The Importance of Context in the US Preexposure Effect in CTA: Novel versus Latently Inhibited Contextual Stimuli

Three experiments were conducted to examine the role of novel contextual stimuli in producing the unconditioned stimulus (US) preexposure effect. Experiment 1 demonstrated that novel contextual stimuli produce a significantly stronger US preexposure effect than familiar or “latently inhibited” contextual stimuli. Moreover, subjects preexposed in the presence of latently inhibited contextual cues failed to show a significant US preexposure effect. Experiments 2 and 3 attempted to provide evidence that the addition of a single novel stimulus to the latently inhibited context would result in a significantly stronger US preexposure effect than when no such novel cue was present. Experiment 3 was able to demonstrate this effect. Results are consistent with the Rescorla–Wagner (1972) model of conditioning.     

Accuracy of memories from childhood and adolescence related to growth and size

The ability of middle-aged adults to recall their body size and events occurring up to 40 years earlier was assessed. Ninety-one subjects recalled their relative height, weight, and fatness during childhood, early adolescence and late adolescence. Accuracy of these memories was compared with the accuracy of current reports. The ability to accurately date benchmarks of their maturation such as menarche and year of maximal growth in height was also examined. Accuracy of reports did not decline uniformly over time. In general, reports of childhood physical characteristics were at least as accurate as reports of current characteristics; that is, they did not differ significantly from current reports. Males were less accurate in their reports of relative height and fatness during early adolescence and childhood. This project has been funded at least in part with federal funds from the U.S. Department of Agriculture, Agricultural Research Service under contract number 53-3K06-5-10. The contents of this article do not necessarily reflect the views or policies of the U.S. Department of Agriculture, nor does mention of trade names, commercial products, or organizations imply endorsement by the U.S. Government.     

Children with ADHD in Residential Care

Little is known about the characteristics or functioning of children with ADHD in residential care as compared to their non-ADHD peers. This study evaluated data on 538 children with (n = 125) and without (n = 413) ADHD in residential care to determine demographic, mental health, behavioral, and treatment (i.e., medication use) characteristics. Results revealed that both groups presented elevated risks, however, scores for children with ADHD indicated even greater levels of need. Specifically, differences were found between the two groups on demographics (e.g., family reunification status, restrictiveness of prior out-of-home placements), behavior (e.g., attention problems, rule-breaking and aggressive behaviors) and medication status. Findings suggest there is a need for aftercare services to help support families as children transition from care, interventions to address behavior, and medication management through assessment and monitoring.     

Etiologic Subtypes of Attention-Deficit/Hyperactivity Disorder: Brain Imaging, Molecular Genetic and Environmental Factors and the Dopamine Hypothesis

Multiple theories of Attention-Deficit/Hyper- activity Disorder (ADHD) have been proposed, but one that has stood the test of time is the dopamine deficit theory. We review the narrow literature from recent brain imaging and molecular genetic studies that has improved our understanding of the role of dopamine in manifestation of symptoms of ADHD, performance deficits on neuropsychological tasks, and response to stimulant medication that constitutes the most common treatment of this disorder. First, we consider evidence of the presence of dopamine deficits based on the recent literature that (1) confirms abnormalities in dopamine-modulated frontal-striatal circuits, reflected by size (smaller-than-average components) and function (hypoactivation); (2) clarifies the agonist effects of stimulant medication on dopaminergic mechanisms at the synaptic and circuit level of analysis; and (3) challenges the most-widely accepted ADHD-related neural abnormality in the dopamine system (higher-than-normal dopamine transporter [DAT] density). Second, we discuss possible genetic etiologies of dopamine deficits based on recent molecular genetic literature, including (1) multiple replications that confirm the association of ADHD with candidate genes related to the dopamine receptor D4 (DRD4) and the DAT; (2) replication of differences in performance of neuropsychological tasks as a function of the DRD4 genotype; and (3) multiple genome-wide linkage scans that demonstrate the limitations of this method when applied to complex disorders but implicate additional genes that may contribute to the genetic basis of ADHD. Third, we review possible environmental etiologies of dopamine deficits based on recent studies of (1) toxic substances that may affect the dopamine system in early development and contribute substantially to the etiology of ADHD; (2) fetal adaptations in dopamine systems in response to stress that may alter early development with lasting effects, as proposed by the developmental origins of health and disease hypothesis; and (3) gene-environment interactions that may moderate selective damage or adaptation of dopamine neurons. Based on these reviews, we identify critical issues about etiologic subtypes of ADHD that may involve dopamine, discuss methods that could be used to address these issues, and review old and new theories that may direct research in this area in the future.     

A typology of behavior problems in preschool children

The purpose of this study was to produce a typology of behavior problems in preschool children. Distinct subtypes were identified through the use of cluster analytic techniques on data from the Behavior Assessment System for Children (BASC)-Parent Rating Scales. Analyses were based on archival data collected on a sample of 268 children, aged 2 to 5 years, who were referred to determine their suitability for a day treatment program. Five distinct and reliable subtypes of preschool children's behavior problems emerged. Ratings of adaptive and social skills based on the BASC Adaptive Scales and measures from the Parenting Stress Index served as external variables to assess the distinctiveness of the derived subtypes. The findings provide evidence for the reliability and validity of the subtypes identified in this study that are consistent with the findings of previous subtyping investigations focusing on school-aged children.     

Bullying in college by students and teachers

This study explored bullying in college by students and teachers. The reports of a sample of 1,025 undergraduates indicated that 24.7% had seen students bully other students occasionally and 2.8% very frequently, 5% had been bullied by students occasionally and 1.1% very frequently, 12.8% had seen teachers bully students occasionally and 1.9% very frequently, 4.2% had been bullied by teachers occasionally and .5% very frequently, while 3.2% had bullied other students occasionally and 1.9% very frequently. Male students bullied significantly more than females. Student bullying was predicted by having seen other students bully, and by having been bullied by both students and teachers.     

Early development of subcortical regions involved in non-cued attention switching

This study examined the cognitive and neural development of attention switching using a simple forced-choice attention task and functional magnetic resonance imaging Fourteen children and adults made discriminations among stimuli based on either shape or color. Performance on these trials was compared to performance during blocked trials requiring all color or all shape discriminations. Magnetic resonance echo planar images were acquired during performance of the task. Both children and adults showed robust bilateral activity of the caudate nucleus when switching attention between color and shape discriminations that correlated negatively with mean response latency on these trials. However, neither switching costs nor caudate activity correlated with age, suggesting early development of the underlying neural circuitry involved in switching between salient stimulus sets. Overall, children and adults differed in performance and patterns of brain activity on the task, with adults responding more accurately and faster than children, and recruiting more prefrontal and parietal regions. These results suggest an important role of subcortical regions (i.e. caudate nucleus) in non-cued attention switching, with increasing recruitment of cortical regions with age.