br Conclusion The present study

Conclusion The present study demonstrated a link between the 5-HTTLPR polymorphism and neural indices of selective attention in lower SES preschoolers. Compared to their long homozygote peers, children who carried at least one copy of the short allele displayed more pronounced attention effects, as measured by ERPs. These findings suggest that carrying at least one short allele of 5-HTTLPR may confer enhanced neural mechanisms of selective attention in preschool-age children from lower SES backgrounds. Further research is needed to understand the interactions between the 5-HTTLPR polymorphism and other candidate polymorphisms in the context of diverse environmental conditions. Future studies that address these issues can advance our understanding of the biological bases for neural mechanisms of selective attention, which are at risk in lower SES children. Additionally, the present study lays the groundwork for future research that can extend the gene-by-environment framework, common in research on vulnerability and resilience to psychopathology, to research on risk and resilience for key cognitive skills. Such efforts that combine neuroimaging with the study of genetic factors carry the potential to greatly improve our understanding of how individual differences in cognitive abilities emerge and develop (Posner et al., 2007) and how experiences shape the developing brain.
Acknowledgements This research was made possible by Department of Education/Institute of Education Science Grant R305B070018 and National Institutes of Health/National Institute on Deafness and Other Communication Disorders Grant R01 DC000481 (to H.J.N.). We thank members of the Brain Development Lab for their support in data acquisition and processing, Pascale Voelker for her contributions to the genetic analyses, and Marie Braasch Chelberg for her helpful comments on an earlier version of the manuscript.
Introduction Neighborhoods matter. Beyond individual or family socioeconomic status (SES), neighborhood level characteristics (e.g., crime, social disorder, physical deterioration) are associated with cognitive development, externalization and a variety of other mental health outcomes (Evans and English, 2002; Mair et al., 2008; Ross and Mirowsky, 2001). During adolescence, neighborhood environments may shape a variety of adolescent behaviors, including delinquency and risk taking (Sampson, 1997). In this leukotriene receptor antagonist same developmental period, neural structures supporting reward function and self-regulation are undergoing dramatic reorganization and pruning (Spear, 2000). Thus, adolescence may constitute a sensitive period during which neighborhood characteristics contribute to the development of adult reward anticipation and pursuit. Using functional neuroimaging, the current study draws on Life History Theory (LHT) (Cabeza de Baca et al., 2016; Gregory et al., 2009) to suggest that adolescent neighborhoods may play a role in adult neural sensitivity to the anticipation of rewards. LHT describes individual development as a process of resolving competing biological challenges through tradeoffs. Environments with abundant and reliable resources encourage “slow” strategies that are low-risk and focused on long-term outcomes, encouraging delay of gratification. Conversely, environments with scarce and unreliable resources encourage “fast” strategies that are relatively high-risk and present-focused, encouraging delay discounting and immediate gratification (Ellis et al., 2009; Griskevicius et al., 2013; Wilson and Daly, 1997). LHT suggests that unreliable environments select for riskier, more reward sensitive, and more impulsive behaviors (Belsky et al., 1991; Ellis et al., 2009; Figueredo et al., 2006). Furthermore, since it is the developmental context that matters, adult access to resources should matter less in the development of these phenotypes.
Methods
Results
Discussion
Conclusion Taken together, the pattern found in our data is consistent with an LHT account of how early environments play a role in adult reward anticipation. Moreover, our results are consonant with work suggesting, for example, that midbrain dopaminergic activity associated with reward anticipation increases as the unpredictability of the reward increases (Fiorillo et al., 2003), or that, in rats, exposure to physical stress (e.g., glucocorticoid injections, restraints) reduces the number of inhibitory dopamine receptors in frontal regions of the brain, even while increasing the number of dopaminergic receptors in mesolimbic systems (El-Khodor and Boksa, 1997; McArthur et al., 2005). Importantly, these and similar effects are accompanied by increased locomotion, motivation, novelty seeking, and indiscriminant reward seeking behavior—all well-known behavioral correlates of heightened reward anticipation and impulsivity (Martinez-Tellez et al., 2009).