Seawater physics and chemistry along the Med-SHIP transects in the Mediterranean Sea in 2016.

The Mediterranean Sea has been sampled irregularly by research vessels in the past, mostly by national expeditions in regional waters. To monitor the hydrographic, biogeochemical and circulation changes in the Mediterranean Sea, a systematic repeat oceanographic survey programme called Med-SHIP was recommended by the Mediterranean Science Commission (CIESM) in 2011, as part of the Global Ocean Ship-based Hydrographic Investigations Program (GO-SHIP). Med-SHIP consists of zonal and meridional surveys with different frequencies, where comprehensive physical and biogeochemical properties are measured with the highest international standards. The first zonal survey was done in 2011 and repeated in 2018. In addition, a network of meridional (and other key) hydrographic sections were designed: the first cycle of these sections was completed in 2016, with three cruises funded by the EU project EUROFLEETS2. This paper presents the physical and chemical data of the meridional and key transects in the Western and Eastern Mediterranean Sea collected during those cruises.

Emotion Regulation as a Mediator between Childhood Abuse and Neglect and Posttraumatic Stress Disorder in Women with Substance Use Disorders.

OBJECTIVE: A history of childhood abuse and neglect (CAN) is significantly associated with psychopathologies in adulthood, including comorbid posttraumatic stress disorder (PTSD) and substance use disorders (SUD). Difficulties in emotion regulation (ER) might influence the association between CAN and PTSD. The aim of this study was to examine the relationship between CAN and PTSD symptom severity in women with SUD and to investigate the mediating role of general difficulties in ER and its specific dimensions. Method: We examined 320 women, with a current diagnosis of at least subsyndromal PTSD and SUD, using self-report measures of CAN, PTSD symptom severity, and ER difficulties. We conducted both simple and multiple bootstrapping-enhanced mediation analysis to investigate whether general difficulties in ER and its specific dimensions mediate the relationship between CAN and PTSD symptom severity. Results: General difficulties in ER mediated the association between CAN and PTSD symptom severity. CAN significantly predicted adult PTSD symptom severity, directly and indirectly, through ER difficulties. Difficulties engaging in goal directed behavior when distressed was the only ER dimension, which mediated the effect of CAN on PTSD symptoms. Conclusions: Our results suggest that difficulties in ER and specifically difficulties engaging in goal directed behavior when distressed might constitute an influential factor in the relationship between CAN and PTSD symptom severity in a sample of SUD patients, and highlight the importance of targeting ER as a potential treatment focus for patients with comorbid PTSD and SUD.

Reliability of Paper-Based Routine Documentation in Psychiatric Inpatient Care and Recommendations for Further Improvement.

Background: Health services research is of increasing importance in current psychiatry. Therefore, large datasets and aggregation of data generated by electronic routine documentation due to legal, financial, or administrative purposes play an important role. However, paper-based routine documentation is still of interest. It remains relevant in less developed health care systems, in emergency settings, and in long-term retrospective and historical studies. Whereas studies examining the reliability of electronic routine documentation support the application of routine data for research purposes, our knowledge regarding reliability of paper-based routine documentation is still very sparse. Methods: Basic documentation (BADO) was completed on paper forms and digitalized manually for all inpatients of the Department of Psychiatry and Psychotherapy, University Hospital Hamburg-Eppendorf, Germany, treated within the time period from 1998 to 2006. Four hundred twelve cases of first-episode psychosis patients were chosen for comparison with clinical data from paper-based patient files. The percentage of missing information, the percentage of correct classifications, sensitivity, and positive predictive value were calculated for all applicable variables. Results: In eight cases (1.9%), a BADO form was available, but was not filled in. In 37 cases (7.0%), the patient files were lost and could not be obtained from the centralized archive. Routine data were available for all other cases in 20 (58.8%) of the examined 34 variables, and the percentage of missing data for the remaining variables ranged between 0.3% and 22.9%, with only the variables education and suicidality during treatment having more than 5% missing data. In general, the overall rate of correct classifications was high, with a median percentage of 86.4% to 99.7% for the examined variables. Sensitivity was above 75% for eight and <75% but above 50% for six of the examined 17 variables. Values for the positive predictive value were above 75% for nine and <75% but above 50% for three variables. Conclusion: In summary, paper-based routine documentation reaches acceptable reliability, but this is dependent on the chosen documentation categories and variables. Based on the present findings, paper-based routine documentation can indeed be used for quality management, organizational development, and health services research. Its limitations, however, have to be kept in mind.

[Prevalence and Phenomenology of Psychotic-Like Symptoms in Borderline Personality Disorders - Associations with Suicide Attempts and Use of Psychiatric Inpatient Treatment]. / Prävalenz und Phänomenologie fraglich psychotischer Symptome bei Borderline Persönlichkeitsstörungen.

BACKGROUND: Psychotic-like symptoms are found in a subgroup of borderline patients (BPD). Reported prevalence is heterogeneous (up to 50% affected). Investigations in Germany have not been conducted so far. Furthermore, the precise phenomenology of the psychotic symptoms and the effects on suicidal behavior and the use of inpatient psychiatric treatment are unclear. OBJECTIVES: The aim of the study was to investigate prevalence rates and phenomenology of psychotic-like symptoms. Associations between the latter and suicidality as well as the use of inpatient psychiatric treatment were examined. Further influencing factors were taking into account. METHODS: Psychotic-like symptoms were assessed with the Structured Clinical Interview-I in 95 BPD patients. To investigate the associations between psychotic-like symptoms and suicidality as well as the use of inpatient psychiatric treatment, correlation and regression analyzes were calculated, considering severity of PTSD, BPD and depression. RESULTS: 36% of the patients reported alterations of perception and 21% delusions, both multiform and long lasting. The number of suicide attempts was associated with delusions, alterations of perception and severity of PTSD, BPS, and depression. Only delusions and severity of PTSD explained together 25.8% of the variance for the prediction of the number of suicide attempts. Age of initial hospitalization showed fewer and number of hospitalizations no associations at all. DISCUSSION: Psychotic-like symptoms should not be trivialized, which may happen by using terms such as pseudo-hallucinations or transient paranoid ideas, and may be particularly associated with suicidal tendencies complicating the clinical course.

Dense water plumes modulate richness and productivity of deep sea microbes.

Growing evidence indicates that dense water formation and flow over the continental shelf is a globally relevant oceanographic process, potentially affecting microbial assemblages down to the deep ocean. However, the extent and consequences of this influence have yet to be investigated. Here it is shown that dense water propagation to the deep ocean increases the abundance of prokaryotic plankton, and stimulates carbon production and organic matter degradation rates. Dense waters spilling off the shelf modifies community composition of deep sea microbial assemblages, leading to the increased relevance of taxa likely originating from the sea surface and the seafloor. This phenomenon can be explained by a combination of factors that interplay during the dense waters propagation, such as the transport of surface microbes to the ocean floor (delivering in our site 0.1 megatons of C), the stimulation of microbial metabolism due to increased ventilation and nutrients availability, the sediment re-suspension, and the mixing with ambient waters along the path. Thus, these results highlight a hitherto unidentified role for dense currents flowing over continental shelves in influencing deep sea microbes. In light of climate projections, this process will affect significantly the microbial functioning and biogeochemical cycling of large sectors of the ocean interior.

Dissociation in patients with schizophrenia spectrum disorders: What is the role of different types of childhood adversity?

AIMS: Our study aimed to explore the effects of different types of adverse childhood experiences (e.g. domestic violence, early loss, parental dysfunction, sexual and physical abuse) as well as experiences of sexual and physical abuse in adulthood on dissociative symptoms in adult patients with schizophrenia-spectrum disorders. METHODS: 145 patients were examined for psychotic symptoms with the Positive and Negative Syndrome Scale (PANSS), for dissociative symptoms with the German version of the Dissociative Experiences Scale (DES) and for adverse experiences in childhood and adulthood with the Structured Trauma Interview (STI). RESULTS: Childhood physical abuse was reported by 32%, childhood sexual abuse by 17% of the patients. Other forms of childhood adversity were also quite common; 18% had witnessed domestic violence, 26% reported early loss, and nearly half of patients reported at least one condition potentially related to parental dysfunction. The DES total score was significantly associated with childhood sexual abuse, witnessing of domestic violence and paternal dysfunction, as well as with physical violence in adulthood. In the final regression model, reports of paternal dysfunction and sexual abuse in childhood were independently associated with adult dissociation. Variance in dissociative symptoms was mainly explained by paternal dysfunction (18%). CONCLUSION: Substantial rates of childhood adversity were found and specific associations were evident with adult dissociation amongst psychosis patients who reported sexual abuse or paternal dysfunction in childhood. Therefore, it is important that patients with schizophrenia-spectrum disorders are routinely asked about a broad range of possible adverse childhood experiences in order to provide appropriate interventions.

Perinatal mental health service provision in Switzerland and in the UK.

QUESTIONS UNDER STUDY: The epidemiology of maternal perinatal-psychiatric disorders as well as their effect on the baby is well recognised. Increasingly well researched specialised treatment methods can reduce maternal morbidity, positively affect mother-baby bonding and empower women's confidence as a mother. Here, we aimed to compare guidelines and the structure of perinatal-psychiatric service delivery in the United Kingdom and in Switzerland from the government's perspective. METHODS: Swiss cantons provided information regarding guidelines and structure of service delivery in 2000. A subsequent survey using the same questionnaire was carried out in 2007. In the UK, similar information was accessed through published reports from 2000-2012. RESULTS: Guidelines for perinatal psychiatry exist in the UK, whereas in Switzerland in 2000 none of the 26 cantons had guidelines, and in 2007 only one canton did. Joint mother-baby admissions on general psychiatric wards were offered by 92% of the Swiss cantons. In the UK, pregnant women and joint mother-baby admissions are only advised onto specialised perinatal-psychiatric units. In Switzerland, in 2007, three specialised units (max. 24 beds) were in place corresponding to 1 unit per 2.5 million people, while in the UK there were 22 mother-baby units (168 beds) in 2012 (1 unit per 2.8 million). In the UK, less than 50% of trusts provided specialised perinatal-psychiatric health care. CONCLUSIONS: The main difference between the UK and Switzerland was the absence of guidelines, regular assessment and plans for future development of perinatal psychiatry in Switzerland. There are still geographical differences in the provision of perinatal-psychiatric services in the UK.

Evidence for an agitated-aggressive syndrome predating the onset of psychosis.

BACKGROUND: Aggression and suicidality prior to the initiation of treatment are frequent phenomena in psychosis patients. Increased scores in the Brief Psychiatric Rating Scale Excited Component (BPRS-EC) have been shown to predict involuntary treatment, aggression, and suicide in first-episode psychosis (FEP) patients. However, it is unclear if an agitated-aggressive syndrome as measured with the BPRS-EC is already present in at-risk mental state (ARMS). METHODS: BPRS-EC scores from 43 ARMS patients, 50 FEP patients, and 25 healthy controls (HC) were analyzed. Multivariate analyses were performed to review if group differences were mediated by potential confounders. In addition, the association of BPRS-EC scores with clinical variables was examined. RESULTS: BPRS-EC scores were significantly different across diagnostic groups (H(2)=22.1; p<.001), and post-hoc analyses showed significantly higher BPRS-EC scores for ARMS (p=.001) and for FEP patients (p<.001) compared to HC. Differences remained significant after controlling for gender, years of education, and intelligence. No significant differences emerged between ARMS and FEP patients. BPRS-EC was significantly correlated with lower intelligence (r=-.27; p=.008), reduced level of functioning (r=-.44; p<.001), and with smoking behavior (r=.22; p=.019). CONCLUSIONS: ARMS and FEP patients in our sample had significantly higher BPRS-EC scores compared to HC. This may constitute a correlate of an agitated-aggressive syndrome and an increased risk for aggression and suicidality.

Maladaptive personality traits increase subjectively during the course of schizophrenia spectrum disorders.

We assessed both current maladaptive personality traits (MPTs) and, retrospectively, premorbid MPTs in patients with schizophrenia spectrum disorders (SSDs). This was to examine whether the patients had the impression that their personality had changed and which traits were affected. We also wanted to determine whether the perceived changes could be explained by SSD psychopathology. MPTs were assessed using the Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, diagnoses, axis II disorders, screening questionnaire and interview, integrating questions on subjective estimation of premorbid MPTs in moderately ill SSD patients. Forty-five patients were included. Premorbid MPTs were remembered as significantly less pronounced than current MPTs for the whole spectrum of personality traits (p < 0.001). Antisocial traits had worsened significantly less (p < 0.001), and borderline and obsessive-compulsive traits had worsened significantly more (both p < 0.01) than the mean increase. Associations between MPT increase and SSD psychopathology were significant for schizotypal, avoidant, and depressive traits. According to the patients' retrospective assessment, MPTs increased through onset and course of SSDs. Memory bias, depressed mood, and SSD symptoms alone could not sufficiently explain these differences. Subjective MPT increase may play a role for the patients' concept of illness, quality of life, and adherence to therapeutic interventions. It should be addressed in SSD treatment.

Subjective well-being, but not subjective mental functioning shows positive associations with neuropsychological performance in schizophrenia-spectrum disorders.

OBJECTIVE: To assess the association of subjective quality of life as measured by the Subjective Well-being under Neuroleptic Treatment questionnaire (SWN-K) with neuropsychological functioning; to address interactions with the SWN-K domain mental functioning as a measure of subjective cognitive dysfunction; and to examine the interaction of subjective well-being and psychopathology ratings. METHODS: Forty-five patients diagnosed with schizophrenia spectrum disorder (SSD) were assessed regarding subjective well-being (SWN-K), neuropsychological impairment, and psychopathology (Brief Psychiatric Rating Scale; BPRS). RESULTS: After controlling for multiple comparisons, SWN-K total score showed significant positive correlations with concentration/attention (r=.498), working memory (r=.537), verbal memory (r=.522), and global cognition (r=.459). No correlations of SWN mental functioning and neuropsychological impairment remained significant after Bonferroni correction. Correlations between SWN-K subscales and neuropsychological functioning were generally positive, indicating higher subjective well-being in patients with better neurocognition. In multivariate analyses, global cognition was a significant predictor (p=.011), accounting for 19.7% of SWN total score variance. Adding BPRS total score as predictor (p=.054) explained an additional 6.9% of SWN-K variance. Linear regression analyses with SWN-K mental functioning as dependent variable did not yield statistically significant models. CONCLUSION: Subjective well-being and objective neuropsychological functioning show only moderate associations and can be seen as largely independent parameters. In particular, subjective mental functioning cannot serve as a proxy for objective neuropsychological testing.

Psychotic symptoms in patients with borderline personality disorder: prevalence and clinical management.

PURPOSE OF REVIEW: The aim of this article is to review findings on the prevalence, phenomenology and treatment of psychotic features in borderline personality disorder (BPD), and to discuss factors that might be related to their occurrence. RECENT FINDINGS: Of patients with BPD about 20-50% report psychotic symptoms. Hallucinations can be similar to those in patients with psychotic disorders in terms of phenomenology, emotional impact, and their persistence over time. Although more research is needed on the exact nature of psychotic phenomena in patients with BPD, terms like pseudo-psychotic or quasi-psychotic are misleading and should be avoided. Childhood trauma might play an important role in the development of psychotic symptoms in patients with BPD, as in other populations. More research is necessary on the role of comorbid disorders, especially posttraumatic stress disorder (PTSD). Atypical antipsychotics seem to be beneficial in some patients; evidence on psychotherapy of psychotic symptoms is sparse. SUMMARY: Psychotic symptoms, especially hallucinations, seem to be an important feature of BPD. More research on potential mediators and adequate treatment approaches for psychotic symptoms in BPD is needed, and current diagnostic systems might require revision to emphasise psychotic symptoms.

Considering DSM-5: personality diagnostics in patients with schizophrenia spectrum disorders.

The aims of this study were to examine the prevalence of personality disorders (PD) in patients with schizophrenia spectrum disorders (SSD), to examine the interaction of axis-I and axis-II symptoms to provide an estimate on the confounding potential of SSD psychopathology in the establishment of DSM-IV PD diagnoses, and to discuss implications concerning the proposed changes in DSM-5. Patients with SSD, aged 18 to 65 years, and being at least partially remitted (PANSS total score < 75) were included. PD was examined categorically and dimensionally using the SCID-II screening questionnaire and interview, and SSD psychopathology was rated using the Positive and Negative Syndrome Scale for Schizophrenia (PANSS). Forty-five patients (31 with schizophrenia) were included in the current study. Mean age was 37.2 years, and the median duration of illness was 9.5 years. Mean PANSS total score was 42.5. The cumulative prevalence of PD in our collective was 20%, with obsessive-compulsive, antisocial, and borderline PD being the most frequent. There were no cases of cluster A PD diagnoses. In the dimensional analysis, numerous correlations of small to medium effect size emerged between maladaptive personality traits and SSD psychopathology. PD is present in a clinically relevant subgroup of SSD patients and has to be recognized in SSD treatment. Currently, it remains unclear to what extent correlations between personality traits and SSD symptoms can be explained by content overlap or co-variation of SSD psychopathology and PD traits. SSD psychopathology may bias PD diagnostics and lead to a higher percentage of categorical PD diagnoses, especially considering the proposed changes in DSM-5.

Brief Psychiatric Rating Scale - Excited Component (BPRS-EC) and neuropsychological dysfunction predict aggression, suicidality, and involuntary treatment in first-episode psychosis.

OBJECTIVE: Aggression, suicidality and involuntary treatment constitute severe clinical problems in first-episode psychosis (FEP). Although there are studies on prevalence and clinical predictors of these conditions, little is known on the influence of psychopathology and neuropsychological dysfunction. METHOD: 152 FEP inpatients were prospectively assessed using the Brief Psychiatric Rating Scale (BPRS) and a neuropsychological examination covering the domains 'processing speed', 'concentration and attention', 'executive function', 'working memory', 'verbal memory', 'verbal comprehension', 'logical reasoning', 'global cognition', and 'general intelligence'. Clinical data were collected retrospectively in a structured file audit trial. RESULTS: Patients were aged 24.5±4.9years, and 112 (74%) were male. At admission, 13 (9%) patients presented with severe aggression, and 28 (18%) with severe suicidality. 31 patients (20%) received involuntary treatment. In multivariate analyses, aggression was predicted by BPRS-Excited Component (BPRS-EC; p=.001), suicidality was predicted by BPRS-EC (p=.013) and general intelligence (p=.016), and predictors for involuntary treatment were BPRS-EC (p=.001) and neuropsychological dysfunction in the domain 'concentration and attention' (p=.016). CONCLUSION: Psychopathology and neuropsychological functioning independently predict dangerous behavior in FEP patients. Some correlations with neuropsychology (e.g., of aggression with concentration/attention) are absent in multivariate analyses and may thus constitute a proxy of psychopathological features. In addition to clinical data, BPRS-EC can be used as a predictor of dangerous behavior. Patients with severe aggression and suicidality show different patterns of neuropsychological dysfunction, indicating that suicidality should not be conceptualized as subtype of aggressive behavior.

Characteristics of the mesophotic megabenthic assemblages of the vercelli seamount (north tyrrhenian sea).

The biodiversity of the megabenthic assemblages of the mesophotic zone of a Tyrrhenian seamount (Vercelli Seamount) is described using Remotely Operated Vehicle (ROV) video imaging from 100 m depth to the top of the mount around 61 m depth. This pinnacle hosts a rich coralligenous community characterized by three different assemblages: (i) the top shows a dense covering of the kelp Laminaria rodriguezii; (ii) the southern side biocoenosis is mainly dominated by the octocorals Paramuricea clavata and Eunicella cavolinii; while (iii) the northern side of the seamount assemblage is colonized by active filter-feeding organisms such as sponges (sometimes covering 100% of the surface) with numerous colonies of the ascidian Diazona violacea, and the polychaete Sabella pavonina. This study highlights, also for a Mediterranean seamount, the potential role of an isolated rocky peak penetrating the euphotic zone, to work as an aggregating structure, hosting abundant benthic communities dominated by suspension feeders, whose distribution may vary in accordance to the geomorphology of the area and the different local hydrodynamic conditions.

NADPH oxidase Nox1 contributes to ischemic injury in experimental stroke in mice.

Reactive oxygen species (ROS) are mediators of brain injury in ischemia/reperfusion. An involvement of the NADPH oxidase Nox2 has been demonstrated. In contrast, only little is known about the contribution of the Nox1 homologue in this context. Thus, we studied the role of Nox1 in early cerebral reperfusion injury in the middle cerebral artery filament occlusion model using Nox1 knockout mice. Genetic deletion of a functional Nox1 lead to a 55% attenuation in lesion size at 24h after induction of 1h ischemia (p<0.05). This result was paralleled by a significant improvement of neurological outcome, preservation of blood-brain barrier integrity and reduced cerebral edema in Nox1(y/)(-) compared to WT mice. Interestingly, no difference in infarct size between WT and Nox1(y/)(-) was observed with an occlusion time of 2h and longer. Apoptosis rate as measured by TUNEL staining was similar between the groups. Moreover, infusion of the antioxidant TEMPOL as well as of the unspecific NO-synthase inhibitor l-NAME elicited similar changes with respect to ischemic tissue damage between WT and Nox1-deficient mice. In conclusion, Nox1 is involved in the pathophysiology of cerebral ischemia. Our data however indicate that ROS-mediated direct cellular injury is unlikely to explain the protective effect achieved by genetic deletion of the enzyme.

Diagnostic validity of ICD-10 personality dimensions: a multitrait-multimethod analysis of two self-report questionnaires and a structured interview.

BACKGROUND/AIMS: There is growing evidence that the validity of diagnostic methods for personality disorders (PD) may be insufficient. Although the ICD-10 classification system is widely used, there is little data concerning its validity for diagnosing PD. METHODS: To examine convergent and discriminant validity of ICD-10 PD, corresponding dimensions were calculated using the Inventory of Clinical Personality Accentuations (self-rating) and the International Personality Disorder Examination ICD-10 module (interview and screening questionnaire). These were administered to 42 psychiatric patients. A multitrait-multimethod analysis of the 2 self-administered questionnaires and the structured interview was conducted. RESULTS: Correspondence between methods is significant at the level of 0.01 for the schizoid, borderline, anankastic, anxious and dependent PD dimensions. The investigation of discriminant validity within and between instruments reveals several strong relationships between different PD dimensions. CONCLUSION: Convergent validity can be considered sufficient for 5 of the 9 examined PD dimensions. Non-convergence must partly be interpreted as caused by poor discriminant validity inherent in the ICD-10 classification. Conceptualization of PD as completely distinguishable entities may not reflect the clinical reality of a partial overlap between personality disorders.

Molecular characterization of a novel Staphylococcus aureus surface protein (SasC) involved in cell aggregation and biofilm accumulation.

BACKGROUND: Staphylococci belong to the most important pathogens causing implant-associated infections. Colonization of the implanted medical devices by the formation of a three-dimensional structure made of bacteria and host material called biofilm is considered the most critical factor in these infections. To form a biofilm, bacteria first attach to the surface of the medical device, and then proliferate and accumulate into multilayered cell clusters. Biofilm accumulation may be mediated by polysaccharide and protein factors. METHODOLOGY/PRINCIPAL FINDINGS: The information on Staphylococcus aureus protein factors involved in biofilm accumulation is limited, therefore, we searched the S. aureus Col genome for LPXTG-motif containing potential surface proteins and chose the so far uncharacterized S. aureus surface protein C (SasC) for further investigation. The deduced SasC sequence consists of 2186 amino acids with a molecular mass of 238 kDa and has features typical of gram-positive surface proteins, such as an N-terminal signal peptide, a C-terminal LPXTG cell wall anchorage motif, and a repeat region consisting of 17 repeats similar to the domain of unknown function 1542 (DUF1542). We heterologously expressed sasC in Staphylococcus carnosus, which led to the formation of huge cell aggregates indicative of intercellular adhesion and biofilm accumulation. To localize the domain conferring cell aggregation, we expressed two subclones of sasC encoding either the N-terminal domain including a motif that is found in various architectures (FIVAR) or 8 of the DUF1542 repeats. SasC or its N-terminal domain, but not the DUF1542 repeat region conferred production of huge cell aggregates, higher attachment to polystyrene, and enhanced biofilm formation to S. carnosus and S. aureus. SasC does not mediate binding to fibrinogen, thrombospondin-1, von Willebrand factor, or platelets as determined by flow cytometry. CONCLUSIONS/SIGNIFICANCE: Thus, SasC represents a novel S. aureus protein factor involved in cell aggregation and biofilm formation, which may play an important role in colonization during infection with this important pathogen.

Subregions of the ventral striatum show preferential coding of reward magnitude and probability.

As shown in non-human primate and human fMRI studies the probability and magnitude of anticipated rewards modulate activity in the mesolimbic dopaminergic system. Importantly, non-human primate data have revealed that single dopaminergic neurons code for both probability and magnitude of expected reward, suggesting an identical system. Using a guessing task that allowed the independent assessment of the factors probability and magnitude we were able to assess the impact of reward probability and magnitude in ventral striatal subregions in a large sample (n=98). We observed more anterior and lateral peak activation foci in the ventral striatum for reward probability and a more posterior and medial activation peak for reward magnitude, suggesting a functional segregation at the mesoscopic level. Importantly, this functional bias observed for the group average was also tested in each individual subject, allowing for proper random effects inference for the spatial dissociation. Taken together, our data point toward a functional dissociation of neuronal assemblies suggesting that certain populations of neurons are more sensitive to expected reward probability and other populations are more sensitive to reward magnitude.

Gene-gene interaction associated with neural reward sensitivity.

Reward processing depends on dopaminergic neurotransmission and is modulated by factors affecting dopamine (DA) reuptake and degradation. We used fMRI and a guessing task sensitive to reward-related activation in the prefrontal cortex and ventral striatum to study how individual variation in genes contributing to DA reuptake [DA transporter (DAT)] and degradation [catechol-o-methyltransferase (COMT)] influences reward processing. Prefrontal activity, evoked by anticipation of reward irrespective of reward probability and magnitude, was COMT genotype-dependent. Volunteers homozygous for the Met allele, associated with lower enzyme activity and presumably greater DA availability, showed larger responses compared with volunteers homozygous for the Val allele. A similar COMT effect was observed in the ventral striatum. As reported previously, the ventral striatum was also found to code gain-related expected value, i.e., the product of reward magnitude and gain probability. Individual differences in ventral striatal sensitivity for value were in part explained by an epistatic gene-gene interaction between COMT and DAT. Although most genotype combinations exhibited the expected activity increase with more likely and larger rewards, two genotype combinations (COMT Met/Met DAT 10R and COMT Val/Val 9R) were associated with blunted ventral striatal responses. In view of a consistent relationship between reduced reward sensitivity and addiction, our findings point to a potential genetic basis for vulnerability to addiction.