Biomedical subjects

L A Thompson

Publications and source records attributed to L A Thompson.

At least 19 recordsLinked to original sources

PubMed1995

The genetic and environmental variance underlying elementary cognitive tasks.

Although previous studies have examined the genetic and environmental influences upon general intelligence and specific cognitive abilities in school-age children, few studies have examined elementary cognitive tasks in this population. The current study included 149 MZ and 138 same-sex DZ twin pairs who participated in the Western Reserve Twin Project. Thirty measures from the Cognitive Abilities Test (CAT; Detterman, 1986) were studied. Results indicate that (1) these measures are reliable indicators of general intelligence in children and (2) the structure of genetic and environmental influences varies across measures. These results not only indicate that elementary cognitive tasks display heterogeneous genetic and environmental effects, but also may demonstrate that individual differences in biologically based processes are not necessarily due to genetic variance.

Adolescent↗

PubMed1995

Encoding and memory for visible speech and gestures: a comparison between young and older adults.

Two experiments explored whether older adults have developed a strategy of compensating for slower speeds of language processing and hearing loss by relying more on the visual modality. Experiment 1 examined the influence of visual articulatory movements of the face (visible speech) in auditory-visual syllable classification in young adults and older adults. Older adults showed a significantly greater influence of visible speech. Experiment 2 examined immediate recall in three spoken-language sentence conditions: speech alone, with visible speech, or with both visible speech and iconic gestures. Sentences also varied in meaningfulness and speech rate. In the old adult group, recall was better for sentences containing visible speech compared with the speech-alone sentences in the meaningful sentence condition. Old adults' recall showed no overall benefit of the presence of gestures. Young adults' recall on meaningful sentences was not higher for the visible speech compared with the speech-alone condition, whereas recall was significantly higher with the addition of iconic gestures. In the anomalous sentence condition, both young and old adults showed an advantage in recall by the presence of visible speech. The experiments provide converging evidence for old adults' greater reliance on visible speech while processing visual-spoken language.

Adolescent↗

PubMed1995

Current attitudes towards egg donation among men and women.

Recent widespread concern has led to legislation in the UK preventing the use of fetal ovarian tissue for the treatment of infertile women. This questionnaire-based study aimed to assess the attitudes of both fertile and infertile men and women as well as egg donors and recipients towards the use of donated eggs for treatment, diagnosis and research. Fertile individuals were significantly less aware of egg donation but the majority in both the fertile and the infertile groups approved the use of eggs for research (89 and 95% of women and 88 and 92% of men respectively) and treatment (similar percentages). However, fetal sources of oocytes were acceptable to only 15% of women in the fertile, 21% in the infertile, 35% in the recipient and 19% in the donor groups. Cadaveric sources of oocytes were slightly more acceptable (28% fertile, 28% infertile, 50% recipient and 42% donors). Both these sources of oocytes were slightly more acceptable to men. Education had little influence on attitudes, although men and women of tertiary education level said they would be less likely to have gamete donation themselves. Thus there would appear to be widespread approval for the use of donor eggs in research and treatment but not if the source of eggs is fetal or cadaveric.

Aborted Fetus↗

PubMed1995

A comparison of the effects of different biopsy strategies on the post-thaw survival of 8-cell-stage mouse embryos: implications for preimplantation diagnosis.

The aim of this study was to investigate the effects of two different biopsy strategies, zona slitting and zona piercing, on the post-thaw survival and subsequent in-vitro development of 8-cell mouse embryos. From control experiments it was determined that neither biopsy by zona slitting nor zona piercing adversely affected embryo development in vitro, as similar rates of blastocyst formation and hatching were found between biopsied and zona-intact embryos; there was, however, a trend towards a lower rate of blastocyst hatching in embryos biopsied by zona piercing (78.3% compared with 91.9% of zona-intact embryos). When biopsy was followed by cryopreservation a different picture was seen: similar rates of freeze-thaw survival were found for zona-slit, zona-pierced and zona-intact embryos (84.2, 88.5 and 87.2% respectively), but this was superseded by a significant (P < 0.05) reduction in the blastocyst formation rates (61.4% zona-slit and 63.9% zona-pierced versus 78.7% zona-intact) and hatching rates (51% zona-slit and 52.5% zona-pierced versus 72.3% zona-intact) of the biopsied embryos. When the effects of zona slitting and piercing were considered in isolation, i.e. without performing biopsy, it was found that the larger holes produced by zona slitting rendered embryos more susceptible to freeze-thaw damage.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1995

A twin study of competence and problem behavior in childhood and early adolescence.

The Child Behavior Checklist (CBCL) was completed by parents of 181 pairs of same-sex twins ages 7-15 (mean age = 11.0 years). Correlations between scores on the CBCL scales for 99 pairs of monozygotic twins and 82 pairs of dizygotic twins indicated significant genetic influences that varied according to the specific area of competence and problem behavior. Model-fitting estimates derived from multiple regression analyses indicated significant genetic influence on competence in school and on all areas of problem behavior. In addition, significant shared environmental influence was detected for amount and quality of participation in activities, quality of social relationships, performance in school, anxiety/depression, and delinquent behaviour. Implications for future work on the mechanisms underlying these effects are discussed.

Adolescent↗

PubMed1994

Intracellularly recorded response of rat striatal neurons in vitro to fenoldopam and SKF 38393 following lesions of midbrain dopamine cells.

The effect of long-term (6-19 weeks) 6-hydroxydopamine-induced (6-OHDA) lesions of midbrain dopamine cells on dopamine D1-like agonist-induced changes in the excitability of rat striatal neurons was investigated in vitro using tissue slices and intracellular recording techniques. Fenoldopam and (+/-)-SKF 38393 predominantly decreased excitability in control preparations including striatal neurons located contralateral to 6-OHDA injection sites and neurons obtained from rats receiving sham injections or no treatment. Fenoldopam also inhibited neurons ipsilateral to lesions of midbrain dopamine cells. (+/-)-SKF 38393, unlike fenoldopam, produced predominantly increases in the excitability of ipsilateral striatal neurons. Superfusion of the D1 receptor antagonist, SCH 23390, blocked fenoldopam-induced decreases in excitability but not the (+/-)-SKF 38393-induced excitation of neurons ipsilateral to the lesion. Sequential application of fenoldopam and quinpirole, a D2/D3 receptor agonist, produced responses to both drugs in a majority of neurons. The results demonstrate that inhibitory responses to fenoldopam are mediated by D1 receptors, while excitatory effects of (+/-)-SKF 38393 in the striatum ipsilateral to the lesion are apparently not dependent on D1 receptor activation. These findings also suggest that dopamine D1 and D2/D3 receptors are able to concurrently influence the excitability of striatal neurons in the dopamine deafferentated striatum. Similar regulation of striatal neurons in vivo may contribute to dopaminergic regulation of basal ganglia output and the ability of dopaminomimetic agents to ameliorate symptoms of dopaminergic deficiency in Parkinson's disease.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗

PubMed1994

Children's integration of speech and pointing gestures in comprehension.

We examined 4- and 9-year-old's referential comprehension when given pointing gestures and spoken labels, in two types of contextually ambiguous situations. In one situation, speech/gesture discordance was produced in conditions where labels for one of four objects being referred to sounded either alike, or different from each other. In the other, the contextual set contained the same two objects, and ambiguity was produced by factorially combining speech on a continuum ranging between /bcl/ and /dcl/ with a pointing gesture from a continuum ranging between an unambiguous point to a ball and to a doll. Results showed that the speech modality had a far greater influence on word comprehension than gestures. Second, the influence of gestures was greater for the older children. Mathematical models of speech-gesture understanding were tested against the data. Selection models assume that one dimension of information is used on a given trial, and that the selection of a modality depends on the ambiguity of information encoded on the dominant dimension. The Fuzzy Logical Model of Perception (FLMP) assumes that both modalities are evaluated independently of one another and then integrated to achieve comprehension. The results from both age groups were best described by the assumptions of the FLMP. Results are related to general claims about perceptual development during childhood concerning the quality of representations formed and dimensional selectivity of visual-spoken language.

Auditory Perception↗

PubMed1994

DNA markers associated with high versus low IQ: the IQ Quantitative Trait Loci (QTL) Project.

General cognitive ability (intelligence, often indexed by IQ scores) is one of the most highly heritable behavioral dimensions. In an attempt to identify some of the many genes (quantitative trait loci; QTL) responsible for the substantial heritability of this quantitative trait, the IQ QTL Project uses an allelic association strategy. Allelic frequencies are compared for the high and low extremes of the IQ dimension using DNA markers in or near genes that are likely to be relevant to neural functioning. Permanent cell lines have been established for low-IQ (mean IQ = 82; N = 18), middle-IQ (mean IQ = 105; N = 21), and high-IQ (mean IQ = 130; N = 24) groups and for a replication sample consisting of even more extreme low-IQ (mean IQ = 59; N = 17) and high-IQ (mean IQ = 142; N = 27) groups. Subjects are Caucasian children tested from 6 to 12 years of age. This first report of the IQ QTL Project presents allelic association results for 46 two-allele markers and for 26 comparisons for 14 multiple-allele markers. Two markers yielded significant (p < .01) allelic frequency differences between the high- and the low-IQ groups in the combined sample-a new HLA marker for a gene unique to the human species and a new brain-expressed triplet repeat marker (CTGB33). The prospects for harnessing the power of molecular genetic techniques to identify QTL for quantitative dimensions of human behavior are discussed.

Alleles↗

PubMed1994

The heritability of memory in the Western Reserve Twin Project.

The heritability of memory ability was examined using 137 monozygotic and 127 same-sex dizygotic twin pairs from the Western Reserve Twin Project. Memory was assessed by eight measures drawn from the following batteries: the Wechsler Intelligence Scale for Children--Revised, the Colorado Test of Specific Cognitive Abilities, and the Cognitive Abilities Test. The results indicate that phenotypic correlations are generally low across these memory measures and heritability varies as a function of memory measure. These findings suggest that the heritability of memory varies as a function of the memory measure employed. Therefore, future studies investigating heritability estimates of memory should use a multimeasure battery to study this construct.

Adolescent↗

PubMed1994

Dimensional strategies dominate perceptual classification.

The nature of perceptual classification was investigated in children ranging between 4 and 10 years, and in young adults. Triad classification task responses were categorized as consistent or inconsistent with several classification rules, including: overall-similarity, size-dimensional, brightness-dimensional, pure identity, and all combinations of a switch from one rule to another midway through the experiment. The rule with the highest proportion of responses consistent with it reflected each person's best-fitting rule pattern. The higher this value, the higher the assumed consistency of rule usage. Data from the majority of individuals in every age group conformed best to one of the three dimensional rules. In addition, the consistency values for individuals' best-fitting rule became significantly higher as age increased. It is concluded that most children have a tendency to attend selectively to one stimulus dimension when making perceptual classification judgments. The developmental trend in perceptual classification does not appear to be a holistic-to-analytic shift; instead, it is a trend toward greater consistency in following a given classification rule.

Adult↗

PubMed1993

Genetics and high cognitive ability.

More is known about the genetics of general cognitive ability (g) than any other trait in psychology. Recent findings on the genetics of g include the following three examples: (1) heritability increases throughout the lifespan; (2) heritabilities of performance in cognitive tests are strongly correlated with the tests' loadings on a g factor; and (3) genetic effects on scholastic achievement largely overlap with genetic effects on cognitive ability. This body of genetic research addresses the aetiology of individual differences in the normal range. Much less is known about the genetics of the high end of the distribution. Finding heritability in the normal range of cognitive ability does not imply that high ability is also genetic in origin. However, the first twin study of high IQ children, which uses a new technique that analyses the average difference between extreme groups and the rest of the population, suggests that high IQ is as heritable as individual differences in the normal range. We are currently engaged in a molecular genetic study that attempts to identify specific genes that contribute to high ability.

Adolescent↗

PubMed1993

Differences in heritability across groups differing in ability, revisited.

Three recent studies have used twin data to explore the possibility of differential contributions of heritability and environmentality to individual differences in cognitive ability as a function of ability level (Detterman, D. K., et al., Behav. Genet. 20:369-384; 1990; Bailey, M. J. and Revelle, W., Behav. Genet. 21:397-404, 1991; Cherny, S. S., et al., Behav. Genet. 22:153-162, 1992). All arrived at different conclusions: higher heritability at the low end, higher heritability at the high end, and no differential influence, respectively. The current report involves a sample of 148 identical and 135 fraternal twin pairs from the Western Twin Project who were tested on a battery of intelligence and achievement tests to further explore the issue. The results suggest no significant differences in heritability at either the high or the low end, although a trend toward higher heritability for children of higher ability is evident. Individual differences for a composite ability/achievement score showed significantly greater influence of shared family environment at the low end than the rest of the distribution. In general, results for cognitive ability and academic achievement were highly similar.

Adolescent↗

PubMed1993

The phenotypic and genetic relationships among measures of cognitive ability, temperament, and scholastic achievement.

The covariance among measures of cognitive ability, temperament, and scholastic achievement was examined in a subsample of 326 (89 Monozygotic, 74 Dizygotic) twins drawn from the Western Reserve Twin Project. Both phenotypic and behavioral genetic models were fit to the data. Univariate analyses indicate significant genetic influences on cognitive, achievement, and temperament variables. Common environmental influences also affected cognition and achievement but not temperament. Multivariate analyses indicate that both genetic and common environmental influences contribute to the covariance among all three variables. Cognition and achievement are highly genetically correlated. In contrast, achievement and temperament are highly correlated for common environmentality, while cognition and temperament are not.

Adolescent↗

PubMed1992

Involvement of the nigrotectal and nigrothalamic pathways in kappa opioid-induced circling.

The relationship between kappa opioid-induced movement and output stations of the substantia nigra pars reticulata (SNpr) was examined using the rodent circling model. Contralateral rotation produced by intranigral microinjection of the kappa opiate U50,488 was lower in animals with ibotenic acid lesions of either the ipsilateral ventromedial thalamus or superior colliculus than in control animals without lesions. These results suggest that endogenous kappa opioids in the SNpr may influence movement through actions on the nigrothalamic and nigrotectal pathways. In contrast, animals with ipsilateral lesions of the striatum showed an increase in circling relative to controls, possibly due to kappa receptor supersensitivity in the SNpr.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗

PubMed1992

Comparison of glutamine synthetases from brains of genetically epilepsy prone and genetically epilepsy resistant rats.

Since glutamine synthetase (GS) has been proposed as the primary enzyme in the regulation of glutamate metabolism in the central nervous system and since inhibition of the activity of this enzyme in vivo leads to seizures, it has been proposed that an abnormality in the structure or function of this enzyme could be responsible for the induction of seizures in epilepsy prone rats. To test this hypothesis the glutamine synthetases were purified from the brains of both genetically epilepsy prone rats (GEPR) and their progenitors, genetically epilepsy resistant rats (GERR). The enzymes were compared using both SDS-PAGE and isoelectric focusing. The immunoreactivities of equal amounts of protein were determined using the ELISA technique, and the regulation of the glutamine synthetase activities by Mn2+/Mg2+ ratios were compared. The only difference found between the glutamine synthetases from the two strains was a slightly lower specific activity of the enzyme from the epilepsy prone animals.

Animals↗

PubMed1992

A study of developmental speech and language disorders in twins.

Fifty-seven same-sex twin sets (32 monozygotic and 25 dizygotic) were examined for concordance of speech and language disorders. Results showed monozygotic twins to have higher concordance than dizygotic twins. In addition, monozygotic twins were more similar in the types of disorders they presented than dizygotic twins. Positive family histories for speech, language, and learning disorders were reported in the nuclear families of the twins.

Child↗

PubMed1992

The leukocytic reaction of the human uterine cervix.

PROBLEM: Sperm interaction with the immune system of the human cervix is poorly understood. METHOD: The leukocytic response of the human cervix to sperm was examined in a closely monitored patient population (N = 10), using monoclonal antibody cell identification techniques. Baseline data were collected from both cervical mucus and smears sampled before treatment by donor insemination. Donor insemination was timed to coincide with ovulation by monitoring plasma LH concentrations twice daily. Following insemination the numbers of leukocytes were recorded in cervical mucus and smear samples taken over a 24-h period relative to the time of treatment. Controls treated with "pure sperm," seminal plasma, cryopreservative, and cervical smearing alone were also included in the study. RESULTS: Only those women treated with sperm cells exhibited substantial elevations in leukocyte numbers following inseminations. Additionally, serial cervical smearing induced an inflammatory response of the cervix. In all the women, the neutrophil was the predominant leukocyte of the cervix both during the baseline and treatment periods (median values ranged from 77 to 86%). Macrophages, T-helper lymphocytes, and T-suppressor lymphocytes were also detected, but only in low numbers (2-10.6%). Two patients and one control ("pure sperm") became pregnant during their study cycle. CONCLUSIONS: We conclude that the leukocytic reaction is a physiological response of the cervix to sperm, the function of which remains to be established.

Cell Movement↗

PubMed1991

Evidence for intrinsic expression of enkephalin-like immunoreactivity and opioid binding sites in cat superior colliculus.

We have investigated the cellular localization of opioid peptides and binding sites in the cat's superior colliculus by testing the effects of retinal deafferentation and intracollicular excitotoxin lesions on patterns of enkephalin-like immunostaining and opiate receptor ligand binding. In normal cats, enkephalin-like immunoreactivity marks a thin tier in the most dorsal stratum griseum superficiale, small neurons of the stratum griseum superficiale, and patches of fibers in the intermediate and deeper gray layers. Eliminating crossed retinotectal afferents by contralateral eye enucleation had little immediate effect on this pattern, although chronic eye enucleation from birth did reduce immunoreactivity in the superficial layers. By contrast, fiber-sparing destruction of collicular neurons by the excitotoxins N-methyl-D-aspartate and ibotenic acid virtually eliminated enkephalin-like immunoreactivity in the neuropil of the upper stratum griseum superficiale, presumably by killing enkephalinergic cells of the superficial layers. Such lesions did not eliminate the patches of enkephalin-like immunoreactivity in the deeper layers. In normal cats, opiate receptor ligand binding is dense in the stratum griseum superficiale, particularly in its upper tier, and moderately dense in the intermediate gray layer. Contralateral eye removal had no detectable effect on the binding pattern, but excitotoxin lesions of the colliculus dramatically reduced binding in both superficial and deep layers. Some ligand binding, including part of that in the upper stratum griseum superficiale, apparently survived such lesions. Similar effects were observed in the lateral geniculate nucleus: enucleation produced no change in binding, whereas excitotoxin lesions greatly reduced specific opiate binding. We conclude that in the superficial collicular layers, both enkephalin-like opioid peptides and their membrane receptors are largely expressed by neurons of intrinsic collicular origin. The close correspondence between the location of these intrinsic opioid elements and the tier of retinal afferents terminating in the upper stratum griseum superficiale further suggests that opiatergic interneurons may modulate retinotectal transmission postsynaptically.

Animals↗