Kelly A. Vaughn (University of Houston), Aurora I. Ramos-Nuñez (University of Houston), Maya R. Greene (University of Houston), David Vasquez (University of California-Riverside), Adam Felton (University of California-Riverside), Christine Chiarello (University of California-Riverside), & Arturo E. Hernandez (University of Houston)
Cortical thickness; task switching; bilingual; inferior parietal lobule
Previous research involving patients with brain damage, children with ADHD, aging adults, Alzheimer’s patients, and normal monolingual children and adults suggests that cortical thickness in certain regions of the brain, specifically the dorsolateral prefrontal cortex, anterior cingulate cortex, inferior parietal lobule, and inferior frontal gyrus, is related to cognitive control abilities. In general, greater cortical thickness in these regions is associated with better cognitive control, and lesser cortical thickness is associated with poorer cognitive control. Surprisingly, researchers have not yet examined this relationship within the bilingual population, although bilinguals may have enhanced cognitive control abilities. Additionally, previous research suggests that greater grey matter density in one of these regions, the inferior parietal lobule, is greater for bilinguals than monolinguals, and is related to earlier age of second language acquisition, higher second language proficiency, more language exposure, and better overall language skills (Abutalebi, Canini, Della Rosa, Green, & Weekes, 2015; Della Rosa et al., 2013; Mechelli et al., 2004). Therefore, in order to fully understand the relationship between cortical thickness and cognitive control, it is important to examine the relationship between cortical thickness in the aforementioned regions and performance by bilinguals on a cognitive control task.
This study measured cognitive control using a non-verbal switching task in which participants switched between sorting images by color and sorting images by shape as indicated by a symbolic cue presented randomly throughout the task. Switch costs were calculated for the difference in response time and accuracy for the trial immediately following the switch cue or non-switch cue. Cue costs were calculated for the difference in response time and accuracy for the trial immediately following the cue and a later trial. Results indicate that, in this bilingual sample, cortical thickness is unrelated to reaction time costs for both switch and cue, but cortical thickness of the left inferior parietal lobule correlates with accuracy costs for both switch and cue. These findings shed light on the relationship between cognitive control and language in the brain.
 Abutalebi, J., Canini, M., Della Rosa, P. A., Green, D. W., & Weekes, B. S. The neuroprotective effects of bilingualism upon the inferior parietal lobule: A Structural Neuroimaging Study in Aging Chinese Bilinguals. Journal of Neurolinguistics, 33:3-13, 2015.
 Della Rosa, P. A., Videsott, G., Borsa, V. M., Canini, M., Weekes, B. S., Franceschini, R., & Abutalebi, J. A neural interactive location for multilingual talent. Cortex, 49(2):605-608, 2013.
 Mechelli, A., Crinion, J. T., Noppeney, U., O’Doherty, J., Ashburner, J., Frackowiak, R. S., & Price, C. J. Structural plasticity in the bilingual brain: Proficiency in a second language and age at acquisition affect grey-matter density. Nature, 431(7010), 2004.