Avoidance-related lateralization
Research Papers
Modeling Development of Frontal Electroencephalogram (EEG) Asymmetry: Sex Differences and Links with Temperament
Asymmetric patterns of frontal brain electrical activity reflect approach and avoidance tendencies, with stability of relative right activation associated with withdrawal emotions/motivation and left hemisphere activation linked with approach and positive affect. However, considerable shifts in approach/avoidance-related lateralization have been reported for children not targeted because of extreme temperament. In this study, dynamic effects of frontal electroencephalogram (EEG) power within and across hemispheres were examined throughout early childhood. Specifically, EEG indicators at 5, 10, 24, 36, 48, and 72 months-of-age (n=410) were analyzed via a hybrid of difference score and panel design models, with baseline measures and subsequent time-to-time differences modeled as potentially influencing all subsequent amounts of time-to-time change (i.e., predictively saturated). Infant sex was considered as a moderator of dynamic developmental effects, with temperament attributes measured at 5 months examined as predictors of EEG hemisphere development. Overall, change in left and right frontal EEG power predicted declining subsequent change in the same hemisphere, with effects on the opposing neurobehavioral system enhancing later growth. Infant sex moderated the pattern of within and across-hemisphere effects, wherein for girls more prominent left hemisphere influences on the right hemisphere EEG changes were noted and right hemisphere effects were more salient for boys. Largely similar patterns of temperament prediction were observed for the left and the right EEG power changes, with limited sex differences in links between temperament and growth parameters. Results were interpreted in the context of comparable analyses using parietal power values, which provided evidence for unique frontal effects.
View Full Paper →Test-retest reliability of spectral parameters of the EEG
The topic of this paper is the intraindividual stability of the EEG at rest for repeated recordings with respect to two sets of spectral parameters. Variability arises due to changes in experimental conditions (such as vigilance) and also due to the inherent random elements of the EEG. The two sets of parameters considered are broad-band parameters and parameters characterizing rhythmic and ‘diffuse’ activity separately, derived from autoregressive fitting. In spite of some imprecision in the definition of the EEG at rest, satisfactory test-retest correlations were found. They proved to be quite homogeneous topographically, but not across frequency bands: delta power is less reliable and to some extent also beta activity, whereas the alpha bands perform well. The frequency of the alpha rhythm shows a good reliability and, given the difficulties involved with the concept, also the degree of synchronization. The power of rhythmic and of diffuse activity showed more modest retest correlations, probably to be attributed to methodological problems in determining these quantities. On the whole, the results confirm that the normal EEG can be treated as an intraindividually rather stable trait, that artifacts play a minor role in this respect and that 20 sec of activity are sufficient to reduce adequately the variability inherent in the EEG. Résumé Le sujet de cet article est la stabilité intra-individuelle de l'EEG de repos lors d'enregistrements répétés, ceci à partir de deux ensembles de paramètres spectraux. L'augmentation de la variabilité est due à des modifications des conditions expérimentales (telles la vigilance) ainsi qu'aux éléments aléatoires inhérents à l'EEG. Les deux ensembles types de paramétres considérés sont les paramètres de bande large et ceux individualisant une activité rythmique et diffuse à partir d'une évaluation autorégressive. En dépit de quelques imprécisions dans la définition de l'EEG de repos, des corrélations entre tests renouvelés satisfaisantes ont été trouvées. Elles se sont montrées tout à fait homogènes topographiquement, mais non entre bandes de fréquences: la puissance delta est moins fiable et dans une certaine mesure, l'activité bêta, alors que pour la bande alpha les résultats sont bons. La fréquence du rythme alpha présente une bonne fiabilité ainsi que son degré de synchronisation compte tenu des difficultés mêmes qu'offre cette notion. La puissance de l'activité rythmique et diffuse a apporté des corrélations plus modestes entre tests, probablement à cause de problèmes méthodologiques de détermination de ces quantités. En somme, ces résultats confirment le fait que l'EEG normal peut être traité comme une caractéristique intra-individuelle plutôt stable, que les artéfacts ne jouent à cet égard qu'un rôle mineur et que 20 sec d'activité sont suffisantes pour réduire de façon acceptable la variabilité inhérente à l'EEG.
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