Comprehending text versus reading words in young readers with varying reading ability: distinct patterns of functional connectivity from common processing hubs

Abstract

Skilled reading depends on recognizing words efficiently in isolation (word-level processing; WL) and extracting meaning from text (discourse-level processing; DL); deficiencies in either result in poor reading. FMRI has revealed consistent overlapping networks in word and passage reading, as well as unique regions for DL processing; however, less is known about how WL and DL processes interact. Here we examined functional connectivity from seed regions derived from where BOLD signal overlapped during word and passage reading in 38 adolescents ranging in reading ability, hypothesizing that even though certain regions support word- and higher-level language, connectivity patterns from overlapping regions would be task modulated. Results indeed revealed that the left-lateralized semantic and working memory (WM) seed regions showed task-dependent functional connectivity patterns: during DL processes, semantic and WM nodes all correlated with the left angular gyrus, a region implicated in semantic memory/coherence building. In contrast, during WL, these nodes coordinated with a traditional WL area (left occipitotemporal region). In addition, these WL and DL findings were modulated by decoding and comprehension abilities, respectively, with poorer abilities correlating with decreased connectivity. Findings indicate that key regions may uniquely contribute to multiple levels of reading; we speculate that these connectivity patterns may be especially salient for reading outcomes and intervention response.

Figure 1

Sample stimuli from each of the three conditions.

Figure 2

A Boolean rendering of Passages > Symbols and Words > Symbols show that both Passagae reading and Word reading activate a dispersed, overlapping language and WM network. Results displayed at p-corrected <.05 (p-unc < .005, k=118).

Figure 3

Expository text comprehension, as compared to WL reading, uniquely recruits regions in the DMN, including bilateral AG, PCC, and bilateral anterior STS. Results displayed at p-corrected <.05 (p-unc <.005, k = 118).

Figure 4

(a) During Word reading only, word reading ability, as measured by Word Attack (green) and Letter Word Identification (red) measures, predicts activation in language regions, including the orthographic processing regions in the left OT area. Both measurements of word reading predicted activation in the left MTG (yellow). (b) Plot of LWID Percentile score by Words percet signal change in the left OT area. Low and high word reading ability (as determined by median split of LWID percentile) represented in dark blue and light blue, respectively. Results displayed at p-corrected <.05 (p.unc <.005, k=118).

Figure 5

(a) During Passage versus Baseline, RC ability predicts activation in both language and EF regions, including areas that support WM and the DMN. (b) Selected plots of Gates percentile by Passage percent signal change in L MTG, L IFG, and L AG (circled in yellow on (a)). Low and high RC ability (as determined by median split of Gates percentile) represented in dark blue and light blue, respectively. Results displayed at p-corrected <.05 (p-unc <.005, k=118).

Figure 6

Left-lateralized language regions of mean overlap activity in Passage and Word reading show differential connectivity patterns in WL (Words > Symbols; orange arrow) and DL (Passages > Words; red arrow) processes. Specifically, the three seeds show convergent correlation with the left OT area during WL reading, and additively shows correlation with the left AG during Passage reading. Results displayed at p-corrected <.05 (p-unc <.005, k=118).

Figure 7

Left pVWFA of mean overlap activity in Passage and Word reading shows differential connectivity patterns in WL (Words > Symbols; orange arrow) and DL (Passages > Words; red arrow) processes. During WL processes, pVWFA correlates with the left MTG and primary sensory regions. The pVWFA then additively shows correlation with the left AG, SMG, and language network/language homologues during Passage reading. Results displayed at p-corrected < .05 (p-unc <.005, k=118).

Figure 8

Left d1PFC of mean overlap activity in Passage and Word reading shows differential connectivity patterns in WL (Words > Baseline; orange arrow) and DL (Passages > Words; red arrow) processes. During WL processes, dlPFC correlates with the same left MTG area seen in the pVWFA seed connectivity analysis. The d1PFC then additively shows correlation with the left AG and left DMN during Passage reading. Results displayed at p-corrected <.05 (p-unc <.005, k=118).

Figure 9

Word reading ability positively predicts correlations between left pVWFA and left MTG in WL processing. Low and high word reading ability (as determined by median split of WA percentile) represented in dark blue and light blue, respectively). Results displayed at p-corrected <.05 (p-unc <.005, k=118).

Figure 10

RC ability positively predicts correlations between the left d1PFC and the left AG in DL processing. Low and high RC ability (as determined by median split of Gates percentile) represented in dark blue and light blue, respectively). Results displayed at p-corrected <.05 (p-unc <.005, k=118)