Timing is essential for rapid effects of corticosterone on synaptic potentiation in the mouse hippocampus

Stress facilitates memory formation, but only when the stressor is closely linked to the learning context. These effects are, at least in part, mediated by corticosteroid hormones. Here we demonstrate that corticosterone rapidly facilitates synaptic potentiation in the mouse hippocampal CA1 area when high levels of the hormone and high-frequency stimulation coincide in time, but not when corticosterone is given either before or after repetitive stimulation. This effect could not be blocked by antagonists of the mineralocorticoid receptor and glucocorticoid receptor (spironolactone and RU 38486, respectively). These data provide a biological substrate for the important behavioral observation that stress and corticosteroid hormones can facilitate learning and memory processes.     

The relation of lifetime cognitive activity and lifetime access to resources to late-life cognitive function in older African Americans

Research in older Caucasians has demonstrated that cognitive activity is related to cognitive function in late adulthood. Knowledge of this association is limited in older minority populations. We examined the relation of cognitive activity and access to cognitive resources, with cognitive function in a group of 108 older African Americans. We constructed two scales to measure the frequency of cognitive activity and the presence of resources that promote cognitive activity during early and late life. Both measures had high internal consistency and the cognitive activity scale had adequate temporal stability over a 4-week interval. In analyses that controlled for age and education, more frequent lifetime cognitive activity was related to current cognitive function, but lifetime cognitive resources only approached significance. The results suggest that both measures are psychometrically sound in a minority population and that lifetime cognitive activity may contribute to current cognitive function in African Americans.     

In search of shared and nonshared environmental factors in security of attachment: a behavior-genetic study of the association between sensitivity and attachment security

The current article presents results from a twin study of genetic and environmental components of maternal sensitivity and infant attachment and their association. The sample consisted of 136 twin pairs from 2 sites: Leiden, the Netherlands, and London, UK. Maternal sensitivity was assessed in the home at 9-10 months, and infant attachment security was observed in the laboratory at 12 months. The study yielded little evidence that genetic factors are involved in variations between twins in maternal sensitivity ratings but did find that shared variance in maternal sensitivity was able to account for some of the similarity between twins in attachment security. Weak nonshared associations between sensitivity and attachment appeared to suppress the magnitude of the correlation between attachment and sensitivity in twin children. The results could indicate that the attachment security of one twin may depend on the relationship the parent has with the other twin. The results are brought to bear on the validity of attachment theory as a theory of primarily shared environmental effects in children's development and the continuing challenge posed to attachment theory by within-family differences in socioemotional processes.     

Social development from infancy to adolescence: longitudinal and concurrent factors in an adoption sample

In the present longitudinal study, early adopted children (N = 160) were followed from infancy to adolescence to assess the influence of previous and concurrent factors on the children's social development. This study allowed for more conclusive evidence of the influence of early and concurrent rearing experiences and temperament on adolescents' social development, independent of shared genetic factors between children and parents. Results showed that social development and temperament were stable over time and that both previous and current parental sensitivity were important in predicting social development in adolescence. Quality of the early parent-child relationship was indirectly associated with social development in adolescence through the influence on social development in middle childhood. Maternal sensitivity in middle childhood and in adolescence partly buffered the negative effects of difficult temperament on social development in adolescence. Adaptation emerged as the product of both developmental history and current circumstances.     

Strengthening the validity of population-based suicide rate comparisons: an illustration using U.S. military and civilian data

The objectives of this study were to generate precise estimates of suicide rates in the military while controlling for factors contributing to rate variability such as demographic differences and classification bias, and to develop a simple methodology for the determination of statistically derived thresholds for detecting significant rate changes. Suicide rate estimates were calculated for the military population and each service branch over 11 years, directly standardized to the 2000 U.S. population. Military rates were highly comparable across branches and were approximately 20% lower than the civilian rate. Direct adjustment essentially controlled for the demographic confounds in this sample. Applying the Poisson-based method, we demonstrate that suicide rate fluctuations as large as 20-40% in any year may be attributed to random error.     

Loss aversion is an affective forecasting error

Loss aversion occurs because people expect losses to have greater hedonic impact than gains of equal magnitude. In two studies, people predicted that losses in a gambling task would have greater hedonic impact than would gains of equal magnitude, but when people actually gambled, losses did not have as much of an emotional impact as they predicted. People overestimated the hedonic impact of losses because they underestimated their tendency to rationalize losses and overestimated their tendency to dwell on losses. The asymmetrical impact of losses and gains was thus more a property of affective forecasts than a property of affective experience.     

Directional uncertainty in visually guided pointing

Studies of the relationship between stimulus-response uncertainty and reaction times indicate three qualitatively different functions: Hick's law, simple-choice step function, or flat curve (no effect at all). The extent of stimulus-response S-R) compatibility appears to interact with the effects of uncertainty on response times. One possible hypothesis regarding these various S-R uncertainty functions is that uncertainty will have an effect whenever the stimuli and their associated responses are not within the same egocentric spatial coordinates. We tested this hypothesis in 5 undergraduate participants (2 men, M age 18.7 yr., range 18-20) by investigating the time-course of pointing to peripherally located visual targets under four different levels of uncertainty (1, 2, 4, or 8 possible locations). Surprisingly, the resulting response function does not match any of those previously reported. Visually guided pointing produced a quadratic reaction time function as S-R uncertainty increases in log2 steps from 1 to 8.     

Cognitive decline in old age: separating retest effects from the effects of growing older

Repeated administration of cognitive tests improves test performance, making it difficult for researchers to gauge the true extent of age-related cognitive decline. The authors examined this issue using data from the Rush Religious Orders Study and linear mixed-effects models. At annual intervals for up to 8 years, more than 800 older Catholic clergy members completed the same set of 19 cognitive tests from which previously established composite measures of cognitive domains were derived. Retest effects on some measures were substantial and continued to accumulate even after 8 annual test readministrations, but effects on other measures were minimal. Across cognitive measures, retest effects were not related to age, sex, or education. Individual differences in retest effects were substantial but not consistent across cognitive measures. The results suggest that retest-based improvement in cognitive test performance can be substantial and persistent.