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Elvira Lopeztamames - One of the best experts on this subject based on the ideXlab platform.

Stefania Vichi - One of the best experts on this subject based on the ideXlab platform.

Nicholas G. Martin - One of the best experts on this subject based on the ideXlab platform.

  • Genetic architecture of subcortical brain regions common and region specific Genetic contributions
    Faculty of Health; Institute of Health and Biomedical Innovation, 2014
    Co-Authors: Narelle K. Hansell, Miguel E Renteria, Lachlan T Strike, Katie L Mcmahon, G I De Zubicaray, Ian B Hickie, Paul M Thompson, Nicholas G. Martin
    Abstract:

    Free to read on publisher website Understanding the aetiology of patterns of variation within and covariation across brain regions is key to advancing our understanding of the functional, anatomical and developmental networks of the brain. Here we applied multivariate twin modelling and principal component analysis (PCA) to investigate the Genetic architecture of the size of seven subcortical regions (caudate nucleus, thalamus, putamen, pallidum, hippocampus, amygdala and nucleus accumbens) in a Genetically informative sample of adolescents and young adults (N=1038; mean age=21.6±3.2years; including 148 monozygotic and 202 dizygotic twin pairs) from the Queensland Twin IMaging (QTIM) study. Our multivariate twin modelling identified a common Genetic Factor that accounts for all the heritability of intracranial volume (0.88) and a substantial proportion of the heritability of all subcortical structures, particularly those of the thalamus (0.71 out of 0.88), pallidum (0.52 out of 0.75) and putamen (0.43 out of 0.89). In addition, we also found substantial region-specific Genetic contributions to the heritability of the hippocampus (0.39 out of 0.79), caudate nucleus (0.46 out of 0.78), amygdala (0.25 out of 0.45) and nucleus accumbens (0.28 out of 0.52). This provides further insight into the extent and organization of subcortical Genetic architecture, which includes developmental and general growth pathways, as well as the functional specialization and maturation trajectories that influence each subcortical region. This multivariate twin study identifies a common Genetic Factor that accounts for all the heritability of intracranial volume (0.88) and a substantial proportion of the heritability of all subcortical structures, particularly those of the thalamus (0.71 out of 0.88), pallidum (0.52 out of 0.75) and putamen (0.43 out of 0.89). In parallel, it also describes substantial region-specific Genetic contributions to the heritability of the hippocampus (0.39 out of 0.79), caudate nucleus (0.46 out of 0.78), amygdala (0.25 out of 0.45) and nucleus accumbens (0.28 out of 0.52).

  • Genetic Influences on Four Measures of Executive Functions and Their Covariation with General Cognitive Ability: The Older Australian Twins Study
    Behavior Genetics, 2012
    Co-Authors: Teresa Lee, Margaret J. Wright, Nicholas G. Martin, Miriam A. Mosing, Julie D. Henry, Julian N. Trollor, David Ames, Perminder S. Sachdev
    Abstract:

    “Executive functions” (EF) is a multidimensional construct which encompasses many higher-order cognitive control operations, and is considered a potential mediator of age-associated changes in other cognitive domains. Here we examine the heritability of four measures of EF, and the Genetic influences on their covariation with general cognitive abilities (GCA) from the Older Australian Twins Study. Participants included 117 pairs of monozygotic twins, 98 pairs of dizygotic twins, and 42 single twins, with a mean age of 71. Genetic modeling showed that additive Genetic Factors contributed to 59, 63, 29, and 31% of the variance in the four measures: working memory, verbal fluency, response inhibition and cognitive flexibility, respectively. The phenotypic associations among the four EF measures were modest, which is in line with other evidence that EF is a multi-dimensional construct. All of the covariation between the EF measures was attributable to a common Genetic Factor. Similarly, all of the covariation between EF and General Cognitive Ability was explained by a common Genetic Factor, with no significant covariance due to environmental (E) Factors. The Genetic correlations between the measures were moderately high, suggesting that they may have common biological underpinnings. The Genetic influence in the covariation of the EF measures and GCA also suggests that some aspects of EF and GCA share the same genes or same set of genes.

  • The perception of quinine taste intensity is associated with common Genetic variants in a bitter receptor cluster on chromosome 12
    Human Molecular Genetics, 2010
    Co-Authors: Danielle R Reed, Gu Zhu, Fujiko F. Duke, Megan J Campbell, Sarah E. Medland, Anjali K Henders, Grant W Montgomery, Nicholas G. Martin, Paul A. S. Breslin, Margaret J. Wright
    Abstract:

    The perceived taste intensities of quinine HCl, caffeine, sucrose octaacetate (SOA) and propylthiouracil (PROP) solutions were examined in 1457 twins and their siblings. Previous heritability modeling of these bitter stimuli indicated a common Genetic Factor for quinine, caffeine and SOA (22-28%), as well as separate specific Genetic Factors for PROP (72%) and quinine (15%). To identify the genes involved, we performed a genome-wide association study with the same sample as the modeling analysis, genotyped for approximately 610,000 single-nucleotide polymorphisms (SNPs). For caffeine and SOA, no SNP association reached a genome-wide statistical criterion. For PROP, the peak association was within TAS2R38 (rs713598, A49P, P = 1.6 × 10(-104)), which accounted for 45.9% of the trait variance. For quinine, the peak association was centered in a region that contains bitter receptor as well as salivary protein genes and explained 5.8% of the trait variance (TAS2R19, rs10772420, R299C, P = 1.8 × 10(-15)). We confirmed this association in a replication sample of twins of similar ancestry (P = 0.00001). The specific Genetic Factor for the perceived intensity of PROP was identified as the gene previously implicated in this trait (TAS2R38). For quinine, one or more bitter receptor or salivary proline-rich protein genes on chromosome 12 have alleles which affect its perception but tight linkage among very similar genes precludes the identification of a single causal Genetic variant.

  • Genetic covariation among facets of openness to experience and general cognitive ability
    Twin Research and Human Genetics, 2008
    Co-Authors: Mark A Wainwright, Margaret J. Wright, Michelle Luciano, G M Geffen, Nicholas G. Martin
    Abstract:

    Genetic and environmental sources of covariation among cognitive measures of verbal IQ, performance IQ (PIQ), academic achievement, 2-choice reaction time (CRT), inspection time (IT) and the 6 Openness facets of the NEO Personality Inventory-Revised (NEO PI-R) were examined. The number of twin and twin–sibling pairs ranged from 432 (182 MZ, 350 DZ/sibling) to 1023 (273 MZ, 750 DZ/sibling) for cognitive measures, and between 432 (90 MZ, 342 DZ/sibling) — 437 (91 MZ, 346 DZ/sibling) for Openness facets. Structural equation modeling best supported a model with a 3-Factor additive Genetic structure. A Genetic general Factor subsumed the 5 cognitive measures and 5 of the 6 Openness facets (Actions did not load significantly). A second additive Genetic Factor incorporated the 6 Openness facets, and a third additive Genetic Factor incorporated the 5 cognitive measures. Specific additive and dominance Genetic effects were also evident, as were shared common and shared unique environmental influences, and specific unique environmental effects. The Openness facets of Ideas and Values evidenced the strongest phenotypic correlations with cognitive indices, particularly verbal measures. The Genetic correlations among Openness facets and cognitive measures ranged from −.06 to .79. Results were interpreted as suggesting that Openness is related to general cognitive ability (g) through a Genetic mechanism and that gengenders a minor but discernable disposition towards Openness for the majority of facets.

  • a Genetic investigation of the covariation among inspection time choice reaction time and iq subtest scores
    Behavior Genetics, 2004
    Co-Authors: Michelle Luciano, Margaret J. Wright, Glen A. Smith, G M Geffen, L B Geffen, Nicholas G. Martin
    Abstract:

    Information processing speed, as measured by elementary cognitive tasks, is correlated with higher order cognitive ability so that increased speed relates to improved cognitive performance. The question of whether the Genetic variation in Inspection Time (IT) and Choice Reaction Time (CRT) is associated with IQ through a unitary Factor was addressed in this multivariate Genetic study of IT, CRT, and IQ subtest scores. The sample included 184 MZ and 206 DZ twin pairs with a mean age of 16.2 years (range 15-18 years). They were administered a visual (pi-figure) IT task, a two-choice RT task, five computerized subtests of the Multidimensional Aptitude Battery, and the digit symbol substitution subtest from the WAIS-R. The data supported a Factor model comprising a general, three group (verbal ability, visuospatial ability, broad speediness), and specific Genetic Factor structure, a shared environmental Factor influencing all tests but IT, plus unique environmental Factors that were largely specific to individual measures. The general Genetic Factor displayed Factor loadings ranging between 0.35 and 0.66 for the IQ subtests, with IT and CRT loadings of -0.47 and -0.24, respectively. Results indicate that a unitary Factor is insufficient to describe the entire relationship between cognitive speed measures and all IQ subtests, with independent Genetic effects explaining further covariation between processing speed (especially CRT) and Digit Symbol.

Margaret J. Wright - One of the best experts on this subject based on the ideXlab platform.

  • Genetic Influences on Four Measures of Executive Functions and Their Covariation with General Cognitive Ability: The Older Australian Twins Study
    Behavior Genetics, 2012
    Co-Authors: Teresa Lee, Margaret J. Wright, Nicholas G. Martin, Miriam A. Mosing, Julie D. Henry, Julian N. Trollor, David Ames, Perminder S. Sachdev
    Abstract:

    “Executive functions” (EF) is a multidimensional construct which encompasses many higher-order cognitive control operations, and is considered a potential mediator of age-associated changes in other cognitive domains. Here we examine the heritability of four measures of EF, and the Genetic influences on their covariation with general cognitive abilities (GCA) from the Older Australian Twins Study. Participants included 117 pairs of monozygotic twins, 98 pairs of dizygotic twins, and 42 single twins, with a mean age of 71. Genetic modeling showed that additive Genetic Factors contributed to 59, 63, 29, and 31% of the variance in the four measures: working memory, verbal fluency, response inhibition and cognitive flexibility, respectively. The phenotypic associations among the four EF measures were modest, which is in line with other evidence that EF is a multi-dimensional construct. All of the covariation between the EF measures was attributable to a common Genetic Factor. Similarly, all of the covariation between EF and General Cognitive Ability was explained by a common Genetic Factor, with no significant covariance due to environmental (E) Factors. The Genetic correlations between the measures were moderately high, suggesting that they may have common biological underpinnings. The Genetic influence in the covariation of the EF measures and GCA also suggests that some aspects of EF and GCA share the same genes or same set of genes.

  • The perception of quinine taste intensity is associated with common Genetic variants in a bitter receptor cluster on chromosome 12
    Human Molecular Genetics, 2010
    Co-Authors: Danielle R Reed, Gu Zhu, Fujiko F. Duke, Megan J Campbell, Sarah E. Medland, Anjali K Henders, Grant W Montgomery, Nicholas G. Martin, Paul A. S. Breslin, Margaret J. Wright
    Abstract:

    The perceived taste intensities of quinine HCl, caffeine, sucrose octaacetate (SOA) and propylthiouracil (PROP) solutions were examined in 1457 twins and their siblings. Previous heritability modeling of these bitter stimuli indicated a common Genetic Factor for quinine, caffeine and SOA (22-28%), as well as separate specific Genetic Factors for PROP (72%) and quinine (15%). To identify the genes involved, we performed a genome-wide association study with the same sample as the modeling analysis, genotyped for approximately 610,000 single-nucleotide polymorphisms (SNPs). For caffeine and SOA, no SNP association reached a genome-wide statistical criterion. For PROP, the peak association was within TAS2R38 (rs713598, A49P, P = 1.6 × 10(-104)), which accounted for 45.9% of the trait variance. For quinine, the peak association was centered in a region that contains bitter receptor as well as salivary protein genes and explained 5.8% of the trait variance (TAS2R19, rs10772420, R299C, P = 1.8 × 10(-15)). We confirmed this association in a replication sample of twins of similar ancestry (P = 0.00001). The specific Genetic Factor for the perceived intensity of PROP was identified as the gene previously implicated in this trait (TAS2R38). For quinine, one or more bitter receptor or salivary proline-rich protein genes on chromosome 12 have alleles which affect its perception but tight linkage among very similar genes precludes the identification of a single causal Genetic variant.

  • Genetic covariation among facets of openness to experience and general cognitive ability
    Twin Research and Human Genetics, 2008
    Co-Authors: Mark A Wainwright, Margaret J. Wright, Michelle Luciano, G M Geffen, Nicholas G. Martin
    Abstract:

    Genetic and environmental sources of covariation among cognitive measures of verbal IQ, performance IQ (PIQ), academic achievement, 2-choice reaction time (CRT), inspection time (IT) and the 6 Openness facets of the NEO Personality Inventory-Revised (NEO PI-R) were examined. The number of twin and twin–sibling pairs ranged from 432 (182 MZ, 350 DZ/sibling) to 1023 (273 MZ, 750 DZ/sibling) for cognitive measures, and between 432 (90 MZ, 342 DZ/sibling) — 437 (91 MZ, 346 DZ/sibling) for Openness facets. Structural equation modeling best supported a model with a 3-Factor additive Genetic structure. A Genetic general Factor subsumed the 5 cognitive measures and 5 of the 6 Openness facets (Actions did not load significantly). A second additive Genetic Factor incorporated the 6 Openness facets, and a third additive Genetic Factor incorporated the 5 cognitive measures. Specific additive and dominance Genetic effects were also evident, as were shared common and shared unique environmental influences, and specific unique environmental effects. The Openness facets of Ideas and Values evidenced the strongest phenotypic correlations with cognitive indices, particularly verbal measures. The Genetic correlations among Openness facets and cognitive measures ranged from −.06 to .79. Results were interpreted as suggesting that Openness is related to general cognitive ability (g) through a Genetic mechanism and that gengenders a minor but discernable disposition towards Openness for the majority of facets.

  • a Genetic investigation of the covariation among inspection time choice reaction time and iq subtest scores
    Behavior Genetics, 2004
    Co-Authors: Michelle Luciano, Margaret J. Wright, Glen A. Smith, G M Geffen, L B Geffen, Nicholas G. Martin
    Abstract:

    Information processing speed, as measured by elementary cognitive tasks, is correlated with higher order cognitive ability so that increased speed relates to improved cognitive performance. The question of whether the Genetic variation in Inspection Time (IT) and Choice Reaction Time (CRT) is associated with IQ through a unitary Factor was addressed in this multivariate Genetic study of IT, CRT, and IQ subtest scores. The sample included 184 MZ and 206 DZ twin pairs with a mean age of 16.2 years (range 15-18 years). They were administered a visual (pi-figure) IT task, a two-choice RT task, five computerized subtests of the Multidimensional Aptitude Battery, and the digit symbol substitution subtest from the WAIS-R. The data supported a Factor model comprising a general, three group (verbal ability, visuospatial ability, broad speediness), and specific Genetic Factor structure, a shared environmental Factor influencing all tests but IT, plus unique environmental Factors that were largely specific to individual measures. The general Genetic Factor displayed Factor loadings ranging between 0.35 and 0.66 for the IQ subtests, with IT and CRT loadings of -0.47 and -0.24, respectively. Results indicate that a unitary Factor is insufficient to describe the entire relationship between cognitive speed measures and all IQ subtests, with independent Genetic effects explaining further covariation between processing speed (especially CRT) and Digit Symbol.

  • Genetic influence on the variance in P3 amplitude and latency
    Behavior Genetics, 2001
    Co-Authors: Margaret J. Wright, Narelle K. Hansell, Gina M. Geffen, Laurie B. Geffen, Glen A. Smith, Nicholas G. Martin
    Abstract:

    The P3(00) event-related potential (ERP) component is widely used as a measure of cognitive functioning and provides a sensitive electrophysiological index of the attentional and working memory demands of a task. This study investigated what proportion of the variance in the amplitude and latency of the P3, elicited in a delayed response working memory task, could be attributed to Genetic Factors. In 335 adolescent twin pairs and 48 siblings, the amplitude and latency of the P3 were examined at frontal, central, and parietal sites. Additive Genetic Factors accounted for 48% to 61% of the variance in P3 amplitude. Approximately one-third of the Genetic variation at frontal sites was mediated by a common Genetic Factor that also influenced the Genetic variation at parietal and central sites. Familial resemblance in P3 latency was due to Genetic influence that accounted for 44% to 50% of the variance. Genetic covariance in P3 latency across sites was substantial, with a large part of the variance found at parietal, central, and frontal sites attributed to a common Genetic Factor. The findings provide further evidence that the P3 is a promising phenotype of neural activity of the brain and has the potential to be used in linkage and association analysis in the search for quantitative trait loci (QTLs) influencing cognition.

Lorena Pizzale - One of the best experts on this subject based on the ideXlab platform.