Factual and counterfactual learning in major adolescent depressive disorder, evidence from an instrumental learning study.

BACKGROUND: The incidence of adolescent depressive disorder is globally skyrocketing in recent decades, albeit the causes and the decision deficits depression incurs has yet to be well-examined. With an instrumental learning task, the aim of the current study is to investigate the extent to which learning behavior deviates from that observed in healthy adolescent controls and track the underlying mechanistic channel for such a deviation. METHODS: We recruited a group of adolescents with major depression and age-matched healthy control subjects to carry out the learning task with either gain or loss outcome and applied a reinforcement learning model that dissociates valence (positive v. negative) of reward prediction error and selection (chosen v. unchosen). RESULTS: The results demonstrated that adolescent depressive patients performed significantly less well than the control group. Learning rates suggested that the optimistic bias that overall characterizes healthy adolescent subjects was absent for the depressive adolescent patients. Moreover, depressed adolescents exhibited an increased pessimistic bias for the counterfactual outcome. Lastly, individual difference analysis suggested that these observed biases, which significantly deviated from that observed in normal controls, were linked with the severity of depressive symoptoms as measured by HAMD scores. CONCLUSIONS: By leveraging an incentivized instrumental learning task with computational modeling within a reinforcement learning framework, the current study reveals a mechanistic decision-making deficit in adolescent depressive disorder. These findings, which have implications for the identification of behavioral markers in depression, could support the clinical evaluation, including both diagnosis and prognosis of this disorder.

Correction: AVPR1a and SLC6A4 Gene Polymorphisms Are Associated with Creative Dance Performance.

[This corrects the article DOI: 10.1371/journal.pgen.0010042.].

Serotonin and early life stress interact to shape brain architecture and anxious avoidant behavior - a TPH2 imaging genetics approach.

BACKGROUND: Early life stress has been associated with emotional dysregulations and altered architecture of limbic-prefrontal brain systems engaged in emotional processing. Serotonin regulates both, developmental and experience-dependent neuroplasticity in these circuits. Central serotonergic biosynthesis rates are regulated by Tryptophan hydroxylase 2 (TPH2) and transgenic animal models suggest that TPH2-gene associated differences in serotonergic signaling mediate the impact of aversive early life experiences on a phenotype characterized by anxious avoidance. METHODS: The present study employed an imaging genetics approach that capitalized on individual differences in a TPH2 polymorphism (703G/T; rs4570625) to determine whether differences in serotonergic signaling modulate the effects of early life stress on brain structure and function and punishment sensitivity in humans (n = 252). RESULTS: Higher maltreatment exposure before the age of 16 was associated with increased gray matter volumes in a circuitry spanning thalamic-limbic-prefrontal regions and decreased intrinsic communication in limbic-prefrontal circuits selectively in TT carriers. In an independent replication sample, associations between higher early life stress and increased frontal volumes in TT carriers were confirmed. On the phenotype level, the genotype moderated the association between higher early life stress exposure and higher punishment sensitivity. In TT carriers, the association between higher early life stress exposure and punishment sensitivity was critically mediated by increased thalamic-limbic-prefrontal volumes. CONCLUSIONS: The present findings suggest that early life stress shapes the neural organization of the limbic-prefrontal circuits in interaction with individual variations in the TPH2 gene to promote a phenotype characterized by facilitated threat avoidance, thus promoting early adaptation to an adverse environment.

Genome-wide association study of Parkinson's disease in East Asians.

Genome-wide association studies (GWAS) on Parkinson's disease (PD) have mostly been done in Europeans and Japanese. No study has been done in Han Chinese, which make up nearly a fifth of the world population. We conducted the first Han Chinese GWAS analysing a total of 22,729 subjects (5,125 PD cases and 17,604 controls) from Singapore, Hong Kong, Malaysia, Korea, mainland China and Taiwan. We performed imputation, merging and logistic regression analyses of 2,402,394 SNPs passing quality control filters in 779 PD cases, 13,227 controls, adjusted for the first three principal components. 90 SNPs with association P < 10-4 were validated in 9 additional sample collections and the results were combined using fixed-effects inverse-variance meta-analysis. We observed strong associations reaching genome-wide significance at SNCA, LRRK2 and MCCC1, confirming their important roles in both European and Asian PD. We also identified significant (P < 0.05) associations at 5 loci (DLG2, SIPA1L2, STK39, VPS13C and RIT2), and observed the same direction of associations at 9 other loci including BST1 and PARK16. Allelic heterogeneity was observed at LRRK2 while European risk SNPs at 6 other loci including MAPT and GBA-SYT11 were non-polymorphic or very rare in our cohort. Overall, we replicate associations at SNCA, LRRK2, MCCC1 and 14 other European PD loci but did not identify Asian-specific loci with large effects (OR > 1.45) on PD risk. Our results also demonstrate some differences in the genetic contribution to PD between Europeans and Asians. Further pan-ethnic meta-analysis with European GWAS cohorts may unravel new PD loci.

Delay discounting, genetic sensitivity, and leukocyte telomere length.

In a graying world, there is an increasing interest in correlates of aging, especially those found in early life. Leukocyte telomere length (LTL) is an emerging marker of aging at the cellular level, but little is known regarding its link with poor decision making that often entails being overly impatient. Here we investigate the relationship between LTL and the degree of impatience, which is measured in the laboratory using an incentivized delay discounting task. In a sample of 1,158 Han Chinese undergraduates, we observe that steeper delay discounting, indexing higher degree of impatience, is negatively associated with LTL. The relationship is robust after controlling for health-related variables, as well as risk attitude-another important determinant of decision making. LTL in females is more sensitive to impatience than in males. We then asked if genes possibly modulate the effect of impatient behavior on LTL. The oxytocin receptor gene (OXTR) polymorphism rs53576, which has figured prominently in investigations of social cognition and psychological resources, and the estrogen receptor ß gene (ESR2) polymorphism rs2978381, one of two gonadal sex hormone genes, significantly mitigate the negative effect of impatience on cellular aging in females. The current results contribute to understanding the relationship between preferences in decision making, particularly impatience, and cellular aging, for the first time to our knowledge. Notably, oxytocin and estrogen receptor polymorphisms temper accelerated cellular aging in young females who tend to make impatient choices.

Genetic variation in CD38 and breastfeeding experience interact to impact infants' attention to social eye cues.

Attending to emotional information conveyed by the eyes is an important social skill in humans. The current study examined this skill in early development by measuring attention to eyes while viewing emotional faces in 7-mo-old infants. In particular, we investigated individual differences in infant attention to eyes in the context of genetic variation (CD38 rs3796863 polymorphism) and experiential variation (exclusive breastfeeding duration) related to the oxytocin system. Our results revealed that, whereas infants at this age show a robust fear bias (increased attention to fearful eyes), their attention to angry and happy eyes varies as a function of exclusive breastfeeding experience and genetic variation in CD38. Specifically, extended exclusive breastfeeding duration selectively enhanced looking preference to happy eyes and decreased looking to angry eyes. Importantly, however, this interaction was impacted by CD38 variation, such that only the looking preferences of infants homozygous for the C allele of rs3796863 were affected by breastfeeding experience. This genotype has been associated with reduced release of oxytocin and higher rates of autism. In contrast, infants with the CA/AA genotype showed similar looking preferences regardless of breastfeeding exposure. Thus, differences in the sensitivity to emotional eyes may be linked to an interaction between the endogenous (CD38) and exogenous (breastfeeding) availability of oxytocin. These findings underline the importance of maternal care and the oxytocin system in contributing to the early development of responding to social eye cues.

Dissociable contribution of prefrontal and striatal dopaminergic genes to learning in economic games.

Game theory describes strategic interactions where success of players' actions depends on those of coplayers. In humans, substantial progress has been made at the neural level in characterizing the dopaminergic and frontostriatal mechanisms mediating such behavior. Here we combined computational modeling of strategic learning with a pathway approach to characterize association of strategic behavior with variations in the dopamine pathway. Specifically, using gene-set analysis, we systematically examined contribution of different dopamine genes to variation in a multistrategy competitive game captured by (i) the degree players anticipate and respond to actions of others (belief learning) and (ii) the speed with which such adaptations take place (learning rate). We found that variation in genes that primarily regulate prefrontal dopamine clearance--catechol-O-methyl transferase (COMT) and two isoforms of monoamine oxidase--modulated degree of belief learning across individuals. In contrast, we did not find significant association for other genes in the dopamine pathway. Furthermore, variation in genes that primarily regulate striatal dopamine function--dopamine transporter and D2 receptors--was significantly associated with the learning rate. We found that this was also the case with COMT, but not for other dopaminergic genes. Together, these findings highlight dissociable roles of frontostriatal systems in strategic learning and support the notion that genetic variation, organized along specific pathways, forms an important source of variation in complex phenotypes such as strategic behavior.

Genetic risk of extranodal natural killer T-cell lymphoma: a genome-wide association study.

BACKGROUND: Extranodal natural killer T-cell lymphoma (NKTCL), nasal type, is a rare and aggressive malignancy that occurs predominantly in Asian and Latin American populations. Although Epstein-Barr virus infection is a known risk factor, other risk factors and the pathogenesis of NKTCL are not well understood. We aimed to identify common genetic variants affecting individual risk of NKTCL. METHODS: We did a genome-wide association study of 189 patients with extranodal NKTCL, nasal type (WHO classification criteria; cases) and 957 controls from Guangdong province, southern China. We validated our findings in four independent case-control series, including 75 cases from Guangdong province and 296 controls from Hong Kong, 65 cases and 983 controls from Guangdong province, 125 cases and 1110 controls from Beijing (northern China), and 60 cases and 2476 controls from Singapore. We used imputation and conditional logistic regression analyses to fine-map the associations. We also did a meta-analysis of the replication series and of the entire dataset. FINDINGS: Associations exceeding the genome-wide significance threshold (p<5 × 10(-8)) were seen at 51 single-nucleotide polymorphisms (SNPs) mapping to the class II MHC region on chromosome 6, with rs9277378 (located in HLA-DPB1) having the strongest association with NKTCL susceptibility (p=4·21 × 10(-19), odds ratio [OR] 1·84 [95% CI 1·61-2·11] in meta-analysis of entire dataset). Imputation-based fine-mapping across the class II MHC region suggests that four aminoacid residues (Gly84-Gly85-Pro86-Met87) in near-complete linkage disequilibrium at the edge of the peptide-binding groove of HLA-DPB1 could account for most of the association between the rs9277378*A risk allele and NKTCL susceptibility (OR 2·38, p value for haplotype 2·32 × 10(-14)). This association is distinct from MHC associations with Epstein-Barr virus infection. INTERPRETATION: To our knowledge, this is the first time that a genetic variant conferring an NKTCL risk is noted at genome-wide significance. This finding underlines the importance of HLA-DP antigen presentation in the pathogenesis of NKTCL. FUNDING: Top-Notch Young Talents Program of China, Special Support Program of Guangdong, Specialized Research Fund for the Doctoral Program of Higher Education (20110171120099), Program for New Century Excellent Talents in University (NCET-11-0529), National Medical Research Council of Singapore (TCR12DEC005), Tanoto Foundation Professorship in Medical Oncology, New Century Foundation Limited, Ling Foundation, Singapore National Cancer Centre Research Fund, and the US National Institutes of Health (1R01AR062886, 5U01GM092691-04, and 1R01AR063759-01A1).

Verbal Versus Figural Fluency Tests in Currently Ill and Weight Restored Anorexia Nervosa Patients.

Fluency tests allow domain-specific assessment of verbal and non-verbal executive functions (EF) comparison and also enable utilizing of both quantitative and qualitative scoring methods. Thirty-five currently ill anorexia nervosa patients (PANs), 33 weight-restored patients (WRAN) and 47 healthy controls (HCs) were administered the word fluency test and the five-point test. Results show that WRANs tended to perseverate more than HCs in the verbal-fluency test. In addition, PANs produced significantly less correct figures and perseverated more than HCs and WRANs; HCs used more strategy methods than PANs and WRANs. Additionally, a positive correlation was found in the HC group between the total number of words in the verbal phonemic test and the number of designs produced and the number of correct designs. No such correlations were found in both anorexia groups. In conclusion, there is a differentiation between verbal and non-verbal EF in PANs and WRANs, showing a deficiency in the non-verbal domain. These findings may contribute to our understanding of the cognitive nature of the disorder.

Association between the dopamine D4 receptor gene exon III variable number of tandem repeats and political attitudes in female Han Chinese.

Twin and family studies suggest that political attitudes are partially determined by an individual's genotype. The dopamine D4 receptor gene (DRD4) exon III repeat region that has been extensively studied in connection with human behaviour, is a plausible candidate to contribute to individual differences in political attitudes. A first United States study provisionally identified this gene with political attitude along a liberal-conservative axis albeit contingent upon number of friends. In a large sample of 1771 Han Chinese university students in Singapore, we observed a significant main effect of association between the DRD4 exon III variable number of tandem repeats and political attitude. Subjects with two copies of the 4-repeat allele (4R/4R) were significantly more conservative. Our results provided evidence for a role of the DRD4 gene variants in contributing to individual differences in political attitude particularly in females and more generally suggested that associations between individual genes, and neurochemical pathways, contributing to traits relevant to the social sciences can be provisionally identified.

The sorting test of the D-KEFS in current and weight restored anorexia nervosa patients.

OBJECTIVE: Efforts have been made to characterize executive functions (EF) in anorexia nervosa (AN) both in the acute stage of the illness and after weight gain, yet many questions remain. The question of verbal versus visuo-perceptual stimuli in this regard has not been adequately addressed. The aim of this study is to further examine EF in women with past and present AN and to compare their performances in verbal and visual modalities with women who have never suffered from an eating disorder. METHOD: Thirty-five underweight AN patients, 33 weight-restored patients symptom-free for at least 2 years, and 48 healthy female controls completed the Delis-Kaplan Executive Function System Sorting Test, so as to evaluate their EF. RESULTS: No differences were observed between the scores of women with current and past AN. Both groups scored lower than controls on most test variables. However, while in the visuo-perceptual domain the performance of the AN groups was worse than that of controls, in the verbal domain they performed similarly to them. DISCUSSION: Women with a past or present diagnosis of AN show difficulties in visuo-perceptual EF, whereas verbal EF seem to be preserved. There may be a dissociation between verbal and visuo-perceptual EF that persists after weight restoration.

Common oxytocin receptor gene (OXTR) polymorphism and social support interact to reduce stress in humans.

The neuropeptide oxytocin has played an essential role in the regulation of social behavior and attachment throughout mammalian evolution. Because recent studies in humans have shown that oxytocin administration reduces stress responses and increases prosocial behavior, we investigated whether a common single nucleotide polymorphism (rs53576) in the oxytocin receptor gene (OXTR) might interact with stress-protective effects of social support. Salivary cortisol samples and subjective stress ratings were obtained from 194 healthy male participants before, during, and after a standardized psychosocial laboratory stress procedure. Participants were randomly assigned either to prepare alone or to receive social support from their female partner or close female friend while preparing for the stressful task. Differential stress responses between the genotype groups were observed depending on the presence or absence of social support. Only individuals with one or two copies of the G allele of rs53576 showed lower cortisol responses to stress after social support, compared with individuals with the same genotype receiving no social support. These results indicate that genetic variation of the oxytocin system modulates the effectiveness of positive social interaction as a protective buffer against a stressful experience.

Employing executive functions of perceptual and memory abilities in underweight and weight-restored anorexia nervosa patients.

PURPOSE: Executive functions (EF) have been widely investigated in anorexia nervosa (AN) revealing difficulties in various aspects. We aimed at testing the effects of EF on stimuli perception and its representations in memory. METHODS: Thirty AN underweight patients, 30 weight-restored AN patients, and 44 control participants, were recruited. Various EF were assessed using the Rey-Osterrieth Complex Figure Test, analyzed with the Boston Qualitative Scoring System. RESULTS: No differences were found in visuo-constructional measures in either AN groups compared to controls on the copy and memory stages. However, both groups performed significantly worse than controls on most EF variables in the copy stage, while in the immediate and delayed memory stages the difference was less substantial. CONCLUSIONS: Difficulties in EF among AN patients, current and weight restored, are more pronounced in the perceptual module and less so when employed through memory retrieval. The pattern, which is apparent after weight gain, suggests that there is no ameliorative effect on these difficulties.

Identification of a functional rare variant in autism using genome-wide screen for monoallelic expression.

Recent work has led to the identification of several susceptibility genes for autism spectrum disorder (ASD) and an increased appreciation of the importance of rare and de novo mutations. Some of the mutations may be very hard to detect using current strategies, especially if they are located in regulatory regions. We present a new approach to identify functional mutations that exploit the fact that many rare mutations disrupt the expression of genes from a single parental chromosome. The method incorporates measurement of the relative expression of the two copies of a gene across the genome using single nucleotide polymorphism arrays. Allelic expression has been successfully used to study common regulatory polymorphisms; however, it has not been implemented as a screening tool for rare mutation. We tested the potential of this approach by screening for monoallelic expression in lymphoblastoid cell lines derived from a small ASD cohort. After filtering regions shared across multiple samples, we identified genes showing monoallelic expression in specific ASD samples. Validation by quantitative sequencing demonstrated that the genes (or only part of them) are monoallelic expressed. The genes included both previously suspected risk factors for ASD and novel candidates. In one gene, named autism susceptibility candidate 2 (AUTS2), we identified a rare duplication that is likely to be the cause of monoallelic expression. Our results demonstrate the ability to identify rare regulatory mutations using genome-wide allelic expression screens, capabilities that could be expanded to other diseases, especially those with suspected involvement of rare dominantly acting mutations.

Boys' serotonin transporter genotype affects maternal behavior through self-control: a case of evocative gene-environment correlation.

Self-control, involving processes such as delaying gratification, concentrating, planning, following instructions, and adapting emotions and behavior to situational requirements and social norms, may have a profound impact on children's adjustment. The importance of self-control suggests that parents are likely to modify their parenting based on children's ability for self-control. We study the effect of children's self-control, a trait partially molded by genetics, on their mothers' parenting, a process of evocative gene-environment correlation. Israeli 3.5-year-old twins (N = 320) participated in a lab session in which their mothers' parenting was observed. DNA was available from most children (N = 228). Mothers described children's self-control in a questionnaire. Boys were lower in self-control and received less positive parenting from their mothers, in comparison with girls. For boys, and not for girls, the serotonin transporter linked polymorphic region gene predicted mothers' levels of positive parenting, an effect mediated by boys' self-control. The implications of this evocative gene-environment correlation and the observed sex differences are discussed.

Imaging genetics for utility of risks over gains and losses.

One tenet of behavioral economics is the asymmetry in how decision makers evaluate risks involving gains versus risks involving losses. Correspondingly, an increasingly important question is what neuroanatomical and neurochemical correlates underpin valuation over gains and losses. By employing an imaging genetics strategy, this paper aims at identifying the specific neurotransmitter pathways underlying these decision making processes. We find enhanced striatal activation responding to increases in the magnitude of utility for risks over gains and to increases in the magnitude of disutility for risks over losses, while increased amygdala activation correlates only with the disutility for risks over losses. Stratifying brain activation by genotype, we find that a well-characterized polymorphism in the dopamine transporter (DAT1) contributes to individual differences in striatal response for gain-oriented risks, whereas a polymorphism in the serotonin transporter (STin2) partially accounts for individual differences in amygdala responses for loss-oriented risks. Together, our results suggest the role of the amygdala and corresponding serotonergic pathway in evaluating losses. This further corroborates the hypothesis of serotonin being linked to dopamine in an "opponent partnership".

The contributions of oxytocin and vasopressin pathway genes to human behavior.

Arginine vasopressin (AVP) and oxytocin (OXT) are social hormones and mediate affiliative behaviors in mammals and as recently demonstrated, also in humans. There is intense interest in how these simple nonapeptides mediate normal and abnormal behavior, especially regarding disorders of the social brain such as autism that are characterized by deficits in social communication and social skills. The current review examines in detail the behavioral genetics of the first level of human AVP-OXT pathway genes including arginine vasopressin 1a receptor (AVPR1a), oxytocin receptor (OXTR), AVP (AVP-neurophysin II [NPII]) and OXT (OXT neurophysin I [NPI]), oxytocinase/vasopressinase (LNPEP), ADP-ribosyl cyclase (CD38) and arginine vasopressin 1b receptor (AVPR1b). Wherever possible we discuss evidence from a variety of research tracks including molecular genetics, imaging genomics, pharmacology and endocrinology that support the conclusions drawn from association studies of social phenotypes and detail how common polymorphisms in AVP-OXT pathway genes contribute to the behavioral hard wiring that enables individual Homo sapiens to interact successfully with conspecifics. This article is part of a Special Issue entitled Oxytocin, Vasopressin, and Social Behavior.

Human maternal behaviour is associated with arginine vasopressin receptor 1A gene.

Parenting is one of the main influences on children's early development, and yet its underlying genetic mechanisms have only recently begun to be explored, with many studies neglecting to control for possible child effects. This study focuses on maternal behaviour and on an allele at the RS3 promoter region of the arginine vasopressin receptor 1A (AVPR1A) gene, previously associated with autism and with higher amygdala activation in a face-matching task. Mothers were observed during a free-play session with each of their 3.5-year-old twins. Multilevel regression analyses revealed that mothers who are carriers of the AVPR1A RS3 allele tend to show less structuring and support throughout the interaction independent of the child's sex and RS3 genotype. This finding advances our understanding of the genetic influences on human maternal behaviour.

Asymmetric valuation and belief updating over gain and loss in risky decision making: A behavioral and electrophysiological investigation.

Decisions under risk, either for gain or loss, are ubiquitous in our daily life. However, the extent to which the valence (gain or loss) of risky financial choices shapes outcome valuation and belief updating is a relatively overlooked research area. In the current study, we image neural activity using electroencephalography (EEG) combined with a financial decision task to investigate outcome valuation and belief updating. In the experimental task, subjects can either choose to take the risky gamble (stock) or the safe option (bond) and then report their belief over the quality of stock option in a trial-by-trial manner. Although the actual probabilities of the risky option are symmetric over gain and loss, we found an asymmetric effect of belief updating and risk preference, viz. the subjects tend to both report a higher probability for the stock to win and be more risk taking for potential gains compared to symmetric losses. The EEG data following feedback of stock payoff represents a parallel pattern which is resonant with the behavioral results. Notably, there is generally a greater FRN difference for feedback (correct vs. incorrect) in the gain condition compared to the loss condition, and the deflection of P300 is more prominent in gain condition than loss condition irrespective of the correctness. Lastly, while the P300 could be predictive for the subsequent probability estimate in both conditions (gain and loss), the FRN is only predictive for belief updating in the gain rather than loss condition. Therefore, both the behavioral and electrophysiological findings indicate an unbalanced processing of valence in shaping decisions under risk within financial learning in an experiential framework.