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Biomedical subjects

D W Fulker

Publications and source records attributed to D W Fulker.

At least 91 records · Page 5Linked to original sources
PubMed1984

Preliminary findings from a study of the effects of a challenge dose of alcohol in male twins.

Twelve pairs of MZ and 7 of DZ normal adult male twins were given a challenge dose of 0.8 mg ethanol per kg body weight diluted to a 30% v/v solution. Measures of blood alcohol, mood, craving for alcohol, body sway, heart rate and four psychomotor tasks were taken before, during and after intoxication. Genetic factors were found to be involved in the response of heart rate, body sway and two of the psychomotor tasks, but not in changes in blood alcohol, alertness or craving for alcohol. Drinking habits did not exert a strong influence upon acute responses to alcohol, but were significantly related to craving for alcohol whilst intoxicated.

Adult↗
PubMed1984

Altruism and genetics.

Three questionnaires measuring altruistic tendencies were completed by 573 adult twin pairs from the University of London Institute of Psychiatry Volunteer Twin Register. The questionnaires consisted of a 20-item Self-Report Altruism Scale, a 33-item Empathy Scale, and a 16-item Nurturance Scale, all of which had previously been shown to have construct validity. For the three scales, the intra-class correlations for the 296 MZ pairs were 0.53, 0.54, and 0.49, and for the 179 same-sex DZ pairs were 0.25, 020, and 0.14, giving rough estimates of broad heritability of 56%, 68%, and 72%, respectively. Maximum-likelihood model-fitting revealed about 50% of the variance on each scale to be associated with genetic effects, virtually 0% to be due to the twins' common environment, and the remaining 50% to be due to each twins' specific environment and/or error associated with the test.

Adult↗
PubMed1984

A bivariate path analysis of fear data on twins and their parents.

A simple path model applicable to twins and their parents and involving both cultural and genetic transmission in the presence of phenotypic assortative mating was extended to cover the bivariate case. The model allows for cross assortative mating as well as cross cultural transmission. It was applied to two correlated measures derived from a fear survey questionnaire given to 1000 subjects. In allowing for the impact of more than one variable, the model allows for a much more realistic picture of cultural transmission than provided by the univariate model. The logic of the model and an application are outlined. (The authors are indebted to Professor R.J. Rose for providing the illustrative data.)

Environment↗
PubMed1984

Genetic and environmental influences on obsessional traits and symptoms.

A biometrical genetic analysis was carried out on the response of 419 pairs of twins to the 42-item version of Leyton Obsessional Inventory. Just under half the variation in both the Obsessional Trait and Symptom Scales was due to heredity. Multivariate analysis revealed a genetic effect on the development of obsessional personality and also the transmission of a general tendency predisposing to neurotic breakdown. Although the influence of heredity was outweighed by that of the environment, the latter effect showed an absence of general factors and, in particular, of any noticeable effect from the common home environment.

Diseases in Twins↗
PubMed1983

Genetic architecture of olfactory discriminative avoidance conditioning in Drosophila melanogaster.

Recent claims to have demonstrated associative learning ability in Drosophila melanogaster raise questions about the adaptive significance of behavioral modifiability of this species. In a strain survey and a 9 X 9 half diallel cross study of olfactory discriminative avoidance conditioning, a low narrow heritability and strong directional dominance or heterosis controlling nonrandom phenotypic variation were found. Furthermore, the predicted inbreeding depression and asymmetrical response to bidirectional genetic selection were both observed. The genetic architecture revealed in these experiments is consistent with a close association between this conditioning phenotype and evolutionary fitness. Predictions from this interpretation to the nature of new mutations have been confirmed, and a possible role for conditioning in courtship behavior has been identified.

Animals↗
PubMed1983

Longitudinal stability of cognitive ability in the Colorado Adoption Project.

Measures of general cognitive ability in 1- and 2-year-old adopted and nonadopted infants and their parents were subjected to path analysis to estimate the contribution of genetic and environmental factors to short-term stability. Although significant genetic influences were found at both 1 and 2 years of age, no significant environmental influences shared by parents and children were observed at these ages. Short-term stability of mental ability between the 2 ages was relatively independent of both between-family genetic and environmental influences. However, genetic factors may contribute importantly to long-term stability.

Adoption↗
PubMed1981

Twin-family studies of perceptual speed ability. II. Parameter estimation.

Offspring of monozygotic (MZ) twins form half-ships that permit a direct test of maternal effects and differentiate several sources of between-family environmental variance. Combined with conventional twin data, these genetic half-sibships provide a unique data set for estimating sources of variation in quantitative traits. To illustrate, genetic and environmental parameters were estimated for Identical Pictures Test data obtained from children of MZ twin parents and an (approximate) age-matched cohort of like-sex twins. Analyses of variance of the data, standardized for age and sex, yield 12 mean squares to which gene-environment models were fit. Maximum-likelihood estimation revealed a complete absence of maternal influences and shared environmental effects; a simple two-parameter model, assuming random mating and attributing variation in test scores to additive genes and within-family environment, adequately accounts for the familial data.

Adolescent↗
PubMed1981

Genetics of escape-avoidance conditioning in laboratory and wild populations of rats: a biometrical approach.

The interest of biometrical geneticists in the genetic architecture of behavior is explained with reference to the additive, dominance, and epistatic components of variation and their relation to evolutionary pressures. For one phenotype, escape-avoidance conditioning in Rattus norvegicus, a fairly complete description of its genetic architecture has been gradually built and the major conclusions from four studies of this phenotype are reported: a selection study initially demonstrated the presence of large amounts of additive genetic variation and produced phenotypically extreme lines needed for later work; a diallel cross provided the opportunity for detailed examination of the dominance effects; a triple test cross permitted a similar examination of epistatic effects; and finally, another triple test cross using wild rats provided a confirmatory first attempt to test the assumption that a wild population's genetic architecture did not differ markedly from that found in laboratory populations. In relating the genetic findings to the evolutionary significance of behaviors in the escape-avoidance paradigm, it is argued that interspecific comparisons might play a major role.

Animals↗
PubMed1981

Analysis of two-way escape-avoidance conditioning measures from a diallel cross of eight strains of rats.

In a study designed to investigate genotype-environment interaction, eight strains of laboratory rats were crossbred in a replicated diallel cross employing infantile stimulation and its absence as environmental treatments. This paper reports on measures of the acquisition of two-way escape-avoidance conditioning, comprising number of avoidances, avoidance and escape latencies, and intertrial and presessional crossings, which were subjected to biometrical genetical analysis, all but the last successfully. Additive variation was prominent throughout and some measures showed directional dominance. Effects of stimulation were seen in avoidance number and crossings. The analysis of avoidances by successive blocks of trials using covariance:variance graphs revealed differences in the way the strains varied with respect to the changing relationships of proportions of dominant and recessive alleles governing this behavior. The results are discussed in the light of previous data and of their evolutionary implications.

Animals↗