Brain Imaging Techniques and Their Applications in Decision-Making Research
Advanced noninvasive neuroimaging techniques such as EEG and fMRI allow researchers to directly observe brain activities while subjects perform various perceptual, motor, and/or cognitive tasks. By combining functional brain imaging with sophisticated experimental designs and data analysis methods, functions of brain regions and their interactions can be examined. A nascent field called neuroeconomics has recently emerged as a result of the enormous success of applications of functional brain imaging techniques in the study of human decision-making. In this article, we first provide an overview of brain imaging techniques, focusing on the recent developments in multivariate analysis and multi-modal data integration. We then present several studies on risky decision making, intertemporal choice, and social decision making, to illustrate how neuroimaging techniques can be used to advance our knowledge on decision making. Finally, we discuss challenges and future directions in neuroeconomics.
Screening for Learning and Memory Mutations: A New Approach
We describe a fully automated, live-in 24/7 test environment, with experimental protocols that measure the accuracy and precision with which mice match the ratio of their expected visit durations to the ratio of the incomes obtained from two hoppers, the progress of instrumental and classical conditioning (trials-to-acquisition), the accuracy and precision of interval timing, the effect of relative probability on the choice of a timed departure target, and the accuracy and precision of memory for the times of day at which food is available. The system is compact; it obviates the handling of the mice during testing; it requires negligible amounts of experimenter/technician time; and it delivers clear and extensive results from 3 protocols within a total of 7-9 days after the mice are placed in the test environment. Only a single 24-hour period is required for the completion of first protocol (the matching protocol), which is strong test of temporal and spatial estimation and memory mechanisms. Thus, the system permits the extensive screening of many mice in a short period of time and in limited space. The software is publicly available.
An Overview on the Genetics of ADHD
Attention Deficit Hyperactivity is a childhood-onset disorder that can persist into adult life. Traditional family, twin and adoption studies have shown that ADHD defined both categorically and dimensionally is familial and heritable. Twin studies are now being used to examine ways of defining the ADHD phenotype, to investigate gender differences, the effects on genes on continuity and comorbidity and to consider gene-environment interplay. Molecular genetic findings on ADHD have mainly arisen from functional candidate gene association studies and a number of pooled and meta-analyses have now been conducted. There is consistent evidence of association between ADHD and a dopamine D4 receptor gene VNTR and a dopamine D5 receptor gene microsatellite marker. More recent evidence from different studies and a pooled analysis suggests that conduct problems in those with ADHD is influenced by the COMT val158/108 met variant. Linkage studies suggest that there are no genes of moderate effect size and findings from large scale whole genome association studies are currently awaited. Overall the evidence to date, suggests that examining gene-phenotype links and testing whether gene variants have modifying effects on the ADHD phenotype are important. The contribution of gene-environment interplay (G x E) to psychopathology is becoming increasingly recognised, although for ADHD little is known on causal environmental risk factors.
The End of Behavioral Genetics?
Although genetic models were in the ascendance within psychology during the early 20(th) century, the association of early behavioral genetic research with the eugenics movement served to discredit the field in the eyes of many. Twin and adoption studies throughout the latter half of the 20(th) century helped to reestablish the importance of behavioral genetic models and set the stage for the current focus of the field on developing and testing models of gene-environment interplay. Research findings on developmental behavioral genetic research, gene-environment interaction, and the use of behavioral genetic models to test causal hypotheses are used to highlight the contributions of contemporary behavioral genetic research to psychological research. It is argued that future efforts to investigate models of gene-environment interplay will depend heavily of the field's ability to identify the specific genetic variants that contribute to individual differences in behavior. The anticipated yield from genome-wide association studies gives much reason to be optimistic about the future vitality of behavior genetics.
The Early Growth and Development Study: Using the Prospective Adoption Design to Examine Genotype-Environment Interplay
The Early Growth and Development Study (EGDS) is a prospective adoption design consisting of 360 linked sets of birth parents, adoptive parents, and adopted children followed from 3 months postpartum through child age 7 years, and an additional 200 linked sets for whom recruitment is underway. The EGDS brings together the study of genotype-environment correlation (rGE) and Genotype x Environment (GxE) interaction to inform intervention development by examining mechanisms whereby family processes mediate or moderate the expression of genetic influences. Participants in the EGDS are recruited through domestic adoption agencies located throughout the United States of America. The assessments occur at 6-month intervals until child age 4-½ years and at ages 6 and 7, when the children are in their 1(st) and 2(nd) years of formal schooling (kindergarten and first grade). The data collection includes measures of child characteristics, birth and adoptive parent characteristics, adoptive parenting, prenatal exposure to drugs and maternal stress, birth parent and adopted child salivary cortisol reactivity, and DNA from all participants. The preliminary analyses suggest evidence for GxE interaction beginning in infancy. An intervention perspective on future developments in the field of behavioral genetics is described.