"Resting-state functional connectivity correlates of linguistic development in infants and toddlers"

• In Event: Functional and structural findings from the Baby Connectome Project

Abstract

Language is a critically important facet of cognition, and notably, the cortical network supporting language processing is characterized by a dominance of the left hemisphere. This lateralization increases between childhood and early adulthood (Szaflarski et al., 2006), a time of dramatic increases in language skills. Functional magnetic resonance imaging (fMRI), due to its high spatial resolution and full brain coverage, is a tool well-suited to characterizing the distribution of cortical networks. However, the challenging scanning environment makes it difficult to image young children, meaning that there is a large gap in the imaging literature surrounding the ontogeny of the language network in this cohort, who are undergoing some of the most impressive changes in their linguistic skills.
Using the Baby Connectome Project (BCP; Howell et al., 2018) we studied the longitudinal development of the language network using a new resting-state fMRI (rsfMRI) technique (Day et al, in prep). We examined two regions of interest (ROIs) known to be involved in the adult language network: the inferior frontal gyrus (IFG; “Broca’s area”) and the middle temporal gyrus (MTG; “Wernicke’s area”) using ROIs created from the ABCD study (Hermosillo et al. 2022).
Our preliminary analysis subset of the complete BCP (n = 255-256; 510-511 timepoints) showed a low correlation between the two metrics (r = 0.29). Secondly, there emerged a non-linear relationship between age and laterality of the language network relative to the two ROIs. Both showed a general increase in laterality between approximately 12 months and 36 months, beyond which data becomes too sparse to draw conclusions about the trend.
However, between birth and 12 months, there is a U-shaped trend where laterality decreases from birth before increasing. This replicates a previous rsfMRI study of infants (Emerson et al., 2016) that found a similar effect, although we demonstrate in MTG an earlier peak of symmetry (8 months compared to 12).
Furthermore, we also demonstrate an attenuated trend in IFG relative to MTG, which mirrors the developmental trajectory of these two regions. In language acquisition, the MTG is involved in phonological analysis and word form detection (0 - 2 y), whereas the primary role of IFG in semantic and syntactic analysis is only beginning to emerge at 36 months.
These preliminary results demonstrate no correlation between laterality and language skill (as measured by the M.-B. Communicative Development Inventories) above and beyond that predicted by age. This may be related to using ROIs defined within ABCD that may not be suitable for infants and toddlers. Final analyses will include the entire BCP sample and use individualized ROIs for IFG and MTG rather than an out-of-group average.

Authors

• Trevor K.M. Day, University of Minnesota - Twin Cities
  Presenting Author

• Robert Hermosillo

• Greg Conan

• Anita Randolph

• Lucille A Moore, University of Minnesota - Twin Cities

• Audrey Houghton, University of Minnesota

• Damien A. Fair, University of Minnesota - Twin Cities

• Eric Feczko, University of Minnesota

• Jed T. Elison, University of Minnesota - Twin Cities