The Nature and Significance of Behavioural Genetic Information

In light of the human genome project, establishing the genetic aetiology of complex human diseases has become a research priority within Western medicine. However, in addition to the identification of disease genes, numerous research projects are also being undertaken to identify genes contributing to the development of human behavioural characteristics, such as cognitive ability and criminal tendency. The permissibility of this research is obviously controversial: will society benefit from this research, or will it adversely affect our conceptions of ourselves and each other? When assessing the permissibility of this research, it is important to consider the nature and deterministic significance of behavioural genetic information. Whilst todate there has been much discussion and debate about the properties of genetic information per se and genetic determinism, this has not been applied to behavioural genetic research and its ethical implications. Therefore, this paper elucidates how behavioural genetic information can be distinguished from other types of genetic and non-genetic information and also synthesises the determinative significance of genetic factors for the development of human behavioural traits. Undertaking this analysis enables the ethical issues raised by this research to be debated in an appropriate context and indicates that separate policy considerations are warranted.

     

A novel working memory task for preschoolers: sensitivity to age differences from 3-5 years

Working memory (WM) plays an important role in children’s learning and is linked to later academic and occupational success. Understanding the early development of WM can provide critical clues regarding the underlying structure of executive functions and how they change over the life span. The main objectives of the present study were to (1) investigate age differences in the development of three components of WM (retrieval, substitution, transformation) on a novel preschool WM measure and (2) explore whether findings are consistent with the hierarchical model of WM development by examining perseverative and non-perseverative WM errors. Perseverative errors were hypothesized to be more strongly associated with problems substituting and transforming a representation held in mind, whereas non-perseverative errors were hypothesized to be associated with problems maintaining a representation in mind. Participants were 64 children ranging in age from 3.0 to 5.6 years. The results provide evidence for the sensitivity of the WM task to age differences from 3 to 5 years and support for the hierarchical model of WM development.     

Ensemble coding of faces occurs in children and develops dissociably from coding of individual faces

Ensemble coding allows adults to access useful information about average properties of groups, sometimes even in the absence of detailed representations of individual group members. This form of coding may emerge early in development with initial reports of ensemble coding for simple properties (size, numerosity) in young children and even infants. Here we demonstrate that ensemble coding of faces, which provides information about average properties of social groups, is already present in 6–8‐year‐old children. This access to average information increases with age from 6 to 18 years and its development is dissociable from age‐related improvements in the coding of individual face identities. This dissociation provides the first direct evidence that distinct processes underlie ensemble and individual coding of face identity, evidence that has been lacking from adult studies. More generally, our results add to the emerging evidence for impressively mature sensitivity to statistical properties of the visual environment in children. They indicate that children have access to gist information about social groups that may facilitate adaptive social behaviour.     

Evidence for Free Radical-Mediated Reduction of Lymphocytic 5′-Ectonucleotidase During Stress

Previously we showed that stress and depression could result in a 50% lowering of lymphocytic 5-ectonucleotidase (NT) which could be resolved by a diet high in antioxidants. This study suggested that high levels of free radicals mediated by stress/depression may be involved in lowering NT activities. The aim of the present study was to assess whether oxygen radicals could directly affect NT and whether excess free radicals generated in stress/depression may affect tissue ascorbate stores. Exam-stressed students and depressed patients were compared respectively to these students at low stress and depressed patients on high antioxidant intakes. In this study, NT correlated positively with tissue ascorbate stores. A range of antioxidants were tested as possible inhibitors of oxy radical interaction with NT using nitroblue tetrazolium reduction to for-mazan with superoxide anion. At physiological plasma concentrations, ascorbate inhibited this reduction but dehydroascorbate, tocopherol, retinol, selenium, urate, and reduced glutathione were ineffective. Superoxide anion directly reduced lymphocytic NT activity and this effect was reversed by either 100 molar ascorbate in vitro or a high antioxidant intake in vivo. In conclusion, the low NT activities and ascorbate stores found in stressed/depressed people appear to be mediated by higher levels of free radicals reported in these subjects. These conclusions are consistent with published reports of (1) normal NT levels in melancholic patients on high antioxidant diets; (2) heightened inflammatory reponses during stress/depression; (3) low serum levels of zinc in depressed patients.     

Relationship between psychological stress and lymphocytic 5′-ectonucleotidase

The relationship between psychological stress and lymphocytic 5-ectonucleotidase, an enzyme marker for lymphocyte differentiation, was studied. Lymphocytic 5-ectonucleotidase was decreased significantly by about twofold in persons experiencing psychological stress, with a corresponding change in Total Mood Disturbance scores of the Profile of Mood States. Enzyme values were reversible in that they returned to normal once the stress had been reduced. Administration of high doses of ascorbate to severely depressed patients also normalized 5-ectonucleotidase activities, and implied that low enzyme values in stressed persons may be mediated by oxygen radical damage. This finding was consistent with previous reports of heightened inflammatory responses occurring in depressed patients. The primary cause of lowered 5-ectonucleotidase during stress may be the breakdown in the homeostatic mechanisms of the hypothalamic-pituitary-adrenal axis and immune system resulting in lymphoid tissue resistance to corticosteroids. It is suggested that this lowering of lymphocyte 5-ectonucleotidase may contribute to stress-mediated immune suppression by inhibiting lymphocyte maturation.     

Facial expression coding in children and adolescents with autism: Reduced adaptability but intact norm-based coding

Individuals with autism spectrum disorder (ASD) can have difficulty recognizing emotional expressions. Here, we asked whether the underlying perceptual coding of expression is disrupted. Typical individuals code expression relative to a perceptual (average) norm that is continuously updated by experience. This adaptability of face-coding mechanisms has been linked to performance on various face tasks. We used an adaptation aftereffect paradigm to characterize expression coding in children and adolescents with autism. We asked whether face expression coding is less adaptable in autism and whether there is any fundamental disruption of norm-based coding. If expression coding is norm-based, then the face aftereffects should increase with adaptor expression strength (distance from the average expression). We observed this pattern in both autistic and typically developing participants, suggesting that norm-based coding is fundamentally intact in autism. Critically, however, expression aftereffects were reduced in the autism group, indicating that expression-coding mechanisms are less readily tuned by experience. Reduced adaptability has also been reported for coding of face identity and gaze direction. Thus, there appears to be a pervasive lack of adaptability in face-coding mechanisms in autism, which could contribute to face processing and broader social difficulties in the disorder.     

Role and group identity and adjustment to the possibility of running group disbandment

Role and group identities are distinct yet related constructs. Both identities may be relevant to exercise yet exercise identity research has focused mostly on exercise role identity.ObjectiveWe examined the relationship between role and group identity among runners. Further, the relationship of runner role and running group identity were examined relative to social cognitive and behavioural outcomes relative to running and the possibility of running group disbandment.DesignAn observational design was used.MethodRunning group members completed measures of runner role and running group identity, self-efficacy for running, and aspects of recent exercise and anticipated reactions to running group disbandment.ResultsRunner role and running group identity showed a small, positive correlation. Runner role identity was associated with self-efficacy for running, vigorous exercise, less group running and adaptive reactions to the possibility of group disbandment. Running group identity was associated with negative self-efficacy, greater percentage of runs being conducted with the group and maladaptive reactions to group disbandment. Runner role and running group identity did not interact in their relationship to exercise-related outcomes.ConclusionsIn the context of running, role and group identities are related but unique variables. Identification as a runner may not only be associated with exercise in the context of the group but may also have protective effects against disruptions to group running. Identification with the running group may compromise exercise in the face of group disbandment.