Patterns of structural lateralization in cortical language areas of older adolescents

ABSTRACT

Structural lateralization of cortical language areas has been extensively studied in the past, with the conclusion that there is a predominant left lateralization in the majority of typically developing adolescents. However, lateralization in this age group has often been examined using cortical volumetric measures, without taking into account the independence of surface area and thickness. Utilizing structural MRI data in a relatively large sample size, the lateralization of cortical volume, surface area, and thickness was analysed across regions of interest (ROIs) known to support language processing in 118 typically developing adolescents, ages 13;9 to 18;9 using a laterality index. Results showed that the laterality index scores for volume and surface area were more strongly correlated than volume and thickness. Results also showed that not all language regions were left lateralized, with some ROIs being significantly right lateralized. Results also showed that surface area and thickness did not always share direction of lateralization. Taken together these results indicate that cortical ROIs supporting language are not all strongly left lateralized in adolescents. These data also show that cortical surface area and cortical thickness need to be treated independently in future studies characterizing language and lateralization in the adolescent brain.

KEYWORDS:

• Hemispheric asymmetry
• language
• adolescent
• structural asymmetry

Acknowledgements

The authors gratefully thank the children, adolescents, adults, and parents who participated in the research. Data used in preparation of this study were obtained from the Pediatric Imaging, Neurocognition, and Genetics Study (PING) database. The PING investigators contributed to the design and implementation of the database but did not participate in the analysis or writing of this report. A complete listing of PING investigators can be found at http://ping.chd.ucsd.edu. Data collection and sharing for this project was funded by PING from the National Institutes of Health with grant RC2 DA 029475, which is funded by the National Institute on Drug Abuse and the Eunice Kennedy Shriver National Institute of Child Health and Human Development. PING data are disseminated by the PING Coordinating Center at the Center for Human Development, University of California, San Diego. A. M. D. is a founder of and holds equity interest in CorTechs Labs, La Jolla, CA, and serves on its scientific advisory board. The terms of this arrangement have been reviewed and approved by the University of California, San Diego in accordance with its conflict of interest policies. Data used in preparation of this study were obtained from the Pediatric Imaging, Neurocognition, and Genetics Study (PING) database. Parts of this research were reported at the Symposium on Research in Child Language Disorders in Madison, Wisconsin, June 2012 and the Society for Neurobiology of Language Conference in Chicago, IL, October 2015.

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCID

Meredith Scheppele http://orcid.org/0000-0001-6097-258X

Additional information

Funding

This research was supported by the National Institute on Deafness and Other Communication Disorders [grant number R01 DC5650], Julia Evans, Principal Investigator, by the Eunice Kennedy Shriver National Institute of Child Health and Human Development [grant number R24 HD075489], Timothy T. Brown, Principal Investigator, and by the National Institute on Drug Abuse [grant number R01 DA038958], Timothy T. Brown, Principal Investigator.