Project description:BackgroundA wide array of socioeconomic status (SES) indicators tend to show differential effects for members of diverse social groups. Limited knowledge exists on ethnic variation in the effects of family income on delay discounting which is predictor of risk behaviors.ObjectivesThis study tested whether the effect of family income on delayed gratification differs between Latino and non-Latino children.Methods and materialsIn this cross-sectional analytical study, data came from wave one of the Adolescent Brain Cognitive Development (ABCD) study which included 3903 non-Latino or Latino Black or White American children between ages 9 and 10 years old. The predictor was family income. Data were collected in 21 sits in the US in 2018. The outcome was children's delay discounting. We measured delay discounting, which reflected individuals' tendency to assign less value to remote outcomes and rewards (inversely correlated with delayed gratification). Using SPSS 22.0, linear regression was used for data analysis.ResultsAccording to our pooled sample regression, higher family income was associated with lower children delay discounting (Beta= -0.05, p = .021). We found a significant interaction between family income and ethnicity, suggesting that the association between family income and delay discounting is stronger for Latino than non-Latino children (Beta= -0.09, p = .043).ConclusionsNot all ethnic disparities are due to SES gaps; differential returns of socioeconomic status indicators, such as family income, across diverse social groups also contribute to ethnic disparities in health.
Project description:We examined the neural basis of self-regulation in individuals from a cohort of preschoolers who performed the delay-of-gratification task 4 decades ago. Nearly 60 individuals, now in their mid-forties, were tested on "hot" and "cool" versions of a go/nogo task to assess whether delay of gratification in childhood predicts impulse control abilities and sensitivity to alluring cues (happy faces). Individuals who were less able to delay gratification in preschool and consistently showed low self-control abilities in their twenties and thirties performed more poorly than did high delayers when having to suppress a response to a happy face but not to a neutral or fearful face. This finding suggests that sensitivity to environmental hot cues plays a significant role in individuals' ability to suppress actions toward such stimuli. A subset of these participants (n = 26) underwent functional imaging for the first time to test for biased recruitment of frontostriatal circuitry when required to suppress responses to alluring cues. Whereas the prefrontal cortex differentiated between nogo and go trials to a greater extent in high delayers, the ventral striatum showed exaggerated recruitment in low delayers. Thus, resistance to temptation as measured originally by the delay-of-gratification task is a relatively stable individual difference that predicts reliable biases in frontostriatal circuitries that integrate motivational and control processes.
Project description:Self-control underlies cognitive abilities such as decision making and future planning. Delay of gratification is a measure of self-control and involves obtaining a more valuable outcome in the future by tolerating a delay or investing a greater effort in the present. Contextual issues, such as reward visibility and type, may influence delayed gratification performance, although there has been limited comparative investigation between humans and other animals, particularly non-primate species. Here, we adapted an automated 'rotating tray' paradigm used previously with capuchin monkeys to test for delay of gratification ability that requires little pre-test training, where the subject must forgo an immediate, less preferred reward for a delayed, more preferred one. We tested New Caledonian crows and 3-5-year-old human children. We manipulated reward types to differ in quality or quantity (Experiments 1 and 2) as well as visibility (Experiment 2). In Experiments 1 and 2, both species performed better when the rewards varied in quality as opposed to quantity, though performed above chance in both conditions. In Experiment 1, both crows and children were able to delay gratification when both rewards were visible. In Experiment 2, 5-year-old children outperformed 3- and 4-year olds, though overall children still performed well, while the crows struggled when reward visibility was manipulated, a result which may relate to difficulties in tracking the experimenters' hands during baiting. We discuss these findings in relation to the role of contextual issues on self-control when making species comparisons and investigating the mechanisms of self-control.
Project description:Resonance can occur in bistable dynamical systems due to the interplay between noise and delay (τ) in the absence of a periodic input. We investigate resonance in a two-neuron model with mutual time-delayed inhibitory feedback. For appropriate choices of the parameters and inputs three fixed-point attractors co-exist: two are stable and one is unstable. In the absence of noise, delay-induced transient oscillations (referred to herein as DITOs) arise whenever the initial function is tuned sufficiently close to the unstable fixed-point. In the presence of noisy perturbations, DITOs arise spontaneously. Since the correlation time for the stationary dynamics is ∼τ, we approximated a higher order Markov process by a three-state Markov chain model by rescaling time as t → 2sτ, identifying the states based on whether the sub-intervals were completely confined to one basin of attraction (the two stable attractors) or straddled the separatrix, and then determining the transition probability matrix empirically. The resultant Markov chain model captured the switching behaviors including the statistical properties of the DITOs. Our observations indicate that time-delayed and noisy bistable dynamical systems are prone to generate DITOs as switches between the two attractors occur. Bistable systems arise transiently in situations when one attractor is gradually replaced by another. This may explain, for example, why seizures in certain epileptic syndromes tend to occur as sleep stages change.
Project description:Delayed reward discounting (DRD) is a behavioral economic measure of impulsivity, reflecting how rapidly a reward loses value based on its temporal distance. In humans, more impulsive DRD is associated with susceptibility to a number of psychiatric diseases (e.g., addiction, ADHD), health outcomes (e.g., obesity), and lifetime outcomes (e.g., educational attainment). Although the determinants of DRD are both genetic and environmental, this review focuses on its genetic basis. Both rodent studies using inbred strains and human twin studies indicate that DRD is moderately heritable, a conclusion that was further supported by a recent human genome-wide association study (GWAS) that used single nucleotide polymorphisms (SNP) to estimate heritability. The GWAS of DRD also identified genetic correlations with psychiatric diagnoses, health outcomes, and measures of cognitive performance. Future research priorities include rodent studies probing putative genetic mechanisms of DRD and human GWASs using larger samples and non-European cohorts. Continuing to characterize genomic influences on DRD has the potential to yield important biological insights with implications for a variety of medically and socially important outcomes.
Project description:Delayed pubertal onset has many etiologies, but on average two-thirds of patients presenting with late puberty have self-limited (or constitutional) delayed puberty. Self-limited delayed puberty often has a strong familial basis. Segregation analyses from previous studies show complex models of inheritance, most commonly autosomal dominant, but also including autosomal recessive, bilineal, and X-linked. Sporadic cases are also observed. Despite this, the neuroendocrine mechanisms and genetic regulation remain unclear in the majority of patients with self-limited delayed puberty. Only rarely have mutations in genes known to cause aberrations of the hypothalamic-pituitary-gonadal axis been identified in cases of delayed puberty, and the majority of these are in relatives of patients with congenital hypogonadotropic hypogonadism (CHH), for example in the FGFR1 and GNRHR genes. Using next generation sequencing in a large family with isolated self-limited delayed puberty, a pathogenic mutation in the CHH gene HS6ST1 was found as the likely cause for this phenotype. Additionally, a study comparing the frequency of mutations in genes that cause GnRH deficiency between probands with CHH and probands with isolated self-limited delayed puberty identified that a significantly higher proportion of mutations with a greater degree of oligogenicity were seen in the CHH group. Mutations in the gene IGSF10 have been implicated in the pathogenesis of familial late puberty in a large Finnish cohort. IGSF10 disruption represents a fetal origin of delayed puberty, with dysregulation of GnRH neuronal migration during embryonic development presenting for the first time in adolescence as late puberty. Some patients with self-limited delayed puberty have distinct constitutional features of growth and puberty. Deleterious variants in FTO have been found in families with delayed puberty with extremely low BMI and maturational delay in growth in early childhood. Recent exciting evidence highlights the importance of epigenetic up-regulation of GnRH transcription by a network of miRNAs and transcription factors, including EAP1, during puberty. Whilst a fascinating heterogeneity of genetic defects have been shown to result in delayed and disordered puberty, and many are yet to be discovered, genetic testing may become a realistic diagnostic tool for the differentiation of conditions of delayed puberty.
Project description:Indonesian students perform poorly compared with students in other countries, despite education taking a significant portion of the national budget. Although poor infrastructure is often blamed for this failure, several reports show that it may not be the sole determinant of learning outcomes. Using the concepts of a growth mindset and delayed gratification as proxies for human behavior, we conducted a field survey of four highly disadvantaged private schools in Depok, West Java, Indonesia to observe how human behaviors affect learning outcomes. We use a self-administered mathematics test to measure learning outcomes, and construct a questionnaire based on Dweck's Implicit Theory of Intelligence to measure students' growth mindset. Delayed gratification is measured using a Convex Time Budget (CTB) questionnaire. Controlling for various student characteristics, our estimations show that a more pronounced growth mindset is associated with better math scores. Meanwhile, delayed gratification has mixed effects on learning outcomes: it has no significant effect when the relationship is estimated using an Interval Censored Regression (ICR), but has some statistical significance when an Ordinary Least Square (OLS) regression is used. These results imply that a student's beliefs on a growing intelligence can affect their academic achievement, whereas the ability to resist temptation has inconclusive effects on academic achievement. This difference may be caused by several factors such as the developmental stage of students. Interestingly, satisfactory teaching practices do not necessarily lead to better math scores. Our findings, therefore, suggest that future education policy design must consider aspects of human behavior in order to more optimally benefit students.
Project description:Individuals are willing to sacrifice their own resources to promote equality in groups. These costly choices promote equality and are associated with behavior that supports cooperation in humans, but little is known about the brain processes involved. We use functional MRI to study egalitarian preferences based on behavior observed in the "random income game." In this game, subjects decide whether to pay a cost to alter group members' randomly allocated incomes. We specifically examine whether egalitarian behavior is associated with neural activity in the ventromedial prefrontal cortex and the insular cortex, two regions that have been shown to be related to social preferences. Consistent with previous studies, we find significant activation in both regions; however, only the insular cortex activations are significantly associated with measures of revealed and expressed egalitarian preferences elicited outside the scanner. These results are consistent with the notion that brain mechanisms involved in experiencing the emotional states of others underlie egalitarian behavior in humans.
Project description:Cooperation among genetically unrelated individuals is a fundamental aspect of society, but it has been a longstanding puzzle in biological and social sciences. Recently, theoretical studies in biology and economics showed that conditional cooperation-cooperating only with those who have exhibited cooperative behavior-can spread over a society. Furthermore, experimental studies in psychology demonstrated that people are actually conditional cooperators. In this study, we used functional magnetic resonance imaging to investigate the neural system underlying conditional cooperation by scanning participants during interaction with cooperative, neutral and non-cooperative opponents in prisoner's dilemma games. The results showed that: (i) participants cooperated more frequently with both cooperative and neutral opponents than with non-cooperative opponents; and (ii) a brain area related to cognitive inhibition of pre-potent responses (right dorsolateral prefrontal cortex) showed greater activation, especially when participants confronted non-cooperative opponents. Consequently, we suggest that cognitive inhibition of the motivation to cooperate with non-cooperators drives the conditional behavior.
Project description:It remains unclear whether and, if so, how nonhuman animals make on-the-fly predictions during pursuit. Here we used a novel laboratory pursuit task that incentivizes the prediction of future prey positions. We trained three macaques to perform a joystick-controlled pursuit task in which prey follow intelligent escape algorithms. Subjects aimed toward the likely future positions of the prey, which indicated that they generate internal predictions and use these to guide behavior. We then developed a generative model that explains real-time pursuit trajectories and showed that our subjects use prey position, velocity and acceleration to make predictions. We identified neurons in the dorsal anterior cingulate cortex whose responses track these three variables. These neurons multiplexed prediction-related variables with a distinct and explicit representation of the future position of the prey. Our results provide a clear demonstration that the brain can explicitly represent future predictions and highlight the critical role of anterior cingulate cortex for future-oriented cognition.