Socioeconomic status predicts hemispheric specialisation of the left inferior frontal gyrus in young children

Abstract

Reading is a complex skill that is not mastered by all children. At the age of 5, on the cusp of prereading development, many factors combine to influence a child's future reading success, including neural and behavioural factors such as phonological awareness and the auditory processing of phonetic input, and environmental factors, such as socioeconomic status (SES). We investigated the interactions between these factors in 5-year-old children by administering a battery of standardised cognitive and linguistic tests, measuring SES with a standardised scale, and using fMRI to record neural activity during a behavioral task, rhyming, that is predictive of reading skills. Correlation tests were performed, and then corrected for multiple comparisons using the false discovery rate (FDR) procedure. It emerged that only one relationship linking neural with behavioural or environmental factors survived as significant after FDR correction: a correlation between SES and the degree of hemispheric specialisation in the left inferior frontal gyrus (IFG), a region which includes Broca's area. This neural-environmental link remained significant even after controlling for the children's scores on the standardised language and cognition tests. In order to investigate possible environmental influences on the left IFG further, grey and white matter volumes were calculated. Marginally significant correlations with SES were found, indicating that environmental effects may manifest themselves in the brain anatomically as well as functionally. Collectively, these findings suggest that the weaker language skills of low-SES children are related to reduced underlying neural specialisation, and that these neural problems go beyond what is revealed by behavioural tests alone.

Stroop Color-Word Interference Test: Normative data for Spanish-speaking pediatric population

“…During the last couple of decades, several authors have directed their attention to the influence of family's socioeconomic level in the neurodevelopment of children, finding that language (Eckert, Lombardino, & Leonard, 2001;Noble, Wolmetz, Ochs, Farah, & McCandliss, 2006;Raizada, Richards, Meltzoff, & Kuhl, 2008) and executive functions (Hughes & Ensor, 2005;Mezzacappa, 2004;Noble, McCandliss, & Farah, 2007;Sbicigo, Abaid, Dell'Aglio, & Salles, 2013) are the most affected cognitive processes. Given that the parents' educational level is one of the variables that make up socioeconomic level (Hoff, 2006), it is expected that children whose parent(s) have a higher level of education will obtain better results in tests that measure executive functions such as the Stroop.…”

The neuroscience of poverty

“…Early-language expert Patricia Kuhl at the University of Washington used functional MRI to conclude that low-SES five-year-olds showed less specialization in a key region of the cortex implicated in reading (6). Helen Neville's group at the University of Oregon measured brain responses, called event-related potentials, to conclude that low-SES three-to eight-year-olds are slower to pay attention to a specified auditory input (7).…”

Effect of socioeconomic status disparity on child language and neural outcome: how early is early?

“…Among the youngest children analyzed for SES effects on brain structure are those reported by Raizada et al (89). In 14 children of diverse SES (58,59) who underwent functional MRI at age 5 y, SES predicted hemispheric specialization of the • n = 44 (44 F)…”