An examination of cortical thickness relationships within the reading network of adults

Much brain imaging work has underscored the functional connections among the inferior frontal gyrus (IFG; articulation), supramarginal gyrus (SMG; letter-sound correspondence), superior temporal gyrus (STG; sound) and fusiform gyrus (FFG; print) during basic reading processes. This reading network supports and coordinates the complex processes that contribute to successful reading. In line with the Hebbian notion that 'neurons that fire together, wire together' we examined cortical thickness among these regions and the extent to which these regions showed structural relationships in average and impaired readers. Structural high resolution brain scans from 87 adult participants including average (N = 56; 51 right-handed; females = 29; mean age = 20.5; SD = 2.14) and impaired (N = 31; 27 right-handed; females = 24; mean age = 23.1; SD = 4.23) readers were collated. Cortical thickness measurements of the left and right IFG, SMG, STG, and FFG were extracted. Average readers had significantly greater cortical thickness in the right IFG and right SMG compared to impaired readers. Within each group, similarly strong relationships between the left and right structures were observed. Average readers had a significantly stronger connection between the left IFG-FFG compared to impaired readers (p = 0.012). In contrast, the impaired readers had a significantly stronger connection between the left STG-FFG compared to average readers (p = 0.027). In conclusion, the findings suggest that structural relationships within the reading network may contribute to variations in reading proficiency, with average readers exhibiting distinct patterns of cortical thickness and relationships compared to impaired readers. Further exploration of these structural differences could offer valuable insights into the neural mechanisms underlying reading abilities and disabilities.