Navegando por Assunto "Lateralidade cerebral"

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Padrões de dominância manual, podálica e performance motora em gêmeos
(Universidade Federal do Pará, 2011-06-27) HORA, Ana Flávia Lima Teles da; MARTIN, William Lee Berdel; http://lattes.cnpq.br/8591034699611752
The twin method involves analyses of MZ-DZ differences in order to ascertain the proportion of variance in a given trait attributable to genetic and environmental effects. Being genetically identical, MZ twins tend to show high concordance rates for many behavioral attributes, whereas DZs, having about 50% of their genetic configuration in common, should manifest a reduced degree of concordance. However, researchers investigating possible genetic mechanisms underlying the development of cerebral dominance for handedness have not found the twin method to be useful, because in all of the twin-handedness studies since 1924, the discordance rates for left- and right-handedness are similar for MZs and DZs. Furthermore, twins often show a higher prevalence of left-handedness than singletons. Rather than a concern with hereditability, the purpose of this study was to investigate possible differences between right- and left-handed twins (MZs and DZs combined) and singletons on specific phenotypic variables related to handedness, including: footedness (penalty kicking), consistent handedness, gender differences, familial sinistralty (FS+), hand posture, and manual skills measured on three tests: Key tapping, Annett’s Pegboard, and circle-dotting. There were 286 individual twins (255 dextrals, 34 sinistrals), and 251 singletons (141 dextrals and 110 sinistrals). Data analyses revealed a three-fold increase on left-handedness among males than females. Furthermore, twin right- and left-handers were more mixed in their hand dominance and had a higher incidence of FS+ among first-degree relatives than singleton right- and left-handers. In line with previous studies, the frequency of contralateral kicking preference was higher in those with mixed than with consistent handedness, especially among left-handers. With regard to hand skill, no reliable between-group differences emerged on the three tests of manual skill. As per expectations, right-handers and left-handers were more proficient when manipulating the stimuli with their dominant hands. On all three measures, in contrast with right-handers, left-handers (twin and singleton) showed reduced between-hand asymmetries. By extension, the increased prevalence of left-handedness among twins could not be attributed to pathological influences, asymmetry reversal or birth order. It is possible, taking into the account the robust differences in mixed-handedness that the pattern of neuromotor lateralization might be more diffusely organized across the hemispheres in twins than in singletons, but this suggestion requires direct evidence, at least from neuroimaging experiments.
Acesso aberto (Open Access)
Pseudonegligência, dominância manual e habilidades motoras em alunos das artes em comparação com alunos de outros cursos
(Universidade Federal do Pará, 2008-05-02) MELO, Thiago Martins de; MARTIN, William Lee Berdel; http://lattes.cnpq.br/8591034699611752
A prominent line of research dealing with cerebral lateralization in artists have investigated the behavior of artists afflicted with various neuropathological syndromes affecting either the right or left hemisphere. In contrast, Bertrand (2001), noting that a few studies have reported an increased prevalence of left-handedness and ambidextrality among artists, suggested the need for systematic research into the laterality characteristics of normal artists. In the absence of such studies, and because it was not possible to obtain data from professional artists, this project was designed to investigate in detail, lateral asymmetries in handedness, motor abilities and visuospatial attention in art and non-art students. These students were recruited from the Art Department at the Federal University of Maranhão, and a public school of art in São Luis. There were 50 non-art students (24 right- and 26 left-handers), and 51 art students (27 right- and 24 left-handers) in the sample. Data were obtained on handedness, eyedness, and footedness, and two measures of motor proficiency: Finger tapping and the Grooved Pegboard Test. In addition, a version of the Visual Line Bissection Test (VLBT) was administered in order to compare the degree of pseudonegligence among and between art and non-art students. We sought to ascertain whether, in comparison with non-artists, the art students would evince a reduced degree of intermanual asymmetry in handedness and motor ability, as well as higher-level accuracy on the VLBT. Our predictions regarding such performance differences, were in fact, supported. Art students, especially left-handers were much less consistent, and more ambidextrous than dextral and sinistral non-art students, and displayed a lower between-hand performance on both motor tests. Also, whereas the degree of pseudonegligence was increased among non-art students, art students were more accurate in their responses, and produced fewer errors around the true zero point. Consistent with previous research among musicians, art students in general, showed a balanced level of visuospatial attention, and these differences were related to the cognitive demands of visual art training.