Our first aim was to assess whether lateralization changed with age. For the language production task, we did not find any association between the direction or the strength of lateralization and age. This is in agreement with other fTCD studies Lohmann et al. One possible explanation for this result could be that developmental changes are area-specific Holland et al.
Another factor that likely contributes to the lack of association is that our language activation task likely involved language skills that mature early. Holland et al. For early acquired skills such as word-picture matching, age-related changes in lateralization were minimal. Our language production task required the description of simple animations which is achievable for four-year-olds Bishop et al.
As such the skills involved are probably early-acquired, and accordingly little age-related changes in lateralization were found. Differences between early- and late-acquired skills as proposed by Holland et al. In this context a recent study comparing functional lateralization for different language tasks is relevant Badcock et al.
They found that language lateralization derived from different tasks varies, but this variation could not be explained by task difficulty Badcock et al. As such it is unlikely that our lack of finding an association between language lateralization and age is due to differences in task difficulty. For the visuospatial memory task, the strength but not the direction of lateralization was predicted by age, with older children showing a more lateralized response.
This replicates work by, and corresponds with the hypothesis proposed by Holland et al. Children in the studied age range significantly improved their performance on the visuospatial memory task with age. Whereas younger children performed the task at level 3 or 4, progressively older children completed levels 5 or 6. The visuospatial memory task therefore appears to probe late-acquired skills that are still developing between six and 16 years of age. Nevertheless, it was striking that individual differences in task performance, as indicated by the level at which the experimental task was carried out, were not predictive of cerebral lateralization on this task.
Though, a similar lack of association between behavioral responses and functional lateralization has been reported in other studies assessing visuospatial attention Rosch et al. A limitation of our study with regard to assessing developmental changes in functional lateralization is its cross-sectional design. Repeatedly assessing functional lateralization in the same children at different ages would allow for stronger conclusions.
Our failure to find an association between lateralization for language production and gender is in accordance with other fTCD studies in adults Knecht et al. However, we did find a trend for gender to predict the direction of lateralization for visuospatial memory, indicating greater right-lateralized activation for visuospatial processing in boys compared to girls.
This is in agreement with findings for lateralization of spatial processing Voyer and Bryden ; Ernest ; Johnson et al. Given that the finding refers to a statistical trend, replication in a larger sample would be necessary to draw strong conclusions.
Our second aim was to consider how individual differences in patterns of lateralization relate to cognitive and language ability. The functional crowding hypothesis predicts poorer performance on cognitive and language tasks for children with both language production and visuo-spatial memory lateralized to the same hemisphere compared to children in whom these functions are lateralized to different hemispheres.
We did not find support for this hypothesis as no significant differences on cognitive and language tasks existed between the two groups. This is in contrast to the finding of a recent fTCD study in adults that people in whom functions lateralized to different hemispheres performed better on a dual-task than people with both functions lateralized to the same hemisphere Lust et al.
One possible explanation for this discrepancy is that cognitive performance as measured by means of dual-task interference is quite different from our cognitive and language ability measures. A second possibility is that the group in whom functions were lateralized to different hemispheres in the study by Lust et al. This latter group presents a crucial test case for the functional crowding hypothesis and children with this mirror image pattern were present in the current sample.
In contrast to the predictions of the functional crowding hypothesis, we found that children with language lateralized to the left hemisphere showed significantly higher scores on vocabulary and nonword reading, but not on nonverbal cognitive ability, compared to children in whom language was not lateralized to the left. This was the case irrespective of the status of lateralization for visuospatial memory. Together, these results suggest that lateralization of language function to the left hemisphere is advantageous to the individual and this advantage is independent of lateralization of visuospatial memory.
Our use of more specific tests of language ability and the inclusion of children from across the normal range of ability instead of well-educated university students are possible explanations for this discrepancy. The finding of a link between nonword reading and cerebral lateralization is consistent with a study by Illingworth and Bishop that used fTCD to demonstrate reduced cerebral lateralization for language in dyslexic adults.
Previously, where links have been found between language level and cerebral laterality, it has been noted that weak lateralization could be the consequence rather than the cause of language limitations. Reading development in typically developing five-year-olds was associated with a shift from bilateral to left-lateralized activation in the temporoparietal region with age whereas no such shift was observed in a group of children at-risk of reading difficulties Yamada et al.
This relation to absolute skill development does not bear out in our data as the associations found in the current study were with age-scaled scores; age, which is strongly associated with raw vocabulary level, was not a significant predictor of language lateralization and raw vocabulary and nonword reading scores did not differ between lateralization groups.
Although cause cannot be distinguished from consequence within the current dataset, the results suggest that skill level within an age band rather than absolute skill level was associated with lateralization for language production. As postulated by the Right Shift Theory, we found language advantages for those with left-hemisphere language.
Our findings differ from predictions of that theory in some details; in particular, the largest effect was seen for a vocabulary measure, whereas phonological skills have been emphasized by Annett and colleagues Annett and Turner ; Annett and Manning ; Annett ; Smythe and Annett Nevertheless, our findings suggest that individual differences in cerebral lateralization may influence language ability, and that such associations are worth investigating further with direct measures of brain function, rather than handedness, which is a weak and indirect indicator of language laterality.
Interestingly, our findings are also consistent with several brain imaging studies with typically developing children in the literature. For instance, reports on lateralization of the arcuate fasciculus, a major white matter tract connecting frontal and temporal language areas or their right-hemisphere homologues, show a similar association with language and literacy abilities Lebel and Beaulieu ; Yeatman et al.
Specifically, more leftward lateralization of the arcuate fasciculus was associated with better vocabulary and phonological awareness skills Lebel and Beaulieu and phonological memory and reading skills Yeatman et al. It remains to be seen whether structural differences between the hemispheres, including the larger cells, wider microcolumns, and larger spacing of macrocolumns in the left hemisphere Seldon ; Hayes and Lewis ; Galuske et al.
Combined structural and functional longitudinal neuroimaging studies would be necessary to assess this. In summary, no age-related change in direction or strength of lateralization was found for language production in our sample of school-age children.
In contrast, the strength of lateralization independent of direction for visuospatial memory function, continued to increase with age.
Having both language and visuospatial functions in the same hemisphere was not associated with poor cognitive performance and we therefore found no evidence for the functional crowding hypothesis. Holt for assistance with testing. National Center for Biotechnology Information , U. Journal List Brain Behav v. Brain Behav. Author information Article notes Copyright and License information Disclaimer. Margriet A. Published by Wiley Periodicals, Inc.
This article has been cited by other articles in PMC. Abstract In the majority of people, language production is lateralized to the left cerebral hemisphere and visuospatial skills to the right. Keywords: Cerebral lateralization, development, functional transcranial Doppler ultrasonography, language production, left hemisphere, right hemisphere, visuospatial memory.
Introduction Cerebral lateralization refers to the functional specialization of the two cerebral hemispheres. Vocabulary Receptive vocabulary was assessed using the British picture vocabulary scale, 2nd ed. Experimental paradigms In the Language Production animation description paradigm, participants watched clips from a children's cartoon Bishop et al.
Procedure Participants were tested in a quiet laboratory, a separate room in their school, a testing van, or at home. Results Mean activation plots for the two paradigms for the participant sample as a whole are shown in Figure 1. Open in a separate window. Figure 1. Effects of age and gender on cerebral lateralization Next we explored the extent to which lateralization for language production and visuospatial memory was influenced by age and gender.
Table 1 Results of the regression analyses. Figure 2. Table 2 Means standard deviations , independent t -tests, and effect sizes for performance on cognitive and language tests for children with language production and visuospatial memory lateralized to different hemispheres Different or the same hemisphere Same.
Different Same t p r N 35 20 Age Figure 3. Table 3 Means standard deviations , independent t -tests, and effect sizes for performance on cognitive and language tests for children with language production lateralized to the left hemisphere Language Left or not Language Other. Discussion In this study, we assessed cerebral lateralization for language production and visuospatial memory in a group of 60 typically developing children between the ages of six and 16 years.
References Annett M, Turner A. Laterality and the growth of intellectual abilities. Reading and a balanced polymorphism for laterality and ability. Child Psychol. Left, right, hand and brain: the right shift theory. London, UK: Erlbaum; Laterality and types of dyslexia.
Handedness and brain asymmetry. The right shift theory. Hove, UK: Psychology Press; Front Psychol. Using functional transcranial Doppler ultrasonography to assess language lateralisation: influence of task and difficulty level. Laterality: Asymmetries Body, Brain Cogn. Cerebral asymmetries in monozygotic twins: an fMRI study.
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The anatomo-functional connectivity of language revisited: new insights provided by electrostimulation and tractography. The British picture vocabulary scale. Spatial ability and lateralization in the haptic modality. Brain Cogn. Strengthening of laterality of verbal and visuospatial functions during childhood and adolescence.
Brain Mapp. Hemispheric lateralization of spatial attention in right-and left-hemispheric language dominance. Brain Res. Language and spatial attention can lateralize to the same hemisphere in healthy humans.
Gender-related differences in lateralization of hippocampal activation and cognitive strategy. Developmental aspects of language processing: fMRI of verbal fluency in children and adults. Functional anatomy of cognitive development: fMRI of verbal fluency in children and adults. Interhemispheric asymmetries of the modular structure in human temporal cortex. Where were those rabbits? A new paradigm to determine cerebral lateralisation of visuospatial memory function in children.
An fMRI Study of sex differences in regional activation to a verbal and a spatial task. Love words? Need even more definitions? Homophones, Homographs, and Homonyms The same, but different.
Merriam-Webster's Words of the Week - Nov. Ask the Editors 'Everyday' vs. What Is 'Semantic Bleaching'? How 'literally' can mean "figuratively". Literally How to use a word that literally drives some pe Is Singular 'They' a Better Choice?
The awkward case of 'his or her'. Take the quiz. In support of this view, another study found that patients who had suffered trauma to their left frontal lobe, particularly their prefrontal cortex experienced depression as a result Paradiso et al. Similarly, patients who had suffered damage to their right frontal lobes were found to be more likely to show signs of inappropriate cheerfulness and mania Starkstein et al.
This supports the idea that the left hemisphere is lateralized to positive emotions and the right is lateralized to negative emotions.
There are several studies which support the notion that there are differences in the lateralization of function in the brains of males and females. Tomasi and Volkow found that males had increased right lateralization of connectivity in areas of the temporal, frontal, and occipital cortices, whereas females had increased left lateralization of connectivity in the left of the frontal cortex. Reber and Tranel reviewed studies of brain differences in males and females and found a lot of evidence that there was sex-related difference in an area of the brain called the ventral-medial prefrontal cortex vmPFC , an area associated with decision-making and emotion.
Tranel et al. However, the only female patient with right vmPFC damage displayed fewer deficits in all behavioral categories. This evidence implies that lateralization of higher cognitive functions is dependant on the sex of the individual. The theory of brain localisation is supported by the famous case study of Phineas Gage who was an America railway construction foreman. During an accident a large iron rod was driven completely through his head, destroying much of his brain's left frontal lobe.
He survived the accident but his personality changed, he became unstable and is reported not to have been able to hold down a job. This supports the localisation of functions theory as it shows that control of social behavior is located in the frontal cortex. Olivia has been working as a support worker for adults with learning disabilities in Bristol for the last four years. Guy-Evans, O. Lateralization of brain function. Simply Psychology. Britannica, T.
Editors of Encyclopaedia , January Broca area. Encyclopedia Britannica. Editors of Encyclopaedia , March Wernicke area. Clements, A. Sex differences in cerebral laterality of language and visuospatial processing. Brain and Language, 98 2 , Gazzaniga, M.
Facial recognition and brain asymmetries: Clues to underlying mechanisms. Olulade, O. The neural basis of language development: Changes in lateralization over age. Proceedings of the National Academy of Sciences, 38 , Paradiso, S. Cerebral blood flow changes associated with attribution of emotional valence to pleasant, unpleasant, and neutral visual stimuli in a PET study of normal subjects.
American Journal of Psychiatry, 10 , Reber, J. Sex differences in the functional lateralization of emotion and decision making in the human brain. Journal of Neuroscience Research, 95 , Silberman, E. Hemispheric lateralization of functions related to emotion. Brain and Cognition, 5 3 , Sperry, R.
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