Linking Gene, Brain, and Behavior: DRD4, Frontal Asymmetry, and Temperament

ABSTRACT— Gene-environment interactions involving exogenous environmental factors are known to shape behavior and personality development. Although gene-environment interactions involving endogenous environmental factors are hypothesized to play an equally important role, this conceptual approach has not been empirically applied in the study of early-developing temperament in humans. Here we report evidence for a gene- endo environment (i.e., resting frontal brain electroencephalogram, EEG, asymmetry) interaction in predicting child temperament. The dopamine D4 receptor (DRD4) gene (long allele vs. short allele) moderated the relation between resting frontal EEG asymmetry (left vs. right) at 9 months and temperament at 48 months. Children who exhibited left frontal EEG asymmetry at 9 months and who possessed the DRD4 long allele were significantly more soothable at 48 months than other children. Among children with right frontal EEG asymmetry at 9 months, those with the DRD4 long allele had significantly more difficulties focusing and sustaining attention at 48 months than those with the DRD4 short allele. Resting frontal EEG asymmetry did not influence temperament in the absence of the DRD4 long allele. We discuss how the interaction of genetic and endoenvironmental factors may confer risk and protection for different behavioral styles in children.     

Neural Correlates of Reward Processing in Adolescents With a History of Inhibited Temperament

ABSTRACT— Functional imaging data were acquired during performance of a reward-contingency task in a unique cohort of adolescents (ages 14–18 years) who were characterized since infancy on measures of temperamental behavioral inhibition. Neural activation was examined in striatal structures (nucleus accumbens, putamen, caudate) with a known role in facilitating response to salient reward-related cues. Adolescents with a history of behavioral inhibition, relative to noninhibited adolescents, showed increased activation in the nucleus accumbens when they believed their selection of an action would affect reward outcome. Neural responses did not differ between the two groups when participants made a prespecified response that they knew would result in reward or when they produced random motor responses that they knew would not be rewarded. These results link inhibited temperament and perturbed neural responses to reward-contingency cues.     

Target-biting behavior of individually and group-housed mice and rats

The effects of housing conditions (individual or grouped) on the biting of an inanimate target by confined male mice and rats were measured. It was observed that, for both mice and rats, individual housing markedly increased the number of target bites per session. These results indicate that the target-biting paradigm is sensitive to those factors responsible for the increase in fighting behavior following individual housing.     

Education and testing strategy for large-scale cystic fibrosis carrier screening

Population-based screening for cystic fibrosis carrier mutations presents a number of challenges for genetic counselors, owing primarily to the inability of current DNA testing technology to identify all possible mutations and the difficulty involved in conveying the concept of residual risk to those patients who test negative. To address these issues, we are conducting a pilot study, as part of a consortium established by the National Center for Human Genome Research, to explore the efficacy, acceptance, and psychosocial impact of various approaches to carrier screening in an ethnically diverse Southern California population. This article reports the patient instructional and screening strategies we developed in the initial phase of the project in order to optimize our chances of answering these questions and delivering this service on a large scale.     

Programming experiments on a TERAK 8510/A microcomputer

In the course of bringing up one’s first experimental microcomputer system, certain standard problems occur that are trivial to the experienced programmer but are great blocks to the novice. In this spirit, some paradigms that were implemented on a TERAK 8510/a microcomputer, and the related problems, are described. Specific topics include some consideration of timing procedures for reaction time experiments and how to handle large text files on small floppy disk systems.