Age‐related changes in transient and oscillatory brain responses to auditory stimulation during early adolescence

Maturational changes in the capacity to process quickly the temporal envelope of sound have been linked to language abilities in typically developing individuals. As part of a longitudinal study of brain maturation and cognitive development during adolescence, we employed dense‐array EEG and spatiotemporal source analysis to characterize maturational changes in the timing of brain responses to temporal variations in sound. We found significant changes in the brain responses compared longitudinally at two time points in early adolescence, namely 10 years (65 subjects) and 11.5 years (60 of the 65 subjects), as well as large differences between adults, studied with the same protocol ( Poulsen, Picton & Paus, 2007 ), and the children at 10 and 11.5 years of age. The transient auditory evoked potential to tone onset showed decreases in the latency of vertex and T‐complex components, and a highly significant increase in the amplitude of the N1 wave with increasing age. The auditory steady state response to a 40‐Hz frequency‐modulated tone increased in amplitude with increasing age. The peak frequency of the envelope‐following response to sweeps of amplitude‐modulated white noise also increased significantly with increasing age. These results indicate persistent maturation of the cortical mechanisms for auditory processing from childhood into middle adulthood.     

Causality in medicine: Towards a theory and terminology

One of the cornerstones of modern medicine is the search for what causes diseases to develop. A conception of multifactorial disease causes has emerged over the years. Theories of disease causation, however, have not quite been developed in accordance with this view. It is the purpose of this paper to provide a fundamental explication of aspects of causation relevant for discussing causes of disease. The first part of the analysis will discuss discrimination between singular and general causality. Singular causality, as in the specific patient, is a relation between a concrete sequence of causally linked events. General causation, e.g. as in disease etiology, means various categories of causal relations between event types. The paper introduces the concept of a reference case serving as a source for causal inference, reaching beyond the concept of general causality. The second part of the analysis provides exemplification of a theory of causation suitable for discussing singular causation. The chain of events that induce a disease state can be identified as effective causal complexes, each complex composed of nonredundant components, which separately contribute to the effect of the complex, without the individual component being necessary or sufficient in itself to produce the effect. In the third part of the analysis the theory is elaborated further. Causes, defined as nonredundant components, can furthermore be differentiated according to their avoidability, according to theories about human error or by the potential of eradication. Multifactorial models of disease creates a need for systematic approaches to causal factors. The paper proposes a taxonomical terminology that serves this purpose.     

INFORMATION LOSS WHEN ρ IS APPLIED IN NON-NORMAL CASES

The correlation coefficient ρ of two stochastic variables underestimates the dependence between the variables, if they are not bivariately normally distributed. An information theoretical approach to the study of this underestimation is suggested. The method is applied on artificial data.     

Effects of action planning and coping planning within the theory of planned behaviour: A physical activity study of patients undergoing haemodialysis

Objective

Patients on dialysis have low physical activity levels. The aim of the study was to examine the validity of action planning and coping planning within the theory of planned behaviour framework, for predicting physical activity behaviour of patients on haemodialysis.

Design

This is a prospective study design.

Methods

One hundred and forty-four patients who were undergoing haemodialysis were selected from dialysis centres. The mean age of the patients was 56.61 (SD = 11.38) years. The patients completed a questionnaire including variables from the theory of planned behaviour, action planning and coping planning. Physical activity was prospectively assessed at 4-weeks with the validated International Physical Activity Questionnaire self-report measure. A hierarchical regression analysis was performed to examine the effects of action planning and coping planning on physical activity behaviour.

Results

There was a main effect for coping planning but not for action planning. Moreover, the analyses resulted in a significant amount of incremental variance accounted for by the interaction of coping planning and intention.

Conclusion

Results suggest the combination of high levels of coping planning and intention is associated with increases in physical activity.     

Quantitative genetic analysis of latent growth curve models of cognitive abilities in adulthood

Though many cognitive abilities exhibit marked decline over the adult years, individual differences in rates of change have been observed. In the current study, biometrical latent growth models were used to examine sources of variability for ability level (intercept) and change (linear and quadratic effects) for verbal, fluid, memory, and perceptual speed abilities in the Swedish Adoption/Twin Study of Aging. Genetic influences were more important for ability level at age 65 and quadratic change than for linear slope at age 65. Expected variance components indicated decreasing genetic and increasing nonshared environmental variation over age. Exceptions included one verbal and two memory measures that showed increasing genetic and nonshared environmental variance. The present findings provide support for theories of the increasing influence of the environment with age on cognitive abilities.     

Frontolimbic response to negative feedback in clinical depression

Functional neuroimaging suggests that limbic regions of the medial frontal cortex may be abnormally active in individuals with depression. These regions, including the anterior cingulate cortex, are engaged in both action regulation, such as monitoring errors and conflict, and affect regulation, such as responding to pain. The authors examined whether clinically depressed subjects would show abnormal sensitivity of frontolimbic networks as they evaluated negative feedback. Depressed subjects and matched control subjects performed a video game in the laboratory as a 256-channel EEG was recorded. Speed of performance on each trial was graded with a feedback signal of A, C, or F. By 350 ms after the feedback signal, depressed subjects showed a larger medial frontal negativity for all feedback compared with control subjects with a particularly striking response to the F grade. This response was strongest for moderately depressed subjects and was attenuated for subjects who were more severely depressed. Localization analyses suggested that negative feedback engaged sources in the anterior cingulate and insular cortices. These results suggest that moderate depression may sensitize limbic networks to respond strongly to aversive events.     

The Genetic and Environmental Relationship Between General and Specific Cognitive Abilities in Twins Age 80 and Older

In the first twin study of the old-old, individuals 80 years old and older, we examined the relationship between general and specific cognitive abilities from a genetic perspective. That is, we examined the extent to which genetic and environmental factors influence major group factors of cognitive abilities, independent of general cognitive ability. As part of the OctoTwin project in Sweden, general and specific cognitive abilities were assessed in 52 monozygotic and 65 same-sex dizygotic twin pairs 80 years old and older using a battery of seven tests that assess verbal, spatial, speed-of-processing, and memory performance. Results suggest that genetic effects associated with general cognitive ability ( g ) account for the correlation between g and verbal, spatial, and speed-of-processing abilities. No genetic influences were found for these specific cognitive abilities separate from g . In contrast, memory ability appears to be more distinct genetically from g than are other cognitive abilities. Comparison with younger samples suggests that cognitive abilities relating to speed of processing may be genetically dedifferentiated in the old-old.     

Predation, aggression, and activity levels in food-deprived sunfish (Lepomis macrochirus and L. gibbosus): motivational interactions

Three experiments investigated the effects of food deprivation on several behavioral categories in two species of sunfish. In Experiment 1, predatory behavior and general activity were observed under five levels of deprivation. For both species, predation measures increased in a similar negatively accelerating manner with increasing deprivation, while activity changed in a more complex fashion. Experiment 2 examined the effects of deprivation on activity in a novel environment and showed that the deprivation effects of Experiment 1 were masked by the response to the new setting. In Experiment 3, measures of aggression toward intruders of each species were recorded from resident fish of both species under three levels of food deprivation. Both species were more aggressive toward conspecifics, and bluegills were more aggressive overall. Aggression was significatly influenced by food deprivation, with the effects dependent on the species making up the pair. Theories of motivational summation, generalized drive, and activity-mediated aggression were unable to explain the differential effects of hunger on the three behavioral categories observed. A dynamic boundary-state model of behavior control was found to predict the motivational interactions observed between distinct behavioral control systems.     

Contact Experiences Mediate the Relationship Between Five-Factor Model Personality Traits and Ethnic Prejudice

Prejudice has been studied as a function of personality and situation, but there has been little integration of these 2 domains. Our model suggests that people who are especially open and agreeable are more likely to initiate intergroup contact and interpret contact experiences favorably. Such experiences lead to positive intergroup attitudes. To test this mediation hypothesis, participants ( N = 163) completed a measure of (a) the Big Five personality traits, (b) past contact experiences with African Americans, and (c) pro-Black/ anti-Black attitudes. A second study used Asian Americans as the outgroup. In both studies, the model was supported. The results have implications for integrating personality and situational approaches to prejudice and enhancing our understanding of intergroup relations.