estimate the transport time scales of chemicals or pollution in geological and engineering systems.

An open, modular, and flexible micro X-ray computed tomography system for research

In this paper, a modular and open micro X-ray Computed Tomography (μXRCT) system is presented, which was set up during the last years at the Institute of Applied Mechanics (CE) of the University of Stuttgart and earlier at the Institute of Computational Engineering of Ruhr-University Bochum. The system is characterized by its intrinsic flexibility resulting from the modular and open design on each level and the opportunity to implement advanced experimental in situ setups. On the one hand, the presented work is intended to support researchers interested in setting up an experimental XRCT system for the microstructural characterization of materials. On the other hand, it aims to support scientists confronted with the decision to set up a system on their own or to buy a commercial scanner. In addition to the presentation of the various hardware components and the applied modular software concept, the technical opportunities of the open and modular hard- and software design are demonstrated by implementing a simple and reliable method for the compensation of bad detector pixels to enhance the raw data quality of the projections. A detailed investigation of the performance of the presented system with regard to the achievable spatial resolution is presented. XRCT datasets of three different applications are finally shown and discussed, demonstrating the wide scope of options of the presented system.

Improved emotion regulation after neurofeedback: A single-arm trial in patients with borderline personality disorder

Real-time functional magnetic resonance imaging (fMRI) neurofeedback training of amygdala hemodynamic activity directly targets a neurobiological mechanism, which contributes to emotion regulation problems in borderline personality disorder (BPD). However, it remains unknown which outcome measures can assess changes in emotion regulation and affective instability, associated with amygdala downregulation in a clinical trial. The current study directly addresses this question. Twenty-four female patients with a DSM-IV BPD diagnosis underwent four runs of amygdala neurofeedback. Before and after the training, as well as at a six-weeks follow-up assessment, participants completed measures of emotion dysregulation and affective instability at diverse levels of analysis (verbal report, clinical interview, ecological momentary assessment, emotion-modulated startle, heart rate variability, and fMRI). Participants were able to downregulate their amygdala blood oxygen-dependent (BOLD) response with neurofeedback. There was a decrease of BPD symptoms as assessed with the Zanarini rating scale for BPD (ZAN-BPD) and a decrease in emotion-modulated startle to negative pictures after training. Further explorative analyses suggest that patients indicated less affective instability, as seen by lower hour-to-hour variability in negative affect and inner tension in daily life. If replicated by an independent study, our results imply changes in emotion regulation and affective instability for several systems levels, including behavior and verbal report. Conclusions are limited due to the lack of a control group. A randomized controlled trial (RCT) will be needed to confirm effectiveness of the training.

Resting-state brain network features associated with short-term skill learning ability in humans and the influence of N-methyl-d-aspartate receptor antagonism

Graph theoretical functional magnetic resonance imaging (fMRI) studies have demonstrated that brain networks reorganize significantly during motor skill acquisition, yet the associations between motor learning ability, brain network features, and the underlying biological mechanisms remain unclear. In the current study, we applied a visually guided sequential pinch force learning task and graph theoretical analyses to investigate the associations between short-term motor learning ability and resting-state brain network metrics in 60 healthy subjects. We further probed the test-retest reliability (n = 26) and potential effects of the N-methyl-d-aspartate (NMDA) antagonist ketamine (n = 19) in independent healthy volunteers. Our results show that the improvement of motor performance after short-term training was positively correlated with small-worldness (p = 0.032) and global efficiency (p = 0.025), whereas negatively correlated with characteristic path length (p = 0.014) and transitivity (p = 0.025). In addition, using network-based statistics (NBS), we identified a learning ability–associated (p = 0.037) and ketamine-susceptible (p = 0.027) cerebellar-cortical network with fair to good reliability (intraclass correlation coefficient [ICC] > 0.7) and higher functional connectivity in better learners. Our results provide new evidence for the association of intrinsic brain network features with motor learning and suggest a role of NMDA-related glutamatergic processes in learning-associated subnetworks.

Learning a new motor skill prompts immediate reconfigurations of distributed brain networks followed by adaptive changes in intrinsic brain circuits related to synaptic plasticity. Here, we identify global brain network properties and a cerebellar-cortical functional subnetwork that are both significantly associated with motor learning ability in a previously trained visuomotor task in humans. We further show that the associated functional subnetwork connectivity but not the global brain network properties are susceptible to ketamine. Our findings suggest a distinct functional role for learning-related global versus local network metrics and support the idea of a preferential susceptibility of learning-associated subnetworks to N-methyl-d-aspartate antagonist and plasticity-related consolidation effects.

[Degenerative cervical spine diseases: fusion vs. total disc replacement : What can be done when?]

Motion preserving surgery within the cervical spine may be performed by special implants, for example, c spine disc prosthesis or total disc replacement (cTDR), or by simple decompression of the cervical nerve roots. However, also fusion surgery may be performed with good results. Here, we summarize indications as well as contraindications for motion preserving techniques and indications for fusion surgery. cTDR is indicated in special cases of soft disc herniation, especially in younger individuals without signs of myelopathy. Posterior decompression may be used as an alternative, especially if anterior surgery is not possible. If degeneration is severe, in the presence of kyphosis, severe canal encroachment, instability, and in cases of myelopathy, cervical spine fusion seems to be the better way.

Monitoring and control of amygdala neurofeedback involves distributed information processing in the human brain

Brain-computer interfaces provide conscious access to neural activity by means of brain-derived feedback ("neurofeedback"). An individual's abilities to monitor and control feedback are two necessary processes for effective neurofeedback therapy, yet their underlying functional neuroanatomy is still being debated. In this study, healthy subjects received visual feedback from their amygdala response to negative pictures. Activation and functional connectivity were analyzed to disentangle the role of brain regions in different processes. Feedback monitoring was mapped to the thalamus, ventromedial prefrontal cortex (vmPFC), ventral striatum (VS), and rostral PFC. The VS responded to feedback corresponding to instructions while rPFC activity differentiated between conditions and predicted amygdala regulation. Control involved the lateral PFC, anterior cingulate, and insula. Monitoring and control activity overlapped in the VS and thalamus. Extending current neural models of neurofeedback, this study introduces monitoring and control of feedback as anatomically dissociated processes, and suggests their important role in voluntary neuromodulation.

Fronto-Striatal Glutamate in Autism Spectrum Disorder and Obsessive Compulsive Disorder

This corrects the article DOI: 10.1038/npp.2016.260.

State-Dependent Cross-Brain Information Flow in Borderline Personality Disorder

IMPORTANCE

Although borderline personality disorder (BPD)-one of the most common, burdensome, and costly psychiatric conditions-is characterized by repeated interpersonal conflict and instable relationships, the neurobiological mechanism of social interactive deficits remains poorly understood.

OBJECTIVE

To apply recent advancements in the investigation of 2-person human social interaction to investigate interaction difficulties among people with BPD.

DESIGN, SETTING, AND PARTICIPANTS

Cross-brain information flow in BPD was examined from May 25, 2012, to December 4, 2015, in pairs of participants studied in 2 linked functional magnetic resonance imaging scanners in a university setting. Participants performed a joint attention task. Each pair included a healthy control individual (HC) and either a patient currently fulfilling DSM-IV criteria for BPD (cBPD) (n = 23), a patient in remission for 2 years or more (rBPD) (n = 17), or a second HC (n = 20). Groups were matched for age and educational level.

MAIN OUTCOMES AND MEASURES

A measure of cross-brain neural coupling was computed following previously published work to indicate synchronized flow between right temporoparietal junction networks (previously shown to host neural coupling abilities in health). This measure is derived from an independent component analysis contrasting the time courses of components between pairs of truly interacting participants compared with bootstrapped control pairs.

RESULTS

In the sample including 23 women with cBPD (mean [SD] age, 26.8 [5.7] years), 17 women with rBPD (mean [SD] age, 28.5 [4.3] years), and 80 HCs (mean [SD] age, 24.0 [3.4] years]) investigated as dyads, neural coupling was found to be associated with disorder state (η2 = 0.17; P = .007): while HC-HC pairs showed synchronized neural responses, cBPD-HC pairs exhibited significantly lower neural coupling just above permutation-based data levels (η2 = 0.16; P = .009). No difference was found between neural coupling in rBPD-HC and HC-HC pairs. The neural coupling in patients was significantly associated with childhood adversity (T = 2.3; P = .03).

CONCLUSIONS AND RELEVANCE

This study provides a neural correlate for a core diagnostic and clinical feature of BPD. Results indicate that hyperscanning may deliver state-associated biomarkers for clinical social neuroscience. In addition, at least some neural deficits of BPD may be more reversible than is currently assumed for personality disorders.

Neurofeedback Training Effects on Inhibitory Brain Activation in ADHD: A Matter of Learning?

Neurofeedback training (NF) is a promising non-pharmacological treatment for ADHD that has been associated with improvement of attention-deficit/hyperactivity disorder (ADHD)-related symptoms as well as changes in electrophysiological measures. However, the functional localization of neural changes following NF compared to an active control condition, and of successful learning during training (considered to be the critical mechanism for improvement), remains largely unstudied. Children with ADHD (N=16, mean age: 11.81, SD: 1.47) were randomly assigned to either slow cortical potential (SCP, n=8) based NF or biofeedback control training (electromyogram feedback, n=8) and performed a combined Flanker/NoGo task pre- and post-training. Effects of NF, compared to the active control, and of learning in transfer trials (approximating successful transfer to everyday life) were examined with respect to clinical outcome and functional magnetic resonance imaging (fMRI) changes during inhibitory control. After 20 sessions of training, children in the NF group presented reduced ADHD symptoms and increased activation in areas associated with inhibitory control compared to baseline. Subjects who were successful learners (n=9) also showed increased activation in an extensive inhibitory network irrespective of the type of training. Activation increased in an extensive inhibitory network following NF training, and following successful learning through NF and control biofeedback. Although this study was only powered to detect large effects and clearly requires replication in larger samples, the results suggest a crucial role for learning effects in biofeedback trainings.

Reduced amygdala responsivity during conditioning to trauma-related stimuli in posttraumatic stress disorder

Exaggerated conditioned fear responses and impaired extinction along with amygdala overactivation have been observed in posttraumatic stress disorder (PTSD). These fear responses might be triggered by cues related to the trauma through higher-order conditioning, where reminders of the trauma may serve as unconditioned stimuli (US) and could maintain the fear response. We compared arousal, valence, and US expectancy ratings and BOLD brain responses using fMRI in 14 traumatized persons with PTSD and 14 without PTSD (NPTSD) and 13 matched healthy controls (HC) in a differential aversive conditioning paradigm. The US were trauma-specific pictures for the PTSD and NPTSD group and equally aversive and arousing for the HC; the conditioned stimuli (CS) were graphic displays. During conditioning, the PTSD patients compared to the NPTSD and HC indicated higher arousal to the conditioned stimulus that was paired with the trauma picture (CS+) compared to the unpaired (CS-), increased dissociation during acquisition and extinction, and failure to extinguish the CS/US-association compared to NPTSD. During early and late acquisition, the PTSD patients showed a significantly lower amygdala activation to CS+ versus CS- and a negative interaction between activation in the amygdala and dorsolateral prefrontal cortex (PFC), while NPTSD and HC displayed a negative interaction between amygdala and medial PFC. These findings suggest maladaptive anticipatory coping with trauma-related stimuli in patients with PTSD, indicated by enhanced conditioning, with related abnormal amygdala reactivity and connectivity, and delayed extinction.

Real-time functional magnetic resonance imaging neurofeedback can reduce striatal cue-reactivity to alcohol stimuli

It has been shown that in alcoholic patients, alcohol-related cues produce increased activation of reward-related brain regions like the ventral striatum (VS), which has been proposed as neurobiological basis of craving. Modulating this activation might be a promising option in the treatment of alcohol addiction. One approach might be real-time functional magnetic resonance imaging neurofeedback (rtfMRI NF). This study was set up to implement and evaluate a rtfMRI approach in a group of non-addicted heavy social drinkers. Thirty-eight heavy drinking students were assigned to a real feedback group (rFB, n = 13), a yoke feedback group (yFB, n = 13) and a passive control group (noFB, n = 12). After conducting a reward task as functional localizer to identify ventral striatal regions, the participants viewed alcohol cues during three NF training blocks in a 3 T MRI scanner. The rFB group received feedback from their own and the yFB from another participants' VS. The noFB group received no feedback. The rFB and the yFB groups were instructed to downregulate the displayed activation. Activation of the VS and prefrontal control regions was compared between the groups. We found significant downregulation of striatal regions specifically in the rFB group. While the rFB and the yFB groups showed significant activation of prefrontal regions during feedback, this activation was only correlated to the reduction of striatal activation in the rFB group. We conclude that rtfMRI NF is a suitable method to reduce striatal activation to alcohol cues. It might be a promising supplement to the treatment of alcoholic patients.

The Influence of Micronutrients on Cognitive Function and Performance

There has been much media speculation (often sensationalist and conflicting) regarding the potential influence of micronutrients on cognitive function and performance. Our aim was to identify the micronutrients specifically implicated in cognitive function and to review the literature to identify original sources underlying the media coverage. Literature searches were carried out to identify recent clinical trials, reviews, editorials and meetings describing the biochemical and physiological role of individual micronutrients. No attempt was made to grade the evidence. The searches confirmed that the water-soluble vitamins (B group and C), together with the minerals, calcium, magnesium and zinc, are most relevant to cognitive performance. Clinical evidence revealed that marginal deficiencies of one or more of these micronutrients are not uncommon, even in the developed countries, and that such deficiencies may affect cognitive performance, especially in vulnerable groups such as the elderly and those individuals who are exposed to occupational pressures and a stressful lifestyle.

Alterations of amygdala-prefrontal connectivity with real-time fMRI neurofeedback in BPD patients

With the use of real-time functional magnetic resonance imaging neurofeedback (NF), amygdala activitiy can be visualized in real time. In this study, continuous amygdala NF was provided to patients with borderline personality disorder (BPD) with the instruction to down-regulate. During four sessions of NF training, patients viewed aversive pictures and received feedback from a thermometer display, which showed the amygdala blood oxygenation level-dependent signal. Conditions of regulation and viewing without regulation were presented. Each session started with a resting-state scan and was followed by a transfer run without NF. Amygdala regulation, task-related and resting-state functional brain connectivity were analyzed. Self-ratings of dissociation and difficulty in emotion regulation were collected. BPD patients down-regulated right amygdala activation but there were no improvements over time. Task-related amygdala-ventromedial prefrontal cortex connectivity was altered across the four sessions, with an increased connectivity when regulating vs viewing pictures. Resting-state amygdala-lateral prefrontal cortex connectivity was altered and dissociation, as well as scores for 'lack of emotional awareness', decreased with training. Results demonstrated that amygdala NF may improve healthy brain connectivity, as well as emotion regulation. A randomized-controlled trial is needed to investigate whether amygdala NF is instrumental for improving neural regulation and emotion regulation in BPD patients.

Longitudinal Mapping of Gyral and Sulcal Patterns of Cortical Thickness and Brain Volume Regain during Early Alcohol Abstinence

We explored brain volume recovery in terms of cortical thickness (CTh; gyral, sulcal pattern) and surface area (SA), as well as subcortical volume recovery in the first 2 weeks of abstinence in 49 alcohol-dependent patients (ADPs). A widespread reduction of CTh in ADPs at day 1 of abstinence compared to healthy controls, with more pronounced differences in sulci relative to gyri was found. After 2 weeks of abstinence, partial recovery to varying degrees of CTh loss in ADPs was observed for several regions. The longitudinal CTh changes were greater in sulci than in gyri of affected regions. No longitudinal change in SAs and subcortical volumes was found. Alterations of CTh contribute to brain volume loss in alcoholism and recovery during early abstinence. Sulci seem to be more vulnerable to excessive alcohol consumption and to drive abstinence-induced volume recovery. During the initial 2 weeks of abstinence no subcortical volume regain was observed. Either the time span was too short or the lower subcortical volume could represent a predisposing trait marker.

Information flow between interacting human brains: Identification, validation, and relationship to social expertise

Social interactions are fundamental for human behavior, but the quantification of their neural underpinnings remains challenging. Here, we used hyperscanning functional MRI (fMRI) to study information flow between brains of human dyads during real-time social interaction in a joint attention paradigm. In a hardware setup enabling immersive audiovisual interaction of subjects in linked fMRI scanners, we characterize cross-brain connectivity components that are unique to interacting individuals, identifying information flow between the sender's and receiver's temporoparietal junction. We replicate these findings in an independent sample and validate our methods by demonstrating that cross-brain connectivity relates to a key real-world measure of social behavior. Together, our findings support a central role of human-specific cortical areas in the brain dynamics of dyadic interactions and provide an approach for the noninvasive examination of the neural basis of healthy and disturbed human social behavior with minimal a priori assumptions.

Down-regulation of amygdala activation with real-time fMRI neurofeedback in a healthy female sample

Psychiatric conditions of emotion dysregulation are often characterized by difficulties in regulating the activity of limbic regions such as the amygdala. Real-time functional magnetic resonance imaging (rt-fMRI) allows to feedback brain activation and opens the possibility to establish a neurofeedback (NF) training of amygdala activation, e.g., for subjects suffering from emotion dysregulation. As a first step, we investigated whether feedback of the amygdala response to aversive scenes can improve down-regulation of amygdala activation. One group of healthy female participants received amygdala feedback (N = 16) and a control group was presented with feedback from a control region located in the basal ganglia [N(sum) = 32]. Subjects completed a one-session rt-fMRI-NF training where they viewed aversive pictures and received continuous visual feedback on brain activation (REGULATE condition). In a control condition, subjects were advised to respond naturally to aversive pictures (VIEW), and a neutral condition served as the non-affective control (NEUTRAL). In an adjacent run, subjects were presented with aversive pictures without feedback to test for transfer effects of learning. In a region of interest (ROI) analysis, the VIEW and the REGULATE conditions were contrasted to estimate brain regulation success. The ROI analysis was complemented by an exploratory analysis of activations at the whole-brain level. Both groups showed down-regulation of the amygdala response during training. Feedback from the amygdala but not from the control region was associated with down-regulation of the right amygdala in the transfer test. The whole-brain analysis did not detect significant group interactions. Results of the group whole-brain analyses are discussed. We present a proof-of-concept study using rt-fMRI-NF for amygdala down-regulation in the presence of aversive scenes. Results are in line with a potential benefit of NF training for amygdala regulation.

Transient and sustained BOLD signal time courses affect the detection of emotion-related brain activation in fMRI

A tremendous amount of effort has been dedicated to unravel the functional neuroanatomy of the processing and regulation of emotion, resulting in a well-described picture of limbic, para-limbic and prefrontal regions involved. Studies applying functional magnetic resonance imaging (fMRI) often use the block-wise presentation of stimuli with affective content, and conventionally model brain activation as a function of stimulus or task duration. However, there is increasing evidence that regional brain responses may not always translate to task duration and rather show stimulus onset-related transient time courses. We assume that brain regions showing transient responses cannot be detected in block designs using a conventional fMRI analysis approach. At the same time, the probability of detecting these regions with conventional analyses may be increased when shorter stimulus timing or a more intense stimulation during a block is used. In a within-subject fMRI study, we presented aversive pictures to 20 healthy subjects and investigated the effect of experimental design (i.e. event-related and block design) on the detection of brain activation in limbic and para-limbic regions of interest of emotion processing. In addition to conventional modeling of sustained activation during blocks of stimulus presentation, we included a second response function into the general linear model (GLM), suited to detect transient time courses at block onset. In the conventional analysis, several regions like the amygdala, thalamus and periaqueductal gray were activated irrespective of design. However, we found a positive BOLD response in the anterior insula (AI) in event-related but not in block-design analyses. GLM analyses suggest that this difference may result from a transient response pattern which cannot be captured by the conventional fMRI analysis approach. Our results indicate that regions with a transient response profile like the AI can be missed in block designs if analyses do not account for transient responses. This may bias conclusions from empirical reports and meta-analyses towards an underestimation of these regions and their role in emotion and emotion regulation. The cognitive processes underlying differential time courses are discussed.

Treatment of traumatized victims of war and torture: a randomized controlled comparison of narrative exposure therapy and stress inoculation training

BACKGROUND

The aim of the present randomized controlled trial was to compare the outcome of 2 active treatments for posttraumatic stress disorder (PTSD) as a consequence of war and torture: narrative exposure therapy (NET) and stress inoculation training (SIT).

METHODS

Twenty-eight PTSD patients who had experienced war and torture, most of them asylum seekers, received 10 treatment sessions of either NET or SIT at the Outpatient Clinic for Refugees, University of Konstanz, Germany. Posttests were carried out 4 weeks after treatment, and follow-up tests were performed 6 months and 1 year after treatment. The main outcome measure was the PTSD severity score according to the Clinician-Administered PTSD Scale (CAPS) at each time point.

RESULTS

A significant reduction in PTSD severity was found for NET, but not for SIT. A symptom reduction in the NET group occurred between pretest and the 6-month follow-up examination, the effect size being d = 1.42 (for SIT: d = 0.12), and between pretest and the 1-year follow-up, the effect size being d = 1.59 (for SIT: d = 0.19). The rates and scores of major depression and other comorbid disorders did not decrease significantly over time in either of the 2 treatment groups.

CONCLUSIONS

The results indicate that exposure treatments like NET lead to a significant PTSD symptom reduction even in severely traumatized refugees and asylum seekers.

Expression of platelet-bound stromal cell-derived factor-1 in patients with non-valvular atrial fibrillation and ischemic heart disease

AIMS

Blood cell infiltration and inflammation are involved in atrial remodelling during atrial fibrillation (AF) although the exact mechanisms of inflammatory cell recruitment remain poorly understood. Platelet-bound stromal cell-derived factor-1 (SDF-1) is increased in cases of ischemic myocardium and regulates recruitment of CXCR4(+) cells on the vascular wall. Whether platelet-bound SDF-1 expression is differentially influenced by non-valvular paroxysmal or permanent atrial fibrillation (AF) in patients with stable angina pectoris (SAP) or acute coronary syndrome (ACS) has not been reported so far.

METHODS AND RESULTS

A total of 1291 consecutive patients with coronary artery disease (CAD) undergoing coronary angiography were recruited. Among the patients with SAP, platelet-bound-SDF-1 is increased in patients with paroxysmal AF compared with SR or to persistent/permanent AF (P < 0.05 for both). Platelet-bound SDF-1 correlated with plasma SDF-1 (r = 0.488, P = 0.013) in patients with AF and ACS, which was more pronounced among patients with persistent AF (r = 0.842, P = 0.009). Plasma SDF-1 was increased in persistent/permanent AF compared with SR. Patients with ACS presented with enhanced platelet-bound-SDF-1 compared with SAP. Interestingly, among patients with ACS, patients with paroxysmal or persistent/permanent AF presented with an impaired platelet-bound SDF-1 expression compared with patients with SR.

CONCLUSIONS

Differential expression of platelet-bound and plasma SDF-1 was observed in patients with AF compared with SR which may be involved in progenitor cell mobilization and inflammatory cell recruitment in patients with AF and ischemic heart disease. Further in vivo studies are required to elucidate the role of SDF-1 in atrial remodeling and the atrial fibrillation course.

Transgenerational impact of intimate partner violence on methylation in the promoter of the glucocorticoid receptor

Prenatal exposure to maternal stress can have lifelong implications for psychological function, such as behavioral problems and even the development of mental illness. Previous research suggests that this is due to transgenerational epigenetic programming of genes operating in the hypothalamic-pituitary-adrenal axis, such as the glucocorticoid receptor (GR). However, it is not known whether intrauterine exposure to maternal stress affects the epigenetic state of these genes beyond infancy. Here, we analyze the methylation status of the GR gene in mothers and their children, at 10-19 years after birth. We combine these data with a retrospective evaluation of maternal exposure to intimate partner violence (IPV). Methylation of the mother's GR gene was not affected by IPV. For the first time, we show that methylation status of the GR gene of adolescent children is influenced by their mother's experience of IPV during pregnancy. As these sustained epigenetic modifications are established in utero, we consider this to be a plausible mechanism by which prenatal stress may program adult psychosocial function.

Men who have sex with men: estimating the size of at-risk populations in London primary care trusts

The objective of this study was to estimate local at-risk populations of men who have sex with men (MSM) in London primary care trusts (PCTs) to inform the commissioning of targeted health interventions. Estimated population size and prevalence of diagnosed HIV in MSM in all of London were calculated using data from the British National Survey of Sexual Attitudes and Lifestyles (NATSAL), Greater London Authority population estimates and the annual survey of diagnosed MSM (Survey of Prevalent HIV Infections Diagnosed [SOPHID]). Estimated MSM population sizes at the PCT level were calculated using un-weighted and SOPHID-weighted methods and methods discussed. Four-fifths of MSM with diagnosed HIV infection in Greater London lived in inner London. Estimated population size of MSM 16-44 years in inner London was 66,000; estimated overall prevalence of diagnosed HIV infection among MSM was 9.5%. Our models show substantial variation at the PCT level between the two methods. Using the SOPHID-weighted method MSM account for up to 16% of the male population in some London PCTs, compared with as low as 3% in others. We provide a novel method of estimating at-risk MSM populations living in inner London PCTs indicating that proportions of MSM vary widely between PCTs. Significant proportions of MSM among the resident populations in several PCTs warrant inclusion of MSM health needs in core PCT prevention and service programming. In light of data source limitations further validation studies are needed.

Correlation of glutamate levels in the anterior cingulate cortex with self-reported impulsivity in patients with borderline personality disorder and healthy controls

CONTEXT

Dysfunction and deficits in the structure of the anterior cingulate cortex have been reported in borderline personality disorder (BPD). To our knowledge, there is only 1 published study to date investigating anterior cingulate cortex metabolism in subjects with BPD and co-occurring attention-deficit/hyperactivity disorder using proton magnetic resonance spectroscopy. Impulsivity is a key feature of BPD and can be related to anterior cingulate cortex function.

OBJECTIVE

To investigate whether anterior cingulate cortex metabolism may be altered in BPD and correlates with BPD pathology.

DESIGN

Cross-sectional proton magnetic resonance spectroscopy study.

SETTING

Department of Psychosomatic Medicine and Psychotherapy, Central Institute of Mental Health, Mannheim, Germany.

PARTICIPANTS AND PATIENTS

Thirty unmedicated female subjects meeting DSM-IV criteria for BPD and 31 age-matched healthy female control participants.

MAIN OUTCOME MEASURES

Neurometabolite concentrations in the anterior cingulate cortex and correlation of glutamate levels with self-reported measures of impulsivity and severity of borderline symptoms.

RESULTS

Significantly higher levels of glutamate in the anterior cingulate cortex were found in subjects with BPD as compared with healthy controls. A positive correlation between glutamate concentration and the Barratt Impulsiveness Scale total score as well as between glutamate concentration and the subscore for cognitive impulsivity were observed irrespective of diagnosis. We also found a positive correlation between glutamate concentrations and dissociation as well as between glutamate concentration and subscores of the Borderline Symptom List in the patient group.

CONCLUSIONS

Our results support the hypothesis that higher glutamate concentration in the anterior cingulate cortex is associated with both severity of BPD symptoms and subjective impulsivity ratings, the latter independent of BPD. Further studies should confirm the association between enhanced glutamate concentration in the anterior cingulate cortex and behavioral measures of impulsivity.

Acute D2 receptor blockade induces rapid, reversible remodeling in human cortical-striatal circuits

Structural remodeling has been observed in the human brain over periods of weeks to months, but the molecular mechanisms governing this process remain incompletely characterized. Using multimodal pharmaco-neuroimaging, we found that acute D2 receptor blockade induced reversible striatal volume changes and structural-functional decoupling in motor circuits within hours; these alterations predicted acute extrapyramidal motor symptoms with high precision. Our findings suggest a role for D2 receptors in short-term neural plasticity and identify a potential biomarker for neuroleptic side effects in humans.

Pathological amygdala activation during working memory performance: Evidence for a pathophysiological trait marker in bipolar affective disorder

Recent evidence suggests that deficits of working memory may be a promising neurocognitive endophenotype of bipolar affective disorder. However, little is known about the neurobiological correlates of these deficits. The aim of this study was to determine possible pathophysiological trait markers of bipolar disorder in neural circuits involved in working memory. Functional magnetic resonance imaging was performed in 18 euthymic bipolar patients and 18 matched healthy volunteers using two circuit-specific experimental tasks established by prior systematic neuroimaging studies of working memory. Both euthymic bipolar patients and healthy controls showed working memory-related brain activations that were highly consistent with findings from previous comparable neuroimaging studies in healthy subjects. While these patterns of brain activation were completely preserved in the bipolar patients, only the patients exhibited activation of the right amygdala during the articulatory rehearsal task. In the same task, functional activation in right frontal and intraparietal cortex and in the right cerebellum was significantly enhanced in the patients. These findings indicate that the right amygdala is pathologically activated in euthymic bipolar patients during performance of a circuit-specific working memory task (articulatory rehearsal). This pathophysiological abnormality appears to be a trait marker in bipolar disorders that can be observed even in the euthymic state and that seems to be largely independent of task performance and medication.

Prefrontal-temporal gray matter deficits in bipolar disorder patients with persecutory delusions

OBJECTIVES

Although brain structural deficits have been repeatedly associated with bipolar disorder (BD), inconsistency in morphometric results has been a feature of neuroimaging studies. We hypothesize that this discrepancy is related to the heterogeneity of BD, and examine the question of whether or not more homogeneous clinical subgroups display a more coherent pattern of morphometric abnormalities.

METHODS

In a case-control design, we examined differences in gray matter (GM), white matter (WM) and cerebrospinal fluid (CSF) concentration in 42 BD patients and 42 healthy matched controls using optimized voxel-based morphometry (VBM). Subgroup analyses of patients with a lifetime history of psychotic symptoms (BDP, n=30) and patients with mood-incongruent psychotic symptoms in the form of persecutory delusions (BDPD, n=15) were performed to accord with previous genetic findings.

RESULTS

Analysis of the total BD sample was largely inconclusive, but the BDPD patient subgroup displayed a widespread pattern of significant decreases in GM concentration in the dorsolateral prefrontal (DLPFC), temporal and cingulate cortices, and a significant CSF increase in the adjacent outer ventricular sulci. Comparison of BDPD patients versus BD and BDP patients without persecutory delusions revealed a significant GM decrease in the left DLPFC for the former group.

CONCLUSIONS

BDPD show pronounced structural abnormalities of the prefrontal and temporal lobes which are similar to the deficits previously reported for schizophrenia (SCZ). Our findings suggest that stratification based solely on psychotic symptoms is insufficient for the differentiation of BD into biologically meaningful subgroups, but also question the pathophysiological validity of the dichotomy in classification between schizophrenia and BD.

Script-driven imagery of self-injurious behavior in patients with borderline personality disorder: a pilot FMRI study

OBJECTIVE

Self-injurious behavior (SIB) is one of the most distinctive features of borderline personality disorder (BPD) and related to impulsivity and emotional dysregulation.

METHOD

Female patients with BPD (n = 11) and healthy controls (n = 10) underwent functional magnetic resonance imaging while listening to a standardized script describing an act of self-injury. Experimental sections of the script were contrasted to the neutral baseline section and group-specific brain activities were compared.

RESULTS

While imagining the reactions to a situation triggering SIB, patients with BPD showed significantly less activation in the orbitofrontal cortex compared with controls. Furthermore, only patients with BPD showed increased activity in the dorsolateral prefrontal cortex during this section and a decrease in the mid-cingulate while imagining the self-injurious act itself.

CONCLUSION

This pattern of activation preliminary suggests an association with diminished emotion regulation, impulse control as well as with response selection and reappraisal during the imagination of SIB.

Overlapping neural correlates of reading emotionally positive and negative adjectives

Comparison of positive and negative naturally read adjectives to neutral adjectives yielded an overlapping higher BOLD response in the occipital and the orbitofrontal cortex (gyrus rectus). Superior medial frontal gyrus and posterior cingulate gyrus showed higher BOLD response to negative adjectives and inferior frontal gyrus to positive adjectives. The overlap of activated regions and lack of pronounced distinct regions supports the assumption that the processing of negative and positive words mainly takes place in overlapping brain regions.

Pair production in laser fields oscillating in space and time

The production of electron-positron pairs from vacuum by counterpropagating laser beams of linear polarization is calculated. In contrast with the usual approximate approach, the spatial dependence and magnetic component of the laser field are taken into account. We show that the latter strongly affects the creation process at high laser frequency: the production probability is reduced, the kinematics is fundamentally modified, the resonant Rabi-oscillation pattern is distorted, and the resonance positions are shifted, multiplied, and split.

Setting up an enhanced surveillance of newly acquired hepatitis C infection in men who have sex with men: a pilot in London and South East region of England

Preliminary findings suggest ongoing HCV transmission among MSM infected with human immunodeficiency virus (HIV) and that enhanced surveillance for newly acquired HCV in MSM is feasible.

Setting up an enhanced surveillance of newly acquired hepatitis C infection in men who have sex with men: a pilot in London and South East region of England

We describe the implementation of an enhanced surveillance pilot for newly acquired hepatitis C (HCV) in men who have sex with men (MSM) in London and the South East region of England. Preliminary findings suggest ongoing HCV transmission among MSM infected with human immunodeficiency virus (HIV) and that enhanced surveillance for newly acquired HCV in MSM is feasible.