Long-Term Safety Analysis of a Fibrinogen Concentrate (RiaSTAP®/Haemocomplettan® P).

Fibrinogen concentrate treatment is recommended for acute bleeding episodes in adult and pediatric patients with congenital and acquired fibrinogen deficiency. Previous studies have reported a low risk of thromboembolic events (TEEs) with fibrinogen concentrate use; however, the post-treatment TEE risk remains a concern. A retrospective evaluation of RiaSTAP®/Haemocomplettan® P (CSL Behring, Marburg, Germany) post-marketing data was performed (January 1986-June 2022), complemented by a literature review of published studies. Approximately 7.45 million grams of fibrinogen concentrate was administered during the review period. Adverse drug reactions (ADRs) were reported in 337 patients, and 81 (24.0%) of these patients experienced possible TEEs, including 14/81 (17.3%) who experienced fatal outcomes. Risk factors and the administration of other coagulation products existed in most cases, providing alternative explanations. The literature review identified 52 high-ranking studies with fibrinogen concentrate across various clinical areas, including 26 randomized controlled trials. Overall, a higher number of comparative studies showed lower rates of ADRs and/or TEEs in the fibrinogen group versus the comparison group(s) compared with those that reported higher rates or no differences between groups. Post-marketing data and clinical studies demonstrate a low rate of ADRs, including TEEs, with fibrinogen concentrate treatment. These findings suggest a favorable safety profile of fibrinogen concentrate, placing it among the first-line treatments effective for managing intraoperative hemostatic bleeding.

Establishment of a Novel Short Tandem Repeat Typing Method for Exophiala dermatitidis.

The opportunistic black yeast-like fungus Exophiala dermatitidis frequently colonizes the respiratory tract of cystic fibroses (CF) patients. Additionally, it can cause superficial, systemic, and cerebral forms of phaeohyphomycoses. The objective of this study was to develop and apply a microsatellite or short tandem repeat (STR) genotyping scheme for E. dermatitidis. In total, 82 E. dermatitidis isolates from various geographic origins (environmental = 9, CF = 63, invasive isolates = 9, melanin-deficient mutant = 1) were included in this study. After next-generation sequencing of a reference strain and sequence filtering for microsatellites, six STR markers were selected and amplified in two multiplex PCR reactions. The included isolates were discriminated in a genetic cluster analysis using the Pearson algorithm to reveal the relatedness of the isolates. The E. dermatitidis isolates clustered on basis of both, their source and their origin. The invasive isolates from Asia were unrelated to isolates from CF. Nearly all environmental isolates were grouped separately from patients' isolates. The Simpson index was 0.94. In conclusion, we were able to establish a STR genotyping scheme for investigating population genomics of E. dermatitidis.

COVID-19-associated pulmonary aspergillosis in ICU patients in a German reference centre: Phenotypic and molecular characterisation of Aspergillus fumigatus isolates.

BACKGROUND: COVID-19-associated invasive pulmonary aspergillosis (CAPA) is associated with increased mortality. Cases of CAPA caused by azole-resistant Aspergillus fumigatus strains have been reported. OBJECTIVES: To analyse the twelve-month CAPA prevalence in a German tertiary care hospital and to characterise clinical A. fumigatus isolates from two German hospitals by antifungal susceptibility testing and microsatellite genotyping. PATIENTS/METHODS: Retrospective observational study in critically ill adults from intensive care units with COVID-19 from 17 February 2020 until 16 February 2021 and collection of A. fumigatus isolates from two German centres. EUCAST broth microdilution for four azole compounds and microsatellite PCR with nine markers were performed for each collected isolate (N = 27) and additional for three non-COVID A. fumigatus isolates. RESULTS: welve-month CAPA prevalence was 7.2% (30/414), and the rate of azole-resistant A. fumigatus isolates from patients with CAPA was 3.7% with detection of one TR34/L98H mutation. The microsatellite analysis revealed no major clustering of the isolates. Sequential isolates mainly showed the same genotype over time. CONCLUSIONS: Our findings demonstrate similar CAPA prevalence to other reports and a low azole-resistance rate. Genotyping of A. fumigatus showed polyclonal distribution except for sequential isolates.

Viscoelastic testing to assess the effects of rapid fibrinogen concentrate administration after cardiopulmonary bypass: insights from the REPLACE study.

Haemorrhage during and following surgery results in increased morbidity and mortality. Low plasma fibrinogen levels have been associated with increased blood loss and transfusion requirements. Fibrinogen supplementation has been shown to reduce bleeding in coagulopathic patients. This post hoc study evaluated fibrinogen repletion and pharmacokinetic data from the REPLACE study. One hundred and fifty-two adult patients undergoing elective aortic surgery requiring cardiopulmonary bypass (CPB) with defined bleeding of 60-250 g at first 5 min bleeding mass were included in the phase III trial. Patients were randomized to receive either fibrinogen concentrate (FCH) or placebo following CPB removal. Plasma fibrinogen levels and viscoelastic testing parameters (ROTEM-based FIBTEM and EXTEM assays) were measured before, during, and after study treatment administration. A mean dose of 6.3 g FCH was administered in the FCH group, with a median infusion duration of 2 min. Immediately following completion of FCH administration, a rapid increase in plasma fibrinogen levels to near baseline (median change from baseline -0.10 g/l) was seen in the FCH group but not in the placebo group (median change from baseline -1.29 g/l). FCH administration also caused an immediate increase in FIBTEM maximum clot firmness (MCF) to 23 mm and improvements in EXTEM coagulation time and clot formation time by the end of infusion. There was a strong correlation between the plasma fibrinogen level and FIBTEM MCF. Treatment with high doses of FCH with a rapid infusion time resulted in immediate recovery to baseline levels of plasma fibrinogen and viscoelastic testing parameters.

Molecular characterization of vancomycin-resistant Enterococcus faecium isolates from two German hospitals.

Introduction: Vancomycin-resistant Enterococcus faecium accounts for around 10-23% of nosocomial enterococcal infections and constitutes a relevant therapeutic problem due to its limited susceptibility to antibiotics. The resistance towards glycopeptide antibiotics is mediated by the so-called van genes. Currently, the most common resistance type in Germany is the vanB-type. Little data are available on the molecular epidemiology in Germany. Therefore, an epidemiological typing of Enterococcus faecium isolates with vanB-type resistance from two German hospitals in Essen and Nuremberg was performed. Two outbreaks and 104 sporadic cases were investigated. Methods: All 128 isolates with vanB-type resistance were collected between 2011-2012 and 2017-2018. They were characterized using multilocus sequence typing (MLST) and pulsed-field gel electrophoresis (PFGE). Results: ST 117 was the most common sequence type (ST) in both hospitals, especially since 2017. PFGE divided the isolates of this study into 68 PFGE types and showed a broad genetic diversity. Two epidemiologically assumed in-hospital outbreaks were genetically confirmed. Apart from that, in-hospital transmissions were rare events. Conclusion: The results obtained by MLST confirmed the previously described allocation of STs in Germany. PFGE showed a broad genetic diversity of vanB VRE between the two hospitals and also within each hospital. In-hospital transmissions were rare, but outbreaks did occur. Our data supports the strategy to screen and isolate patients in transmission events in order to detect monoclonality indicating a common source or hygiene mismanagement.

Fibrinogen concentrate for bleeding in patients with congenital fibrinogen deficiency: Observational study of efficacy and safety for prophylaxis and treatment.

BACKGROUND: Congenital fibrinogen deficiency (CFD) is a rare bleeding disorder characterized by reduced levels (afibrinogenemia, hypofibrinogenemia) or dysfunctional fibrinogen (dysfibrinogenemia), for which fibrinogen supplementation is the mainstay treatment. OBJECTIVES: To assess the efficacy and safety of human fibrinogen concentrate (FCH) in patients with CFD. METHODS: This was a multicenter, noninterventional, retrospective cohort study with a 12-month prospective follow-up period in the United States and Canada. Individuals with CFD who received FCH for the treatment of bleeding, perioperative hemostasis, or prophylaxis were included. Data were collected retrospectively from medical records and every 3 months during the prospective period. Hemostatic efficacy was rated by the investigators as effective or ineffective using a 4-point efficacy scale. Annualized bleeding rate (ABR) was summarized for patients who received FCH for routine prophylaxis. RESULTS: Twenty-two patients were enrolled. FCH treatment was rated effective in treating ≥97.0% of bleeding events, in the retrospective and prospective periods. FCH was effective for perioperative hemostasis in ≥97.5% of minor and major surgeries across both periods. In patients treated with FCH for routine prophylaxis, the median ABRs for the retrospective and prospective period were 1.4 and 1.3, respectively. One adverse event (AE), thrombosis of the right cephalic vein, was reported as related to FCH treatment and resolved with a short course of anticoagulant. No serious AEs related to FCH or deaths were reported. CONCLUSIONS: In patients with CFD, FCH is a well-tolerated and effective treatment to achieve hemostasis during bleeding events and surgery and associated with infrequent bleeding events when used prophylactically.

Evaluation of a commercial Loop-mediated Isothermal Amplification (LAMP) assay for rapid detection of Pneumocystis jirovecii.

BACKGROUND: Various tools are obtainable for the detection of Pneumocystis jirovecii, among them qPCR promising highest sensitivity. A novel molecular method is commercially available, the loop-mediated isothermal amplification (LAMP) assay. OBJECTIVES: We compared the performance of the LAMP eazyplex® Pneumocystis jirovecii with the RealStar Pneumocystis jirovecii PCR 1.0 qPCR. MATERIAL/METHODS: Overall, 162 lower respiratory tract specimens from 146 critically ill patients were investigated. LAMP assay and qPCR were carried out according to the manufacturer's recommendations. Positive results of the LAMP were described as time to positivity (TTP). The limit of detection (LOD) of the LAMP was analysed using 10-fold serial dilutions of a high positive P jirovecii respiratory sample. For each serial dilution, TTP of the LAMP was plotted against cycle threshold (Ct) values of the qPCR. RESULTS: The LOD of the LAMP was determined to be approximately 4 × 103 copies/mL. While the LAMP revealed 28 (17%) positive signals from 20 patients, by using qPCR 41 (25%) positive samples from 28 patients were identified. Overall agreement with qPCR was 92%. Five false-negative, one false-positive and nine invalid results were detected by the LAMP. Positive and negative predictive values were 96% each, and sensitivity and specificity were 84% and 99%, respectively. There was a low correlation between the TTP and the fungal load. CONCLUSION: The LAMP is a time-saving and easy-to-perform method. It can be used as an alternative diagnostic method. However, for quantification purposes the qPCR is still the gold standard.

Hypersensitivity pneumonitis of a bagpipe player: Fungal antigens as trigger?

Here we present a 79-year old man with chronic hypersensitivity pneumonitis probably caused by fungal contamination of a bagpipe. Several samples were taken from the patient's bagpipe. Four potential fungal antigens (Exophiala phaeomuriformis, Kwoniella europaea, Pyrenochaeta unguis-hominis and Aureobasidium melanogenum) as potential trigger of hypersensitivity pneumonitis were identified. A serum ELISA test with Exophiala phaeomuriformis indicated reactivity. Cessation of playing the bagpipe and application of glucocorticoids lead to an improvement of the patient's symptoms.

Comparison of genotyping methods for Cunninghamella bertholletiae.

BACKGROUND: Invasive fungal infections caused by filamentous fungi of the order Mucorales are serious complications in immunocompromised patients and often associated with fatal outcome. As a member of this order, Cunninghamella bertholletiae is a saprophytic fungus with naturally exhibited high minimum inhibitory concentrations against common antifungal drugs and with the potential for outbreaks in clinical settings. OBJECTIVES AND METHODS: In a proof-of-principle study, we evaluated the performance of microsatellite markers for the discrimination of thirteen C. bertholletiae isolates from various sources in comparison with a repetitive sequence-based PCR (rep-PCR) and random amplification of polymorphic DNA (RAPD). Based on the higher discriminatory power of the microsatellite PCR with five separate primer pairs (Simpson's index of 1 vs 0 [RAPD] and 0 [rep-PCR]), the novel method was applied to eight additional isolates, including four well-characterised isolates from a cluster of infections in a next step. RESULTS: In total, microsatellite PCR identified 21 separate genotypes. A probable epidemiological association of the cluster isolates could be demonstrated by microsatellite genotyping. CONCLUSION: In conclusion, our findings demonstrate the value of microsatellite PCR in genotyping Cunninghamella bertholletiae and its potential for future applications with other species of the order Mucorales.

Randomized evaluation of fibrinogen versus placebo in complex cardiovascular surgery: post hoc analysis and interpretation of phase III results.

OBJECTIVES: In a multicentre, randomized-controlled, phase III trial in complex cardiovascular surgery (Randomized Evaluation of Fibrinogen vs Placebo in Complex Cardiovascular Surgery: REPLACE), single-dose human fibrinogen concentrate (FCH) was associated with the transfusion of increased allogeneic blood products (ABPs) versus placebo. Post hoc analyses were performed to identify possible reasons for this result. METHODS: We stratified REPLACE results by adherence to the transfusion algorithm, pretreatment fibrinogen level (≤2 g/l vs >2 g/l) and whether patients were among the first 3 treated at their centre. RESULTS: Patients whose treatment was adherent with the transfusion algorithm [FCH, n = 47 (60.3%); placebo, n = 57 (77.0%); P = 0.036] received smaller quantities of ABPs than those with non-adherent treatment (P < 0.001). Among treatment-adherent patients with pretreatment plasma fibrinogen ≤2 g/l, greater reduction in 5-min bleeding mass was seen with FCH versus placebo (median -22.5 g vs -15.5 g; P = 0.071). Considering patients with the above conditions and not among the first 3 treated at their centre (FCH, n = 15; placebo, n = 22), FCH was associated with trends towards reduced transfusion of ABPs (median 2.0 vs 4.0 units; P = 0.573) and greater reduction in 5-min bleeding mass (median -21.0 g vs -9.5 g; P = 0.173). Differences from a preceding single-centre phase II study with positive outcomes included more patients with pretreatment fibrinogen >2 g/l and fewer patients undergoing thoracoabdominal aortic aneurysm repair. CONCLUSIONS: None of the patient stratifications provided a clear explanation for the lack of efficacy seen for FCH in the REPLACE trial versus the positive phase II outcomes. However, together, the 3 factors demonstrated trends favouring FCH. Less familiarity with the protocol and procedures and unavoidable differences in the study populations may explain the differences seen between the phase II study and REPLACE. CLINICAL TRIAL REGISTRATION: NCT01475669 https://clinicaltrials.gov/ct2/show/NCT01475669; EudraCT trial no: 2011-002685-20.

Au Nanoparticles as Template for Defect Formation in Memristive SrTiO3 Thin Films.

We investigated the possibility of tuning the local switching properties of memristive crystalline SrTiO 3 thin films by inserting nanoscale defect nucleation centers. For that purpose, we employed chemically-synthesized Au nanoparticles deposited on 0.5 wt%-Nb-doped SrTiO 3 single crystal substrates as a defect formation template for the subsequent growth of SrTiO 3 . We studied in detail the resulting microstructure and the local conducting and switching properties of the SrTiO 3 thin films. We revealed that the Au nanoparticles floated to the SrTiO 3 surface during growth, leaving behind a distorted thin film region in their vicinity. By employing conductive-tip atomic force microscopy, these distorted SrTiO 3 regions are identified as sites of preferential resistive switching. These findings can be attributed to the enhanced oxygen exchange reaction at the surface in these defective regions.

Detection of Leak-Induced Pipeline Vibrations Using Fiber-Optic Distributed Acoustic Sensing.

In the presented work, the potential of fiber-optic distributed acoustic sensing (DAS) for detection of small gas pipeline leaks (<1%) is investigated. Helical wrapping of the sensing fiber directly around the pipeline is used to increase the system sensitivity for detection of weak leak-induced vibrations. DAS measurements are supplemented with reference accelerometer data to facilitate analysis and interpretation of recorded vibration signals. The results reveal that a DAS system using direct fiber application approach is capable of detecting pipeline natural vibrations excited by the broadband noise generated by the leaking medium. In the performed experiment, pipeline vibration modes with acceleration magnitudes down to single µg were detected. Simple leak detection approach based on spectral integration of time-averaged DAS signals in frequency domain was proposed. Potential benefits and limitations of the presented monitoring approach were discussed with respect to its practical applicability. We demonstrated that the approached is potentially capable of detection and localization of gas pipeline leaks with leak rates down to 0.1% of the pipeline flow volume and might be of interest for monitoring of short- and medium-length gas pipelines.

Electrochemical and Electronic Charge Transport Properties of Ni-Doped LiMn2O4 Spinel Obtained from Polyol-Mediated Synthesis.

LiNi0.5Mn1.5O4 (LNMO) spinel has been extensively investigated as one of the most promising high-voltage cathode candidates for lithium-ion batteries. The electrochemical performance of LNMO, especially its rate performance, seems to be governed by its crystallographic structure, which is strongly influenced by the preparation methods. Conventionally, LNMO materials are prepared via solid-state reactions, which typically lead to microscaled particles with only limited control over the particle size and morphology. In this work, we prepared Ni-doped LiMn2O4 (LMO) spinel via the polyol method. The cycling stability and rate capability of the synthesized material are found to be comparable to the ones reported in literature. Furthermore, its electronic charge transport properties were investigated by local electrical transport measurements on individual particles by means of a nanorobotics setup in a scanning electron microscope, as well as by performing DFT calculations. We found that the scarcity of Mn3+ in the LNMO leads to a significant decrease in electronic conductivity as compared to undoped LMO, which had no obvious effect on the rate capability of the two materials. Our results suggest that the rate capability of LNMO and LMO materials is not limited by the electronic conductivity of the fully lithiated materials.

Resistive Switching of Sub-10 nm TiO2 Nanoparticle Self-Assembled Monolayers.

Resistively switching devices are promising candidates for the next generation of non-volatile data memories. Such devices are up to now fabricated mainly by means of top-down approaches that apply thin films sandwiched between electrodes. Recent works have demonstrated that resistive switching (RS) is also feasible on chemically synthesized nanoparticles (NPs) in the 50 nm range. Following this concept, we developed this approach further to the sub-10 nm range. In this work, we report RS of sub-10 nm TiO2 NPs that were self-assembled into monolayers and transferred onto metallic substrates. We electrically characterized these monolayers in regard to their RS properties by means of a nanorobotics system in a scanning electron microscope, and found features typical of bipolar resistive switching.

Echinocandin resistance and population structure of invasive Candida glabrata isolates from two university hospitals in Germany and Austria.

Echinocandin resistance in Candida glabrata is emerging and is associated with the presence of FKS mutations. In this study, we analysed the antifungal susceptibility, presence of FKS mutations and clonality of C. glabrata blood culture isolates from two hospitals in Germany and Austria. Susceptibility testing of 64 C. glabrata bloodstream isolates from two university hospitals was performed with broth microdilution method according to EUCAST. In addition, all isolates were screened for FKS mutations. Molecular fingerprinting was performed by microsatellite PCR with three separate primer pairs and semiautomated repetitive sequenced-based PCR (rep-PCR). One C. glabrata isolate from Germany (1.5%) was echinocandin resistant, with a corresponding mutation in FKS2 gene hot spot 1. The discriminatory power of microsatellite PCR was higher than that of rep-PCR (Simpson Index of 0.94 vs. 0.88); microsatellite PCR created 31 separate genotypes, whereas rep-PCR created 17. Predominant genotypes or clusters of isolates from Germany and Austria were present, with no epidemiological evidence of nosocomial transmissions. Although we found a low incidence of echinocandin resistance in C. glabrata in our settings, further surveillance projects in central Europe are warranted for monitoring future epidemiological trends. The genetic population structure of C. glabrata demonstrates overrepresented geographical clusters.

Resistive Switching of Individual, Chemically Synthesized TiO2 Nanoparticles.

Resistively switching devices are considered promising for next-generation nonvolatile random-access memories. Today, such memories are fabricated by means of "top-down approaches" applying thin films sandwiched between nanoscaled electrodes. In contrast, this work presents a "bottom-up approach" disclosing for the first time the resistive switching (RS) of individual TiO2 nanoparticles (NPs). The NPs, which have sizes of 80 and 350 nm, respectively, are obtained by wet chemical synthesis and thermally treated under oxidizing or vacuum conditions for crystallization, respectively. These NPs are deposited on a Pt/Ir bottom electrode and individual NPs are electrically characterized by means of a nanomanipulator system in situ, in a scanning electron microscope. While amorphous NPs and calcined NPs reveal no switching hysteresis, a very interesting behavior is found for the vacuum-annealed, crystalline TiO(2-x) NPs. These NPs reveal forming-free RS behavior, dominantly complementary switching (CS) and, to a small degree, bipolar switching (BS) characteristics. In contrast, similarly vacuum-annealed TiO2 thin films grown by atomic layer deposition show standard BS behavior under the same conditions. The interesting CS behavior of the TiO(2-x) NPs is attributed to the formation of a core-shell-like structure by re-oxidation of the reduced NPs as a unique feature.

Adolescents adapt more slowly than adults to varying reward contingencies.

It has been suggested that adolescents process rewards differently from adults, both cognitively and affectively. In an fMRI study we recorded brain BOLD activity of adolescents (age range = 14-15 years) and adults (age range = 20-39 years) to investigate the developmental changes in reward processing and decision-making. In a probabilistic reversal learning task, adolescents and adults adapted to changes in reward contingencies. We used a reinforcement learning model with an adaptive learning rate for each trial to model the adolescents' and adults' behavior. Results showed that adolescents possessed a shallower slope in the sigmoid curve governing the relation between expected value (the value of the expected feedback, +1 and -1 representing rewarding and punishing feedback, respectively) and probability of stay (selecting the same option as in the previous trial). Trial-by-trial change in expected values after being correct or wrong was significantly different between adolescents and adults. These values were closer to certainty for adults. Additionally, absolute value of model-derived prediction error for adolescents was significantly higher after a correct response but a punishing feedback. At the neural level, BOLD correlates of learning rate, expected value, and prediction error did not significantly differ between adolescents and adults. Nor did we see group differences in the prediction error-related BOLD signal for different trial types. Our results indicate that adults seem to behaviorally integrate punishing feedback better than adolescents in their estimation of the current state of the contingencies. On the basis of these results, we argue that adolescents made decisions with less certainty when compared with adults and speculate that adolescents acquired a less accurate knowledge of their current state, that is, of being correct or wrong.

Amygdala-function perturbations in healthy mid-adolescents with familial liability for depression.

OBJECTIVE: Functional magnetic resonance imaging (fMRI) studies have identified increased amygdala responses to negative stimuli as a risk marker of depression in adults, and as a state marker of depression in adults and adolescents. Hyperreactivity of the amygdala has been linked to negatively biased emotional processing in depression. However, no study has elucidated whether similar amygdala perturbations can be found in healthy mid-adolescents with familial liability for depression. We hypothesized that healthy 14-year-olds with relatives with depression would demonstrate increased amygdala responses to negative stimuli, as compared with their peers with no family history of mental disorders. METHOD: We investigated a community-based sample of 164 typically developing 14-year-olds without record of past or current mental disorders. Of these individuals, 28 fulfilled criteria for family history of depression, and 136 served as controls. Groups did not differ with regard to cognitive ability, depressive symptomatology, and anxiety. During fMRI they performed a perceptual discrimination task in which visual target and distractor stimuli varied systematically with regard to emotional valence. RESULTS: Both a hypothesis-driven region-of-interest analysis and a whole-brain analysis of variance revealed that negative distractors elicited greater amygdala activation in adolescents with a family history of depression compared to controls. Amygdala responses also differed during the processing of negative target stimuli, but effects were reversed. CONCLUSION: Our study demonstrates that familial liability for depression is associated with correlates of negatively biased emotional processing in healthy adolescents. Amygdala perturbations during the processing of negative stimuli might reflect an early and subtle risk marker for depression.

Interindividual differences in mid-adolescents in error monitoring and post-error adjustment.

A number of studies have concluded that cognitive control is not fully established until late adolescence. The precise differences in brain function between adults and adolescents with respect to cognitive control, however, remain unclear. To address this issue, we conducted a study in which 185 adolescents (mean age (SD) 14.6 (0.3) years) and 28 adults (mean age (SD) 25.2 (6.3) years) performed a single task that included both a stimulus-response (S-R) interference component and a task-switching component. Behavioural responses (i.e. reaction time, RT; error rate, ER) and brain activity during correct, error and post-error trials, detected by functional magnetic resonance imaging (fMRI), were measured. Behaviourally, RT and ER were significantly higher in incongruent than in congruent trials and in switch than in repeat trials. The two groups did not differ in RT during correct trials, but adolescents had a significantly higher ER than adults. In line with similar RTs, brain responses during correct trials did not differ between groups, indicating that adolescents and adults engage the same cognitive control network to successfully overcome S-R interference or task switches. Interestingly, adolescents with stronger brain activation in the bilateral insulae during error trials and in fronto-parietal regions of the cognitive control network during post-error trials did have lower ERs. This indicates that those mid-adolescents who commit fewer errors are better at monitoring their performance, and after detecting errors are more capable of flexibly allocating further cognitive control resources. Although we did not detect a convincing neural correlate of the observed behavioural differences between adolescents and adults, the revealed interindividual differences in adolescents might at least in part be due to brain development.

Differential representation of feedback and decision in adolescents and adults.

It is widely accepted that brain maturation from adolescence to adulthood contributes to substantial behavioural changes. Despite this, however, knowledge of the precise mechanisms is still sparse. We used fMRI to investigate developmental differences between healthy adolescents (age range 14-15) and adults (age range 20-39) in feedback-related decision making using a probabilistic reversal learning task. Conventionally groups are compared based on continuous values of blood oxygen level dependent (BOLD) percentage signal change. In contrast, we transformed these values into discrete states and used the pattern of these states to compare groups. We focused our analysis on anterior cingulate cortex (ACC), ventral striatum (VS) and ventromedial prefrontal cortex (vmPFC) as their functions have been shown to be critical in feedback related decision making. Discretisation of continuous BOLD values revealed differential patterns of activity as compared to conventional statistical methods. Results showed differential representation of feedback and decision in ACC and vmPFC between adolescents and adults but no difference in VS. We argue that the pattern of activity of ACC, vmPFC and VS in adolescents resulted in several drawbacks in decision making such as redundant and imprecise representation of decision and subsequently poorer performance in terms of the number of system changes (change of contingencies). This method can be effectively used to infer group differences from within-group analysis rather than studying the differences by direct between-group comparisons.